It's called a Driver's Safety Cell for a Reason!

[Canadian Formula 3 Championship]

[FONT=Verdana]I don’t want to belittle any other Formula, I didn’t join this site for that, but I do have some grave concerns for open-cockpit racecars that have tube-framed chassis’. I know many Formulas do fall into this category, but this topic is just from the driver’s safety aspect and not which car is better, mine or your’s, this or that.

[/FONT] [FONT=Verdana]First and foremost, any racer wants to be as safe as possible, that’s a given. And anyone whom jumps into the cockpit has to assume all the risks. But when that new person decides to become a racing driver, why with his sub-par skills, zero race-craft and vulnerable composure then buy a steel tube-framed, open-wheel racecar?

[/FONT] [FONT=Verdana]I myself, would be frightened honestly to be entering into a corner at 140 mph in an open tube- framed roll cage with skinny tires, because if an accident does happen these tubes would turn me into a pretzel…thus making driver extraction very difficult in a timely situation.

[/FONT] [FONT=Verdana]Here the carbon-fiber tub, or “Driver’s Safety Cell” makes all the difference in the world. Carbon tubs have been around for awhile now, Dallara first used them in 1985 for their Formula 3 program. Other Formulas and manufacturers have adopted them since. But I’m amazed that more chassis manufacturers have not since they’ve been around for 30 years now.

[/FONT] [FONT=Verdana]So if you’re new to racing, and your deciding which Formula is best for you, I think you must consider that the maximum protection for your own safety should be your utmost priority in your decision on what to buy, especially if you’re a novice. Now whether that’s a Formula BMW, Formula Renault, and Atlantic car or Formula 3, it doesn’t matter, but it must be a pivotal purchase point.

[/FONT] [FONT=Verdana]And with product pricing no longer being an issue, you can easily find good, clean, used, full carbon cars for $20,000, $30,000, $40,000 and ofcourse higher. The same prices levels that you would pay for many steel tube-framed chassis’.[/FONT]

[formulasuper]

Hey Mark, what's your opinion on aluminum monocoque chassis safety, such as the Ralt RT5?

[nulrich]

Carbon tubs are not necessarily safer than tube frame cars. It depends on the specific design and construction of each. It is certainly possible to build a tube frame car that is just as strong as a carbon tub car, although the tube frame will be heavier.

The major safety issue with tube frame cars is the lack of penetration resistance. All those open bays between tubes do not protect the driver from sharp objects (like broken wishbones) nor do they protect against penetration of the nose of another car in a T-bone type accident. Penetration resistance can be added to a tube frame car with composite panels attached to the outside of the tubes, in which case a tube frame car can be just as safe as a full tub car.

The major issue with carbon tubs is that specific inspection expertise and equipment is required after accidents, since there may be significant damage not detectable by visual inspection. Tubs are often sent back to the original manufacturer for repair and inspection or simply replaced. Aging is also an issue. There have been many examples of catastrophic failure of older carbon monocoques run in amateur and vintage racing.

Aluminum tubs combine the worse features of both construction methods, unfortunately! Aluminum sheet combined with honeycomb has very little penetration resistance, and aging is even more of a problem as bonds fail and rivets loosen. The aging issue can be addressed with regular rebuilds, but it's hard to add penetration resistance (although theoretically composite panels could be added).

Nathan

[Wren]

He may not be Lewis, but this could still be entertaining.

[iamuwere]

He may not be Lewis, but this could still be entertaining.

[starkejt]

I did not know junior members could advertise here. Mr. Carter grows more generous with each passing year.

[Canadian Formula 3 Championship]

I think everyone can see that in general a one-piece, full carbon tub IS safer than a tube frame. Sure specific designs and build matters, but in general carbon tubs are much safer.

Steel versus aluminum, first is the obvious weight difference, secondly the lack of aluminum corrosion, but steel has a large point of flexing before it can break whereas aluminum will fail faster beyond a certain point of that same degree of flexing.

So if an accident occurred with the same amount of force on both a steel and an aluminum structure built to the same strength parameters, the aluminum won't trap the driver inside the cockpit. And that is a safety factor for driver rescue attempts trackside.

nulrich touched on a good point with penetration resistance. This is very important especially with open-wheel cars, but I do disagree that simply adding composite panels to the tube frame chassis can make it just as safe as a full carbon tub.

