 | There is more to this maneuver than meets the eye, so let's take a
close look at this it, one section at a time.
| Model not level at start and
finish. As with every maneuver, the Stall Turn starts and ends
with STRAIGHT AND LEVEL FLIGHT! You're probably getting tired of
hearing me say those words, but get used to it. They are probably the
most important words you'll read on these pages. If your entry is not
straight and level, the rest of the maneuver will fall apart rapidly.
It's also a downgrade. Get it right!
NOTE:The one-quarter loop
begins on the center line! This is vitally important. It is easy
for the judges to see where center is, and just as easy to provide
downgrades when you miss starting the 1/4 loop there.
|
| Track does not become exactly
vertical. First, let's review the definition of TRACK:
the trajectory or flight path of the center of gravity of
the aircraft over the ground. Notice that it doesn't say anything
about the attitude of the aircraft. They will be identical in no-wind
conditions, but otherwise will be different to compensate for wind
drift. Many new pattern pilots try to make the attitude of the
plane vertical. If there is any wind, the plane will drift back
in the downwind direction. This will bring immediate downgrades from the
zebras -- oops, I mean judges. Sorry, too much football today.
Note that we are flying in three dimensions, so there is also an
excellent possibility that the plane will try to drift left or right as
well as backward. I don't know about your field, but the wind is seldom
down the runway at mine. Left or right drift is corrected with Rudder.
You know, the other control over on the left stick with the throttle.
Use as much rudder as needed in the opposite direction from the drift to
stop the drift. In other words, if the plane is drifting to the left
(looking at the top of the plane), apply right rudder. One of my pattern
cronies here on the Prairie was having trouble with his Stall Turns last
summer and asked me for help. Every time he'd start to drift left, I'd
say "Right Rudder!" He'd just keep drifting left, so I repeat
my "Right Rudder" suggestion. After several attempts he
finally said in exasperation, "I've got right rudder in it!" I
told him "Put in some more!" Use whatever type and amount of
control input it takes to correct the problem as quickly as you can,
because it will only get worse if you don't.
Another possible culprit that causes right or left drift is our old
friend and nemesis, wings level. If your wings aren't perfectly
level when you start the 1/4 loop, the plane's heading will be off in
the direction of the low wing. You've violated the "track being
vertical" rule even before your start the maneuver. Remember, the track
needs to be vertical, not the attitude.
| NOTE: |
A word here about the loop from your friendly webmeister.
Use a nice large radius on your loop. This will allow you and
the judges to get a good look at the TOP of your plane during
the vertical segment. This is very important in seeing any wind
drift as soon as possible -- so you can correct it at soon as
possible. It also presents the maneuver to the judge in a much
clearer manner, and allows better timing of the stall turn. |
|
|
| Model not vertical at start and finish of
the ... stall turn. This may seem a little strange, especially since
the maneuver must be wind corrected. However, just before the stall turn,
the model must be put into a perfectly vertical attitude relative to
the ground! I know it sounds difficult, and it does require some timing and
practice, but it can be done. The airplane must remain vertical throughout
the 180 stall turn, then wind correction is reapplied as necessary.
|
| Return path not parallel to entry path.
The track of the airplane on the downward leg following the stall
must be parallel with the upward track prior to the stall. Wind correct as
required. If the wind is down the runway, down elevator will be required.
|
| Exit not at same altitude as entry. Sounds
elementary, but it is often overlooked. Following the 1/4 loop at the end of
the downward line, the exit altitude must be the same as the entry altitude.
|
| Pivot radius greater than 1/2 wingspan.
When executed perfectly, the airplane should pivot about it's own Center of
Gravity. The worst case allowed with downgrade is for the plane to pivot
around its wingtip (radius of pivot = 1/2 wingspan). This requires some
technique. There are two basic problems usually associated with stall turns.
The first is the flop, caused by waiting too long before applying rudder,
allowing too much airspeed to bleed off. Problem two is flying through the
stall, not pivoting. This is caused by applying rudder too soon!
Here are two things that will help you with your stall turns.
- Add a little throttle during the Stall Turn. There are several ways of
doing this. One is to use the stick to give a couple of clicks of
throttle just before the stall turn. Another is to set the throttle trim
to a high idle during the maneuver. This is your webmeister's favorite,
and it's particularly simple if you have a computer radio. Simply mix
Throttle into Throttle and control it with a switch -- just flip the
switch to high idle during the turnaround preceding the stall turn and
flip it back to low idle during the next turnaround. That let's you
maintain the low idle setting needed for takeoff and landing, but still
give the extra boost needed for the stall turn. Both of these methods
will cause airflow over the rudder during the stall, increasing it's
authority and giving a much cleaner stall.
- Practice, Practice, Practice!!! There is no other way to get the
timing correct than to practice it until you can do it right every time.
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