Big Crash at Reno
CC makes a good point regarding the unlikelihood of wake turbulence being a potential factor in the left wing drop just prior to the pullup. With the wind blowing, there is plenty of ground features in that area of the course which could produce turbulence. In fact it's not unusual to see race planes bobble a bit while rounding the pylons whether from wake or other reasons.
I'm not sure about the trim tab failure being the cause of the rolling moment because the turn did not appear to tighten. Instead, the airplane appears to roll towards a wings level attitude before the increase in gee loading becomes apparent. I've thought from the start that the pitch up was due to the trim tab failure, but have no idea how much forward stick force would have been required to overcome the trim change resulting from the loss of the tab force. I suspect it's quite allot.
I've never flown a Mustang or any such high performance piston single and the highest IAS I've ever flown at is 360 KIAS, Vmo for a Westwind I. (nearly full nose down trim) Trying to imagine the trim suddenly going to neutral or less at that speed doesn't paint a pretty picture. Even the simulated trim runaway can be a handful at high speed if you don't push the trim disconnect pretty fast. Such a sudden change of required control force at near 500 mph in a Mustang must be much worse. I tend to doubt that Jimmy or anyone else would have had much chance of stopping the pitchup. Perhaps the final report will contain an analysis of the stick force change resulting from the trim tab failure. It's my feeling that any substantial instantaneous force change would likely be unrecoverable until the speed fell way off. Hannah was luckier in that his airplane climbed long enough for him to wake up.
As for all the talk about control surface stalls and high speed stalls, I just don't think that's a player here. The way I see it with the info we have right now, the tab broke, the airplane pitched up and put Jimmy to sleep with his head forward and down. With the Gee loaded on, the airplane slows down in the climb and P-factor or lack of corrective control input (pilot unconscious) rolls the plane into what amounts to a half barrel roll ending at the VIP boxes. It never looks stalled and the flightpath could easily be explained by the scenario above. As time goes on, newly revealed facts could certainly justify altering the theory to align with the new facts.
Like everyone else, I'll be interested to see a detailed accounting of all the factual data available to the NTSB team when they release it. As much as I respect their analysis of accidents, I like to do my own as well rather than just waiting to read the probable cause finding. As of today, no public docket info is yet available.
I'm not sure about the trim tab failure being the cause of the rolling moment because the turn did not appear to tighten. Instead, the airplane appears to roll towards a wings level attitude before the increase in gee loading becomes apparent. I've thought from the start that the pitch up was due to the trim tab failure, but have no idea how much forward stick force would have been required to overcome the trim change resulting from the loss of the tab force. I suspect it's quite allot.
I've never flown a Mustang or any such high performance piston single and the highest IAS I've ever flown at is 360 KIAS, Vmo for a Westwind I. (nearly full nose down trim) Trying to imagine the trim suddenly going to neutral or less at that speed doesn't paint a pretty picture. Even the simulated trim runaway can be a handful at high speed if you don't push the trim disconnect pretty fast. Such a sudden change of required control force at near 500 mph in a Mustang must be much worse. I tend to doubt that Jimmy or anyone else would have had much chance of stopping the pitchup. Perhaps the final report will contain an analysis of the stick force change resulting from the trim tab failure. It's my feeling that any substantial instantaneous force change would likely be unrecoverable until the speed fell way off. Hannah was luckier in that his airplane climbed long enough for him to wake up.
As for all the talk about control surface stalls and high speed stalls, I just don't think that's a player here. The way I see it with the info we have right now, the tab broke, the airplane pitched up and put Jimmy to sleep with his head forward and down. With the Gee loaded on, the airplane slows down in the climb and P-factor or lack of corrective control input (pilot unconscious) rolls the plane into what amounts to a half barrel roll ending at the VIP boxes. It never looks stalled and the flightpath could easily be explained by the scenario above. As time goes on, newly revealed facts could certainly justify altering the theory to align with the new facts.
Like everyone else, I'll be interested to see a detailed accounting of all the factual data available to the NTSB team when they release it. As much as I respect their analysis of accidents, I like to do my own as well rather than just waiting to read the probable cause finding. As of today, no public docket info is yet available.
