Hammerhead
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| posted on 2/12/06 at 04:00 PM |
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Mr Ed,
That chassis looks like a good design. Did you use solidworks?
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mr_ed
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| posted on 2/12/06 at 05:15 PM |
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Yup. Nice package!
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designer
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| posted on 2/12/06 at 05:33 PM |
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Far too complicated and expensive to make.
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nasty-bob
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| posted on 2/12/06 at 07:29 PM |
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Looks like you've been busy Mr. Ed
Did you design the uprights? they look like ADR 1000 ones to me.
Good to see someone having a bash
Nice one!
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mr_ed
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| posted on 2/12/06 at 08:51 PM |
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Well spotted! They are indeed ADR uprights.
As for difficult to make, it is actually very easy. As the tubes are all laser-cut they all have castellations in the ends, and corresponding slots
where they mate to other tubes. It all slots together and to a large extent self-jigs. And the only fibreglass on it is the engine cover.
So in my books it is easy to make, and wouldn't cost any more than any other 7-alike.
[Edited on 2/12/06 by mr_ed]
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TheGecko
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| posted on 3/12/06 at 12:30 AM |
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quote:
Originally posted by mr_edAs for difficult to make, it is actually very easy. As the tubes are all laser-cut they all have castellations
in the ends, and corresponding slots where they mate to other tubes. It all slots together and to a large extent self-jigs. And the only fibreglass on
it is the engine cover.
So in my books it is easy to make, and wouldn't cost any more than any other 7-alike.
Well, that assumes that the builder has easy and cheap access to laser tube cutting, CNC mandrel benders etc. That is NOT comparable to a Locost
chassis built out of straight lengths of 25mm SHS.
I'll also agree with Pete's comment that there seems to be a lot of decorative tubing in the chassis. I won't even start on the
wisdom of curved (AKA pre-failed) chassis tubes.
Still, each to their own and, as my chassis (Mk2) is still mostly welded sub-assemblies or loose tubes scattered around the workshop, I'm really
in no position to criticise anyone 
Dominic
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russbost
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| posted on 3/12/06 at 04:12 PM |
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quote:
I won't even start on the wisdom of curved (AKA pre-failed) chassis tubes.
So, the Atom chassis has "failed" as have all of our roll bars!! Don't remember that from my college days.
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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TheGecko
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| posted on 3/12/06 at 10:24 PM |
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quote:
Originally posted by russbostSo, the Atom chassis has "failed" as have all of our roll bars!! Don't remember that
from my college days.
The "pre-failed" description for curved chassis tubes originates with Colin Chapman. In a pure space
frame tubes should only be loaded in compression and tension - a bent tube has already started to fail under a compression load. Deliberately loading
a bent tube axially and then expecting it to be stiff is not good engineering. A roll bar is not a space frame (at least none of the ones I've
seen are).
Dominic
[Edited on 3/12/2006 by TheGecko]
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flak monkey
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| posted on 3/12/06 at 10:37 PM |
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Curved rails in a space frame are a really bad idea if you want torsional rigidity in a struture. The atom gets away with it because it is a
combination of tubular and monocoque construction.
All memebers in a spaceframe should be loaded in pure tension or compression, by putting a bend in the tube you convert this to a bending moment,
which tries to bend the already bent tube even further. If you want to use bendy tubes as decoration, make them no strutural and thinwall aluminium.
But its not a brilliant idea (from a performance point of view) to use bendy tubes as a strutural member.
Nice design, non the less, and it will work, just dont expect a particularly rigid chassis at the end of it, or at least one which is not as rigid as
it could be.
David
Sera
http://www.motosera.com
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Kamikza
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| posted on 3/12/06 at 10:37 PM |
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Hm beter build an atom ant this formula 1 stile spoilers ar making it wery hm not cool for me at least
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nitram38
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| posted on 3/12/06 at 10:59 PM |
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Looks like wembley stadium is in trouble then
There is no monocoque in an atom. The floor pan is just a fibre skin that keeps your feet dry.
