#207

With asymmetric elevators (by aspect), and at 450mph, I am going to say the tail section rotated (twisted) counter/clockwise as seen from aft. This would cause the additive roll left of the airframe. This explains the additive left roll that made vertical the wings as explained elsewhere caused by W/T. The buckles show this torsional aspect in concert with a Yaw and "drop" of the tail, meaning that the more emphatic elevator was the right one, and if it imparted a down force, it meant the tabs were "up", at the time the left tab was lost. this is consistent with carrying a Nose Down bias in the circuit.

That area of the airframe is hardly what one could call "stressed skin" so the damage is not particularly surprising, as it results from a structural failure in a design consideration that needn't have been addressed.

A secondary analysis might include the buckling resulted from a massive Nose Up input. With the elevators trending up, the tail would would endure a great download, a longitudinal collapse downward could have produced the 'extra' skin necessary to produce the wrinkling.

A combination of both mechanical issues is also possible.

Reno Air Race Relief Fund
 

I came across this on aafo.com. Seems like a kind gesture to help the victims through a very difficult time.

Family Assistance Fund

http://www.thinkkindness.org/files/AirRace_FAF.pdf

Just found this, amazing photos, what a work of art
WarbirdAeroPress.com

Zulu Alpha

I believe that "wrinkling" image was not captured at the time of the accident but previous to the accident..

And thanks to Tredigraph below, I found the article that quoted Matt Jackson, President of the Unlimited class at Reno:

Jackson said the accident was the result of pilot error, not shoddy aircraft designs or the failure of the race organizers to ensure safe aircraft participate in the races.

“It was the mistake of one individual in making a critical decision — a decision that didn’t work out,” Jackson said. “It wasn’t deliberate. It was an accident — just like the accidents that happen every day out on the highway.”

According to Jackson, Jimmy Leeward, pilot of the ill-fated Galloping Ghost, made the mistake of using his “elevator trim tab” to control his plane during the Unlimited race on Friday, and the trim tab broke off, causing the plane to shoot into the air.

Jackson said the crash was an accident — not the result of sloppy designs or the lack of safety oversight on the aircraft.

Essentially, with the crash being an accident, it means the spectators might have an expectation of injury, as the tickets warn.

Jackson said the plane was safe if it was flown properly. He said Leeward made the mistake of using his trim tab on his tail to control his pitch, and the force of the speed was too much for that small piece of equipment, and it snapped off with catastrophic results.

“I know exactly what happened,” Jackson said, “and when the National Transportation Safety Board comes back with its report on the cause, they will say the same thing I’m saying.”

According to Jackson, Leeward’s elevator trim tab broke off when Leeward rounded turns No. 7 and 8.

“I always tell the pilots that we don’t touch the trim tabs on any of the fast airplanes,” Jackson said. “Apparently he was using the trim tab. It snapped off. That’s the pop we heard.”

When the trim tab broke, the Galloping Ghost shot into the air.

The G-force of about 9 caused Leeward to black out, and his body slumped forward, hitting the control stick and causing the plane to turn to the right and then down.

Photos of the plane support this, Jackson said. The back landing gear is down in photos of the plane just before it crashed. The landing gear is designed to deploy at 9 Gs, Jackson said.

In addition, Jackson said, Leeward was not visible in the cockpit of any of the photographs of the airplane’s final moments.

When racers fly, they set their shoulder harnesses to allow them to move around in the cockpit so that they can look over their shoulders for the other planes in the race. That would explain how Leeward disappeared from the cockpit, he said.

“The pilot blacked out or was dead in the airplane,” Jackson said. “His body came forward and he was pushed against the stick.”

“It’s going to come out that the trim tab failed,” Jackson said. “The plane that crashed was a very precise aircraft. Nothing had been short-cutted.”

It was an accident — not a design flaw, Jackson said."


The G-force from the sharp pitch caused Leeward to black out, and then fall on his control stick, which made the plane turn and then nosedive into the ground, said Jackson, who has been racing these planes for 20 years.

