Crush structure

[Mike Devins]

I am in the final stages of building a buck for a new FF and the owner had asked that we incorporate a crush structure into the nose. I have contacted Plascore in Zeeland, MI and they have supplied a piece of aluminum honeycomb that will be incorporated into the nose of the new car.

As a reference we had looked at both the FSAE and CHAMP Car requirements for frontal crash.

FSAE is max 20g at 23 fps (15.69 MPH)

CHAMP Car is 12 meters per second (26.88mph) with a maximum of 80g for the first 10ms - average of 40g max requirement.

We settled on Max 32 G's at 26mph.

I'll post pictures of the construction at it proceeds.

[Stan Clayton]

Mike, SCCA uses the FIA Formula 3 standard for most chassis requiring a certified nose crush structure. It calls for an impact velocity of 12 mps with an average deceleration of 25g, and all structural damage must be contained in the zone ahead of the front wheel axis.

Stan

[TimW]

FYI, Mike, SCCA uses the FIA Formula 3 standard for chassis requiring a certified nose crush structure.

But aren't the sacraficial structures now 'optional' per the 2007 GCR, or even allowed to be made from non metalic materials?

[Stan Clayton]

Tim, only chassis constructed of non-metallic composites require a front crush structure meeting the F3 criteria. As you note, for all other chassis a nose structure is optional as well as its construction. Since Mike is considering constructing his project crush structure to some standard I provided him with the standard for the type of race car he is working on (light formula car). Stan

[Billy Wight]

We settled on Max 32 G's at 26mph.

How are you qualifying your crash structure? Physical test, or calculations? If physical test, what technique are you using? Just curious, thanks-

Billy Wight

[Wren]

How are you qualifying your crash structure? Physical test, or calculations? If physical test, what technique are you using? Just curious, thanks-

Billy Wight

there is lot's of information(some of it quite funny) from the FSAE guys on how they test their front crush structures.

The simplest way is to instrument a respresentative mass and drop it on the crush structure. Measure decel and displacement and back a few numbers out.

One option I would really like to go forward with is the use of LS-Dyna(finite element deformation software) for preliminary testing.

[R. Pare]

Tim, only chassis constructed of non-metallic composites require a front crush structure meeting the F3 criteria. As you note, for all other chassis a nose structure is optional as well as its construction.

Not quite so - FF & FC still require a crush structure (assuming there wasn't something in Fasttrack that I missed!), though the performance level is not quantified. The construction requirements that are stated, are, however, not followed quite to the letter nowadays. FSCCA has to be run without modifications, so if it comes from the factory with a crush structure (don't know - never really looked!), then by definition it is required.

[Stan Clayton]

(assuming there wasn't something in Fasttrack that I missed!)

January Fastrack, page F-3.

But come to think of it, I was thinking specifically of FF/FC, which isn't exactly all other classes. I may have missed one or more.

[R. Pare]

That has to be one of the stupidest things the club has done yet!

[Stan Clayton]

You might not think so if you had seen the (IIRC) Univ. of Colorado report at last year's SAE conference. Their F-SAE team reported on the testing of a generic SCCA-spec foot box, which acted like the beer can test -- slight initial resistance followed by total collapse followed by a fatal G-spike as things went solid. The team are now working on a generic composite (honeycomb/kevlar) crush box meeting F-SAE recommended loading, which they will share openly. That performance will not directly translate to an F3-spec foot box, but it will be better than what most cars have.

There are numerous non-linearities in crush box behavior that make predicting any given installation's behavior a crap-shoot. So much so that FIA requires retesting after ANY substantive changes to either the crush box or the chassis. Anyone with an aluminum foot box on their FF/FC that has not undergone actual crash testing is gambling that the designer got lucky.

