EF-UK Issue 83 - British Electric Flight Association

Transcription

ELECTRIC FLIGHT U.K.
ISSUE No. 83 WINTER 2005
THE MAGAZINE OF THE
BRITISH ELECTRIC
FLIGHT ASSOCIATION
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Electric Flight - U.K.
Issue 83 - Winter 2005
"To Encourage and Further all Aspects of Electric Model Flight in
the British Isles and Elsewhere" - B.E.F.A. Constitution
CONTENTS
BEFA Committee 2005/6 ........................... 4
Chairman's Chatter .................................. 5
Current Lines ........................................... 5
BEFA AGM 2006 ...................................... 6
Letter to the Editor .................................... 9
New-2-U .................................................. 25
TLC from your TLO ................................. 31
Readers’ Models ....................................... 37
The Electrifly PolyCharge4 ....................... 42
Fixing Günther Propellers ........................ 44
Wings & Wheels Model Spectacular .......... 47
NEAT Fair 2005 ...................................... 48
Perkins ARTF Tiger Moth ........................ 57
A Smarter Dart ....................................... 61
Intermodellbau 2005 ................................ 67
Event Calendar ....................................... 72
For Sale / Wanted .................................... 75
New to Electric Flight? Start Here ............ 77
BEFA Sales ............................................. 78
Advertisers Index ..................................... 78
Cover Photo: The cover photo is the Editor’s Scorpio threedee. It is powered by
a Typhoon 15 brushless motor, a Hacker Master 30-3P brushless controller and
3S1P Kokam 15C 2000mAh cells. It is fitted with a Ramoser Technik & Design
VarioPROP 2-blade hub with 9.7" Scale-Optic blades, set at approx. 5" pitch. This
setup gives a static power to weight ratio of almost 1.5:1 so vertical climbs are
effortless, even after a 10 minutes of aerobatics.
NEXT ISSUE. The copy date for the Spring 2006 issue is 28 February 2006, with
the magazine due for publication by 31 March 2006.
DISCLAIMER
B.E.F.A. and Electric Flight U.K. wish to point out that the content, techniques and opinions
expressed in this magazine are those of the individual authors and do not necessarily represent the
views of either the Editor of this magazine or B.E.F.A. and its committee.
© All information in this magazine is copyright of the authors. Any request to use information
from this magazine is to be made to the editor (contact details overleaf).
All reasonable care is taken in the preparation and compilation of the magazine, but B.E.F.A. and
its committee cannot be held liable for any error or omission in the content of this magazine or any
subsequent damage or loss arising howsoever caused.
To allow proper appreciation of the photographs used, colour copies of them will be posted on the
B.E.F.A. website after publication of this magazine. If you can, check them out at www.befa.org.uk
E.F.-U.K.
3
BEFA Committee 2005/6
Chairman
Robert Mahoney
123 Lane End Road, High Wycombe, Bucks. HP12 4HF
EMail: [email protected]
Secretary
Peter Turner
37 Church Street, Horsley, Derbyshire. DE21 5BQ
Tel: 01332 881 265, Email: [email protected]
Membership Secretary
Bob Smith
1 Lynwood Avenue, Tollesby, Middlesborough, Cleveland. TS5 7PD
Email: [email protected]
Treasurer
Bob Smith, details as Membership Secretary
EF-UK Editor
Jan Bassett
111 Plantagenet Chase, Yeovil, Somerset. BA20 2PR
Tel. 01935 472743, E-mail: [email protected]
Events Co-ordinator
Terry Stuckey
31 Dysart Avenue, Kingston-upon-Thames, Surrey. KT2 5QZ
Competition Secretary
Bob West
51 Haweswater, Huntingdon, Cambs., PE29 6TW
Tel. 07970 238 704, Email: [email protected]
Midlands Representative
Roger Winsor
14 Butler Gardens, Market Harborough, Leics. LE16 9LY
Northern Representative
Bob Smith, details as Membership Secretary
Southern Representative
Dave Chinery
251 Station Road, Hayes, Middx. UB3 4JD
South West Representative Jan Bassett, details as Editor EF-UK
Indoor & Free-Flight Rep.
Gordon Tarling
87 Cowley Mill Road, Uxbridge, Middx. UB8 2QD
Technical Liaison Officer
Alan Bedingham
17 Highcliffe Close, Wickford, Essex. SS11 8JZ
Public Relations Officer
John Thompson
19 Park Avenue, Liversedge, West Yorks, WF15 7EQ
Tel. 01924 515 595, Email: [email protected]
Webmaster
Jan Bassett, details as Editor EF-UK - (www.befa.org.uk)
Safety Adviser
David Beacor
34 Chestnut Close, Brampton, Huntingdon, Cambs., PE28 4TP.
Please enclose an SAE with all correspondence to the committee.
4
E.F.-U.K.
Chairman’s Chatter
Dear members,
Welcome to autumn 2005 issue of your association's quarterly magazine.
For once I can give you some good news! Lieutenant Colonel (Retired) R J Thayer
has graciously given his consent for us to hold our annual Middle Wallop event
with the normal conditions regarding the operations of our model aircraft.
So open your diary at the 1st & 2nd of July 2006 and reserve that weekend for the
BEFA Middle Wallop Electric weekend.
If you or your club is going to hold an electric flight event please let Jan Bassett
and myself have the information to put in this magazine and on the websites! I
can see the 2006 being very busy with electric flight events. It will pay to get your
dates in quickly to ensure you are first on any given day.
In would like to wish you all seasons greetings and a prosperous New Year
KEEP THE WATTS UP!
Robert Mahoney
Current Lines
from the Editor
Thanks again to all the contributors to this issue, you really make my life easier.
I do request that articles are sent electronically if at all possible as it saves me
retyping something that has normally been type once before.
Unusually I managed to hold a couple of articles over to the next issue, but that
still leaves most of the magazine to fill. My plea for articles and model information
is therefore just as urgent, please submit something.
This is my penultimate issue as Editor. We have a volunteer to take over the
magazine who is suitably experienced and keen. However, I may not
disappear completely from the pages of this publication as some fear
(or was it cheer!). I will offer my services to the new Editor in
commenting on articles if my services are a benefit.
I also plan to spend some of my freed time in building a number of
models that have been part started, sit in boxes on the top of
cupboards or are just in my mind. I will be submitting articles
on these projects, why don’t you do the same.
All the best for the festive period and 2006.
Regards
Jan
E.F.-U.K.
5
2006 Annual General Meeting
to be held at 2.00 pm on
6th March 2006
at the
Royal Spa Centre, Royal Leamington Spa, Warks.
with Traders’ Fair from 9:30am
Access will be allowed for the depositing of items for the Bring & Buy stand from
9.00 am. It is requested that anyone bringing items to sell on the Bring & Buy
stand complete the form (or a copy of it) overleaf before arriving. The is also
available from the event page of the BEFA website (www.befa.org.uk). It is
essential that all items are listed on the form and that all items are labelled with
a minimum of the sellers’ name and the price asked. The Bring & Buy stand will
stop trading at 1.00 pm to allow things to be cleared up before the AGM starts.
The main doors will open for access to the Bring & Buy and Traders’ Fair at 9.30
am. An admission fee of £3 will be charged for access to the Bring & Buy and
Traders’ Fair, being payable on the door.
Free access will be allowed to members after 1.30 pm so they can attend the
Annual General Meeting, which will commence at 2.00 pm in the Lecture Theatre
AGM Agenda
Minutes of the last AGM
Matters arising.
Annual Reports from the Chairman, Secretary & Membership Secretary.
Treasurers statements and review of the Statement of Funds
Agree the Annual Subscription for 2005/6
Appoint the Financial Auditor for 2005/6
Election of Committee Officers Secretary
Membership Secretary
Editor
Events Co-ordinator
Free Flight and Indoor Representative
Proposals: The Committee has proposed one resolutions (see facing page).
Nominations for the Committee positions due for re-election must be received in
writing by the Secretary (see page 4 for address) at least 15 days before the AGM.
6
E.F.-U.K.
The following change to the BEFA Constitution is proposed by the
Committee for acceptance at the 2006 A.G.M.
Clause 7 – Existing wording
7)
Election of the Committee.
The officers of the Committee will be elected at the Annual General Meeting
of the Association. Persons nominated for election must confirm in writing
that they are prepared to serve if elected and must be proposed and seconded
by paid up members. Nominations must be received by the Secretary at
least fifteen days before the date of the A.G.M. In the event of insufficient
nominations being received to fill all positions on the Committee, the elected
members of the Committee will have the power to co-opt any eligible member
who is prepared to serve.
The problem with this system is that it is very cumbersome and tends to discourage
nominations. This is particularly true in that we cannot accept nominations from
the floor at our AGM which is the one occasion when we might expect to find
volunteers. Under our present rules we can only co-opt such volunteers for a year
prior to their nomination at the following AGM which also puts their election out
of phase with our biannual pattern.
We would like to simplify this procedure such that we can also accept nominations
from the floor of the AGM to fill vacancies (supported by a proposer and seconder)
and that if successful, such nominees could begin to serve on the committee
immediately.
The Committee therefore proposes that clause 7) be modified as follows:7)
Election of the Committee.
The officers of the Committee will be elected at the Annual General Meeting
of the Association. The Secretary should normally receive nominations at
least fifteen days before the date of the A.G.M. Persons nominated for
election in this way must confirm in writing that they are prepared to serve
if elected and must be proposed and seconded by paid up members.
In the event of insufficient advance nominations being received to fill all
positions on the Committee, the committee may appeal for nominations for
these unfilled positions from the floor. Provided such nominees are proposed
and seconded by paid-up members, and are present at the meeting to accept
nomination, then they may also be elected by majority vote of the members
present.
Should this procedure still fail to fill the vacancies the elected members of
the Committee will have the power to co-opt any eligible member who is
prepared to serve.
E.F.-U.K.
7
8
E.F.-U.K.
Letters to the Editor
Firstly a letter from John Bunting ([email protected]) about Scale
Speed, following on from my comments to last issues TLC from your TLO article.
I'd like to discuss scale speed, and in particular Bob Boucher's article on the
Astroflight website, to which you refer in EF-UK 82. I'm perfectly happy to
be shot down if I'm wrong, but I'm not convinced by the idea that the model
speed should be derived by multiplying the full-size speed by the square root
of the scale.
Let's take a one-ninth scale Spitfire as an example. The full-size span is 36
feet, and typical speed 300 mph. The square root of one-ninth is one-third, so
the speed of the 4-foot span model, according to Bob, should be 100 mph. At
this point I begin to have doubts, which grow stronger when he talks about
'Scale Time', and says in the section headed 'Scale Size Loops' that the square
root factor applies here as well, so the model should do a loop in one third of
the time taken by the real aircraft.
Now, suppose you have a video of a real Spitfire doing aerobatics. You watch
it several times, and you have a good idea, possibly assisted by a clock display
in the corner of the screen, of how long it takes for the machine to do various
manoeuvres. For instance, you may notice that it typically takes about ten
seconds to do a loop.
Then someone shows you another video, also of a Spitfire. For the first few
seconds the machine is in steady flight, with a clear sky background, and you
might easily think it's a real aircraft. But then it starts doing aerobatics, and
the illusion is shattered, because it does a loop, not in ten seconds, but in
about three seconds, so you know immediately that it must be a model. So
much for realism.
To crown it all, Bob tells us, "These very high power military aircraft are very
difficult to model at scale speed". Well, I'm not surprised, if you think the
scale speed for a one-tenth scale P-51 should be 135 mph.
My conclusion is that this square-root-of-the-scale idea is misconceived. For
realism in flight, I think the speed should vary directly as the scale. In other
words, the real aircraft and the model should each take the same time to
cover a distance equal to their own length; in which case our one-ninth scale
Spitfire would fly at about 33 mph, and would do a loop in ten seconds. Not
always easy to achieve in practice perhaps, but that's another matter.
John raises a very interesting point in his letter and I’m sure it has merit. However,
I’d like to consider the issue in more detail. I’m not sure about the 300 mph speed
that John gives as typical. For completeness I’m going to compare the figures for
stall, manoeuvre and maximum speeds (in mph) for a Spitfire.
E.F.-U.K.
9
Spitfire IX
Boucher (1/3)
Bunting (1/9)
70
23.3
7.8
Manoeuvre Speed
215
71.7
23.9
Maximum Speed
408
136.0
45.3
Stall Speed
The Balsacraft Spitfire Mk IX is 1/9th scale and will be used to test the figures
above. A typically flying weight for the Balsacraft Spitfire with a Graupner Speed
600 Race 8.4v motor and 8 RC-2400 cells is 1.6 kg (3lb. 8oz.). This is a 14 oz.
below the Bob Boucher weight of 4 lb. 6 oz.
For this weight ElectriCalc estimates a stall speed of 17 mph. The Bob Boucher
figure is reasonably close and will be achieved. The figure using the scheme that
John proposes (7.8 mph) is not achievable unless the model weighs only about
300g (~11 oz.). Even if this low speed could be achieved, I don’t think that a
Spitfire would look credible at only twice walking pace. Certainly when it comes
to stall speed, I have to side with Bob Boucher.
It must be remembered that Bob Boucher says that the weight and power should
be reduced to one half of the calculated values for high power aircraft. This reduction
in power will inevitably mean that scale speeds will not be achieved. The 50% loss
of power will mean a speed reduction of around 25% at maximum power.
Another important factor at the upper speeds is that it is extremely rare for a
model to have a variable pitch propeller. This means we have to compromise on
propeller selection to get acceptable performance for take-off and climb out.
Applying the 25% reduction to the maximum speed from Bob Boucher’s system
gives a speed of 102 mph. This speed is still excessive and couldn’t be achieved
with the 266W (at the propeller) available at half scale power. Using this power,
it is probably realistic to expect 65 mph allowing for the scale lines.
I am fortunate to see the Royal Navy Historic Flight Hawker Sea Fury FB11 fly
regularly at RNAS Yeovilton. When you see this superb war bird hammer across
the sky at around 450 mph it is an amazing sight (and sound). It is surprising
how much sky an aircraft covers at these speeds, at a scale distance you could get
whiplash. Because of that I think that John’s maximum speed of 45 mph is just
too low, the model would appear very slow.
I have to agree with John about the times to complete aerobatic manoeuvres, but
it is a tricky problem. I think it important that the Manoeuvre Speed is considered
here as this is typically the limiting speed for such antics. The Manoeuvre Speed
using John’s recommendation is 23.9 mph, which would make it almost impossible
to complete a loop. Again Bob Boucher’s speed is unreasonably high and would not
be achievable.