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@Clipped Cub
Instead of pointing out what's wrong with my statements, you suggest google and then ask if I am a pilot.
Are you one? Really?
What is Leeward doing about his trim entering turns? Is he working it less Nose Down? Needing Pitch Up in the turn, he doesn't want trim Down, does he?
If he's leaving the tab up through the turn, using leverage at the stick to overcome it, for lack of time to neutral the Tab, his Nose up will greatly increase the Tab's exposure and angle to the slipstream. This greatly exaggerates the stress on the Tab. If it is at this point the Tab breaks, The Pitch Up will be disastrous, as per VooDoo.
Since the snap left was the first noticeable part of the Upset, It is reasonable to assume that this is where the Tab released its mounting.
I'm a humble Commercial Pilot, retired, without your degrees, but I venture to say I have a bit more courtesy than you.
What are your thoughts re: trim? Need a picture?
westhawk. The turn did tighten, and that may have been what caused the unwanted roll. In a steep turn, a Pitch up increases Roll into the turn. Left, in this case.
Instead of pointing out what's wrong with my statements, you suggest google and then ask if I am a pilot.
Are you one? Really?
What is Leeward doing about his trim entering turns? Is he working it less Nose Down? Needing Pitch Up in the turn, he doesn't want trim Down, does he?
If he's leaving the tab up through the turn, using leverage at the stick to overcome it, for lack of time to neutral the Tab, his Nose up will greatly increase the Tab's exposure and angle to the slipstream. This greatly exaggerates the stress on the Tab. If it is at this point the Tab breaks, The Pitch Up will be disastrous, as per VooDoo.
Since the snap left was the first noticeable part of the Upset, It is reasonable to assume that this is where the Tab released its mounting.
I'm a humble Commercial Pilot, retired, without your degrees, but I venture to say I have a bit more courtesy than you.
What are your thoughts re: trim? Need a picture?
westhawk. The turn did tighten, and that may have been what caused the unwanted roll. In a steep turn, a Pitch up increases Roll into the turn. Left, in this case.
Last edited by Lyman; 6th Oct 2011 at 05:31.
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Found this in another forum (and this was also not the origin):
From a friend who flies corporate jets for The Limited
Good News for the future of air racing.
Our new crew member, Matt Jackson, is not only a race pilot, aircraft
business owner and aircraft owner (he also takes care of Tom Cruises
P-51)but he is also the VP of the Unlimited Racing Class and head of
the Safety Committee.
We had a long talk about the Reno crash on the way to Mojave today.
Matt believes the cause of the crash was due to The Galloping Ghost
having a CG too close to the aft limit which resulted in pitch
instability. There are instructions on the P-51 regarding no combat
missions with the aft fuel tank full resulting in an aft CG problem.
Instructions specify to empty the aft fuel tank first in flight.
During qualifying Matt watched Galloping Ghost from inside the cockpit
of Furias and could not believe how much trouble Leeward was having in
keeping the Ghost in a stable pattern around the course.
Since Leeward lives in Florida and the Galloping Ghost was modified for
racing in Calif., when Leeward picked up the Ghost for the Reno races
at the last minute, a complete flight test program had not been done
based on available information.
There is a video of the entire last lap of the Ghost before the crash
which Matt showed me. As Leeward was coming around pylon #8 at about
480 mph after passing Rare Bear, he hit turbulence which pitched his
left wing down, Leeward corrected with hard right rudder and aileron.
Just as the aircraft was straightening out, he hit a second mountain of
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
Since the Ghost was racing at 480 mph with full right rudder and the
stick full right, this is where everything stayed when Leeward blacked
out.
Cockpit camera film that was salvaged from the wreck shows Leeward
slumped over to the right in the cockpit. As a result, the Ghost
climbed up and to the right, rolled over on her back and then headed
for the box seats. Most in the box seats never saw it coming because it
came in from behind them.
Matt has had long conversations with the NTSB who call the accident a
'fluke'. They are not going to recommend canceling future races. He has
also talked to the insurance companies covering the races for Reno and
they also say they are not going to cancel their coverage of future
races. Now we wait for the FAA to make a decision.
Good News for the future of air racing.