In the construction of any structure for any purpose, a full one-piece will always be stronger than a makeshift solution of adding materials to an existing, weaker structure. There could always be the chance of the panel's mounting points failing and breaking away. And there has been very little application of these extra panels on tube frames by teams.

One other point that I disagree on, there is no "aging" factor in carbon tubs. The carbon does not loose its rigidity, stresses do not accumulate in carbon as does with metal, so there is no fatigue occurring that can lead to cracking or failures. As long as the carbon fiber weave does not reach its yield or breaking point, it will never weaken on its own.

This is a myth and was confirmed to me by a conversation with the Formula 3 manager at Dallara and confirmed a 2nd time with a friend of mine whom was the stress engineer for the McLaren Formula 1 team for 2 years before moving on to another F1 team.

[SEComposites]

We've seen some pretty scary stuff on plenty on carbon tub cars - cracks, delamination, loose inserts, even a new tub that had delaminated around the damper mounts because the laminator had failed to remove the plastic backing on one ply! Like all race cars carbon components require maintenance and regular inspection.

[nulrich]

I'm not sure what your name is, can I just call you CanForm3Champ for short?

You're obviously not an engineer. I hate to pull rank, but I have a PhD in mechanical engineering and have spent the last 25 years of my life designing structures, including steel, aluminum, and composite race car components, but also structures for outer space, the deep ocean, and aerospace. I don't know who your sources are, but I have never heard anyone I know in F1 claim structures don't age. In fact, typically F1 structures are "lifed" (replaced after a certain amount of use) specifically because of aging concerns.

Despite what you might have "heard" it is quite possible to build a steel tube frame car that is just as safe as a carbon tub car. The FIA specifically acknowledges that and has guidelines in their regulations for anti-penetration panels added to tube frame cars. Those panels provide significantly more penetration resistance than many carbon tubs, especially older carbon tubs. Add-on panels are used quite commonly to add penetration resistance, even to carbon tub cars, and there is a huge body of experience with them.

The steel tube frame car will be heavier but may actually be safer in some ways.

Your assertion that "a full one-piece" will always be stronger is just wrong.

And you clearly don't understand how aging works in steel or composites! Composite structures consist of millions of individual fibers in a resin matrix (commonly epoxy). No composite panel is perfect, so some of the fibers see more stress than others. Over time with repetitive stress (as is seen on a race track) some of these individual fibers will fail, at which point the surrounding fibers will take up the load.

If a composite structure sees enough stress over enough time, the panel will contain enough failed fibers that strength and stiffness is compromised. (Not sure if you play tennis, but players replace racquets regularly because the composite structure becomes "soft" after enough use.) Competitive race car tubs are typically designed primarily for stiffness and to minimize weight, and strength is a secondary concern (usually just enough to meet safety tests). Over time, the strength of a composite tub will decrease.

The weak point of a carbon tub can be the the bond line where the two halves are bonded together (if it is a two-piece monocoque). All adhesives experience some degradation over time, the amount is heavily dependent on factors like temperature, stress, and vibration (none of which are issues on race car, right? ). If a tub is designed for long-term use, then degradation over time will be minimal. If it is designed for the lightest possible weight and isn't expected to last very long (for example, an F3 or F1 car), the degradation can be more severe.

I would never race a vintage carbon monocoque F1 car for that very reason.

Older F3 cars might be very safe, but I doubt they are inherently safer than a modern tube frame car with composite anti-intrusion panels.

Nathan

[Canadian Formula 3 Championship]

SEC...I believe you, but cracks are a complete break away from catastrophic failure. We've all seen heavy impact of carbon tubs shattering like glass, but we all know that their breaking point is very, very high.

Carbon is still and always will be stronger and safer than steel or aluminum. All manufacturers regardless of industry know this. Your delamination you've described seems to be an obvious human error during its construction phase.

[dc]

I did not know junior members could advertise here. Mr. Carter grows more generous with each passing year.

He's not advertising anything, just enthusiastic about the cars he races and promotes. When it becomes blatant shameless self-promotion of a for-profit series, then we'll take issue with it.

