PPRuNe Forums

Go Back   PPRuNe Forums > Non-Airline Forums > Private Flying
Forgotten your Username/Password?

Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.


Reply
 
Thread Tools
Old 27th Sep 2011, 08:07   #201 (permalink)
Gnome de PPRuNe
 
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 50
Posts: 3,424
A suggestion on the WIX site is that the aircraft may have encountered wake turbulence from the preceding aircraft, hence the initial increase in left bank to what appears to be 90 degrees or more.

Also from WIX, 9g would have been sufficient to bring the tailwheel out - did that happen when Voodoo's trim tab went?
treadigraph is offline   Reply
Old 27th Sep 2011, 21:44   #202 (permalink)
 
Join Date: Dec 2001
Location: FL, USA
Posts: 1,471
Quote:
Very good article from a veteran aviator about what caused the Reno crash.
I have to call BS on that broken seat article. The pictures in post #157 clearly show no room or open area behind the seat.
Besides that is where the custom designed cooling system was installed according to the EAA article.
For now I'll go with the black-out after pitch up presumeably because of a malfunction of the elevator trim. Something that has happenend twice before with similar aircraft during the same type of race.
B2N2 is offline   Reply
Old 27th Sep 2011, 23:08   #203 (permalink)
 
Join Date: Nov 2008
Location: near Gatwick
Posts: 269
Quote:
I have to call BS on that broken seat article.
Agreed. The author seems to imply that the violent pitch-up caused a massive g-force directed backward along the fuselage, which is clearly nonsense.
In such manoeuvre the g-force would be directed mostly downward, towards the floor of the aircraft, i.e. no sliding back. Instead, head slumping forward, especially if the seat belts were not fully taut.
Deeday is offline   Reply
Old 27th Sep 2011, 23:22   #204 (permalink)
 
Join Date: Dec 2004
Location: East Anglia
Posts: 836
This photo has been posted elsewhere. It seems to show buckling of the fuselage.

Zulu Alpha is offline   Reply
Old 28th Sep 2011, 01:01   #205 (permalink)
 
Join Date: Jan 2002
Location: MIA
Posts: 11
I think when he did the 10+G pull up when he passed out who knows what his arm and body did to the stick. We saw the whole thing overhead and it appeared no throttle or control movements were made, it just was a projectile not controlled by anybody. Even though it looked like it would hit our seats for a couple of seconds I think time slowed down in our brains and it was less than a second after reviewing the videos.
keezy44 is offline   Reply
Old 28th Sep 2011, 01:21   #206 (permalink)
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,122
#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.

Last edited by Lyman; 28th Sep 2011 at 01:37.
Lyman is offline   Reply
Old 28th Sep 2011, 01:51   #207 (permalink)

Life's too short for ironing
 
Join Date: Dec 2001
Location: Scotland, & Maryland, USA
Posts: 1,026
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
fernytickles is offline   Reply
Old 28th Sep 2011, 03:55   #208 (permalink)
 
Join Date: Sep 2011
Location: Nevada
Age: 48
Posts: 17
Just found this, amazing photos, what a work of art
WarbirdAeroPress.com
xmh53wrench is offline   Reply
Old 28th Sep 2011, 07:43   #209 (permalink)
 
Join Date: Jul 2008
Location: adelaide australia
Posts: 204
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

Last edited by gileraguy; 28th Sep 2011 at 08:39.
gileraguy is offline   Reply
Old 28th Sep 2011, 08:25   #210 (permalink)
Gnome de PPRuNe
 
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 50
Posts: 3,424
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.
treadigraph is offline   Reply
Old 28th Sep 2011, 09:00   #211 (permalink)
 
Join Date: Mar 2000
Location: U.K.
Age: 36
Posts: 3,113
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.
Say again s l o w l y is offline   Reply
Old 28th Sep 2011, 09:04   #212 (permalink)
 
Join Date: Aug 2007
Location: Chedburgh, Bury St.Edmunds
Age: 72
Posts: 1,032
Sounds like a perfectly logical explanation, if speculative.
JEM60 is offline   Reply
Old 28th Sep 2011, 12:15   #213 (permalink)

Life's too short for ironing
 
Join Date: Dec 2001
Location: Scotland, & Maryland, USA
Posts: 1,026
Quote:
made the mistake of using his “elevator trim tab” to control his plane
What else would you use it for? To make the tea? Sounds like he has been misquoted or something.
fernytickles is offline   Reply
Old 28th Sep 2011, 12:15   #214 (permalink)
 
Join Date: Sep 2003
Location: Retford, UK
Posts: 469
Quote:
Just found this, amazing photos, what a work of art
WarbirdAeroPress.com
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?
MichaelJP59 is offline   Reply
Old 28th Sep 2011, 13:29   #215 (permalink)
 
Join Date: Sep 2011
Location: San Antonio Texas
Posts: 6
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.


FoundationMetro is offline   Reply
Old 28th Sep 2011, 15:37   #216 (permalink)
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,122
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?

Last edited by Lyman; 28th Sep 2011 at 15:48.
Lyman is offline   Reply
Old 28th Sep 2011, 15:56   #217 (permalink)
 
Join Date: Mar 2008
Location: Los Angeles
Posts: 5
Anyone notice that the tail wheel is not down in the wrinkle photo?

gh
gearhorn is offline   Reply
Old 28th Sep 2011, 15:58   #218 (permalink)
 
Join Date: Dec 2001
Location: FL, USA
Posts: 1,471
Quote:
What else would you use it for? To make the tea?
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
B2N2 is offline   Reply
Old 28th Sep 2011, 16:14   #219 (permalink)
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,122
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.

Last edited by Lyman; 28th Sep 2011 at 16:24.
Lyman is offline   Reply
Old 28th Sep 2011, 17:27   #220 (permalink)
 
Join Date: Mar 2000
Location: U.K.
Age: 36
Posts: 3,113
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.
Say again s l o w l y is offline   Reply
Reply
 
 
 


Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT. The time now is 17:45.


vBulletin® v3.8.7, Copyright ©2000-2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
© 1996-2012 The Professional Pilots Rumour Network