Our new crew member, Matt Jackson, is not only a race pilot, aircraft
business owner and aircraft owner (he also takes care of Tom Cruises
P-51)but he is also the VP of the Unlimited Racing Class and head of
the Safety Committee.
We had a long talk about the Reno crash on the way to Mojave today.
Matt believes the cause of the crash was due to The Galloping Ghost
having a CG too close to the aft limit which resulted in pitch
instability. There are instructions on the P-51 regarding no combat
missions with the aft fuel tank full resulting in an aft CG problem.
Instructions specify to empty the aft fuel tank first in flight.
During qualifying Matt watched Galloping Ghost from inside the cockpit
of Furias and could not believe how much trouble Leeward was having in
keeping the Ghost in a stable pattern around the course.
Since Leeward lives in Florida and the Galloping Ghost was modified for
racing in Calif., when Leeward picked up the Ghost for the Reno races
at the last minute, a complete flight test program had not been done
based on available information.
There is a video of the entire last lap of the Ghost before the crash
which Matt showed me. As Leeward was coming around pylon #8 at about
480 mph after passing Rare Bear, he hit turbulence which pitched his
left wing down, Leeward corrected with hard right rudder and aileron.
Just as the aircraft was straightening out, he hit a second mountain of
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
Since the Ghost was racing at 480 mph with full right rudder and the
stick full right, this is where everything stayed when Leeward blacked
out.
Cockpit camera film that was salvaged from the wreck shows Leeward
slumped over to the right in the cockpit. As a result, the Ghost
climbed up and to the right, rolled over on her back and then headed
for the box seats. Most in the box seats never saw it coming because it
came in from behind them.
Matt has had long conversations with the NTSB who call the accident a
'fluke'. They are not going to recommend canceling future races. He has
also talked to the insurance companies covering the races for Reno and
they also say they are not going to cancel their coverage of future
races. Now we wait for the FAA to make a decision.
Interesting what Jackson has to say. I would ask whether this aft CG induced pitch instability was noted during practice and qualifying. If so, wouldn't it have been addressed? I would tend to think so, but I wasn't there and am not privy to what went on inside Jimmy's team. Maybe Matt is...
I'd also be interested in knowing more about the sound of the trim tab breakage on tape. Which tape? Was the microphone in the airplane or somewhere on the ground? I ask only because I want to confirm that the sound noted is time synced with the visual and telemetry data.
As for the rumors about NTSB recommendations and insurance company willingness to issue policies for future races, that's reassuring even if only a rumor. I hope it's true and that the FAA won't come up with ridiculous rules. I also hope the race haters in Lemon Valley don't gain any extra traction because of the crash.
I'd also be interested in knowing more about the sound of the trim tab breakage on tape. Which tape? Was the microphone in the airplane or somewhere on the ground? I ask only because I want to confirm that the sound noted is time synced with the visual and telemetry data.
As for the rumors about NTSB recommendations and insurance company willingness to issue policies for future races, that's reassuring even if only a rumor. I hope it's true and that the FAA won't come up with ridiculous rules. I also hope the race haters in Lemon Valley don't gain any extra traction because of the crash.
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Couple of thoughts wrt trim specifically.
I doubt there would be a working of the trim in the turns. In my humble aero experience, we generally trim for a fairly high speed, and accept the pull elsewhere. Main reason for this is that the human arm works pretty well at holding and measuring a pull, much less accurately a push. I would imagine this holds for the racers too.
WRT the tab's AOA, it's angle to the free airstream may be increased, but I would question whether it would see much real AOA change - it is hung on the back of a big plate (elevator), which is conditioning a very large part of it's airflow. Further, at those sort of speeds, I doubt there's very much angular movement of the elevator (if you see what I mean). I'm also rather unsure about an increase in 'pull' increasing the roll. You need to increase the roll to maintain level flight/avoid a climb yes, but I don't believe it is causitive. There may be some aerodynamic effect that causes this in theory, however in my experience if I'm hanging out at big bank angles and whale on the stick, it doesn't effect roll one bit.
