Aluminum Semi-Monocoque?

[Ben Shelton]

Has anyone here tried an aluminum semi-monocoque?

I'm thinking of trying one for our 2008 car. Maybe something along the lines of a Lotus 25/33, with two D-shaped tubes on the sides joined by bulkheads and a floor panel. It seems to offer advantages in weight and stiffness over a spaceframe while being easier to fabricate than a carbon fiber monocoque.

I have a couple of specific questions:

How did you fabricate your bulkheads? From sheet metal? CNC?

How did you mount the engine - directly to the monocoque or with a separate spaceframe?

What type of epoxy did you use at the seams?

How did you jig it up during fabrication?

Thanks,
Ben Shelton
Frame & Suspension Design Leader
Duke University Motorsports

[Bill Kunst]

You would be looking for the madison car, I presume. Find dhaidinger on the site and ask him, as he will be able to tell you more. Madison had a pretty successful car design of this type for some while.
Bill

[James Waltman]

I don't think that the Wisconsin-Madison guys ever went further than an aluminum monocoque center section.

I think you would be more interested in something like the guys at Queens were doing from '99-'03.
http://engsoc.queensu.ca/formulacar/galleryindex.htm

[SNasello]

I would have to disagree with you that it would be easier to manufacture than a carbon fibre monocoque. Working with CF isnt particularly dificult. The only downside to using it is the startup costs. For one you need an oven big enough to cure the carbon in (at about 120C) and then materials. You just need to be creative with the mould.

Also, It is very possible to make a light weight steel tube frame car, albeit difficult. Im not too sure how heavy steel tube frames are but i believe our monocoque this year weighed in at about 40-50lbs (est) with roll hoop.

Im sorry, i can't speak for what Queen's was doing from 99-03, im not too up on our previous cars.

[Buckingham]

Between 2001 and 2004 we successfully (2nd, 4th, 9th place finishes in that time span) ran an aluminum monocoque center section (roll hoop to roll hoop) consisting of two D-shaped sidepods. The monocoque was fairly simple to build once you understand the process. I would recommend doing research (aircraft fabrication) so you understand the build process for properly fabricating riveted/epoxied sheet metal structures. Like any endeavor, I recommend a thorough cost/benefit/rules analysis before you make your decision.

[Psychosis]

Originally posted by Stefan Nasello:

Also, It is very possible to make a light weight steel tube frame car, albeit difficult. Im not too sure how heavy steel tube frames are but i believe our monocoque this year weighed in at about 40-50lbs (est) with roll hoop.


you'd be right in that assumption, our steel chassis weighed in at 50lbs this year fully bracketed. i suppose the difference may be in the stiffness numbers, i don't have them but as far i feel we made the best possible use of material to meet the intent of the rules. our chassis was a few lbs heavier than last years to ensure it was super stiff.