Galloping Ghost crash - Theories

[Skinhead]

Telemetry downloaded from Galloping Ghost revealed an 11g pullup, fuel flow interrupted on the way up, and then the engine restarted when fuel flow resumed at the top of the arc. The aircraft was making 105 inches of MP (Manifold Pressure) on the way down.

 

A P-51 normally has two trim tabs - one on each elevator.  This one had one and other one was fixed in place.  He was warned about the forces being put on that one tab. It failed. He had at least a 10G load when the plane pitched up from the loss of the trim tab and he went "nighty night" and probably never woke up.

 

In 1989 this type of thing happened to another pilot but he lived to tell the story. When flying a P-51 at 450+mph you need to have full nose down trim to keep the plane level. The elevator trim tab broke off and the aircraft immediately went in to a 10G climb, confirmed by the G-meter. The pilot came to, from the sudden blackout and realized he had slipped through the shoulder harness and was looking at the floor of the airplane. He was able to reach the throttle and pull it back to slow down and was able to recover and land.

 

Photo one is the airplane taxiing, note the pilots head in the canopy.

 

Fast forward to 2011:

 

Photo two is typical oil canning as a result of the tremendous torque these engines put out at high power.

 

Photo three is a photo of GG upside down with a missing elevator trim tab.  Note all you see is the back of the pilots head indicating he is being forced down in the cockpit.

 

Photo four is a view of the left side nose down with the tail wheel extended and no view of the pilot.  The tail wheel is held up by hydraulics only with no mechanical uplock, thus indicating a high G-force causing it to extend.

 


Photos five and six are from the left side prior to impact, note no view of the pilot and the tailwheel extended.

 

Photo seven is the debris just after the crash. To the right of center above the crowd it appears to be the wing with the leading edge down.

[The Anvil]

Interesting. I don't think that oil canning is from engine torque though. The fuselage should be plenty strong enough to handle whatever that engine can put out. I once saw an IAI Astra with nearly the same condition and it's a jet.

However, an exceptionally aggressive maneuver (the same kind that can damage control surfaces) may very well be what caused it.

[Grumpy]

May well have been the horse power causing the oil canning, Stock Mustang is 1650 horse, Galloping ghost was 3800 horse power. here is a link to the specs on galloping ghost.

http://www2.leewardairranch.com/racing/galloping-ghost-specs

[BigAl]

Thanks I think that explains it.

THe story of him being a hero and missing the crowd was a bit over done.

As he was obviously passed out at the time in question.

I love the P-51 Mustang plane.

[Skinhead]

I just reposted it, I didn't write it, nor did I Snopes it to check it for accuracy.  I just thought it was interesting.  I'm also not an expert on P51's, nor an aeronautical engineer, (but I did stay at a Holiday in once).  

I assume that the skin of the P51 is rather thin aluminum, and it seems plausible to me that the torque of a 16 (or is it 12?) cylinder Rolls Royce Merlin engine combined with in flight stresses on the air frame could cause elastic deformation in the air craft skin resulting in the alleged "Oil Canning".  But then I could be wrong, I'll take the author at his word unless you can prove him wrong.

I did a quick google and found this:

http://www.ww2aircraft.net/forum/aviation/mustang-crashes-into-crowd-reno-30309-10.html

[Skinhead]

I mis-posted, I see from Grumpy's post that is was a packard V12 not the merlin engine.

[The Anvil]

May well have been the horse power causing the oil canning, Stock Mustang is 1650 horse, Galloping ghost was 3800 horse power. here is a link to the specs on galloping ghost.

http://www2.leewardairranch.com/racing/galloping-ghost-specs

Yeah but I still doubt that was the cause. It's usually sharp elevator input followed by a roll. If you load up the tail heavy enough and then twist the fuselage against that loaded tail surface it can cause that kind of condition. It's actually not all that uncommon on aerobatic aircraft, even fairly low powered ones.