Stan

[Mike Devins]

FF does not require a certified crush structure, the rules read: "[SIZE=1]There shall be a crushable structure, securely attached to the front bulkhead, with a minimum cross section of 200 sq. cm (31 sq. in.), 40cm (15.75") forward of the clutch and brake pedals (not depressed)constructed of a minimum of eighteen (18) gauge 6061-T4 or equivalent aluminum."[/

F1000 reads: Front and rear impact attenuation structures are strongly recommended. Impact attenuation structures shall be securely attached to the entirely sprung part of the car. Attachment of any front impact attenuation structure shall not extend more than 50mm to the rear of the front bulkhead. Impact attenuation structures may be fabricated from metallic and/or composite materials.[/

FC Reads: "There shall be a crushable structure, securely attached to the front bulkhead, with a minimum cross section of 200 sq. cm (31 sq. in.), 40cm (15.75") forward of the clutch and brake pedals (not depressed)constructed of a minimum of eighteen (18) gauge 6061-T4 or equivalent aluminum.

So where does one start...... Anyway I have landed on a comprimize and would take any input that would be helpful

I figure that 32G is better that something over 80 which will result in death. We only have 14 to 16 inches to deal with so where to we go from here If anyone has a way to test this part I will be happy to build one for destructive testing.

Mike

[R. Pare]

Stan:

The issue isn't whether or not any particular design will withstand a specific crash test - I've seen way too many boxes that you would think were pathetic actually do their job well enough to prevent major frame collapse. The issue is that by not mandating that there at least be [i]an attempt[i] to provide a crush structure, the Club has now put itself in the position whereby it cannot disallow a blatantly dangerous structure! To dissallow ANY structure, and force a change to another, is giving tactic approval of an untested, and unquantified standard - exactly what the Club has publicly stated that it doesn't want to do.

"Anyone with an aluminum foot box on their FF/FC that has not undergone actual crash testing is gambling that the designer got lucky."

Anyone who believes that a spear sticking out of the front of the car is safer in a side impact that a token "beer can" structure is a fool.

And that's exactly the sort of scenario you have set up.

The fact that the Club has now lowered it's own construction safety standards, and is voluntarily, and with the publicly stated purpose of evasion of "responsibility", not making at least an attempt to assure even a token nod to industry "best practices", is grounds for gross negligence in a lawsuit sometime in the future - and it is by charging "negligence" on the part of the Club that a decent lawyer will get around the waiver.

This current crop of people in power positions in the Club are getting pretty scary.

[Mike Devins]

I am glad to see that this is of interest to someone besides me and my current customer. I do not believe that we need to mandate testing on every new chassis especially those in FB and DSR because of the "home built" nature of the classes but I would hope that we can agree on some standard for the build.

No one has commented on the values that we have targeted... any thoughts.

Mike

[Billy Wight]

there is lot's of information(some of it quite funny) from the FSAE guys on how they test their front crush structures.

The simplest way is to instrument a respresentative mass and drop it on the crush structure. Measure decel and displacement and back a few numbers out.

One option I would really like to go forward with is the use of LS-Dyna(finite element deformation software) for preliminary testing.

I was in FSAE for three years in college, and when we did the impact attenuator testing we calculated the energy absorption of decelerating 661lbs from 23ft/s to 0 at 20g’s. We then took a sample of our material and tested on a load cell to give us a stress/strain curve. From that we were able to find the ride down stress, and calculate the necessary dimensional properties to comply with the rules.

This calculation, however, is only valid for head on impacts in which the entire crush structure is in contact with the offending object. Off-axis and partial impacts are a different story…

While LS-Dyna and similar simulation programs can be very powerful, the results are highly dependent on knowing the exact properties of the crush structures material and its non-linearities as it deforms. All simulations of this type should be followed up with physical testing to validate the results (and the test probably won’t correlate with the simulation as close as you might think the first few tries).

The only correct method (in my opinion at least) to calculate the validity of the structure is through many physical tests in various situations (head on, off-axis, etc). The problem with this, though, is that it is damn expensive. Perhaps this is why crash structures are optional for certain classes in the GCR. Maybe someone could do all this work and come up with a mandated crash structure that has been tested and change the rules to require all cars use it? At least this would help ensure the safety of all competitors, but it could also open up some legal issues if someone did get hurt.

-Billy

[Stan Clayton]

The issue is that by not mandating that there at least be [i]an attempt[i] to provide a crush structure, the Club has now put itself in the position whereby it cannot disallow a blatantly dangerous structure! To dissallow ANY structure, and force a change to another, is giving tactic approval of an untested, and unquantified standard - exactly what the Club has publicly stated that it doesn't want to do.