The solution is probably to fly at an intermediate speed and to enlarge the diameter
of the loop slightly. You may not get to 10 seconds, but it will look better.
10
E.F.-U.K.
Next is a series of letters / emails from Peter Vivian following on from his article
“Some LiPo Experiments” in the last issue. I’m sure there are a lot of readers that
are unsure about LiPo cells and balancers, so it is worth printing the whole history.
I was interested to see that you published my LiPo experiments - as you say,
you are short of offers!
Seriously, one of the most important aspects of your efforts and contributions
to the BEFA is that you make comments upon articles you publish, comments
based upon knowledge and, more importantly, experience. This is important
because it encourages articles which might seem pretty basic to some but can
have serious input to even the "experts" when your comments are added. So
I am afraid your plan to retire is not welcome.
To get to my article, firstly I may have given a slightly incorrect impression
- I am not totally new to electrics, just electric flight. In fact I am (or was) an
electro-chemist and at one time I actually designed and made batteries! Seawater activated, ever heard of them? Think of the problems of series-connected
open cells in a common electrolyte, the sea! So Ohms Law etc are not exactly
egghead science to me.
But to your comments in that article. Firstly, no I did not actually charge at
1C. I gave the charger, a Mercury EX as I said, all the details it requested type of cell, capacity, charge rate (1C) etc and the charger decided what to
actually do when I switched it in. It started quite quickly to charge at 1C but
then the current dropped off pretty rapidly towards about half that figure
and carried on down. So recharging was in fact a long process. Now either
I could assume the charger knows best or override the charger or buy a new
charger. You imply the latter, I prefer the former because then I do not blow
batteries up but others do! But if you know of a safe charger which will give a
fairly level charge rate to a LiPo cell, much as my EX does to a NiMH or
NiCd, please tell me.
As for balancing leads, firstly my LiPo do not have them, I had to do that.
But then, connection to a connector is space & weight when you think of the
current-carrying capacity needed by wires and connector. And I am suspicious
of "balancing chargers". How many people actually bother to do what I did after some use and final charge disconnect all cells and check the after-charge
voltage of each individual cell. I think most people believe what they are told.
If they checked they may be a bit disenchanted - or wreck the battery!
Finally, you compare 5S2P Kokam with 18S GP3700. Surely more exactly
this should be 6S2P Kokam? (6 x 4.1 = 24.6, 18 x 1.35 = 24.3 OR 6 x 3.7 =
22.2, 18 x 1.2 = 21.6) But anyway, is there a charger which can charge at that
voltage? You also say that LiPo will charge in 90 minutes. Well, that was a
major point of my article, I found that they will not equally charge in that
time (or any other time) if connected up in series. The same amount of
E.F.-U.K.
11
current passes through each (Kirchoffs Law) but because the voltage drop is
different across each cell the wattage per cell is different. Yes, in parallel
probably but my results show that 5S (or 6S) charging is not acceptable after
a time, the cells go too far out of balance. And they do so for exactly the
reason you say, different internal resistances which are exacerbated by repeated
charging. So, LiPo or NiMH? High cost, low weight, long charge time (in
reality) versus lower cost, higher weight, shorter charge time. I have the
impression that you favour LiPo - or have I got that wrong?
Anyway, please keep up the good work. And incidentally, another of your
contributors to the same issue, Nick Fitton, rang me and we met up at a
suitable hostelry. We had a very interesting couple of hours during which he
strongly advocated Motocalc when trying to convert an IC to electric. I have
downloaded it but I am not too sure yet - but of course not sufficiently
experienced with it probably. Any comments?
Do I have any comments, it would be surprising if I didn’t
I thought your article was extremely useful as it allowed the explanation of a
number of issues.
I appreciate what you say about the worth of my comments, but I've spent
thousands of hours doing the magazine over the last 5 years and now I want to
do some more hands-on modelling. I've a number of projects I want to do but
can't find the time whilst editing the magazine and working full time. I am
not adverse to helping out the new editor and may still be making comments
once the new editor has taken up post.
I know a little about immersion batteries, salt and fresh water - they are used
in a number of military projects that I am, and have been, involved in. It is
always difficult to know at what level to pitch information, but there is always
someone out there without the basic knowledge.
From what you say it seems that the Mercury charger is extremely cautious
in charging LiPo cells. My Schulze chamelëon isl6-330d & isl6-430d chargers
will both complete a 1C charge in around 90 minutes, whilst still following the
charge guidelines.
My isl6-430d charger also
has a RS-232 output,
which allows connection
to a PC to monitor or plot
the (dis)charge. I've
attached the graph from
a charge conducted today
on my Kokam 2000mAh
15C 3S pack, which is
starting to loose capacity.
12
E.F.-U.K.
Both these Schulze chargers can charge up to 11 LiPo cells and at currents up
to 5A where the pack allows. I am rapidly starting to think that a balancer or
balancing charger is advisable for every charge. These limit the voltage across
each cell to a maximum of 4.2V. The excess power is dumped by the balancer
circuit so that the cell itself isn't passing the full charging current. Thereby
each cell can charge to full capacity unaffected by the other cells. With external
balancers connected I would have no qualms about charging an 11S pack with
the Schulze chargers.
I am looking around at different balancers and balancing chargers and may
well put an article in the next issue on them. To use a balancing charger no
disconnection of cells is required provide the pack was wired for balancing in
the 1st place. All recent packs seem to have balancing leads, which means the
cells must be paralleled and then connected in series. Unfortunately there is
no standard balancing connector, which means that adapter lead need to be
used for most packs.
You are quite correct, I must have hit a 5 instead of a 6 and the spell checker
wont spot that.
I tend to prefer ElectriCalc to MotoCalc as the results are immediate. By
changing the equipment or settings you can see the effects immediately. I do
also use MotoCalc, but it takes a little more getting used to and I find it more
time consuming.
Peter Vivian the responded with a follow-up message:
Thank you, that charging graph is interesting and I shall draw up a
comparison with my Mercury charger. Long hand of course, no PC connection!
And most interesting is your input on chargers generally, I shall have to look
into it and see what I can afford.
I would look forward to an article on balancing please - I still have doubts
and I am sure that some people are being fooled. You say all recent packs
have balancing leads. Really? From what little have seen I fail to understand
the logic, some people seem to think that because you can see cell
interconnection leads and the battery has a connector on the end of 2 wires
this is a balancing system. You will know this is rubbish, but much more
basic technical data is needed - right down to basics.
Personally I fail to see, at the moment, how any series connection can be
balanced without breaking/making connections. Kirchoff's Law, "the current
through components in series is equal in all parts of the circuit" means that
irrespective of the state of charge all series cells will have the same current
passing through them. Parallel cells will of course have different currents
passing through depending upon their internal resistance - and state of charge
- and so will eventually balance.
E.F.-U.K.
13
So a "basics" article would be most welcome, to very many people I think and
not just to me - but perhaps less so to battery dealers!
Best regards and many thanks. You will be missed but when work gets in the
way of other interests it is always a problem - one I no longer have!
Before I had chance to respond, Peter sent anther email:
I attach a graphic representation which is designed to show my concerns
about charger "balancing" and your comments would be appreciated.
Assume that I have 6 LiPo cells each of 2500 mAh, part discharged.
Now, I have named these cells cell 1, cell 2 etc and connected them up in
parallel pairs to make 3 off 1S2P batteries, labelled Battery 1, 2 and 3. The
"ohmic impedance" of each cell has been measured, commonly referred to as
internal resistance but that is not really the correct term.
Internal resistance is more exactly a fixed manufacturing condition whereas
the total impedance depends not only on that but the stage of charge, the
temperature, electrolyte and electrode conditions, contact resistance etc. etc.
However, the effect is much the same at the start of charging.
Then I show these batteries connected up in series and you will see from the
diagram that if charging commences at 5 amps (1C) then 13 volts is the
applied voltage. Using maths you can see the effective resistance of each 2cell battery and hence the voltage applied over that battery, the current passing
through the total 3S2P battery and the current passing through each cell.
Same current through each battery, different through each cell of course.
14
E.F.-U.K.
Now, the parallel pairs will eventually balance. Take Cell 1 and Cell 2, after
a time the different current passing through will charge the lower one to
catch up with the higher - they essentially have to reach the same voltage
because the higher-voltage cell is "charging" the lower one until voltages are
equal. Until that happens the cell at the higher voltage will be constantly
trying to input into the lower, so voltage balance is unavoidable.
However, since equalisation of impedance would depend simply on luck there
is little chance of the cells having equal capacities. Provide they are used in
parallel that is of little problem because, as with charging, they will "correct"
each other as they discharge. Well, they should but I have so far failed to
confirm that.
However, if we look at the other pairs of cells, the other batteries numbers 2
and 3, they can never achieve the same voltage. Each of the series-connected
2-cell batteries will receive the same amount of current for the whole of the
time they are on charge (unlike those connected in parallel) and because of
the different impedances, to say nothing of capacities, they will have different
final voltages. If charging ends when, say, the total voltage of the 3S2P
battery is 12.3 volts then each 2-cell battery may differ substantially - could
easily be (as I know) 1 at 3.9 volts, 1 at 4.1 volts and 1 at 4.3 volts, a difference
of 9% between highest and lowest. Not the way for a long life. The only way
they can match is for each 2-cell battery to be charged up separately to the
same final voltage. But it is claimed that a "balancing" charger can compensate
in some way, can "bleed off" the overcharge being offered to the better battery
and concentrate on boosting the lesser charged ones.
OK if that is true why can no-one explain to me what the connections are,
how it works. I have been told that it works by "rewiring" the cells and
connecting them all up in both parallel and series/parallel. Oh yeah? It
would be possible to have a connector panel (high current capacity PC board?
Difficult) such that cells are connected to one set of terminals in series/parallel
and another set in parallel only. Then applying charger leads to the parallel
set only would charge all cells up to equal voltage. Then connecting to the
series/parallel set for discharge would give you the required output voltage.
True, but in this simple little case 6 cells of 2500 mAh would need to charge
at 15 amps for 1C charging. Now imagine a 6S2P battery, 12 cells each of say
2500 mAh. All magically connected in parallel, charge at 30amps and hope to
finish in 90 minutes. 400+ watts and a sick car battery! Or 5 amps for 9
hours. Or 10 minutes flying time and go home. Or take out a second mortgage
for a bag of power packs.
Or am I badly wrong somewhere?
I have not put in all this information in the belief that I am teaching you
anything or telling you anything you do not already know, but simply to
show exactly where I am coming from so that you can teach me - and others!
E.F.-U.K.
15
Not wanting to write an article on this (I have far too much to do and too little time
already), I decided to respond to Peter directly and include the text in the ‘Letters
to the Editor’ feature.
I appreciate your concerns, but they are unfounded when using a balancing
charger or external balancer. There is no need to perform any soldering or
change pack connections to achieve balanced charging. Hopefully the following
will explain it properly.
Firstly, the limiting voltage for a 3S pack should be 12.6V (4.2V/cell) and
therefore 13V should never be seen. If a LiPo charger is at 13V when set for 3S
there is a serious safety fault with it and it should not be used.
I have modified your spreadsheet to show the action of the balancer circuits.
Charging at 5A with balancers connected
Each balancer is a variable resistance provided by a FET, which dissipates the
unwanted current as heat. Typically they start to operate at 4.21V and limit
individual cell groups to 4.25V. This is so that they don't interfere with the
function of the charger. As the pack nears fully charged, the pack voltage
rises to 12.6V and the charger will limit it to that.
If one group on a 3S pack is extremely low it could be at 4.1V, with the others
at 4.25V. As the voltage on this group increases above 4.1V, the voltages
across the other packs will drop, maintaining the 12.6V overall.
You will notice on your diagram that cells 4 and 5 are exceeding the 1C charge
current of 2.5A. I produced another chart at 4.5A (0.9C), but cell 5 still exceeds
the 1C cell rate at a pack rate of 0.8C. Reducing the current further to 4A
(0.8C) drops the current to an acceptable level. For this last diagram I had to
16
E.F.-U.K.
Charging at 4.5A with balancers connected
increase the resistance of each cell otherwise the voltages were all below 4.2V
and the balancer would have been doing nothing.
This is one of the reasons why we recommend a maximum rate of 0.75C when
charging packs connected in parallel. This reduces current means that the
cells should stay in the safe zone even when considerable imbalance is present.
In most case the negative of cells 1 & 2 and positive terminals of cells 3 & 4
share a single pin on the balancing connector. Thus a 4-pin balancing connector
is all that is required for a 3S pack. Most LiPo balancers have an LED that
Charging at 4A with balancers connected
E.F.-U.K.
17
shows when 4.2V is reached on each paralleled group (e.g. R1 + R2).
The critical point is that each of the paralleled groups must be connected to a
balancer otherwise the voltage on those cells is completely uncontrolled and
could rise to dangerous levels.
Hopefully this and the spreadsheet all make sense, if not please ask for
clarification.
Peter responded with a long letter:
Thank you for your e-mail of the 10th Nov. Now all is clear, I had never
considered the use of a FET for “switching off” the charger, in fact I just did
not realise how cheap they are today and such a means would never have
crossed my mind. That said, I still have a problem. This may be because I
am “out of date” with FETs or may be because you are simplifying things for
general consumption.
Firstly, a FET has 3 terminations in my world, Source, Drain and Gate, but
in your diagram you show only two so I am not clear on your connections.
Next, so far as I know, and I am an Electro-Chemist not a Physicist or
Electronics man, a FET works by conducting a signal down a “channel” from
Source to Drain unless a positive charge is applied to the Gate. Such a
charge, as it increases, reduces the Drain effect (reduces the current flow) by
increasing the resistance of the channel. This resistance increase carries on
as the Gate charge voltage rises until the channel is totally “blocked”, no
more current can pass.
The voltage at which this total blockage occurs depends upon the design of
the FET, for use on LiPo balancing a FET would be selected which “switches”
at 4.2 volts. And it should be noted that at this point current flow ceases, it
is not dissipated as heat. Such an action is not possible, current flows from a
higher Potential Difference to a lower but it cannot be dissipated (Kirchoff’s
Law). The effect of that, again so far as I understand, is illustrated in my
attached Method 1 schematic and explanation. When a cell is fully charged
then the charged Gate stops an current flow, throughout a total circuit of
series connections.
