Thanks for that. I was thinking mostly about flat / falling leaf spins, but
there are some definate "food for thought" in this regard in what you wrote.


"nafod40" wrote in message
...
Cockpit Colin wrote:
One way to think of it (not too scientific) is that adding power just
adds more "juice" to the spin. The power vector rotates around, just
making the plane do whatever it's doing with that much more vigor.


I understand what you're trying to say, but I just can't get a handle on
the
physics of it ...

OK, stream of consciousness here. Ignore any violations of the law(s of
physics).

A plane in a spin is yawing and rolling simultaneously. It is also at a
stalled angle of attack. What happens is that, as the AOA of a wing
increases, its drag always increases, but at a certain point its lift
decreases (near and past stall speed). So in a spin (to the left) the
left wing has a higher angle of attack, due to adding the downward
motion of the plane and the relative motion of the spin (steal kid's F-4
model, experiment), than the right. It has higher drag and less lift,
and so the plane rolls left and yaws left. You get spin.

To break the spin ususally you must break the yaw, which puts both wings
back into an equal amount of AOA condition. To break the yaw you need to
create a moment. The moment is created typically with rudder, and
sometimes helped by tricks with ailerons. The thrust would not help with
creating a moment.

So what would it do with more thrust? Well, if the nose was pointing
down, it'd make the plane fly "heavier" due to a downward component to
the thrust. That'd give you more spin.

As for the thought of having the thrust fly you away, if you watch how
fast planes spin, versus how fast they accelerate on takeoff with full
blower, you'd see that before it'd have chance to accelerate in one
direction it'd be pointing another, so to speak. Mathematically
speaking, say you wanted the plane to fly away to the east. Integrate
the component of thrust that points east over a half-rotation of spin
(less than a second?) and divide that by the mass of the plane to get a
delta velocity eastward over the half-rotation. Or something like that.
Small number which is immediately cancelled by other half-rotation. A
plane in a spin carves a slightly spiral trajectory. It'd make the
spiral a wee bit bigger. Not enough to matter.

That's my story (based on 200+ inverted spins in a Buckeye...thought
processes cloudy now), and I'm sticking to it.