Look guys, this isn't Jon Lewis in disguise. There isn't any reason to haze the guy because of someone else's failings and deception.

[SEComposites]

SEC...I believe you, but cracks are a complete break away from catastrophic failure. We've all seen heavy impact of carbon tubs shattering like glass, but we all know that their breaking point is very, very high.

I'm not quite sure what you mean here?

Nathan makes some pertinent points and if I wasn't in the middle of laminating a rear wing I would have said much the same. Cracks are certainly not a long way from a catastrophic failure in some cases.

I guess it depends on how you define ageing, but a composite part will 'age' with use as it's subjected to the rigors of racing for the reasons outlined by Nathan. I'm not trying to pick a fight - I make my living from carbon composites, its just important to understand their application as fully as possible.

[Canadian Formula 3 Championship]

[FONT=Verdana]…nice to see this show of support from Doug, I hope this isn’t a tar-and-feathering campaign. I did mention in my first post, please keep it professional. Let’s not resort to name-calling…Nathan you can call me just Mark thank you. I’m not the person you presume I am. I’m just a new forum member, you guys do accept new members don’t you? [/FONT]
[FONT=Verdana] [/FONT]
[FONT=Verdana]Nathan…ofcourse you would say all that, because you do build F2000 tube framed chassis’ and surely may be bias towards your own retail product, that’s natural. But isn’t this why we have forums anyways; “to agree to disagree” I’ll call my sources tomorrow morning, they’re in Euro time zones so it’s too late now, if they’re at a race, confirmation will have to wait until Monday.[/FONT]
[FONT=Verdana][/FONT]

[nulrich]

Hi Mark, nice to meet you.

I've designed both tube-frame and monocoque chassis. My preference completely depends on the application. Each method can result in a very safe car...the construction method is not what determines the level of driver safety.

For a club racing or low-level pro car, where the driver or non-professional crew are expected to prep and maintain the chassis, I prefer a tube frame chassis with composite anti-intrusion panels. That is the Radon Rn.10 approach which you apparently have seen.

For a F3-level car a monocoque chassis is a better choice. (It is significantly easier to design a tub car as well.) There are plenty of great features of F3 cars, you don't have to knock other cars to promote F3.

By the way, I'd love to design an F3 car and would like nothing more than to see a healthy North American F3 series.

Nathan

[Pop Chevy]

Hey Mark , question .... How many people can repair a damaged carbon tub ? And... how many people can repair a damaged tube frame chassis ??? It becomes a matter of economics for the low budget guy (me) . I would LOVE to have a F3 car, but if I wrecked it I would be done. The cost of replacement tubs is pretty high IF you can find one. And accidents do happen. my 2c's Pops

[Rick Ross]

Carbon tubs can be repaired at several facilities in the US......Algie, Crawford, etc. You should not have to replace the tub unless the damage was extensive. Any impact that would totally destroy a carbon tub would also probably destroy a tube frame.

[Canadian Formula 3 Championship]

[FONT=Verdana]Nathan...I guess this versus debate within' all motorsport circles will rage on forever because I've had this conversation with my friend and he told me that back in the old days when these carbon monocoques were first being developed, there were problems with the designs, and builds weren't done properly so it did produce some weak tubs do to the inexperience of the manufacturer in working with the new materials, but this is no longer the case for awhile now.

He told me that full carbon tubs are just as strong and as safe as they were when first built 10 or 20 years ago. And that carbon does no degenerate, nor loose strength or integrity over time. He also did say that tube framed chassis with added panels may loose their bonding strengths between the panels and the tube points because over time the tube chassis will flex and put pressures on these panel's mounting points to possibly fail or break away.

