>And judges could let us know
>>the major errors they see.
>
>I have a few pet peaves.
>
>There is so much emphasis on squares and corners, what about
>the rounds? Rounds are round. When a stunt plane flies a
>true round the tail never stops turning at a constant angle
>of attack. If the tail stops turning, that's called a
>"flat". Rounds are not flat anywhere.
>
>Mostly what I see are the follwing.
>1. Not steeep enough angle of entrance. The airplane
>should begin turning quickly and constantly. Most entries
>are too slow, and that is why the first loop is walked to
>the left, and the second two are slightly right.
>2. Flats on the tops. Super common. Not dinged nearly
>enough IMHO.
>3. Flats on the tops lead to late hook-flips on the
>bottoms.
>4. "looking for the top, looking for the bottom, looking
>for the top, looking for the bottom, etc...."
>5. Too big, try smaller. It is actually easier.
>6. Be aggressive. Pull the airplane round.
>
>For excellent rounds watch Ted, David, and Doug Moon.
'zilla,
Good stuff. Here's a bit of a kicker, however. You are exactly correct that the "tail should never stop turning". No exactly the way I would have described but exactly true nonetheless. What can't be extrapolated from that statement, however, is the expectation that the motion will be constant for a "round" loop. This is pretty esoteric stuff, but important. From the judge's or pilot's point of view you can't let yourself be satisfied with a constant rate of tail motion. Here's why.
The rules state that we are looking for a flight path that describes a true circle...and constant radius. This seems to imply what you suggest in terms of a constant rate of change of the tail relative to the flight path. Actually, this is never true and in some cases might even be significantly in error.
I think we can accept that the circular path we are looking for will be traced by the Center of Gravity of the ship. If we could mount a laser flashing from the CG directly across the circle we could photograph the pulses and determine how precisely the airplane as an entity traced a circular path.
What the path of the tail will be telling us throughout this circular CG path is what angle of attack the aircraft required in order to devleop the lift necessary to achieve this path. On a very light, high speed ship this tail rate of change angle will vary only a tiny amount and might even appear to the judge to be a constant.
If, however, the ship is heavy and flown slowly the angle of attack required to maintain this constant CG radius will alter significantly as the G forces and the airspeed constantly vary throughout the loop.
This will result in a comparatively slow tail motion relative to the CG path going up and a much more significant relative motion coming downhill after the ship has slowed in the climb and then needs a progressively higher angle of attack to maintain the radius as the airspeed gradually increases...consequently reducing the angle of attack.
In other words, the motion of the tail relative to the CG will be constantly changing based on the constantly changing airspeed and the consequent change in angle of attack necessary to continue to produce the lift coefficient required to maintain the CG's circular flight path at constantly changing airspeeds.
Thus, the judge has to be very cautious not to interpret the increasing rate of tail motion relative to the aircraft path as an egg shaped increase in the rate of flight path change.
This is just a very long winded way of stating that evaluating the flight path of round maneuvers isn't as easy as one would think. Also, that the perception of the flight path (similar to earlier threads discussing the "illusion" of corners) won't always be completely accurate.
Judging ain't easy.
