New chassis

[pauljones]

Hi all

As part of my Engineering course I have to choose a project. Mine is to redesign the lotus chassis......A big task but to be fair its only to show an understanding of CAD, not something that has to be reproduced.
So to help me out can anyone post a link or show photos with dimensions of the chassis. I will be concentrating on the engine bay area leeding into the transmision. The idea is to "construct" it out of round tube alluminium with a walling to suit,for this I must show a calculation of strength v's another material ie bending moment, weight, cost etc.
I would measure my own but its down South and im up North.
If anyone has experience of this or cad pictures that you think could help, and dont mind me using them in my work,correct references being given to contributions,then I would be very grateful.
As part of the development for the future once the base design plan has been produced,i intend to design a kind of inboard suspension system for the front and rear,again this wont be for production but will be to show that I can adapt the origonal idea and develop it in principle.

If anyone can help or point me in the right direction for reference material all round good eggs that have helped in the past then i would be very much grateful
Paul

And yes this is what is stopping me fix my lights, install the rest of the dash, driving my car in general.

[garyeanderson]

Does this one help

Gary

[pauljones]

Thanks Gary

Now I didnt find that on google..Thats a cracking start..

Cheers mate

Paul

[garyeanderson]

I did some silly line drawings and they are located in DJ Pelly's topic called

Monocoque

elan-f14/monocoque-t23910.html

probably worth a quick look, maybe get a laugh or two

Gary

[AHM]

Paul,

Nice idea - I suspect that you will be the first to use a modern CAD package to analyse this design.

I think you will need to, and should anyway contact Lotus Cars - They would probably give you more detail as well.

My advice would be to make the project more real world in its objective. You have a known design and 50 years of user testing. You could compile a list of failure modes, run your CAD model and compare the results. Then redisgn the specific areas. Your proposed improvements could show the analysis of different materials processing etc

You will have covered the same technical content, but in addition will have compared it to empirical evidence, be able to propose real world solutions and have advanced knowledge in this field. You would have a more complete piece of work.... something that you could use in a job interview!

Simon

[pauljones]

Gary,
I just had a quick read of that thread,very interesting but it does highlight a few points beyond my current knowledge.

Simon,
To keep this in the initial time frame the project has to be in end of Jan. I think to do full justice would take me a bit more time than I have,although it has a section on further developments.

Part of the thread Gary pointed too says a rectangle box section is stiffer than a round tube torsionaly,is this correct or am I reading it wrong. I was thinking a transmission tunnel cunstructed out of say 20mm dia, 2mm thick aluminium round tube,with triangulation at 45degrees across the sides and over the top.Surely this would be a more ridgid structure than a rectangular structure with reinforcing of the same,as in the through pictures of the red chassis.

I will when ive finished the CAD transmission tunnel post up a picture of the central spine,but please bear with me,it will take a while to learn how to do it.

If anyone has any ideas please post them up and ill see what i can do.Its purely for fun and not too serious so anything justifyable goes.

Paul

[pauljones]

Well here is my mornings work so far,hope it comes up.Its still developing so i may post up when it gets better.

[jk952]

Why not duplicate the present design in cad, then run the FEA package in your software to show stress areas with a static torsional load, then as part of your project suggest strategic improvements. Costin and Phipps suggested a 4.5g diagonal bump load -a good place to start. If you needed some dimensions not on the diag Gary posted I could measure them (approx) (have a chassis open). Metal thickness is I recall about .075-.080 inches, whole thing only weighs about 85 lbs.
Just a thought, I would be interested in the result and I imagine others.
Jack

PS Simon, I just read your post more closely, looks like my thoughts are almost the same...

[PanoGuy]

I really like the Spyder frame, owned one for a long time, but it's stronger because it's heavier. All things being equal, the sheet metal Lotus frame will have the better strength to weight ratio. Else why did race car technology go from tube frame, to sheet metal, to "we bake them in ovens like cakes"?

[pauljones]

Jack,

I've just found out what fea is. I don't have that on my free copy of pro engineer.in fact it won't let me do much,that's probably me not knowing though. I hope to try and use some ideas from both chassis types, but the limiting factor will be the space it has to fit into, it's preety much been nailed by spyder, but I intend to show it as round tubes throughout as best I can.the second limiting factor is to keep the mounting points the same.
During my research period I was looking on eBay at TVR chassis's and these are what gave me the idea originally, lots of triangulated tubes.
When I get better at the cad programme ill finish it of as an initial idea, if I can get a newer version of desktop then it may be worth doing what you say, would make an interesting comparison I'm sure.

Paul

[richardcox_lotus]

A recommendation from me - as a non-structural engineer person. I was contemplating how bloody awful the jacking points (or lack of - especially at the rear) are. As part of your "improvements", may I suggest an incorporation of some form of outrigged jacking support at each end of the sill, as per my attached squiggle (Plan view - improvements in red dotted line). The outriggers sould be part of the frame flange - and be sufficient to give additional structural rigidity to the outer corners. I suspect if we were doing this in the real world there would be an additional bobbin in each corner.

Just a thought !

Regards
Richard

[Chancer]

Other than adding a lot of weight its not exactly bringing anything to the party is it?

You might as well stick with the Triumph Herald chassis which has the backbone, all the correct mounts for the front suspension and outriggers not unlike your drawing, happily Colin Chapman didnt take that route!

Either the earlier CAD drawing has not reproduced in full or its not a lot to show for a mornings work and a long way from holding a car together let alone improving on the Elan chassis, I dont think that Adrian Newey will lose any sleep over it.

[AHM]

Either the earlier CAD drawing has not reproduced in full or its not a lot to show for a mornings work and a long way from holding a car together let alone improving on the Elan chassis, I dont think that Adrian Newey will lose any sleep over it.

Not exactly encouraging words! Have you yourelf used CAD? How quick was your first go?

Paul, you can't say that Spyder nailed it until you have done the analysis... nailed what exactly? and under what criteria? There is a reason that the Lotus chassis is a well renowned piece of design ? don?t forget that during the elan production Lotus won six of their seven constructors titles, and are still the 4th most successful F1 constructor. I think they knew a bit about chassis design! (Without a CAD tube in sight!)

[jk952]

Hi Paul,
For the benefit of any, FEA is finite element analysis. It's been around for over thirty five years but only in relatively recent years has it been more readily usable as computing power became avail. Solid works as others have a light duty FEA usually in their pgm's, I assumed you had access to classroom software. I am working on the ?lan std chassis very slowly myself, but i was never fast didn't have to do it for a living fortunately! i am so old pc's hadn't been invented when I studied. I used solid works for a spring comp. special design for a tight access car and did the FEA to see hot spots (4140 pre hard) and if strong enough, had the part made at a local shop, and it worked fine, and i'm still alive
One's first project is always tedious, keep it simple. Proficient Cad designers all say it takes five years to really get good at it (ie complicated stuff) so don't be discouraged.
Jack

[pauljones]

Having spoke to my tutor we both agree its a masive project so will not be going any further.

Does any one know how to delete this post?
Chancer,Thanks.