Chassis upside down:
Close up of seat mounts:
Floor "tub" :
[Edited on 3/12/2006 by nitram38]
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akumabito
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| posted on 3/12/06 at 11:29 PM |
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I like the design, but it seems either too tall or too short..? Either way, the proportions look a bit off to me..
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kb58
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| posted on 4/12/06 at 01:03 AM |
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I agree about the bent "pre-failed" tubes. However, if two bent tubes are in parallel, and diagonals added between them, I think and
disadvantage goes away.
BTW, try finding a table for bent tubes in a strength of material text book. It would be hard to find. As others have said, a bent tube is MUCH
weaker than a straight one, so you have use a bigger, heavier tube to make up for the bend. Or, do as the Atom did, basically making a bridge truss,
which is very strong.
I'm annoyed I didn't come up with the Atom chassis design. It's brilliant.
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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nitram38
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| posted on 4/12/06 at 06:20 AM |
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If a bend is weak, then why throughout engineering are all supporting structures curved?
Look at any bridge or archway.
Careful design can make curves stronger than straight material.
For instance, take a piece of square box and bend it over your knee, then try the same with round tube but with a curve.
I am now going to suggest you try to bend it against the arch and not in the same direction as the curve.
As long as both ends are held with something so that they can't spread, the arch is stronger than flat box and can be loaded up more in that
plain.
Take two opposing arches and brace them so that they oppose each other, and you now have a stronger structure than two parrallel straight box
sections.
Think about bridges and you will understand what I am saying.
Hope that all makes sense!
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Doug68
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| posted on 4/12/06 at 08:07 AM |
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On the design. I don't like it for various reasons, mainly it looks like cad design gone mad. I think if you keep going with it though it will
get better. I've restarted my design more times than I can remember and each time its got better.
On bent tubes. Axially in compression bent tubes are useless its as simple as that.
If you look at the stadium or the atom you will see that the curves are of sufficient radius that the elements between the nodes on the triangles can
be considered essentially straight.
The other thing is Architects and car designers draw whatever stupid shape they want (Pontiac Aztek fro example) and then a room full of Engineers has
to actually make it work.
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mr_ed
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| posted on 4/12/06 at 08:36 AM |
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The bent tubes are basically just cosmetic on my car, as you can see it still has a substantial chassis even without the upper banana rails and the
sidepods. Thought about making them out of 20gauge steel but found the weight saving from doing so was less than a couple of kgs.
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Peteff
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| posted on 4/12/06 at 10:05 AM |
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Cosmetic as in unnecessary?
Leave them out then and save the weight, that's the idea of sports cars isn't it?
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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mr_ed
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| posted on 4/12/06 at 11:10 AM |
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Like I said, I dont expect it to appeal to everyone, but I feel you're somewhat missing the point!!
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Doug68
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| posted on 4/12/06 at 01:21 PM |
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Conversations here tend to wander off of the point I've found, only having been here a few weeks myself.
To respond to your poll, too me it's uncool I think the whole road going formula car thing is just never right aesthetically.
Please feel entitled to rip lumps out of my design when I get balls enough to post it all.
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russbost
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| posted on 4/12/06 at 10:57 PM |
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Sorry to be "off thread", but I'm with Nitram on the bent tubes thing. Strongest 2d structure is a circle & strongest monocoque
is a sphere. I think the problem here is that too many people have spent too long with CAD programmes & think that means they could actually
design something!!
Anyway, back to the thread, how can the whole roadgoing Formula thing be wrong aesthetically - I could produce a car which is an EXACT copy of a
current F1 car (within mm) & make it roadgoing - would that be "aesthetically wrong"?
At least Mr_Ed has had the cojones to design something for himself rather than following the herd blindly like many do!
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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nitram38
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| posted on 4/12/06 at 11:23 PM |
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Design is compromise.
Whenever you design a car, there will always be some sort of "fault" that cannot be ironed out.
Designers have always looked for the "perfect" car.