WRT a trim failure - I suspect the issue is less the overall stick force required for level flight, but the transient. Imagine you're flying along with a slight pull on the stick, and suddenly the trim force is removed. The stick smacks back at you; even assuming perfect conditions, it will take you some time to react and recover equilibrium. This presumably is behind the (much) earlier reported comments from someone saying that they told the race pilots not to use trim. Now assume you've been pulling 4g for a few seconds, and the event suddenly smacks you into the 10+G regime.. Not hard to imagine the world going black before you get it sorted.
I doubt there would be a working of the trim in the turns. In my humble aero experience, we generally trim for a fairly high speed, and accept the pull elsewhere. Main reason for this is that the human arm works pretty well at holding and measuring a pull, much less accurately a push. I would imagine this holds for the racers too.
WRT the tab's AOA, it's angle to the free airstream may be increased, but I would question whether it would see much real AOA change - it is hung on the back of a big plate (elevator), which is conditioning a very large part of it's airflow. Further, at those sort of speeds, I doubt there's very much angular movement of the elevator (if you see what I mean). I'm also rather unsure about an increase in 'pull' increasing the roll. You need to increase the roll to maintain level flight/avoid a climb yes, but I don't believe it is causitive. There may be some aerodynamic effect that causes this in theory, however in my experience if I'm hanging out at big bank angles and whale on the stick, it doesn't effect roll one bit.
WRT a trim failure - I suspect the issue is less the overall stick force required for level flight, but the transient. Imagine you're flying along with a slight pull on the stick, and suddenly the trim force is removed. The stick smacks back at you; even assuming perfect conditions, it will take you some time to react and recover equilibrium. This presumably is behind the (much) earlier reported comments from someone saying that they told the race pilots not to use trim. Now assume you've been pulling 4g for a few seconds, and the event suddenly smacks you into the 10+G regime.. Not hard to imagine the world going black before you get it sorted.
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I follow that. As seen, Leeward was pulling substantial g in the turn; acclimated to that, and pulling against trim to begin with, if it let go (the tab) the a/c would Pitch Up immediately, we saw VooDoo do that.
If the cg was too far aft, the a/c has a second instant problem, augmented climb. Additional Pitch UP. Since the a/c was wings vertical, the drop of the tail would cause wicked Yaw left. One g would express itself 'laterally' instead of 'vertically', relative to the airframe.
Turbulence? Causative? Hmmm. It may have been additive, but I doubt it was responsible. I'll go with it, if it helps politically. I think scrutiny of the Class will happen anyway, and we'll see 'improvements' in structures and policies? Regs?
Jackson himself let's the cat out anyway, describing the Ghost as 'unstable'. An entire lap of instability can't be down to wind. Is he some kind of "Spokesperson"? I'm just guessin' and readin'; sharper minds than mine will out.
If the cg was too far aft, the a/c has a second instant problem, augmented climb. Additional Pitch UP. Since the a/c was wings vertical, the drop of the tail would cause wicked Yaw left. One g would express itself 'laterally' instead of 'vertically', relative to the airframe.
Turbulence? Causative? Hmmm. It may have been additive, but I doubt it was responsible. I'll go with it, if it helps politically. I think scrutiny of the Class will happen anyway, and we'll see 'improvements' in structures and policies? Regs?
Jackson himself let's the cat out anyway, describing the Ghost as 'unstable'. An entire lap of instability can't be down to wind. Is he some kind of "Spokesperson"? I'm just guessin' and readin'; sharper minds than mine will out.
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I'm not sure about the trim tab failure being the cause of the rolling moment because the turn did not appear to tighten.
Just as the aircraft was straightening out, he hit a second mountain of
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
Since the Ghost was racing at 480 mph with full right rudder and the
stick full right, this is where everything stayed when Leeward blacked
out.
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
Since the Ghost was racing at 480 mph with full right rudder and the
stick full right, this is where everything stayed when Leeward blacked
out.
If I had to guess, Leeward felt the sudden pitch in the turn, knew what was coming from prior airplane tab scenarios, and went to wings level to give himself a chance. He was already clinced to counter the turn g, so when the g shot up, his current body configuration probably bought him another fraction of a second to react.
I would ask whether this aft CG induced pitch instability was noted during practice and qualifying.
