Turbines Ltd www.wren-turbines.com Phone: +44 (0

WREN
Turbines Ltd
www.wren-turbines.com
Phone: +44 (0) 1709 300290
e-mail:[email protected]
UNIT 13
Century Business Centre
Manvers Way
Rotherham
South Yorkshire
S63 5DA
ENGLAND
WREN TURBOCOPTER
Conversion of ‘Century Predator’
Issue 2 – 16/11/05
To convert the ‘Predator Max 90’ to turbine
power there is NO requirement to modify any
parts – some parts are, however, omitted or
replaced with Wren parts.
Build your ‘Predator Max 90’ to the Century
instruction manual, but omitting the following
items: Engine & mounts, Vertical front frame
& screws (Op 31), front lower frames & fuel
tank (Op 31 to 36), Rear lower frames, X-frame
& standoffs (Op 37), Cooling fan shroud (Op
49 / 50), Landing gear frame & struts (Op 64),
Front end of tail support struts (Op 90)
Build Stages
There are four build stages, each of which can be pre built by
‘Wren Turbines’
1. Gas generator engine kit.
2. Assembly of gearbox on to engine.
3. Assembly of engine/gearbox into mounting frames.
4. Fitting of ‘Stage 3’ into helicopter chassis.
CENTURY PREDATOR – Stage 2 – Engine/Gearbox
Oil filling point
Dummy spacer
Tunnel lubrication fitting
Gearbox as supplied. Please note that it is supplied
EMPTY, 15ml of ‘Hypoid 90’ gear oil should be added
before use, preferably after fitting to helicopter. It is fitted
with an extended elbow to facilitate lubrication to tunnel
bearings. A dummy spacer is also fitted in place of the
power turbine wheel. The two tapped holes in the rear face
of the gearbox are for mounting the gearbox support, and
are through holes. Oil may therefore leak out if the screws
are removed.
Wrap exhaust wadding (136) round tunnel and secure with
adhesive tape (139).
Fit exhaust (674) - correct for your particular helicopter - to
spider & secure with dome headed screw M2.5 x 4 (712).
Dome screw
143B
150 + screws
Bend tabs up
To secure
Fit the spacer washer (143b) to the tunnel. Fit
exhaust/spider next. Fit tab washers (150) & hex screws
(191) in pairs. Just nip screws until all are fitted, then tighten
all ‘a bit at a time’. Bend tabs up to secure.
Stage 2 – Page 1
CENTURY PREDATOR – Stage 2 – Engine/Gearbox
Remove nut and dummy spacer from gearbox shaft, and
fit power turbine – note correct orientation.
Fit nut – counterbore towards turbine. Tighten, preventing
turbine from rotating by inserting small strip of metal
between blades and spider.
Strip of metal
12 cap screws
M2.5 x 5
The interstage can now be fixed to the spider using 12 cap
screws M2.5 x 5 (710). Ensure correct orientation of 8
holes dia. 3 – holes to be top & bottom.
Note relative position of hole for thermocouple.
Note: Hole for
thermocouple
Hole to be at top
M3 x 6 cap
screws
Assemble gearbox assembly to engine, using 8 cap
screws M3 x 6 (713). Ensure ‘Engine top’ matches
‘Gearbox top’.
Cable clip &
Screw M2.5x8
The thermocouple can now be fitted to lower RHS as
shown. It should protrude into the interstage casting by
3mm. Replace the front cover screw with cap screw M2.5
x 8 (711) when fitting clip holding thermocouple. Fit cable
tie (722) to tidy excess cable.
Cable tie
Stage 2 – Page2
CENTURY PREDATOR – Stage 2 – Engine/Gearbox
Wrap interstage/spider with insulation material (678) &
secure with self adhesive aluminium tape (680).
Stage 2 – Page 3
CENTURY PREDATOR – Stage 3 – Frame Assembly
Modify parts from engine kit.
Re solder leads to fuel and gas valves to allow clearance
between canopy & wires. Fit heat shrink tubing over
With heat terminals.
Valve as
supplied
shrink
Wire re soldered
150mm
230 mm
Solder ‘red/green’ lead, supplied with ECU, to fuel pump
after trimming to 230 mm long. Change plug from Tamiya
type to ‘Multiplex’ type (see below for pin layout). Check
‘Tamiya’ type polarity marked on top of pump. Note: Early ECU’s were
connector
fitted with ‘Tamiya’ plugs & sockets, later versions have
‘Multiplex’ items.