However, you appear to show the FETs connected in parallel with the cells
and if this is correct it demonstrates a technology and FET property of which
I have no knowledge - it would need in effect FET to be normal resistive in the
Source to Drain channel, not conductive, until a charge is applied to the
Gate. By this means, as the cell charges up so the Gate charge would increase
and the channel would open, and at 4.2v (for a LiPo) the channel would be
totally conductive.
All the current would cease to flow through the cell, it would bypass the cell
and go down the channel to the next cell. This would have the advantage of
maintaining current flow through the 3S system even when one cell was
18
E.F.-U.K.
Method 1
Three FET devices are connected in series with 3 LiPo cells as shown below.
Note the 3 FET leads, SOURCE, DRAIN and GATE. The Charger is connected
negative to Lead 1, positive to Lead 4 and set up to charge 3 LiPo cells at 1C.
The Red part of the FET is totally resistive at all times so does not conduct
but the Black “conductor channel” conducts, so current (the same current)
passes right through the FETs and charges up the cells. However, as a cell
charges up its +ve voltage becomes greater of course and something called a
“field effect” puts a +ve charge on the Gate.
Now this increase in the “positiveness” of the Gate effectively “squeezes up” the
“conductor channel” and when the +ve reaches its “switching” limit (4.2 volts
for LiPo cells) the conductor channel actually becomes effectively “blocked”
and hence a total resistor and so it stops any more current flowing-hence
there is no more charging of anything.
So when the first cell to reach full charge “blocks” the conductor it blocks all
current flow so all charging ceases. No cell can become over-charged, but of
course two cells will remain under-charged. Probably not by much, but not
acceptable. The charger should indicate which cell is fully charged, and let us
say it is Cell 2. So now we have to “top up” Cells 1 &3.
So we firstly put the charger negative to Lead 1 and positive to Lead 2 and set
the charger to charge 1 LiPo cell at 1C. Again, when the +ve of Cell 1 reaches
4.2v the field effect from the positive of Cell 1 puts 4.2v on Gate 1 and FET 1
stops conducting. So Cell 1 is now fully charged but Cell 3 still needs a bit
more so we repeat as before, put the charger –ve to Lead 3 and positive to
Lead 4 and set the charger for 1 cell 1C. These “topping up” operations should
only take a few minutes but if it takes much longer it means that cell was very
out of balance and it is just as well you discovered it!
charged, and it would continue for the remaining 2 cells and then finally the
remaining 1 cell. There would be no need to “top-up” any cells separately as
would be needed with my Method 1. I show all this graphically in my Method
2 schematic, but I must emphasise that although I am conversant with FETs
of Method 1 I have no actual knowledge of Method 2 and all that I have
written is pure speculation. Be good if it was correct!
E.F.-U.K.
19
Method 2
Three FET devices are connected in parallel with 3 LiPo cells as below. Note
the 3 FET leads, SOURCE, DRAIN and GATE.
The Charger positive is connected to Lead 1, negative to Lead 2 and set up to
charge 3 LiPo cells at 1C.
The Red part of the FET is totally resistive at all times and at the start so is
the Black “conductor channel” which can conduct under certain conditions see later - but which is a total resistor at the start.
So current (the same current) passes right through the cells and charges them
up. However, as a cell charges up its -ve voltage becomes greater of course and
something called a “field effect” puts a -ve charge on the Gate.
Now this Increases the “negativeness” of the Gate which effectively “opens up”
the “conductor channel” and when the –ve reaches its “switching” limit (4.2volts
for LiPo cells) the conductor channel actually becomes effectively “open” and
hence a total conductor of no resistance. So the current by-passes the fully
charged cell and so the cell does not overcharge.
Because there is now less resistance in circuit the charge current drops but
the remaining two cells continue to charge up.
The next highest charged cell will then “shutdown” as it fully charges, followed
by the third one.
However, what this means is that for Method 1 the cell manufacturers would
need to supply flying leads. For a 2S there would be 1 positive and 2 negatives
(one to each cell) or for a 3S 1 plus 3 and so on. I can find no evidence of
Kokam or any manufacturer doing this except PolyCell - ignoring simple 2S
systems with centre pole connection. But I am sure you know better so please
let me know, I am sick of soldering and unsoldering LiPo cells, I have wrecked
2 so far and I am supposed to know what I am doing! As to packs with
balancing FETs fitted, sounds good but for me only if connections are visible
and can be reached with meter or clip contacts. I would prefer to be able to
20
E.F.-U.K.
buy a PC board with assembled FETs, say for a 2S or a 3S or a 4S (or
whatever the limiting series charging is today) and plug/unplug this to/
from the factory-installed battery flying leads. Or, how do I specify and
where do I buy such FETs, to make my own balancer?
Finally, how can any model shop claim to sell a “balancing charger” to plug
into a battery? I cannot visualise any such thing. In spite of you saying there
is no need for a soldering iron I remain certain that connection to each cell is
essential and if not factory supplied we must do it ourselves. Yes, if my Method
2 works you would be able just to connect up a FET-fitted battery to a suitable
charger - but such a charger would simply have a limiting capability not any
balancing capability and should not be so described.
But again, if I’ve got it wrong I would be delighted to be told.
OK, a lot to cover, so here goes.
In my last response I did simplify things in an attempt to make it easier to
understand the principle. I also erred slightly, what I should have said is that
each balancer circuit contains a FET. Peter is correct that FETs have 3 leads
as identified. However, FETs are available in a number of different varieties
with very different characteristics. The majority of FETs available do not
conduct when the Gate voltage = Drain voltage, which means they are “off”
when power is initially applied.
Over the past few years the “on” resistance has reduced markedly, with surface
mount FETs available as low as 6mÙ for a single FET. This ultra low resistance
means very low loses and that these small packages can handle higher currents
than their predecessors. This is one of the main reasons for the reduction in
cost and size of speed controllers as less FETs are required. For brushless
controllers this is a major advantage when 6 banks of FETs are required.
Peter’s Method 1 could be used, but if that was to chosen method it would be
better incorporated in the charger. Provided the voltage across each cell can
be maintained it would work. I consider that this method is unnecessarily
complicated and would not be cost effective.
Method 2 is along the lines used by commercial balancers, although you can
do it as simply as this. I’ll describe how a typical LiPo balancer circuit works
in the following paragraphs and hopefully everything will become clear.
A LiPo balancer typically contains a precision voltage reference, a voltage
comparator, a number of discharge resistors, a pulse-width modulator (PWM),
and a FET. The voltage reference is used by the comparator to produce an
error signal. This error signal controls the PWM, which turns the FET on
and off. As the voltage rises above 4.21v, the PWM starts with short pulses,
which increase in width until, the FET is always on at 4.25v.
Typically they also have a LED on the board, which indicates what the balancer
E.F.-U.K.
21
is doing. If the LED is off the battery voltage is below 4.21v. The LED lights
once the PWM circuit starts to operate and effectively indicates the pulse length
being produce (although at a much slower, visible, rate). If an LED is constantly
lit, the balancer is at maximum load and the voltage could be above 4.25v. To
ensure that no damage is done the charging current needs to be immediately
reduced to a level that all the LEDs are flashing or off. As the charging cycles
nears completion the LEDs will extinguish as all the cells are below 4.21v.
Some balancers are designed to be permanently connect across the cells, whilst
others are connected only when charging. Those permanently connected have
some advantages as they can’t be forgotten, however, you will need a balancer
for every series cell in your packs. To explain, a 3S1P pack would require 3
balancers, a 3S2P pack requires 3 balancers and a 5S4P packs requires 5
balancers. As you can imagine this will be expensive if you have a lot of packs.
Balancers that plugged in to external connections offer a method of balancing
all your cells, whilst keeping the costs down. I said it before, but I’ll repeat it
again here - it is essential that every series cell in a pack on charge is
connected to a balancer.
Balancers have a limit to the current that they can sink. Cells can be charged
at currents considerably above the balancer rating provided they are sufficiently
well matched. In the example I gave in one of the earlier responses, the balancer
was required to sink 514mA to limit the voltage at a 5A charge current. If the
balancer could only sink 250mA it would not be able to control the voltage,
which would rise to approx. 4.50v - extremely unsafe.
Please bear in mind that the above is typical, but wont be the case for all
balancer designs. Please read, understand and follow the instructions supplied
with the balancer you are using.
I’ve hunted around to find balancing chargers and balancers to provide the
best list I can of those currently available. The list is not exhaustive and I’d be
interested in details of any others that are known.
Balancing Chargers
Make + Model
Schulze LiPoCard
Cells LiIo LiPo Max I Comments
1-4
Y
Y
3.85A PC Interface, Auto setup
The Schulze LiPoCard in use on a 3S1P Kokam 2000 pack
22
E.F.-U.K.
Cell Balancers
Make + Model
Cells LiIo LiPo Max I Comments
Astroflight Blinky
1-6
N
Y
200mA
CSM LiPo Balancer
1
N
Y
335mA Designed for permanent fit
DualSky Balancer
3
N
Y unknown
FlightPower Duralite
3
N
Y unknown
FlightPower Duralite
2-6
N
Y unknown
Graupner Micro Bal
1-5
N
Y
Hyperion EOS LBA6 2-5
N
Y 6A charge Charge & discharge control
100mA
MGM Compro BLCR-4
2-4
N
Y unknown
Orbit LiPo-Checker
1
N
Y
550mA Supplied as a block of 5 units
Pro LiPo Balancer
1-6
N
Y
350mA
Schulze LiPoBal08
1-8
Y
Y
Schulze LiPoBal14
1-14 Y
Y
Sky-Holic H021
2.4
N
Y
300mA
Thunder Power
2-5
N
Y
420mA Linkable to some TP chargers
The only unit I have experience of is the Orbit LiPo Checker, which is available
with (•58.60) or without (•44.60) BEC type leads from http://orbitronic.de. These
units are used by Jean-Paul Schlosser (JéPé) and I found these units very good
and wont charge 2S+ packs without them connected.
Astro Blinky
Sky-Holic H021 Balancer
5 Orbit LiPo Checkers
Schulze LiPoBal 14
E.F.-U.K.
23
If your packs do not have balancing leads fitted it is relatively simple to fit them to
your packs. To fit a lead all that is needed is a suitable connector, some heatshrink
tubing, a soldering iron and a little solder.
The connector can be of any type to suit the balancer you intend to use but 0.1”
pitch Molex connectors are a good choice. If using the Orbit LiPo Checker with
the supplied BEC leads, use these connectors for the balancing leads.
Firstly carefully remove the heatshrink sleeve from the pack and expose the soldered
connections to the cells. You may find that hot glue has been used to stop the thin
electrodes from moving about, this will need to be removed from the soldering
area.
It is easiest to solder to the
electrodes where they are
already covered in solder from
the original connections.
Carefully solder the leads to
the terminals, as shown in the
photograph and diagrams
below, minimising the heat
applied to the electrodes.
Reapply hot glue or epoxy to
protect the electrodes from
flexing and re-cover the pack
with heatshrink.
24
A 3S pack of 15C Kokam 2000 mAh cells with
balancer lead retrofitted.
E.F.-U.K.
New-2-U
A Brief Round-up of New Items of Interest.
If you are a manufacturer or retailer that has something new they want to
share with the readers, please send details to the Editor (addresses on page 4).
Whilst this first item has been released for a while, it has not been seen in other
press or at any of the fly-ins I’ve attended. The Rödelmodell Kobra “Revival” is a
90cm (35½”) span, 79cm (31”) long sleek, moulded, twin boom, ARTF sports model.
The original Kobra was a
1980s model designed for
2cc glow motors, but this
latest version is solely for
electric power.
The flying weight is
intended to be around
950g (33½ oz.). Power is
an AXi 2820/10 on a 3S
pack of 15C 2000mAh
LiPo cells or similar,
giving unlimited vertical
performance and 10 to 12
minute flights.
The low weight and reasonable wing area also
give excellent slow speed handling.
As can be seen left, the wing and fuselage are
supplied as a single piece with tail boom
mounts, giving excellent strength for high
speed manoeuvring. The transparent or carbon
fibre canopy gives good access to the battery.
The Kobra is supplied with hardware and
decals (I’m not sure about the P-38 markings).
A power set containing the AXi motor, speed controller, battery pack, folding
propeller and hardware is also available.
It is available from the Rödelmodell online
shop at www.roedelmodell.de or contact
them on +49 82 68 713, by email at
[email protected] or by mail to
Rödelmodell GbR, Bernd & Petra Dörfler,
Lausangerweg 4, 86874 Mattsies,
Germany
E.F.-U.K.
25
Hyperion have recently released a new
range of outrunner motors, the Z-40
series. They have a 45mm diameter
stator, and is available in 3 different
lengths 25mm, 35mm and 45mm.
The magnets are specially made for
these motors and are curved on both
bell and stator sides. This maximises
heat transfer and improves the
magnetic flux.
They also feature shielded stainless
bearings. The motors also feature a large
ring bearing at the at the front of the
motor to prevent deformation of the bell
at high rpm. The motors can be back
mounted directly to a bulkhead or via the
mounting kit. They can also be mounted
using the rigid front mount, which can
be adjusted over a wide range of lengths.
Max Eff. I
(A)
Max. I
(A)
IO
(A)
KV
(rpm/v)
Ri
(mÙ)
Weight
(g)
Power
(W)
Z4025-10
40-60
80
2.96
560
16.2
356
600-1100
Z4025-12
35-50
65
2.38
486
21.8
356
600-1100
Z4025-16
30-40
50
1.85
368
37.2
356
600-1100
Z4035-10
40-60
78
2.38
405
18.7
446
800-1400
Z4035-12
36-53
65
1.98
343
26.1
446
800-1400
Z4035-14
33-44
57
1.80
299
34.5
446
800-1400
Z4045-10
40-60
77
2.05
320
22.1
553
900-1800
Z4045-12
35-50
63
1.63
275
31.3
553
900-1800
Z4045-14
31-40
48
1.50
236
40.9
553
900-1800
Model
A typical application is a 1/4 scale Ryan STA, 82” span, Hyperion Z4045-10 with
Hyperion Titan-90HV and 8S Hyperion 3700mAh 20C LiPo and APC 16” x 8” thin
electric propeller. This gives a flying weight of 12 lb. 4 oz. and draws 56A static
current at 27.9v, giving 1560W and 5790 rpm. After flight the calculated average
current was under 35A, motor was 51°C, the battery 36°C and controller 38°C.
The Hyperion Z-40 motors and back mounts are available online from Robotbirds
at http://robotbirds.com or contact them on 0208 841 7873.
26
E.F.-U.K.
