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Helicopterfriend
Joined: 11 Sep 2008
Posts: 1653
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Ztex
Joined: 28 Aug 2007
Posts: 654
Location: DFW - GKY
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 Posted: Tue Sep 20, 2011 9:35 am Post subject: |
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Here's a post from the Key forum that tries to explain this incident.... I do not believe the photo was tampered with to remove the pilot...
http://forum.keypublishing.co.uk/showpost.php?p=1803173&postcount=149
| Quote: | Just to add a comment regards trim and the effects on the course:
The racers are all trimmed prior to entering the course with a large nose up trim bias, the idea being as they approach the race speeds they can relax the push, as the trim will be correct for the speeds, 400 plus, so one less item to think about, in what would be a pretty intense environment.
The in flight speed range of GG would be about 140 kts to 500+ kts, so it is acceptable to preset a high speed trim, while still accelerating, compensating for the required push until on the course.
in racing, as opposed to most normal flying, the combination of the angle of bank and the need to fly a line with increasing speed means you are using bottom, not top rudder in turns, and you are pushing the nose down in a turn with rudder, and when straight with trim, (elevator) this is opposite to normal input but required for the course.
The downside is exactly what has now probably happened twice, if the trim lets go at speed, the now untrimmed elevator will bias due speed to where it would go if the trim was not applied, full TE up, (nose up effect), and this then creates a situation of "see what wins", with the options being, Flutter, control system structural failure, high speed stall, or full deflection, with resultant effect,
in this case it appears the elevator was powerful enough and mounted securely enough to force a rapid change of angle of attack, with the following effect,
1: 10+ G immediate pull, pilot goes to sleep
2: Tailwheel uplock failed (main gear hangs in there, stronger uplocks)
3: deformation of the rear fuselage
4: rapid climb uncontrolled with a slight angle of bank still induced (he was still in a slight LH turn)
5: its a laminar flow wing, so it describes a parabolic arc, comes over the top, and due the still applied bank, comes down the other side, as lift once again increases, it starts to pull out of its dive, but not enough and hits at about a 75 degree down line.
6: He may well have woken up during this, as there would have been at most 3-4 G at the top of the arc, but by then he was probably well below the canopy rails, definately confused, and since he does not appear to come back up, maybe his seat had broken, which would mean he could not really get back up to see where he was.
I am not in any way playing NTSB here, this is merely my thoughts, and just commenting on the evidence, both written and video shown to date.
I have I never flown an unlimited on the course at Reno.
(However I have raced at Reno in the Biplane class, so I have a small insight into the various factors on the course)
This is mainly intended to expand on the trim issue a little, as some have asked.
Last edited by Moggy C; 20th September 2011 at 11:00. Reason: Small correction of typo for sense. |
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There I was at 20,000 ft, upside down and out of ammunition. |
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