Reno P-51 Mustang Lost Elevator Trim Tab

This photo, taken moments before the crash, shows that the P-51 had lost its left elevator trim tab. (I've circled the spot where the trim tab should be.) Without the trim tab, the aircraft may have been uncontrollable.

AP Photo/Grass Valley Union/Tim O'Brien

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(Original Photo by Tim O'Brien, Grass Valley Union (AP).)

Why did the aircraft lose its trim tab?  One possibility is "flutter," an aerodynamic phenomenon that can, once it starts, damage a control surface quite suddenly.  Here's a NASA video of flutter in action.

 

 

 

An aircraft is at risk of flutter when its airspeed pushes up against or exceeds its design limits.

 

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Comments (81) Read through and enter the discussion with the form at the end
Don Tireman - September 17, 2011 11:26 AM

Although one would think that the elevator would have far more authority than the trim tab, one of the factors to be considered is whether or not the elevator itself was subsequently jammed as a result of the trim tab separation, although the tab's central location suggests that it is a low probability...The critical factor undoubtedly will be the high speed, low altitude operating environment which didn't allow sufficient recovery time and space despite all efforts by the pilot to do so...

Bill - September 17, 2011 1:59 PM

It appears that not all of the trim tab is gone, only the part from where the control attaches to the inboard end. The rest appears to be there, but at an odd angle. On the P-51's I have seen, the trim tab is about 3 1/2 times as long as the part of the elevator trailing edge that is inboard of the trim tab. In this photo only about 2x is missing, and that corresponds to about where the control attachment point is. A racing plane is heavily modified, so this all may not apply...

lcs - September 17, 2011 7:25 PM

How could a P-51 exceed its design speed at level flight? The plane is capable of a nearly Mach 1 dive isn't it? Also, how do you know the trim tab is missing and not deployed downward? That would also cause the inversion.

zen - September 17, 2011 8:10 PM

Aren't both trim tabs linked? How could one be deployed downard while the other is level. If that's the case, wouldn't that induce a roll in the ipsilateral direction to the downward tab rather than a sharp climb?

zen - September 17, 2011 8:18 PM

The plane's design limits may have been Mach1 in a dive in 1943-45 with the original specs. But this plane is 65+ years old and heavily modified. Now, those modifications should take into account the constant high G turns of air racing, but this plane is out of the design envelope of the original fighter. It lacks the belly radiator, has shorter wings, tail stab, doesn't have the bubble canopy - and that's just the stuff we can see. Who knows how it has been lightened internally to improve performance.

Mike Danko - September 18, 2011 4:19 AM

@Ics - here's a link to a photo showing without doubt that the trim tab separated from the airframe => http://media.graytvinc.com/images/plane+enlarged.jpg
@zen - the Mustang "Voodoo" suffered a flutter-induced trim tab separation in 1998 at the Reno Air Races. The plane immediately shot into a climb. The 10G pull put the pilot to sleep. He came to just as the plane came over the top and was able to land safely. Very similar scenario but, of course, without the happy ending.

Robert - September 18, 2011 5:22 AM

Losing a trim tab by itself can not be the cause of this loss of control, ending in the crash that we saw. The tab is just an addition to the plane to ease flight, by balancing the flight controls.

However, the loss of the tab may be an indication of other damage.

For the moment, I still do not rule out the likeliness of the pilot losing conciousness.

JX - September 18, 2011 5:45 AM

I agree with Robert. An elevator trim tabs roll is not for control of the aircraft. It is the elevator which performs that. A trim tab's purpose is to reduce aerodynamic load on the control surface and thus reducing the effort required by the pilot. Also the trim tab came off after pulling the high G climb, there was already an issue with the aircraft before this happened.

Bob MacGregor - September 18, 2011 7:43 AM

As well as the departing/missing trim tab, the extended tail wheel appears anomalous in the pictures. Also there appears to be vapour streaming from the fuselage(coolant?). Any comments?

Mike Danko - September 18, 2011 7:52 AM

Bob -

The vapor trail could be indicative of some sort of problem, but then again fluids can stream whenever an aircraft isn't straight and level. The extended tail wheel, however, has me scratching my head. I'd be interested in others' thoughts on that.

Something else of note: you can't see the pilot's head in the cockpit. Possibly slumped over? Too many g's for the pilot to withstand?

The notion that the pilot tried to avoid the crowd in a nice thought, but it seems unlikely that he was awake at impact.

Louis Dobson - September 18, 2011 10:48 AM

The plane had boil off cooling. Hence the vapour and the missing radiator hump under the fuselage.

In my view a missing trim tab would cause exactly what happened here and in 1998, a sudden climb. This was a highly modified, very, very fast plane, and flutter would certainly be a danger.

I too noticed that the pilots head is not visible, and suspect the G forces rendered him unconscious as soon as the tab went - mercifully.

Thank you very much Mike Danko, a quick google search and all I wanted to know. Such a shame, reading the history of the plane.

Jeff - September 18, 2011 10:54 AM

According to reports, Jimmy Leeward radioed a single mayday just prior to the crash which would indicate a mechanical failure of some sort rather than him passing out.

Mike Danko - September 18, 2011 11:36 AM

Jeff -

Take a look at his post => http://tiny.cc/pilotreno. The report of the Voodoo pilot, plus the photos of Leeward's aircraft, suggest that Leeward was unconscious at impact.

JX - September 18, 2011 12:08 PM

Have a read of this, towards the bottom of the page www.avweb.com/news/reno2002/183113-1.html
What happened to this P-51 sounds exactly like what happened to Jimmy Leeward. Elevator failure following trim tab 'flutter'.