Another recently introduced item by
Robotbirds is the nifty PJS 550R Double
Contra rotating brushless outrunner.
Stock is limited and they may have gone
by the time this is published, however,
contact them as they may get more.
The PJS 550R is designed for scale
models that need contra-rotating props,
in other words one propeller rotating left
& the other to the right. It has a
diameter of 32mm and an overall length
of 117mm and the weight is 139g.
The motors have a Kv value of 1300 rpm/v and are 100mÙ each. The suggested
propeller is 8” x 6” and you need one normal propeller and one with reverse pitch
(commonly called Left hand). The battery is 2 to 3 cell Lithium and the maximum
current is given as 21.7A per motor.
The price is a very good £69.95 +P&P. Contact details for Robotbirds on page 26.
Robotbirds have also just
introduced the Smart Charger
2020 (left), a 1 - 3 cell Lithium
Polymer charger with output
currents of 110mA, 250mA,
500mA, 750mA and 1200mA. It
is reverse polarity & short circuit
protected and measures only
90mm x 48mm x 11mm.
The input voltage range is 10.5v to 15v. It features power on LED, error LED,
charge complete LED and an LED for each cell connected. The settings are all
manual using jumpers on the right hand side. Price only £17.95 +P&P.
The final items included from
Robotbirds are 3 new carbon
undercarriage legs. They don’t state
the weight of the legs, but the following
information is available (all
dimensions in mm)
W
H
L
Model
Price
190
100
25
700g
£8
245
120
28
1000g
£9
290
145
35
1300g
£ 13
E.F.-U.K.
27
Here we have a new EDF jet model from
Schübeler Jets called the Vector II. The
most striking thing about this jet is the
leading edge slats allowing the profile
geometry to be adjusted during flight.
Due to the leading edge flaps the stall
speed is reduced and it enables a high
thrust-weight ratio (up to 1.2:1 with
LiPo cells) jet-like acrobatics.
At the EDF-Meeting in Gronau
measurements showed the very good
slow flying characteristics of Vector II.
They also recorded a top speed of 183 mph (295 km/h)
when using the DS-51-DIA (3 ph) moulded carbon fan
and a brushless motor running on 20 Sanyo RC-2400
NiCds. When using LiPo a much higher thrust to
weight can be achieved.
The fuselage and wing roots are hand moulded as a
single piece
from CRP, GRP & ARP, with balsa
covered foam outer panels. The winglets
are CNC milled and are screwed onto
the wing to allow removal.
The model is supplied with seamless
ducts for the DS-51-DIA (3 ph) fan, which
are almost “plug & fly”.
The wing span is 1158mm (45½”), the
length 1103mm (43½”). The flying
weight is given as 2.75kg (6 lb.) (20 RC2400 cells) or 2.25kg (5 lb.) (LiPo).
Schübeler Jets products are imported
into the UK by Al’s Hobbies, but as yet
do not appear in their website
(www.alshobbies.com). For more
details email [email protected] or
call 0208 500 8884. The kit price is £350
plus £180 for a DS-51-DIA (3 ph) fan.
More info and other worldwide dealers
can be found on the Schübeler Jets
website at www.schuebeler-jets.de
28
E.F.-U.K.
Two models from Graupner on this page.
Firstly an unusual model that is boat and
plane - the HYDROPLANE 3D.
The model resembles a typical fast racing
hydroplane design, but has 2 sets of
elevons at the tail (stern?) that are
interconnected. It also features twin air
rudders. Manoeuvrability on water is
unlikely to be brilliant, but this is a very
different model..
The Hydroplane 3D is 79cm
(31”) long, 55cm (21½”) wide
and 22cm (8½”) high. The
flying weight is around 235g
(8¼ oz.) giving a wing loading
of only 11.9g/dm2 (3.9 oz./sq.ft.)
It is quick and easy to assemble from vacuum-moulded and laser-cut Depron®
components. The reinforcing struts are lightweight, high-strength CRP profiled
strips, ensuring a low all-up weight. To complete the model you’ll want a 280
class brushless motor, a suitable 10A controller, propeller, a 3s LiPo pack between
350mA and 650mA and 3 mini-servos.
The Hydroplane 3D should be available through your local model shop or any of
the internet model shops. The cost of the kit should be around £60.
The second model is the Graupner
SPEED CAT. The Speed Cat is a pylon
racer of all-GRP construction. All the
model´s components, i.e. fuselage, onepiece wing, tailplane & wheel fairings,
are supplied ready-made moulded items,
high-gloss , painted in the mould.
The key features of the Speed Cat are
its beautifully, harmonious, lines and distinctive “apple cheeks”, which give the
model an interesting semi-scale appearance. The model is capable of very high
airspeeds, especially electric powered. The aerodynamic layout of the Speed Cat
gives the model pleasantly stable flying characteristics, and any RC pilot with
average flying skills will not find it difficult to control.
It features aileron, elevator and throttle control, has a span of 101cm (39¾”) and a
wing area of 18.8 dm2 (290 sq.in.). The target flying weight is 1.2kg (2 lb. 10 oz.)
using a 500 size brushless motor and 3s LiPo with 40A ESC. Also included are the
pre-formed aluminium undercarriage, 2 foam wheels, plastic spinner, small items,
decal sheet & linkage pack. Price around £150 from local model shops/internet.
E.F.-U.K.
29
Want a small and
inexpensive brushless
motor and controller,
then maybe the new
budget items from All
Electric RC are for you.
The motor is equivalent to a Speed 400 motor and
costs only £9.99. The controller is £15.99, rated at
10A, weighs only 10g (0.35 oz.), is a simple plug & play design and has a jumper to
select between 2s and 3s LiPo. Even better, buy the two together for only £19.99.
Check out the All Electric RC website at www.allelectricrc.co.uk for the complete
range of products. Call them on 01782 788 778 to order or for more details.
Another recent product that you might have
missed are the Saphion Lithium Phosphate cells
available from Overlander. Lithium Phosphate
(LiPh) cells are much safer than Lithium Polymer
(LiPo) & Lithium Ion (LiIo). They are only
dangerous when short circuited or put in a fire,
much the same as with NiCd or NiMH.
The only capacity available at present are 1200mAh
cells, which are rated at 15C, which is an 18A
discharge rate. According to the data, they can
withstand burst at 25C (30A). They also have the
benefit of being chargeable at 2C (2.4A) so recharging in the field is more practical.
LiPh cells have a lower terminal voltage at 3.2v/cell. Despite this difference,
Overlander stated that they can be charged using a LiIo or LiPo charger (3.6v or
3.7v per cell). They can be discharged down to 2v/cell without harming the cell.
Each cell weighs 42g, broadly the same as similar capacity and discharge rated
LiPo cells, however, the Watt-Hours are lower
due to the lower voltage.
Packs are available as 2S1P (6.4v) £16.99, 3S1P
(9.6v) £24.99, 4S1P (12.8v) £32.99 or 5S1P (16.0v)
£41.99. Packs can be parallelled (as LiIo and
LiPo) to increase capacity or discharge rating.
Saphion cells should be available from your local
model shop, or direct from Overlander. Check
out their website at www.overlander.co.uk or
contact them by phone on 0870 750 6411 or email
at [email protected]
30
E.F.-U.K.
TLC from your TLO
By Alan Bedingham
It all started when I bought a glider fuselage for my 2.5m electric Silent Dream. A
few twangs off the bungee later, I was surprised how easy it was to get away in
light lift with the glider versus the electric version. I don’t know about you, but to
me, an electric glider is for just plain enjoying the day rather than competitions.
No hassle with laying out bungees or trying to find the blasted parachute when it
drops in the long grass. The sheer pleasure of working a little bit of lift low down
and a long way off that you wouldn’t dream of trying for if you didn’t have the
electric thermal to fall back on. Competing against myself I suppose.
One guilty pleasure is deliberately circling in sink with the power on waiting for
other gliders to join me and watching them drop like stones. Tee hee! So why is
the glider version better in light lift than the electric version? Well, the obvious
answer is that it is quite a bit lighter, over 19 oz. lighter in fact. The wing loading
of the glider is 10.6 oz/sq.ft., the electric is 14.9 oz/sq.ft., some 40% higher – blimey!
The next question was - how can I get the weight down?
The setup I’m using is an Irvine 05/07 Cobalt with a 3:1 gearbox driving a 14” x
10” folder on 8 RC-2400 cells. I had an 8 cell pack of CP-1600s that was 4oz.
lighter than the RC-2400s, let’s try them. Much to my surprise, the climb (always
pretty brisk) resembled a homesick angel and I needed a bit more down trim
mixed in.
Hmm – let’s try a smaller propeller. I had a 12.5” x 10” folder in stock, so I gave
it a try. The climb was pretty good but it was obvious that saving 4oz wasn’t going
E.F.-U.K.
31
to be enough to get the glide performance I was looking for.
Changing to the smaller propeller had dropped the current from 31A to 20A, maybe
I should be looking at LiPo batteries? I’ve been using a 3S pack of 1500mAh
batteries in a Speed 400 powered Hawk for a while, but they wouldn’t give 20A,
more like 12A. Then the penny dropped – buy another 3S 1500mAh pack and run
the two in parallel.
I made up a balsa crate to fit them in the space where the NiCds used to go and
made up a couple of Y leads. Luckily, the NiCds were on the CG, so the LiPo pack
had no effect on the overall CG of the ‘plane. Weight saved so far – 10 oz, dropping
the wing loading to 12.7 oz./sq.ft., still some 20% more than the glider version.
Flying it was a revelation, the climb is back to homesick angel levels and light lift
scratching is much easier than before. Not only that but I had more battery
capacity (3Ah instead of 2.4Ah) and nearly double the power on time because of the
lower current draw! Roll on the next All Up Last Down competition!
My best flight in one of those was nearly an hour and three quarters with the old
setup, what’s possible with the new one?
It’s difficult to see where I could lose that last 9oz., maybe an outrunner would
save me about 4 of them (at a cost) and if I could find one that will swing a big
32
E.F.-U.K.
propeller on 3S LiPo and only pull 20A or so. I think I’ll leave things as they are
for now and enjoy flying a ‘plane that’s much lighter than it was.
Lessons Learned
I was surprised at the difference relatively small reductions in all up weight can
make to climb performance.
Changing an existing ‘plane to LiPo saves so much weight that you can think
about cutting the current by using smaller propellers and still have the same
performance.
Cutting the current means that you can use lower capacity LiPo packs or get
more power on time.
Next Steps
I was at the Southern Model Air Show and spotted on the RCM Direct stand a 3s
10C capable pack of 3600mAh LiPos for a very reasonable £48. Wonder if they’ll
go into my Vermont Belle? This is fitted with an AXi 2820/10 (when will
manufacturers stop using these gibberish names?) running a 12” x 6” propeller on
an 8 cell pack of RC-2400 at around 38A.
Performance is good with enough vertical for big loops and even vertical eights.
It’s only problem is that I have to limit myself to six minutes to make sure I have
enough grunt left for a go around if I need one. Still haven’t quite got the hang of
this landing lark after all these years!
E.F.-U.K.
33
The LiPo is wider than the NiCd pack so a bit of hacking and carving was need to
get it to fit. Weight saved is just over 8oz., some 15% lighter overall. I tried
different propellers with an eagle eye on the Whattmeter and settled on a 10” x 7”
that pulled 36A. Note the big change in propeller size, don’t forget a LiPo is worth
around 3 NiCds so I was effectively fitting a 9 cell pack and I also wanted to cut the
current a bit. It flew very well, the vertical is better than before and the duration
is working up to 10 minutes.
Perhaps I should explain that remark. I don’t have a single LiPo capable speed
controller, so what I do is start at a conservative flight time, like six minutes,
recharge the battery after each flight and gradually increase the flight time until
I’m putting back about 70% of the capacity.
My transmitter has separate count down timer settings for each memory which
makes this easy to do. The only problem is hearing the beeps over the noisy oily
fans! It’s a conservative approach that leaves a bit of leeway for windy days (you
always use more power on windy days, have you noticed?) and that keeps me on a
relatively level part of the discharge curve and well away from the LiPo 3V limit.
My aim with this electric lark has always been to equal or better the oily fan
‘planes. I’m there in terms of performance, in fact, when I took over a learner’s
glow model to show him how to do a proper circuit for his ‘A’ test, I was surprised
how under powered it felt compared to my electric models. Duration has always
been the bugbear, until now.
34
E.F.-U.K.
I was flying the Vermont Belle, trying out aerobatics, when I heard a glow model
start up behind me. Both of us shared the pattern until he called ‘landing’ and
brought his ‘plane in. I was still in the air! First time that has happened to me.
Flushed with success, I started looking at some other models that hadn’t been
flown for a while. My gaze lighted upon the venerable Fiasco. This had been
designed to fit in the trunk of the Fiesta I owned at the time (always known to us
Fordies as the Fiasco – just black humour - you don’t want to know what we called
the Focus) lengthways with the rear seats folded, so it is 50” wide and 50” long.
Designed as a knockabout fun model, with a symmetrical wing section, it flies just
as well inverted as the right way up. My trademark of rolling inverted just as the
wheels left the ground once attracted a ‘had a glitch did you?’ comment from one of
our members. Isn’t it nice to know your engine isn’t going to misfire or stop?
It was fitted with an Astro 25 geared swinging a 12” x 8” on 14 cells and weighed
70oz. all up. It has served me well, doing plenty of flying and surviving a few
crashes over the years. Have you noticed how long electric planes live for if you
manage to keep them away from terra firma? I reckon it’s the lack of vibration
E.F.-U.K.
35
and oil that does it. The oil because it makes them easy to repair!
It had been put on the backburner because you don’t get many charges of a 14 cell
pack from a car battery in a day and it had a distressing tendency to bend the
undercarriage if a landing wasn’t absolutely perfect. I tend to average one out of
ten landings perfect, six out of ten acceptable and the rest I don’t want to mention.
There followed a feverish session on ElectriCalc assessing the possibilities. I ended
up with the 3s 3600mAh LiPo pack and an Astro 05 geared swinging an 11” x 7”,
the Astro simply because I had one in stock. This doesn’t seem possible until you
look at one of the useful numbers ElectriCalc works out – W/lb.
The 14 cell version is 89 W/lb., the LiPo version is 103 W/lb. The drop from 410W
to 310W is more than made up for by the massive weight saving. Have a look at
the pictures, the 14 cell powertrain weighs 44½oz. including a receiver battery,
the LiPo 18½oz. (no receiver battery required), a reduction of 26oz.
