Warbird Information Exchange

I am new to this forum, but a friend pointed me in this direction to provide some information to this forum from one who has been involved with Texas Air Aces as a pilot for the company.

Briefly, my background includes 21 years flying F-4s, F15s and A-10s as well as being involved with pilot requirements development on the F-22. After I retired, I lucked into getting involved with the Texas Air Aces and meeting Don Wiley. I have flown there for the last 8 years in both the TAA side and Aviation Safety side of the operation.

The pilots for both these companies are highly experienced military pilots and understand the importance of flying within the Energy Manevering envelope. In fact, in every BFM briefing, the EM diagram envelope is discusssed. In every flight I ever flew with the company the EM envelope was adhered to.

Flights supporting Aviation Safety Training (unusual attitude training) followed the same guidelines.

Since the accident in Atlanta, a conscience decision to fly at lower G profiles was instituted at TAA. In fact, we found lower g profiles worked better for the enjoyment of the customers paying for the experience. The profiles for the unusual attitude training are normally less than 3Gs, so we all felt those profiles were not an issue and weren't contributing to aircraft fatique.

I realize there are plenty of T-34 owner upset at the BFM companies, TAA in particular. However, after seeing two good friends killed in similiar accidents, I think the FAA and NTSB need to look beyond the single dimensional problem of the affect of g loading on the wing structure. I believe the problem the BFM and aerobatic community may have is a frequency issue. TAA and Aviation Safety fly 3 or 4 times in a day. Even at lower g's well within the envelope of the airplane, this frequency of flying must be taking a toll.

As one writer expressed earlier, maybe the focus should be on the folks flying near the edge of the envelope and with higher frequency.....and leave the weekend crowd an out for future expensive mods they may not even need.

Anyway, I will appreciate any comment others might have and will do my best to give my perspective on the problem from someone intimately involved.

Hello Bubba.

Thanks for dropping in, I completely agree with you!

Let's find a way out of this.

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Olivier Lacombe -- Harvard Mk.4 C-GBQB

HI :CURTISS HAD PROBLEMS WITH PILOTS OVER G ING THE SB2C WHICH RESULTED IN BUCKLING,OR TEARING THE OUTER WING PANELS OFF.THEIR CURE FOR THE PROBLEM WAS TO ADD A RATHER HEAVY COUNTER WEIGHT AT THE BOTTOM OF THE STICK TO MAKE IT PHYSICALLY IMPOSSIBLE TO OVER STRESS THE AIRFRAME THIS ENDED THE PROBLEM .WOULD THAT BE A OPTION WITH THE T-34?HOW MUCH CONTROL DOES THE INSTRUCTOR HAVE OVER THE INEXPERINCED PILOT IN THE OTHER SEAT THATS DOING HIS BEST TO GET A SHOT AT HIS ENEMY?THEY ARE NOT COMPUTERIZED SIMULATORS,YOU CAN TEAR THE WINGS OFF!IT MAY NOT COME OFF ON YOUR FLIGHT BUT MAYBE DOWN THE ROAD THAT DAMAGE SHOWS UP ON SOMEONE ELSES FLIGHT WITH TRAGIC RESULTS.ARE THEY BEING PUSHED TOO HARD?LETS HOPE THEY CAN FIND A CURE FOR A VERY SCAREY PROBLEM THANKS MIKE

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IF YOU CAN FIND IT WE CAN FIX IT

Good Questions Helldiver....I don't know if you can counter balance the stick...I doubt it. However, an experienced air to air IP knows when the customer can slop the stick and when he needs to use back seat override. Obviously, the faster one goes the more sensitive the stick and less throw of the stick one needs to over g. At low speeds, no real problems. Experienced instructors do know these limits and keep the customer within the limits. The reality of fighting T-34 v T-34 is that after the first turn, your g available normally is less than 3-4 since the airspeed is generally decreasing in a turning engagement.

Bubba

Here is a metal fatigue primer for those that are interested.

At a certain stress level and below, steel can be cycled indefinitely. Above that stress level, fatigue damage accumulates. Aluminum on the other hand accumulates fatigue damage regardless of the stress level.

Ergo, a lot of low stress cycles in aluminum can equal the same fatigue damage as a few higher stress cycles.

Another detail is that if you cycle metals in tension only, the fatigue damage is less than if you switch between tension and compression. This means that a Bonanza spar cycling between 0 and +2 g stress levels will last longer than one cycled the same number of times between -1 and +1 g.

Yet another consideration is the fact that holes and other design details can create stress risers which accelerate fatigue damage and can lead to rapid crack growth/failure in areas of high stress. Corrosion, as well as a phenomenon known as stress corrosion cracking are problematic in some aluminum alloys more so than others.

The bottom line is that this is a very complicated issue. The Bonanza series was designed before all these factors were well known. There was probably no fatigue analysis performed at all in the development of the Bonanza (1946?), and perhaps not in the T-34 either.

If you fly ACM style aerobatics to the limits in the T-34 manual, you will accumulate fatigue damage much more rapidly than you would flying the non-aerobatic rated Bonanza models to the Standard Category limits in the Bonanza manual.

If you fly very smooth aerobatic displays like Julie Clark does, a T-34 would probably last indefinitely. On the other hand, the V-Tail Bonanza had a major AD Note come out some years ago that required most to have modifications to prevent the stabilizer leading edges from folding up- this after they had been in service for some 35 years. And that had nothing to do with fatigue damage.

We'll just have to wait for the analysis of THIS FAILURE to see if this is the same problem or another. The two failures may in fact be unrelated.

Well said bdk!

And the latest from the FAA...

http://www.warbirds-eaa.org/news/2004%2 ... ution.html

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It was a good idea, it just didn't work.

bdk,..Thanks for your excellent explanation. After reading the AD Saturday this may be a whole 'nuther thing or a combination...it's
wait and see now.

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He bowls overhand...He is the most interesting man in the world.
"In Peace Japan Breeds War", Eckstein, Harper and Bros., 3rd ed. 1943(1927, 1928,1942)
"Leave it to ol' Slim. I got ideas...and they're all vile, baby." South Dakota Slim
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DBF

Very good BDK.