Pump
Solder (battery supply) leads 150 mm long between
Multiplex plug and Tamiya plug.
230 mm
Starter
Trim starter and glowplug leads to lenghts as shown,
solder to ‘Multiplex’ socket – see pin layout below.
290mm
Glowplug
Cap &
earth
Glowplug cap
280 mm
Starter +ve (2 pins)
Glowplug earth (2 pins)
Starter -ve
Pump -ve
Battery –ve (2 pins)
Pump & Battery +ve (3 pins)
Regulator
Fit two elbows (703) to fuel valve, one elbow (703) and
one regulator (704) to gas valve. Note direction of flow as
marked on valve.
Gas valve
Fuel valve
Stage 3 – Page 1
CENTURY PREDATOR – Stage 3 – Frame Assembly
Fit valves to left hand side ‘Front frame’ (652), using
servo tape. Fit fuel pump using cable clip (684) & self
tapping screw (687). See drawing (689) for precise
positions.
Important - Jet fuel/paraffin can dissolve the adhesive of
servo tape, keep such fluids away from this area.
Regularly check for damage to tape.
Attach ECU to right hand side ‘Front frame’ (653), using
cable ties (685) as shown.
Cap screw
M3x12
+ nyloc nut
Assemble front mounting strap (677) round engine case
– two bosses to sides & clamping flanges at underside as
shown. Fit clamp screw (M3 x 12) with nyloc nut. Leave
loose to allow strap position to be adjusted.
Add nylon bushes (666) to bosses, flange towards strap
Bush 666
Steel washer
Side frame
Slip side frames over exhaust and over nylon bush. Fit
fibre washer (667) over bush, followed by steel washer
(668) & cap screw M3 x 6 (713) – leave loose.
Fibre washer
Cap screw M3x6
Stage 3 – Page 2
CENTURY PREDATOR – Stage 3 – Frame Assembly
‘X’ Frame 655
Top screws M3x8
Secure ‘X’ frame (655) at top with cap screws M3 x 8
(622). Secure at bottom with M3 x 25 (717) in conjunction
with spacer (658) 18mm long.
Lower screws M3x25
Spacer 658
Fit rear mount (654) to gearbox using cap screws M4 x 12
(716) & washers. Do not tighten – adjustment required. Fit
screws M3 x 8 (622) (with washers-721) through side
frames into mount, centralise in slot, then tighten.
M3x8
M4x12
Mount 654
Apply
Loctite
to thread
Gaps equal
Adjust strap (round front of engine) fore or aft until fibre
washer is in centre of slot as shown. Tighten clamp screw
of strap.
Remove one screw, passing through fibre washer, apply
a small amount of Loctite to threads, and refit. Tighten
screw until fibre washer just nips – the mounting
assembly needs to slide in slot. Repeat with other side.
Strap
View of completed ‘Engine/Gearbox’ unit mounted in its
frame.
Feed pipe
from engine
Photo shows view on underside of engine assembly.
Tunnel lubrication: 4mm pipe from engine feeds a fuel/air
mix to fitting in gearbox. Pipe is covered in a (green)
insulated tube (686)
Note: Early engines did not have the 4mm lubrication
pipe, only an air pipe – fuel to be added later. See picture
& explanation on next page.
Stage 3 – Page 3
CENTURY PREDATOR – Stage 3 – Frame Assembly
690 Elbow
Close up showing M5 Extension (689) & M5 Hose elbow
(690) with insulation pulled back to show fitting.
Note: The plastic washer on part 689 has been removed,
& extension fitted to gearbox using ‘loctite’
689 Extension
Air pipe (red)
Fuel pipe from valve
‘T’ piece
4mm pipe to
gearbox
Restrictor pipe
‘Y’ piece
Lubrication system for early engines
Air pipe from engine (red in photo) is fed into ‘Y’ piece.
The fuel feed pipe from valve is cut, and a ‘T’ piece fitted,
feeding fuel/oil mix to ‘Y’ piece via a restrictor (fitted in
pipe). A short pipe joins the ‘Y’ piece to an adaptor,
increasing the diameter from 3mm to 4mm. From this
adaptor the standard 4mm pipe (& its insulation) joins to
the gearbox as above.
Adaptor
705
A kit is available to supply a lubrication feed from early
engines – Item 705
Stage 3- Page 4
CENTURY PREDATOR – Stage 4 – Final Assembly
Remove standard fan from hub as supplied in kit. Fit
Wren modified fan (675) to hub (upside down) as shown,
using M3 x 6 (713) cap screws and washers (721).
