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spaceframe 240-Z update


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I would recommend Herb Adams' book, Chassis Engineering. There are others out there as well that discuss frame design, but this one is very straight forward.

 

For the most part though, I just looked at what others were doing when building spaceframes and began designing by integrating some of their ideas. I looked at kit car frames, circle track frames... everything I could find. I modeled some on the computer and I discovered that some frames are just horribly over-engineered with lots of useless weight. By running various iterations of the frame, I came to one that I thought was the best compromise of weight and torsional rigidity.

 

Here are a couple of links I found useful. The first link shows a Mustang, the owner of which was very helpful in answering some of my questions regarding computer modeling though he is a very busy man.

 

http://www.carter-engineering.com/preston67compcoupe.htm

http://www.beardmorebros.co.uk/website%20pages/new_project.htm

http://www.grabercars.com/Mambosite/index.php

http://www.kimini.com/

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It does look like a good article... although much of the math is over my head. They also seem to spend very little time on some of the more important topics in my opinion. For example, I'm kind of surprised that out of 153 pages, they only spend about a page and a half on roll center and roll axis. The tire and spring tech sections are pretty useful though!

 

Again, I highly recommend getting Chassis Engineering if you don't already have it. It covers almost all of the same information as in the .pdf, but does so in a brief and easy to understand way.

 

At any place that Chassis Engineering isn't in-depth enough, take a look at Milliken's books "Race Car Vehicle Dynamics" and "Chassis Design: Principles and Dynamics." Very good references.

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so Boodlefoof, what are you thinking for a rear wing or are you going to have one at all? Your car is going to be sweet if you ever get a windshield made...I think the windshield is going to be harder to get than your space-frame...

I love that pic of the body of your car on the ground. I would like to do something like that one day but built like the Maserati Birdcage with small(er) sized tubing.

*addition*

I think a lighter frame could be built with the smaller size aluminium tubing and lots of triangualtion. you could probably shave a hundred pounds off of your frame by doing the small tubing. Here is a picture of a birdcage if you have never seen one. Of course it would have to be TIG-AC welded.

goodwood05-1169.jpg

I'm not critising your design at all as yours is just fine. You probably know a lot more than me about frame design. And since you don't have a full frame jig to build off of it would be hard to make the birdcage design cage.

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Olderthanme,

 

In the end the spaceframe will come out to about 300 pounds. This puts me on track for a total car weight of 2000 pounds or less, which is my goal. If I could of afforded it, I would have made the frame out of titanium or AlBeMet instead. Same design, half the weight, stronger than aluminum.

 

I really don't know how much weight would be saved by using thinner wall tubing, because you would have to use so much more of it. I didn't model out any designs with such small tubing.

 

On the rear wing... I've been toying with the idea. Not sure if I'm going to use one or not. If I do use one, it will be an adjustable... it is always a tradeoff of downforce v. drag. It would probably end up being something like the wing on the GT cars like the C5R.

 

And as for the windshield. I'm still not worried about it. If I can't build one out of actual glass, I'm not opposed to going lexan if I have to.

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I was thinking something like one of those GT wings would be great with the chopped top. You would want to mount it to your frame under the hatch that you welded. (you probably knew that)

300 pounds is not bad at all.

The problem with Titanium is you have to TIG weld it in a closed chamber filled with Argon. What is the AlBeMet? I mean what are alloy componets?

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John,

Nice work on the car - I especially like the chopped roof.

I see your out in Charlottesville - if you make it back towards Hampton Roads, drop me a line and come take a look at the Super Datsun, (I'm in Norfolk) - might give you some ideas on cages, remaining body work, etc..

I leave for Texas at the end of Oct - but should be here until then.

-Bob

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I would be guessing Aluminium Berrylium Metal? :)

 

Dave

 

 

Dave wins the prize! ;)

 

With the Ti though, I've read some snippets in welding books that say you can MIG weld (pure argon shielding gas). They didn't mention anything about special booths or anything... just that you will need to set your welder to a hotter setting than for comparable gauge mild steel... and of course use matched welding wire.

 

As for the wing again, the frame design meets the rear hatch right at the point I would mount the wing. I'll probably rig it with provisions for the wing so that I don't have to do further modifications if I decide to experiment with one.

 

Bob, thanks for the invite! I've recently moved up to the DC area from Charlottesville earlier this summer. Unfortunately, I'm starting a new job in just a few days here and probably won't be able to make it down, but I'd still love to see any pics or hear any tips you might have. Were you a TZCC member by chance? I made it down to the Z show a couple of times, but never entered a car. I was a ZCAR member before moving up here.

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I wasn't ever a member of TZCC - to my own loss. I was just too busy between Flying, Navy duties, and Rowing here locally. Shoot, I've only hit the road course twice in the last two years - not normal for me! I'm trying to go one more time before we head out of here in Nov.

If you want pics, etc.., just ask - it really helps if you see it in person.

And to anyone reading - the invite is open - just drop a line.

-Bob

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  • 2 months later...

Thanks for the link Sven. I've been looking at a similar product called "Percy's Speed Glass."

 

Unfortunately, work has been very busy and I haven't had time to tinker with the car in a few weeks. It will still be awhile before it is time to address the glass issue. My next step is to bend up the overhead portion of the frame in my new tubing bender, and then (hopefully) get an engine and trans so I can finalize the dimensions for the trans tunnel to get that squared away. I want to try and get as much of the mechanical and welding work done as I can before I start putting the body on (so it doesn't get in the way).

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