Mike Danko - September 18, 2011 12:16 PM

JX- Perhaps only difference is that Leeward didn't regain consciousness. Take a look at this post => http://tiny.cc/pilotreno

al - September 18, 2011 12:26 PM

>>>Although one would think that the elevator would have far more authority than the trim tab,

It does but a person like you (as opposed to superman) and I can't fight all the wind at those speeds going over the elevator.Like trying to lift a car. That what the trim tab does-allows you to move the elevator with not much effort

JX - September 18, 2011 1:29 PM

Yeah thats the one Mike. Looks a likely cause. I had a feeling he might have blacked out. He would have pulled a few g's in that climb and at that altitude there's no chance of recovery.

JX - September 18, 2011 1:33 PM

And yes Al, the elevator would definetly have authority over the trim tab. As per my previous posted link, a P-51 over 10 years ago had a trim tab 'flutter' which caused the elevator torque tube to fail.

lcs - September 18, 2011 3:11 PM

It is not clear that the trim tab departure was a cause or effect. Another thing I don't get. Why no fuel explosion on impact. I did not see any hint of a fireball. Was the plane out of gas?

dm - September 18, 2011 6:38 PM

This is just my amateur speculation, but it sounds like all the measures the owners took to reduce drag (shortening winds and tail length, removing cooling vents, etc.) may have caused such increased speeds that, when coupled with a stiff gust of wind, could have possibly caused the aircraft to pass the Vne speed, especially if they increased the engine's power, which they probably did (seeing as it's a racing plane and all...)

Bubba Edwards - September 19, 2011 6:01 AM

The tab in question is not a "trim tab." It is a "Control Tab." The function of the Control Tab is to "fly" the elevator. Without this tab the elevator will seek aerodynamic balance based on the speed of the aircraft and the relative pressures above and below the elevator. When this tab separated, the pilot was nothing more that a passenger. Where the aircraft hit was a matter of chance. The pitch up was a result of him instinctively rolling wigs level at the moment of failure followed by blacking out from instantaneous "G" onset. NTSB should be looking for the hinge point on the control tab. I believe that they will find an instantaneous stress fracture. All P-51's should be grounded until this critical flight area is inspected.

Nai24 is a graduate of the University of Southern California, School of Aircraft Accident Investigation and Safety.

John - September 19, 2011 6:02 AM

As you pilots know, if your trim tab is set wrong, the stick forces get excessive to the point where you can not move the elevator. Look at the broken tab, 2/3 is missing and the remaining 1/3 is deflected substantially in the down position which would move the elevator up, hence the loop to the crash. I believe the Gs were excessive and Jimmy was out cold for the crash (GLOC). Early P-51s had micarta (fibre) trim tabs, they tended to break at the hinges. Later planes had aluminum tabs and some early planes were retro-fitted. I have no idea which tab this plane had.

RWilliams - September 19, 2011 6:39 AM

LCS - the force of impact was so great that Any fire was extinguished. Like when they use dynamite to put out a fire at an oil well.

Mike Danko - September 19, 2011 6:53 AM

Bubba -

Well done. There has been quite a bit of confusion as to how a missing *trim* tab could have caused this accident sequence. I think you may have the answer.

Mike Danko

Bubba Edwards - September 19, 2011 7:37 AM

DC-9 and MD-80's are controlled in this same manner. Elevators on fast aircraft become unmanageable at high speeds, hence the development of the control tab to fly the primary flight control.

The news agencies need to get some more qualified talking heads before they spoil the jury pool. I'd be looking very closely at the maintenance logs. Even the most experienced pilot has very little, if any, training dealing with this type failure. In an ejection seat equipped aircraft it would be "Hand Grips- Raised" "Triggers- squeezed." No way is the aircraft recoverable.

JNev - September 19, 2011 9:18 AM

Still a lot of information yet to gather and consider, regardless of appearances.

It does appear in the photo that part of the trim tab remains - that portion outboard of the tab intermediate hinge. By the position (deflection) of the remaining portion of the tab it is implied that the two outboard tab hinges and trim horn (at intermediate hinge) may be intact; conversely, the remaining portion of the tab may simply be deflected by streaming from the deflected elevator at this point. This all further implies what we can observe: that the inboard portion of the tab (about 60% of the tab span) is missing - failed roughly at the intermediate hinge and inboard hinges - for whatever reason.

The remaining tab's deflection, at least on the LH elevator, is consistent with 'nose-up' elevator, as in fact we see the elevator - but as also said, this may simply be an effect of elevator deflection if the horn failed.

'Why' is still the question: did flutter suddenly occur and cause the tab to fail and shake other systems around, e.g. tail gear caused to extend, etc., or did a tab failure induce flutter... was flutter a cause or some other mechanical issue?

What we can now see and observe about the plane's behavior at the end of the flight do 'suggest' many 'obvious' things as 'cause' - but we only speculate by pinning too much credibility on those things right now. As others have noted, this was a highly-modified aircraft, so even my own observations above, consistent-with and based on comparison to original P-51 design data, may not even be reliable at all. In any case there are so many variables in these things - many more than I can think of and mention from the comfort of my chair. The investigation is in far better hands among those who go and study with experience and hard-won facts.

My thoughts and prayers are with those suffering and the survivors who lost loved ones and anxiously tend to their injured family and friends. My thoughts are also with the investigators - much hangs in the balance - understanding of what happened for those who lost so much, hard lessons to be applied for those who continue in Jimmy Leeward's big footsteps and the shape of the future for a great sport.

JX - September 19, 2011 10:35 AM

Bubba, I believe your term control tab is incorrect. An elevator control tab(servo tab) is designed to assist the elevator to move. I doubt an aircraft this size would need such an item, it is more for very large aircraft. For an aircraft circa 1940 a simple design of elevator and trim tab would have been standard design. Perhaps any P-51 guru's out there could confirm. And as per Mike Danko's previous post http://tiny.cc/pilotreno, history has shown that the P-51 has had a trim tab failure that resulted in very similar effects that happened to Jimmy Leeward. I expect what will come of this is a closer inspection of the P-51 elevator design, with respect to aircraft that are involved in high speed racing.