Modified fan is an exchange item.
Fit hub/fan to gearbox output shaft in a similar manner to
‘Predator’ instructions (Op 15 to 17)
Fit clutch shoe as detailed in Op 18
660
661
Fit rear lower frames (Predator part) together with Square
spacer (661), Round spacer (660), using Cap screws
M3 x 50 (718) & original tapped standoffs (26mm).
Replaces original 17mm spacers.
26mm standoff
Fit new spacers (both sides) – 659 (19mm long) & 657
(17mm long) to radio tray using M3 x 8 screws (existing
Predator item) from inside. Screws may be screwed
through tray, or drill out tray & push screws through.
657
659
Stage 4 – Page 1
CENTURY PREDATOR – Stage 4 – Final Assembly
Fit heat shield (make from 100 x 58 x 3mm ply) with
insulation (679) fixed to underside with adhesive
aluminium tape (681). Hold in place with servo tape
pads at each corner.
Heat shield
Fit fuel tank support (656) using (existing) M3 x 8
screws & nyloc nuts, Note orientation of screw heads &
nuts.
REAR
Screw heads
Nyloc nuts
Fit self adhesive foam padding (682) to tank support –
(2off 160mm long). Note semi-circular cut outs to clear
screws (when fitted later)
Cut-outs
682
Starter
shaft
Fit starter shaft (Century part) into clutch – this is only
used to align clutch parts.
2 Centre screws
Loosen 4 adjusting screws on gearbox mount.
2 Side screws
Stage 4 – Page 2
CENTURY PREDATOR – Stage 4 – Final Assembly
Spacers
Lower helicopter chassis over starter shaft, and
continue to lower until spacers on radio tray line up
with holes in front side frames. The slots in the front
side frames should allow the engine/gearbox
assembly to move fore & aft and allow the holes to line
up.
Starter
shaft
Clip on
front LHS
Dia 5
(700)
Apply a small amount ‘Loctite’ on to end of M3 grub
screw (719), and screw into modified canopy mount
(676) up as far as the cross drilled hole. Note:
modified canopy mount is a Wren exchange item.
Canopy
mount
Clip on
front RHS
Top ‘X’ frame
screw
Fit screws (M3 x 8) through frames into spacers & ‘X’
frame at rear positions, as shown on drawing (688).
Fit canopy mount in centre holes, & clips (683 on
RHS) – (700 on LHS) on front holes (using screws M3
x 10).
Also fit screws and spacers (Century items) to top of
‘X’ frame (655). After tightening all the screws, check
that the gearbox output shaft and the clutch assembly
all rotate freely.
Spacer
Adjust clutch engagement (bottom faces flush) as
shown, then tighten the two rear gearbox mount
screws.
Stage 4 – Page 3
CENTURY PREDATOR – Stage 4 – Final Assembly
Screws M3x16
Nuts on top
Screws M3x16
Nuts under
Assemble landing gear struts to skids as shown in
Predator manual – Op.62.
Fit landing gear frame & landing gear (Century items) to
helicopter as shown, noting orientation of screws & nuts.
Note, 3 dia. plain washers should be fitted between
head/nuts and gear struts.
Screws M3x8
Screws M3x8
Nuts under
Boom support strut
Fuel tank
1200cc
Fuel pipe
Cable tied
Foam pad
Attach boom supports struts to rear frames as shown in
Predator manual – Op.90
Fuel tank (691) - 1.2 litre - is attached to tank support
using a cable tie passed through slots in support. A small
pad of tank mounting foam can be fitted between tank and
rear frames each side. Feed pipe (692) to pump should be
secured to landing gear frame using a cable ties.
Use fuel stopper for gasoline/paraffin and a felt clunk (702)
A second
Cable tie
A header tank may be added as shown if preferred.
Pipe from
tank
Fuel system is quite straight forward, fit pipe 693 from
pump to valve. The fuel pipe from the engine (clear) is
fitted into the other side of the valve. The gas pipe from the
engine (green) fits into the regulator (704) fitted into the
gas valve.
Gas pipe from
engine - green
Fuel pipe from
engine - clear
693
Stage 4 – Page 4
CENTURY PREDATOR – Stage 4 – Final Assembly
Left hand side gas tank shown fitted to rear frame using
cable tie. Tanks are supplied in engine kit.
RHS gas tank shown.
Pipe to front
from‘T’ piece
Pipe to filler
from ‘T’ piece
Showing connections to gas tanks – note, coloured pipe
(701) (usually green) is used to interconnect gas system.
