Reno P-51 Crash – Was it the Elevator Trim? [NEWS]

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Reno P-51 Crash

Was it the Elevator Trim? [NEWS]

Friday’s shocking P-51 crash at Reno, Nevada claimed even more lives than it was initially anticipated. The official death toll has now risen to ...

Friday’s shocking P-51 crash at Reno, Nevada claimed even more lives than it was initially anticipated. The official death toll has now risen to 9: seven people died on the tarmac, including the pilot, and two more died in hospitals. Added to that number are 67 injured, many of them in critical condition.

The team of investigators continues to comb the accident site where the P-51 “Galloping Ghost” racer literally disintegrated into a cloud of debris.

Reno 2010 Day 1 -4

[photobunny, via Flikcr/CC]

A National Transportation Safety Board member confirmed yesterday that one of the scenarios under investigation is whether the plane’s apparently damaged elevator trim tab, whose breaking apart was captured in a photograph by one of the onlookers, played a role in the nosedive crash.

The disaster struck during the third lap of an eight lap Unlimited Gold race, when the Galloping Ghost, piloted by Jimmy Leeward, was flying in the third position. Suddenly, the plane pitched violently upward, reverting from its course into an erratic barrel roll followed by a near-vertical dive. The aircraft remained at full power throughout the manoeuvre and smashed violently into the tarmac only meters ahead of the grandstands, with disastrous results.

The said photo of the Galloping Ghost¬†showing the aircraft upside down prior to the accident reveal that the port elevator tab was missing. During the race, most of the pilots set the elevator trim tabs straight down. Sudden loss of a tab at high speed could have caused the loss of pilot’s control over the plane. In a situation like this, the stick force that the pilot has to apply to hold the nose level changes drastically, causing the plane’s nose to rapidly rise. ¬†At a speed of almost 500 mph, the g-forces could build up very quickly, possibly faster than the pilot could compensate. This type of incident happened to another racing P-51 in 1998.

The Galloping Ghost was an air racing veteran, remembering the times of the Cleveland Air Race. Under the ownership of Jimmy Leeward, the aircraft was extensively modified, featuring a Rick Shanholtzer-prepared racing Merlin and a water boiler cooling system. Removing the air scoop and radiator has substantially reduced drag, however limiting the range of the aircraft to the amount of consumable water in the cooling tanks.

13 Comments | Add New

By David Larkin  |  2011-09-24 at 22:15  |  permalink

See:
http://macsblog.com/2011/09/why-the-trim-tab-on-a-racer-matters-so-much/

David Larkin

By Barry Gillingwater  |  2011-09-30 at 01:51  |  permalink

David is quite right about the operation of the elevator trim. After reading all of the available text about this incident I would like to add something of an opinion. In nearly 30 years of flying – mostly instructing (RAF A2 cat and civilian QFI), I have participated in only two ‘air races’. These were nothing to do with the professionals who race at Reno but simply a bit of fun at local airshows put on as crowd pleasers. From what I recall the high throttle setting (for that read ‘open wide’) made the nose of the a/c want to rise so forward elevator trim was applied to ease the stick load on the pilot. This was OK for the straight legs (in between the pylons) but when rounding the pylon turns a steep bank angle was applied which necessitated a fair amount of back pressure on the stick to maintain the prescribed (low) altitude during the turn and stay in sight of the crowd. The ‘pylon’ turns were effectively max-rate turns, during which neither the throttle nor elevator trim setting were altered, as all of my concentration was needed to keep my ‘line’ in rounding the pylon and to maintain a safe amount of daylight between the a/c and the ground. I had neither the time or inclination to fiddle with these controls having my hands full just flying the a/c accurately. During the turn my back pressure on the stick would have acted in opposition to the forward elevator trim setting, a situation which would have been relieved as I snapped out of the turn and resumed straight and level flight on the subsequent leg. The point I am making is that during the straight legs the elevator trim control surface is ASSISTING the pilot, but rounding the turns it is RESISTING the pilot. If you apply this example to an air race where there are four pylon turns this will give four straight sectors alternating with four turns, multiply this over ten laps and you will have achieved a situation where (4 + 4) x 10 = 80 control reversals will happen. To put extreme pressure on an ancillary flying control (the elevator trim tab) in the manner of 40 movements one way, alternating with 40 movements in the opposite direction, for the duration of just one race seems to be inviting metal fatigue (I’m assuming that all of the elevator trim system components are made of metal). To use the same basic (ageing) airframe over many years as a dedicated air racer would seem to require an awful lot of maintenance and inspection (e.g. component crack testing) on this area of the primary flight control just because of the task (air racing) the a/c is used for. I have no idea whether they modify these aircraft by fitting servo-assisted trimmers so they can be adjusted at every pylon turn (in and out) but I rather think they wouldn’t have the time due to the high speeds they operate at and the small time window to alter the trim to ease the problem. They probably just push harder on the straight bits and pull high ‘G’ during the turns, which means the elevator trim tab just has to ‘put up with it’. None of my remarks have been intended to trivialise the victims of this incident, I just wanted to add a different dimension to the technical discussion.

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