Hijack: Interesting story about that Astra; the aircraft came in for an inspection and as the process was winding down one of the inspectors just happened to be looking down the fuselage in a certain way and saw the oil-canning. He called me over and asked me to have a look. I confirmed the oil canning then we looked at the aircraft from behind. You could actually see with the naked eye that the horizontal stabilizer was out of line with the wings. We brought lasers in and did some rigging checks and fount the aircraft had a pretty serious twist in it between the wing TE and the empennage. We took the engines off and de-skinned it to get a good look at the stringers and frame stations and determined that the plane was totaled. More to fix than it was worth. The funny part of the story is that the only pilot who had ever flown the aircraft (a former Israeli fighter pilot and IAI factory test pilot) wouldn't own up to anything. "I have no idea how the plane got twisted like a pretzel" was his distilled response to any and all questions.

[The Anvil]

I assume that the skin of the P51 is rather thin aluminum, and it seems plausible to me that the torque of a 16 (or is it 12?) cylinder Rolls Royce Merlin engine combined with in flight stresses on the air frame could cause elastic deformation in the air craft skin resulting in the alleged "Oil Canning".  But then I could be wrong, I'll take the author at his word unless you can prove him wrong.

You're right it is thin (as is all aircraft outer skin) but the skin is only a part of the structural strength component in a semi-monocoque fuselage. It's frames, bulkheads, stringers, longeron and skin all combining to make a strong assembly.

I won't say that the power of the engine could not have been a contributor. I suppose an aggressive enough roll opposite the direction of prop rotation combined with excessive tail loading could have all been contributing factors. It's just that I've seen this exact same phenomenon in aircraft that don't even have propellers so I'm skeptical of that claim that the engine had anything to do with it.

[Grumpy]

I assume that the skin of the P51 is rather thin aluminum, and it seems plausible to me that the torque of a 16 (or is it 12?) cylinder Rolls Royce Merlin engine combined with in flight stresses on the air frame could cause elastic deformation in the air craft skin resulting in the alleged "Oil Canning".  But then I could be wrong, I'll take the author at his word unless you can prove him wrong.

You're right it is thin (as is all aircraft outer skin) but the skin is only a part of the structural strength component in a semi-monocoque fuselage. It's frames, bulkheads, stringers, longeron and skin all combining to make a strong assembly.

I won't say that the power of the engine could not have been a contributor. I suppose an aggressive enough roll opposite the direction of prop rotation combined with excessive tail loading could have all been contributing factors. It's just that I've seen this exact same phenomenon in aircraft that don't even have propellers so I'm skeptical of that claim that the engine had anything to do with it.

I have flown in high performance aircraft, Was back seat in a p-40 trainer and had it demonstrated to me, engine torque roll, killed quite a few pilots years ago. 300 knots indicated, the pilot snapped the throttle full open, controls in neutral, I was on the stick. The aircraft violently snap rolled from the engine torque. very scary. He told me a lot of pilots died in that aircraft, due to a go around on landing, if you snapped the throttle open , the roll would cause a crash. I can see where countering the torque from 3600 hp could put some strain on the airframe.

[RP#62]

Lotsa airplanes oil can with no significant structural issues.  Next time you're close to a B-52 (any B-52) look down the fuselage, or for that matter just about any airplane that's done carrier ops.  In this case the trim tab appears to be the issue and the oil canning incidental.
-RP

[musclehead]

I know next to nothing about airplanes, I don't like to fly much. however the only thing I know about stunt planes is they are an unstable aircraft, it makes them very good for stunt work. unfortunately that also leads to crashes.

I heard an interview with a guy from Bakersfield that was approx 15' away from the point of impact and he didn't get a scratch. no fireball from the fuel, that would have made the injuries worse he saw lots of folks that had thier clothing splattered with the juice. as a retired EMT he went to work helping out with the injured.

[The Anvil]

Lotsa airplanes oil can with no significant structural issues.  Next time you're close to a B-52 (any B-52) look down the fuselage, or for that matter just about any airplane that's done carrier ops.  In this case the trim tab appears to be the issue and the oil canning incidental.
-RP

No kidding. Looks like Ruffles potato chips.