Both tanks are connected together via two Festo ‘T’
pieces (697). From one ‘T’ a short pipe (695) is connected
to a non-return filling valve (698). These parts are
supplied with the engine kit.
A pipe (694) is connected to the other ‘T’, which is run
forward and connected to the gas valve mounted on the
left hand front frame
Feed to
engine
Pipe from gas tanks is fed to front of gas valve, whilst
pipe to engine is fed via a gas regulator valve.
Gas pipe
from tanks
Gas regulator
valve
A pump battery is not supplied in the kit, as it has been
found that flyers have their own preference. It can be
mounted above or below the fuel tank – position to suit
model balance.
Stage 4 – Page 5
CENTURY PREDATOR – Stage 2 – Parts identifier
102
141
678
680
712
710
150
143B
713
191
600
711
139
136
674
101
Item No
101
102
136
139
141
143b
150
191
600
674
678
680
710
711
712
713
722
Item
Interstage NGV
Spider
Exhaust wadding
Self adhesive tape
Power turbine
Spacer ring
Tab washer
Hex screw M3x10
Gearbox Assy
Exhaust
Insulation
Self adhesive tape
Cap screw - M2.5x5
Cap screw - M2.5x8
Dome screw – M2.5x4
Cap screw - M3x6
Cable tie 100 long
No Off
1
1
1
1
1
1
3
6
1
1
1
1
12
1
1
8
1
Notes
15 long
310 x 80
100 long
Stage 2 - Parts
CENTURY PREDATOR – Stage 3 – Parts identifier
721
717
677
622
716
720
684
713
687
658
686
685
652
651
655
653
666
667
668
654
Item No
622
651
652
653
654
655
658
666
667
668
677
684
685
686
687
713
716
717
720
721
Item
Cap screw M3 x 8
Front mounting S/A
Front frame LHS
Front frame RHS
Gearbox mount
‘X’ frame
Spacer 18
Nylon bush
Fibre washer 9/32” bore
3 bore x 9 o/d washer
Plug & socket
Pump clip
Cable tie
Heat shield tube
Self tapping screw
Cap screw M3 x 6
Cap screw M3 x 12
Cap screw M3 x 25
Nyloc nut M3
Plain washer dia 3
Cap screw M4x12
Plain washer dia 4
No Off
4
1
1
1
1
1
2
2
2
2
Pair
1
2
1
1
2
1
2
1
2
2
2
Notes
‘Multiplex’ – Not req (Now part of ECU)
160 long
250 long
No 6 x 12.7
Stage 3 - Parts
CENTURY PREDATOR – Stage 4 – Parts identifier
723
722
724
702
659
679
Use ‘gasoline’ stopper
700
681
660
676
719
683
713
675
657
661
715
721
718
656
694
691
692
Item No
Item
No Off
656
657
659
660
661
675
676
679
681
682
683
691
692
694
700
702
713
715
718
719
721
722
723
724
Tank support
Spacer 17 long
Spacer 19 long
Spacer 40 long
Spacer frame
Modified fan
Modified front canopy mt
Insulating material
Aluminium tape
Fuel tank mounting foam
Cable clip dia 8
Fuel tank
‘Tygon’ fuel tube
Gas tube dia 3 (green)
Cable clip dia 5
Felt clunk
Cap screw M3 x 6
Cap screw M3 x 10
Cap screw M3 x 50
Grub screw M3 x 16
Plain washer dia 3
Cable tie 100 long
Cable tie 200 long
Cable tie 465 long
1
4
2
2
2
1
2
1
1
2
1
1
1
1
1
1
4
2
6
2
4
2
2
1
Notes
Exchange item
Exchange items
100 x 58
400 long
‘DuBro 1.2 litre
300 long
400 long
Stage 4 - Parts
682
CENTURY PREDATOR – Stage 1 – Parts identifier
Standard MW 54 gas generator engine kit
Including fuel pump, autostart ECU etc.
And including the parts shown below
704
703
696
699
698
697
701
695
Valves are plastic type
As shown
Item No
695
696
697
698
699
701
703
704
Item
Tube dia 3 (yellow)
Gas tank
‘T’ coupling
Self seal coupling
Straight male coupling
Tube dia 3 (green)
Elbow coupling
Regulator
No Off
1
2
2
1
2
1
3
1
Notes
80mm long
Festo – dia 3
Festo – dia 3 x M5
90mm long
Festo – dia 3 x M5
Dia 3 x M5
Stage 1 - Parts