The Club cannot disallow a blatantly dangerous structure? What are you talking about, Richard? The Club has moved away from mandating the aluminum foot box you seem to like so well precisely because it meets no accepted industry standard. The opposite extreme would be to mandate FIA-compliant noses for all cars, which the Club is not going to do, either. What the Club has done is encourage the use of a front impact attenuation structure in much the same manner that we encourage the use of a head and neck device.

Anyone who believes that a spear sticking out of the front of the car is safer in a side impact that a token "beer can" structure is a fool.

Huh?

The fact that the Club has now lowered it's own construction safety standards, and is voluntarily, and with the publicly stated purpose of evasion of "responsibility", not making at least an attempt to assure even a token nod to industry "best practices", is grounds for gross negligence in a lawsuit sometime in the future - and it is by charging "negligence" on the part of the Club that a decent lawyer will get around the waiver.

The Club's legal team disagrees. What we have done is permit much better crush boxes than were ever permitted under the old rule while eliminating our own standard which prohibited clearly better industry standards.

[Stan Clayton]

I am glad to see that this is of interest to someone besides me and my current customer. I do not believe that we need to mandate testing on every new chassis especially those in FB and DSR because of the "home built" nature of the classes but I would hope that we can agree on some standard for the build.

No one has commented on the values that we have targeted... any thoughts.

Mike

There is plenty of interest in the Club, Mike. We actually considered the FIA standards last year, but since they require crash testing of each design with the chassis it will be attached to, we ruled that out on cost grounds.

I notice you called for a maximum g-load of 32. Have you calculated the average? The F3 average of 25g allows for a max of roughly twice that, which has proven quite survivable.

Stan

[Mike Devins]

Stan,

Champ Car allows a max of 80g's for 10ms and an average of 40. Plascore is supplying the data should be here on Monday.

Thanks, Mike

[R. Pare]

The Club cannot disallow a blatantly dangerous structure? What are you talking about, Richard? The Club has moved away from mandating the aluminum foot box you seem to like so well precisely because it meets no accepted industry standard. The opposite extreme would be to mandate FIA-compliant noses for all cars, which the Club is not going to do, either. What the Club has done is encourage the use of a front impact attenuation structure in much the same manner that we encourage the use of a head and neck device.

Unbelievable!

Let's see: the old rules mandated a safety structure be present, with language that pretty much precluded a tubular construction that could easily penetrate the side of another car ( my spear scenario) whereas the new rules specificly allow a safety structure to not be present at all.

Oh yea - that's a massive improvement in safety!

Stan, the disallowing scenario can go like this:

Racer Joe damages his crush box/nosecone and replaces trackside it with a steel tube structure to hold up his wing, and caps it off with a token fiberglass and duct tape shell. The Steward disallows his running because of an "unsafe" item on his car. Racer Joe protests the Stewards actions and loses. It is now on official record that his structure is deemed "unsafe" or "dangerous" and that he has to replace it with a "suitable" component.

The very act of officially declaring an object "unsafe" or "dangerous' and then allowing an alternative is giving an official approval that the alternative is "safe" or "not dangerous".

And that alone is a "standard".

Second scenario: Same as the first, except that Racer Joe wins the protest on the grounds that that structure is not prohibited, and that there is no quantifiable "standard" by which to determine that it is "unsafe".

This ruling can now be used as a precedent-setter in any other "unsafe object on the front of the car" protests for the remainder of the year.



Now, if the Club were to specifically disallow tubular structures ahead of the footbox front bulkhead, then you would get my blessing - I lobbied for that years ago.



Anyone who believes that a spear sticking out of the front of the car is safer in a side impact that a token "beer can" structure is a fool.

Huh?

Not going to touch this one with a ten foot pole!

But I'll let you decide for yourself which type of structure you'd rather have t-bone your car : a narrow-faced triangular steel tube structure that's strong enough to withstand wing loads and can easily puncture thru the sidepanel into your gut, or an aluminium box that can spread the loads over a bigger area, and has at least a chance of not penetrating the side panels.

