New carbon fibre wheels

[WhiteBlue]

http://blogs.insideline.com/straightlin ... wheel.html
What do we think about this new product? I thought the Porsche and the McLaren look really cool with them.

[Jersey Tom]

Reminds me of FSAE.

Cool visually though, for sure.

[flyboy2160]

i like them except for one design detail: the integral aluminum plate.

i can't see the images on the patent application (which is primarily a manufacturing method). but the wording says the wheel uses 2 pieces of dry preform cured in an RTM mold that has the mold portion inside the rim and in back of the spokes made from a flexible material.

even though there are two pieces of preform, i suspect the fibers must be continuous across the spoke to rim joint. i'd love to see the layup, but i suspect it's highly proprietary.

even though the edmund's website said that thermal tests were done, my concern is the integral aluminum backing plate. there is a very high (for composites) CTE mismatch between the fibers and the aluminum. i'd be worried about the thermal loads in a high temperature racing application. i hope i'm wrong. but they could always change that plate to a closer CTE match if they have problems.

[Tim.Wright]

Reminds me of FSAE.

Cool visually though, for sure.

Haha after FSAE, I would never ride in a car with carbon wheels.

I believe its used on the Shelby SSC. They seem to be doing a good job.

Tim

[Nando]

19x12 - 17.8 pounds - Carbon wheel
19x12 - 19.7 pounds - BBS FI (i think they are the lightest wheels BBS makes for road use)

Almost a kilo difference, pretty impressive.

[marcush.]

Did it done it..Tom ..please FSAE is not the centre of the world...
CF wheels are a reality in Bikes for a long time and bladder type inside molds are not new to the world either.
The wheel does not look very much like it was designed for CF with all those hard edges .
OCP in Switzerland did produce CF wheels for Kawasaki already in 2005..
http://www.aero-consultants.ch/_files/d ... oducts.pdf

[Jersey Tom]

Did it done it..Tom ..please FSAE is not the centre of the world...

No kidding. It's the center of half-engineering half-handwaving decisions along with dubious manufacturing and car setup. Just saying, that's what it makes me think of. I recall seeing student built CFRP rims in ~2004-05 which resulted in some ooh's and aah's.

CF wheels are a reality [...] for a long time and bladder type inside molds are not new to the world either.

That's fundamentally my point.

In any event the hard edges don't put me off. C-channel is a good, stiff, structural shape. Underneath the (purely aesthetic) weave exterior layer I imagine all the uni is along the axis of the spokes, and also circumferential around the rim, so conforming to those profiles may be a non issue.

[ajdavison2]

http://www.sscnorthamerica.com/tuatara.php been around for a long time

[flyboy2160]

....The wheel does not look very much like it was designed for CF with all those hard edges ....

m,

i know this sounds counter intuitive, but at a right angle transition in a carbon fiber joint - say in an aircraft stiffener or here between the spokes and the rim - a very sharp corner is better.

look at this composite Z stringer from Fokker:


and this blade stiffener:


(if you're bonding or cocuring to the skin,you still want feather out the edge of the footer on the skin, as you can sort of see in the blade photo.)

i've seen the actual pull tests to confirm this sharp corner design. it's against everything you think until a composite stress expert explains it to you.

[edit] what i said above is for a layup design. it still holds for a 3D woven "T" preform.

[Carlos]

If anyone should want to design a composite wheel they may like ANSYS Composite PrePost for design test simulation.
http://www.ansys.com/Products/Simulatio ... e+PrepPost

[mep]

Haha after FSAE, I would never ride in a car with carbon wheels.

Any reasons why not?

[Lycoming]

in many of the early examples, you could see the thing flex under lateral loading, putting the laden wheel in a large degree of positive camber. That would be my reason not to...

Additionaly, how easy is it to damage these things in the process of mounting the tire?

[Tim.Wright]

I've seen too many broken ones

[marcush.]

....The wheel does not look very much like it was designed for CF with all those hard edges ....

m,

i know this sounds counter intuitive, but at a right angle transition in a carbon fiber joint - say in an aircraft stiffener or here between the spokes and the rim - a very sharp corner is better.

look at this composite Z stringer from Fokker:


and this blade stiffener:


(if you're bonding or cocuring to the skin,you still want feather out the edge of the footer on the skin, as you can sort of see in the blade photo.)

i've seen the actual pull tests to confirm this sharp corner design. it's against everything you think until a composite stress expert explains it to you.

[edit] what i said above is for a layup design. it still holds for a 3D woven "T" preform.

I do accept your input -no issue here but have you looked at the basically non existant radii at the transition of spokes to the rim? it does not look at all like a designed layup.But then -the wheels did survive all tests ..but to call them ultralight is a bit too enthusiastic ...don´t ask for the price bang for buck this must be insane..

[Tim.Wright]

http://www.sscnorthamerica.com/tuatara.php been around for a long time

They are from the same company as those in the original post