Bertie the Bunyip wrote:
Dudley Henriques wrote in
:

Bela P. Havasreti wrote:
On Sun, 18 Nov 2007 14:22:58 -0600, Big John
wrote:

On Sun, 18 Nov 2007 13:51:53 +0000 (UTC), Bertie the Bunyip
wrote:

WJRFlyBoy wrote in
:

On Sun, 18 Nov 2007 08:12:31 +0000 (UTC), Bertie the Bunyip wrote:

This is the one I mean to post Dudley. Was having some trouble
with Youtube due to a plug-in I think..
http://www.youtube.com/watch?v=Y7eYhlm9FJ8
Can you assess the problem?
What, with my browser or the accident?

The T-6 passed 90 deg (and even earlier) with his nose below the
horizon. He could have rolled back and saved it at that point, but
he continued around in the now awkward position of having to
prevent further altitude loss with excessive neg G which slowed him
considerably and further skewed the airplane's. The exit half was a
classic dish. Everybody does 'em sometimes.... Trick is to
recognise a roll that's going to produce one early enough to
abandon it. This guy didn't.

The You tube extension add-on, I have no idea, but it's made a mess
out of my youtube fun!



Bertie
Bertie

I made some comments on another post on this accident which was
before the video of the accident was posted.

I have looked at the strip probably 50 times and can't come up with
what I believe is a accurate analysis of what all happened and why.

1. Bird was in a shallow dive and picking up airspeed, above cruise,
when strip starts. This is a good entry technique.

2. Bird bottomed out and nose was raised above the horizon before
roll started. Again good technique.

3. After first 90 degrees of roll nose had dropped to at least level
or very slightly nose down.

4. After 180 degrees of roll nose was definitely below the horizon.
Not in a dive but shallow enough that continuing roll rate should
have allowed completion of roll before bird hitting ground.

5. After 270 degrees of roll bird made almost a square corner port
turn and shortly after hit the ground almost flat 90 degrees off
line of flight.

6. It did not look to me like he dished out but I don't know why the
bird made the rapid 90 degree turn off line of flight. My experience
with dish out of roll, in T-6, bird ended up at max 30 degrees off
line of flight.

7. Assuming video strip was real time, the roll was a pretty rapid
slow roll. My slow rolls were about half the roll rate of this bird.

8.Roll was against torque, which would have slowed roll down without
extra aileron.

9.Either you or Dudley talked about G forces slowing bird down. I
didn't see any large angle of attack which would be required to slow
bird down.

10. Looking at bird in video, I didn't see any reduction in airspeed
until about the time it made the 90 degree turn before impact.

Lots of comments but can't give a hard analysis of what happened
from start to finish.

Big John
If I recall correctly, the pilot of the accident aircraft borrowed
that T-6 for the accident flight (his T-6 was down for maintenance,
something like that...). The story went that his T-6 had the "high
throw" aileron bellcranks, but the borrowed / accident T-6 did not.

Bela P. Havasreti
The 6 had 2 choices of bell cranks on the ailerons. One was a 29up/15
down and the other a straight 15/15 if I recall.

If the accident pilot was used to the roll rate and roll inertia
resulting from a roll set initiated at his usual entry airspeed
(aileron dynamic pressure) and rolled the borrowed aircraft with the
asymmetrical aileron setup this could possibly explain a great deal to
me as a display pilot.
For a given airspeed, the aileron drag produced by the 29/15 setup
would not have been what he was instinctively expecting and that could
easily have spooked him as the roll commenced causing the control
mis-application and confusion that seemed obvious from the crash.

Absolutely. It would have been like flying an almost entirely different
airplane. There's a lesson there, alright..


Bertie

With this information, I honestly believe this is what got him. The
asymmetrical cranks would buffet the ailerons in a full stick throw and
from the film, he had considerable aileron in play judging from the roll
rate I saw. If he got "unexpected" results from the lateral stick throw
and felt some aileron buffet he wasn't expecting, this combination could
have produced the exact result we saw on the film.
Low altitude rolls are one area of flight where if you begin feeling
something out of place during the roll, it could easily kill all but the
most highly disciplined display pilot. Even then, it could be a crap
shoot picking a result.
You try to prepare for everything in your training as a display pilot,
but there's always the unexpected. If that happens, even professionals
can get that split second brain freeze where you try desperately to sort
it out in the nano-second you have to do that.
My guess is that this poor guy just got a split second behind what had
to be done and the airplane started flying him instead of the other way
around.
It happens, and I've seen it happen to some of the finest pilots I've
ever known.
Sad fact of life in this venue unfortunately.

--
Dudley Henriques