SO, my synopsis is:
Leeward , having gone faster than he ever had before, with an opportunity to pass into second place, disregards the instructions and trims against the nose up forces resulting from his increased speed.
He over-stresses the tab and then it breaks off the aircraft, resulting in a massive nose up force that he cannot hold against.
This force is sufficient to render Leeward unconscious and is testified by the deployment the tail wheel.

We all know what happened after that...

reason for edit, update reference

Gilerguy, it was Matt Jackson, president of the Unlimited Class at Reno, who was quoted as having said that about not using the trim. Think the quote I saw was on a legal or insurance website discussing liability, linked from WIX.

Hang on a second. How can using the trim tab at speed, which then breaks off NOT be a design flaw?

My reading of those comments from Matt Jackson come across as "these aeroplanes are safe, it was the pilot wot caused the accident."

Which is invariably the reaction after any accident when the pilot is not around to defend themselves. He sounds as if he's parceling blame over to Leeward to protect the rest of the class.

The old "it's purely pilot error" comments are invariably rubbish. There maybe an element of it, but for it to be the be all and end all is generally not usually correct.

Matt Jackson should probably learn to shut his face and wait for the actual report to come out.

Sounds like a perfectly logical explanation, if speculative.

What else would you use it for? To make the tea? Sounds like he has been misquoted or something.

Thanks for those, amazing indeed, just shows how heavily modified the Unlimited class aircraft are, I wonder how much of the original warbird P-51 metal there was left?

RE: articles that quotes Matt Jackson and amazing photos, what a work of art
 

1. If this fellow truly believes trim tab use caused the accident, then the racers should be required to bring a set of elevators WITHOUT trim tabs and change to them before racing. With the money that is obviously spent on these aircraft, a spare set of elevators should not be excessive. My experience has been that leaving a function operational in the cockpit and telling pilots not to use it does not have a hight probability of success.

2. Trim tabs usually fail because of flutter, not static strength. Flutter usually occurs with a lightly loaded surface (one is is relatively faired with the control surface) not one that is highly loaded.

3. The pictures of the aircraft construction. The trim tab has a single rod actuator. For an aircraft that operates at this speed, a dual rod actuator would be much better. Also the elevator mass balance appears to be entirely in the horn. Again for aircraft operating in this speed range and under these conditions, spread out along the leading edge of the elevator would be better.

4. There appears to be a huge amount of space in the vertical stabilizer near where the leading edge of the horizontal attaches. Just cries out to have an electric actuator installed, the entire stabilizer made trimmable, and the trim tabs done away with altogether.

5. The work that was going on in the shop appears to have been first rate.

gileraguy

gday. You have a 'belief' the photo predates the accident? That is interesting, and I can't respond, I never question a man's Faith. If the photo is from Tim O'Brien, it is Gold Standard. I know him, he is a fixture in the local aviation community, and his work is legend.

Somebody missed that blemish in the walkaround? I seriously doubt that. The a/c was cleared to the line looking like that? Have you reviewed my sketchy post on the mechanicals if it is real? Thoughts?

I think the video that shows the Ghost's hesitant over roll gives up what happened to cause the Pitch UP. It shows a mechanical issue (W/T is not eliminated), that the pilot reacted to: the ('extra') Roll left was not an indicated input for his flight path, so it was uncommanded. The response of the a/c in rolling back to the right shows a 'correction'. What remained of the a/c's flight path seemed gentle, and controlled.

The Pitch Up was almost certainly Pilot induced. It didn't resemble a casual exit of the circuit, it was in response to a Nose drop. An over-control, most definitely. CG is not set for stable, cruise flight, and the response in Pitch is touchy. Adrenaline and emergency are not conducive to ice water in the veins.

Pilot's vasculature is an issue, he seemed healthy and fit. However, there is a reason the rules start to discriminate against the aged in aviation. The wrinkling of the belly skin shows an inordinate amount of undesigned for stress, do you agree?

Regardless the cause, or its timing.

Question for you. Can an a/c like the Ghost Stall with a Pitch up of 60 degrees? In a 90 degree Roll?

Anyone notice that the tail wheel is not down in the wrinkle photo?

gh

Completely unrelated but when being taught for competion finishes in glider flying which is essential a conversion of all altitude into a Vne dive and fly-by; we were taught to leave the trim in "high speed cruise" and never trim away all forces.
Any momentary lapse of concentration and corresponding relaxing of the stick force would cause the glider to climb and not descend into the ground.

