[NSRCA-discussion] Snap Entry

[John Gayer]

Actually a snap can occur without any aileron input...but I challenge 
anyone to show a pattern ship doing a snap roll on a 45 degree downline 
without ailerons.

The approach snap can occur with only the use of elevator and it  
involves one wing panel stalling before the other. Try an approach with 
crossed controls(aileron/rudder with some power. pull the nose up 
gradually and see which wing drops. It will be the wing with the aileron 
trailing edge down. This is contrary to what we see in a pattern snap 
roll which always snaps in the direction of the aileron deflection thus 
indicating the lack of any stalled condition

John

seefo at san.rr.com wrote:

>Just to stir the pot a little further..
>
>I'm not sure a contemporary pattern plane can generate enough pitch rate to reach critical angle of attack and properly perform a snap roll. I think it's far more likely that we're seeing nothing but a heavily yawed aileron roll, with the pitch break only being shown to judges to convince them there is actually a stall happening, when in fact there is not. 
>
>If a snap cannot occur using ONLY elevator and rudder, then the wing is not stalling. Aileron inputs into a snap actually inhibit flow separation, as the inboard wing angle of attack is drastically reduced, and the outboard wing AoA is drastically increased. 
>
>But since there is no way to actually determine what is happening aerodynamically on an F3A airplane, the best a pilot can do is fly the airplane to what the judges expect to see based upon the rules. It really doesn't matter what the control inputs are if the airplane LOOKS like it's doing the right maneuver.
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