So you wanna build an At-om Clone?

[LsFbomb]

I really like this rendition.

With a LSx motor/F40.

[kikiturbo]

talk about lack of triangulation..



http://velocityrails.com

[JonW]

The delivery schedule might have been revised. Haven't seen this car before. Might still be working on the "perfection" part.

"Still testing/refining. Kits will be available summer 2011. Perfection and the highest quality take time."

All TIG welded. Too bad the welder has to work in the overhead position.

[FlightService]

What is with spelling it with the hyphens? Does Ar-i-el sue people for saying At-om?

[JonW]

Something like that.

ce-ip dot com came after me. Via internet search. If you say you're building a car that looks or smells or drives like one.

Unauthorized use of trademark.

[Bobber]

Has anybody anywhere at anytime done a structural analysis of this chassis?

[Bobber]

Finished a structural analysis on an Ar-i-el At-om chassis. Less than 1,000 ft lb per degree torsional rigidity. Currently having a discussion on this car on an engineering forum. There are some interesting thoughts on them and their design. Engineering consensus: "It's an artsy little car, and that's about all".


Sent letter to TMI Autotech for design verification.

[mjalaly]

Finished a structural analysis on an Ar-i-el At-om chassis. Less than 1,000 ft lb per degree torsional rigidity. Currently having a discussion on this car on an engineering forum. There are some interesting thoughts on them and their design. Engineering consensus: "It's an artsy little car, and that's about all".


Sent letter to TMI Autotech for design verification.

yeah but i dont think that analysis is right. What did TMI say?

[Bobber]

I'm still waiting to hear from TMI. I'm also still looking for independent verification. I recall your mentioning a 4000 ft lb per degree number. What chassis was that for? Anyone actually tested one?
(I Need to know if I effed my analysis but scientifically it has to be done independently).

[Bobber]

I feel I owe this post a follow up. I never heard back from TMI. We had a huge discussion of this on an engineering forum – and engineers can’t explain why a car that is torsionally soft is so fast in venues with curves. Much discussion, however little data was exchanged. But basically, the consensus was as Mjalaly said, to summarize: “There’s a lot of things wrong with the car but a few that are right. And those few that are right, overpower those that are wrong.” Good words.

I have to add that it happens that there is some money on finding a venue that will show up the weaknesses in an Exo. This is gettin’ better ‘n better.

[a.moore]

I don't think soft frames are necessarily bad if you get the few things you're talking about right. From my experience the problem comes when the balance is off and you try to start tuning with springs and ARBs - the "spring" connecting the front and rear suspension isn't stiff enough and you have to make huge changes to get anything to happen.

The car with the softer chassis is going to be more forgiving as well since the chassis will have to flex before the car responds to inputs. With a stiffer chassis this will happen a split second sooner. This may not be a terrible thing in terms of a high power mid engine car with no computer aids.

Even a "soft" chassis by today's standards is probably light years ahead of what was being used 40 years ago. Prior to caging my Sprite, I couldn't open the door if I had the car jacked. One time I opened the door before jacking the car - the door was a good 1/4" off from where it should have been when I tried closing it. I kind of want to get another tub and do an actual torsional rigidity test. I bet a book Locost frame is stiffer.

[horizenjob]

and engineers can’t explain why a car that is torsionally soft is so fast in venues with curves. ... as Mjalaly said, to summarize: “There’s a lot of things wrong with the car but a few that are right. And those few that are right, overpower those that are wrong.”

If your camber curves and weight distribution are in a ball park you may not need a lot of rigidity. Lots of secondary issues though. Bobber for instance your worksheets on chassis forces won't work because there is no reason to think the front and rear of the car roll the same amount. So you can't redistribute the dynamic weight transfer from accelerating laterally or longitudinally.

Chassis flex will give difficulty mounting things to the chassis, even doors like Andrew mentions.

There may be chassis fatigue issues because the lack of stiffness is indicating bending loads on the tubes and they will stress at the nodes. This is especially bad if the chassis is stiff some places and flexible others. Tube frames should be checked for cracking at these nodes especially flexible frames.

When we did the torsional rigidity test on the Locost chassis, there was a tube in the engine bay that was subject to more than 5 times the stress I allowed for any tube on Car9, and the stiffness of the chassis was nearly an order of magnitude lower. A small difference in build procedure like how you attached the floor in that area or relocate the tube an inch or two would probably cause frame cracking.

I wonder if you see any issues with lack of shock absorber ability on those cars?

[mjalaly]

I actually plan on testing my chassis in the garage to see what I get. I am trying to figure out the best way to this though.

Maybe this way? You can see the testing 3/4 of the way down
http://dpcars.net/d2/d2f.htm

not sure if measuring at the wheels is better or just use the frame only.

Also, the engine acts like a brace for the rear suspension box... right (ignoring the flex in the bushings)? Well that was my thought and the reason i did it that way to some extent.

[JonW]

I considered testing mine but never got around to it. Frame only, no bushing slop.

I would fix the one end of the frame by jacking against a ceiling beam or my van rear bumper. Then load other end of frame and measure deflection. Be sure your measuring pointer is not influenced by the loading cantilever.

[mjalaly]

I considered testing mine but never got around to it. Frame only, no bushing slop.

I would fix the one end of the frame by jacking against a ceiling beam or my van rear bumper. Then load other end of frame and measure deflection. Be sure your measuring pointer is not influenced by the loading cantilever.

yeah but i don't have bushings....

where have you been too? I haven't seen a post from you in a long time