P Loop Cross-box Combos Half Square Loop

DAS
Cross-box Combos
1/4
1/4
PHASE III
Half
Square
Loop
P Loop
LOOHCS THGILF C/R .S.U TS1
H-52
Cross-box Maneuver Combinations
DAS
PHASE III
The aerobatic box, outside of competition, is the reasonable airspace that a pilot performs his
maneuvers in with good visibility. The performance zone is the smaller airspace within the
aerobatic box where the visibility and presentation is the best, but requiring that the maneuvers
be performed closer together to stay within it. The advanced aerobatic pilot uses all the airspace
within the performance zone by performing maneuvers parallel to both the X and Y axes.
Maneuvering on the (cross-box) Y axis at the advanced level typically consists of performing
two maneuvers to effect a turnaround at either end of the field, while at the same time
repositioning the airplane toward the front or rear of the performance zone. The following
pages contain some of the most complimentary maneuver combinations on the Y axis that also
effect a turnaround.
Aerobatic Box
xis
Xa
Ya
xis
Center Box
X axis
Y axis
Mid-field
Performance Zone
1/4
1/4
Slow roll
Hammerhead
Humpty bump
Side note: The airplane’s flight path is judged
in radio control aerobatics, whereas the attitude
of the airplane is primarily judged in full-scale.
Consequently, without being allowed to “crab”
noticeably into a crosswind, a full-scale airplane
ends up drifting downwind while maneuvering.
Thus, a set of maneuvers on the Y axis are
designed into each competition sequence to
re-position the plane to the upwind side of the
box. This practice will also prove helpful for
H-53
R/C pilots who have not yet acquired the rudder
knowhow to prevent wind drift. Students of
Precision Aerobatics who know how to prevent
wind drift, can use the Y axis to make room for
certain maneuvers and to improve their viewing
perspective. For example: To avoid having to
strain looking up, looping maneuvers are better
viewed some distance out beyond the pilot,
whereas a slow roll is better viewed closer in.
X
Loop
Roll
KPTR: Maneuvering on both the X and Y axes increases the room to maneuver while maintaining good visibility.
Positioning center
box maneuvers
for better viewing
perspectives.
Cross-box Turnaround Combination: Humpty to a Hammerhead
DAS
PHASE III
“one two
one”
KPTR: The first in a series of maneuvers should set up the speed and altitude for the next.
Roll
Half
roll
Left
3 roll
“one
1/4
Roll
Right
3 roll
one”
Hammerhead: Perform the hammerhead with a 3
roll on the downline to exit heading back toward
the center of the aerobatic box. Increase the throttle
to build up sufficient airspeed for the next maneuver
before or during the pullout, not after.
1/4
Roll
Pull-pull-pull humpty bump: Enter the humpty
bump parallel with the runway. 3 roll on the upline in the direction that you want to fly across the
box. Pull over the top, and perform a half roll on
the downline to set up a cross-box pullout to level
flight.
“one two
Each of these maneuvers favor high entry speeds
and finish at high speed. Therefore, this combination works equally well with the humpty bump
before or after the hammerhead, and can be performed to reposition the airplane either to the front
or rear of the aerobatic boxCdepending on which
direction the plane is rolled in the first maneuver.
one two”
The Y axis turnaround combination of a humpty
bump and hammerhead work well together, and
are ideally suited to set up any center (aerobatic
box) maneuver that requires a higher entry speed.
H-54
DAS
Cross-box Combination: Hammerhead to a Humpty
PHASE III
The Y axis turnround combination of
a hammerhead followed by a humpty
bump makes quite an impression.
“one two
one two”
Roll
Left
3 roll
One has the option to perform
a 3 roll on the upline of the
hammerhead: Roll so that
the top of the plane is facing
the front of the box for the
easiest perspective through
the remainder of the upline
and the pivot.
Roll
Right
3 roll
Option
one”
H-55
Half
roll
“one
1/4
one”
Note: Establishing level flight between maneuvers provides a moment
of respite to begin anticipating what
is next and to ensure that the wings
are levelCalong with being an important competition requirement and a
stamp of proficiency.
Roll
Pull-pull-pull humpty bump: ¼ roll
on the upline in the direction that you
intend to pull over the top. In this
example, that will be to your left
(toward the center of the aerobatic
box). Pull over the top, and perform
a half roll on the downline to exit
heading back toward the center of the
box.
1/4
“one two
Hammerhead: Enter the hammerhead parallel with the runway.
Perform a 3 roll on the downline to
set up a cross-box pullout to level
flight.
1/4
1/4
KPTR: A proficient pilot establishes a definite level
end to the first maneuver before entering the next.