The whole ‘plane is 35% lighter! Looking at the ‘plane pictures you can see how
eerily empty it appears with the LiPo setup.
Off to the flying field to give it a go. This can’t work, can it? It can! Just as lively
and aerobatic as before and with a lighter feel, more like the Vermont Belle. The
landings were like a butterfly on thistledown.
Well, you know what I mean, it’s always easier to make a landing look good with
a light ‘plane than a heavy one. So it flies just as well for longer and I can get more
flights in a day since charging the LiPo hardly dents the capacity of the car battery.
As the Americans say, ‘a win-win situation’.
Lessons Learned 2
LiPo conversions aren’t necessarily just a simple substitution of one battery for
another, you really need to think about the whole power train before and after.
You may be surprised at how much weight you can save.
36
E.F.-U.K.
Anyone
want to buy a pile of NiCds?
Velly cheap!
Readers’ Models
Your chance to show the members your model(s).
Above is the “Donald 4” flying boat of Rich Flichbaugh, South Dennis, MA. It has
a Mega ACn 22/10/6 motor, Castle Creations Phoenix 35 controller and a 10-cell
Sanyo 1300mAh battery pack. This gives ample power for up to 10 minute flights.
Below is Rich Flichbaugh with his Great Planes Piper J3 Cub float plane taken at
Scargo Lake, Florida. It features scale early design Edo “flat top” floats. A Mega
ACn 600/20/5 motor with the same equipment as above give 8 - 10 minutes. The
weight is 51 oz. (1.45kg), giving a wing loading of 15.6 oz./sq.ft. (47.6g/dm2).
E.F.-U.K.
37
These pages feature the 'Interceptor' of Mike Pirie, built from Gordon Whitehead's
plan. It certainly does! What's more it then gives a 20 minute aerobatic flight.
The original Frog ‘Interceptor’ with Mike Pirie’s model
The original 'FROG' Interceptor was produced in the 1930s and was probably one
of the world's first ARTFs. With a span of 11” it came in a small cardboard box
and comprised a fuselage, two plug-in wings, removable undercarriage and a
gearbox/propeller unit with a rubber motor. After assembly, it was wound up by
placing the fuselage in its cradle in the bottom half of the box so that the propeller
engaged with a ratchet mechanism at the front of the box, then a small handle
was inserted into the box from the outside and turned the required number of
times. With sufficient winds the model would then rise off a smooth surface to fly
for a short time - probably only for a few seconds.
Mike’s model in flight
38
E.F.-U.K.
On Finals, very graceful
Gordon's stylish model is a four times scaled up version of the original, and spans
118cm (46½”). Things have moved on a bit since the time of Gordon's plan (at
least a decade ago) and by the elimination of gearbox, receiver battery and heavy
radio gear, I succeeded in reducing the a.u.w. by a respectable 100g to 1230g
(43 oz), giving a wing loading of 54 g/dm² (18 oz/ft²).
On my model, a Fanfare Powermax 40T up front, turns a 10” x 5” APC propeller
direct drive, the energy coming from a 3s2p pack of Kokam 2000s. The motor
draws 25A (static) so I guess the power loading must be in the region of 250 W/kg
or 90 W/lb - this could explain the stunning performance!
The colour scheme is as per the original FROG model, the silver fuselage being
replicated by the use of chrome Fibafilm. The 'FROG' logo was found on the
internet and transferred on to transparent inkjet vinyl (from Overlander).
The plane is a shear delight to fly, and performs aerobatics (limited in my case)
with ease. It is difficult to avoid a bounce on the landing however, and
disappointingly it is not very willing to taxi in a straight line (it needs a steerable
tail wheel).
The only deviation from the
plan was for the battery
access which is now by
removal of the wings (one bolt
to unscrew) rather than
having an unsightly hatch on
the lower fuselage.
I also added a fibre-glass
bandage at the wing joint as
I didn't like the idea of a butt
join. And oh yes . . . I added
a pilot!
E.F.-U.K.
39
I thought that you might like to see the following photos of my fellow Guildford
Model Flying Group members’, Dave Dyer (above) and Tony Skilton (top right),
Lancasters, and maybe include them in a future edition of Electric Flight U.K.
Both models were built from the Priory Models kit using standard 6v Speed 400
motors, and 8 x 3300mAh cells - either GP 3300’s or Puffin Hi-Flow 3300’s. Tony’s
Lancaster weighs 5lbs 4ozs, Dave’s weighs a little more as he has fitted working
rudders to his model. The wing span is 6ft. Both get between 8 - 10 minutes flying
time on the 8 cell packs. Unfortunately, the only time we managed to get both of
these Lancasters in the air together, we had no camera around !!
40
E.F.-U.K.
E.F.-U.K.
41
The Electrifly PolyCharge4
by John Stennard
Every now and then modelling items appear that answer a particular need and
this charger is certainly one of them. I saw this charger advertised in American
model magazine and quickly found that not only did Tower Hobbies have them in
stock but they were at a ‘special deal’ rate. Following a phone call to a helpful lady
at Tower one of these chargers was on its way to me.
Why was I particularly excited about this charger? In common with virtually all
the flyers at our indoor sessions I never charge in the sports hall as I now have
enough cell packs to keep me flying all evening. Of course the problems start
when I get home and have about ten packs to charge.
There is no question of leaving LiPo packs connected and charging overnight so it
is a long process the next day charging all the cells. The Polycharge4 is unique as
it is actually four chargers combined in one unit. Each charger can charge 1 – 4
cells at rates from 300mAh to 3000mAh. A built in fan keeps the charger cool and
the unit is fused. The unit is packed with ‘features’ and mine works perfectly.
The charger requires a 12- 15v power source and of course if running all the
outputs at the maximum current at least a 12A required. A mains regulated unit
is obviously preferred rather than a Leisure battery to supply the charger.
42
E.F.-U.K.
Two A4 sheets of instructions cover the handling and use of the charger. Basically
it is extremely simple and as usual the only likely cause of an error would be if you
set an incorrect charge rate. After connecting the pack and setting the correct
charge rate, normally 1C, the black button is pressed. The system uses a tricolour LED to indicate certain conditions starting with the automatic cell count.
Initially a solid green LED indicates that the cell count is being checked. When
this has been done, the LED flashes according to the number of cells that the
charger has read as being present. This is a first indicator that the pack is in good
condition. Obviously an incorrect count means that a cell is malfunctioning.
When the pack is fully charged the LED flashes red and an audible tone sounds.
Again the red LED flashes according to the cell count so this is a further check on
the state of the pack. If for any reason the pack does not charge within a threehour period the charger switches off automatically and the LED flashes orange.
Included in the instructions are ‘Important Precautions’ that deal with the correct
handling of LiPo cells. These instructions are very clear and explicit and are
worth reading even if you are experienced in handling LiPo cells.
I hope this charger will soon be available in the UK from the GreatPlanes distributor
as it has certainly been one of my ‘best buys’.
E.F.-U.K.
43
Fixing Günther Propellers
by Nick Fitton
My first encounter with 2.3mm shafts was via the TwinJet. I was sceptical about
the recommended method of propeller attachment (push it on) so I phoned a highly
experienced EF guru, who shall remain nameless. He told me that a bit of spit on
the shaft and a good push was all that was needed. Indeed, he told me that he had
never had a Günther propeller come off, saying that he must have spit like epoxy!
Thus assured I flew my TwinJet with delight until one day a propeller came off at
exactly the wrong moment, i.e. the instant it left my hand at launch. I couldn't
hold the resultant asymmetric thrust and the clutching hand which is gravity
took over. Not much damage but a lot of annoyance.
I wanted to be convinced that pushing propellers on was sound practice, but my
fathers oft repeated dictum "A man convinced against his will remaineth
unconvinced still" was never far from my mind. I tried bonding the propeller on
using thin cyano, being careful to remove all traces of oil from the shaft and not to
bond the shaft to the motors front bearing. But still propellers flew off occasionally,
fortunately at non-critical times.
My next cunning plan was to drill a pin hole right through the black plastic insert
and allow a blob of gap filling cyano to flow into the insert before pushing it on to
the shaft - you have to do this quickly otherwise the cyano starts curing before the
propeller is fully home. I was convinced this would solve the problem, but there
was no improvement.
I tried the same with epoxy, poking it into the insert with a match, but whilst this
seemed better than cyano, it was only better in the sense that the propeller stayed
on longer before letting go.
As a last resort I tried high shear strength adhesive, one of those specifically
designed for fixing pinions to shafts in geared applications - and I have never had
a failure in this application. Again I was unsuccessful. Presumably these adhesives
are not designed for metal/plastic bonding, which comes as no surprise.
I persevered, but I knew in my heart that gluing propellers on was not the right
path - as Taoists would put it, it was a "path without a heart", thus one to be
abandoned. It takes a lot of pressure to force a Günther propeller on to the shaft.
I was sure that what was happening was that the black plastic sleeve was relaxing
over time, weakening its grip on the shaft.
In addition, propeller acceleration/deceleration forces would constantly test the
integrity of the bond line, as would the occasional ground contact. Cyclic thermal
stresses may play a malign part too.
Thus I was forced to conclude that all glued methods must eventually fail, and I
moved to mechanical type adapters. Here are my findings:
44
E.F.-U.K.
The Collet type
These exert an enormous clamping force on the motor shaft, and are self centring.
The ones I bought had, however, a number of disadvantages. Firstly, the relatively
large back plate fouled the back of the Günther propeller, and I don't like hacking
away at any propeller, especially one turning at 14000 rpm, even if it is very light.
Secondly, the collet was relatively massive, with a centre of gyration some distance
from the shaft axis. Any inherent vibration in the system will be amplified by
these factors, as will mounting the collet near the end of the shaft. The Speed 400
shaft is long, thin and 'whippy'.
A big advantage was that one could achieve a very small gap between nose and the
back of the spinner, which is aesthetically pleasing, but fitting the spun blue foam
spinners I use proved impossible. Sometimes collets can be difficult to remove,
such is their massive hold on the shaft.
The Grub Screw type
To all intents and purposes these too have a virtually unbreakable hold on the
motor shaft, and certainly so in the case of Speed 400 motors. Those with two
grub screws (Graupner do a lovely one) are to be preferred, if only for their
engineering excellence, more on these later.
A major disadvantage is that it is difficult to produce an aesthetically pleasing
fuselage / spinner gap. The way round this is to glue a balsa ring to the nose to fill
this gap: one might also mount the motor some distance back from the bulkhead
but this would introduce problems of lack of rigidity and high localised forces on
the mounting plate.
The Graupner propeller adapter is beautifully produced (see below), is light and
thus has low rotational inertia. It also has a bullet type nut, this feature giving us
something to which a spinner can be attached.
The spinner is spun blue foam. I make a 1/16” ply disc of the required diameter
and using double sided tape, fix a block of blue foam to it. Spin it (in a power drill
in a vice) to the desired shape and length and separate it from the ply former. This
is not needed any more, but is retained for future use.
E.F.-U.K.
45
As accurately as possible, carve the foam to receive the Günther propeller so that
the back of the propeller is flush with the back of the spinner. Using the cone
shaped rotary stone attachment for the Dremel, lightly bore into the foam, keeping
everything as central as possible.
Now the clever bit. Cover the Graupner spinner with double sided tape and simply
press the foam spinner on, using the model's nose former as a square, flat guide.
You'll probably have to experiment a bit to get it right.
A small degree of eccentricity is not noticed in practice. There is no flight load on
it, the only force being the airstream pushing it on, which is to our advantage, and
the rotating mass is so low that there is no vibration, even at 13000 rpm.
One of the features of using the Günther propeller is that spinners tend look too
large in relation to the propeller, blocking out a seemingly high percentage of the
swept area. The small Günther propeller has a diameter of 125mm. Even if a
spinner were half that at 62.5mm, which is unlikely, it would blank out only 25%
of the swept area. Actual spinners required are typically less than 40mm, blocking
out less than 10% of the disc area.
More important is the effect a large nose diameter has on the airflow leaving the
back of the propeller, so it makes sense to reduce the nose diameter to the minimum
practicable. This can be achieved by utilising the full length of the Speed 400
shaft. About 30mm diameter spinners can then be fitted. These have a mere 6%
blanking effect. It is always good practice on an aeroplane, full size or model, to
reduce everything to the minimum that will do the job.
My Speed 400 Tucano incorporating all the above best practices, built light and
with an 8 cell KAN pack has a flying weight of just over 18 ozs. It goes like stink,
has good duration and amazes the IC mob. What price now brushless / LiPo !
So far going the 'grub screw adapter' route has proved completely satisfactory. I
keep two spare complete propeller/spinner assemblies in my flight box just in case.
Propellers can be quickly and easily changed in the field should one experience a
less-than-ideal landing, not that this has ever happened to me (honest).
46
E.F.-U.K.
Wing & Wheels Model Spectacular is delighted to be able to remind Modellers that
24th and 25th June 2006 represents the 20th Anniversary of the show.
First held at North Weald Airfield in
1986, the show has evolved into one of
the most respected and popular model
shows in the UK and has featured some
of the very best models and pilots from
the UK and Europe. With its fabulous
runway facilities, excellent crowd
proximity capability and massive trade
support, Wings & Wheels has always
been able to put on a show that
spectators return to year after year.
A large part of our success has been due
to the support and participation of the
Show Pilots, helpers and their models,
the loyalty of our Traders, as well as
the many other supporting attractions
such as Modellers’ Bring & Buy, Indoor
Flying Displays, Large Model Boat Pool,
Model Car Displays and huge Saturday
Market adjacent to the Show.
Whether you are a participant of one of the above attractions or a visitor we
would be delighted if you would come to next year’s show to celebrate 20 years of
Wings & Wheels
See more about us at: www.wingsnwheelsspectacular.com
or contact the Show Organiser
Designaction Limited, PO Box 284, Huntingdon, Cambs PE28 9WT, UK.
Tel/fax: 01480 462 265. Mobile: 07836 297 168
email: [email protected]
E.F.-U.K.
47
NEAT Fair
16-18 September 2005
by John Anderson
Downsville, NY, is now firmly established as the place to be for electric flyers in
North East America on the third weekend in September. A few make long journeys
to be there, a thousand miles or so!
At this point I have to confess that some of my notes cannot be found now that I
am back at home. Accordingly not all the photos have full captions and some have
only what I can remember or given to me on a piece of paper by the modeller.