JNev - September 19, 2011 11:31 AM

The origingal P-51 design utilized a conventional 'trim tab', not a control-tab or servo-tab as in larger, heavier types (more typically transport types). This is born-out by a review of the original design: the elevator tab was 'screw driven' by cables driving a screw-type actuator with a push-rod at the tab horn.

'Galloping Ghost' could have had a different arrangement since it was highly modified, but I've found nothing indicating that so far.

The picture we have is consistent with the original tab arrangement: a tab spanning about 45% of full elevator span is observable. A portion of that tab appears to remain - that segment between where the intermediate (the 'middle' of 3 hinges at about 60% of tab span) and outboard hinges would be on an original P-51.

It would be interesting to find that servo tabs had been implemented in some fashion, but that adds weight and complexity that is not likely warranted: the original plane was well designed to easily approach the speeds the racers see, even if only in a dive. The big reason the racers modify so much is for higher sustained speeds around the course, not so much to gain a higher speed than the craft originally could attain in a dive, etc.

The 'conventional' flight control system seemed to serve the design well enough originally and it would be surprising to see a racer resort to a far more complex arrangement, like servo or control tabs in an already reasonably balanced system.

Regardless of whether the tab failed and caused issues or vice-versa, a damaged tab at high speeds is nearly always a big issue - be it trim, servo or otherwise.

Tony Johnstone - September 19, 2011 11:51 AM

Aircraft operate most efficiently in terms of speed with the center of gravity as far aft as possible. This is due to the reduced amount of downforce required from the horizontal stabilizer as the CG moves backward. Presumably this aircraft was operating at a far aft CG for that reason, this would require the elevator trim tab (yes, it is a "Trim" tab) to be deflected upwards to force the elevator down to maintain level flight. Once the tab separated the elevator would abruptly deflect upwards causing the pitchup.

Phantom II - September 19, 2011 12:00 PM

@ Bubba, there have been a number of P51s that have been flown with this tab missing. In aircraft that are equipped with a trim tab on the elevator, It is possible to fly the elevator with the trim wheel which renders it a control tab in your parlance. They have separate activation systems.
There are mechanisms that couple the control tab with elevator control mechanisms as is the case in the P51. This means that the pilot flies the elevator and pole loads are reduced by augmentation due to control tab deflections. The trim wheel will stagger the relationship. Stand outside and move the elevator up and down and observe the tab articulate. Get someone to turn the trim wheel and watch the tab move independently of the elevator. God only knows how this particular aircraft was modified but redundancy is crucial in this most critical of flight control components.

Jack Lynch - September 19, 2011 12:46 PM

I carry a single eng. 172 lic. with ifr rating. Please help me to understand why a trim tab, in my very limited knowledge of other high speed AC, It is quite hard to understand that it was just a trim tab

Jack Lynch

Chuck Webster - September 19, 2011 3:28 PM

Besides the "Voodoo Chile" incident in 1998 I think another P-51 went down in 2007 from the same thing. Yes, they test dove the original P-51s @ Mach 1 but let's not forget the word "Experimental". Changing so much of the overall aerodynamics of the original aircraft design as well as playing with the angle of incidence of that horizontal stabilizer has revealed a possible need for redesign in that area to accommodate said changes. Perhaps the shape, position or size of that tab may be in order.

joe litz - September 19, 2011 5:22 PM

I am still wondering what would have caused the tailwheel to extend. I do believe that these kind of exotic modifications to the wings, tail and control surfaces most certainly would rule out any real accurate speculation as to what really occurred in real time and why. after all it really is an experiment. All involved in these modifications know this. it is a calculated risk and these guys seem to feel it worth the risk. I can only guess that this airplane is a Mustang only by name and looks to a large extent. The dramatic acceleration to vertical would indeed seem natural when rolled quickly wings level, considering elevator input at the at that time. I can only guess that since whatever was encountered was so totally unexpected, a G induced loss of consciousness seems more likely than not to me...

joe litz - September 19, 2011 5:25 PM

I am still wondering what would have caused the tailwheel to extend. I do believe that these kind of exotic modifications to the wings, tail and control surfaces most certainly would rule out any real accurate speculation as to what really occurred in real time and why. after all it really is an experiment. All involved in these modifications know this. it is a calculated risk and these guys seem to feel it worth the risk. I can only guess that this airplane is a Mustang only by name and looks to a large extent. The dramatic acceleration to vertical would indeed seem natural when rolled quickly wings level, considering elevator input at the at that time. I can only guess that since whatever was encountered was so totally unexpected, a G induced loss of consciousness seems more likely than not to me...

lcs - September 19, 2011 5:36 PM

RWilliams - Dynamite extinguishes a fire because it rapidly consumes the available oxygen. I don't see the analogy here.

Bubba Edwards - September 19, 2011 6:00 PM

Many "Warbirds" operate under an experimental certification. Clipped wings are not a factor. I don't have access to a P-51D Dash 1 or -2. If someone does, please email me the flight control systems section. I will go to the air museum at Robins AFB and see if they have one on-hand. I suspect this bird had many STC's to get it ready to race in the unlimited class.

Mike C - September 19, 2011 6:14 PM

Tab was likely holding the elevator trailing edge down at the time of the failure. Natural float of the elevator was probably near neutral or slightly trailing edge up. With the tab gone, the elevator would float up. The pilot would have to hold it trailing edge down. He likely didn't have enough strength to do that at that speed. Aircraft pitched up and g started to build. To buy a few seconds before the aircraft over-g'd or he blacked out, pilot rolled the aircraft inverted. Once inverted, speed was still very high and he couldn't push the elevator trailing edge down enough to recover.

tim - September 19, 2011 8:14 PM

Did he just pass rarebear that thing screws the air in the other direction doesn't it. Could he have hit his air at the high speed stress loads and tore the tab off which caused other high stress loads on control assemblies that were built for 350 mph.