I doubt there would be a working of the trim in the turns.
Instead of pointing out what's wrong with my statements, you suggest google and then ask if I am a pilot.
Are you one? Really?
but I venture to say I have a bit more courtesy than you.
What are your thoughts re: trim? Need a picture?
Somewhere in here, Penny talked about Rarebear trim. Ignore the stagnation point/ versus shock strength portion. That part's wrong.
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"Trim is untouched during the race."
That too is conjecture.
In the slomo run, I pay close attention to AoA as the roll left stops. From the constant perspective of the camera, we start to see more and more of the belly, out of sync with turn rate. This indicates a Nose UP trend, at least to me. There is a flash of up left aileron in the right reversal, suggesting the pilot was not in control, but that the ailerons were driven by airstream, not stick. I don't conclude that the pilot had time enough to recover from the left roll, nor that he had time to Rudder. If there is this flash of Nose UP, I think the pilot was out instantly. This Pitch caught him and his upper body left of the stick, and he was forcibly slumped into the left space, inputting an inadvertent right roll.
Some maths genius should calculate the g in the video supplied by the 'wrench'. He got 500 feet in less than ? seconds. I doubt 21g, but math is not me.
Thanks greatly for the RareBear vid. Takes stones to call Penny "wrong".
You are a hardass.....
It isn't only up to skull oxygenation, as you know. G can be a full on haymaker from a very big fist. Acceleration of the skull can lights out the brain in milliseconds. Plenty of O2.
That too is conjecture.
In the slomo run, I pay close attention to AoA as the roll left stops. From the constant perspective of the camera, we start to see more and more of the belly, out of sync with turn rate. This indicates a Nose UP trend, at least to me. There is a flash of up left aileron in the right reversal, suggesting the pilot was not in control, but that the ailerons were driven by airstream, not stick. I don't conclude that the pilot had time enough to recover from the left roll, nor that he had time to Rudder. If there is this flash of Nose UP, I think the pilot was out instantly. This Pitch caught him and his upper body left of the stick, and he was forcibly slumped into the left space, inputting an inadvertent right roll.
Some maths genius should calculate the g in the video supplied by the 'wrench'. He got 500 feet in less than ? seconds. I doubt 21g, but math is not me.
Thanks greatly for the RareBear vid. Takes stones to call Penny "wrong".
You are a hardass.....
It isn't only up to skull oxygenation, as you know. G can be a full on haymaker from a very big fist. Acceleration of the skull can lights out the brain in milliseconds. Plenty of O2.
Last edited by Lyman; 6th Oct 2011 at 14:41.
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It isn't only up to skull oxygenation, as you know. G can be a full on haymaker from a very big fist. Acceleration of the skull can lights out the brain in milliseconds. Plenty of O2.
We are not discussing direct impact to the skull. The Martin Baker back breaker used to give people an 18 g launch until the back injury statistics got out of line. Then they reduced the charge and added rocket motors to spread the impulse. But that 18 g kick did not put your lights out.
Lyman is well known from the AF447 threads, and his strengths appear to be in the legal direction rather than the aerodynamic ones, however he is not hesitant in trying to tell you his version of events, sometimes with fanciful additions.
I wouldn't absolutely discount his ideas, but instead examine them with a great deal of caution.
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The elevator trim is set for a specific pitch attitude and left like that until another specific pitch attitude is required.
It's one of the first lessons of flying.
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I have been all over the net regarding this iincident, and have seen a bunch of locked threads please don't let this happen here. This thread is amazing, thanks for all the insight. That said, Lyman any new thoughts on the aileron swap? Clipped, r u leaning towards the tt failing in the turn? Thanks again you guys.
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It was Matt Jackson who accused Leeward of flying with trim, not an opinion of mine.
At 74 yoa, this pilot had just had `~50 square feet of wing chopped off, along with half his ailerons. As far as we know, he had maybe an hour on the airframe.
In this heat, he was cooking, he's passed RareBear, and his trim tab was costing him maybe 2-3 knots. He won't fly trim?
He needs a note from his Mom?
Machinbird. With a selected ejection, you have your spine, erm, organized.