I cannot recall the source since I was just google-ing a couple of nights ago but here it goes;
The original P-51 design had a sea level max speed of 375 mph, hence a certain angle of incidence of the tail plane.
If this was not changed on the race aircraft you would need excessive nose down trim deflection which has the trim tab stick out further in the airflow.
This is what apparently caused the flutter and trim tab failure in the accident in the 90-ies.
From the slow motion accident sequence it is clear something failed prior to trim tab seperation. Might be the actuating rod or hinge mechanism.
It is hard to believe that somebody with this much racing experience (120+ races) would make a what would appear to be a "rookie" mistake.
But then again, accident reports are filled with experienced pilots.
I have to admit that despite the obvious tragedy this is fascinating stuff.
Like the death of Ayrton Senna.
Ayrton Senna da Silva

gearhorn

Of course. Did you notice how many G the pilot was pulling prior to the "climb"? Just because the a/c is not gaining or losing altitude does not mean it is not experiencing wicked G.

Technically, the "additive" left ROLL is a wing drop, since the a/c wings are nearly vertical. In this attitude, again technically, the a/c is actually in a wicked climb, though you may call it a turn.

Once again, if those wrinkles are real, the cause can be determined, and the most likely cause is stress beyond critical design, in a commanded climb (OR PITCH UP). Or in an uncommanded (trim commanded) climb.

This means that the wrinkles preceded the TailWheel deploy.

Point of fact, the a/c may have experienced its most emphatic G load prior to the ascent. This means Leeward was likely incapacitated before the a/c started the ascent. Once 'established' in a manouver, the G relents, obviously.

If so, then manouver entry (PITCH UP) caused the buckling of the skin, the incapacitation of the pilot, the deploy of the TW, all before the dramatic gain in altitude, which was a result of the failure, not the cause.

Oil canning is not ideal, but nor does it mean the thing is about to rip itself apart either. That pricture might be significant, it might not.

No disagreement from me. My assumption quite obviously is that it is significant, however. Most design considerations transcend the 'normal' in Ulimited, eh? Do we have a spec on the skin in that area? The structure beneath?

I take your point

ps in slomo, do you see the tab depart, near the apex of the climb?

NTSB Press Briefing Reno Nevada (sep 18, 2011)
 

Reno crash telemetry data.
 

Here are some telemetry data from the P-51 “Galloping Ghost” which crashed at Reno.

Airspeed around pylon 7 - 495 mph.

When the trim tab broke off the aircraft pitched up pulling 21 G's and airspeed reduced to 375 mph. (Tail wheel popped out, pilot slumped below view).

21g - No way.

The Mustang limiting g was/is about 8 or 9 and fitted with a system to support an anti-g suit which was no doubt removed from the Ghost.

If 8 g, then design ultimate would normally be 12 g at which a wing is supposed to depart and at some lesser g if rolling.

Just cannot believe that the shortened wings would not fail at much over 12g.

Comments please from an aircraft designer or structural engineer.

Milt...

Yes - 21g seems unlikely. However NB at what the 8g / 12g ultimate was for - empty weight 7000lb, MTOW 12000lb.

Shorten the wings, take out a lot of weight, light fuel load (in fuselage tanks), and suddenly your ultimate 'g' increases by a large amount. Clearly it will take someone familiar with the structure / design to know what should fail at 12g / wing bending relief aspects etc. But I would not be amazed to see something approaching 20g not resulting in major failure.

NoD

Being a data recorder, I wonder what the intergration time was for that "21g" if it was very small then I would imagine a transient spike might be possible.

Though to have a small intergration time it means recording lots of data, hence more weight due to storage.

I don't know what the unaccelerated stall speed of the Ghost would have been but 21G would require that the airplane be moving at an indicated airspeed of about 4.5 times that speed. The listed speed of 495 mph seems too high to be an indicated speed. Maybe GS or TAS but not IAS or CAS as that would be close to 550 mph in the turn at over 5,000' density altitude. Average lap speeds didn't even approach that, though top speed down the "valley of speed" could. I'd guess the IAS as being closer to 450 mph max. At 450 mph, the unaccelerated stall speed would have to be 100 mph to make the 21G credible. Interesting. I wonder what that stall speed is...