Yak52driver - September 19, 2011 8:37 PM

All of the publicly available evidence points to the loss of the trim tab as the primary cause. Why the tab seperated is a different issue, be it flutter, fatigue, damage or aerodynamic overload, only the investigation will tell. However, once it did seperate it was all over, it would have resulted in a rapid pull up, which would have "G locked" the pilot rendering him unable to recover the aircraft. As an aircraft increases its speed the lift forces increase (assuming fixed angle of incidence), requiring more forward stick to maintain level flight. To overcome these loads the pilot would feed in forward trim, at the speeds this racer was at there would be substantial forward trim required. Once the tab seperated the stick would have immediately, and totally unexpectedly jammed back, and without any warning it was probably pulled from the pilot's hands. Even if it wasn't, the sudden nose up pitching moment would have caused the pilot to black out given the size of the pitching moment, which can be seen by the fact that it was enough to cause the tailwheel to extend. You can also clearly see in a number of the still photos that the pilot appears to be incapacited. All the talk of servo tabs is irrelevant, the P51 doesn't have a servo tab (or anti servo tab), it has a basic trim tab, designed simply to reduce or eliminate stick loads at varying airspeeds and attitudes.

Mike Danko - September 19, 2011 8:43 PM

See http://tiny.cc/pilotreno for the still photos Yak52driver mentions.

Chuck Webster - September 20, 2011 7:01 AM

Besides the possibility of g forces pushing the tail wheel down we also have an incapacitated pilot slamming forward hitting various switches, one of which might have been for that. I think he blacked out as he tried to do a "wings level" putting right stick to it while recovering from the left turn and got pinned in that position Thank
God he didn't go another few hundred up or his corkscrew would have finished up about mid stands. Also, the outward speed of the dust blast from that 3'deep X 8'long concrete pulverization from the center of the crash may have been what dissipated the 1/2 tank of fuel left enough to out run any ignition source. Some quick prayers from folks helped too.

Chuck Webster - September 20, 2011 7:33 AM

I hope Experimental Aviation does not loose Reno over this. Remember Le Mans 1955? All motor racing was almost banned afterward. We would not have the safe cars of today if it had been. Even the air bag was originally invented by a few individuals. The Experimental Aviation community contributes majorly to the advancement of certified aviation with no corporate funding. As for flutter, here is some corporate testing. Even this test isn't 100% because there are so many different payload variations: http://www.youtube.com/watch?v=ImSuZjvkATw

Phantom II - September 20, 2011 7:35 AM

@Yak 52, We don't know what system is employed in this P51 yet. If it had a basic trim tab as you claim, how would the wing load increase in the event of a 'trim' tab failure? If anything, the wing would unload.
To be sure, there is a lot of thought that goes into the tail plane by the race engineers and it is kept pretty close to their vests. It is not your average military issue P51.
A trim tab would not be able to be activated rapidly and accurately unless it is a cable type handle as found on a Pitts which is not the case. The pilot workload would be excessive.
A coupled control tab would be the only solution to the constantly changing pilot demands. The horizontal stabilizer has probably got some negative incidence which could explain a pull back in the event of a tab failure. This incidence is not apparent to me on the ground, however.
The plane was already in a high pos. G turn and I can't imagine why the load would increase. I look forward to the investigation. I'm sure a lot of the closely guarded information will become public which would be of interest to the competitors.

Chuck Webster - September 20, 2011 10:28 AM

Whatever data exists from the other known failures of this part should be shared. Trade secrets are one thing but safety is a another. Making all sport flying safer ensures its' survival. Perhaps a voluntary AD type data base needs to be established for aerobatic and experimentals but viewable by all.

Greg H. - September 20, 2011 2:08 PM

Trim tab missing will provide asymmetric drag in a "loaded up" turn (right elevator having more total drag than left with missing control surface), having the effect of top rudder. This plane appeared to execute a displacement roll, what we used to do in air combat maneuvering with top rudder (increase drag/yaw away from turn), effecting a barrel roll away from original turn while still with control stick in belly.

mr.x - September 21, 2011 12:57 AM

Anyone know how many P51's are still in use?

Wallace Venable - September 21, 2011 10:51 AM

As an inactive pilot and retired engineering professor, I'm just thinking and speculating.

The plane was operating at very high speed. Assuming the trim tab was creating "nose down" forces, sudden loss of the tab could cause sudden increase of angle of attack. This could have two results:

(1) Stall initiation. (I have pondered P-51 stall characteristics ever since watching Bob Hoover's P-51 shows several times a couple of decades ago.) Clipped wings would probably create different stall characteristics than those of a stock P-51.

(2) Very rapid pitch up of the aircraft would generate gyroscopic roll motion.

The combination of a sudden, unexpected, stall and roll would be "difficult to control," regardless of a pilots age, health, experience, etc., and the low race altitude would give little recovery time.

In essence, the plane may have been entering something like an inverted "Lomcevak" ( - an uncontrolled tumbling maneuver.).

Phantom II - September 21, 2011 11:36 AM

@Greg: "Loaded up" turn..."displacement roll" .."top rudder"... What service uses terms like that? Not the airforce I know. A loaded wing either positive or negative with a deflected rudder will result in a snap roll or stall roll or whip stall and not a barrel roll. It is actually a dynamic entry spin and more of an aerobatic maneuver in light aircraft with a low loaded wing. Last US military planes that could do that were T6s or T28s and enormous pilot effort. This is definitely not a combat maneuver. Now any loaded wing with sufficient adverse yaw in piston engine aircraft could result in an inadvertent stall roll but it would be unlikely be caused by a missing or trailing trim tab. The resultant moment on the vertical axis shed by that small area must overcome the greater moment of the vertical fin and rudder on the same vertical axis. I don't think so. Scissor maneuvers which I think you are trying to describe a variant, are a thing of the past with the advent of high aspect ratio SAMs and AIMs. Vietnam was the last time they were used in combat because of really shit missiles. Even Jugs had 4 of their 8 machine guns offset for 20' aspect ratio attacks. Which service were you in?