In a hot little P-51, drooling for the gold heat, Mr. Leeward's noggin was ready for 10 g's? It didn't bounce off the plex like the nine ball on a break?
You assume too much, and you question too little.
At 74 yoa, this pilot had just had `~50 square feet of wing chopped off, along with half his ailerons. As far as we know, he had maybe an hour on the airframe.
In this heat, he was cooking, he's passed RareBear, and his trim tab was costing him maybe 2-3 knots. He won't fly trim?
He needs a note from his Mom?
Machinbird. With a selected ejection, you have your spine, erm, organized.
In a hot little P-51, drooling for the gold heat, Mr. Leeward's noggin was ready for 10 g's? It didn't bounce off the plex like the nine ball on a break?
You assume too much, and you question too little.
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There's another reason not to touch the trim. The pilot can monitor aircraft status during the race. If the airplane exhibits any pitch changes, or stick force changes, that would be an indication to the pilot that the airplane configuration has changed.
Thanks for the heads up.
Lyman, you're requiring an emotional response and your posts, to me anyway, appear random, scattered with a lack of restraint, reduced self filtering, and now a lack of respect. Requires too much energy to find any worthy thought, and I don't have time to read your posts anymore so I'll be skipping over them. That also means I won't be responding to them. Nothing personal, there's room for all kinds of people in the world, I just choose who I communicate with whenever I can.
Lyman is well known from the AF447 threads, and his strengths appear to be in the legal direction rather than the aerodynamic ones, however he is not hesitant in trying to tell you his version of events, sometimes with fanciful additions.
I wouldn't absolutely discount his ideas, but instead examine them with a great deal of caution.
I wouldn't absolutely discount his ideas, but instead examine them with a great deal of caution.
Lyman, you're requiring an emotional response and your posts, to me anyway, appear random, scattered with a lack of restraint, reduced self filtering, and now a lack of respect. Requires too much energy to find any worthy thought, and I don't have time to read your posts anymore so I'll be skipping over them. That also means I won't be responding to them. Nothing personal, there's room for all kinds of people in the world, I just choose who I communicate with whenever I can.
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Just as the aircraft was straightening out, he hit a second mountain of
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
turbulence which caused the tail to 'dig in' resulting in a 10+ G climb
rendering Leeward unconscious instantly and resulted in the tail wheel
falling out. (broken tail wheel support structure was found on the
course). As the Ghost shot upward the LH elevator trim tab broke loose.
This can be heard on the tape, so the trim tab did not cause the
accident.
Looking at the Voodoo Chile picture of the tail after the event, the elevators are clearly pointing in different directions.
If you look at the elevator actuating bellcrank and a sample elevator, the most logical point of failure on Voodoo would be something like the 3 hole bracket on the end of the torque tube where it is riveted to the torque tube with what appears to be AN470 rivets
If the torque tube sheared outboard of that location, you would likely lose the entire elevator. since the center and outboard pivot points should fail sequentially if the inboard attachment is lost. The bracket collar would act to restrain the inboard end of the elevator torque tube if the rivets sheared.
Does anyone here actually know where the elevators separated/sheared on Voodoo?
Could shearing of torque tube rivets be an initiating event for what we saw happening on GG?
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Given all the obvious talent commentating on here, I am somewhat shocked that this little gem alledgely attributable to the NTSB has not drawn comment...
From my dictionary
Accident...
An unfortunate incident that happens unexpectedly and unintentionally
Fluke...
Unlikely chance occurrence
Not just semantics...I've never known an accident board to be the business of quantifying the part that lady luck has played in each and every accident (aviation or otherwise) since the dawn of time. I thought accident boards existed for the purpose of human enlightenment and such applications as the management of risk?
That statement could easily be construed as " sh1t happens...move on". Nothing wrong with that as a (somewhat unsophisticated) philosophy..but I hope the guy making that statement is not drawing a very large salary.
Matt has had long conversations with the NTSB who call the accident a
'fluke'.
'fluke'.
Accident...
An unfortunate incident that happens unexpectedly and unintentionally
Fluke...
Unlikely chance occurrence
Not just semantics...I've never known an accident board to be the business of quantifying the part that lady luck has played in each and every accident (aviation or otherwise) since the dawn of time. I thought accident boards existed for the purpose of human enlightenment and such applications as the management of risk?