Cross-box Combination: Pull Humpty to a Push Humpty
Back-to-back humpty bumps
on the Y axis work well together, and are made more
interesting by pulling over
the top of the first humpty,
and pushing over the top of
the second.
PHASE III
1/4
Roll
.
KPTR: Anticipating which way to roll and push or pull
stems from routine wings level entries and perfect verticals.
“one
one two”
Roll
Left
3 roll
Half
roll
one”
“one
Roll
.
“one two
Right
3 roll
Note: If considerable rudder
is applied trying to correct a
deviation from vertical at the
point of initiating the pull
or push over the top, that
rudder will likely have to
be maintained and will take
precedent over the usual
P-factor rudder corrections.
I.e., “pull-right---push-left”
at slower speeds only works
on a consistent basis when
the pull or push starts with
the wings level after a truly
vertical upline.
one two”
1/4
Pull-pull-pull humpty bump:
3 roll on the upline in the
direction that you want to
fly across the box. Pull over
the top with right rudder.
Perform a half roll on the
downline to set up a crossbox pullout to level flight.
Pull-push-pull humpty: 3roll the airplane into position
to push over the top toward
the center of the box. Push
over the top with left rudder,
and hold the downline for a
few counts before pulling out.
DAS
H-56
Half Square Loop Setup to a Spin
DAS
PHASE III
To spin
The following page contains a Y axis turnaround combination requiring
a higher altitude setup to a spin. Every aerobatic pilot should be familiar
with using the Immelmann turnaround to gain altitude. The turnaround that
advanced pilots use to more precisely control just how much altitude is
gained is the half square loop.
Note: While a spin can be set up in any direction, it is much easier to keep
within the performance zone when set up into the wind. Therefore, the half
square loop turnaround should be performed downwind of center box.
“one two three four”
Half square loop
You also have the option to
perform a half roll on the
upline of a half square loop,
and then push to upright
flight.
Option
1. Approach the entry at high speed, full power, with the wings perfectly
level. Pulling to the upline should be smooth, but completed quickly,
in order to minimize the chance of a deviation occurring during the pull.
2. Maintain full power to improve controllability and tracking once you
get to the top. And unless there is a strong contrary crosswind, look for
and expect to need increasing amounts of right rudder at some point
along the upline to counter the increasing effects of slipstream.
3. Approaching the targeted altitude, assuming the upline is truly vertical,
smoothly pull elevator with increased right rudder to cap off at the top
inverted. One can then maintain inverted flight to set up an inverted
spin, or roll upright to set up an upright spin.
Side note: With all the twisting and turning going on at this point, should
there be any question about the direction to apply the rudder when a deviation from vertical is first detected, knowledge of the increasing effects of
slipstream along an upline should provide assurance that right rudder will
correct it. However, keep the rudder input initially small and watch the
plane closely, just in case it has to be switched for whatever reason.
(FYI: The battle to correct the upline after it was entered without level
wings will be greater than battling a 20 mph direct crosswind!)
H-57
KPTR: Counting on the upline will help you consistently match the right altitude to the number of spin revolutions that will follow.
Cross-box Combination: Upright Spin to a Hammerhead
DAS
A popular Y axis turnaround combination is the
13-turn upright spin followed by a hammerhead.
Here, a 23-turn spin is performed to afford the
pilot a little more time to anticipate the spin’s
cross-box recovery.
Left upright spin
“one two
A 23-turn spin set up parallel with the runway
will exit cross-box in the same direction the
spin was initiated (into the wind typically). You
should avoid initiating a spin with the wind, since
the wind will displace the entry and cause it to
appear barrel-rolled or prematurely forced! If there
is no crosswind component to the wind, one’s only
concern is to initiate the spin in the direction that
you want to be heading after the spin.
PHASE III
“one”
1/4
1/4
Cr
os
s-b
ox
“two”
one”
Immediately after the spin stops, push to a perfect
vertical downline, square the wings if necessary,
and start applying power to build up airspeed for
the hammerhead. Due to the lower airspeed
exiting a spin, keep the next maneuver simple (no
rolls on the upline). 3 roll on the downline after
the pivot to exit heading back toward center box.
Right
3 roll
Roll
As you sense the stall about to break, sneak in a
little rudder in the direction that you intend to spin
to ensure the spin breaks that way. Once you
input the spin, keep track of the revolutions from
the beginning, and quickly neutralize the controls
on “two,” in order to stop spinning at 23.
Side comment: It is because the vast
majority of R/C flyers recover from
their spins in whatever direction the
airplane happens to be heading that
few things are as impressive as when
a pilot enters a spin in one direction,
recovers in another, and then validates
that it was no accident by performing
another aerobatic maneuver!
KPTR: As a rule, given the choice to spin left or right, choose the direction that is more into the wind.