Still some mystery here.

Is it not the case that the ratio has to be at least 4.5? So any unaccelerated stall of up to 100mph would do it?

(Subject to the disclaimer that I have considerably more experience in arithmetic than aeroplane design...)

The actual indicated airspeed would have to be 4.5 times the unaccelerated stall speed in order to pull 21G before stalling. So the unaccelerated stall speed would have to be 100 mph. At any stall speed less than 100, it could pull more than 21G at 450 mph IAS. (not accounting for energy lost before reaching 21G)

Edited to add that if the unaccelerated stall speed is greater than 100 mph, the 21G is a stretch. And 21G seems like more than the trim change with loss of tab would produce, but that's pure conjecture. Maybe if there is enough good video to measure the angular change of momentum over time, the load factor can be calculated that way.

#180 @ 9:00 One sees the actual departure of the trim tab from the airframe. So, "broke off" is not an accurate way to describe the tail damage. It broke, but "off" came later, near the apex of the ascent.

The Roll to wings vertical prior to the climb is interesting in that it may involve other than control surface deflection. Look carefully at the sheet metal on the underside of the wing in the slomo. Either the light is changing, or the under surface is "unloading", losing its dynamic "crush" in a ....STALL?

21G? No comment. Leeward was in high G well before the mini roll left, and may have been impaired/incapacitated before the climb itself.

Them's some very short wings. AoA at the "Roll"? Anyone?

addend. Watch the slomo carefully. As the a/c is "rolling" left, notice the NOSE dropping, alot. The a/c then looks to have recovered itself, and the Pitch Up is dramatic, very quick. So this unusual 'snap' left may have been the port wing dropping in STALL. It would be the one to drop out, as Leeward arrested the left roll 'turn' he had just made, its velocity being slightly less than the right wing, due turn radius, and its aileron increasing its net AoA, drag.

It is the Nose Drop that would have violently overloaded the tail feathers, producing the longitudinal collapse of the tail section evident in the still photo (wrinkling). So if the geometry of the image is accurate, the photo will have been exposed in the split second before 'climb'.

Just as the tail collapsed, it also Pitched the a/c UP. I think the pilot was a passenger after that Pitch change.

At Nose Drop, there would be large negative G. At Reversal into climb, large positve. Add Roll, and Yaw, and the human body may have exceeded its physical limits, as well as the tail.

I would think that from the video ,at Pylon 7,that GG hit wake vortex from Strega and Voodoo,who were approximately 4-5 secs ahead,GG having overtaken `R-Bear at this point.That may have triggered the failure of the left tab,the Mustang has two trim tabs,but there does appear to be a difference in deflection,looking at the `oil-canning` pic.#207 ,and the other left -side shot.#162.
The EAA article mentioned earlier,Jimmy says the ac stalls about 130 mph,but cleanly. I would estimate the wing area at about 175 sq.ft,and at about 8000lbs a wing loading about 46-50 lbs/sq.ft.,so I would guess a peak `g` of about 15.. but what is telemetered depends also on the position relative to the Co G.
Whilst it has been poo-pooed ,the seat may have failed,depending on its mountings; it also looks from the other slideshow link,that the harness mounting is somewhere behind the seat and below the pilot` shoulders,ideally should be above/level,and attached to the main a/c structure...certainly used to be for F1 air-racing,when I were a lot younger..Similarly, it could be that ,being forced down and forward,JL could have been struck by the control column,in the chest/face/neck.
Just another point about the `oil-canning`,in that particular area is where the structure normally houses/supports the radiators; however I would be surprised if the area had not been strengthened to accomodate their removal.
I would suspect that next year there may be aircraft with `trimmable stabilisers`back in vogue.
As an aside ,I think Matt Jackson should keep it zipped until the investigation is over..

This is a question, not an assertion; Believing that the trim tab failure caused a very unusual and uncontrollable pitch change, would it be possible for the aircraft to sustain a very brief pitch up to record the stated 21G? Could it occur, but not for long enough for the aircraft to actually stall at that G load and relieve itself? Like gust loading, could an event like this occur, cause various loads and effects to the aircraft, but not be sustained long enough for the aircraft to actually stall?