Own design sailplane by Joseph Dellutris named Rita. 4m span powered by AXI 2826-10
with 14” x 7” propeller and 2S2P 2000 mAh
48
E.F.-U.K.
Last year the meeting was washed out by 14 inches of rain in 24 hours. This year
the weather was much kinder. Most of the time it was sunshine and varying
amounts of cloud. The site opens on the Thursday for traders but also many
modellers arrive to claim a good position to pitch their canopies including my
friends from Syracuse who provide cover and seats for me.
As the weekend wore on the sun increased and by Saturday lunchtime the crowd
was four or five deep to watch the lunch time demo flights. Generally the wind
was light but being in a valley occasionally a gust would funnel through.
Each year I try to take out a model that is produced in U K. My selection is
limited to a model that can be transported easily. This year I had been playing
with a P-51D from Electro Flight.
This is basically a Depron model with a printed paper overlay. I selected the
Spitfire from the range and undertook the pasting of the printed paper to the
Depron at home. This enabled me to transport it in my checked suitcase sandwiched
between my unmentionables
Assembling the model and installing the motor, ESC, servos and links was
undertaken at my daughter’s home in upstate New York. Range checks and test
flights took place nearby and attracted most of the children (and some dads) from
the nearby houses. With the test flights completed it was off to the Fair.
A Spruce Goose from Laddie Mikulasko, span 86” and powered by 8x Speed 400 motors
each powered from 8 cells in a combination of series and parallel. Weight around 9lbs.
E.F.-U.K.
49
Beautifully built Antoinette about 6ft span.
Only a few seconds in the air before stalling
So what was new. Nothing I saw could
be described as revolutionary. The
charging of LiPos is where safety is being
given priority. “Astro” Bob Boucher has
developed the ‘Blinky’ cell balancer (see
page 23) and Kokam are charging each
cell in a series pack individually.
These two are tackling the problem from different angles although both require
each cell to have a tap to a terminal. Astro Flight Balancer is used with a charger
connected in the usual way and the balancer connected to a tap from each cell.
The circuitry looks continually at the voltage of each cell to three decimal points
and discharges the higher voltage cell(s) to reach equilibrium. Only a small number
have been made for test purposes but they should be available later this year.
With Kokam it is simply each cell being individually charged by a special charger.
The Kokam Balance Charger comes for 2 series and 3 series cells and detects
when each cell is full and shuts down the charge to an individual cell as it peaks.
A different charger is needed for 2S packs and 3S packs which makes the set up
rather expensive as they may not be suitable for other brands of LiPos. Personally
I am drawn towards the Astro gismo but before I can consider this I need to get my
3S LiPos tapped. Is this a job for a modeller or should it only be trusted to a
specialist? I look for guidance. (Editor: see my notes on page 24)
50
E.F.-U.K.
Hobby Lobby B-25 Mitchell. 19lbs 2x AXI 4130 driving 15” x 8” propellers on 6S3P
Some new models were on show, the most noteworthy from a commercial concern
being the B-25 Mitchell from Hobby Lobby. A kit should be available towards the
end of the year with pricing in the region of $500.
An exceptional model of an Antoinette was on a stand by the truck of Don Bosquet
although I am not sure that he had built it although it was in his style. Dave
Barron, the regular B-17 pilot, was recruited to test fly the model. But as you will
see from the photos the angle of climb shortly after take off was too steep and a
second or so after the photo it stalled. Repairable in the workshop where no doubt
the C of G will be examined.
The Hobby Lobby stand was decked out with about 20 models from their range,
although they had taken the decision not to sell direct. Every one who has visited
the USA will know that the price on the ticket will have sales tax added at the till.
This varies from state to state but is not applicable to sales made and shipped to
residents of other states or exports.
Hobby Lobby had taken the view that by selling at the NEAT Fair they may
become caught by the New York tax system and this would mean all sales to NY
residents would be taxed, instead of tax free coming from their home state of
Tennessee. They have been supporters of the Fair since inception and this year
provided raffle prizes for the draws on each of the three days. The star was the
Gee Bee complete outfit which had been flown regularly in the hours leading up to
the raffle. A very generous gesture as its value must be at least $1000.
There is a down side to this well attended meeting, over 250 pilots registered this
year. It is the lack of accommodation in the area. Most motels within 20 miles are
E.F.-U.K.
51
Also from Laddie this Blohm und Voss, span 50”, weight 4¼lbs, 2x S400 with 2:1 boxes
small, not more than 15 or so rooms, and are often booked up months before.
Camping is popular and there is plenty of room on the site for mobile homes and
tents. Caterers provide a good selection of food from early morning to evening.
The campers using tents can rely on sustenance without having to leave the site.
I shall go again next year, God willing, as I get 3 days away from my grandchildren!
Spectator line for the Saturday demo hour.
52
E.F.-U.K.
Balsacraft fan Edward Brimo brought three models to the Fair. Sea Fury powered by
AXI 2820-10 with 10.5” x 6” propeller and Kokam 3S1P 2100 mAh. Spitfire powered by
Phasor 30/3 and 10” x 7” propeller and Thunder Power 3S7P 3200 mAh. Bearcat
powered by AXI 2820-12 with 10” x 7” propeller and Thunder Power 4S2P 4200 mAh
This autogyro is built by Dave Ramsey based on a design of Mickey Knowles. Uses a
helicopter linkage to the rotor (kit bashed 2 sets to make up head) and set the head in
GWS gearbox. Flew nicely in the calm conditions
E.F.-U.K.
53
Here is Dave Barron with the Joe Bashir B-17 making final preparation for yet another
flight with this impressive model.
Ric Vaughn drove from Atlanta with his workshop trailer housing this enormous model.
Don’t have details but it has a floodlight system making night flying a piece of cake
54
E.F.-U.K.
Apologies to David ? This 10 year old flew a superb slot in the lunch time demo. Sorry
no details of this pattern ship but I remember that 800W was available at full throttle.
Flown by Hobby Lobby was this Funtana. Power was Hacker C50XL with 6:1 gearbox.
10S3P Tanic cells gave urge to this 9lb model
E.F.-U.K.
55
The writer’s Electro Flight Spitfire. Tweety Torque motor with Jeti 8-3P controller and
Kokam 3S1P 640mAh pack turning GWS 7” x 4.3” propeller
56
E.F.-U.K.
Perkins ARTF Tiger Moth
by John Thompson
This kit is by Green R/C Model Airplane Co Ltd made for J. Perkins, spans 50”
(128cm), and is designed for a .30 cu. in. (5cc) 4-stroke glow motor. Mine was
bought part assembled from my local model shop, where it had been in this state
for some months. The assembly appears straight forward as all the main parts
are supplied covered, even the decals fixed in place.
The tail unit is attached with two bolts from below, and here was one of the changes
I made. The kit includes a tail wheel, and I have never seen a Tiggy with one of
those, so a steerable skid was made, much better for our grass runways.
The rudder servo is coupled to an idler that protrudes through the fuselage sides to
take the closed loop wires in scale fashion. This idler is supplied made from CNC
cut plywood that did not seem very good to me, so a replacement was made out of
fibreglass circuit board (see below).
Beside the rudder servo is the elevator one and this also has closed loop connections.
I was concerned that these actually twist through 90° so a simple addition to the
tray turned the servo to be in the same plane as the elevator hinges. Both these
controls now worked in a smooth fashion and gave accurate neutrals.
The ailerons use separate servos with short rods, so were no problems here. Perkins
had included some of their own items in the contents of the kit, with an addendum
to the instructions.
E.F.-U.K.
57
These included metal quick-links with springs to secure them. I found these links
rather tight on the threaded connectors, and had one strip. The landing and
flying wires also use these links which fit into alloy angle brackets, and these
went together quite well. One thing would improve it, a moulded corrugated cover
for the centre section tank.
The electric conversion was not difficult as the deep cowling gave space under the
motor for a battery pack. This cowling is a superb light, fibreglass moulding but
there was no indication as to exactly where or how it should fit. I installed it as far
back as possible using a hardwood block below and an alloy bracket above to take
self-tapping screws. My first choice of motor was an AXi 2820/10 that I had spare,
and it was installed in a simple plywood mount with speed controller behind.
Under it a ply box was fitted tailored to fit a 3s2p 2600 LiPo battery. Access to this
is a removable panel between the undercarriage ()shown below) and the firewall
that has two Balsa rails to stop the cells from moving backwards. Scale air intakes
are used and the floor of the front cockpit was removed to allow the cooling air to
exit. With this layout the CG was too far back, so against my usual principles
lead was added to the battery box.
The motor was pulling 20A on an 11” x 7” propeller so it should fly. However the
first flight showed that more lead was needed. The model showed promise, although
full throttle was required most of the time. In true Tiggy fashion a dive preceded
any attempt at manoeuvres, and flights of six minutes were easily accomplished.
58
E.F.-U.K.
Later one of the new 18/15 outrunners from Plettenberg was tried, and this was a
little better, but pulled more amps. A new pack of 2200 LiPo from FlightPower
proved to be much lighter so needed even more weight. In the meantime I had had
the lucky escape with my Diablotin (see the last magazine) so was even more
careful with LiPo.
Looking through the specifications a new AXi was chosen to give more power and
reduce the deadweight a bit. The 2826/12 happily swings a 12” x 7” propeller and
improves the flight performance noticeably. It is now possible to throttle back and
have power to spare, and the
controls are well synchronised.
Then my local shop had some of
the new Saphion cells in from
Overlander. These are Lithium
Phospate (LiPh) cells which
promise improved safety (again
harking back to the Diablotin).
Two 4-cell 1200mAh packs were
bought. Saphion cells are only
3.2v/cell, lower than LiPo, but the
4s pack gives extra volts which
E.F.-U.K.
59
should also help. The 2p configuration and 15C continuous rating, gives 36A
maximum. Interestingly they also quote a 2C charge rate, which makes field
charging the cells more practical than LiPo.
These packs are almost twice the weight but better that than lead. A small battery
box mod and they fitted snugly. So that I could use the individual packs in smaller
models 2mm gold connectors were fitted, and 4mm parallelling adaptors made.
The CG came out dead on without the lead, and the Tiggy will now leap into the
air and do consecutive loops with ease. This means scale speed is now half throttle,
and ten minute flights with power left to taxi back. I could still experiment with
different propellers but it all works fine so what’s the point if the model flies well?
It is now a pussy cat to fly and has the presence of the full size as long as you do not
open the taps.
My model weighs 3lb. 10oz. (1.64kg) without batteries, about the same as the IC
version without fuel. BatteriesR/C Smart
FlightPower
Saphion
LiPo
LiPo
LiPh
2600
2200
1200
3s1p
3s1p
4s2p
6.2 oz. (174g)
5.0 oz. (141g)
12.3 oz. (348g)
So Saphions are heavier than LiPo, but safer, lighter than NiMH - time will tell.
60
E.F.-U.K.
A Smarter Dart
by John Stennard
I’m going to begin with some background information before launching the Smarter
Dart. I am a committed electric flier with a particular interest in indoor flying
and as a result also organise the indoor flying sessions for our club. As part of my
indoor interest I write monthly features for two model magazines and this combined
with my club involvement, has resulted in a constant search for a model that can
be flown as an indoor trainer but also be enjoyed by flyers with more experience.
I regularly fly in different sized venues that vary from a one basketball court gym
to a five badminton court sports hall. At last believe I have found a model that can
be flown comfortably in the smallest to the largest hall and put a smile on any
flier’s face. Before going into details I think it is worth spending a short time
looking at the requirements of an ‘indoor’ trainer.
Firstly it needs to be easy to fly and relatively impact proof. Outdoors the ‘impact
proof’ requirement does not rate the same importance as indoors where floor/wall/
ceiling impacts (plus the occasional mid-air!) are a constant hazard. A light wing
loading is essential to enable the model to be flown slowly plus enough power to get
out of trouble. A suitable model combined with a good power system should benefit
from a high power/weight ratio. A ratio of 2:1 is easy to achieve using the correct
motor/battery combination and will provide a high degree of agility.
Agility is extremely important when flying in smaller spaces and can frequently
save models from collision damage. A reasonable duration is need never a problem
and anywhere between 5-10 minutes is easily obtained and perfectly adequate. In
fact in crowded venues you might be unpopular if you stayed aloft for much longer.
Most electric enthusiasts now accept that while many models perform perfectly
well, or are even particularly suited to brushed motors and NiCd/NiMH cells,
indoor models are at their best when combined with brushless motors and Lithium
cells. The model I am writing about in this feature is powered by a low cost,
brushless motor and flies extremely well using a 2s1p LiPo pack. The GWS IPS
system is suggested as an alternative but I’m personally only interested in fitting
the optimum power system.
Now let’s take a look at the model. Paul Cook produces a number of excellent
plans for electric enthusiasts. These are all small high performance electric powered
models, and the plans are extremely well drawn and printed. Paul’s plans are
available direct from him at [email protected]
One of Paul’s plans is for an enlarged RC version of the rubber powered BMFA
Smart Dart and is called the Smart Dart ‘XS’. His model has a 560mm (22”)
wingspan and weighs around 125g (4.4oz.). Paul’s first version of this model has
a 3mm (1/8”) balsa fuselage and built up wings, tailplane and fin using different
widths of 3mm strip balsa. The flying surfaces are covered in lightweight film
E.F.-U.K.
61
and the model uses rudder and elevator
control. I was quite surprised when Paul
told me that his model hovers well but this
was confirmed by a photo of him and his
model and I’ve since proved it very
convincingly for myself.
The arrival of our indoor season coincided
with a gap in my ‘model reviewing’ schedule
so I decided to build a Smart Dart ‘XS’
myself. Anticipating that I would build
this model I had already purchased one of
Paul’s ‘Aircraft-World’ type CD-ROM
conversion motors (right).
Paul’s motors are ready to run and at the time of writing cost just £16. Searching
in my building material storage boxes soon revealed a deficit of 3mm balsa but a
surplus of 3mm Depron foam.
I was about to abandon the project until I had a chance to restock with balsa when
I realized that I could substitute Depron for balsa on the flying surfaces. Without
the natural rigidity of the balsa framework I would have to use some CF strip for
strengthening but otherwise there seemed to be no problems. Using foam allowed
me to build the model in a couple of hours.
The fuselage was built exactly as per the plan complete with undercarriage and
motor and 3mm Depron used for the wings, fin, rudder, tailplane and elevator.
The only modification I made was to use a straight trailing edge on the elevator to
keep this parallel with the front edge and give some additional strength.