[Bob E.]

Wouldn't the twisting from the torque of the engine be resisted by the aileron trim tabs?  If so, I would expect the oil-canning to happen between the wings and the engine, rather than behind the wings.  I would agree with Anvil and guess this oil canning is from forces resulting from the aerobatic maneuvers.

[Westernbiker]

It was NOT an aerobatic airplane, it was a pillon race plane and it was modified for racing. High performance engine with mods, wings were trimed shorter than stock and many other things done for racing reasons.

[The Anvil]

It was NOT an aerobatic airplane, it was a pillon race plane and it was modified for racing. High performance engine with mods, wings were trimed shorter than stock and many other things done for racing reasons.

It's still capable of aerobatic maneuvers.

[YoungPUP]

I can identify a plane 2 out of 3 times, but i do know that if you push the limits of ANYTHING eventually it WILL push back.

[tank_post142]

my question: did it have a CT on the back?

[Grumpy]

It was NOT an aerobatic airplane, it was a pillon race plane and it was modified for racing. High performance engine with mods, wings were trimed shorter than stock and many other things done for racing reasons.

It's still capable of aerobatic maneuvers.

Not as aerobatic as it was when built, clipping 8 foot off the wings will lose a lot of ability. It was built for one use, speed.

[The Anvil]

Not as aerobatic as it was when built, clipping 8 foot off the wings will lose a lot of ability. It was built for one use, speed.

Reducing wing area does not (by default) reduce an aircraft's aerobatic ability and may actually increase maneuverability in some axes.

[The Anvil]

Wouldn't the twisting from the torque of the engine be resisted by the aileron trim tabs?  If so, I would expect the oil-canning to happen between the wings and the engine, rather than behind the wings.  I would agree with Anvil and guess this oil canning is from forces resulting from the aerobatic maneuvers.

On the P51 the engine and accessory section extend past the leading edge root. The firewall/bulkhead begins just after that exhaust shielding and that junction is super strong as is the cockpit area.



The spot between the wing TE and the empennage would be one of the weaker points of the aircraft as there's no intersecting structure like a wing beam or a firewall or a bulkhead, just longerons, frames, stringers and skin.

But you're right about where the force from engine torque would be concentrated and it's not there, it's on the firewall. But the force of any high speed, high load maneuvering (especially in the pitch and yaw axes) would be concentrated right about where you see that oil canning. But it's the combination of inputs like a hard pitch pull followed by a hard rudder kick that causes that kind of thing.

Think about it this way; you've got the tail control surfaces way back there controlling where the nose points way up front (ailerons aren't even strictly necessary for flight). All that force is concentrated in the middle and that's the most likely point of deformation.

[ricoman]

I would also think the shortened wingspan may have influenced the behavior.
Nearly 8" less than stock combined with all the engine modification has to contribute something to instability.

[Westernbiker]

It was NOT an aerobatic airplane, it was a pillon race plane and it was modified for racing. High performance engine with mods, wings were trimed shorter than stock and many other things done for racing reasons.

It's still capable of aerobatic maneuvers.

I didn't say it wasn't capable of aerobatics now did I?  I said this particular airplane was modified for racing and that's what the airplane was doing at the time! RACING! Quit trying to twist my words! 

[The Anvil]

It was NOT an aerobatic airplane, it was a pillon race plane and it was modified for racing. High performance engine with mods, wings were trimed shorter than stock and many other things done for racing reasons.

It's still capable of aerobatic maneuvers.

I didn't say it wasn't capable of aerobatics now did I?  I said this particular airplane was modified for racing and that's what the airplane was doing at the time! RACING! Quit trying to twist my words! 

Okay fine, but now you're splitting hairs. The point is that it wasn't the engine that caused that.

[Westernbiker]

NO! You're splitting hairs! And I never said it was the fault of the engine! Try understanding what was typed.

