What is the cockpit environment like?

[spacegrrrl]

One thing that I've been obsessing about since Friday is what the experience while flying the unlimited racers at speed is like. Is there so much vibration, shaking and commotion that early indications of flutter would be hard to notice? Does the plane get bounced around enough that control issues might be hard to detect?

I'm actually asking for a serious reason, we have lost two planes to trim tab failure (and almost several more). I'm wondering if there is some sort of instrumentation that could be fitted to alert the pilot there might be an issue developing. Is there something that could have told Jimmy or Gary something was going wrong before it was too late?

The engineer in me wants to find a way to never ever have to see something like this happen again. These days with all the mobile computer power and low cost sensors there has to be something that could be monitoring the air frame for out of the ordinary cyclic vibrations and other anomalous events. It could even be something as simple as something that correlates the actual surface position to the expected base on the stick and trim position.

Spacegrrrl

[eeyore]

Re: What is the cockpit environment like?

I know it's a tough ride. I looked at my scale drawings of air races and concluded elevator trim tabs are left over from war time use. Why not elimination them Tsunami didn't use one.

[Dash]

Re: What is the cockpit environment like?

Trim tabs are designed to allow the aerodynamic pressures to be lessened and allow the plane to be hand flown. It has nothing to do with being a warbird. I do not know what Tsunami used, but I feel sure it did have trim. There are a few ways that I have seen this done: trim tab (servo or anti-servo), a trimable elevator where the entire elevator moves for trim, and a flying tail where the entire horizontal stabilizer can be moved and trimmed. Even if you do away with the tab, flutter can occur in the primary flight control surface. The onset of flutter can occur so quickly with catastrophic failure, that indicators would do no good. Besides, the pilot wouldn't be very safe looking at gauges rather than keeping their eyes outside and flying the plane.

[Ken Adkins]

Re: What is the cockpit environment like?

Reading many of the press accounts today, they mention amateur videos that show the trim tab falling off the Ghost during the race. Has anyone seen these?

[BKB]

Re: What is the cockpit environment like?

Space-

I asked Will Whiteside that very question.

He was gracious enough to come up and reply.

Give me a bit of tome and I'll see if I can find it and provide you with a link to that thread.

I watched with great admiration the videos that Jason posted with lots of footage of Will at work.

There is also some in cockpit video of Skip on his 6 lap record run.

It doesn't seem to be too rough a ride(at least to me anyway)

It does seem to be VERY fast though.The ground rush is pretty amazing.

Found the link and add it. http://www.aafo.com/hangartalk/showthread.php?t=8547

Brian

[spacegrrrl]

Re: What is the cockpit environment like?

Thanks for the reply BKB, that was very informative!

Spacegrrrl

[mgk77]

Re: What is the cockpit environment like?

This should give a good idea of the cockpit environment - http://youtu.be/e2TQ8dJDMFE

It could even be something as simple as something that correlates the actual surface position to the expected base on the stick and trim position.

Wouldn't that be similar to what's done on a fly-by-wire setup without the "fly by" part? More like "Monitor-by-wire?"

[AirDOGGe]

Re: What is the cockpit environment like?

...I'm actually asking for a serious reason, we have lost two planes to trim tab failure (and almost several more). I'm wondering if there is some sort of instrumentation that could be fitted to alert the pilot there might be an issue developing. Is there something that could have told Jimmy or Gary something was going wrong before it was too late?
.

Spacegrrrl

Where did you read or hear that a trim tab failure was the reason for the loss of Gary and Miss Ashley II ? The last theory I heard was rudder flutter leading to structural failure of the tail end leading to a pitch down followed by vertical fin separation. I never read anything about a trim tab issue.

[440_Magnum]

Re: What is the cockpit environment like?

Somewhere, either on this site or on Scotty's, there is/was an interview with Tiger where he gave a good and descriptive account of flying Strega at high full race power, atypically free of Tiger-esque winks and comments about "secret ****." From what I remember, he did describe it as unbelievably loud and rough, but I don't know if it would mask other problems. I'm sure you can't hear detonation and other early-warning engine noises, but beyond that???