Phantom II - September 21, 2011 2:01 PM

@ Wallace: I forgot about the disc precession of the prop, I assume that's what you meant. I'm a mechanical engineer. But, pray tell, what is the cause of the sudden pitch up? Any failure of the elevator or tailplane at high Gs would unload the wing. A sudden pitch down would result in the gyro precession inverting the plane to the left. Right?
Now an abrupt wing leveling maneuver in a high G turn would turn that lift vector 90' and the wing itself would cause a sudden pitch up and the large prop recession would load the disc at 90'off plane which would force the wing to continue the roll to the right. Right? So the first thing the pilot would or should do in case of an elevator failure is level the wing. Right? Maybe he should have unloaded the wing before he rolled out. Right? Even if he did unload the wing before rolling out to level, the lift vector at that speed would still cause a rapid pitch up, wouldn't it? Thanks professor in advance.

Bob - September 21, 2011 4:46 PM

Back in the 50's my Dad and I were flying from Montery, Ca to Freno, Ca in a Howard DG with a 450 hp P/W. On approach my Dad informed me the trim tab was stuck in cruise position and he would need some help on flaring out for landing. I'm here to tell you that it took the both of us to land that Howard. As most of you older pilots know, landing in a tail dragger requires a full stall landing. I wanted to add this story because it was a lesson I learned about trim tabs and the amont of load it has on the elevator. Can you imagine the trim malfuncting at 500 mph with seconds to recover?

Wallace Venable - September 22, 2011 10:21 AM

Sorry, my composition skills degrade when I try to compose in little boxes.

What I meant to say was:

A rapid change in pitch, combined with the large angular momentum of a big prop, will create a gyroscopic yaw moment. When an aircraft yaws during stall entry, one wing stalls before the other, and typically there is a "break" into a roll and spin initiation.

Of course, the result of tumbling out of an 80+° bank at 400+ knots and 1000 foot altitude is not likely the same as tumbling on a "up-line" at 100 knots and 3000 feet.

Phantom II - "I forgot about the disc precession of the prop, I assume that's what you meant. I'm a mechanical engineer."

I'm also an ME, but not an AE by training. As an "engineering mechanics guy," I just think of the result as a gyroscopic moment/ gyroscopic precession without worrying about what others may call it.

Phantom II - "But, pray tell, what is the cause of the sudden pitch up?"

The videos I have seen don't give me any clue as to pitch up or down. Either would create a gyroscopic precession, although in opposite directions. If the aircraft was still in the high-bank turn at the start of the accident, I would guess that he was using strong back stick. If the trim was down for high speed,* sudden loss of the tab would have meant that both stick position and loss of trim forces would tend to bring the elevator up. Given a shoulder harness and high G's I would expect that any pilot body motions would tend to increase back-pressure on the stick.

Phantom II - "Even if he did unload the wing before rolling out to level...."

My intuition, based on the video clips, is that given the time required to respond to a novel situation (maybe 1/2 to 1 second) and the total accident time-to-crash (maybe as little as 2 seconds, maybe as much as 5 seconds ??? ) is that the pilot was unable to make significant control adjustments. The potential of a high G blackout increases the possibility that there was no time to maneuver.

* As a student pilot I learned that "the elevator controls airspeed, the throttle controls rate-of-climb/descent."

Carl - September 22, 2011 2:56 PM

I didn't see Mr Leeward fly this year however, I was at Reno when Bob Hanna had his problem (tab issue). And, yes you can loose control of any high speed aircraft should the tab fail during flight. The tabs relieve the flight control loads required by pilot input. The faster the aircraft the more the wing wants to climb and the more forward stick pressure it takes to hold the plane level. The Hanna's episode was caused by the phenolic (plastic WWII) tab material. Most racers have gone to metal tabs anyway by now. With Leeward's plane having one tab disabled only loads the working tab even more to include torquing the elevator system.

Martin - September 22, 2011 4:59 PM

As being a modified aircraft the flight envelope is altered and only a totally independent study of the GG modifications can come up with an indication of the percentage of probable cause or influence of the partial tab separation. Studying the P-51 manual and standard handling characteristics the trim tab can affect flight performance but normally not significant enough to create an extreme imbalance. From the enhanced photo the separation appears be during the uncommanded roll? What I find interesting, without knowing the position of the sun, colour of the modified components, or enhancement software - is looking at length of the aircraft the rudder appears to be slightly to the right. I can also not properly see the position of the pilots head in relation to the instrument panel. Whether tab, tab actuator, flutter, pilot incapacitation or fatigue, prior photos of the position of the elevators, the list goes on I can only off condolences to the families, a quick recovery for the injured and outcome to learn from.

Martin - September 22, 2011 8:28 PM

As being a modified aircraft the flight envelope is altered and only a totally independent study of the GG modifications can come up with an indication of the percentage of probable cause or influence of the partial tab separation. Studying the P-51 manual and standard handling characteristics the trim tab can affect flight performance but normally not significant enough to create an extreme imbalance. From the enhanced photo the separation appears be during the uncommanded roll? What I find interesting, without knowing the position of the sun, colour of the modified components, or enhancement software - is looking at length of the aircraft the rudder appears to be slightly to the right. I can also not properly see the position of the pilots head in relation to the instrument panel. Whether tab, tab actuator, flutter, pilot incapacitation or fatigue, prior photos of the position of the elevators, the list goes on I can only off condolences to the families, a quick recovery for the injured , loss of a great pilot and outcome to learn from