The Club's legal team disagrees. What we have done is permit much better crush boxes than were ever permitted under the old rule while eliminating our own standard which prohibited clearly better industry standards.

C'mon, Stan - that's pure BS. Accepted practice under the old rule allowed FIA performance-level structures, built to whatever performance standard the designer wanted to spend the money and time on - nothing in the language has ever prevented that.

Granted, the wording in the GCR did not state that composite structures were allowed (I tried twice in the early 90's to get that language in), but actual Club practice has allowed composite structures for 10 years or so, beginning with the Tatus ( with the explicit approval, though unpublished, of the Comp Board, based on the "logic" that the aluminium honeycomb satisfied the "or equivalent aluminium" rule ), with the only restriction being no carbon (still in the bodywork rules). For you to state that the Club is now somehow allowing better structures than before is rather disingenuous of you, and flat out wrong.

[Mike Devins]

with the only restriction being no carbon (still in the bodywork rules).

Richard, I beleive that the crush structure is not part of the body work and carbon is allowed.

Mike

[R. Pare]

Mike:

I'll be the first to admit that there is some ambiguity in the wording of these rules!

However, I believe that the outer shell of any crushbox structure in FF/FC - ie - that which is licked by the airstream - would most likely be ruled as having the function of "body", especially under the now-official definition in the glossary ( all of the car above the floorpan and licked by the airstream......).

The FF/FC rules governing bodywork in which the requirements for minimum crushbox structure is listed also still states that honeycomb, carbon, and kevlar are not permitted. That was supposed to have been changed in regards to crush structures about 10 years ago, and in actual practice as I pointed out previously, honeycomb and kevlar are in fact allowed and encouraged, though carbon is not (I don't know if anyone has challenged this as yet.)

You are free to use carbon if you wish, but don't be too surprised if it gets tossed in a protest - right or wrong, the groupthink of most Club techies and Stewards is that in these classes the use of carbon is verbotten in any parts of the cars - I'm talking specificly FF/FC. F1000 has some specific caveats allowing it for internal panels and in any attenuators, but it is still clearly banned from bodywork and wings.

[TimW]

The FF/FC rules governing bodywork in which the requirements for minimum crushbox structure is listed also still states that honeycomb, carbon, and kevlar are not permitted. That was supposed to have been changed in regards to crush structures about 10 years ago, and in actual practice as I pointed out previously, honeycomb and kevlar are in fact allowed and encouraged, though carbon is not (I don't know if anyone has challenged this as yet.)
.

I think this has been updated by the January fastrack with regards to composite crush boxes (9.1.1.D.6 is in the Formula Ford preparation rules under chassis/frame):

Effective 1/1/07: Change section 9.1.1.D.6.b as follows:

Front and rear impact attenuation structures are strongly recommended. Impact attenuation structures shall be securely attached to the entirely sprung part of the car. Attachment of any front impact attenuation structure shall not extend more than 50mm to the rear of the front bulkhead. Impact attenuation structures may be fabricated from metallic and/or composite materials.

[R. Pare]

Tim:

The conversation was about whether or not the new rules permit "better structures" relative to the old rules.

"Better" depends on how you define it. To me, since we are talking safety structures at the Club level, where getting out every ounce isn't always the most important objective, "better structures" in a safety item means the performance level - ie - its performance in protecting the driver - NOT just the allowed materials, where the use of carbon also allows less weight. In that strict sense, Stan is correct - the specific allowance for carbon WILL allow better structural efficiency. But, the fact that carbon is used does not automatically guarantee that the performace in a crash is going to be better than that of a non-carbon structure - to imply that it does is flat wrong.

The gist of my arguement was that while the new rules specificly allow composits, the actual practice under the old rules allowed them also, with the possible exception of carbon, and that the designer has always been free to build the structure to whatever performance level he wished, (even using only aluminium) up to, including, and even past, F3 specifications - there has NEVER been any artificially imposed limit as to what the performance level could be.

My apologies if I wasn't clear enough on that and the confusion that ensued.



