RNO Air Races Crash

[ackattacker]

11 now. Unbelievably tragic.

 

[saabcaptain]

When they were reporting the total as 10 yesterday a friend stated that privately sources at the races indicated about 8-9 additional "missing" were likely to be classified as dead once DNA etc. came in so the totals will continue to climb quite a bit. Horrifying.

 

[Erlanger]

This new video is unbelievable. The sound of the impact is shocking.

http://www.cnn.com/video/#/video/us/2011/09/20/von-reno-air-crash-new.kgw?hpt=hp_t2

Another theory about the crash emerges.

http://www.foxnews.com/us/2011/09/2...-broken-seat-aviation-expert/?test=latestnews

 

[808pilot]

Bubbers... You and I must have been sitting pretty close to each other... I was in the box seats just to the west as well... Same thing... When he rolled out of being inverted he was pointed right at us... I shuffled left then right and realized there was no way to judge in a split second what was going to happen... I just stood there in complete shock... That entire flight and crash is on constant loop right now in my mind... Amazing the devastation that it caused... But could have been even worse had he not pulled up what little he did... And the fact that the blast shot out towards the taxiway... Pretty nuts...

 

[HalinTexas]

Todays WSJ echoed these sentiments. They're estimating a 10g uncontrolled pitch-up after the trim tab failed. That would knock out anyone. I would imagine that the seat would fail somewhere between 8-12g's as that would be more than enough for a pilot without a g suit. Also, strengthening a seat beyond that would add weight that they don't want to deal with.

My guess is that he blacked out shortly after the pitch-up. Probably partially regained consciousness at the top of the loop, but maybe not. The g loading at this point and after probably made sitting upright impossible. Notice that this thing was still developing quite a bit of power, if not the same power setting he was using to race.

I suspect that Providence was the factor in determining where the aircraft hit. Amazed that there was no fire whatsoever.

God be with those that were there.

 

[dougdrvr]

This new video is unbelievable. The sound of the impact is shocking.

http://www.cnn.com/video/#/video/us/2011/09/20/von-reno-air-crash-new.kgw?hpt=hp_t2

Another theory about the crash emerges.

http://www.foxnews.com/us/2011/09/2...-broken-seat-aviation-expert/?test=latestnews

The Fox news theory from a GA mechanic is disgusting. They even rotated the photo 90 degrees to fit their story. I realize this aircraft was highly modified but a stock Mustang seat, which I would guess is engineered to well in excess of 12 G, only adjusts in the vertical. The rudder pedals are adjustable fore and aft, not the seat. Typical lack of knowledge from a media organization in an attempt to get out in front of everyone else.

What's amazing is the quality and sharp focus of that photo (in a vertical dive). When I first saw it, I was convinced it was photoshopped and they forgot to erase the tailwheel, but apparently, it legit!

 

[DznFr$$]

I was there also and saw the whole thing from the time of the initial pullup. My point of reference was the west side of the airport facing pylon nine about 100 yards away. He was coming around the last pylon when the aircraft snapped level and then violently pulled vertical, most likely 20 G's. That stress would have caused the tailwheel to fall out. My guess is that he was unconscious from that point. The aircraft continued a vertical climb and right roll until it was pointed straight down and horizontal to impact. At the top point inverted, you can see in the photo that the pilot is slumped forward in his seat face down. The subsequent photos right before impact, he is no longer visible in the cockpit. I agree that his seat and or harness failed because of the violent pitch change, but disagree that he was still capable of flying the aircraft, or that the aircraft stalled. It was producing full power and hit at 300+ mph.

 

[ultrarunner]

Another theory about the crash emerges.

http://www.foxnews.com/us/2011/09/2...-broken-seat-aviation-expert/?test=latestnews

I would theorize the massive G-load as a result of lossing the trim tab could have easily broken seat mounts. No surprise there....

