Fwd: Reno Air Race - Probable conclusion to fatal crash

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

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.

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erything is done

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

everything is done

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

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...

Take particular note of Static and dynamic stability, static margin, and the effects of increasing or decreasing stability margins.

The plane hit 15 G's before impact. That makes the pilot's head weigh something in excess of 400 lbs, which could very well have instantly fractured the pilot's neck.

everything is done

?

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

everything is done

Believe it or not - at that speed it WILL.

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everything is done

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.

everything is done

You are overlooking the fact that as speed changes then so does lift and drag and torque, in a propeller driven airplane, and center of gravity changes dependent on load. There has to be some mechanism to balance these forces.

These changes are rather large - air pressure at, say 500 mph, is approximately 25 times that at 100 MPH. A control surface that is adequate at take off( say 100 MPH) would be 25 times too large at 500 MPH. Or to put it another way, a control surface that was adequate at

500 MPH would be 25 times too large at 100 MPH.

Cheers,

John B.

this type of

everything is done

Correction: "Or to put it another way, a control surface that was adequate at 500 MPH would be 25 times too SMALL at 100 MPH. Cheers,

John B.

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!

Better :)

Richard fired this volley in news:t9udnRpuu8VLueDTnZ2dnUVZ snipped-for-privacy@earthlink.com:

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

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.

From Coleen Sport Class Race 8 Crew

*Subject: : Galloping Ghost crash

• Ok... here's the skinny on the accident.... 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.

Here's the ?theory? of the crash from experienced racers.

*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 im ediately 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 *tail wheel 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.

*A friend of mine was supposed to be there but didn't go and he has several friends in the hospital right now. The*people were mostly hit by chunks of concrete, asphalt and aircraft debris*. They were *also hurt by the trampling of people getting out of the way*.

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.

Beryl fired this volley in news:j5jp91$cfr$1 @speranza.aioe.org:

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.

Richard fired this volley in news:DsydnRUvjd3ArODTnZ2dnUVZ snipped-for-privacy@earthlink.com:

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