On the attenuator outer skin issue, lets play "What If" for a minute.

Note that the attenuator is listed under "Chassis", and states that composits are allowed in its structure.

However, under the "Body" rules, carbon is not.

According to the Glossary, the outer skin of an attenuator, IF licked by the airstream, is considered to be bodywork - no ifs, ands, or buts about it - there are no exceptions except for components accociated with the function of the engine and/or transmission.

So the dilemma becomes this: if the outer skin of an attenuator is purely decorative and not structural, is it under the body rules or the attenuator rules?

If the outer skin of an attenuator, designed such that it is an actual structural component that contributes directly to the performance level, is made of carbon, it would be legal according to the new rules - no question about that, I would argue.

But what if the outer skin is purely decorative and has no structural value?

It is very possible that it would be deemed illegal via the bodywork rules!

Ain't figuring out these rules fun??

[TimW]

Richard:

Was not trying to advance a counter argument to the thread; rather just that the rules do allow a crushable structure to be carbon, which you said was illegal. The way I interpret the rule is that if the crushable structure is attached to the chassis and enclosed (but separate) from the nose, carbon is fine (i.e. you replace your 18ga aluminum box with a carbon one). If you attempt to make the nose piece from carbon thus its the attenuator and the bodywork, then it is not. So perhaps its not worded as crisply as that, but that is the intent or spirit of the rule when I inquired and additionally if you do build a non-bodywork enclosed structure to be the crushbox from carbon the intrepretation of it being illegal would be a stretch the way its currently worded.

Tim

[R. Pare]

Tim:

My arguement regarding carbon were, I thought anyway, in regards to the old rules. Again, my apologies if the carry-over of the train of thought was not clear.

As regards the new rules, you are correct: the attenuator structure can be made of carbon.

The potential is still whether or not a token skin bonded to the actual attenuator can be carbon or not. Most likely, the actual practice will be to think of it as an integral part of the attenuator, as long as it cannot be easily removed from the attenuator. In the case of it being an easily separatable part, you could get in trouble if someone decided to protest.

Part of the problem lies with the use of the word "attenuator", as opposed to "crushable structure". While I argued for the use of attenuator because of the intent-of-use implications, for any of us to automaticly conclude that a token outer skin, even if it is bonded to the actual attenuator, is automaticaly under the jurisdiction of the attenuator rules rather than the bodywork rules, could be an error. How likely, I don't know, but the potential is there.

The problem with the old "crushable structure" wording is that in actual fact, ANYTHING is "crushable" - including a solid block!

[LJennings]

PROPOSALS FOR 2008

3. CHASSIS


It is the intention of the Ford Motor Company Ltd to adopt new chassis regulations for 2008 onwards which meet new safety standards in line with MSA and FIA recommendations. Ford Motor Company, the MSA and the FIA are working towards a commonset of safety regulations for tubular steel single seat race cars and as soon as this investigation is complete and test the procedures confirmed we will communicate the regulations.

The test procedure will be broadly in line with current F3 chassis tests for roll structure static load tests, survival cell andfrontal protection (as per below) and side intrusion tests all modified to suit steel tubular chassis constructionsA unique front crash structure (crash box) will be mandatory and will be a single supply available from Formula Ford International.

• To test the attachments of the frontal impact absorbing structure to the survival cell, a static side load test shall be

performed on a vertical plane passing 400mm in front of the front wheel axis

• A constant transversal horizontal load of 30kN must be applied to one side of the impact absorbing structure using a pad, a pad 100mm long and 300mm high, with a maximum radius on all edges of 3mm. The centre of area of the pad must pass through the plane mentioned above and the mid point of the height of the structure at that section.

• After 30 seconds of application, no failure of the structure or of any attachment between the structure and the survival cell

• During the test the survival cell must be resting on a flat plate and secured to it solidly but not in a way that could increase the strength of the attachments being tested

• The survival cell forward of a transversal section 200mm to the rear of the front wheel axis, shall be subjected to an impact test against a solid vertical barrier placed at right angles to the centre line of the car.

