Lotus Elan and Lotus Elan Plus 2 Forums

Hi

Has anyone analysed the weight and handling characteristics of a full blown space framed Elan (with ally floor and GRP skin fixed to spaceframe) rather than taking a modified chassis and shell and adding a cage etc?

If there are no regulations limiting approach, which would be most efficient?

I'd be interested in thoughts on this.

Thanks
Gavin

gav wrote:If there are no regulations limiting approach, which would be most efficient?

A carbon fibre monocoque

You'd probably need really high sills though and the footwells could end up being really narrow.

If using a spaceframe the cosmetic only bodywork could be made extremely light maybe weighing around 30kg or less. The standard bodyshell weighed 90kg on the early models

The standard Elan chassis is 40kg, a spaceframe? who knows?

The Elise in roadgoing form runs around 40kg total for the front and rear clams but I've no idea what the doors and sills weigh but the Elise chassis despite being made of "lightweight" aluminium is 68kg but has got to be at least 10 times stiffer than the Elan chassis- it is also (definitively) more than 5 times stiffer than the Esprit chassis!)

Does anyone have a true figure for torsional stiffness of the Elan chassis?

I believe the Elan chassis has a strength of 950, I think the units are ft.lb/degree in torsion. Interestingly, the type 14 Elite is about 1500...
Patrick

Forbes Aird has published figures on 2 cars for Backbone chassis stifness -
1962 elan @ 4500 lb-ft/degree and the 1968 STP turbine car @ a whopping 35,000 lb-ft/degree - for comparison sake the 1962 lotus 24's space frame is listed at 1000 lb-ft/degree .

Not sure you would want to go the space frame route . Also , the 2500 figure is for a stock frame , adding the 26r /avo mods and the fia cage should raise the figure substatialy ( not to menion saving the engineering by using proven methods , parts etc)

I can't give torsional stiffnes figures BUT 15 or 20 years ago I built a race Elan in the UK using a Spyder space frame which we then modified. Some mods were to fit a Sierra Cossie and Rocket box others were for an Atlas diff and Ralt rear suspension. The bodywork was thinnest possible fibregalss draped over the chassis. The chasis had the roll cage incorporated and a fair amount of other steel to add torsional strength.
The car was heavy at about 1300 lbs but the damn great Cossie lump was part of the weight!
Went like a bat out of hell in Gt racing and won plenty of races. Although I should have gone for longer front wishbones when doing the job - I used the exisiting pick ups with March uprights as I understood the geometry. I should have been braver!
I tested the structural integrity comprehensively. In other words I had severl fairl hefty accidents and every tiem the cahssis remained true - unlike my bank account!
Hope that encourages someone to try the same!
Richard