On Wed, 21 Sep 2011 17:59:08 -0500, Sunworshipper SW@GWNTUNDRA
wrote:

On Wed, 21 Sep 2011 12:04:04 -0500, Richard
wrote:

On 9/21/2011 8:58 AM, Sunworshipper wrote:
On Wed, 21 Sep 2011 05:40:36 -0700 (PDT), Dave__67
wrote:

On Sep 20, 10:48 pm, 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


It's just not possible for aircraft with such large speed ranges.
(And yes, that includes the airliners as well. They work the same way)

Maneuverability and stability are opposite ends of the same string.
A really stable aircraft will not be very maneuverable.
A maneuverable aircraft will not be very stable.
That is, of course, without modern fly-by-wire control systems.
But even then, the basic aerodynamics are that way.



This is a good synopsis, if you are really interested.
soliton.ae.gatech.edu/people/lsankar/AE1350/Lecture.11.ppt

?



Or if you really have the balls for it...
http://ocw.mit.edu/courses/aeronauti...rse-materials/


This is interesting, one can take courses for free?


Take particular note of Static and dynamic stability, static margin, and
the effects of increasing or decreasing stability margins.


Sounds good and all, but I don't believe it. Loosing a trim tab
shouldn't cause multiple G forces.


SW
Believe it or not - at that speed it WILL.