[The Anvil]

NO! You're splitting hairs! And I never said it was the fault of the engine! Try understanding what was typed.

I think you're being a bit vague. What is the point you're trying to make?

[Westernbiker]

Ok, let me clear it up for you. Someone refered to this aircraft as an aerobatic aircraft. I simply stated that it's intended purpose was for racing not aerobatics. Are ya with me still? Just about any aircraft can perform some sort of an aerobatic manuever even if it's just a simple wingover. I did not dispute the fact that this aircraft can still perform some aerobatic manuevers but it does not. It is strickly for racing and that's what all the mods. to the aircraft were intended for. Now, the point being, this is not an aerobatic aircraft PERIOD! If you were still able to walk up to the pilot and ask him 'Is this an aerobatic aircraft?' His answer would be 'No it's a racing aircraft. That is the point! Did that clear it up for you?

[The Anvil]

Ok, let me clear it up for you. Someone refered to this aircraft as an aerobatic aircraft. I simply stated that it's intended purpose was for racing not aerobatics. Are ya with me still? Just about any aircraft can perform some sort of an aerobatic manuever even if it's just a simple wingover. I did not dispute the fact that this aircraft can still perform some aerobatic manuevers but it does not. It is strickly for racing and that's what all the mods. to the aircraft were intended for. Now, the point being, this is not an aerobatic aircraft PERIOD! If you were still able to walk up to the pilot and ask him 'Is this an aerobatic aircraft?' His answer would be 'No it's a racing aircraft. That is the point! Did that clear it up for you?

First of all, I don't get the hostility but okay.

Anyway, air racing is not like drag racing. You don't simply go fast in a straight line. Even in pylon racing you are required to make hard rolls, rudder kicks and elevator inputs. That it wasn't doing Immelmanns and loops is not the point. Putting an aircraft into a high G bank turn is a basic aerobatic maneuver. Also, seeing as you are flying next to a bunch of other aircraft means that at any moment you may need to correct very hard. That imparts stresses that you see in aerobatics. So though it may not be an aerobatic specialist class aircraft it's most certainly aerobat capable and it puts those capabilities to use, even if only to a limited degree.

like I said; splitting hairs.

[Westernbiker]

I've been to more air races than you will ever dream of going to as my uncle was a racer himself and I stand by that the aircraft is NOT an aerobatic aircraft. Give it up and admit you made a faulty statement. No hostility here just tired of you thinking you know everything (After you research it) then post here. Give this one up, or can you even do that.

[The Anvil]

I've been to more air races than you will ever dream of going to as my uncle was a racer himself and I stand by that the aircraft is NOT an aerobatic aircraft.

Golf clap.

Give it up and admit you made a faulty statement. No hostility here just tired of you thinking you know everything (After you research it) then post here. Give this one up, or can you even do that.

Fine, I should have said "aerobat capable" instead of aerobatic. Are you happy now? (no, you're probably not).

[Westernbiker]

It's not a matter of being happy, it's a matter of 'If you made a mistake be a MAN about it and own up to it.' You will catch allot more ants with sugar than salt. I have nothing against you, you have made some very good points in other posts, it's just this one wasn't one of them. I expected you to own up to a misrepresented statement, as you expect everyone else to do on this board. So, I have no hard feelings even though you owned up to it with sarcasm, which is what I expected anyway. That kind of treatment towards people will eventually go away as you get older and more refined, at least I hope it does.

[ricoman]

Maybe we can stop the bickering (it is solving nothing).
Try this site for some interesting info about Mustangs
http://en.wikipedia.org/wiki/Cavalier_Mustang

In 1972 I had the very good fortune to catch a ride in one.
Without mods, as sold to the Bolivian Air Force it was a mindblowing experience for sure.

[Westernbiker]

Some good info but unfortunatly it has nothing to do with Anvil and I's discussion about a particular Mustang.