So really, I don't know what to tell you. There seems that there will always be 2-sides to this argument. I'm not going to say that you're wrong, nor that I'm wrong, only just that the debate rages on! You're obviously knowledgeable because you build your own cars, but my sources aren’t any slouches either and do know what they’re talking about. You did ask whom they were;[/FONT]

[FONT=Verdana]Mark Preston former Head of Research and Development at Arrows Grand Prix F1 team, (6 yrs), then Chief Composites Engineer and Chief Stress Analyst for structures at McLaren Formula 1 team, (2 yrs) then he was the Chief Technical Director for the Super Aguri Honda Formula 1 team, (3 yrs) now the Managing Director of Formtech Composites, (4 yrs) [/FONT]

[FONT=Verdana]I’ve also had this conversation with Jos Claes of Belgium whom is the Global Director for Dallara’s Formula 3 program awhile back whom confirmed my previous statements of full carbon tubs. If you want to call them up to verify you’re ofcourse welcome too, just mention my name they know me and they will discuss with you. So there you have it, I guess “we can agree to disagree” [/FONT]

[brownslane]

Just got back. For what it is worth, I would strongly suggest that a 20-year old carbon tub would be more difficult to verify its structural integrity and repair same when compared to a 20-year old bonded skin tube frame chassis. Mark, just as your friend advised the bonds that are required to attach panels to a tube frame chassis will fail with time...well, so do the same bonding materials used in a composite structure. Further to this, damage in a carbon composite structure is much harder to find than on a tube frame chassis.

In terms of total yield per pound a carbon structure will most often be better. But I have been working composites since I was a kid helping my old man build aircraft...and you will never convince me that carbon tubs don't degrade with time; they do.

Sure is a lot easier for me to remove the skins, rivets and "glue" from a bonded tube frame car and re-bond new skins to a refreshed tube frame. A whole lot cheaper as well. That is why a new composite tub is ten times the price of a new tube frame....I make my living building and repairing things....let me assure you the cost to repair a composite structure is in the magnitude of 10 times to similar refurbishment of welded tubes.

You also may miss the biggest challenge here; it is not whether a composite chassis will not fail, or a properly designed tube frame will.....take a look at the most dangerous part of the race car; you know, the part of highest vulnerability for the occupant.....it is the driver's head. No difference in a carbon or steel chassis if you knock your noggin!

Now if F3 cars had a closed canopy (similar to top fuel drag boats as an example) then a lot of crashes would be that much more survivable.

When was the last time anybody saw a tube frame car fold up on its occupant? I do not believe I have ever seen one with my own eyes. An example; I am restoring a Radical SR4 right now. It turned left into a concrete barrier at about 130 mph, then launched backwards across the track (several cars travelled under the car), then landed on its roll bar and barrel-rolled down the track, coming to rest on its floor..then to add insult to injury, a back marker with target fixation drove right into the side of the car.

With the exception of some bent tubes in the LH front corner which will need three side tubes and a front bulkhead, the car is absolutely straight. Total material costs, say $300 plus 25 hours of time. A similar crash in a carbon tub would have collapsed the LH front corner of the tub, necessitating a complete rebuild of the front half of the car. The repair would be in the $5,000 range for materials and autoclaving, plus time. Look at 200 hours.

Both cars in this crash would have saved the driver, both cars would have absorbed damage, absorbed a lot of energy and both cars could be salvaged. The difference is half the price of a new race car.

For my money (I'm not rich), and for a car that will not exceed the 150 mph threshold, a tube frame car is much cheaper, easier for the amateur to maintain, will be safe and reliable. And let me assure you, properly attached composite skins over steel tubes will
be extremely effective. Earlier this year a friend had a tire failure at T8 at Mosport...he nailed the tire wall at 120 and the left side suspension tore free...both the upper and lower a-arms tried to skewer my friend....the mandated laminated panels absorbed the intrusion and saved my friends ankle and thigh. The rules preclude bonding of the panels (so not to create a semi-monocoque) so they were just riveted on (good quality rivets)....the structure did an awesome job. In a composite tub, there would have been outer skin penetration for sure, requiring a tub repair $$$$...instead we just riveted new comp panels in place and the car was as good as new.

We worked about 60 man hours and had the car back on track the next day and on the podium on Sunday. Would not have been racing again that weekend with a comp tub..that is why we all had to carry a spare tub back in Lites...'cause it was easier, faster and safer to build a new one rather than try and fix a broken one at the track.

And I would definitely LOVE Mike Scully's F3...but I just don't have the coin! So back to my beer budget and steel tubes!

