Re: What is the cockpit environment like?
The vertical fin of Miss Ashley II was a standard P-51H fin built from blueprints. The rudder was metalized but otherwise stock. The aircraft had been flying for years when it went in. There was never any flutter detected prior to the accident. Of course the P-51H was also well proven. To be fair they had just created a radical NACA scoop based belly scoop and I wondered if that had contributed but I had heard repeatedly from folks I trust the trim tab was the core issue.
I was close to Bill while MA-II was being built. I had done some engineering on the plane when it was under construction to do HP/air speed projections and even talked to Bill about the challenges of getting an "H" fin built as the alloy used in the spar was not easily available. While some changes were associated with the Lear horizontal there was never flutter prior in MA II or Vendetta prior.
Failure cascade as I remember was trim tab, rudder flutter, vertical fin failure, tail cone failure, loss of vertical stab caused extreme negative G pitch down, wing failure at spar repair... the rest we all know. It seems like most of the video showed this clearly but last I check most of it has been pulled down.
Spacegrrrl
Originally posted by AirDOGGe
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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.
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.
I was close to Bill while MA-II was being built. I had done some engineering on the plane when it was under construction to do HP/air speed projections and even talked to Bill about the challenges of getting an "H" fin built as the alloy used in the spar was not easily available. While some changes were associated with the Lear horizontal there was never flutter prior in MA II or Vendetta prior.
Failure cascade as I remember was trim tab, rudder flutter, vertical fin failure, tail cone failure, loss of vertical stab caused extreme negative G pitch down, wing failure at spar repair... the rest we all know. It seems like most of the video showed this clearly but last I check most of it has been pulled down.
Spacegrrrl
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