T-6 accident

Big John wrote in
:

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

WJRFlyBoy wrote in
t:

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.

OK, it's kind of hard to see it in relation to he horizon for a lot of
the roll. My own feeling is the nose was down too far during the first
quarter and then he was well to nose low during the inverted portion and
knew it, pushed hard and drew some drag, then panicked and tried to get
out with hard top rudder too early and pulled hard as soon as he passed
90 deg roll on the back side. It's been a while, but it;s a classic
student panic recovery from a botched roll.

Bertie