Fwd: Reno Air Race - Probable conclusion to fatal crash

I received this from a pilot buddy and thought it would interest several here. The attached pics are at http://www.flickr.com/photos/67743492@N07/sets/72157627592884885 /
If that doesn't work let me know a better way/site to post them at. Art
----- Original Message -----
Thought you may be interested in seeing this. My senior partner is David Price Sr. who raced in the Reno gold and silver classes in a P-51 for 6-7 years. He had two P-51s, a hot modified racer with one seat, (he has since sold that as he does not race due to age) and the second a two seater, basically stock exterior but with a hot motor, that he still flies. He owned the company Supermarine (a aircraft fuel and lease company) and currently owns American Airports which manages public airports across the US and some Pacific Island. He also is the benefactor and owner of Museum of Flying here in Santa Monica. This version of what happened is probably what happened, mechanical failure, tremendous & violent yaw causing death or unconsciousness immediately, and the crash. Gary
From another friend that has known Jimmy and Erik for many years, below you can see what he learned today, when he spoke to Erik, the crew chief of Jimmy Leeward's flight crew
HI Dave;
My response was on my Iphone and a few mis spelling...pretty tough break..my guess that is the end of the reno air races.....
Erik Hokuff who is Jimmys crew chief and I had a short chat yesterday , and he confirmed the tail wheel was deployed from massive G load and tab effect as follows.
Similar event happened to Voodoo Mustang years ago...Bob Hannah was flying and was put to sleep for a bit..woke up with head forward of control stick and hands by feet...sat up and had several hundred feet to recover..
Everything changes when the angle of incidence is modified both tail plane and wing....and probably didn't help that Jimmy was mid seventies regarding G-LOC....my guess is he could well have snapped his neck on a 12 to 15G instantaneous pull like that....you can see in the pic below that Jim is nowhere to be seen..my guess is he was out cold for the whole event starting at trim tab separation...I believe his mayday was from flutter response as he was passing Stu in the Rare Bear just prior to tab departure.
Jeff
<pic 1-3 moved to above link>
On Sep 18, 2011, at 8:43 AM, DK Gorrell wrote:
...DkG
Subject: Two Questions We have all seen the pictures of this tragedy at Reno, but I have two questions.
1. Would losing the trim tab on one side of the elevator really cause this type of loss of control?
2. Why is the tail wheel extended in this photo, on a plane where everything is done to reduce drag and increase speed?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Great photos, I was starting to wonder where all the cameras where. Thanks. Prop wash isn't good if I read that correctly. Always wanted to see that race.
SW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/20/2011 8:11 PM, Artemus wrote:

Yes.
As an airplane travels faster the wing makes more lift. To keep from climbing the nose is pushed down.
While the trim tab looks tiny compared to the rest of the aircraft, it is really all that is holding the nose down.
Trailing edge of the tab would be up which forces the trailing edge of the elevator down, thus pushing the the nose down.
Sudden loss of that tab means a sudden nose up - and at those speeds if would be exceptionally violent pitch up.

The up lock broke - due to the violent pitch up.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Same thing happened to Bob Hannah, but happened while "all" that resulted was a quick 10G climb and a short blackout. And, he quit after that.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 21 Sep 2011 05:40:36 -0700 (PDT), Dave__67

I've been thinking about this situation. A trim shouldn't EVER be holding back a violent tendency for a plane veer off! If you've modified a plane that wants to pull a certain way FIX the problem don't lean it all the way on the band aid. & this has happened before?
Cock the vertical stabilizer like is a given for the vertical. If you still have to trim it, do it for the lower speeds. Its an unlimited race plane, make it fly like shit slow and straight fast.
Having the stick yanked out of your hand cause of a trim tab is crazy.
SW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/21/2011 8:58 AM, Sunworshipper wrote:

It's just not possible for aircraft with such large speed ranges. (And yes, that includes the airliners as well. They work the same way)
Maneuverability and stability are opposite ends of the same string. A really stable aircraft will not be very maneuverable. A maneuverable aircraft will not be very stable. That is, of course, without modern fly-by-wire control systems. But even then, the basic aerodynamics are that way.
This is a good synopsis, if you are really interested. soliton.ae.gatech.edu/people/lsankar/AE1350/Lecture.11.ppt
Or if you really have the balls for it... http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-333-aircraft-stability-and-control-fall-2004/download-course-materials /
Take particular note of Static and dynamic stability, static margin, and the effects of increasing or decreasing stability margins.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

?
This is interesting, one can take courses for free?

Sounds good and all, but I don't believe it. Loosing a trim tab shouldn't cause multiple G forces.
SW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Believe it or not - at that speed it WILL.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
says...

>http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-333-aircraft-stability-and-control-fall-2004/download-course-materials /
No, you can download some of the course materials, in some cases including the classroom lectures. You don't get one-on-one with the prof nor do you get your assignments graded.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/21/2011 5:59 PM, Sunworshipper wrote:

Doesn't matter if you believe it or not. That's how it happens to work.
The forces involved are tremendous.
And that tiny little tab is what makes it all happen.
Think of it as the base of a transistor? A tiny amount of current controlling a larger current.
They are, after all, just air currents!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Perhaps he doesn't understand what a trim tab does. It does NOT act as an elevator. What it does is deflect the elevator, and the elevator's movement would cause the aircraft to pitch.
But even if he doesn't understand that, I also don't believe it. I'm a pilot. There is NO excursion of a trim tab one cannot properly correct for with the stick. And one that's broken loose, so it's hanging by one corner of one end would not act to effectively deflect the elevator surface. You would get some "flutter", but not any severe deflection one way or the other.
One thing that sometimes breaks trim tabs is too forceful a throw of the stick (below or at maneuvering speed). Trim tabs are delicate. Elevator shafts or hinges are not.
If he'd been above maneuvering speed (which is damned high on a Mustang) when such a deflection occurred, he'd have torn off a wing at the root, instead of a trim tab.
I don't know if the Mustang had lever controls or cables -- likely cables to the elevator. A broken or disconnected elevator cable (it would use a pull-pull system of two cables) would cause a rapid deflection to the neutral position (it's most streamlined position) unless a lot of force was being applied to the still-good half of the cable pair. THAT wouldn't happen, because the remaining cable would act to move the elevator in the wrong direction from that in which you wished it to go.
You can do a lot of maneuvers without a rudder, or without ailerons with enough dihedral in the wings, and even do some pretty fancy airspeed- controlled rate-of-descent tricks with a stuck elevator, so long as it's stuck slightly up or neutral. But you can't control the aircraft at all with an elevator that's just flopping around loose. And with only 'down' control, you can change the trajectory, but you cannot avoid a crash.
I had a friend who took a newly-annual'd MU2 for its shakedown, and forgot to check aileron throw before he rolled out. They were reversed, and he'd already rotated and retracted the gear when he finally noticed. He got it around the field and landed it on sheer nerve and a damn-lot more skill than I could muster in that situation. But they were reversed, not broken.
However, I believe those racing planes have redundant cabling to all the control surfaces to protect against the likelihood of one letting go. So more likely, I think he busted an elevator control horn, which would act just like a broken cable, and he couldn't correct in the desired direction. So he used the opposite throw to try to guide his up-scaled lawn dart away from as many people as possible. Which, if it's proven, would make him a hero.
LLoyd
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What do you fly, Lloyd? What it the stall speed to max speed ratio? When it get's up to 5 forces get seriously strong.
And note, the photos DO show the trim tab failure.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You don't read posts before you answer them, do you?
Check back on what I said. I realize the trim tab failed. I can also see the mode of failure. Duh.
Lloyd
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/24/2011 6:01 AM, Lloyd E. Sponenburgh wrote:

Yes Lloyd, I read it.
If we are going to be huffy maybe I could reply that you don't know much about aerodynamics and didn't bother to find out before you posted.
But I generally don't go into that kind of reply. IT just leads to a pissing match and a lot of hard feelings.
So, instead, let me offer the following... Understand that this is very simplified approach to calculations of aerodynamic forces, but it valid in subsonic flight.
Equation: Lift = .001188 * (Coefficient of Lift) * (Velocity Squared) * (Wing Area)
.001188 constant allows: Sea level density altitude Velocity in MPH Wing Area in Square feet
And, of course, the equation can be rearranged to solve for any of the included terms.
So...
Take off performance: (given) Stall Speed = 100 MPH Wing Area = 235 SqFt
CL calculates to 1.66
Max Speed performance: (given) Velocity = 500 mph Wing Area 235 sq ft
CL calculates to .0066 (!)
If, at high speed, the nose pitched up to the take-off angle of attack (thus providing the take-off Coefficient of Lift) (given) Velocity = 500 mph Wing Area = 235 sq ft
Lift calculates to 249,340 pounds. For the 10,000 pound weight that means 24 Gs possible load factor.
Like I said earlier, the forces are tremendous! The thing that modulates the wing's lift is the tail. The long arm from wing to tail allows smaller forces to control the pitch of the wing.
The trim tab in question is located at the very aft edge of the control surface (elevator, aileron, whatever). The distance between the hinge points (elevator hinge and trim tab hinge) define the trim arm. That's how the small trim tab can deflect the much larger elevator, and the elevator control the pitch of the much larger wing.
Now, yes, there are other approaches that can be taken. Tailless (flying wing), tandem wing, and canards. But they all have to face the same issues.
Tailless types have very short tail arms and are thus very limited in their pitch authority. That usually means higher take off speeds.
Canards are kind of in the same category. The forward control surface (the canard?) is designed to stall before the wing stalls. Has to be this way to avoid the serious problems of a deep stall - where the wing stalls before the canard - with an uncontrollable pitch up resulting. Again that usually means higher take off speeds.
So the design of modern aircraft has evolved to the aft-tail arrangement because it offers the widest range of performance.
Conclusion: Directly related to the question at hand, this configuration also offers higher speed potential since it can provide higher pitch down forces at high speed.
I hope that perhaps this helps illustrate the "why" behind "this is how it's done".
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lloyd E. Sponenburgh wrote:

The MU2 has no aileroms, it uses spoilers.

I doubt the spoilers are visible from the cockpit. Maybe not a pre-takeoff checklist item.

Knife-edge, he could have used the rudder for pitch control.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't think it can be done in that aircraft -- at least not held indefinitely. That's a maneuver for a Sukhoy.
The P-51 has a generous rudder, but not big enough to hold a knife edge landing.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lloyd E. Sponenburgh wrote:

I don't think this P-51 pilot had time to be a hero, but I'm imagining what he might have accomplished given a few seconds to think it through. The knife edge idea was along the lines of steering away from the crowd, and cartwheeling elsewhere.
I once read about a quick-thinking pilot making an inverted approach, then rolling it over just in time for touchdown.
Also, a test pilot unable to break a stall crawled out of the cockpit out onto the nose to force it down.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then there's the aerobatic pilot who landed on one wing. Anything (almost) is possible if you have large enough control surfaces, and enough power. For the one-wing guy, if it had been the _other_ wing, he'd have died, because P-torque was part of what he used to save himself.
LLoyd
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
E. Sponenburgh" says...

Then there was this guy <
http://www.youtube.com/watch?v=-_EXtBEaBbs
.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've had two in-flight emergencies, and neither compromised the flight controls.
It takes one more thing, besides what we'd mentioned, to bring in a plane with a missing wing --- BALLS!
<G>
LLoyd
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.