Martin - September 22, 2011 8:29 PM

As being a modified aircraft the flight envelope is altered and only a totally independent study of the GG modifications can come up with an indication of the percentage of probable cause or influence of the partial tab separation. Studying the P-51 manual and standard handling characteristics the trim tab can affect flight performance but normally not significant enough to create an extreme imbalance. From the enhanced photo the separation appears be during the uncommanded roll? What I find interesting, without knowing the position of the sun, colour of the modified components, or enhancement software - is looking at length of the aircraft the rudder appears to be slightly to the right. I can also not properly see the position of the pilots head in relation to the instrument panel. Whether tab, tab actuator, flutter, pilot incapacitation or fatigue, prior photos of the position of the elevators, the list goes on I can only off condolences to the families, a quick recovery for the injured , loss of a great pilot and outcome to learn from

Phantom II - September 23, 2011 7:19 AM

Thanks Prof. Too bad there isn't a facility to edit our posts. @Carl: That's what I thought. It's the wing profile, stupid. Not you. You know what I mean?
I had a Pitts and you could pull it real hard at a 90'bank @ 130kts and if you leveled off abruptly, there would be no noticeable tendency to pitch up. The wings are almost symmetrical with a very poor glide ratio. I have a Baron 58 and it probably weighs about the same as those stripped down p51s. Any roll out from a steep bank at 160kts to level flight would also demonstrate no noticeable pitch up with a fairly efficient non laminar flow wing. An F4 at 90' bank at 450kts and a sudden roll out to level would have no pitch up tendency.It looses so much energy that you have to pull back anyway. It's the wing profile, stupid. Not you. That was the beginnings of critical profiles. Now the P51 profile was one of the first laminar wings and even though it is chopped off considerably, it would be able to produce huge amounts of lift at those speeds in an aircraft Those Red Bull air race aircraft make 11 to 15g spiked turns at up to 300mph after a dive. Abrupt roll outs don't seem to present any adverse pitch up challenge to the pilots. They have become specialized machines that probably have poor inverted flight capabilities compared to the aircraft they are derived from. Sure wish an aeronautical engineer would comment here.

Phantom II - September 23, 2011 11:30 AM

I didn't complete a sentence in my previous post:
'....at those speeds in an aircraft that was designed for a mass nearly 3X as much.'
I wonder what the new wing loading is compared to the old? It could be less. Probably needs less A of A than the original also.

Ric M - September 25, 2011 10:21 PM

This is one of the best forums so far-I was at the race. One question to be asked is the effect of wake turbulance caused by Leeward trying the pass the plane in front of him. He needed a top finish to advance-my observation is he pushed too hard and broke the aircraft.

Wallace Venable - September 26, 2011 1:53 PM

I'm sure he was "pushing," but I would guess that the trim tab was lost due to age, failed fasteners, fatigue, or something of the sort. The "pushing" contributed in that it meant he was right "on the edge" when the failure occurred, and that if it had failed a minute earlier or later, he might have recovered.

It is generally held that "really bad things happen due to a combination of factors." Not from a simple, single, cause.

Charlee - September 26, 2011 4:03 PM

http://vimeo.com/29519344

This video has the entire race. Leeward went into his final turn at an almost 90 degree bank, then rolled left more to put it past 90 degrees. There is then a huge positive pitch imput that created the forces that lowered the tail wheel (while still in the bank) and resulted in a tip stall that snapped the aircraft to the right. I feel it was the loads during this sequence that damaged the trim tab, which departed the elevator seconds later, and that the trim tab did not cause the accident. The amount of up elevator travel in the above picture is still a mystery to me.

Mike Danko - September 26, 2011 5:37 PM

Charlee-

Interesting video.

The vice president of the Unlimited Racing Class, Matt Jackson, told the Reno Gazette-Journal that the reason the trim tab separated was because Leeward used it to control the aircraft's pitch coming off the last pylon. Jackson says that trim shouldn't be touched once the aircraft is at race speeds.

Charlee - September 26, 2011 6:57 PM

I feel that the lack of a fire on impact was caused by The Galloping Ghost's boil-off cooling system, which submerged the radiators in coolant. The aircraft carried as much coolant as it did fuel and they may have mixed together at impact to prevent ignition.
During the period that the National Guard flew the P-51, they permanently locked down the tail wheel due to weakness in its design. Something related to this fault probably caused Leeward's tailwheel to extend under the extreme G-forces.
Disabling the right elevator trim tab makes no sense to me. The left one would still have to produce the same amount of triming force that the two combined would, probably producing the same amount of drag. I don't see where this mod could increase speed. If it was done to save weight, common sense was thrown out the window.
Leeward may have hit turbulence from Voodoo that caused the additional roll to the left that put the aircraft past a vertical bank in the last turn. The amount of pitch change in the next split second is frightening considering the speed the aircraft was flying at. It's amazing the whole aircraft didn't come apart at that moment.

Charlee - September 27, 2011 9:59 AM

The Making of The Galloping Ghost

http://www.warbirdaeropress.com/NewGallery/GG2009-1/index.html

http://www.warbirdaeropress.com/NewGallery/GG2009-2/index.html

The first link has the construction pictures. Photos 86, 92 & 150 show the elevator trim tab.
From the photos of the cockpit, I can't tell where the control is for the elevator trim. Does anyone know where it is?

PrivatePilot2 - September 27, 2011 1:41 PM

After studying the video above, I believe that the plane got into an unwanted attitude, he tried to correct putting undue stress on tail section which caused trim tab to fail putting the plane into a steep high G climb which rendered the pilot unconsious. From then on, just simple laws of phyics took over.

PrivatePilot2 - September 27, 2011 1:57 PM

Check this link and it clearly shows plane still in an arc trying to go up. I still believe the pilot was out at this point and the miss trim tab is what makes the plane still want to go up making the arc in the decent and final impact.

http://www.youtube.com/watch?v=ypyhTdzKD9E

Phantom II - September 28, 2011 7:27 AM

I wonder if he steered his craft upwards intentionally to gain altitude because of some problem. Some say engine. He already was in a high G turn and probably exceeded his G tolerance duration in this maneuver and blacked out where the laws of physics unfolded as they should. Can't see how a failed trim tab can increase wing loading. Dying like this is better than surrendering ungracefully to the counseling of the years. Fly on brother. You will be getting your next set of wings pretty soon and 10 of your fans will be fly formation with you.

