CommanderAce
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| posted on 17/10/05 at 08:25 PM |
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Roll bar concept
Hi there, before I start my build I'm modelling my entire car in my favourite CAD software, SketchUp, and I thought I'd just pass my roll
bar concept by you good folk and see what you think of it. It’s not final at the moment but it is of the style that I would rather like.
Biggerer
Biggerer
So, what do you think?
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skodaman
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| posted on 17/10/05 at 08:36 PM |
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I know many people don't even fit them but the stays supporting the hoops look too narrow a diameter if drawn to scale. Nice software
though.
Incidentally does anyone know how high the roll bar needs to be for a 6' 2 driver cos I'm trying to get one from a Westfield that is
330mm I think.
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CommanderAce
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| posted on 17/10/05 at 08:39 PM |
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yeah they are a little, but as I say its not final.
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paul v6
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| posted on 17/10/05 at 08:41 PM |
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I like it!! Very modern and stylish
Paul
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CommanderAce
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| posted on 17/10/05 at 08:43 PM |
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thanks bro, I'll licence the design for you at a reasonable price!
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Hellfire
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| posted on 17/10/05 at 09:04 PM |
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Looks similar to the design I had in mind for our next build 
Phil
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andygtt
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| posted on 18/10/05 at 04:57 AM |
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Very nice looking, I would have had that design on my indy if it had been available.
Well there may be an opertunity to have a few made rather than a one off.... I can recomend a place in Woking that can roll and bend which is what
that looks like it will need.
Andy
please redefine your limits.
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Fred W B
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| posted on 18/10/05 at 05:53 AM |
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I don't know if you will find someone who can do that tight bend on the one side, or is it a welded elbow?
Cheers
Fred WB
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CommanderAce
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| posted on 18/10/05 at 07:42 AM |
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well, I has hoping it could be a single piece rather then a welded elbow. I'll have to do some research. Thanks for the comments so far
Pete
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Fred W B
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| posted on 18/10/05 at 08:45 AM |
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Yes, find out what radius bends you can get done, and work from that, rather than the other way round.
While a lot of places say they can bend tube, not many can put a nice mandrill bend into a pipe with a sufficent wall thickness to make a roll bar
Cheers
Fred WB
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britishtrident
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| posted on 18/10/05 at 09:51 AM |
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Do you want a honest answer ?
A chocolate teapot would be more effective and look better.
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Mad Dave
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| posted on 18/10/05 at 09:57 AM |
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quote:
A chocolate teapot would be more effective and look better.
I think thats a little harsh
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James
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| posted on 18/10/05 at 10:05 AM |
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I like the look of it in that picture but as non-triangulated 'squares' you're asking for them to be significantly less effective
than they could be. In a high-velocity impact (which is when you want the roll-bar!) they'll tend to fold/break at the upper corners.
I do like the 'look' though! 
Cheers,
James
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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paul v6
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| posted on 18/10/05 at 12:52 PM |
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quote:
Originally posted by britishtrident
Do you want a honest answer ?
A chocolate teapot would be more effective and look better.
Have you ever said anything positive on this forum??
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CommanderAce
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| posted on 18/10/05 at 05:03 PM |
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Well bt, Donkervoort seam to think it looks better than a chocolate
teapot, as it was their J25 that gave me the idea.
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CommanderAce
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| posted on 18/10/05 at 05:07 PM |
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Thanks James, I'll see what I can do with the design; maybe modify it so there is more strength in the corners. Think I'll run it through
some stress analysis simulations so what it comes up with.
Cheers
Pete
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kb58
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| posted on 18/10/05 at 05:09 PM |
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The main shape is good. Instead of running the support all the way to the bottom of the rear frame, run them to the top corners of the rear frame.
And bulk them up - they prevent the main hoops from folding over backwards and what's there is nearly useless.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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CommanderAce
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| posted on 18/10/05 at 05:21 PM |
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quote:
Originally posted by kb58
Instead of running the support all the way to the bottom of the rear frame, run them to the top corners of the rear frame.
You mean here?
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kb58
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| posted on 18/10/05 at 05:59 PM |
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Yes. I'm making the assumption there'll be a corner tube down to the bottom, and the whole thing covered with a sheet and riveted. If
the corners are to be radiused that won't be strong enough though.
Another way is run them straight back and down to the same tube instead of the corner, then run tubes down the back, connecting the upper and lower
rails.
Regardless, you have to rivet a sheet on the area to get enough strength... and even then I worry about it buckeling. Anyhow, it's better then
running a tube directly all the way to the bottom rail - it'll buckle with very little force.
[Edited on 10/18/05 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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britishtrident
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| posted on 18/10/05 at 06:52 PM |
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quote:
Originally posted by Mad Dave
quote:
A chocolate teapot would be more effective and look better.
I think thats a little harsh
I'll re phrase it -- a chocolate teapot mounted on a skyhook.
The dictum is form follows function -- a roll over bar should protect the occupants in the event of shunt it dosen't exist to give a false
sense of sense of security, lets leave that kind of stuff to the little boys that play midnight burn ups with LED adorned Vectras in Sainsbury cark
parks.
The concept of a Sevenesque car is pure minimalism -- small light weight car making the best use of every gram of metal and rubber.
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JoelP
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| posted on 18/10/05 at 07:06 PM |
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quote:
Originally posted by paul v6
quote:
Originally posted by britishtrident
Do you want a honest answer ?
A chocolate teapot would be more effective and look better.
Have you ever said anything positive on this forum??
without sounding harsh myself, i can tell you ive read nearly all of tridents posts, and rarely are any anything other than constructive.
I dont think its ugly, but its not as strong as it could be.
Beware! Bourettes is binfectious.
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Winston Todge
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| posted on 18/10/05 at 07:38 PM |
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Great bit of CAD work there Commander!
I'm not going to be saying anything constructive about the roll bar but I must say it certainly looks slick!
What are the pros of SketchUp compared to other CAD software? I like the ability to add a light source and the resultant shadows. It looks much
tastier on the eye... 
Chris.
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CommanderAce
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| posted on 18/10/05 at 07:39 PM |
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Well if you want to be constructive how about some advice rather than just slating it...........??
I'm just a software engineer, not a mechanical engineer and my experience in this area isn't as great as that of you folk. The book
doesn't go into much detail about roll bars hence asking for advice from people I hoped could help me out.
Pete
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CommanderAce
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| posted on 18/10/05 at 07:41 PM |
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quote:
Originally posted by Winston Todge
What are the pros of SketchUp compared to other CAD software? I like the ability to add a light source and the resultant shadows. It looks much
tastier on the eye...
Thanks, well SketchUp was the first CAD software I used as I've stuck to it, I'm just about to have a play with Pro/Engineer, I'll
let you know how it compares once I'm ready
Cheers
Pete
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paul v6
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| posted on 18/10/05 at 08:02 PM |
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As a mechanical/design engineer I agree its not braced well enough, but quite a few I've seen look less affective. It does look classy though
and If your going to spend hundreds of hours and thousands of pounds on a car I want it to look as well as it goes!!
Paul
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