T-34 crash

On 13 Dec 2004 14:08:10 -0800, "Michael"
wrote:

Richard Russell wrote:
AVWeb has a story out today saying that the wing failed in an area
that was totally different from any of the previous failures and
different from the fix the AD covered.

That's not good news for T-34 owners.

The only good news for T-34 owners would be if the FAA recognized the
real problem. The real problem has nothing to do with the airplane.

The T-34 is not a fighter. It is not designed to take the stresses of
ACM. It is designed to perform some limited aerobatics, and if flown
within those limitations it will never have a problem - or at least
none ever has been a problem.

The Baron spar modification makes the airplane a little stronger in a
crucial area - but it does not turn what is a limited-capability
aerobatic trainer into a fighter. It can't be done. Unfortunately,
given the way these planes are flown, nothing less will do.

I hate to speak ill of the dead, but in this case there is no
alternative. Anyone who has ever observed these weekend warrior antics
and knows anything at all about aerobatic flight can easily see that
these planes are ROUTINELY flown outside the design envelope. It's the
responsibility of the safety pilot in the back to keep the plane within
the envelope, but that doesn't happen. In fact, in the first (US)
accident, there is actually a voice recording of the safety pilot
encouraging the pilot up front to be more agressive - seconds before
the wing came off.

Unfortunately, the FAA insists on treating the weekend warrior
operators and the private owners the same. All T-34's are now grounded
because of the antics of a few who should have (and probably did) know
better.

Michael

I agree. The Air & Space article acknowledged the efforts that many
made to separate "normal" flying from the combat simulation programs.
The FAA was not receptive to that argument. I don't know any of the
victims of these events but I have to wonder how, in light of the
history of these wing departures in high stress situations, they could
continue to expose themselves and their clients to this unacceptable
(to me) risk. I understand that my observations are not based upon
scientific data but it seems clear that the planes are not up to the
task.
Rich Russell

Dave Hyde wrote:
How many g's are required for the "gentlemen's" ACM routinely flown
by these outfits?

In the T-34 accident last year, a video recording showed the aircraft
on the INSIDE of the turn (the one that didn't lose a wing) pulling 5
gees - in a turn. I have no idea what is required - but 5 gees with a
rolling component is excessive.

Saying and doing are two different animals. Since you seem
to give some import to this comment, how many g's did the
'student' apply as a result of the comment - asymmetric
or symmetric?

Enough to pull the wing off.

Dance around this all you want - these weekend warrior operations
account for a minority of the flight time of T-34's, but they account
for 100% of the lost wings. It's not the airplane - it's the
operation.

Michael

The Air & Space article acknowledged the efforts that many
made to separate "normal" flying from the combat simulation programs.
The FAA was not receptive to that argument.

The FAA is, unfortunately, pretty top-heavy with retired military -
especially in the airworthiness portions of it. The operators of these
weekend warrior operations are also mostly retired military. Because
of this, the FAA is reluctant to take action against the weekend
warrior operations, and instread blames the plane.

The second crash (first at Texas Air Aces) was a particularly egregious
example of this. It was well known (based on maintenance records) that
the plane did not have the AD complied with, and while at first some
claimed aerobatics were not being done, the video from the other plane
put paid to that - the plane was being overstressed. Despite this, the
entire fleet was hit with additional (and unnecessary) AD compliance
burdens while Texas Air Aces continued to operate.

This was followed by an investigation at the Houston FSDO, alleging
that Texas Air Aces was operating improperly and that the Houston FSDO
knew about it. Some people were fired or reassigned over this, but in
the end it was just another FAA investigation, followed by business as
usual. I caused the one person at the FSDO who actually knew something
about aerobatics to quit in disgust.

If the FAA were to separate out the T-34's being used for ACM as a
separate group (the one responsible for all the accidents) this would
be tantamount to shutting down the weekend warrior operations that use
it. The pool of T-34 owners might be big enough (or not) to support
the development costs of a 'fix' but the much-smaller pool of weekend
warrior operations certainly isn't big enough. Also, since everyone
knows this sort of damage is cumulative (especially with Aluminum
spars) their planes would be pretty much worthless. That would be a
big enough hit to bankrupt most of them.