The wing leading edges required stiffening and I used a very convenient 3mm half
round section strip of CF rod obtained from Woolmer Forest Composites. Flat
3mm CF strip or even 3mm square balsa or spruce could be used. The half round
CF on the leading edges did affect the C of G but I’ll come back to this later.
Apart from the wing leading edges the only other strengthening was a length of
3mm CF strip on the rear edge of the fin and on the front edge of the elevator. 3M
Blenderm™ tape (left)
hinged the control surfaces,
coming from OnlyRC. This
firm sells this excellent tape
at a price much lower than
you will pay in the chemists
and in three different
widths. The wings were
joined with epoxy and no
dihedral braces were used.
62
E.F.-U.K.
With the model assembled I soon found that I would have to move the servos from
the position shown on the plan to achieve the correct C of G. The foam wing with
the CF on the leading edges had made the model nose heavy. However it was quite
easy to move the 4.4g Titch servos from Perkins rearward to enable the correct
CofG to be achieved. A bonus here was that the control rods would be very short.
The length of the lead from the controller, a Phoenix 10 from Castle Creations,
and the length of the servo leads established
the position of the RX, this was then held in
place with Velcro. The battery location,
again using Velcro was established near the
CofG as this allows different weights of pack
to be used with having to move the battery
pack too much in either direction.
I was delighted to find that the Smart Dart
weighed just 100g (3.5 oz.) without a battery
pack. I had three sizes of 2s1p LiPo packs
available to try and these were a 310 mAh
pack from WES-Technik, a 350 mAh Kokam
pack from Robotbirds and a 450 mAh E-Tec
pack from Puffin Models. These weighed
19g (0.67 oz.), 22g (0.78 oz.) and 25g (0.89 oz.)
respectively.
E.F.-U.K.
63
So with my lightest pack my depron
Dart had an AUW of 119g (4.25 oz.)
and with the heaviest 125g (4.5 oz.).
Initial flights were made using a
GWS 7” x 5” propeller but I later
changed to the APC 8” x 3.8”
propeller recommended by Paul for
this particular motor.
I very quickly found that the Smart
Dart ‘XS’ is a delightful model to fly
and our one basketball court gym
provided plenty of space. It can be
flown safely in different ways, slow
or fast level flight, slower flight with
medium alpha attitude or very slow
extremely high alpha ‘hovering’ flight. The design of the model with its ample
dihedral makes it very stable and with Paul’s motor and a 2s1p pack it will hover
easily and perform loops from level flight.
In fact it is one of the easiest models I have flown in hovering flight. It will roll,
somewhat reluctantly, but rolls off the top of a loop more easily. Considering its
‘specs’ I think that the Smart Dart ‘XS’ has an absolutely amazing performance.
64
E.F.-U.K.
With some expo and reduced movements on the control surfaces I think this model
would make an ideal trainer. However well past that stage you might be it’s still
great fun to fly and ideal for multi plane flying where you might not want to risk
your best 3D model.
My opinion was shared by the other regular club indoor flyers especially those on
the same mode who had a go on the sticks. The enthusiasm shown was such that
this model is likely to become the recommended model for anyone who wants to fly
in our rather restrictive one basketball court flying space. A ‘standard’ model like
this would be perfect for fun events like Limbo and I know the Smart Dart ‘XS’
population in our club is about to increase rapidly.
I found that while the 310 mAh battery pack was perfectly adequate for general
flying and offered the lowest weight. The 350 mAh or 450 mAh packs are preferable
if you want to spend a lot of time looping and hovering. The 450 mAh pack gives
a 20 minute plus duration.
Personally I like to decorate even functional models, particularly if they are made
from white foam, so I applied some simple but eye-catching colour to my Smart
Dart ‘XS’. I used felt pens for the layout and acrylic paint for filling in.
E.F.-U.K.
65
Delighted with my foam
version I got in touch with
Paul to praise his design
and found out from him
that a plan for a foam
version
was
now
available.
After seeing how well my
foam Smart Dart ‘XS’ flies
I am going to now build
the balsa version. If
covered with translucent
film I think it will look
particularly attractive in
the air when the open
framework will be visible.
If you are looking for a
cheap, multi-role, indoor
model with a sparkling
performance look no
further than Paul Cook’s
Smart Dart ‘XS’.
Contacts
Paul Cook
[email protected]
Flight Line Plans, Bourne
Court, Ragged Appleshaw,
Andover, Hants, SP11 9HX
Puffin Models
www.puffinmodels.com
Tel 01454 228 254
Robotbirds
www.robotbirds.com
Tel 0208 841 7873
OnlyRC
www.onlyrc.com
Tel 01702 477 626
Woolmer Forest Composites
www.woolmer.co.uk
Tel 01428 712 126
66
E.F.-U.K.
Intermodellbau 2005
by Dave Chinery
As models shows go, the Americans have the quaint impression that their Toledo
model exhibition is the biggest. In fact the annual Intermodellbau show at
Dortmund in Germany is much bigger, with just the aeroplane hall, by itself,
outsizing the Yanks!
This year’s show was open from the 13th – 18th April, and was attended by a large
number of British modellers. Although the state of the German economy and the
Euro means the knock-down prices of a few years ago are no more, the show’s well
worth attending for the huge variety of models and accessories, either new, or
never seen in the UK.
The show is even easier to get to now! We used to drive over – it’s about 400 miles
from West London via the Tunnel, and the BMFA have organised coach/hotel
packages for those who won’t drive. However, from this year EasyJet have a
twice-daily service from Luton direct to Dortmund Airport, just a bus ride from
your hotel, and this year’s fare was only £31 return, booked well in advance!
Marble halls!
The huge exhibition complex is right next to the stadium of the famous Borussia
Dortmund football club, and hotels are within easy walking distance of the doors.
As usual, this year’s show occupied eight halls, the largest of which, Hall 4, is
dedicated to flying models of all types. The smallest hall, 2N, is still big enough
for the indoor flying demonstrations, with Shock Fliers doing rolling loops through
the roof girders!
Of the rest of the site, Hall 1, the original Westfalenhalle, is full of model boats,
Hall 2 is mainly model cars and fire engines, and Hall 3 contains a big indoor R/C
car race-track and spectators bleachers.
This year, a new Hall 3N contained a separate Computer and Games exhibition,
with free entry from the Modellbau. Halls 5 and 6 are mainly devoted to R/C cars
E.F.-U.K.
67
and trucks, with a big arena full of 6ft-long artics and scale model contractor’s
plant, the latter shifting piles of dirt from A to B then back to A again – whatever
turns them on! The Germans are into this in a big way, with many models
featuring miniaturised real hydraulic systems.
Hall 5 also contains the Conrads stand – a magnet for modellers and electronics
buffs of all types. Conrads is the German equivalent to Maplins, except that it
carries an extensive range of model products as well. The stand is set up like a
supermarket, through which a densely-packed line of customers shuffle. The bins
of goods contain a vast range of items, from solder to epoxy to assorted model
wheels, and usually cheap servos. This year, I bought good quality standard
servos with accessories, for a mere • 4 each!
Halls 7 and 8 are for railway fans, and the latter is filled with enormous layouts
from societies all over Europe. They even lay on little “play” layouts for the younger
visitors to have a go! Another branch of the hobby, which I saw for the first time
this year, was a stand selling a construction system for design-your-own miniature
roller-coasters. Loops, spirals and “stall turns” can all be included in your own
table-top “white knuckle” ride! Helps to cover the ups and down of the German
economy, I suppose!
Plane speaking!
Hall 4 is the one I spent most time in, looking at the myriad models and accessories
on sale from all over Europe. As usual, most of the models, kits, ARTFs and
accessories on offer are seldom seen in the UK. With the German economy in
decline, the “good old days” of super-cheap prices have gone, along with traders
like Langnickel, and many smaller vendors like WeMoTec can no long afford to
have stands at the show, but their wares are available from some of the retailers
still at the show. All the major manufacturers like Graupner, Robbe, Simprop,
Aeronaut and Jamara had display stands at the show, but there were no real eyecatchers in the way of revolutionary new models, except for the latter (see below).
Simprop were showing their “TurnLeft” pylon-racers, which suit the new F5D
rules, together with their existing trainer pair of Pilatus PC-9 and Harvard 1.
Dortmund 2005 Hall 4
68
E.F.-U.K.
They also showed a badge-engineered
version of the SuperNova charger with,
according to them, more advanced
features including Lithium programs.
The colourful Hollein stand had its usual
selection of kit-build models, and this
year showed an all-moulded Speed-400size pylon racer, the Voodoo.
Graupner showed a range of new models,
smallest but not least was a tiny Junkers
52 trimotor park-flyer. It looks the
picture for those able to combine a calm
day with short grass, although the little
model could obviously be hand-launched.
Among the smaller manufacturers,
PAF Modell has its usual range of ARTF
models, ranging from big gliders to
electric scale types. These included a
nice Grumman Albatross and two sizes
of PBY Catalina seaplanes. Franken
Modellbau have been previously
associated with sport and scale type
models. My big P-47 Thunderbolt came
from the range, but this year their stand
was almost monopolised by electric and
conventional soarers.
FVK Modell occupied their customary
place in a corner of the hall, and, in
addition to their well-known range of
high-tech soarers like the “Simply the
Best”, “Organic”, etc, offered a new
electric sportster, the ROCCO-M. With
a sleek moulded fuselage and plug-on
wings, it really looked the part of a light
yet manoeuvrable Sunday flyer. This
model was right up my street, but I
resisted as I already have too many
airframes (wanna buy a Brabazon?).
However, clubmate Tom Lambert
succumbed (see photo left) and his was
completed in record time and flies a
treat! Another model I did like was a
E.F.-U.K.
69
large (about 70” or 1.7metres) Zlin
Acrobat, reminiscent of my own-design
“Czech-mate” but bigger. This was seen
on the Jamara stand, but this was a nonretail display and I couldn’t find one
among the retail sites.
Elsewhere in the hall, the legendary
Batt-Mann was doing his usual roaring
trade, with customers scrumming five
deep to get to his counters (photo taken
moments after the doors opened).
I found some of the excellent new
GP1100 cells, which will be essential
this year for me to remain competitive
in the E-400 competition. The same size
as the old Sanyo 500ARs, these new cells
pack over twice the capacity while
having a much lower internal resistance
than the KAN1050s I bought last year.
(Since using these new cells, the climb
rate of my model has been transformed
– but I don’t know how long the “hot”
4.8V Speed 400 Race motor will last!)
I have been used to seeing the Ramoser
VarioPROP stand (right) at successive
Dortmund shows, but have never
previously been tempted to buy one.
However, this time, I bought a 3-bladed
unit with the “Harvard 2” in mind. It’s
difficult to match motor load and model
performance when changing from a 2bladed propeller to a 3- or 4-bladed, so
the adjustable pitch feature of these
ingenious propellers would give me a
considerable “fudge factor” to play with.
Ramoser produce propellers in various
size ranges and with from two to five
blades! They even produce forked metal
roots to take standard 8mm folding
propeller blades, allowing a very wide
range of sizes to be assembled. Adapters
are also available for standard spinners.
70
E.F.-U.K.
As usual, about 30% of the hall was
taken up with models on display, ranging
from huge model airliners and rare
military types, to daringly-decorated
“Funky Chicken” models. In contrast
with the up-to-date stuff, there was an
extensive display of vintage & veteran
models with gliders, rubber models,
compressed-air, and i.c. types. The
usual selection of “wacky” models with
7 wings and 3 undercarts were there too.
Making an exhibition!
This year’s Dortmund show was
technically very interesting even if the
prices were no great shakes. It was easy
to see that the German economy is no
longer buoyant, which was reflected in
the smaller number of stands (Editor:
and the comments of the traders).
Notable absentees were Oliver
Wennmacher’s WeMoTec and Airworld,
however, product from both these
sources were available elsewhere in the
hall. Unfortunately the exhibition is not
improving with time, we’ll have to see
how things fair.
However, using the EasyJet route makes
it much more accessible than hitherto.
This saved a day travelling and also
saved a night in the hotel. (Editor: Dave
didn’t mention that the cost was less
than the fuel and fery or tunnel costs.
The only restriction is you are limited
in what you can bring back and you
can’t stop at Aucan or the Wine
Merchant’s before the return crossing.)
I’m definitely going again next year!
(Editor: Me too!)
E.F.-U.K.
71
Electric Flight Calendar
If you would like details of your event to appear in these pages please send full
details to the Editor EF-UK, contact details on page 4. Please bear in mind that
this magazine is quarterly so ensure that the details are sent in good time.
For last minute information on events please check out the events list on the
BEFA website (www.befa.org.uk). Dates, times and, even, locations of events
can change at the last minute. You are strongly advised to check on events with
the given contacts before setting out on your journey to any event.
All BEFA flying events require proof of BMFA (or equivalent) insurance
and an ‘A’ Certificate to fly. For fixed wing models, any of the fixed wing ‘A’
certificates are acceptable. For helicopters, a helicopter ‘A’ certificate is required.
All flying models must have been satisfactorily flown at least twice
since build or repair before flying at a BEFA event.
NO TEST FLIGHTS ON THE DAY
January 2006
1st
The Brighouse Vintage MAC have been using the small airfield at
Tockwith, near Wetherby, Yorkshire for several years, but have
recently had noise problems. The field is now all electric and any
BMFA Member is invited to fly there on the First Sunday in each
month from 10 to 5pm for a small fee. Do not be put off by the 'Vintage'
part they fly anything! There is a concrete runway available and
details of the site can be had from Derek Haviour on 01422 204 472.
14th
BMFA Northern Area Indoor RC Flying at the Garforth Squash
& Leisure Centre, Ninelands Lane, Leeds, LS25 - off the A63, LeedsSelby Road. Flying from 2pm to 5 pm. Separate slots for Slowfly,
Aerobatic, Scale and Helicopters. Sub 350 and equivalent brushless
motors only. Any legal frequency. Proof of BMFA membership
essential. No free flight or IC. Spectators £1 on balcony, Pilots £5.00
(Juniors £2.00). Contact John Thompson on 01924 515 595, or email
him at [email protected]
14th
North London MFC Indoor R/C Meeting. Fixed Wing 225g max,
Heli 400g max. 6pm to 10pm. Furzefield Sports Centre, Potters Bar.
(J24, M25). Contact Peter Elliott on 01707 336 982.
14th
Waltham Chase Aeromodellers Indoor RC Meeting. 7 to 10pm.
Havant Leisure Centre, Havant, Hants. Call Alan Wallington on
01489 573 141 or Chris Carr on 0238 043 7805 or check out
www.wcaero.fsnet.co.uk
72
E.F.-U.K.
