On Jun 5, 9:40*am, Dudley Henriques wrote:
More_Flaps wrote:
My aerobatic traing is going very well, I'm having all the fun I
thought it should provide. So far I haven't messed up a manouver but
I'm nagged by the thought: How can I tell if my loops are perfect
circles? At present I go to full power at the vertical phase and over
the top but then throttle back a lot as I go vertical again .My wings
are level when inverted. I'm pulling 3.5 G as I pull up and level out
again. I hit my wake every time but I wonder how much I should
throttle back on the descent phase. Should I just try to keep rpm
constant? Any ifeas BtB or Dudley or other aerobatic pilot?

Cheers

Constant speed prop or fixed pitch? Makes a difference.

Basically, what you're doing in a loop is controlling energy by varying
g and airspeed. The main error pilots make that causes egg shaped loops
is in not easing off the g through the high apex. If you don't ease off
the g through the top you pull the nose down and spoil the circumference
of the maneuver.
As for power control, if you are using a constant speed prop, leave it
alone and use MP (if at all) to control airspeed. In most trainers like
the Decathlon for example, you can just set the airplane up power and
prop wise and fly the loop starting with the suggested entry airspeed
and vary the g to control the shape of the maneuver without touching the
engine controls at all. With a fixed pitch prop, you can increase power
on the way up the vertical line (watch the redline) and decrease it on
the backside (watch the redline). Be especially watchful for overspeed
with the fixed pitch prop.
Generally your g profiule sounds about right 3.5 to 4.0 are good
profiles for the average trainer using about 140 for your entry.

Hitting the wake is a good sign. Sounds like you're doing ok to me.


Thanks D, my entry is 140 as you suggest and i'm exiting close to that
speed. Its a fixed pitch plane and I am trottling well back on the
dive (2000 rpm) and my G at the top is dropping to about 0.5, I'm
easing the stick only slightly as I go over. Any other ideas that I
can use to evaluate my circularity (or lack thereof?).

Cheers