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Has any body tried to build a Semi-monocoque styled chassis before either for a front or mid/ rear engine car before?

What I am looking at is more of a hybrid style chassis instead of a full monocoque chassis design. By combining both a tubular and a monocoque style build in aluminum, I believe I would be able to get the strength that is needed and also be able to build it much lighter.


My idea or plan, that I am looking at is a front engine based design, with a torque tube and rear mounted transaxle. To help balance the weight further, with pushrod style suspension front and rear. I would used aluminum tubing for the main rails along with a monocoque based design for the rest of the chassis and to intergrate a large portion of the body work into this.

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Having fun and enjoying the ride

1927 Roadster - custom build
1932 Ford, full one off custom build
2008 Corvette Z06
2009 Mustang GT500
2010 Nissan GTR

Hi RebecaLynn-
Check out KartRacer's build in "Non-Traditional Build Logs" --
http://locostusa.com/forums/viewtopic.php?f=36&t=10658

And Airframefixer, same section --
http://locostusa.com/forums/viewtopic.php?f=36&t=2142

And welcome to the forum! From your Screen Name, I would assume you to be female. Is that correct?
(That only matters because I wanna know whether to say "Sir" or Ma'am"...)


JD "Male" Kemp

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

Yes, very much a female. Been around cars all my life. I have been involved in drag racing, oval track racing and road racing, more from the mechanical side of things, but have done my share of driving also.

_________________
Having fun and enjoying the ride

1927 Roadster - custom build
1932 Ford, full one off custom build
2008 Corvette Z06
2009 Mustang GT500
2010 Nissan GTR

I woke up with the same question on my mind.

Last night I re-watched the Gearz episode where they introduced the Superlite Coupe they would be building up. (This is a good series to get your juices flowing)

http://www.youtube.com/playlist?list=PL16EFF614F8C2F76D

The designer talked about the monocoque design spreading the load over a much larger area than just down the tubes. Somehow that stuck with me and during the night I began dreaming about this.

Would a tube frame without the triangulation but with a stressed skin be stiffer and safer than the traditional frame we've all built?

I have no idea how you could simplify the frame or what thickness of skin you'd need, but it seems that it might help in some of those tight areas. I'm thinking steel rather than aluminum just for simplicity's sake.

The floor is where I first envisioned it as I've stressed the skin on a traditional floor before and then wondered afterwards did I need to go so far.

One pic in the after the fact build thread on the trike (I can't remember the name and it's fallen off the Active Posts list) showed a very simple floor pan which looked to be the starting point for other things.

Since as soon as I can finalize the transmission I'm going to begin building another one I might be interested in another technique.

Any of you FEA wizards out there that could "build" a panel or complex shape and test it both ways?

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

women are usually really bad drivers, but if you get a good one she is usually better than most men.

how do you find the time away from the kitchen to do all the things you done?

should this be allowed?

regards,
Mr. S. Pig

_________________
this story shall the good man teach his son,
and chrispin chrispian shall ne'er go by,
from this day to the end of the world.
but we in it shall be remembered.

This question comes up pretty often. It is just not easy to actually do though. The frame weighs something like 10% of the car weight. It's also what turns a pile of parts into a car and what prevents a serious case of road rash while underway.

It's worth thinking about these things and we have a thread with stress analysis of the frame and at least a couple of people have contributed alternate designs. My take is a roll cage spec'ed by road racing clubs with the remainder of the car attached. I think it's going to come in under 140 lbs. The standard Locost frame is around 120, I think.

http://locostusa.com/forums/viewtopic.php?f=39&t=2224

In the 60's they were trying hard to get their F1 space frames around 60 lbs. They didn't have motor mounts, it was more of a "driver mount" on the front of a Cosworth V8.

Aluminum makes more sense then steel for this because the steel is so thin the sheet buckles easily.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

The thing is the tubes go where you want the load to... So this becomes the problem for the monocoque. The loads come from places, like coilovers, suspension pickups and engine mounts. The monocoque requires work to strengthen it and provide hard points for these mounts.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Sounds to me like a 1st generation Lotus Elan. Another brilliant Chapman design although it seriously lacked side impact protection. The big problem for home builders is you need a pretty big brake to make the parts. Stress calculation isn't trivial either. You will probably have to build then test like Chapman did.

