In article , "bumper"
wrote:

It went into an unstable phugoid oscillation with each dive being steeper
than the previous. I chickened out and stopped the "test" early on after my
ears got pinned back - - and I was in a closed cockpit (g).

I did not have spoilers or gear out.

That's the problem. The more drag you can put out the more stable it is.

Here's why.

First of all, more drag limits speed buildup when the nose is down,
giving time for the extra lift from increased speed to raise the nose
before the speed is such that you're going to go way nose up.

Second, you are never going to have a roll rate of precisely zero. It's
only manual corrections that keep the wings level (or at constant bank),
wich you can't do when you can't see. Given enough time, even a tiny
roll rate will tip you over. BUT, when you're gliding (losing altitude
comparred to the air) a portion of the roll rate goes directly into
changing your heading. The steeper your glide angle the greater that
coupling is. If you're 90 degrees nose down (which gliders with really
good airbrakes can do at a safe speed) then *all* the roll rate goes
into changing your heading, and none of it into tipping you over. If
you're 45 degrees nose down (which all cerrtified gliders can do) then
70% of the roll rate goes into changing your heading. Even at 1:7
(which certified gliders must be able to acheive at approach speed), 15%
of the roll rate goes straight into changing your heading. At 40:1 only
2.5% does.

Anyway. The point is that even if you have quite a large roll rate, if
your nose is well down, with the speed stabilised with drag, then the
roll rate just makes you turn faster instead of tipping you over, and
your bank angle will stabilize at almost certainly no more than 45 - 60
degrees, and quite probably only 30 degrees.


Every aircraft is different. But drag is the key to the whole thing.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------