Pilot DAR

The first evidence of trouble is the anomalous roll left, and I am having trouble matching that up with a fouled or broken TT. There is some evidence of Pitch change prior, and that could be W/T, but again, I Think the snap left and Nose Down shows a high speed STALL. If you look at Pitch just after this slight roll enhancement, you'll see a pronounced drop in the Nose. The Ghost carries this Pitch down only briefly, and starts its ascent right away.

I think Jimmy was tighter to the pylon than Strega, Voodoo, and would have passed their W/T 'above' (actually, "inside"), as it settled outward. This upset looks very much like a too-tight turn, a quick STALL, and autonomous recovery. The fuselage distortion is quite indicative of an overloading downward moment, a result of exposing the tail to extreme aspect at this remarkable speed.

For me, it is easier to see the Trim Tab fracture as a result of, rather than a cause of, the climb. Again, it was in the airstream in the up position to begin with, and its exposure would have been at an even steeper AoA than the HS in the brief STALL aspect. The elevator would have seen some airstream relief in this aspect, and the HS would have been the source of the energy that overloaded the Fuselage in the area of the Buckled skin.

To answer your question, if the NOSE drops, the G would be quite negative, and a starting point for the ensuing positive G associated with the climb. As a reversal, I consider these values to be additive, and the damage resulting quite alarming. Both to the pilot and the airframe.

21G? No comment.

In an earlier post, I remarked that looking at the crash video, if the speed is about 500mph and the time from horizontal flight to vertical is about 2.5 seconds, a back of the envelope calculation suggests approx 15g initial G.

That's no aerodynamics calculation, purely on the physics of something at a certain speed changing direction in a certain amount of time. 21g may have been a peak figure for a short amount of time.

The video shows a sudden and extreme G whilst the a/c is wings vertical,
and while horizontal flight path is evident, the G is experienced 90 degrees out of phase, relative to path vector. It is at this time the T/W starts to come out. So I think it important to consider that the G loads were not consistent, they were experienced in rolling, yawing aspect, not just in "Climb". They also differed in Negative/Positive direction. It also would support some uncommonly high G values.

I think the camera is a constant, it shows no vibration, and the lighting, while variable, cannot account for the Torsional fuselage movement v/v the wings, and there is evidence of sudden and out of rig airframe displacement. As a/c is rolling out to Right, Note both elevators in extreme ND. This is either the result of dramatic aspect increase to the airstream via pilot input, or the result of exposure to dramatic airflow over the top of the HS, resulting from sudden NOSE DOWN. It is too rapid for Pilot input, so I think the latter. Bear in mind, that if the control surfaces are being back driven to this extent, continuity with the stick may have been lost. As the STALL is recovered, the elevators go neutral, then deflect up, again from airflow, not PILOT, resulting from the climb. As speed is lost, the controls seek neutral, and the aspect becomes gentle, as if the pilot were in control.

my bold

Good point. It's possible that between the video and the telemetry a reliable model of the events can be reconstructed if common time references can be worked out. The vehicle recorders lab at NTSB has an admirable success rate in this area, so I wouldn't rule it out.

It will interesting to see what investigative documents are posted on the E-docket library when they get to it. (nothing yet as of today)

Yeah, I would have thought Jackson might want to keep a lower profile these days.

Web find for you guys from last year I would guess

http://i6.photobucket.com/albums/y23...0/P9166937.jpg

no idea who to credit though

Do you see it?
 

I've been looking over the video posted by Knot4u in post #181 and there seems to be some activity around the elevators during the brief left roll at the beginning of the accident sequence. It is very fast, but to me, the outline of the elevator trailing edges becomes briefly asymmetrical and the port elevator seems to move up sharply coincident with the left roll. The motion is what is catching my eye, but when I stop frame, the contrast is not good enough to be sure of anything.

Other significant items visible are the tail wheel dropping just after the aircraft rolls wings level and begins to pull up.

If you watch the trailing edge of the port elevator during the pull up, you can see the trim tab begin to break loose and then separate, roughly at the time the top of the aircraft is pointed at the camera.