 

[JumpersAway]

A truly sad loss. I know the Reno Air Races are THE reason I'm flying today- went as a kid and got hooked on aircraft at a young age. I hope they are able to rebound and continue, although insurance costs alone will be prohibitive after this.

Several interesting photos on WIX (Warbird Information Exchange) regarding the accident. The sound from the merlin as it hit close in to one of those filming is erie, to say the least.

God speed and my thoughts and prayers go to those lost and affected...........

 

[glasspilot1]

My guess is after much arguing back and forth that air racing will continue. But they'll have to follow what "air shows" have had to do for decades........move the course away from the crowds.

 

[WildcatFan]

The Fox news theory from a GA mechanic is disgusting. They even rotated the photo 90 degrees to fit their story. I realize this aircraft was highly modified but a stock Mustang seat, which I would guess is engineered to well in excess of 12 G, only adjusts in the vertical. The rudder pedals are adjustable fore and aft, not the seat. Typical lack of knowledge from a media organization in an attempt to get out in front of everyone else.

What's amazing is the quality and sharp focus of that photo (in a vertical dive). When I first saw it, I was convinced it was photoshopped and they forgot to erase the tailwheel, but apparently, it legit!

I agree. I doubt the seat failed and I doubt this aircraft has the control authority to fail the seat, but I consider it irrevelent anyway because an unexpected pull up in excess of 9 or ten G is enough to incapacitate the pilot. Fighter pilots sustain 9G only because they are ready for it. Even the G-suit doesnt help if you dont do your part first. You cant play catch up with 9 g's if you aren't on top of it first. Unfortunately, the pilot in the case most likely wasn't part of the equation after the initial pull up.

 

[charlie2]

I have personally experienced GLOC as a back seater in the F-4 during an airshow in El Toro many years ago. Going thru a divorce and was tired and only had coffee all morning are my excuses. After our part of the show was done the pilot reefed on more than the usuall G's during the overhead break and I didn't "wake up" until wings level on downwind so I'm estimating 4 to 5 seconds in la la land. It kind of looks like from high G pull up to impact it wast much more than that so I think you are right about the pilot not being part of the equation. I've always enjoyed those races and I think they will recover after this trajedy.

 

[Bringupthebird]

Todays WSJ echoed these sentiments. They're estimating a 10g uncontrolled pitch-up after the trim tab failed. That would knock out anyone. I would imagine that the seat would fail somewhere between 8-12g's as that would be more than enough for a pilot without a g suit. Also, strengthening a seat beyond that would add weight that they don't want to deal with.

Can anyone explain how a trim tab failure results in a 10G pull-up? How does the hinge fail before the bolt/bellcrank without taking the rear spar of the horiz stab with it. There's alot more area of the elevator trying to stay in one place than there is of the trim tab trying to move it.

 

[bubbers44]

My first thoughts too. Why couldn't he overpower the trim tab? Voodoo, an almost identical P51, had the same thing happen in 98 and pulled 10 G's with a much younger pilot and blacked him out too. He kept going up thousands of feet and as the speed fell off recovered.

 

[ackattacker]

Can anyone explain how a trim tab failure results in a 10G pull-up? How does the hinge fail before the bolt/bellcrank without taking the rear spar of the horiz stab with it. There's alot more area of the elevator trying to stay in one place than there is of the trim tab trying to move it.

I'll take a stab at it.

All conventionally rigged aircraft need more nose down trim the faster they go until you get into mach tuck regions. That's basic static stability, go faster the nose comes up. Remember that every stable aircraft has a basic speed it wants to fly which is determined by the position of the trim. If the trim tab is missing there's still a basic speed it wants to fly which is the same as a neutral trim position. Go faster than that speed it wants to pull up, go slower it wants to dive.

Unlimited warbirds are frequently modified with greater trim tab authority so they can go faster without running out of down trim. When they're going real fast the trim can be full down and applying considerable force to the elevator. Of course they may also play with the elevator incidence, maybe center of gravity to try to limit that, but fundamentally you need to make a compromise between high speed and low speed trim authority and basic stability.