That statement could easily be construed as " sh1t happens...move on". Nothing wrong with that as a (somewhat unsophisticated) philosophy..but I hope the guy making that statement is not drawing a very large salary.
Last edited by The Old Fat One; 7th Oct 2011 at 15:05.
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Does anyone here actually know where the elevators separated/sheared on Voodoo? 
Could shearing of torque tube rivets be an initiating event for what we saw happening on GG?
Found some g vs aging data, turns out we're pretty wimpy when we're young.
Relaxed +GZ tolerance in healthy men: effect of age.
[My paper] D H Hull, R A Wolthuis, K K Gillingham, J H Triebwasser
Fifty-three healthy US Air Force aircrewmen, 26-55 yr old, volunteered for a centrifuge study designed to determine the effect of age on relaxed +GZ tolerance. Each was subjected to G forces of gradual and rapid onset, with G tolerance determined by standardized contraction of peripheral visual fields. Of the subject characteristics studied, only age was positively correlated with rapid-onset G tolerance; both age and weight were positively correlated with gradual-onset G tolerance. A combination of age and weight gave a stronger positive correlation with G tolerance (rapid- and gradual-onset) than did either characteristic alone. No significant negative correlations were observed. We conclude that aging may offer some protection from G stress; there is no evidence that aging leads to a decrement in G tolerance.
[My paper] D H Hull, R A Wolthuis, K K Gillingham, J H Triebwasser
Fifty-three healthy US Air Force aircrewmen, 26-55 yr old, volunteered for a centrifuge study designed to determine the effect of age on relaxed +GZ tolerance. Each was subjected to G forces of gradual and rapid onset, with G tolerance determined by standardized contraction of peripheral visual fields. Of the subject characteristics studied, only age was positively correlated with rapid-onset G tolerance; both age and weight were positively correlated with gradual-onset G tolerance. A combination of age and weight gave a stronger positive correlation with G tolerance (rapid- and gradual-onset) than did either characteristic alone. No significant negative correlations were observed. We conclude that aging may offer some protection from G stress; there is no evidence that aging leads to a decrement in G tolerance.
G-induced loss of consciousness: case-control study of 78 G-Locs in the F-15, F-16, and A-10.
[My paper] Nereyda L Sevilla, John W Gardner
Department of Preventive Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA. [email protected]
INTRODUCTION: This study determined the trends of reported G-induced loss of consciousness (G-LOC) mishaps from 1980--1999, and determined potential risk factors in pilot characteristics; specifically, 30/60/ 90-h and sortie history, total flight hours, total hours in the aircraft, age, height, weight, and BMI. METHODS: Using aircraft malfunction mishaps to reflect a cross-section of USAF pilots, potential risk factors were determined using a case-control method; cases were all G-LOC mishaps and controls were aircraft malfunction mishaps. The data consisted of 2002 mishap pilots in the history of the F-16, F-15, F-15E, and A-10 from 1980-1999. RESULTS: During this time, G-LOCs represented only 2.5% of all mishaps. The mean engagement number for G-LOC mishaps was three at an average of 8 Gs. A poor anti-G straining maneuver was cited in 72% of the mishaps, fatigue and G-suit malfunction in 19%, low G-tolerance at 14%, and 37% were student pilots. Within pilot characteristics, only two factors were found to be statistically significant: the time in the aircraft and pilot age. In the F-16, there was a 3.5 times greater chance of experiencing a G-LOC mishap if the pilot had less than 600 h in the aircraft [3.5 (1.7-7.2, 95%CI)], and a 9.5 times greater chance in the F-15 [9.5 (2.2-41.9, 95%CI)]. There was a 4.5 times greater chance of experiencing a G-LOC mishap if under the age of 30 in the F-16 [4.5 (2.3-8.5, 95% CI)] and a 3 times greater chance in the F-15 [2.8 (1.2-6.8, 95% CI)]. DISCUSSION: Though it is difficult to predict who will experience G-LOC, emphasis on prevention must be concentrated in training and in pilots new to the aircraft.
