On Wed, 21 Sep 2011 08:58:58 -0500, Sunworshipper SW@GWNTUNDRA
wrote:

On Wed, 21 Sep 2011 05:40:36 -0700 (PDT), Dave__67
wrote:

On Sep 20, 10:48*pm, Richard wrote:
On 9/20/2011 8:11 PM, Artemus wrote:



Subject: Two Questions
We have all seen the pictures of this tragedy at Reno, but I have two questions.

1. *Would losing the trim tab on one side of the elevator really cause this type of
loss of control?

Yes.

As an airplane travels faster the wing makes more lift.
To keep from climbing the nose is pushed down.

While the trim tab looks tiny compared to the rest of the aircraft, it
is really all that is holding the nose down.

Trailing edge of the tab would be up which forces the trailing edge of
the elevator down, thus pushing the the nose down.

Sudden loss of that tab means a sudden nose up - and at those speeds
if would be exceptionally violent pitch up.

2. *Why is the tail wheel extended in this photo, on a plane where everything is done
to reduce drag and increase speed?

The up lock broke - due to the violent pitch up.

Same thing happened to Bob Hannah, but happened while "all" that
resulted was a quick 10G climb and a short blackout.
And, he quit after that.


Dave

I've been thinking about this situation. A trim shouldn't EVER be
holding back a violent tendency for a plane veer off! If you've
modified a plane that wants to pull a certain way FIX the problem
don't lean it all the way on the band aid. & this has happened
before?

Cock the vertical stabilizer like is a given for the vertical. If you
still have to trim it, do it for the lower speeds. Its an unlimited
race plane, make it fly like **** slow and straight fast.

Having the stick yanked out of your hand cause of a trim tab is crazy.


SW

You are overlooking the fact that as speed changes then so does lift
and drag and torque, in a propeller driven airplane, and center of
gravity changes dependent on load. There has to be some mechanism to
balance these forces.

These changes are rather large - air pressure at, say 500 mph, is
approximately 25 times that at 100 MPH. A control surface that is
adequate at take off( say 100 MPH) would be 25 times too large at 500
MPH. Or to put it another way, a control surface that was adequate at
500 MPH would be 25 times too large at 100 MPH.

Cheers,

John B.