F/C chassis integrity (1 Viewer)

[stanzig44]

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

 

[d'kid]

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

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?

 

[Harry Mannback]

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

 

[Just Paul]

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.

 

[Silly Savage]

How could it wrap around the rear end when it's still mounted on the wheel?

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

 

[.]

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!

 

[Al smith]

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.

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?

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.

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?

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 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?

 

[The Counterfeiter]

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!

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?

 

[Tom]

Bob has brought up a point concerning frame inspections. Are the teams inspecting the frames on a periodic basis? Ultrasonic or eddy current may find subsuface cracks before they become a problem.

 

[Randy]

A little off topic but still related.

I watched the video again tonight with the in-laws and our main focus was watching John in the car. My father-in-law is nearly blind but still wanted to take a look. He is related to JF's father and family which is why he was interested.

We came to the conclusion that John was in God's hands in that car.

Frame by frame shows the chassis ripping away leaving John without any protection at all from the thighs down. His legs, feet up, extend down track. Next the drivers compartment tilts back. With both his legs up in the air he hangs on as he pivots. The next motion is a twist which causes the cage to impact the ground over his right shoulder. At that point the compartment rotates down and his knee appears to make contact with the ground. About that same time the chutes catch the guard rail and snag the gate which immediately stops him from going another foot down the track.

If the chutes had not caught the gate the driver's compartment would have started a series of rolling tumbles down the track until the whole mess came to a stop which could have been as far as the sand trap. Every time the driver's compartment rolled over it would have worked his feet, legs, arms and body. I don't need to comment on what that would have done to John because it never happened.

If you have access to the video look at it again and see how close to the beginning of the disaster John stopped. I think it was a miracle.

You could sit in the back of a moving pick-up truck tossing parachutes at that gate for an hour and never get a chute to catch it like it did. But John's caught it in one try.

Thank God for miracles. I hope John is thanking Him, too.

RG

 

[James]

A little off topic but still related.

I watched the video again tonight with the in-laws and our main focus was watching John in the car. My father-in-law is nearly blind but still wanted to take a look. He is related to JF's father and family which is why he was interested.

We came to the conclusion that John was in God's hands in that car.

Frame by frame shows the chassis ripping away leaving John without any protection at all from the thighs down. His legs, feet up, extend down track. Next the drivers compartment tilts back. With both his legs up in the air he hangs on as he pivots. The next motion is a twist which causes the cage to impact the ground over his right shoulder. At that point the compartment rotates down and his knee appears to make contact with the ground. About that same time the chutes catch the guard rail and snag the gate which immediately stops him from going another foot down the track.

If the chutes had not caught the gate the driver's compartment would have started a series of rolling tumbles down the track until the whole mess came to a stop which could have been as far as the sand trap. Every time the driver's compartment rolled over it would have worked his feet, legs, arms and body. I don't need to comment on what that would have done to John because it never happened.

If you have access to the video look at it again and see how close to the beginning of the disaster John stopped. I think it was a miracle.

You could sit in the back of a moving pick-up truck tossing parachutes at that gate for an hour and never get a chute to catch it like it did. But John's caught it in one try.

Thank God for miracles. I hope John is thanking Him, too.

RG

I'm not a real religous person but having seen this I think miracle is the correct word!

 

[none]

some how frightening and reassuring at the same time.......amazing

 

[Silly Savage]

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!

Perfect example of why I think most fans are idiots.....

 

[Rexfiles]

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?

The slick (left) is clearly delaminated.

I'm really not being a arsewipe here (other places maybe, yeah)

But either ya' might wanna' see an optomotrist or trade in that 61" TV ya' got there

There is a layer of rubber missing clear off that tire.

In the vid frame by frame you can see it leave.

REX

 

[.]

Perfect example of why I think most fans are idiots.....

Why, because they claim to see things that didn't happen, like wheels locking up?

 

[turbo ken]

What gets me is that the current T/F-F/C tires are supposed to be safe to 325 mph, but it really gets me as to why goodyear decided sit on their hands under their butts when they know that a tire is needed to withstand 340+ mph. I guess their satisfied with injuring drivers every so often, and the occasional death of one.

 

[none]

I'm interested in the topic of funny car chassis safety. As a driver of an alcohol funny car, anything involving safety gets my attention - even though we go much slower than the fuel guys. I am not interested in reading posts where people take shots at each other - if you have issues with someone else on this site please send a PM. For those who thrive on watching people in conflict, turn on the news or watch a "reality" TV show.

 

[.]

What gets me is that the current T/F-F/C tires are supposed to be safe to 325 mph, but it really gets me as to why goodyear decided sit on their hands under their butts when they know that a tire is needed to withstand 340+ mph. I guess their satisfied with injuring drivers every so often, and the occasional death of one.

Did you ever consider that maybe they've done as much as is humanly possible with the materials and technology we have and now they're trying to do the impossible? I wish I could remember where I read it but somebody talked to a Goodyear engineer and when asked what tires were the biggest challenge he said it was the tires used in funny car and top fuel.

 

[Smiley]

What gets me is that the current T/F-F/C tires are supposed to be safe to 325 mph, but it really gets me as to why goodyear decided sit on their hands under their butts when they know that a tire is needed to withstand 340+ mph. I guess their satisfied with injuring drivers every so often, and the occasional death of one.

Where the MPH is an average over specific distance travelled (Point A - Point B in N seconds) can anyone tell me what the actual MPH is crossing the finish line?

I would guess that a 330MPH speed would perhaps start at 290MPH at the first MPH sensor and could perhaps be 340+ MPH at the finish line.

So, if the tires are rated to 325, are the cars far exceeding that speed at the finish line?

Or does the rev limiter stop that from happening?

 

[Usual password less 1]

Brian

It is about 1% so if you get an ET slip that says you went 327, it was going at about 330 at the finish line. The mph is an average over the last 66ft. of the 1/4 mile.

Jeff