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Larry Dixon in bad crash, thankfully OK. (2 Viewers)

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Registered member said:
So now they they are doing 330 at 1000' and breaking chassis like wishbones again, maybe they will honor the memory of dale Armstrong by taking his advice and backing these monsters down a bit.
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I had a feeling posts such this might appear, we need to go 1/8 mile, slow the cars down, Yada yada yada! How many 330 MPH Passes have we seen since the last Chassis failure?
 
Registered member said:
If the cars didnt have such a long wheelbase would it keep them from taking off like that or is it because the wing is so far back?
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I think it went airborne due to the fact that the front wing was gone (keeping the nose down) and the rear wing was acting like a huge aileron. Just a guess though.
 
there was a rash of frame failures back in late 90's? i think?....besides tony and larry at memphis, didn't head and ostrander
have similar problems with frame almost breaking near finish line, just behind roll cage?
very scary stuff when these frames fail under stress....thank goodness larry was ok and doug was not involved.
 
How about we let the experts investigate and see what they say. I'm sure there are a bunch of smart guys figuring out what happened right now. Let's all be rationale and wait and see what they say happened.
 
Registered member said:
How about we let the experts investigate and see what they say. I'm sure there are a bunch of smart guys figuring out what happened right now. Let's all be rationale and wait and see what they say happened.
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While I'm no expert in chassis design, I do have a 40 year mechanical engineering background in a machine shop. With the chassis arching up in the middle as they do, cantilever beam deflection comes to my mind. With the front wing anchoring the front end down, and the rear wing positioned behind the rear axle centerline, along with tire traction wanting to pick up the front end, it's going to arch in the middle possibly inducing metal fatigue. I'm surprised that this issue hasn't been addressed sooner by Glendora. Perhaps that why big budget teams replace pipe every year. Let's just hope it never happens again.
 
"Cantilever beam deflection"?
Arching?

It's pretty obvious from that sequence that one of the left-side main frame rails fractured first, likely as a result of force applied to the chassis as it tries to yaw. Once that happens, it's a foregone conclusion the car's structure is going experience additional failure such that it arches then breaks in half like it did. I doubt insufficient strength in the vertical plane was an issue.

What I don't understand is why some of these chassis are not stiffer in a lateral direction rather than just longitudinally. With the amount of force that is applied to them, there has to be a lot of stress on them in yaw just as there is in pitch.
 
Registered member said:
While I'm no expert in chassis design, I do have a 40 year mechanical engineering background in a machine shop. With the chassis arching up in the middle as they do, cantilever beam deflection comes to my mind. With the front wing anchoring the front end down, and the rear wing positioned behind the rear axle centerline, along with tire traction wanting to pick up the front end, it's going to arch in the middle possibly inducing metal fatigue. I'm surprised that this issue hasn't been addressed sooner by Glendora. Perhaps that why big budget teams replace pipe every year. Let's just hope it never happens again.
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What you just said is correct. But the chassis is made to flex that way.
 
Let's face facts. NHRA tech dept. Is not the NTSB. After what was left of chassis in front of the footbox ground against the wall, it could be difficult to find the point of failure. A lot of dynamics are going in here - in spite of slip joints, there is a lot of compression on bottom rails. And . . . If it is found, what does NHRA do? Increase wall thickness, add more bracing and/or eliminate slip joints . . . I sure don't know!
 
Chrome Moly is very forgiving, I would say it has a memory bank. Have worked on a chrome moly chassis before and you can remove the damage tubing and and the other which looks bent returns to original jig settings. I think one of the tubes failed by fatigue, hard to almost impossible to detect so this happening to Larry's dragster was 1 in a 1000. There are so many passes made without incident I would say the design works. Thanks to the safety improvements drivers can now walk away from incidents like this. I'm by no means an expert just my opinion.
 
yes we did have several of these failures back in 99-2000 , and what was happening then? 330mph. Spencer ran 329 at Gainesville. I do not want the track shortened, I want these motors backed down. Shortening the track was supposed to be temporary and for good reason, because it would only work until the tuners caught up and had the cars going just as fast at 1000' as they did at 1320'.
My fear is that 1/8 mi will be the next 'solution' the bonehead bean counters who really don't care about drag racing come up with.
 
There is no reason for this crap. 1/4, 300mph tops. It can be done, and the racing would be awesome. There's no reason to run these cars on the ragged edge. There are no more barriers to break. 300 was it. 350 can never happen. It's not safe. You know there are grandstands fairly close to the track on the spectator side there in gainesville. You want a part in the stands to kill someone? That already happened in Phoenix, but nothing changes. The law of diminishing returns - the quest for more performance in the nitro categories has been bumping into that law over and over again for years. Enough already.
 
Registered member said:
yes we did have several of these failures back in 99-2000 , and what was happening then? 330mph. Spencer ran 329 at Gainesville. I do not want the track shortened, I want these motors backed down. Shortening the track was supposed to be temporary and for good reason, because it would only work until the tuners caught up and had the cars going just as fast at 1000' as they did at 1320'.
My fear is that 1/8 mi will be the next 'solution' the bonehead bean counters who really don't care about drag racing come up with.
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Registered member said:
There is no reason for this crap. 1/4, 300mph tops. It can be done, and the racing would be awesome. There's no reason to run these cars on the ragged edge. There are no more barriers to break. 300 was it. 350 can never happen. It's not safe. You know there are grandstands fairly close to the track on the spectator side there in gainesville. You want a part in the stands to kill someone? That already happened in Phoenix, but nothing changes. The law of diminishing returns - the quest for more performance in the nitro categories has been bumping into that law over and over again for years. Enough already.
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Great posts, Bob. I agree. I've honestly been fine with 1000', especially since my most favorite classes still run it, but the tuners have caught up, and if they've caught up, who's to say they can't exceed what they were already running?
 
Registered member said:
Let's face facts. NHRA tech dept. Is not the NTSB. After what was left of chassis in front of the footbox ground against the wall, it could be difficult to find the point of failure. A lot of dynamics are going in here - in spite of slip joints, there is a lot of compression on bottom rails. And . . . If it is found, what does NHRA do? Increase wall thickness, add more bracing and/or eliminate slip joints . . . I sure don't know!
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I looked at all those images again and I don't see any slip joints. You sure the Hadman chassis use slipjoints?

Also, looking at the dlagonals alongside the driver. The bottoms of them don't look like they were fishmouthed then weldeded. They were just butt weleded at the bottom. That might tend to make the welds at the bottom of the diagonals weaker than the ones at the top.

Oh, yeah, I forgot to say this before, that Mark Rebilas is an awesome shooter...sheesh.
 
Registered member said:
I looked at all those images again and I don't see any slip joints. You sure the Hadman chassis use slipjoints?

Also, looking at the dlagonals alongside the driver. The bottoms of them don't look like they were fishmouthed then weldeded. They were just butt weleded at the bottom. That might tend to make the welds at the bottom of the diagonals weaker than the ones at the top.

Oh, yeah, I forgot to say this before, that Mark Rebilas is an awesome shooter...sheesh.
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Which pictures show what your talking about? I missed it or else you have x-ray vision.

Rick
 
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