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PostPosted: November 4, 2015, 12:55 am 
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Joined: November 4, 2015, 12:45 am
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Hi everyone I am new, so let me start by saying high. Any ways I plan on building a arial At-om type vehical but I plan on using a front wheel drive Nissan sr20 engine as they have very good support for performance parts, anyways right now I am just trying to get together all the parts and info. Is there any frame prints/plans for a arial At-om type frame. I am going to use knuckles and brakes from a 94 rx7 as I have been into rotary engine type of cars for a long time.
Thanks


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PostPosted: November 4, 2015, 10:27 am 
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Joined: October 13, 2011, 9:19 am
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Location: Denver Co
Grab cad has some models
https://grabcad.com/library/ariel-atom-chassis

But you really need to build the chassis around the suspension design and engine

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PostPosted: November 4, 2015, 11:37 am 
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Yeah that's what I thought, what about crash safety. So do you guys just come up with a suspension geometry and go from there.


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PostPosted: November 4, 2015, 12:19 pm 
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Crash safety is relative. Drive like you are invisible!

A lot of crashes are front, rear or side. Rollover is very important but rare in cars with such a low CG. The At-om has issue with being squashed in half, that's why i added full floor supports, front to back. Do research on the different At-om wrecks. Most crashes are going to be because you went crazy and drove off the road in which you suspension will take the blunt of the impacts. Make sure you have very good safety equipment.

Depending on your perspective...
Industrial Designer: Body then suspension
Engineer: suspension then body

Here are some good steps to start with...
Start with the suspension design front and rear including wheelbase, track etc
Get and engine layout and design the front and rear suspension boxes
The figure out how much room you want the passenger compartment to have including seats and tunnel.

Building an actual chassis from the ground up is very hard to do. lots of guys here do the smart thing and built something proven and change it to fit wt they want.

Rear through as many build logs as possible and remember, this is not an At-om build site, its a car build site. (mainly locost which are sweet :D )

I can assume from your log in name you like rotary engines and can use a Bridgeport?

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.


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PostPosted: November 4, 2015, 1:18 pm 
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Joined: February 8, 2007, 4:20 am
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Location: British Columbia, Canada
Have you considered using the plans for the Midlana and modifying to suit your needs:

http://midlana.com/

It's not an exoskeleton like the At-om, but you could make it so by leaving off the body panels and changing around some of the chassis tubes, if that's what you're after. Might give you a good head start.

Either way, I highly recommend the Midlana book, as it has a lot of useful information for building a scratch built mid-engine car, even if you go with a different design.

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PostPosted: November 4, 2015, 4:33 pm 
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mjalaly wrote:
Crash safety is relative. Drive like you are invisible!

A lot of crashes are front, rear or side. Rollover is very important but rare in cars with such a low CG. The At-om has issue with being squashed in half, that's why i added full floor supports, front to back. Do research on the different At-om wrecks. Most crashes are going to be because you went crazy and drove off the road in which you suspension will take the blunt of the impacts. Make sure you have very good safety equipment.

Depending on your perspective...
Industrial Designer: Body then suspension
Engineer: suspension then body

Here are some good steps to start with...
Start with the suspension design front and rear including wheelbase, track etc
Get and engine layout and design the front and rear suspension boxes
The figure out how much room you want the passenger compartment to have including seats and tunnel.

Building an actual chassis from the ground up is very hard to do. lots of guys here do the smart thing and built something proven and change it to fit wt they want.

Rear through as many build logs as possible and remember, this is not an At-om build site, its a car build site. (mainly locost which are sweet :D )

I can assume from your log in name you like rotary engines and can use a Bridgeport?


I do not own a Bridgeport mill, a Bridgeport in my word is a type of porting done in a rotary engine.


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PostPosted: November 4, 2015, 9:59 pm 
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Joined: November 4, 2015, 12:45 am
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Since this has to be designed around the suspension and engine, what kind of suspension would you follow for its geometry, I was thinking about copying the dimensions of my rx7 suspension as they already have a very good track suspension.


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PostPosted: November 4, 2015, 10:30 pm 
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If you have one kicking around or can source one, you can shoehorn in a U13 Bluebird front subframe, and replace the rack with adjustable toe links.
Then just use the existing Nissan suspension components, axles, uprights, control arms, etc.
It'll be much simpler than designing it all from scratch, that's for sure.

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Emissions & fuel economy haven't exactly been areas of strength for past rotary power plants, but absolutely no one with a soul has ever cared.


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PostPosted: November 5, 2015, 12:27 am 
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Joined: January 10, 2008, 4:47 pm
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Quote:
Yeah that's what I thought, what about crash safety. So do you guys just come up with a suspension geometry and go from there.


We have had some successful builds like your interested in. I don't think there is much information on doing it yet though.

I don't recommend using a production car's sub frames and suspension arms. You land up with the compromises the designer of the car had to deal with and also a lot of extra weight and sometimes space too.

Quote:
But you really need to build the chassis around the suspension design and engine


This is basically true, but I found I had to go around in circles to get it right. There are things that are hard to change and other things you can adapt. The suspension can't really be designed before the frame and the frame can't be designed
disregarding the suspension. The engine and drivetrain are sort of givens.

Spend some time looking around. If you are sure you want a FWD based middie, look up the Midlana already mentioned. It has a good book, other builders and it's own website. Kurt the author is a member here and frequent poster. We build alot of Lotus SUper 7 and Locost based cars here. I also designed the Car9 and we have 3 builders of that. It's front engined and a more robust Super 7 type roadster.

If you want to go your own route this is a good place to be but figure it may take a huge investment of time to do a good job.

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