Just a personal opinion here, but the initial wings level at pull up seems to be the result of lateral control input, and the beginning of right roll shortly after commencement of the pull up probably marks the beginning of GLOC. The pull up itself was the result of changed aerodynamic configuration and was not commanded.

If 21 g acceleration were to be generated, it would have to be an impulse. Sustained 21 g would almost certainly fail the engine mount. They just don't build that much safety factor into aircraft.

There are a few "telemetry reports" on the web that are at variance with the telemetry report with 21 g of acceleration.
Here is one from the bearhawkgroups.com website dated 9-23-2011:
It may be that these reports can co-exist and merely report different moment's telemetry data.:confused:

I view the entire flight path from pull up to impact as most nearly representing a high g barrel roll, and there was no significant slacking of g over the top. The curvature in flight path was extreme and continuous to my eye.

Those predicting a broken neck for the pilot as a result of the high g, are probably wrong. One of our F-4's snatched 12.5 g which greyed the crew out but they suffered no lasting effects from the g exposure. The F-4 needed a lot of rivets replaced in the wings and tail though. The human body is very tough.

Machinbird

Howdy. The 'add' roll left, at the moment one expects a roll right for level, is consistent with a wing drop on the left. With input right aileron the left aileron drops into the airstream, creates drag (lift) whilst the right aileron tucks up and lessens drag on the right wing. As you know, of course.

Is it possible this was a STALL? I pick up a NOSE drop after the wings reach vertical, and quickly followed by regain of lift, and NOSE up.

When the tail comes back into view, there is a marked torsional sequence of the Tail Feathers relative to the Fuselage, likely caused by asym downforce after the TT broke.

I think the TT broke off as a result of drag, past critical stress, aiw. The Trim Tab loss is not on its own sufficient to explain, with these other clues apparent.

This Torsion would explain the buckled skin in the still photo, but so would a Nose Drop post stall.

Keep after the video, I think you will see rapid and extreme Pitch aspect changes, coincident and following the short snap to left. This Pitch is certainly what caused the TW to drop out, since clearly it was dropping out before the climb.

This is suggestive to me of the massive g load at this point in the sequence, prior to 'climb'. Carefully watch the entire airframe as it reacts to the rolling, it is in extreme distortion, the elevators and wing undersides are distorted radically, and the flight path is 'shaken' in the camera lens.

Let me know if you cannot see the Torsional flexion in the tail relative the fuselage, I can find the exact frame, I think.

Ah, the Phantom

So, for the rest of us, shouldn't we be looking for a reason the left wing drops out? Instead of why a Trim Tab let go? The 'Roll' follows the precise timing for a reversal into Right Roll, and if the rest of you can't see the aileron on the left wing dropping down, I think I see it. What does a wing do when it is asked for more lift at critical Lift? It Stalls, drops, and induces a Nose Drop in Roll, with Yaw. All of these quite visible in the video.

The other explanation is that the Tail, having lost a tab, imparts twist into the fuselage, and this causes the unwanted Roll Left. This is evident from the video, but did it cause the roll back to the Right? The twist is clockwise as seen from the back, consistent with a loss of downforce on the left HS. Depends on the position of the broken Tab. Did Leeward have ND cranked in, or NU? And did the tab break as a result, or did it cause, the upset?

Pretty powerful Tab.

I can't question your opinion re: the pilot's spine, but the environment in the P-51 is not conducive to survival so much as it is to success. I certainly don't criticize your experience in the F-4.

Here, there is a possible transient load of 21g. Almost twice that your buds survived. He was ok before the Roll, we assume. There is no provision for helmet anchoring a la NHRA, and the straps are less than useless in regimes outside their design, which is mostly for straight and level. If you pick up the PITCH changes, the distortion of the airframe, the TW loss of stow, the Rolling moment, and the YAW, then consider he is wearing coveralls, tennis shoes, and sports a brain bucket built for visibility, I don't like the chances for his spine to survive.

But. It is moot. Grey is enough to put this aircraft into the asphalt. Not even grey, for that matter. The stick is long, and wants deliberate and accurate movements. It is alive. Moving it in 3G is not without its challenge.

Right roll!
 

