Hey peeps,

I'm probably a few years from actually doing any physical work and just looking for opinion on what I'm thinking is actually feasable

I'm really interested in classic/vintage cars and would love to do an Austin Seven 'Sport' in the future; possibly with composite framework/ panels!

My inspiration is the Super Accessories Sport

Thes were originally made using 2x1" Ash frames covered in 20g Aluminium sheet mounted  onto the original chassis.

Now for the multitude of questions!!

1) What carbon fibre/ core setup would give comparable/ better properties for the Ash frame?

2) What CF setup would be comparible to 20g Aluminium?

3)If I were to make my own floor would this seem a reasonable setup (going from side that would be closest to the road):

   [Road Surface] Aramid/CF - CF - Core (Honeycomb or Other?) - CF - CF [Inside Car]

4) The floor would likely to be made of three sections to incorparate the transmission tunnel, what would be the best way to connect them that would allow them to be removed from the frame is need be? (i.e. bolted through metal sleeves or similar)

5) If it is possible to make a frame of CF/Core/CF; I would look to using vacuum resin infusion. If the part is a simple flat piece, like a U-shape, would a mould be needed or can it just be done on a flat surface with the underneath of the bag taped down?.

6) The body consists of a 4 piece boonett (for access to both sides of the engine bay, front panels, radiator cowling and main body; for the smaller pieces I would use a male mould but a female mould for the main body. What would the ideal material/methods be for creating these moulds?

7)If it is possible to create the frame and body parts as mentioned above, what would be the best way to attach the body to the frame sections; is it best to bond brackets to the body that can bolt to the frame (which allows parts to be remaoved/repaired if need be) or would you suggest something else?

Sorry for all the questions but I want to know if it's feasable at all as I've never worked with composites before and don't want to end up barking up the wrong tree.

Thanks for your time and patience.

Cheers,

David

The feasibility aspect all depends on how much money you are willing to invest, along with the time it will take, no only to learn how to manufacture composite components, but to build the car itself, more or less from scratch. If money is no issue, then it is by all means feasible.

I wish to do something similar, and I am still toying with the idea of putting a composite body on a classic car, or to build a body from scatch in aluminium, for which
I would need to learn panel beating n english-wheel first.

Someone is doing a replica of the type 57 atlantic coupe with composite panels. It is a huge undertaking, and although admirable I cant help to think that it is such a waste of time because he is using a shabby old pick up truck chassis and fiberglass for the body panels. Whereas I would use the frame built for a sportscar, and pure carbon of course, with kevlar where needed. Heres the link: http://home.roadrunner.com/~trumpetb/57SC/

As for the chassis, I would probably stick to chromoly steel tubing rather than trying to make it from composites, that wouldnt work too well in the long run I think. Possibly a monocoque type construction.

Regardless, what we are talking here is very advanced composites stuff.

Good luck, and others will surely answer your subquestions.

cheers

baja,

thanks for your reply, it would be a very long term project, and still a few years from starting it yet. so hopefully I can get funds sorted by then!

the link you sent is very useful and nice piece of inspiration.

chassis wise it would be an actual Austin 7 chassis with body/frame/floor bolted to it, as per original manufacture.

Austin 7 specials had there heyday in the 1950s/60s with various bodies available to put on the chassis (my design inspiration being one of those) so the mechanical side of things are already there, it's just a case of building a body to go on top.

the 7 is only 750cc and at least 75years old so any weight saving is going to be very useful!

Hope this clears things up a touch.

Cheers,

David

Bit of a thread revival but I am (oh so very slowly) getting there.




This coming weekend I'll be picking up some Austin 7 Ruby front wings which I will look into doing a mould of (using uni-mould) and making a composite version.

Would the following seem like a reasonable setup or over/under-kill?:




Top Layer

1. https://www.easycomposites.co.uk/200g-green-22-twill-3k-carbon-fibre-cloth
2. https://www.easycomposites.co.uk/200g-profinish-coated-22-twill-3k-carbon-fibre-cloth
3. https://www.easycomposites.co.uk/3d-core-infusion-foam-core
4. https://www.easycomposites.co.uk/200g-profinish-coated-22-twill-3k-carbon-fibre-cloth
5. https://www.easycomposites.co.uk/200g-22-twill-carbon-black-twaron-cloth

Bottom Layer

Thanks in advance for any advice.




