Carbon fiber body panels (much, much more) (archive)

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While I don't own a Jag, I do own a BMW (soon to be 2) and after an email from Alan, I think that you XK8/XKR owners may be interested as well.

Bear in mind, this post was cut and pasted from several posts on a BMW forum, so forgive the bavarian references and non sequiturs.

If you have any questions, please email me, as I don't visit this forum often.
(oh, and a link to the whole thread is at the bottom of this post)

If anyone is REALLY interested in trimming down the E46, or any BMW for that matter, I have some good news (maybe)

I own a aerospace prototyping company that speciallizes in building composite replacement parts to replace metal ones (sound
interesting yet?)

I just talked to our chief composites guru, and I think we can make carbon fiber (I'm talking REAL carbon here, not just a
carbon-look) body panels for not that much $.

On a preliminary estimate, we can do a CF hood (with reinforcements, mounting brackets, etc) that will be (accurate to within
much less than a mm) a true replacement for the E46M3 hood. Trunk lid should be just as easy...
side panels are a little tougher, as are outer door panels, but do-able (according to our guy).

To put this in perspective, the M3 hood (made out of aluminum for the E46) weighs at least 15kg (that is a conservative guess
based on a 2mm thick sheet of aluminum alloy the size of the hood), with the reinforcements on the back, probably closer to
20kg. The CF replacement would drop about 10+kg off of that, and would be 2-5 times stiffer (you couldn't bend it, even if
you tried)

Replacing doors, fenders, hood and trunk would run you about $3000 and would drop 100kg or so.

Now, think about it this way. Decreasing the dry weight of the car by 100kg (or more, this is conservative) is the same as
increasing the accelerative force by 7-10% at any rpm. For an E36M3, that would involve (using Dinan for example), adding
the Stg 4 Dinan setup for ~2400 (with labor, roughly). so the two are pretty close in terms of price.

Not to mention the handling improvement.
Even better, think about it this way if you did a stg 4 Dinan setup, AND the CF panels, that would give you the "equivalent" of
a non-lightweighted M3 with ~290ft-lbs of peak torque, or only 4% different from the supercharged E36M3! (for $5500, so
cheaper than the SC too....)

Just food for thought.
According to my people it won't be that hard, so I am going to guinea pig my E46 when it comes in, and we'll see what
happens....

We could do this for E36's right now, or any other model you want, the setup costs with our process aren't that great, so if 10
people wanted the same part, that would be enough for us to do it....Just to get your minds churning

Someone asked if it would make the car stealth so...

CF by itself isn't very radar absorbant, the resin is a nice dielectric reflector, in order to get good stealth you would need bare
fiber on the surface...ugh...however, it would be near trivial to mix some ferrite or schiff salts in with the resin and
paint/clearcoat (personally, my Carbon Black M3 would look kick ass with clear coated natural carbon parts...carbon/carbon
black
...oops, got to run, more later

Ok, I just got off the phone with Seth (our guru) and he says mixing RAM materials (ferrites, etc) in with the resin wouldn't be
that tough, so you in theory COULD have a stealth BMW, but at that point you would need to do WAY more than just the
body panels (headlight covers, windshield, etc etc)

And a more important note, I think that (while it may be counter productive from a weight standpoint) an underbelly venturi
plate would be quite interesting.... a whole body plate with reasonable strength would mass 10-15kg, so it wouldn't be that
bad.

we are talking to our suppliers and subcontractors right now (our carbon guru likes this idea alot), and we have two production
levels, <5 parts and 10-50 parts. If you were the only one who wanted that specific part, it might be 1000+, but if 5 of you
did, then it would be in the 700 range, if we could sell 10+ it would be in the 500-600 range. it also depends on how rugged
you want it to be, or if you want any custom stuff...
if you want to only use it for racing, we can make it REALLY light, but you may have Dzuz fasteners holding it down. if you
want it to be as rugged (or more actually) than the stock hood, but be natural carbon, it would be "like" the prices I just said, if
you wanted it with an easily paintable surface finish, it may be 100-200 more.

Bear in mind these are all VERY preliminary numbers, but we should have more info soon. Our guy is flying out to LA to talk
to one of our major suppliers, and if they respond positively, we could tool up quite quickly if we get orders.

Also, as an important note, these panels would not be DOT tested, and as such would be "for off road use only" However,
since the crashworthiness of the vehicle is only minimally effected by the non-frame panels, the only real worry I have is the
panel fragmenting on impact, but I think we can design it to pulverize enough to minimize any dangerous splinters.

We could do custom mods to the panels (wider flares, etc) but then you get back to the tooling cost...if enough people wanted
big flares, and NACA ducts on the hood, then the cost would come down. Also, an important note, the rear quarter panels are
MUCH harder to do than the fronts, as they are much more integral to the vehicle structure, so if you wanted more flaring all
around, the rear would cost a bunch more

I hope this helps, I'm putting the spurs to our guys to get more info to you guys...

And some random other thoughts:

actually, 5kg is the hood panel itself, the brackets and those grills alone probably weight that much. However, its the weight
difference that matters most, so I think we can achieve pretty good numbers. The reason most places charge an arm and a
leg...well, I can't actually tell you that, but lets put it this way, we built the frame for a unmanned aerial vehicle that is about
75cm long for $1500....the interesting part is the thing is fired out of an artillery cannon and has to withstand 16,000g's! (at that
acceleration the little model airplane propeller "weighs" almost 200lbs!

Now, if you are at all interested, or even intrigued, drop me an email, say what type of car (year/make/model) and which panels (removable ones are preferable, as panels that form part of the unibody are nearly impossible to replace with CF) you may like, or any questions you may have

Thank you for the bandwidth, and I hope you all are as intrigued as the www.bimmer.org crowd

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