Aluminum monocoques?

[James Hunt]

Whenever I read about monocoques on this site it always refers to carbon fiber based . I know of at least one team who has used a Lotus 25 style aluminum tub, but why are the space frame/monocoque debates always centered around just carbon tubs?

[Pico]

Everyone is crazy on weight savings and a carbon composite sandwich structure combines the lightweight, strength and geometric flexibility that these teams want. Also not seeing any aluminium monocoque structures at any competition, people are hesitant to go about designing one since its easier to make a steel frame or if they have the means they do a carbon tub. People are skeptical when you propose to move from the general trend.

[exFSAE]

My favorite are how so many teams are crazy on weight savings that they build floppy, compliant cars and throw grip and handling out the window.

[tgman]

Quote from our current tech director

"DON"T DO IT"

While we still use an alum honeycomb sandwich panel for the chassis the new rule changes have meant that large sections of the chassis have to be covered with carbon anyway and its basically impossible to make curves or anything other than a straight line.

The main reason we persist is that in the past lots of research has been done on the panels and their construction method. Resulting in a process that can be almost done entirely by hand with high strength and durability.

It can work well but under the new rules its much easier to build a carbon monoque. On the flip side it is a very stiff material that holds potential. It just requires a bit of work and allowances from the rules committe

[Mehul Botadra]

I think a team from Czech Republic had an aluminium monocoque, rather it was a semimonocoque with a spaceframe in the rear. They said it was a little heavy compared to carbon, but gave them weight distribution of 50-50! Atleast quite near to that figure.

[ed_pratt]

I'm pretty sure Cardiff ran an alu monocoque a few years back, not sure how it went though.

Ed

[James Hunt]

Thanks for the replies!

Yes, a semi-monocoque would be the initial idea. I'm sure it would weigh more than a carbon tub, but would it weigh more than an average space frame? Our options are either an aluminum/honeycomb tub, or a steel spaceframe. Carbon isn't an option.

In regards to weight, sure there is a point of diminishing returns?

[Mehul Botadra]

It'd be lighter but I cannot give you ballpark figures. Somehow you could just manage to make it heavier! It totally depends on the load transfer. Also I'd be wary of aluminium in fatigue loading, it totally sucks at it.

Depends on how you design it.

[Jay Lawrence]

In 2008 UoW were 188kg, and in 2009 were 198kg (both with turbo intercooled 4 cylinder spaceframe), so there's no reason a spaceframe car can't be light.

[Pico]

Originally posted by James Hunt:
Thanks for the replies!

Yes, a semi-monocoque would be the initial idea. I'm sure it would weigh more than a carbon tub, but would it weigh more than an average space frame? Our options are either an aluminum/honeycomb tub, or a steel spaceframe. Carbon isn't an option.

In regards to weight, sure there is a point of diminishing returns?

If you really want to make an aluminium monocoque you should look into airframe design as you can make it pretty light while being easy to make and stiff enough for your application.