When you actually design and build a car, there will always be some one who will poo poo the idea.
My car is not a 7 and for a few reasons ( not bashing them in any way! ).
Firstly the design has been around 40 years and this is the 21st century (perhaps a few more improvements needed even if it is aerodynamics).
Secondly there are too many of them and the resale value is a lot lower than they cost to build (most of the time).
Thirdly, people hardly notice them now along with porches etc as they are common place.
I appreciate that a locost builder has to be more inguinuitive than the catering van brigade and that is why I am a member here and not on
blatchat!
Innovation takes guts, commitment and money as you might have to do things 2 or 3 times to get it right.
I know that people want to build their own car and the book locost is an ideal start, but some people have moved on from the building of someone
else's design and want to build something truly unique.
Go for what you want Mr_Ed. You are the only person that you need to satisfy.
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Doug68
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| posted on 5/12/06 at 12:00 AM |
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I agree completely with the last post, really the only person who needs to like it is whoever's building it (unless of course you want to sell
it).
Personally if I were driving around in a F1 or any other formula replica on the street I'd feel like a complete arse. But thats just me.
The nature of this forum is we're all doing are individual thing and one mans vision is the next guys pile of poo, and whatever you or I create
we cannot expect universal acclaim for.
Individuality is great, when you see something you don't like it's confronting, you should think about why you don't like it and
learn from that.
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TheGecko
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| posted on 5/12/06 at 02:25 AM |
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Two comments:
- Absolutely agree on the personal preference issue. At the end of the day most of us here (particularly in the mid-engine forum) are building for
ourselves rather than having to meet the (lowest common denominator) desires of a customer base. If you're building something that satisfies
your desires then other people's aesthetic opinions are neither here nor there. Structural/engineering advice is something else however.
- Bent tubes per se are not a problem. Bent tubes in a space frame are. A true space frame should have all members loaded only in
compression and tension. By extension, that means straight elements between nodes and all loads applied and reacted through the nodes. Yes, curves
can be very strong - just not in a space frame.
The Atom is a quandry. It looks absolutely fantastic and it obviously goes very well. I suspect they get away with a lot by using quite large
diameter tube for the longerons and fairly large bend radii which results in almost straight loads paths along the truss work. Would it be stiffer if
every curved section was replaced with a straight one? Maybe (although there'd be a lot of extra welded joins which might reduce the overall
stiffness and would certainly make it slower to build). Would it look as good? Almost definitely not  Is it an acceptable engineering compromise?
They seem to have no trouble selling them and no-one is complaining about the performance
Dominic
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russbost
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| posted on 5/12/06 at 09:08 AM |
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I think there is a fundamental misunderstanding here.
I agree a true spaceframe should be built from straight tubes. A true spaceframe would not need welding & could simply be pinned together by a
bolt at each joining point (I believe that is basically the definition of a "true" spaceframe). However none of us are building true
spaceframes - because we are welding each joint this changes the nature of the structure as a whole, making it far stiffer, & in this situation
bent tubes are not (necessarily) a problem. This is why the Atom design is stiff & works well.
If you took an upper & lower chassis rail, both straight, & welded in a series of circles along the length (bit like the Audi badge, but with
the circles touching) this would be extremely strong, but the only straight tubes would be top & bottom.
Back to the thread, I'd like to see Mr_Ed's car on the road!
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Alan B
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| posted on 5/12/06 at 03:08 PM |
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Interesting debate, and one in which I have some extreme interest (see other thread).
Whoever used the word compromise was dead right. Yes, in pure spaceframe theory bent members are a no-no, but in reality, with welded joints (as
mentioned) and numerous diagonal members which effectively create pseudo-nodes (cool made-up expression huh?) (also as mentioned) the picture is not
so clear.
I'd guess the key factor would be the amount of offset from centre line between psuedo-nodes relative to the tube's buckling strength (Mr
Euler anyone?)
I know that when I have finished mine there will be only small amounts of curved offset (chord?) between my nodes (real or pseudo)...
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