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Top fuel chassis failure

Posted: 05 Oct 2020, 18:17
by flynfrog
This is pretty crazy.


Re: Top fuel chassis failure

Posted: 05 Oct 2020, 18:27
by MtthsMlw
What is she wearing? Looks like a more sophisticated HANS.

Re: Top fuel chassis failure

Posted: 05 Oct 2020, 19:41
by e36jon

Re: Top fuel chassis failure

Posted: 05 Oct 2020, 22:55
by Greg Locock
Congratulations to the designers of the safety systems. What a strange failure.

Re: Top fuel chassis failure

Posted: 05 Oct 2020, 23:29
by e36jon
It has happened before. The cars have a 300 inch wheelbase, very light steel space-frames, with mechanical loads that boggle, so it's no surprise that once in a while this is the failure mode. I could only find one reference for front wing downforce at ~700 lbs. while the rear was making 10X, at 7,000 lbs, both at 300mph. They are hitting that speed at roughly half-track, and still accelerating.

As has been stated, massive props to the NHRA and family for moving the safety standards to where they are today.

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 00:15
by Zynerji
That canopy capsule looks like it could be used in F1...🤔

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 00:43
by flynfrog
Zynerji wrote: ↑
06 Oct 2020, 00:15
That canopy capsule looks like it could be used in F1...🤔
Top fuel has a few good options. I think I posted some pictures in the halo thread a while ago.

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 17:50
by e36jon
At one point in that video the canopy seems to be partially open which seems like a fail. Maybe not? I don't know what the definition of success is for it and maybe partially open is fine...

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 18:00
by 63l8qrrfy6
I reckon somewhere in the world a chassis designer is brushing up on his bending moment calculations.

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 19:45
by 63l8qrrfy6
Just noticed the car pulls a pugachev's cobra. It goes up vertically before the parachute drag pulls it back to horizontal.

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 23:27
by strad
e36jon wrote: ↑
06 Oct 2020, 17:50
At one point in that video the canopy seems to be partially open which seems like a fail. Maybe not? I don't know what the definition of success is for it and maybe partially open is fine...
She had popped the canopy. In those instances it's really slow motion and I would say she felt like she was almost stopped and wanted to be ready to get the heck out.
The stress on the frame rails is tremendous.
Even in comp eliminator when you launch you can really feel the flex.
Events like this is why you have to have your chassis re-certified from every so often.
Excellent improvements in safety. Props to the NHRA.

Re: Top fuel chassis failure

Posted: 06 Oct 2020, 23:43
by e36jon
Maybe she did pop the canopy. I suppose anything below 200mph and within 30 degrees of horizontal must seem like standing still in her world! I love that a full minute after a sub four second run these drivers are still breathing heavy from the rush when they give their interviews. I can't even imagine.

At ~2:12 in the video, when the cockpit is almost horizontal, that's when I thought it popped. Hardly matters as she walked away, thankfully. And the canopy system has survived some much worse accidents, so it's not in doubt.

Apologies if it sounds like I am bashing on something that's saving lives...

Re: Top fuel chassis failure

Posted: 07 Oct 2020, 15:34
by PhillipM
Mudflap wrote: ↑
06 Oct 2020, 18:00
I reckon somewhere in the world a chassis designer is brushing up on his bending moment calculations.
I reckon somewhere in the world a welder is very nervous about the amount of heat he put into that upper joint :mrgreen:

Re: Top fuel chassis failure

Posted: 07 Oct 2020, 22:01
by strad
It's down to the stress not a bad weld or under engineered. I wonder if it even broke at a weld. It may have, I'd have to get a good look at the chassis. Like I said after so many runs you have to have the chassis inspected and recertified because we know it gets weakened. It's not just the downforce holding the front down when it wants to lift, which it does, but also the fact the the back end is trying to pass the front end. Flex is part of what makes it work. :wink:

Re: Top fuel chassis failure

Posted: 07 Oct 2020, 23:24
by 63l8qrrfy6
strad wrote: ↑
07 Oct 2020, 22:01
It's down to the stress not a bad weld or under engineered.
Surely it's the engineer's job to design it for the correct loads!
Stress is not an act of god.