[nulrich]

Mark:

I think you misunderstand me. I'm not claiming tube frames are safer than carbon fiber monocoques--that would be as incorrect as you claiming monocoques are safer than tube frames! Each can be designed to an equivalent level of safety (although the tube frame will be heavier).

I do not doubt the expertise of your friends, but I think you must have misunderstood them. You might email them, include this post, and ask them to clarify. Every competent structural engineer knows that aging (or fatigue, to use the engineering term) is an issue with all structures, including composite structures. It's a hot topic in aerospace with the increased use of composites in aircraft like the Boeing 787, and I have a stack of academic papers to prove it. There is even specialized FEA software (made by a company called Firehole Technologies) that allow you to predict how composite strength and stiffness degrade over time in service.

To quote from one excellent source, the book Fatigue in Composites by Bryan Harris:

It is now well established that fibre composites, like metals, exhibit a form of degradation in service that can be described as 'fatigue.' A simplistic description of the phenemenon is that under cyclic loading conditions, the load-bearing capacity of the material falls with time and this results in failures at stress levels which are often well below the ordinary (monotonic) engineering strength. The mechanisms by which this deterioration occurs in composites are quite different from, and much more complicated than, those which are responsible for fatigue phenomena in metals.

At low levels of stress in monotonic loading, or early in life during cyclic loading, most types of composites sustain damage. This damage is distributed throughout the stressed region, and although it does not immediately reduce the strength of the composite, it often reduces the stiffness...Later in life the amount of damage accumulated in some region of the composite may be so great that the residual load-bearing capacity of the composite in that region falls to the level of the maximum stress in the fatigue cycle and failure ensues.

This is not just an academic discussion, there is a fair bit of evidence that the crash of American Airlines Flight 587 was the result of fatigue failure of the composite tail fin structure.

The issue for racers is that composite structures do not age (fatigue) in the same way as metallic structures. It is common for welded tube frames to show cracking in highly stressed areas long before catastrophic failure. In contrast, a composite structure may show absolutely no signs of reduced strength as it ages. That is one reason strict lifing programs are in place at every F1 team.

I agree that bond failure can be an issue when composite panels are bonded to metal structures (although differential thermal expansion is more likely the cause than "flexing" of the metal). Of course, that's not an issue with the Radon design, since the composite panels are mechanically fastened to the frame, not bonded. If damage is sustained or suspected, or simply after a certain amount of time, a panel can be removed and replaced in just a few minutes at a very modest cost. Similar servicing is just not possible with a composite monocoque.

There is absolutely nothing wrong with composite monocoques, and they have their place. However, they are not inherently safer than tube frame structures and, in my opinion, they are most appropriate for professional teams and series.

Nathan

[Zambo]

I've got to admit, this is absolutely one of the most interesting discussions that I have ever seen on Apexspeed. Tube frame, carbon tub; who gives a hoot. Keep on supporting your respective positions gentlemen.

Zambo

[nulrich]

To follow up on Tom's post, an Radon Rn.10 crashed heavily into a tire wall at over 100 mph at Lime Rock earlier this year. The forces developed in a crash like that are scary: I can show you a rod end with the ball pulled completely out and 5/16 NAS bolt that sheared through completely. The wishbones folded up exactly as you'd hope but the jagged ends pushed through the bodywork with a substantial amount of force. They were stopped completely by the carbon side panels (which include a lot more carbon fiber and Innegra than the skins of most carbon monocoques).

We had the car stripped down and mostly rebuilt later that day. If we'd had a spare steering rack we would have put the car back on track the next morning. The driver sustained no injuries, not even bruising.

Once we had the car back in the shop we carefully inspected the tube frame for damage and straightness, replaced a few parts, including some of the carbon parts, and put it back together in just a few hours. If it had been a carbon monocoque it would have taken much longer and cost much more (if it was repairable at all).

Don't get me wrong, if I were designing a car for a professional racing series where budgets are substantial I would absolutely choose a carbon monocoque. I should also point out that most of the safety advances in formula car racing occur at the upper levels, where only full carbon tubs are used, so they tend to be designed to a higher standard of safety.

Just my experience.

Nathan

[brownslane]

I've got to admit, this is absolutely one of the most interesting discussions that I have ever seen on Apexspeed. Tube frame, carbon tub; who gives a hoot. Keep on supporting your respective positions gentlemen.

