Hi,

I have a lot of books on working with foams and skinning with glassfiber to make everything from boats to tail fins for planes. I was also considering this method to make a one off car body shell, which rather than the usual making a buck then a female mould then a final shell which is both wasteful of materials, time and money. I’d rather start off with a simple tubular chassis then build carved foam body which would have the glassfiber laid on top, cut out the doors, carve the inside and skin that too. Basically the chassis would be encapsulated in the bodyshell, the walls would be say a few inches thick foam with GRP either side and so would be good in a crash rather like driving around in a huge crash helmet. I could see that quite an amazing looking car could be done very easily and cheaply. One question is I am assuming that this kind of construction would still be ok with the SVA as it’s not a monocoque. I know there was a three wheeler car built ages ago using this method but has anyone here used it? I’d like a to do a super streamlined 2 seater rather like that Aptera so long as I could get a suitable windscreen from something like an Ultima (anyone know how much one is?)

One of my favourite things is carving or hot wire cutting large model boats hulls and r/c plane wings so this is really just the same thing but scaled up

cheers

Robert Q Riely had a website about his car the trimuter or something with tri in the title. It was made of PU foam with GRP inside and out. The result was much stiffer than, he claimed, than the same weight of GRP as a single skin. He was probably right.

If you are making a plane's tail fin, for example, then you're probably OK as both sides will be skinned anyway. For car bodies like a seven, you need enough GRP on both sides to be puncture proof making quite a heavy body. For a monocoque though, its probably a good thing.

I experimented with this type of construction a while ago. I found that digging out a "pit" every so often so that the inner layer of GRP was layed up in contact with the outer layer added a lot of stiffness.

Robert Q Riley's website has some details on this method which he has used on a number of his designs over the years - see this link for more details.

Dominic

quote:

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Originally posted by smart51
Robert Q Riely had a website about his car the trimuter or something with tri in the title. It was made of PU foam with GRP inside and out. The result was much stiffer than, he claimed, than the same weight of GRP as a single skin. He was probably right.

If you are making a plane's tail fin, for example, then you're probably OK as both sides will be skinned anyway. For car bodies like a seven, you need enough GRP on both sides to be puncture proof making quite a heavy body. For a monocoque though, its probably a good thing.

I experimented with this type of construction a while ago. I found that digging out a "pit" every so often so that the inner layer of GRP was layed up in contact with the outer layer added a lot of stiffness.

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Seem to recall somewhere on the tinterweb a set of plans to make a lambo doing exactly what you have in mind mate...carve a big foamy shape and lag it in 'glass then scoop out the inside like a boiled egg...clever idea if you only want to make the one.

Mark

check this thing looks like a little space ship!! a trekkies dream come true


[Edited on 22/7/08 by Mr Whippy]

Wouldn't the foam be a fire risk? OR is it special foam?
[EDIT] ok... it was a crap question to check my signature was working

[Edited on 22/7/08 by Dangle_kt]

Gecko's link is very interesting - I do like this one


Description

$95 for the plans..........

edit - I wonder how hard it would be to get through SVA ?

[Edited on 22/7/08 by clairetoo]

Back in about 1980 I bought a set of plans and templates for a car called a Centurion I think from burlington cars. This was a body as you describe made from foam and encapsulated in fiberglass cloth and was then bolted to a spitfire chassis. I still have the pack somewhere I can remember it saying that both inner and outer surfaces were covered and these met around the door and window apertures which made it very strong.

quote:

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Originally posted by clairetoo
Gecko's link is very interesting - I do like this one
$95 for the plans..........

edit - I wonder how hard it would be to get through SVA ?

[Edited on 22/7/08 by clairetoo]

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This thread has really got me thinking - the question of a practical , economical comuter kit-car has allready come up , and reading through that link came up with this



Description

A bit of a front end re-style would be all that would be needed to fit a scooby engine.....

practical , economical comuter kit-car with a.....scooby engine?

kind of a contradiction there no? I think a bike engine really is all you want to put in a lightweight 3 wheeler and still be able to keep it on the road.

I think the last one looked nicer the back of that looks like a van and really don't like the weird well what ever that is on the front.

As to Dangle_kt's question about fire risks I don't think they would be any more at risk than an ordinary grp car and yes I think you can buy special foam that is self extinguishing but its expensive.

GRP over foam body construction

Here is the link to the Robert Q Riley tri-magnum build page.