Wasn't the demonstration of the ignorance of physics by some of the
posters fun?

I don't think a GA airplane has the control authority to do one of
these 'rolls' but maybe.

But you could start the thing with a coordinated turn and forward
yoke, and maybe get to 45 degrees bank and a lot of downward pitch
maintaining 1 G before getting back to straight and level,

His first model with 10 seconds total time means 320 fps downward
velocity, about 200 kts down at its end. He pointed out the total
altitude loss from start to finish was 1600 feet or so, but then
comes pull out from lots of vertical speed. Moral: start high and
pull out smoothly or turn the airplane into a kit.






On Jun 14, 8:47 pm, Jim Logajan wrote:
wrote:
Jim, you don't have to do the physics for a 1 g roll. click on

stanford.edu/~sigman/one_g_roll.html for a really neat analysis.

Page down toward the end of sigman's article to see the actual flight
paths that it takes. It's a neat read.

Oh, for the nonbelievers in Newton and vector analysis and such (Mx
whatever comes to mind) don't bother.
OPPS, It'swww.stanford.edu/~siegman/one_g_roll.html

Fascinating - thanks for finding that! Amusing to note that a physicist of
that caliber was motivated to explore the situation due to an older thread
on the same subject on the same Usenet newsgroup! I considered setting up
the same situation using Mathcad 2000 (it can generate animations, so I
think I could have set up appropriate parametric equations and created a 3D
movie). But I just don't have the time at the moment to do that.

At least I feel better that my physical intuition didn't fail me.

The nit pickers may (reasonably) argue that the trajectories don't yield
the "barrel roll" spiral they might insist on, but such is life. I should
have titled this thread "Myth: 1 G rolls are impossible," and dispensed
with the word "barrel."