Racing has always been a part of my family. My step-father started racing at the age of 4 with one of the orignal 1/4 midgets. He just retired from active racing a few years ago. Though this was always a hobby and just for him, as a family we worked and built cars. He felt both his sons and daughters should know and understand how the cars worked and how to work on them. So I got my love for cars from him.

I never said I was a good or great driver. I can hold my own on the track, but I prefer the design and mechanical side of things.

I enjoy cooking a great meal, but you could say I am not your typical female in many ways. I can clean up, dress up and hold my own at the same time. In life if you put barriers in your way, then you are not doing the best that you can.

Should this be allowed, let's see.
1- I sereved for almost 16 years in the Navy. Not a desk job either. I was cross trained as an AME and PR. I worked on ejection seats and parachutes for F-14's.
2- Due to my time in the Navy, I am now partially disabled and Semi-retired at 37 years old.
3- It is something i enjoy and love to do.
4- It is my choice.
5- Why not.
6- My family enjoys it just as much as I do. It is a great way to spend time together and do something positive.

CarGuy123-



I have watched the episodes and seen the SLC in person and also spoken with Fran the owner and designer. This is a great car and a great company.


I am going to start to work on a few drawings and design ideas and post them as soon as I can.

_________________
Having fun and enjoying the ride

1927 Roadster - custom build
1932 Ford, full one off custom build
2008 Corvette Z06
2009 Mustang GT500
2010 Nissan GTR

First-- You can come over to my build log any time. We discuss recipes fairly often. (Red Beans and Rice, anybody?) Perhaps you can give us a few pointers, or get some!

Second, AMEN! I should thank my Mama for readin that "Little Engine That Could" story to me as often as she did.

Third-- I ain't in charge of anything in here, but I don't see how which side of your shirt the buttons are on matters. Come on in!!!

And lastly, I'm pretty sure "Mr. S Pig" was joking around... Sometimes folks forget to put the little smiley faces in so we know when they're kidding...


JD

_________________
JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

No problem. I understand about joking around.

_________________
Having fun and enjoying the ride

1927 Roadster - custom build
1932 Ford, full one off custom build
2008 Corvette Z06
2009 Mustang GT500
2010 Nissan GTR

The thought I had was more or less the tubes laid on the skin and then welded onto it instead of making the frame and then welding the skin onto it.

It seems that you could build "in panels" and also it might help minimize welding distortion. It seems that the skin would do a better job than the triangulated bracing.

Horizonjob you say the stresses go where you want them to go, which is through the tubes, but we get back to the we're not engineers in here, so who's to say that is the best or proper place for the stresses.

On one of the current threads they were talking about stress paths of mounting the rear arms and how one way localized it and another way spread it around. How are most of us to know that? Intuitively the way that spread the forces around looked right to me, before I saw the results that is.

If someone who already has it in their computer would electronically "stress" a section such as a side piece or floor and then remove the triangulation and add a skin and stress it again then that would tell us a lot.

I don't KNOW it would be a better way, only another way. But the more I think on it, that's what usually gets me in trouble, the more it seems that for a lot of the car that might make a big improvement. And if everything came out the same but it made for a more distortion free frame then that alone could be worth it.

Sure wish I had some money to go build a couple of panels and test them myself, but it looks as if until we have another election I don't have a lot of HOPE since I'm in Real Estate loans.

But you are right in that it doesn't look like the lightest way to build, that is without some fancy (expensive) engineering.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

If you have an interest in the 1st gen Lotus Elan, Google Lotus Elan chassis images. There seems to be a lot of interest.

I'm sure I've seen this linked to on here before, but there's a blog that seems to do a pretty good job of sumarizing the Elan's inception and history. (http://lotuselan.wordpress.com/elan-in-depth/)

Here's a bit about how the chassis came to be, as quoted from that blog:

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.. in the world

if i was in a competition and RebecaLynn was my competitor i'd be worried, she seems to know her stuff guys,

nice to have you here!

_________________
this story shall the good man teach his son,
and chrispin chrispian shall ne'er go by,
from this day to the end of the world.
but we in it shall be remembered.