One G rolls: a physicist's view

In article ,
"Kyle Boatright" wrote:

Good analysis. One thing you might try is running the model again at 6 or 8
seconds to complete the roll? This would be would be representative for many
GA aircraft, which have roll rates of ~45 degrees/second? I imagine it
would make a huge difference in the vertical velocity at the end of the
roll.

Thanks for reaction (I'm always a bit worried when I'm calculating
something outside my personal experience). Results for a 6 sec roll are
at:

http://www.stanford.edu/~siegman/one_g_roll_6_sec.html

As expected, a lot less altitude loss and downward velocity buildup.


Also, most of us who do rolls in aircraft with non-inverted systems begin
the roll with a pull-up to a 20 degree (or so) climb. In my case (RV-6), I
pull 1.5 G's to the 20 degree upline, roll at more or less 1 G, and pull out
at 1.5 G's when the roll is complete without any net altitude loss...

KB

I'll run this when I get a few minutes to do it. Or, if anyone has
access to Mathematica (a truly great software program, but expensive
unless you can get an academic discount), I'll be glad to send the
original notebook.

I really liked your analysis, but offer the following.

If we fly coordinated -- that is, use the rudder to keep the ball
centered our degrees of freedom are ailerons to control rate of bank,
elevators to control pitch (pulling the nose up, or pushing it down)
and throttle/flaps to control acceleration/deceleration.

Someone pointed out if the airplane was allowed to accelerate downward
at 1 G, the 1 G roll could be accomplished by simply pulling back on
the yoke hard enough to cause 1 G acceleration in the pitch direction
while a coordinated roll was flown. This is different than a constant
velocity model, but also works.

Thanks for crunching the numbers!