Cheers,

David

Hi,

That sounds like a very good setup, but for the mud-guards alone, I would not spend money on 3D-Core, I would recommend 2 mm Soric.

My new infusion test shows quite clearly that 2mm Soric gives less pinholing/better saturation on the top layer, and less noticeable print-through on the bottom, than 3 mm 3D-core.

I'm convinced that a 3 mm Soric will be better and cheaper, but also a little bit heavier than 3D-core.

I also tested cheap 2 mm floor-damping cork, which works very well, but does give more pinholing/less saturation of the top layer (The one facing the mould)

I have decided to make some panels using wet-lay with vacuum bagging and the cheap cork floor mat as core.

For parts like these, I would recommend spraying (Get the Gel-coat Cup-gun!) GC50 into the mould, then infusing on top of that.

Reinforce the mud-guards with extra thicknesses of CF/Twaron in strategic places. 

(Basically do it like the "Car-bonnet tutorial")

The curved surfaces/shape of the mudguards will make the finished product very stiff and strong.

Good Luck!!

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Looks a little heavy (to me) but it depends on how light you want to take it and how bothered you are about surface finish/print through from the core. 

Thanks for the response guys,




Dravis -

Thanks for the advice, I was thinking of using the resin infusion technique.

I thought of using 3D-Core purely because of the curves of the wings I wasn't sure if the other cores would form as well; but if you think the 2mm cores will work then I may possibly go for the cork core, and fill the pinholes with resin before clear coating. The cork feels more in keeping with a 'special'!

The car bonnet tutorial was my inspiration for the idea.

Where would you think would need strengthening on the mudguard?




ChrisR -

The reason I looked at using 2 layers either side of the core was because of print through, though maybe I can just use the single layer of Aramid underneath as it won't really be visible.

I don't mind if it's a bit heavy I can't afford to spend a lot at the moment so would rather make a robust version to start with, and when future funds allow, look at seeing if lighter versions are feasible.




Cheers,

David

I tend to agree with ChrisR on the number of reinforcement layers, especially for the wings, you probably will not need more than a single layer on the "bottom"

Regarding reinforcements, you will definitely need to replace the Soric or cork core with solid CF/glass in the places where you attach the "wings"  and maybe make an extra layer of CF/Twaron/Glass that extends a bit from the attachment point.

I have made long "old style" motorcycle mudguards, using just three layers of CF, but to stop them flexing along the length, I added a narrow strip of soric along the edges just inside the edge curve. It is invisible from the outside, but stiffens the mudguard so it feels completely rigid.  (Hope this makes sense .. )

I think that the pinholing issue with cork, may well be due to the fact that I used cheap floor "noise insulation" cork, and did not prepare it for infusion. I also did not use infusion mesh all over my test piece, only the ends.
(like you would with Soric)

I think that if I had done what Warren suggested to punch a grid of holes in the cork, and maybe score the surface in some way, the pinholing may have been a lot less.

The specialized cork for composite use is still cheaper than the Soric, and probably performs better then my cheap floor stuff.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Thanks again for the advice, it's very. very helpful.




I will probably take inspiration from your idea of using strips (how wide?) around the edge to add rigidity, would you suggest putting the core material between layers or exposed/ covered by clear coat/ under-seal?

With regards to mounting, I'm not entirely sure at the moment, but may look at using the adhesives you can buy and attach to the body/chassis a well as probably a light mounting bar.




Cheers,

David

The strips of Soric were put in like a normal sandwich core, under the bottom layer, remember they were used in mudguards with no core in other parts.

I do not think they will be needed at all in a fullu Soric or Cork cored layup.  I would use peel-ply on the bottom, that will make it very easy to add some extra strips of CF tape  along the edges, if more stiffness is needed.

Also extra reinforcement can be easily added in high stress areas..

There is a thread on this forum where someone is making wings/mudguards for an Caterham/Lotus 7 but I could not locate it  in a hurry..  may be wort a closer look?

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)