Check closely - just before the sudden left roll, it seems to me the plane is trying to roll RIGHT, very slight, almost imperceptible - but definitely there. In particular, just before tucking the left wing under, it seemed the right rolls were about to get out of hand so he overcorrected with left roll INPUT, and then snap - too late.

In other words, he's in a fast steep turn with highly modified aerodynamics for his airplane, and it has basically stopped flying normally and is trying to roll right - probably because the outer (right) wing is stalled. It's in a high-speed stall induced by too much speed through a turn.

-drl

deSitter

There is that, and it comes at a reasonable point in the turn for the pilot to start rolling out level for the show center pass. A Right Roll involves deflection of ailerons, left down, right up. this changes the lift and load on each wing. If the left wing exceeds its critical Lift, it will STALL, and the a/c will now reverse, and Roll Left. It is not a good thing, because it imparts Yaw to the airframe, and enormous loads on the Tail, and Heavy engine (see Machinbird, above). As the Nose drops, (increases the radius of the "turn"), speed/Lift is regained and the a/c (wing) starts to fly again. This is too quick for it to be under the pilot's control, it is simply what aircraft do. The upside is that the a/c recovers aero flight on its own. The downside is it overreacts, and starts a....phugoid. So the climb after the loss of the TailWheel structure was likely a natural, and the roll, descent at the top was a bottom wave of the phugoid.

If you look carefully at the underside of the a/c, you will see the ambient lighting flaring on the skin. This is not to do with the light, but with the orientation of the skin itself. This a/c, like most others, is basically a balloon when flying through the air. Pressure from the airstream forces the skin inward against its formers, and substructures, and a balance is reached relative to the speed, and attitude of the a/c. When a deviation in flight path or airloads occurs, the skin responds, as does the structure beneath it. A Stalled wing, for instance, will unload the skin and change the way the light reflects upon it. The a/c effectively, "bulges" where the pressure has released, and this is evident, along with a startling re-orientation of the airframe with the airstream, what you see as an emphatic 'wobble', producing large G deviations from "Normal".

This "Snap" roll left is not commanded, and it is definitely not reversed, by the pilot. It is far too quick to have been input by Leeward. I am magnifying the video to see if I can capture the Left aileron bulging in to the airstream at the TE, but so far...

Can this event have been instigated by the Trim Tab failure? Possibly. It would have also caused a Pitch UP, and an adverse and torsional roll also.

The Tail is seen rebounding from this torsion in a dramatic out of rig aspect with the wings, look closely, and see the airframe rock and roll with this out of rig condition. (It is quite brief, if it had continued, the a/c would likely have come apart at this point.) This misaligned and reorienting event may have produced what was heard as a pop. It is not impossible some substructures broke, or fractured. It may have been the TailWheel snapping away from its lock.

...or more logically, the result of wake turbulence from the aircraft ahead of him.

Wake Turbulence is certainly a possibility. The aircraft in entering its last turn exhibits an instability in roll that could be Wake Turbulence induced, but consider that for the instability to remain uncorrected points instead to the inherent instability of this a/c at speed. WT is a fleeting event, it flies its own path, and it does not conform to the flight path of the following a/c.

Was the Ghost In/Out of W/T? If the procuring cause of the upset, it is unlikely to have remained in the Ghosts path, and the upset/crash was a result of the initial snap Left, whether a broken tab, overcontrol, W/T, or STALL.

On the back straight, Ghost descends and levels, reaching its likely maximum speed in the circuit. The turn imparts high G force and the turn tightens as Leeward rolls to ~80 degrees.

Ghost is in passing mode, flat out, and the psyche is powerful. I think 177 is as tight to this pylon as any in the circuit, and loss of control at its most susceptible.

Roll Rate on this a/c is rapid, far higher than the factory model with ten feet less span. Similarly, the ailerons are half length, and it would be interesting to know if they were clipped Out/In, or In/Out. This is critical, since ailerons are airfoils, and subject to STALL just as any other.

So, maximum velocity, roll rate; minimum wing, aileron. Test Flight.

Am I alone in being transported back in time to lectures in aerodynamics by Lyman's posts?

All good stuff, but 'Granny', 'sucking', and 'eggs' come to mind.:)