• If such a part is tested separately from the rest of the survival cell it must be attached to the trolley in such a way that it does not increase the impact resistance of the structure being tested.

• For the purposes of this test, the total weight of the trolley and test structure shall be 560kg and the velocity of impact 12 metres/sec

•The resistance of the test structure must be such that during the impact the average deceleration of the trolley does not exceed 25g

• All structural damage must be contained in the zone ahead of the front wheel axis

[Stan Clayton]

What is the source of this information? (Got a link?) I read a couple of months ago that they were putting off the proposal until 2010. Stan

[LJennings]

http://www.britishformulaford.co.uk/...0Version01.pdf

Page - 17

[Stan Clayton]

Very interesting...thanks! I have a copy of their rules from April 2005 which mentions in one brief paragraph that they were considering updating their chassis rules for 2008, but then I read earlier this year that they had announced a delay of a year or two. I'll see if I can find the source of that claim. In any case, if they intend this program to be in place for next January, they need to iron out the details pronto!

A 30kN "push off" test is pretty stout (30kN is a bit over 6700 lbf). FWIW, this is the test the Swift 016a nose failed when they first tried to pass the FIA F3 tests. A redesign got them though on the second try.

Setting aside the question of mounting spears to the front of one's car (quad-fifties we can talk about, but spears are so...19th century! ), these tests can be difficult and expensive to get through. Makes me wonder if our friends across the pond are trying to weed out the smaller contructors?

Stan

[bryancohnracing]

My dad has an old bayonet from a WW1 rifle. I wonder if I can rig that sucker up.....

Stan, Serious question: Will old cars with original log books such as my 1978 Royale still get grandfathered? At some point doesn't that have to stop? I'm not sure how I'd attach a proper box to the car as the shocks, masters, rockers, and sway bar all mount in front of the front bulkhead! I'm sure I'd find a way. Save for the nose box, my car would pass a current homologation. Why not bring the masses up to at least the 90's in this way? While not one to want to spend $$$ on useless things, the CR Dept could use the funds raised from all the homologation fees to do something useful, like actual testing on crush structure's! What a concept! Maybe a discounted fee for grandfathered cars? Let the flaming begin...

FYI, I've seen a tubular nose frame "modified" with flat 1/8 inch steel (cut with a torch) welded to the tubes. This "qualified" as a crushable structure under the old rule. Nice jagged edge to slice and dice you as a leading edge.

bryan

[Stan Clayton]

Stan, Serious question: Will old cars with original log books such as my 1978 Royale still get grandfathered? At some point doesn't that have to stop? I'm not sure how I'd attach a proper box to the car as the shocks, masters, rockers, and sway bar all mount in front of the front bulkhead! I'm sure I'd find a way. Save for the nose box, my car would pass a current homologation. Why not bring the masses up to at least the 90's in this way? While not one to want to spend $$$ on useless things, the CR Dept could use the funds raised from all the homologation fees to do something useful, like actual testing on crush structure's! What a concept! Maybe a discounted fee for grandfathered cars? Let the flaming begin...

Bryan,

We have no plans to mandate certificated nose boxes (front impact attenuation structures) on tube frame cars, and certainly none for older designs. Note that the proposed UK FF regs call for a single nose supplier, who will presumably establish a front chassis design that all the FF constructors can build to, thereby assuring the mandated nose will fit and perform to specification across a wide variety of chassis marques. OTOH, AFAIK neither the Brits nor the Europeans typically demand retrofitting structural upgrades to older chassis. Every few years new rules go into effect and from then on new cars are built to the new rules, but older cars soldier on just as they do here in the States.

BTW, for us to do something like what is planned for UK FF, we too would need to go to a spec nose for all cars to make the economics work out. Given the tort climate here in the USA, can you see a company signing up to sell those nose boxes? Me neither...!

We also have no plans to arbitrarily eliminate older chassis designs. Most older cars just fade away without us having to refuse to accept them at races. Ones that do stay around tend to have immaculate care, like your car, and are virtually better than new, so there is no need to force them out. It's all good.