PrivatePilot2 - September 28, 2011 10:48 AM

I still think it was a problem with the airplane based on my experience with flying. As you can see in the video, the trim tab came off when the airplane went inverted but I think there was trouble before that. If the plane had to be trimmed heavy to maintain a nose level attitude, then at the speed he was going, if the trim broke or came loose in some way, it would have pitched the plane up violently and that's what looks like happened.
As you stated Phantom II, he was already in a high G turn plus the added G's of going up. I'm sure he was out and had no control of the airplane. With the trim tab gone, the airplane wanted a nose up attitude which explains, combined with torque, looks like exactly what happened. I wonder if the tab that came off before impact has been found?
The NTSB is very thorough in their investigations and I'm sure they will find the cause.

Charlee - September 28, 2011 11:02 AM

http://www.stclairphoto-imaging.com/360/P51-Mustang/P51_swf.html

This link gives exact details of a stock P-51 cockpit. Compare it to photo 110 of the cockpit in the GG construction sequence.
Check out the photo from post 16 from this link:
http://www.aafo.com/hangartalk/showthread.php?t=9271&page=2
This was taken during a qualifying run while the aircraft was level and not under extreme loads. There are major ripples in the fuselage side, which makes me question the changes that were made the basic P-51 structure. The smooth finish they worked for on the aluminum skins to reduce drag are all for not if deformations like this occur.
If Matt Jackson is right and Leeward was using the trim tab as a secondary control, Jimmy went into those final turns with his right hand on the stick and his left on the elevator trim tab control. The possible turbulence he hit that caused the aircraft to overroll may have inadvertantly caused him to apply excessive up trim, which resulted in the 90 degree snap roll to the right and the subsequent structural failure of the trim tab from the overload. If it wasn't turbulence that started the sequence, a medical problem may have caused Leeward to jerk the controls. A third possibility, which most of us don't want to believe, is that Leeward just screwed-up when he tried to tighten the turn.

Phantom II - September 28, 2011 1:54 PM

@ PP2. Check this vid. http://www.youtube.com/watch?v=EPDPQnsbmu4&feature=related
It beats me why a sudden pitch up is caused by a jettisoned tab. The ghost is already in a pretty high G turn so precession and asymmetric disc loading was accounted for by Leeward. In the near vertical climb the speed was sufficient to preclude torque effect and the craft showed no signs of looping. From what I can determine with the limited info I have received, I say Leeward intentionally broke course to convert energy because of a problem be it engine or elevator. In so doing, he lost conscientiousness. The wrinkles on the empennage sp.? is bothersome.

Charlee - September 28, 2011 2:48 PM

With the aircraft configured for down trim, the trim tab is pushing the elevator down. With the aircraft in a tight turn, the pilot is pulling back on the stick very hard. If the trim tab were to suddenly stop providing the downward force, it would be virtually impossible for the pilot not to instantly be pulling back even more on the stick. Even a split second of this increased elevator imput can be disastrous.
Telemetry shows the engine was not a factor in the accident.

Charlee - October 1, 2011 12:08 PM

One "fact" that has been repeated many times is that at the impact point there was an area 3 feet deep annd 8 feet long. This is a strange description in that it doesn't mention a width. I think this is the result of a misinterpretation. If you look at the NPR video of the aftermath, injured spectators are being taken over the impact point, which appears to be about 3 feet wide and 8 feet long, with a large puddle of what appears to be coolant next to it. The gouge doesn't seem to be more the 3 inches deep, which is amazing considering the speed that the aircraft hit the tarmac.
Another scenerio to consider for the crash is that Leeward, after the high Gs while in the vertical bank, was pinned down in the forward part of the cockpit but still conscious. From this position the only control he may have been able to operate was the elevator trim tab. The natural instinct for humans, when they are in trouble in an aircraft, is to pull up elevator. Leeward was an expert pilot, however, and he may have put in full up elevator trim as the best option to keep the aircraft away from the crowd. Being pinned down, he probably had no idea what the attitude and position of the aircraft was. The photos we have seen show no evidence of flutter in the trim tab before it separated from the elevator. The full up trim, at the speed the aircraft was at, could have overloaded the tab's structure, causing 2/3 of it to breakaway. Photos show the remaining 1/3 to still be in the full up trim position, which could explain why the elevator is at almost its full up position (for the speed it was at) up to the impact. Leeward, or the weight of his body, was in no positon to be pulling back on the stick.
Since I was not at Reno this year some may say the following is easy for me to say, but this may be a "Its A Wonderful Life" moment for aviation enthusiasts. If the race organizers have to give back all the money that spectators paid, like Jimmy Stewart's Savings and Loan, it may be the straw that breaks air racing's back. Maybe someone needs to set up a fund that aviation minded people can contribute $50 or $100 to keep air racing alive.

tom - October 7, 2011 8:50 PM

I'm a ME too but an aviation novice.

Just thinking about the pitch up due to trim tab loss, what would happen if the stabilizer was angled so that with no elevator input, the plane flied level at some higher speed, say 350 mph?

As far as racing mods, there is one tradeoff I can see: stabilizer angle -v- rudder/tab input. You can trade one for the other at a given speed. So what produces least drag?

The Connie tried to generate lift with the fuselage which was a drag disaster. Could it be that they are trying to generate most of the lift in the rudder itself and not the stabilizer (via angle) because the stabilizer is like the Connie fuselage, i.e., the "big" part?

____________

Thinking about the stabilizer and wing again... If the design is to balance CG with zero control input at a low speed, say 150 mph, what happens when you increase speed?

Lift on both surfaces goes up big time, so the plane starts to climb. So to go level, the elevator has to rotate down to lift the tail and reduce AOA on the wing.

