GP-5 goes down at Reno. Pilot killed

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BBerson

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*facepalm*

In flight break up doesn't kill you.... the acceleration of hitting the ground does.

There is no such thing as "decelleration" BTW
I think the pilot was killed instantly inflight by air loads (accelerations)long before he hit.
But that's all I will say about the pilot in respect to the family. Nor will I discuss this nonsense about "acceleration"here again.

My interest is the engineering of the structure and why it failed.
 

BBerson

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Behel flew in the 2010 Reno Air Races when his GP-5 plane, “Sweet Dreams,” had mechanical troubles mid-flight. He was able to land safely then.
NTSB said a portion of the right wing separated.
Was that wing repaired from a previous incident?
 

BJC

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See post #7.

As I understand it, the repairs were made by the designer builder. Can anyone confirm that?

I am not suggesting a cause, but I can imagine some damage (in any airplane that has made a forced landing) that would be very difficult to detect.
 

Steve C

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From what I've heard, flutter is what took the plane down. It sounds like one of the counter balance weights may have come loose from the aileron.

I was around the plane quite a bit before Lee bought it. I thought it could have used more wing ribs and had my doubts about wood being strong enough, but it seems that had little or nothing to do with the failure. Flutter at 370 mph is something not many airplanes survive no matter what they are made out of.
 

Toobuilder

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If aileron flutter is the cause, and people point to wood as undesirable as a construction medium, take a look at the ailerons on a F4U Corsair. They're made of wood... In large part to cure an aileron flutter issue with that airplane.
 

autoreply

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What matters for flutter is stiffness per pound of weight. Typical wood (spruce, balsa) is on par with both steel and alu and only superseded by carbon.

As toobuilder alludes, wood has a huge advantage and can result in much lighter control surfaces. Why? Most aircraft parts are sized for stiffness/counter buckling. Figure of merit is stiffness over density cubed. Wood is orders of magnitude better as most other materials there. Lighter control surfaces obviously means less relative weight in the controls, meaning less balancing weight etc. Lighter controls (relatively) also are great for flutter.

A great weight avalanche if you can ride it out.
 

Aviator168

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Lighter control surfaces obviously means less relative weight in the controls, meaning less balancing weight etc.Lighter controls (relatively) also are great for flutter.


This means it would be accelerated easily (rotational wise) and takes longer to converge(good for flutter). Yes?
 

Jimstix

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I suspect that it is really the first derivative of acceleration that does the damage. Anybody know the term?
The first derivative of acceleration is called "jerk" in the US and "jolt" in the UK. Think of it as the rate of change of acceleration.
 

BBerson

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What matters for flutter is stiffness per pound of weight. Typical wood (spruce, balsa) is on par with both steel and alu and only superseded by carbon.

As toobuilder alludes, wood has a huge advantage and can result in much lighter control surfaces. Why? Most aircraft parts are sized for stiffness/counter buckling. Figure of merit is stiffness over density cubed. Wood is orders of magnitude better as most other materials there. Lighter control surfaces obviously means less relative weight in the controls, meaning less balancing weight etc. Lighter controls (relatively) also are great for flutter.

A great weight avalanche if you can ride it out.
So a wing built of balsa is superior or on par with steel and aluminum?
 

Speedboat100

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If aileron flutter is the cause, and people point to wood as undesirable as a construction medium, take a look at the ailerons on a F4U Corsair. They're made of wood... In large part to cure an aileron flutter issue with that airplane.
I would say the wing was ill suited for air racing at high speeds. Brewster Buffalo had Vne of 620 km/h. One of our aces was able to increase the dihedral of one specimen at a tight turn ( high G-load ). It had similarly tapering wing.

F8F-2 OTOH has a good plan form.

1024px-Grumman_F8F-2_Bearcat_BuAer_drawings_1949.png

Also the NACA 23015,6 wing root foil thinner than 23018 of the Brewster.

https://m-selig.ae.illinois.edu/ads/aircraft.html
 
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BJC

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I would say the wing was ill suited for air racing at high speeds.
I’m not certain just what about the wing made it “ill suited for air racing at high speeds”, but the NTSB concluded:
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The failure of the right wing under normal race loads due to an improper repair of the right wing spar that reduced its structural strength following a previous landing accident.

BJC
 

blane.c

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I don't think any conclusions ought to be drawn yet as to the cause of the crash. Lots of slow airplanes have lost wings, too - including the one in the HBX Crash Analysis thread. There's nothing "different" about speed, provided you've designed properly for it.

Speed doesn't kill. Sudden deceleration kills.
A pilot I respect very much told me "speed is not your friend".
 

Victor Bravo

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A pilot who I greatly respected (for a time) told me "We had a saying in TAC... Speed is Life".

Speed is like food, water, fire, money, sex, rules, politics, and government. There is such a thing as too little, and there is such a thing as too much.
 
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