Snap roll vs. Va

Hi Greg,

You're right, dynamic stall occurs when a wing or other lifting
surface is subjected to time-dependent pitching (or other type of
time-dependent) motion, resulting in a greater effective angle of
attack than the normal, static stall angle.

But the "dynamic stall" phenomenon does not really apply to light
airplanes. It is is an unsteady stall phenomenon which can be
experienced by the retreating blade of a helicopter in forward flight
and by highly maneuverable fighter aircraft.

"Dynamic stall" means something to skydivers as well, I think when a
skydiver pendulums under the canopy too close to the ground...

Rich
http://www.richstowell.com


Greg Esres wrote in message . ..
which translates into a 2.5-g pull to stall/spin the airplane at
that speed. The MAXIMUM snap roll speed should probably be no greater
than about 1.7 to 1.8 x Vso...

Rich:

Thanks for your reply.

The genesis for my question is that there are a number of aerodynamic
sources which discuss the concept of a "dynamic stall", where when the
a/c is rapidly rotated to a high AOA, it can generate a much higher
lift coefficient than in steady state conditions.

My thought is that a snap roll should duplicate those conditions.
However, the g-forces you're reporting don't seem to match that
theory. Bill Kershner said that he does snap rolls at 80 knots, and
has never seen more than 3 g's in his Aerobat.