INTRODUCTION: This study determined the trends of reported G-induced loss of consciousness (G-LOC) mishaps from 1980--1999, and determined potential risk factors in pilot characteristics; specifically, 30/60/ 90-h and sortie history, total flight hours, total hours in the aircraft, age, height, weight, and BMI. METHODS: Using aircraft malfunction mishaps to reflect a cross-section of USAF pilots, potential risk factors were determined using a case-control method; cases were all G-LOC mishaps and controls were aircraft malfunction mishaps. The data consisted of 2002 mishap pilots in the history of the F-16, F-15, F-15E, and A-10 from 1980-1999. RESULTS: During this time, G-LOCs represented only 2.5% of all mishaps. The mean engagement number for G-LOC mishaps was three at an average of 8 Gs. A poor anti-G straining maneuver was cited in 72% of the mishaps, fatigue and G-suit malfunction in 19%, low G-tolerance at 14%, and 37% were student pilots. Within pilot characteristics, only two factors were found to be statistically significant: the time in the aircraft and pilot age. In the F-16, there was a 3.5 times greater chance of experiencing a G-LOC mishap if the pilot had less than 600 h in the aircraft [3.5 (1.7-7.2, 95%CI)], and a 9.5 times greater chance in the F-15 [9.5 (2.2-41.9, 95%CI)]. There was a 4.5 times greater chance of experiencing a G-LOC mishap if under the age of 30 in the F-16 [4.5 (2.3-8.5, 95% CI)] and a 3 times greater chance in the F-15 [2.8 (1.2-6.8, 95% CI)]. DISCUSSION: Though it is difficult to predict who will experience G-LOC, emphasis on prevention must be concentrated in training and in pilots new to the aircraft.
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If the elevators had lost continuity along their hinge line, that should leave one operating, and one in trail. Since the assembly (gross) seems to have survived a potential fracture, there could have simply been a misalignment between the two, as shown in your pic of VooDoo. Had there been an actual separation at the bell crank center, the elevators would have shown some level of partition in the video, I think.
The design of this system shows an obvious plan for symmetrical Stress.
From a design standpoint, had there been a desire to allow differential forces on each elevator, the Torque Tube would have been one piece, not halves. The bell horn would have been halved, and surrounded the tube, in clam shell, or other, perhaps splines, allowing for erm, Torque.
Defeating this design (disabling trim on one side) appears to have some drawbacks in operation.
Machinbird's catch on VooDoo shows a greater up load on the left elevator, consistent with carrying chronic ND trim with only one elevator.
Nitpick. The picture of the elevator with tab on the bench is of the Ghost, not VooDoo. The image signature is "Scott Germain" proprietary to GG. So, we do not know the method of attachment of the tube to the retainer/cup on VooDoo. Likewise, the "Rivets" might be bolts; The join carries such stress, aluminum fasteners seem wrong.
Old Fat One. Absolutely, that word was not NTSB-ish. It was probably Jackson's. In American, "Fluke" means "Next to impossible" and "unrelated to responsibility". The only way to convey more innocence would be to call it an "Act of God".
The design of this system shows an obvious plan for symmetrical Stress.
From a design standpoint, had there been a desire to allow differential forces on each elevator, the Torque Tube would have been one piece, not halves. The bell horn would have been halved, and surrounded the tube, in clam shell, or other, perhaps splines, allowing for erm, Torque.
Defeating this design (disabling trim on one side) appears to have some drawbacks in operation.
Machinbird's catch on VooDoo shows a greater up load on the left elevator, consistent with carrying chronic ND trim with only one elevator.
Nitpick. The picture of the elevator with tab on the bench is of the Ghost, not VooDoo. The image signature is "Scott Germain" proprietary to GG. So, we do not know the method of attachment of the tube to the retainer/cup on VooDoo. Likewise, the "Rivets" might be bolts; The join carries such stress, aluminum fasteners seem wrong.
Old Fat One. Absolutely, that word was not NTSB-ish. It was probably Jackson's. In American, "Fluke" means "Next to impossible" and "unrelated to responsibility". The only way to convey more innocence would be to call it an "Act of God".
Last edited by Lyman; 7th Oct 2011 at 22:41.