Because my home field is also home to the acknowledged T-34 expert
mechanic in the area (he also owns his own T-34), I've met quite a few
T-34 owners and know a couple of them fairly well. Their planes all
had their spars inspected after the first accident, and everyone knows
there's nothing wrong with them. Let's just say these weekend warrior
operations are not exactly popular in the T-34 community.

Michael

Michael wrote

In the T-34 accident last year, a video recording showed the aircraft
on the INSIDE of the turn (the one that didn't lose a wing) pulling 5
gees - in a turn.

So how many g's was the mishap airplane pulling?
The only correct answer you can give is "I don't know."

...how many g's did the
'student' apply as a result of the comment - asymmetric
or symmetric?

Enough to pull the wing off.

That's apparent - now was it below or above the limit?

Dance around this all you want...

No dancing here - I'm pointing out, with your help, that
you have little in the way of facts or experience, but
plenty of supposition and disdain for several parties
involved.

It's not the airplane - it's the operation.

Simply writing "ACM" on a flight card in the airplane
does not cause the wings to fall off. Was the stress
at failure above or below design limits? Until you can
answer that question factually and support it quantitatively
everything else is just throwing stones.

Dave 'innuendo' Hyde

Dave Hyde wrote:
In the T-34 accident last year, a video recording showed the
aircraft
on the INSIDE of the turn (the one that didn't lose a wing) pulling
5
gees - in a turn.

So how many g's was the mishap airplane pulling?
The only correct answer you can give is "I don't know."

Bzzt, wrong, but thanks for playing.

Since the accident aircraft was keeping up, and was on the outside of
the turn, the correct answer is more than five. That's simple physics.
And since it was in a turn, there had to be a rolling component
involved as well at some point.

Keep dancing.

Michael

"Michael" wrote in message
ups.com...

Since the accident aircraft was keeping up, and was on the outside of
the turn, the correct answer is more than five. That's simple
physics.

If you're saying that the aircraft "keeping up" on the outside of the
turn was at a higher g than the 5g's being pulled by the aircraft in
front and inside of him , you are mistaken.
Actually if the trailing aircraft was "keeping up" he would be at co
speed in the turn, and at co speed, the g would be the same on both
aircraft and the trailer would be the defender after 180 degrees of this
somewhat bad situation for the guy in back. This is why the attacking
aircraft can't be at the same g as the bandit and be "keeping up". The
trailer MUST have closure rate and a Ps advantage on the defender to
acheive an attack curve. This can be in a pursuit curve, usually a lag
curve at lower g with a higher attack velocity, or it can be obtained by
the use of cutoff or arcing inside the plane of turn of the defender. In
other words, the guy behind can't "keep up" by having a higher g. He
can't even keep up pulling the same g as the defender since this puts
them both in the same turn radius. The attacker must maintain a higher
attack velocity than the defender which means that in order to effect
closure and reduce angle off, he has to pull a lower g than the
defender.
Assuming both aircraft have the same Vc (corner velocity) which they do
as T34's , the only possible situation that would put the trailer at a
higher g then the defender as you have stated , would be if he was
pulling lead which would put him in a lead pursuit curve and inside the
plane of turn of the defender at a higher g....therefore no longer
"keeping up" so to speak.
Also, the attacker HAS to have a higher airspeed in the attack curve to
acheive nose/tail separation and angle off, which means, if he doesn't
pull higher g than the defender, HE MUST OVERSHOOT if he's in the plane
of turn of the defender. So if he's back there at all, he ain't at co
speed at the same g, and he has to be pulling a LOWER g, not a higher g
than the aircraft with which he's engaged.


Keep dancing.

Why so nasty to this poster? He's only asking a question. Hell, if
you're going to be nasty, at least give him the right answer :-)

Michael

yeah, I know; The ACM expert! :-)

Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI Retired
for email; take out the trash

Michael oglegroups.com...

Since the accident aircraft was keeping up, and was on the outside of
the turn, the correct answer is more than five. That's simple physics.
And since it was in a turn, there had to be a rolling component
involved as well at some point.

How accurate was the accelerometer? What was the load at the
time of failure,. As before, you don't know. You also don't
know if it was above or below the spec stress. The repetetive
theme of the thread is "you don't know". Neither do I, but I
don't claim to, nor do I attribute blame.