At high speed there would be a lot of this, so the trim tab would be angled up to push the elevator down for level flight.

If the trim fails, the elevator would move upward, increasing AOA of the wing and the plane pitches up.

So to mitigate the pitch up, the stabilizer angle should be balanced with the wing at a higher speed to reduce the needed input in the elevator at high speed.

Of course if they are trying to "fly off the elevator," this would make the plane very dangerous if the trim tab was lost.

Its late and brain turning into pudding....

Fascinating thread!

Regards,
Tom

Charlee - October 26, 2011 4:09 PM

From AVweb:

Video memory cards and equipment recovered from the wreckage of Jimmy Leeward's P-51 at the National Championship Air Races last month in Reno were too badly damaged to be of any help in the investigation of the crash, the NTSB said Friday. However, a card retrieved from flight data equipment and telemetry received by the ground crew of the Galloping Ghost are still being examined as investigators piece together the five seconds between a normal home-stretch pylon turn and a high-speed dive that ended with a horrific crash that killed 11, including Leeward, and injured scores of others. "NTSB investigators continue to review the dozens of videos and hundreds of photographs provided to them by spectators at the air race," the board said in a news release.

Investigators continue to examine the left elevator trim tab to determine how its departure from the aircraft affected the chain of events. The role of the trim tab has been the subject of much debate on various blogs and forums and some have concluded its loss was a consequence and not a cause. It will, of course, be months and perhaps years before the NTSB reaches its final conclusions on the tragedy.

Phantom II - November 2, 2011 7:38 AM

Bobby Graham says...About a month ago.

"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 aileron 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.

Ironically, Matt bought box seats tickets for his good friends who stayed with him for a few days before the races. They were the husband and wife
who were killed.
--
Thank You for choosing
Bobby's Aero Services
1641 Sessums Dr .
Redlands , Ca 92374
(909)534-7675

In summation, Somehow the center tank had fuel in it which caused a aft CG out of envelope. Hard to believe. The capacity was 91 gallons restricted to 65 gallons and level flight.
The horizontal stabilizer stalled in the #8 turn and caused a pitch up which incapacitated the pilot. The left wing tank is used for takeoff only. The ferry pilot did not use the center tank and was overlooked before the race. It does explain a lot.

Mike Danko - November 4, 2011 7:28 AM

Phantom II-

Interesting analysis. Matt Jackson keeps saying that he knows exactly what happened but it has changed three times. Pilot error. Turbulence. Now fuel imbalance.

I am certain that the NTSB did not tell Jackson the accident was a "fluke" or tell him what safety recommendations they would issue.

Also, contrary to the story, the NSTB has said no video was recovered from the aircraft.

PrivatePilot2 - November 15, 2011 12:59 PM

Phantom II, don't mean to disagree, but I still think the broken trim tab did cause the crash. I think it broke when he corrected for the turbulence or whatever caused the left wing to drop. I don't believe the turbulence made the tail dig in, I think the tab was already broken when plane went into steep climb. Don't see how turbulence can make a plane pitch up that violently. JMHO

Charlee - December 1, 2011 3:15 PM

The following is from an e-mail from Alby Redick of Aviation Classics. Bob Button, the owner of Voodoo, is selling the aircraft and will not race again. He states this decision was made before September's race.

News from the Air Race folks is this:
FAA has no issue with the Races continuing.
NTSB has no issue with the Races continuing
RARA is asking for concessions from Race Teams and Fans to voluntarily forego prize money, and or ticket refunds so they can afford to put on the Race next year. Scuttlebutt says that they currently have $2Mil in the Bank, $3Mil in Bills due and Payable from 2011, and they need about $800K in the Bank to get the next years Air Races going…
Insurance Underwriters have agreed to write a new Policy
There is only scuttlebutt so far about taking a hard look at Pylon 8 relocation or negation (is that a word?), just talk at this point…
A number of Air Race Trustees have been served, so there is great concern that they are potentially personally liable, however the laws governing a 501-C3 Charity should hold up to insulate them.
They have capped the impact site and fenced it in, with a 24 hour guard at the site.
Ramp-Rumor has it that Bob Button is pulling out.

kim fawkes - April 2, 2012 11:28 PM

Re this crash at Reno. I have been investigating the crash of a WW2 Bristol Beaufort here in Australia - it crashed, as the report said, due to faulty locking of the fork end/actuator. Beauforts had the conventional trim tab/elevator combination with the fork end/actuator coupling secured by a lock nut and washer. Due to vibration and normal aerodynamic loading the nut rotated causing the washer to loosen and the actuator to disconnect from the fork end. As the fork end was connected to the control rod and trim tab the pilot suddenly found himself with trim control. Could this have contributed to the crash at Reno or was there some other reason for why the pilot had no trim control apart from flutter?

Your answers are greatly appreciated, cheers Kim

stewart munson - August 12, 2012 7:32 PM

Student Pilot: Please correct me if my premise is incorrect:

To compensate for an aircrafts in flight weight distribution or changes in dinamic pressure at various speeds trim is used to affect the control surfaces of the Elevator. When more positive angle of attack is desired - trim wheel is rolled backward, this deploys the trim tab down - it pushes the trailing edge of the elevator up - which tends to cause the aircraft to climb, or correct for a 'nose down' attitude.

In this case 2/3rds of the Left Trim Tab have broken away.

Does this picture indicate the remaining trim tab is in a down position, and elevator in an up position?

Could the effect of the inboard third of a Left Trim Tab have caused enough differential pressure to have also rolled the Mustang at MaxV?

All this took place in a few seconds; maybe six. Do gravitational forces cause instantaneous unconsciousness. Or are tunnel vision and eventual black out progressive?

PrivatePilot2 - September 18, 2012 11:01 AM

Look a the final findings of the NTSB for cause of accident, I rest my case!

Mike Danko - September 18, 2012 11:06 AM

@PrivatePilot2-

Yep. More on the final report here

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