So guys let me just ask you stright up is heat treating fuel cars safe and good for our sport? Thanks in advance

Jim,
the left slick on Force's car chunked and set up a vibration/oscillation that fractured the frame. There was no debris from Bernstein's or or parts falling off John's car contributing to the failure. It was the same type of harmonic that Eric Medlen's car went through but this time they had the "black box" recorder to better analyse what happened.

NOW!!!! READ MY LIPS. The tubing was not heat treated to the point of being brittle. The process is a slight modification of the 4130N specification and is performed mainly to tighten up the variation between batches of tubing with the added benefit of adding a little strength. The variaton between various batches of tubing as supplied by the manufacturers is greater than the increase that results from the heat treating.
FEA analysis of the Force deal indicates that the frame would have failed with regular 4130N, mild steel or even if the tubes were .120 wall (more than double the actual thickness). The FEA analysis included the use of the vibration module which is the key to this whole deal--the car shook apart.
All of the "reliable sources" are talking out of their arses if they have not been closely involved with the whole deal. I checked the link that Randy Goodwin posted last night and even called the guy involved as have John Medlen, Jim Head, Rob Flynn and several others. He is not a race car engineer and admits that. I am afraid that I was not impressed with his grasp of race car dynamics as is quite often the case when "civil" engineers get involved in this sport.
I don't profess to be qualified either but I have been around this sport for over 40 years and have seen the non race car qualified engineers come and go but the basic designs never change. The builders like Hadman, Plueger, McKinney, Long, etc know what works from being intensely involved for a long time but at the current performance and stress levels we are getting into the twilight zone in some areas. Aircraft design reached that plateau a long time ago and it would be incromprehensible to design a plane subject to the kind of loadings that fuel car undergoes without the aid of a computer.

Roo

I HAVE NOTICED THE SAME THING MIKE, EVEN CHANGING OUT WHAT I THOUGHT WAS A CONTAMINATED BOTTLE OF ARGON. CLEANING THE CRAP OUT OF THE TUBING DIDN'T HELP. SOME OF THE TUBING IS JUST NOT AS PURE AS IT USED TO BE IT SEEMS LIKE.

RICK

Roo, If a chassis has been built a certain way for many years and is still built the same way with the only difference being heat treated tubing and we have 2 catastropic failures in 6 months couldn't this be the problem? BTW I read your lips and I don't think the heat treating makes the tubing brittle I think it is welding it afterwards that does it......as I have been told.

New Here.
Couple things, Just wanted to say that I'm happy J.F. is going to be alright after last weekends event. He is truly an amazing person, the guy is seriously hardcore.

Just bought my first Funny Car and hopefully we might get some runs in later this year, (It was easier to buy the car than to try and land a seat) and after reading the great information posted on this thread regarding Chassis integrity I was curious if testing a Fuel Chassis "Foam Filled" would be worth taking a look at???? Would it soothe out some of the Harmonic's in the frame and still allow some flex in the chassis? Has onyone ever gave it a try?

Keith,
the change in the tubing is well within the window of weldability and that is not the problem. In both cases the Force cars went thorugh a period of intense vibration due to tire damage. In most of the prior incidents related to tire failure (Bazemore at E'town for example) the majority of the tire came off the car very quickly and the high frequency vibrations dd not occur.

Roo

Keith assuming that what you say is true [and I do agree personally] the question then becomes is it practical and/or possible to build a chassis capable of withstanding this type vibration?????

If taken one step further, if it is NOT practicable what conditions have to change to bring us back to a state where the tires are not coming apart? Is Romine correct in removing down force?

thanks
jim

If the vibration is the reason the chassis failed and was caused by the tire chunking, ultimately, wouldn't the tire be at fault? Once again it looks like it all goes back to the tires.
To me, it seems that the recent emphasis on “fixing” the chassis is because the race teams and chassis builders can independently “fix” the chassis, whereas it appears they (race teams, NHRA) can't wait any longer for Goodyear to provide a safer tire.

-stan

One more Question. How does this relate to the "long cars"... Are we seeing the same type of flex/cracked rail in the event of chunking? And how would this relate to Hillary in February? Also, because the driver is not sitting in the pivot point, but is 60 or so inches ahead of the axle, are the rails flexing enough to protect the driver from the lateral gee loadings?

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As some one that knows very little about this subject I have a question. Is there a chassis dyno or some sort of device that can replicate what a chassis goes through in cases like this?

While I’m asking questions, if the tubing is breaking near or at the weld (again I don’t know) is there a better way assemble a chassis (without welding)? Just wondering…

This has been a very interesting thread.

Dan

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Eddie Hill had the same thing happen back in 1997 at Sears Point, tires came apart and folded up the chassis front to rear without hitting anything. It broke behind the motor and in front of the foot box almost instantly with no impact of any sort.

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Did you miss the part wear the tire delaminated and went through the body?

No. Did you miss the part that the wheels didn't lock up? Watch the video again and again since you obviously are missing it or seeing something that didn't happen. The wheels did not lock up!

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Why would tire vibration fracture the frame forward of the cage hoop? And why would it not instead tear out the upright the housing is mounted to? including the anti rotation mount? Did it break at a cluster? if FEA shows that it would have broken regardless of wall thickness. Is that not saying there is no safe car in existence? I still do not understand if it was tire vibration alone why has it not happened more often? And why is it so severe this season in the Force camp? How are their chassis different from all the others? Is it possible the tire carcass itself came apart and slammed down across the upper frame rails and blew through the bottom as well? if .120 wall wont do it what about two sleeved .058 wall? would not the inner tube be isolated from the heat affected areas? How about uprights welded to saddles to minimize heat affected clusters and then the saddle plug welded and stitch welded to the mains?
How about a tube sistered immediately below the main hoop between two uprights in that area?


Thoughts?

Yes, watch the video again. Take a close look at Safety Safari rolling the cage over to extract John. I'm seeing slicks that are not delaminated. But, I could be blind. Did anyone else see this?

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