Zambo

Would you rather go back to the knitting channel? Is it "knit one, pearl two" or "the hazards of dropping a stitch" ? Are they missing you there?

Have a great weekend!

T

[Canadian Formula 3 Championship]

There is no question to brownslane thread, the cost of repair is much higher for carbon tubs, you have no objection from me there, my only position was in terms of structural strength.

But we should continue on with a Car Running Cost of Budget Weekend posting one day here, you'll be surprised that Formula 3 is not as expensive to run as many people would think.

[Kazis31]

Let's make a voting pole out of this tread Apex Speed style.
If money wouldn't be an object :
Tube frame or tub?
Which one would be safer(let's not forget that there should also be progress in racing engineering...There are still some dudes bitching and moaning about fuel injection vs carburetors)It would be real cheap living in caves and beating dinner down with a stick as well.
I cast my vote for Carbon tub (therefore progress)

Cheers.

Let's turn this puppie up a notch.

[turnbaugh]

Unlimited budget?

Strong CF tub with Kevlar reinforcement. I would have the tub replaced every 5 years. I would also be driving an R18 too!

[iamuwere]

Let's make a voting pole out of this tread Apex Speed style.
If money wouldn't be an object :
Tube frame or tub?
Which one would be safer(let's not forget that there should also be progress in racing engineering...There are still some dudes bitching and moaning about fuel injection vs carburetors)It would be real cheap living in caves and beating dinner down with a stick as well.
I cast my vote for Carbon tub (therefore progress)

Cheers.

Let's turn this puppie up a notch.

This isn't the question.

This whole thing started with the following accusations:

when that new person decides to become a racing driver, why with his sub-par skills, zero race-craft and vulnerable composure then buy a steel tube-framed, open-wheel racecar?

I myself, would be frightened honestly to be entering into a corner at 140 mph in an open tube- framed roll cage with skinny tires, because if an accident does happen these tubes would turn me into a pretzel…thus making driver extraction very difficult in a timely situation.

This is the part that some very stout engineers and designers are taking issue with. As we all should as things like this spread misinformation. Secondly, I don't want a NEW driver thinking the only thing to be in is a carbon tub car which would be WILDLY too fast to be safe in.

jim

[nulrich]

This is an example of a carbon monocoque that wasn't especially safe. It's a 1999 Ferrari F1 car crashed during the Monterey Historics in 2004 (I believe). I don't know if it's possible for a tube frame chassis to get in such bad condition that it could break in half without very obvious signs of deterioration.

[a. pettipas]

gnarly

[Brands]

This is an example of a carbon monocoque that wasn't especially safe. It's a 1999 Ferrari F1 car crashed during the Monterey Historics in 2004 (I believe). I don't know if it's possible for a tube frame chassis to get in such bad condition that it could break in half without very obvious signs of deterioration.

I've often wondered about this accident and the history of that chassis. Very strange given the lack of damage to the front part. Almost like it was a show car that somehow got onto the track. Or Schumachers car he broke his leg in at Silverstone. That had pretty major front end damage. Might even have failed at the same point.

[KenT]

i read something about that chassis just after this happened. Apparently that chassis experienced a shunt and was repaired which was one reason for the failure. Another is that of all racecars, F1 cars expecially of recent vintage are built for a very finite life. They need to pass the required FIA testing and be stiff for whatever amount of races the teams budget will allow for replacement. The years of using the same chassis for years or even a full year are long gone.

[Brands]

i read something about that chassis just after this happened. Apparently that chassis experienced a shunt and was repaired which was one reason for the failure. Another is that of all racecars, F1 cars expecially of recent vintage are built for a very finite life. They need to pass the required FIA testing and be stiff for whatever amount of races the teams budget will allow for replacement. The years of using the same chassis for years or even a full year are long gone.

That's true. At Williams one year we built a qualifying only car. It had a lighter layup, smaller rads, sidepods and a monster 950+bhp BMW engine. Ridiculous really. The car made its debut at Spa and was given to Ralf Schumacher much to JPM's dismay. Perhaps that gave Monty the little bit extra that helped him out qualify the qually car! I don't think that chassis was used again. Crazy looking back on it.

