Trying to catch up. Before this tragedy happened, I had been talking to some teams about reducing compressibility drag on the Mustang Unlimteds, so I might have some unique contributions.
Haven't had time to study the video frame-by-frame but can comment in areas. Like everyone here, still putting the pieces together.
- "Could it occur, but not for long enough for the aircraft to actually stall at that G load and relieve itself?"
Dynamic stall can result in higher CLmax than the FAA demonstrated one knot/sec deceleration to the stall by hysteresis. Though on some other boards, there are claims of the telemetry being limited to 8g's. Don't know if we'll get the right number until the report, unless someone takes the time to convert the geometric flight path to g's. Since the tailwheel pops out before wings level, this might not capture the max.
- Remember a report in the past about older people being able to handle g better than the younger ones if they have any hardening of the arteries since the airteries don't expand as much to accept blood. This probably wouldn't matter much at 10+ g's, but the discussion should preclude age.
- Leaning towards the structural failure causing the left wing drop since wake turbulance would be unlikely since the wind was coming from the direction it was and was strong from the flags flying in various videos.
- "Roll Rate on this a/c is rapid, far higher than the factory model with ten feet less span. Similarly, the ailerons are half length, and it would be interesting to know if they were clipped Out/In, or In/Out. This is critical, since ailerons are airfoils, and subject to STALL just as any other."
Roll rate capability is a function of wing span-to-aileron span, and would be reduced due to the clipped wings at the tip, but at these q's, the airplane had plenty of control authority. Ailerons don't stall like wings since the leading edge is protected by the slot, but the upper surface can separate at high enough deflections.
- The racing Mustangs have an aft cg, so the elevator is deflected for nose down moment at race speeds. Some of the guys have changed the incidence to alleviate this requirement. Leeward had the one port trim tab. Voodoo had the elevator shear the torque tube fasteners on the lost trim tab side. Probably from the violent act of the trim tab fluttering and departing.
- The trim requirements in the turns and straights tend to balance out due to the aft movement of the center-of-pressure due to a shock wave forming on the inboard wing at 4 g's in the turn. Haven't analyzed it yet, and Leeeward was banked pretty good in the turn, but 6 or 7 g's probably wouldn't cause Mach buffet, looking at the pressure distribution at 4 g's. Yes, the Unlimteds are seeing compressibility drag due to the original subsonic airfoil selection.
This seems like a forum with informed, and talented individuals, and will try to contribute as I read through the thread.
Last edited by ClippedCub; 5th Oct 2011 at 01:05.