Great Planes Cherokee Kit - GPMA0180 - Manual (Page 28)

FLYING WITH FLAPS
Flaps can add a whole new dimension to the flying character-
istics of your Cherokee, so we hope you'll use them. With flaps,
your model will take off and climb quicker plus land at a higher de-
scent rate while touching down at a slower speed Why? Because
as the flaps are lowered, they increase the lift of the wing Along
with the increased lift there is increased drag The more the flaps
are lowered, the more lift and drag is increased
Before using flaps, become familiar with the way your Chero-
kee flies Put in a minimum of 10-20 flights to familiarize control
response, power response, stall speed, etc Also, make sure the
Cherokee 's perfectly trimmed out.
Throw adiustment
Flaps should be on a separate channel, preferably a propor-
tional one that will allow you to add varying degrees of flaps Total
throw should be no more than 3 / 4 " as measured from the trailing
edge of the wing to the trailing edge of the full deflected flap.
T a k e o f f s
While taxiing, add 1/2 flaps (3/8 inch) Don't use full flaps until
you've gained experience with 1/2 flaps When you're headed into
the wind add full power You'll notice the Cherokee will rise off the
ground in a shorter distance than normal As the plane gains speed,
the added lift of the flaps will make your Cherokee nose up This
can be corrected by
1) raising flaps
2) decreasing power
3) adding down elevator (or trim)
With full size planes, flaps are pulled up after the plane has left
ground effect as the plane is gaining speed and altitude Power is
not reduced until the aircraft is at cruise altitude The same could
follow for your model
Takeoff Procedure (Novice)
1)Add 1/2 flaps
2) Check engine for reliable operation
3) Check radio functions
4) Point model into wind
5) Add full power
6) Pull only a small amount of elevator until model breaks
ground
7) Climb out, being careful to keep the airspeed up
8) At safe altitude bring up flaps
9) Reduce throttle to cruise
Takeoff Procedure (Advanced)
1)Add full flaps
2) Double check engine operation
3) Check radio
4) Add a couple notches down trim
5) Point model into wind
6) Add full power
7) Add small amount of up elevator until model rotates,
then be prepared to add down elevator stick to maintain
airspeed during steep climb
8) Climb to safe altitude - watch airspeed
9) Bring up flaps slowly
10) Return elevator control to neutral
11) Reduce power to cruise
Adding f l a p s at cruise speed, straight & level
Flaps are installed in aircraft to help them take off and land in
shorter distances If you drop the flaps at full speed, your model is
going to pitch up, maybe severely This can be corrected by adding
down elevator pressure, but this imparts extra load on the airframe
(especially the flaps)
Landing
Flaps are used on landing approach to steepen the descent
rate They are very effective, and with a little practice, you can make
landings at dramatically steepened rates
Technique is important As flaps are deployed, the increased
lift should be compensated for by down elevator pressure This
down elevator, combined with the added lift/drag of the flaps, in-
creases the descent rate without increasing airspeed' Of course,
adding too much down elevator will increase airspeed, but practice
will show you how much to add
There are many ways of using flaps — we will explain two pos-
sible methods.
Novice
1) Enter rectangular approach, but start at 50% higher alti-
tude than normal
2) Downwind leg — reduce throttle to 1/2.
3) Next, add 1/2 flaps
4) Add slight down elevator trim to compensate for flaps
5) On final approach, reduce power as necessary to estab-
lish descent rate to runway If too short, add power (don't
pull back on the elevator')
6) Flare as usual on runway (you'll note landing speed is
reduced somewhat.
Expert
1) Enter rectangular approach 50-100% higher than normal.
2) Reduce throttle as usual during downwind leg
3) On final, reduce throttle to idle You should be a lot
higher than normal
4) Add full flaps, and as you do, add down elevator to main-
tain constant airspeed and a steep descent
5) If you're short, reduce down elevator and/or add power If
you're long, add power, retract flap and go around
6) As you approach runway surface, reduce down elevator
and when ready to flare, a little up elevator will slow
plane down to landing speed You'll find the stall speed
is reduced quite a bit for nice nose high, slow
touchdowns.
Like anything else, flaps take practice If you would like further
explanations of the use of flaps, consider reading rull scale flight
manuals Generally, the techniques are the same Of course,
models are more of a challenge because we are not in the cockpit
to read airspeed indicator, tachometers, nor line up a spot on the
cowl with the runway threshold' But in time, you'll get the feel of it.
That's the fun of flaps'
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