[spacegrrrl]

Re: What is the cockpit environment like?

Where did you read or hear that a trim tab failure was the reason for the loss of Gary and Miss Ashley II ? The last theory I heard was rudder flutter leading to structural failure of the tail end leading to a pitch down followed by vertical fin separation. I never read anything about a trim tab issue.

I was told the trim tab led to the rudder flutter. What else would you have expected to have caused rudder flutter?

Spacegrrrl

[sandramore]

Re: What is the cockpit environment like?

I was told the trim tab led to the rudder flutter. What else would you have expected to have caused rudder flutter?

Spacegrrrl

I had actually heard the trim tab theory as well.

Btw, one of the tribute videos I posted (the first one, not the "start at 3:30" video) shows Jimmy sitting in Ghost after taxiing in. You can clearly see how much of him would be visible in the crash photos if he were conscious and wrestling with the aircraft. It also give a good idea of how much room he had in front of him had he slumped/leaned/been pulled forward.

[AirDOGGe]

Re: What is the cockpit environment like?

Flutter existed long before trim tabs were even invented. Wings, propellers and other airframe parts can be subject to destructive flutter. It's not just an issue with aircraft either.


In Miss Ashley II's case, the tail end was modified far from stock P-51 form, with a Learjet stabilizer and elevator replacing the North American-made surfaces, if I am correct. I don't know if the vertical tail was modded too, but it's certainly taller than a "D" model's tail. Perhaps from a later model 'Stang?


A change in stiffness of the tail end of the fuselage could result in flutter. A stiffer tail would resonate at higher frequencies than a Mustang's, and a more flexible rear end would flutter at lower ones.


This is why new aircraft are tested for flutter at various velocities, both high at it's maximum and at it's lowest to stalling...to see if any portion of the airframe (not just trim surfaces) would resonate with the airflow at that particular speed and produce some form of flutter.


The tail of Gary's plane was a one-of-a-kind item. It's very possible that Gary hit just the right speed and was struck by just the right turbulence to induce flutter and failure.

I DO recall reading that a video of Gary's crash was watched in slow motion by the NTSB and others. The rudder was seen fluttering at high speed and was said to be very blurred, seemingly almost invisible, a video effect that could occur if it's flutter vibration frequency closely matched that of the video camera's frame rate or a sub frequency of it. This high speed vibration under load could weaken the whole tail section, which failed resulting in a pitch-down and airframe break-up beginning with the wings departing.


I never heard anything about a trim tab separating, anywhere. Was that just an assumption, or is it reported somewhere I can be directed to please? If I'm incorrect, then I WISH to be corrected. If true, then the trim tab would have been found on the track well before where the accident occured, and no theories would be needed...

But if the tab was found still attached to the elevator and intact, then that theory is a dead end. Anyone know? I was there in 1999, but I looked away just before the breakup happened.

[AAFO_WSagar]

Re: What is the cockpit environment like?

It was, indeed, the trim tab, which departed the airplane, following which there was severe rudder flutter, loss of control and structural failure...

We're all fairly high strung here, also mostly in shock. Everyone wants to know exactly what happened, we may never know the details, but it does appear that the dreded loss of trim tab strikes again.

[sandramore]

Re: What is the cockpit environment like?

It was, indeed, the trim tab, which departed the airplane, following which there was severe rudder flutter, loss of control and structural failure...

We're all fairly high strung here, also mostly in shock. Everyone wants to know exactly what happened, we may never know the details, but it does appear that the dreded loss of trim tab strikes again.

Once might be a fluke. Now we know it isn't. A hard way to learn, but this will start the search for solution that will prevent it from ever happening again. I've learned to have a lot of faith in the guys that build and maintain these birds. They'll figure it out.

[AAFO_WSagar]

Re: What is the cockpit environment like?

I never heard anything about a trim tab separating, anywhere. Was that just an assumption, or is it reported somewhere I can be directed to please?

If you read the NTSB report on MAII, the trim tab was the first thing to hit the ground, found farthest from the impact site. As I was told by one of the crew shortly after the initial report, "read the debris field".