Chassis

[lazybump]

I will be glad if anyone can help me out with this.. Which type of chassis is better, a Monocoque or a tubular space frame? I mean i know the best in the carbon fibre monocoque but the problem is that India lacks racing industry and getting a monocoque is going to be very difficult here and very expensive by far. Any suggestions on this one?

[exFSAE]

Oh? Why is carbon monocoque the best?

[DG]

You pretty much answered your own question there..

[The AFX Master]

The best chasis is that one that you can build fast in order to get the car early.

If your car weights 550+ pounds, but is finished early and properly tested.. you'll blow some competition, and some monocoques too.

[J.R.]

Originally posted by The AFX Master:
The best chasis is that one that you can build fast in order to get the car early.

If your car weights 550+ pounds, but is finished early and properly tested.. you'll blow some competition, and some monocoques too.


Hmmmm.... If you show up in a car that's 550+ lbs, then perhaps you are taking the "get done early" thing a little to far....

That being said, first year team, and Indian team, both due to resource constraints, go with Steel.... And get it under 550 lb. If you're done that far in advance, just start pulling parts off!

[The AFX Master]

How much does Stuttgart weight? Not 550+, but i'm almost sure they're about 500 (Correct me if i'm wrong).. And Stuttgart kicks some serious A...

Get done early is the way to go

[Wesley]

I think they were about 480 lb.

They were behind us in tech at MIS, I should remember better...but they quoted the weight in kilos, so my mental conversion didn't stick with me.

[Peter7307]

India lacks racing industry and getting a monocoque is going to be very difficult here and very expensive by far.

Welcome to the place and enjoy your stay and the process of the competition.

Your statement quoted above suggests tube chassis is the best option on your case.

Finding a good welder is a lot easier than finding a good chassis and a rigid lightweight tubular chassis can be competitive as Stuttgart have shown.

Having some visible progress is a great motivator for your team members and getting sponsorship is also made easier (somewhat) if you can show the sponsor how far you have come already.

Finally expect some damage and changes to be made to your machine over the season. A tube chassis is easier to repair than any other sort.

Good luck with it all.

Cheers , Pete.

[Bemo]

At FSAE in Michigan 2008 we took part with our 2007-car (as most European teams). The official weight was 502 pounds. Result was a sesond place overall.
Our 2008-car weighs 210 kg, that should be clearly under 500 pounds (still with a tubular space frame).
For a first-year-team that's propably not achievable. In my opinion in your first year you have to build a simple car, that just works and that you can get done fast. You won't be able to compete with the international top teams anyway. Finishing the Endurance is a goal you should work for.

[lazybump]

Thanks for the replies.
I get the point that making a chassis which is the fastest to make is the best option. But if we guys want to go in for a tubular frame and leave out monocoque, which material is the best suggested for a team making a car for the first time.. Steel??

Thanks in advance..

[PatClarke]

Lazybump. of course your tube frame chassis should be steel! What else would you use? India has a huge bicycle manufacturing industry, so clearly good quality steel tube is available there.

The majority of FSAE/FS race cars are steel spaceframe cars for a good reason. Easy to build, easy to understand and easy to repair or to modify if you mess up the design.

Personally, I like FSAE spaceframe cars, because I think the students learn more about intuitive load paths.

Visit the Australian FSAE site or the German FSG site and download the paper I wrote for first year teams. This paper is getting a bit dated, but is still good advice for a new team.

Welcome to the best Student engineering competition in the world.

Cheers

Pat Clarke

[lazybump]

Thanks everyone for helping me out. I have another question. We have both Mild steel and chromoly available but which one is better to use for a team making their car for the first time. All welding equipment is available here.
Id be glad to get all the pros and cons. Thanks alot..

[exFSAE]

CrMo steel welds like a champ... and tends to be available in a WIDE variety of diameters and wall thicknesses.

Mild might be cheaper but you don't have quite as many options, at least that's how I remember it.

It's not like mild is difficult to weld at all, but I don't remember it being quite as nice as CrMo.

Both are equally stiff, and stress is generally not a concern on a frame for these cars (especially when designing for stiffness!)

[kapps]

We used mild steel previously but switched over to chromoly this year. We started using the same aircraft supplier that our Baja team uses and we were able to get the chromoly for cheaper than we had been paying for mild. They should both weld fine, and with the thicknesses in these cars, you shouldn't have to be overly concerned about stress relieving the chromoly.

[vandit]

@ lazybump

which college dude .... lucky guys to have chromemoly easily available ... when we tried looking around , chennai was the only place we found supplier ... i read it somewhere on this forum , there was team who went to monocoque and then came back to space frame ... i dont know reasons ... but i read it long back ..

[JamesCH13]

I would recommend the CroMoly (4130 I assume?) we used that in our first car and I welded the entire frame with a scratch-start TIG. We've since upgraded to a Lincoln TIG Precision 375. Use ER70S-2 filler if possible, ER80s-D2 also works very well. ER80s-d2 will be stronger (80ksi yield) than ER70S-2 (70ksi yield) but ER70S-2 is a better filler for out-of-position welding because of how it flows. Also, remember that when welding overhead (I hope you don't have to) crank up the heat and let the arc forces keep the puddle up, don't run cold.

If you have it, use an auto-pulse function, check out a little experiment I did when developing a welding code for our team:

http://www.weldingtipsandtrick...bing-with-pulse.html (http://www.weldingtipsandtricks.com/tig-welding-4130-chromoly-tubing-with-pulse.html)

Good luck.