The trim tab is servo tab applying force directly to the elevator not the bellcrank. When you're running at 490mph with the trim full down, the force on the elevator bellcrank is minimal. The force on the trim tab hinge is very large, it is forcing the elevator down and that's the thing opposing the natural tendency of the nose to come up. The elevator is fighting mightily to return to neutral, the trim tab is opposing it.

When that hinge fails due to the load, or the tab flutters and breaks off (which can happen in a fraction of a second), the elevator returns to neutral and suddenly the aircraft is nowhere near it's stable speed. It would require considerable down stick to hold the nose down. Maybe more strength than a man has. If you weren't right on top of it, the resultant pull up will knock you unconscious and the rest is history.

 

[HalinTexas]

The elevator is used to keep the nose up (more forward trim) as speed increases. Correct? While in a turn, more nose-up trim is used to hold the nose up? Correct? The question really is, What is that tab doing to the elevator while it's partially detached? Did it result in a control jam? What was the pilot doing with the trim while in the turn? Was he trimming? Remember, he was in a 70-80º bank, reference the other aircraft in the videos. Was the trim control jammed, and/or suddenly release, resulting in a pitch up. The other tab was still attached. Or, was the elevator jammed and the pilot using the trim, excessively, to try and trim the nose up while in the turn. I doubt we'll know until the investigators find that "magic BB." Lots of aerodynamics going on here that will make you dizzy.

As with most crashes, it isn't any ONE thing.

 

[HalinTexas]

I'll take a stab at it.

All conventionally rigged aircraft need more nose down trim the faster they go until you get into mach tuck regions. That's basic static stability, go faster the nose comes up. Remember that every stable aircraft has a basic speed it wants to fly which is determined by the position of the trim. If the trim tab is missing there's still a basic speed it wants to fly which is the same as a neutral trim position. Go faster than that speed it wants to pull up, go slower it wants to dive.

Unlimited warbirds are frequently modified with greater trim tab authority so they can go faster without running out of down trim. When they're going real fast the trim can be full down and applying considerable force to the elevator. Of course they may also play with the elevator incidence, maybe center of gravity to try to limit that, but fundamentally you need to make a compromise between high speed and low speed trim authority and basic stability.

The trim tab is servo tab applying force directly to the elevator not the bellcrank. When you're running at 490mph with the trim full down, the force on the elevator bellcrank is minimal. The force on the trim tab hinge is very large, it is forcing the elevator down and that's the thing opposing the natural tendency of the nose to come up. The elevator is fighting mightily to return to neutral, the trim tab is opposing it.

When that hinge fails due to the load, or the tab flutters and breaks off (which can happen in a fraction of a second), the elevator returns to neutral and suddenly the aircraft is nowhere near it's stable speed. It would require considerable down stick to hold the nose down. Maybe more strength than a man has. If you weren't right on top of it, the resultant pull up will knock you unconscious and the rest is history.

See, another theory. 5 minutes before mine. Entirely plausible, and probably more correct.

 

[Bringupthebird]

So Ack, you're saying that the entire airplane is riding on the bolt that holds the trim pushrod on? When I said bellcrank, I guess what I meant was the trim control horn, technically. Your explanation sounds plausible.

 

[Flopgut]

I've worked on and inspected my fair share of old airplanes. I'm not sure I'm 100% correct, but it might be time to park some of this WWII stuff? I know a good portion of the airplane has been replaced, but most of the mods are done to make it go faster. Racers might ought to be built from scratch and built just to race. The P51 was engineered to carrry weapons and fight.

 

[glasspilot1]

Ack, very well written explanation of how trim works. I think you hit the nail on the head; when that tab came off the nose came up so fast that he didn't have time to react before the G's took him out.

To HalinTexas, you trim for level flight, not for a turn. You're going way off the grid talking about turning and trimming.