Dave 'popup' Hyde

Dudley Henriques wrote...

Why so nasty to this poster? He's only asking a question. Hell, if
you're going to be nasty, at least give him the right answer :-)

Michael and I have discussed accident investigation techniques
and results both here and face-to-face. Let's just say we're
at opposite ends of the opinion yardstick. And I didn't take
it as particularly nasty.

Dave 'opinion poll' Hyde

Big John wrote:

Another T-34 crashed today here in Houston killing the IP and
student.Was from the company that has air combat and upset training.

Eye witness heard a report and saw a wing that had separated. They had
a similar accident (wing separation) just a year ago that killed the
owner of Company.

Not sure if this bird had the FAA wing mod or not.

My condolences to the families of the pilots.

Big John

I TOLD them not to use real ammo.

Dudley

Long time no talk. Health not good.

You explaination in your post is confusing and in many cases wrong.

To hit a target you have to put the pipper on the aim point which
remains the same as long as the target maintains the same airspeed.
So you aim at the same point when you are 90 degrees or 10 degrees
off. Sight picture looks diffeent but aim point remains the same. Duck
hunters will understand this.

If you fall into trail (say 1000 feet behind target) and put the
pipper on the target you will miss. If you close until all you see in
the wind screen is target then you can point and shoot and kill. Many
of the high scoring Aces flew into that postion to get kills. Others
of course got most of their kills in a pursuit curve (higher angle
off).

If you are flying the same diameter circle as the target and not
closing then you will be pulling the same "g's" as the target. From
that positon to get a kill you have to decrease the diameter of circle
you are flying to get on the pipper on aim point and that makes you
pull more 'G's" than the target.

If you got a 'fur ball' going, then the vaying speed and aim point
causes the 'G' loading to vary through out the fight.

All that being said, I don't remember the latest accident being in a
combat simulation? Just upset training which should be get wings level
right sideup and then recover from dive. No rolling 'G's' in this.

Fly safe and very Merry Xmas to you and yours,

Big John
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~``


On Wed, 15 Dec 2004 04:52:11 GMT, "Dudley Henriques"
wrote:


"Michael" wrote in message
oups.com...

Since the accident aircraft was keeping up, and was on the outside of
the turn, the correct answer is more than five. That's simple
physics.

If you're saying that the aircraft "keeping up" on the outside of the
turn was at a higher g than the 5g's being pulled by the aircraft in
front and inside of him , you are mistaken.
Actually if the trailing aircraft was "keeping up" he would be at co
speed in the turn, and at co speed, the g would be the same on both
aircraft and the trailer would be the defender after 180 degrees of this
somewhat bad situation for the guy in back. This is why the attacking
aircraft can't be at the same g as the bandit and be "keeping up". The
trailer MUST have closure rate and a Ps advantage on the defender to
acheive an attack curve. This can be in a pursuit curve, usually a lag
curve at lower g with a higher attack velocity, or it can be obtained by
the use of cutoff or arcing inside the plane of turn of the defender. In
other words, the guy behind can't "keep up" by having a higher g. He
can't even keep up pulling the same g as the defender since this puts
them both in the same turn radius. The attacker must maintain a higher
attack velocity than the defender which means that in order to effect
closure and reduce angle off, he has to pull a lower g than the
defender.
Assuming both aircraft have the same Vc (corner velocity) which they do
as T34's , the only possible situation that would put the trailer at a
higher g then the defender as you have stated , would be if he was
pulling lead which would put him in a lead pursuit curve and inside the
plane of turn of the defender at a higher g....therefore no longer
"keeping up" so to speak.
Also, the attacker HAS to have a higher airspeed in the attack curve to
acheive nose/tail separation and angle off, which means, if he doesn't
pull higher g than the defender, HE MUST OVERSHOOT if he's in the plane
of turn of the defender. So if he's back there at all, he ain't at co
speed at the same g, and he has to be pulling a LOWER g, not a higher g
than the aircraft with which he's engaged.


Keep dancing.

Why so nasty to this poster? He's only asking a question. Hell, if
you're going to be nasty, at least give him the right answer :-)

Michael

yeah, I know; The ACM expert! :-)

Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI Retired
for email; take out the trash