Stan

[Mike Devins]

Spoke to Fritz at Plascore this morning and he said that the max G load to begin the crush is approx 2X the amount that you will see during the remainder of the crush. During the balance of the stroke their testing shows approx +/- 2 percent - all of the engineering specs that they have to satisfy require +/- 5 percent. A 1/4 inch pre-crush will eliminate the initial spike.

The illutration is from the hexcel web site.

[Stan Clayton]

Good info, Mike! BTW, are the test results based on one block like that in the first photo you posted, and if so, what are its dimensions? Thanks! Stan

[Mike Devins]

Stan,

I believe that the Hexcel info in very generic and only demonstrates the "ride down" chracteristics of the material.

The block in my original posting is 12x12x24, it has a compressive strength of 750 psi after the initial pre-crush. Fritz has provided a spreadsheet that can be used to size the core based on velocity, vehicle weight and max G-force.

If anyone would like a copy email me and I will send it to you.

Mike -

hrp-llc at comcast.net

[Billy Wight]

Here's a plot of actual data from the crush structure material we used back in my FSAE days. It's a foam material, not Al honeycomb, but it shows the typical characteristics of the crush of either material:

[Roux]

Bryan,

My RP31 has been modified to have quite a long aluminum crush box. It also has rockers, masters, ARP out front. I can send pictures if you like. It is pretty tight once you integrate everything in there but I think it is way better than nothing

Steve

[Matt Conrad]

After seeing Paul Tracy's crash in practice for the Long Beach Grand Prix, the crush structure issue has been on my mind since. I've watched the impact several times and it seems to me that the carbon nose didn't really do its job and most of the energy from the crash went into the driver....resulting in a compression fracture in Tracy's back.

The impact was head on (I'm guessing maybe 70mph??) into a concrete barrier and the nose only had minimal damage to the very tip of it. I guess this situation shows how difficult it is to engineer a structure that needs to handle impacts at 200 mph....and still work effectively in slower speed impacts.

Anybody else have comments....

Matt Conrad
Phoenix Race Works, LLC

[Stan Clayton]

Matt, I didn't see Tracy's impact on TV and don't have the complete specs for ChampCar, but Mike's post from the first page of this thread lists them as 12 mps impact, permitting a max of 80 G's for 10 ms. IIRC, DoT and SAE consider frontal impacts over 60 G's for 30-40 ms to be generally fatal. If that is true, 80 G's for 10 ms seems to be skirting with the outer limits of what a person can take and be expected to survive.

FWIW, FIA impose considerably lower maximums for Formula 1. From their 2006 technical specs:

For the purposes of this test, the total weight of the trolley and test structure shall be 780kg and the velocity of impact 14.0 metres/sec. The resistance of the test structure must be such that during the impact :
- the average deceleration over the first 150mm of deformation does not exceed 5g
- the average deceleration of the trolley does not exceed 40g
- the peak deceleration in the chest of the dummy does not exceed 60g for more than a cumulative 3ms, this being the resultant of data from three axes. Furthermore, there must be no damage to the survival cell or to the mountings of the safety belts or fire extinguishers.

I imagine these specs go a long ways towards explaining the very long noses one sees on F1 cars these days. A max of 5 G's for the first 6", then averaging NMT 40 G's for the rest of the test, done at 780 kg and 14 mps. That's a lot softer touchdown than permitted in Champcar.

One more thing...if the impact was at even a small angle other than square on the concrete, all those calculations go out the window.

Stan

[Mike Devins]

http://youtube.com/watch?v=AfJbsrF4H0g

[Brands]

The injury suffered by Tracy occured when the car landed heavily, not from the initial head on ipmact. Hard landings are a problem, and with the driver sat on the floor it's hard to see what could be done to prevent this type of compression injury. The first impact was not a direct head on hit either, as the car was sliding sideways, hence not much nose damage. It's strange how drivers can walk away from huge accidents, yet the more inocuous wrecks can hurt more if the impact is transmitted to the driver in the wrong way. Dale Earnhardts wreck is a good example.

[preform resources]

I have to agree with Matt,the nose didn't dissipate the energy from such a violent hit.I'm sure that the drop to the pavement didn't do him any good either but I suspect the crush structure worked too well.
Dave Craddock