(neutral)
H-58
Cross-box bridge spin entry: Enter the bridge
parallel with the runway. Set the upline, and
3 roll the airplane into position to (push) cap off
at the top upright (into the wind typically).
Maintain an even count along the upline to
achieve sufficient altitude to perform the spin.
This practice then reinforces correctly matching
the altitude gained to the general number of spin
revolutions that you intend to do, e.g., a longer
count sets up a higher altitude spin entry and
more revolutions.
Stall
“one”
“two”
Neutral
“three”
Upright spin: Once you have initiated the spin,
start counting the revolutions when the top of
the plane faces the direction that you intend to
recover, and neutralize the controls just before
achieving the number that you want to stop on.
Note that while a bridge or half square loop setup
to a spin may make it possible to do several revolutions, it is more dynamic to perform fewer
revolutions in order to demonstrate a perfect
vertical downline afterCversus spinning until
altitude forces a rushed pullout.
H-59
Side note: Consistently entering maneuvers with the wings
level and attention to using the
same inputs usually leads to
quickly noticing any additional
corrections that haven’t been
covered here, but turn out to be
needed in practice. One such
example can occur flying a
high power airplane turning a
very large propeller: A more
aggressive pull to the vertical
can produce so much P-factor
effect that the plane turns a
little to the left, despite the
higher airspeed. Obviously, a
little right rudder during the
pull will correct this until the
upline is set, at which point no
more rudder should be required
until slipstream begins to take
over as the airplane slows on
the upline.
one two three”
An example of efficiency and proficiency using
one maneuver to set up the next is performing a
cross-box bridge to achieve the altitude for a spin,
while also decelerating close the stall speed so
that a spin can be entered on the Y axis without
needing a lengthy setup.
Right
3 roll
KPTR: A bridge is a great way to quickly gain altitude to set up a spin at the upwind end of the field.
Roll
PHASE III
Cross-box Combination: Bridge to an Upright Spin
“one two
DAS
P Loop Turnarounds
DAS
An advanced turnaround maneuver that is seldom seen outside of aerobatic competition, but that
offers more versatility than just about any other maneuver, and is also a lot of fun to fly, is the P loop.
Roll
one”
NOTICE: All that can be said about the proper
uses of rudder to prevent crosswind drift during
loops (and for that matter, keeping loops round)
has been said in Precision Aerobatics, and
therefore will not be repeated again here. Let it
just be said, for the sake of those who have
skipped that phase of learning, look for the leftturning tendencies of slipstream and P-factor
to require right rudder corrections during the
slower phases of maneuvers. Yet, at a certain
strength, crosswinds become the dominant force
requiring rudder correction, particularly over the
slower tops of loops. Knowing what to look for
and experience will tell.
Half
roll
Slipstream
RUDDER
or
Crosswind
one two”
“one two
Half
roll
Use right rudder over the
slower top of the loop to
correct P-factor and slipstream. Unless, rudder
into a strong crosswind
is required.
The P loop turnaround
with a half roll on the
upline before a : loop
sets up a higher entry
into the next maneuver.
Roll
or
Crosswind
P LOOP
The P loop turnaround
with a half roll on the
downline after a : loop
sets up a lower entry into
the next maneuver.
“one
P loop
PHASE III
Use right rudder to correct
slipstream as the airplane
slows along the upline, and
increase the right rudder to
correct P-factor and slipstream looping over the top.
Unless, rudder into a strong
crosswind is required.
Reverse P loop
P LOOP
KPTR: The ease of the next maneuver will directly reflect whether the P loop was kept vertical.
H-60
Cross-box Turnaround Combination:
P Loop to a Humpty Bump or Hammerhead
DAS
Reduce
power
PHASE III
Performing a P loop followed by
a humpty bump or hammerhead
on the Y axis combines an awesome display of aerobatic skill
and flying as a stylistic art form!
“one two
“one two
one two”
P loop:
1/4
1/4
Left
3 roll
Left
3 roll
one”
H-61
one”
Note: Anytime a refinement like
rudder is needed, remember that
if you do not input enough, you
will still improve the maneuver.
On the other hand, continuing to
increase the rudder until its effect
is obvious, can turn an acceptable
maneuver into a sloppy mess.
If in doubt, input less, rather than
more.
Half
roll
Roll
ox
Roll
s-b
Roll
os
“one
Cr
Approach the entry
from a medium altitude, parallel with
the runway, at high
speed, wings level.
Smoothly (not gradually)
input and hold a fixed elevator amount to initiate a
constant radius loop.
Relax the elevator slightly
to float over the top of the
loop and keep it round.
Reduce power and set
the downline.
3 roll on the downline to
set up a cross-box pullout
to level flight....
KPTR: (With the exception of correcting vertical snap rolls) it is better to err on the side of not enough rudder than to over-control!