[KenT]

If someone gave me a recent vintage F1 roller(not that they would) I would bring in a crew to upgrade the structure of the ceiling in the family room and mount it 14 feet above my head to enjoy it every day. On second thought, maybe it should go in the bedroom. I am sure the wife would love it.

[Marty Nygard]

Last week I was able to tour a race car repair/salvage/restore business. At least 40 cars ranging from a nice CSR Ralt RT5 to a ten liter Can Am car clone and including many Indy cars. Not to mention the boxes and boxes of spare parts, body parts, undertrays, etc. Anyway, several of the cars were being cleaned up to be sold as "wall hangers" or other show car types. Too bad I don't have room for that form of Art in my house.
Marty

[KenT]

I might have the room, but not over 50% voting rights.

[Canadian Formula 3 Championship]

I read somewhere that Kroymans couldn't fit in the car because he's a tall guy and they somehow extended the tub for him which might be the reason why the tub had such a clean break. Normally the break would have been varied size jagged edges. It's reported that this wasn't Schumacher's Silverstone shunted chassis.

[Tom Valet]

Can someone explain to me what I am seeing in the photos that Nathan posted. As originally designed, was the nose section that broke off constructed as an integral part of the monocoque? Or was the nose originally constructed separately and then attached to the monocoque (with what? Glue?) ?

The reason I ask is because that is a really clean break and if the nose was constructed separately to be attached to the monocoque, doesnt that defeat the entire purpose of having a carbon tub, ie it is a self-contained safety cell that wont break apart?

[dc]

Every carbon tub that I have ever seen was not made in module chunks as it appears that one was (even in repair). Kinda defeats the whole point of a carbon monocoque, no?

All construction types have their pluses and minuses. Right now, the only reason all club cars aren't carbon is cost—it's WAY cheaper to make a tube chassis car. Given the choice with all things being equal, wouldn't most of us rather get behind the wheel of a car properly made entirely of carbon fiber?

[turnbaugh]

What about a tube chassis with CF panels on the outside of the tubes? Seems like that would be a good hybrid combination.

Some of the added protection of the "tub" features but not the high cost, plus it would still be repairable.

[brownslane]

What about a tube chassis with CF panels on the outside of the tubes? Seems like that would be a good hybrid combination.

Some of the added protection of the "tub" features but not the high cost, plus it would still be repairable.

Dean, you have hit the nail on the head. Bonded skins over a tube frame construction can achieve higher strength, lighter weight and greater safety (especially if you use kevlar or other intrusion-resistant aramids). The extra strength of bonded/riveted floor pans (in alloy, typically) have already been proven everywhere. My CSR has just these side panels. They are bonded and riveted. They look cool as well

[nulrich]

The section that broke off was part of the original monocoque. It should not have failed like that under any circumstances. I'm told this car was purchased from Ferrari and the purchase agreement required that car be prepped and maintained by Ferrari personnel. I think it is extremely unlikely it was modified as Mark suggests but I suppose anything is possible.

I found a quote from Ross Brawn about the failure:

We have got the car back at the factory and we are looking at it. Although it’s the same model as the one Michael had his accident in [at Silverstone in 1999], it’s a very different sort of accident. In Michael’s he had a front impact and the wheel came back into the cockpit and that’s what broke his leg. With this one – as far as I understand – the car went backwards into a barrier and the wheel became stuck in the barrier as the car spun around it, putting a tensile load on the car.

I believe all F1 tubs are constructed in multiple sections and bonded together (if there are one-piece monocoques I've never heard of them or seen any). In 1999 I'm not sure what the fashion was, but the Ferrari tub could have been made from front and rear halves. I know the BAR tub was split vertically around the steering wheel. Most current F1 tubs are constructed from at least four separate moldings, and I believe the most popular approach is to split the tub into upper and lower halves closing over internally bonded composite bulkheads. I wouldn't be surprised if some of the teams are using more innovative approaches but not disclosing the details!

It does look like a bond failure rather than failure of structural plies. F1 monocoques are not constructed for longevity, they are designed to provide the stiffest and lightest structure possible and are tested structurally in only a few discrete points.

Nathan