[The Anvil]

It's not a matter of being happy, it's a matter of 'If you made a mistake be a MAN about it and own up to it.' You will catch allot more ants with sugar than salt. I have nothing against you, you have made some very good points in other posts, it's just this one wasn't one of them. I expected you to own up to a misrepresented statement, as you expect everyone else to do on this board. So, I have no hard feelings even though you owned up to it with sarcasm, which is what I expected anyway. That kind of treatment towards people will eventually go away as you get older and more refined, at least I hope it does.

Honestly, I'd forgotten that I referred to it as an "aerobatic aircraft". I had to go back and re-read my posts. You're right, I should have called it "aerobatic capable" which is the proper technical term for an aircraft with aerobatic capabilities but is not necessarily designed intended for that purpose.

[Westernbiker]

No harm no foul. Have a great evening!

[The Anvil]

Some good info but unfortunatly it has nothing to do with Anvil and I's discussion about a particular Mustang.

Very interesting though that the airframe had that kind of longevity.

[ricoman]

Some good info but unfortunatly it has nothing to do with Anvil and I's discussion about a particular Mustang.

It absolutely does not have anything to do with your bickering.
I offered it as a good read.
You two go back to the  part where it makes sense arguing who is right or whatever the hell you were arguing about. I tired of it.

[Grumpy]

Some of the specifications really point out the differences, Galloping Ghost wing span 28' 11"
wing area  170 square feet.
Horse power 3800

Standard p51d as manufactured Wing span 37' 11"
Wing area 233.19 square feet
horse power 1649

Bottom line over 63 square foot smaller lift area
2151 more horse power

Ghost would be able to roll quicker, but a lot slower vertical response.

As the the oil canning, it you have ever flown a performance aircraft. I have, licensed pilot for 40 years, when making a severe turn As going left, when the wings approach vertical as in the race, the nose will start to go down, to keep level flight right rudder is applied to keep the nose up. It is the same procedure used to side slip an aircraft and it can impart a twisting motion to the rear fuselage. Normal flight for the design of an aircraft would not produce damage, but at the speed the plane was operating at there has to be loading of the structure.  As to a statement made earlier about ailerons being not necessary for flight, just try to turn with out them, rudder will just put the plane into a slide slip, coordinated turns, use aileron, rudder and elevator and power for a proper turn. Another aspect, is the prop wash from the engine, it leaves the prop in a spiral and as it travels down the aircraft will impart a side load to the rudder, any propeller aircraft, especially with a large prop require rudder input on the takeoff roll, the wash will tend to turn the airplane.

[Valkahuna]

Bill,

Thanks for bringing things back on course, and for the factual, technical explanation.

[The Anvil]

As to a statement made earlier about ailerons being not necessary for flight, just try to turn with out them, rudder will just put the plane into a slide slip, coordinated turns, use aileron, rudder and elevator and power for a proper turn.

Just to clarify on that, I said they're "not strictly necessary for flight". There are aircraft that do not have ailerons at all and in fact you can induce roll with the rudder, specially with a dihedral wing. Enough roll for lazy flight or emergency situations. With roll spoilers you don't need ailerons for anything which is why the Raytheon Premier doesn't even have them at all. Low speed maneuvering sucks though and you certainly couldn't fly a P51 the way it was intended to be flown without ailerons.

Another aspect, is the prop wash from the engine, it leaves the prop in a spiral and as it travels down the aircraft will impart a side load to the rudder, any propeller aircraft, especially with a large prop require rudder input on the takeoff roll, the wash will tend to turn the airplane.

True. That's also why the vertical stab is offset on prop driven planes, otherwise they won't fly straight without a bunch of rudder trim.

[Westernbiker]

Some good info but unfortunatly it has nothing to do with Anvil and I's discussion about a particular Mustang.

It absolutely does not have anything to do with your bickering.
I offered it as a good read.
You two go back to the  part where it makes sense arguing who is right or whatever the hell you were arguing about. I tired of it.

Call it what you will. And as far as you being tired of it, DON"T READ IT! Pretty simple fix huh.