Doug,
Your observations and suggestions sound right on the money. The gyro is
happening exactly the way you describe it and it does autogyrate on the
downline until I get enough airspeed for the controls to become effective
again.

I'll check to make sure I'm vertical on both wingtips, hold in a little
forward stick pressure during the kick, and try easing the power out during
the kick and see what happens. Gotta be better than pointing my nose all
over 50 acres of ground.

Cheers!
Shawn
"DSowder" <dsowder@aol.com> wrote in message
news:20020407233648.13751.00002800@mb-da.aol.com...
>Hammerheads should be dead simple to do but I'm consistently having a
>problem I can't figure out so I put it to the collective wisdom here to see
>if any of you might have encountered the same.
>
>Aircraft is Pitts S-1D. Entry speed is 160 mph. Vertical upline is fine.
>No aileron needed to counteract torque, holds nice and steady. Kickover
>rate at the top is OK, too. However, when I kickover, the nose starts to
>gyrate so that I come out on the vertical downline having tucked under and
>now PAST the vertical. It seemed like a gyroscopic problem so I thought
I'd
>cut the power just at the start of the kick. (bad move.

In my humble opinion, the Pitts S-1 is not particularly easy to hammer
consistently. With respect to its aileron and tail moments, its propeller is
huge, and you're right that there's a gyroscope at work. First of all, if
you
don't have some aileron deflection on the way up, you might be kicking too
early, or you might be holding some right rudder on the vertical. Check both
wingtips to be sure you're vertical in the lateral sense.
When you yaw to the left, as in kicking for the hammer (and I assume you use
left rudder...), the prop's gyroscopic precession tries to pitch the nose
toward the pilot. This force depends on RPM, not on power setting. Once this
pitch gets started, it's very hard to stop, and the result is "on your back"
after the pivot. I've seen this result in unintended autorotation, through
my
own windshield. Anyway, you might try some forward stick simultaneously with
the kick, even if it doesn't seem like the pitch has started yet.Once you've
pivoted about halfway, pulling the power briefly will kill the torque and
help
prevent "torquing", and at this point you'll need to neutralize the elevator
or
even hold a touch of back stick.

In the S-1, timing is really critical, and I always found myself "flying"
all
the way through a hammer. My S-2B is much less critical, and it's hard to do
a
bad hammer.

Just my observations.
Doug Sowder

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