22nd
Black Lion Indoor Fun Fly. 10am to 5pm. Black Lion Leisure
Centre, Gillingham, Kent. Contact Brian Millgate on 01634 570809
or Neville Legg on 01795 877 918 or at [email protected] or see
www.medwaymfc.co.uk
February 2006
5th
The Brighouse Vintage MAC - see 1st January for details.
11th
North London MFC Indoor R/C Meeting. See 14th January.
18th
& Leisure Centre. See 14th January
18th
Waltham Chase Aeromodellers Indoor RC Meeting, see event
on 14th January for details.
22nd
Black Lion Indoor Fun Fly. See 22nd January for information.
March 2006
5th
BEFA 2006 Annual General Meeting & Traders’ Fair at the Royal
Spa Centre, Leamington Spa. See page 6 for more information.
5th
The Brighouse Vintage MAC - see 1st January for details
11th
18th
& Leisure Centre. See 14th January
18th
Waltham Chase Aeromodellers Indoor RC Meeting, see event
on 14th January for details.
19th
Impington Village College Indoor Meeting. 9am to 5pm – Fly
All Day. Including Bostonian Comp and Separate RTP Hall. Impington,
Nr Cambridge. Contact Chris Strachan on 01223 860 498 or at
[email protected]
April 2006
2nd
8th
May 2006
7th
June 2006
4th
Hayes & DMAC West London Fly-in at Cranford Park, Hayes.
More details to follow.
E.F.-U.K.
73
4th
24th - 25th Wings & Wheels at North Weald Airfield, Nr Epping, Essex, CM16
6AA. Email [email protected]
July 2006
1st - 2nd
BEFA Middle Wallop Fly-In. Possibly the largest electric event in
the UK. The Saturday is shared with the League event. Only even
35MHz frequencies can be guaranteed as available, but it is planned
that the odd frequencies not in use by the league event will be also
available. On the Sunday all 35MHz frequencies will be available.
More details to follow.
2nd
Ebor Silent Flight meeting on the York Racecourse.
2nd
9th
Chester "Roodee" Electric Fly-In.
August 2006
6th
18th - 26th 2006 FAI World Electric Flight Aeromodelling Championships
for classes F5B and F5D in Pitesti, Romania. For more details contact
Mihail Zanciu at [email protected] or Marius Conu
[email protected]
September 2006
3rd
The Brighouse Vintage MAC - see the event details on the listing
on 1st January.
October 2006
1st
November 2006
5th
BEFA 2006 Technical Workshop & Traders’ Fair (provisional
date) at the Royal Spa Centre, Leamington Spa, Warks. All the
usual fun of the fair.
5th
The Brighouse Vintage MAC - full details of this regular event on
the 1st January listing.
December 2006
3rd
74
E.F.-U.K.
FOR SALE / WANTED
Member's Sales & Wants
The items below are for sale by Trevor Wain, contact at [email protected]
or on 01332 792 508.
• Puffin Models Elegant, 2.6m glider / electric glider. Flown twice, but
other interests took over - no equipment fitted. Offers around £100.
• Kontronik Smile 40-6-18 opto, brushless, speed controller, 40A 624V with Kontronik 4mm silver connectors on the output and Schulze 3.5mm
connectors on the input and has been used twice. He would like to exchange
for the same or very similar with BEC or sell for £65.
Neil Stainton is selling the following items. All are plus postage or can be picked
up from Leamington Spa. Contact Neil Stainton on 01926 314 011 or email him at
[email protected]
• Schulze 6-636+ 8A charger for 1-36 NiCd / NiMH cells & 1-11 LiPo cells.
V8 software: £179
• New Blade Runner indoor helicopter, including 27Mhz R/C, LiPo
battery & charger: £49
•
•
•
•
Hornet Helicopter FP VGC, with carbon blades: £35
GWS PG03 gyro: £19
Blue Arrow 4.3g servos, new, boxed £8.95 each
Blue Bird 3.4g quality micro servos with coreless motor £11.95 each
Jim Horne has a WeMoTec Midi-fan with Aveox 36/24/2 sensorless brushless
motor for sale - £70. Email Jim at [email protected] or phone 01388 819 638
For Sale by Martin Collins. Contact Martin by email or telephone on 01908 583
545 (Milton Keynes). Can be picked up from me in Milton Keynes
• KYOSHO T-33 in Thunderbirds aerobatic colours. Comes with the motor
& fan unit installed (I was told it was a WeMoTec fan but I cannot confirm
that). Good condition apart from a couple of the decals missing. Price is £60
(no offers).
• RIPMAX ARTF SPITFIRE fitted with AXi 28/20/10 and model motors
brushless controller. The Spitfire has 2 mini servos in it (aileron/elevator) and
comes with an 8 cell 2400 Sanyo pack and 11" x 7" propeller. Just fit your
receiver to make it a flyer, selling due to house move and other projects it has
only 6 flights from new on it, price is £200
E.F.-U.K.
75
Neil Stainton wants a Highlight Electric Fuselage, any condition. Contact Neil
at [email protected] or on 01926 314 011
Peter Vivian would like to contact any others in his approximate area (Camberley,
Surrey) who are also new to Electric Flying, with a view to mutual assistance and
support. Peter returned to model aircraft fairly recently after a 55-year break,
with an interest mainly in building and experimenting (definitely NOT ARTF!).
He would like to meet up with others having similar interests. Contact Peter by
email at [email protected] or on 01276 21 304
Wanted by the Editor, any of the following (see page 4 for contact details):
• General / Technical Articles.
• Hints & Tips.
• Product Reviews.
• New Product notifications.
• Electric Flight Event Reports.
• Photographs of your models.
• Other items of interest.
Please send colour Digital photos or photographic (6” x 4” or bigger) prints to
the editor. Please do not send inkjet prints as too much quality is lost during
the printing and scanning process. If you have no way to write the files to a
CD, contact the Editor for other options.
Photographic prints supplied will be returned, unless specified otherwise (as
long as you give a return address).
Digital photos should be sent at the highest resolution possible, in colour, and
preferably uncompressed. Where compression is unavoidable the camera should
be set to the lowest compression possible. Photographs can be emailed to the
Editor at [email protected]
Readers want to know what equipment is fitted to models so they know what
combinations work well. Therefore please include as many details of the models
in the photographs as possible, but ideallt at least span, power train, battery
used & flight performance.
Where articles are produced on a wordprocessor package, please include an
electronic copy - it make the Editors job much easier and quicker. Ideal formats
are Microsoft Word (any version), Works wordprocessor, WordPad or Notepad.
Other formats can be accommodated, but please contact the Editor first.
76
E.F.-U.K.
New to ELECTRIC FLIGHT?
START HERE . . . . .
You may be taking up Electric Flight for the first time or you may be converting
from another discipline. Whatever your situation, help and advice is available.
BEFA has prepared an information sheet which details further sources of
information which you may find useful when just joining the hobby. To receive a
copy, please send a Stamped Addressed Envelope (S.A.E.) to Robert Mahoney,
address on page 4.
BEGINNER'S GUIDE
A Beginner’s Guide to Electric Flight is available, which explains many of the
‘Mysteries' of Electrics’ and will, hopefully, set you off on the right foot. Please
send £3.00 per copy required to The Editor of EF-UK at the address on page 4.
Please add £1.00 extra for overseas postage and remit in Sterling. Cheques should
be made payable to BEFA.
TECHNICAL HELP SERVICE
Technical help is now available again for the use of all members. We regret that
no telephone service is available, but all questions in writing (or email) will be
answered by our Technical Liaison Officer (TLO). Please refer your queries to our
TLO, to the postal or email address on page 4. If sent by post, please ensure that
you include an S.A.E. for a reply.
CONNECTIONS SERVICE
Requests are frequently received from members who wish to be put in contact
with other members living in the same area. The easiest method of doing this is
to place a free 'wanted' advert in the classified section of this magazine.
Alternatively, a request may be made IN WRITING to the Membership Secretary
who is allowed to divulge such information to members ONLY. Please supply as
much information about your location as possible and please remember to include
an S.A.E. for your reply.
B.E.F.A. MEMBERSHIP
Membership of the Association is open to all. Those who are not members of
BMFA (our national controlling body) will have a subscription to EF-UK membership
with none of the other benefits. Overseas members are very welcome and will be
classed as full members if they belong to their own national controlling body.
CONTACT
For full details, please send an S.A.E. to the Membership Secretary (address on
page 4) requesting a membership application form. Those with Internet access
may visit the B.E.F.A. website at www.befa.org.uk where you will find all the
membership information you should require and a application form.
E.F.-U.K.
77
B.E.F.A. Sales
BEFA Round, Coloured Rub-down Decals - Ultra-thin & light - 50p each
EF-UK Back Issues - Issues 71 to 73 and 75 to 81 are available to BEFA members
at £3.00 each, or £5.00 each to non-members. These prices include UK P&P,
overseas rates on application. Reprints of earlier issues may be available to special
order at slightly higher cost, contact the Editor for details (see page 4).
EF-UK Index. A comprehensive index of EF-UK, from issue 28 to date, is available
by sending a £1 coin to cover copying and postage cost.
Binders:- are available to hold 8 to 12 issues of Electric Flight U.K. Produced in
dark blue with gold lettering on the spine, these cost £4.50 each including U.K.
postage. Please add £1 for European postage and £2 for Worldwide postage.
Please send all orders to The Editor of EF-UK at the address on page 4.
Sweat Shirts & Tee-Shirts: Stock of these is now almost all gone - please
contact Robert Mahoney regarding remaining stock, sizes and prices.
PLEASE REMIT IN STERLING ONLY,
WITH ALL CHEQUES MADE PAYABLE TO B.E.F.A.
Advertisers Index
BEFA Sales ................................................................. 78
Fanfare.............................................. Inside Back Cover
For Sale / Wanted ....................................................... 75
New-2-U ............................................................. 25 to 30
RC Groups / E-Zone ......................... Inside Front Cover
Traplet ............................................Outside Back Cover
Wings & Wheels Model Spectacular .......................... 47
EF-UK advertising rates are £25 per inside or outside cover page,
£20 per full page, £10 per half page, all per issue.
Contact the EF-UK Editor for more details (see page 4).
78
E.F.-U.K.
– MAIL ORDER –
SPORTS ELECTRIC FLIGHT
FANS AND GEARBOXES
www.fanfare.f9.co.uk
GEARBOXES
FANS
Morley ‘Jet Elec’ Fan .............................. £15.00
WeMoTec Micro-Fan (280/300/330) ..... £14.00
WeMoTec Mini-Fan (400/480) ............... £28.00
WeMoTec Midi-Fan (540/ 600/930) ....... £38.00
MOTORS
MPJet Brushless motors; 9 motors; outrunners,
inrunners & geared; 280 to 700 .... £37.00 to £58.00
WEP Turbo 10 ....................................... £55.00
Fanfare Silver 16T & 20T ...................... £34.00
Fanfare Powermax 40T ........................ £38.00
Speed 600 8.4v BB SP .......................... £17.00
Speed 600 8.4v Race ............................ £22.00
RE 380 / Rocket 400 ................................ £5.00
Speed 480 BB ........................................ £21.00
Pro 400 .................................................... £5.00
Pro 480 HS ............................................... £6.00
Pro 480 HS BB ......................................... £8.00
MAXCIM BRUSHLESS
Max Neo 13Y 1430 rpm/v ................... £160.00
Max Neo 13D 2470 rpm/v .................... £160.00
Maxu 35D, 21 Cell Controller ............... £140.00
Maxu 35C, 25 Cell Controller ............... £180.00
Superbox 1.6 to 4.28:1 ......................... £50.00
Monsterbox 4 to 6.8:1 .......................... £60.00
Motor Mount ........................................... £12.00
Master Airscrew - 2.5, 3, 3.5:1 ............................. £18.00
MP Jet Planetary - 3.33 & 3.8:1 - 400 / Pro 480 ...... £28.00
MP Jet Planetary - 3.33 & 3.8:1 - Speed 480 ........ £28.00
MP Jet Planetary - 3.33 & 3.8:1 - 540 / 600 ............ £28.00
MP Jet Plastic BB - 4 & 5:1 - 280 / 300 ...................... £8.00
MP Jet Plastic BB - 3, 3.5 & 4:1 - 400 / Pro 480 ......... £8.00
MP Jet Plastic BB - 2.33, 3.5 & 4:1 - Speed 480 ..... £10.00
MP Jet Plastic BB - 1.75, 2.33 & 2.8:1 - 540 / 600 .. £15.00
Mini Olympus ............................................ £8.00
Olympus ................................................. £12.00
MOTORS / GEARBOXES
Speed 400 FG3 ..................................... £17.00
SpeedGear 400 4:1 Inline ...................... £38.00
SpeedGear 480 3.45:1 .......................... £55.00
SpeedGear 600 2.8:1 ............................ £52.00
SpeedGear 700 2.7:1 9.6v .................... £70.00
SpeedGear 700 Neo .............................. £92.00
Mini-Olympus & RE380 .......................... £12.00
Olympus & 540 ...................................... £19.00
Jamara 600 2.9:1 ................................... £24.00
Jamara 650 2.9:1 ................................... £26.00
PROPS
M.A. Folding
M.A. Wood Electric
CHARGERS
Speed 1 Pulse / Pk
Det 4-8 cells ........................................... £27.00
Speed Ex Digital
as above with discharge ...................... £55.00
Simprop 25 cell .................................... £100.00
Wheels, Wire, Servos, Fuses, Caps,
Powerpole, 4mm & 2mm gold conns.
Carbon Folders
(Perkins)
Slimprops
APC Electric
(full range available)
12x8 ................ £14.00
15x12 .............. £15.25
10x6/10x8 ......... £4.00
11x7/11x9 ......... £4.25
12x8/12x10 ....... £4.50
13x8/13x10 ....... £5.00
7x4 .................... £6.00
8x4 .................... £6.00
11x8 .................. £9.00
8x4, 8x6, 9x6 .... £3.50
5½” - 12” dia . £3 to £4
13 ” - 20” dia.£5 to £15
Selection of Graupner & Aeronaut
folding & fixed props.
FANFARE • 18 HILLSIDE ROAD • TANKERTON • WHITSTABLE • KENT • CT5 3EX
‘Sports Electric’ Helpline - Phone / Fax: (01227) 771331 - E-mail: [email protected]
Now online at - www.fanfare.f9.co.uk