turbo time
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| posted on 15/10/05 at 05:48 PM |
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Unibody Locost? Anyone build/design one?
Since I've got nothing here at school to get my hands dirty, I've just gone into thinking mode.
I was wondering if anyone had designed and/or built a Locost of unibody construction? Tube chassis are so labor/time intensive and really a pain in
the ass to build. I have all sorts of crap jotted down on napkins and in my head at this point. I don't know how workable they are, just
concepts at this point, but after looking up some weights, I estimate would be no more than 25 lbs heavier than a book chassis. I'm just on here
fishing for ideas and information.
The advantage...well, you'd just need your MIG welder, a home-made sheet metal brake, a good cutting tool (plasma cutter might almost be need
rather than a want in this case), and you could make a chassis in a few hours, as opposed to days (or weeks). Then, the fiberglass body work, such as
nose-cone, engine cover, wings, etc, would go on top as normal.
Again, I'd say the main advantage here is simply construction/time, (cost would also be marginally less). You could likely get a unibody to be
significantly more rigid than the tube-chassis as well, but lets not go into that yet because I have nothing drawn-up in inventor to test. Also, from
what I've drawn up, I'd say designing proper suspension using all sorts of available mass produced hubs/spindles, feeding forces into a
unibody as opposed to a tubie, really opens up the door in terms of placement of control arms, shocks/springs, rockers, etc...
...Thoughts?
[Edited on 15/10/05 by turbo time]
The Projects: www.absurdcars.com
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Triton
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| posted on 15/10/05 at 05:53 PM |
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I take it you mean a monoque then....grp or ali or heaven forbid carbon fibre?
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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turbo time
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| posted on 15/10/05 at 05:55 PM |
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Nope, sheet steel, like 90% of the modern passenger cars out there.
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Triton
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| posted on 15/10/05 at 05:56 PM |
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Wouldn't bother......cost a fortune then rot anyway
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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Triton
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| posted on 15/10/05 at 06:32 PM |
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Tescos do their own cornflakes....but doesn't mean they are better than kellogs cos they are cheaper
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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big_wasa
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| posted on 15/10/05 at 06:41 PM |
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Ive sat in the light weight and it seemed a well made car...Loads of room...
Well compared to my m8's sub-K that is
If they had surplied it as they had intended . ie the locost way bit by bit, and not just a complete kit . I for one would have had a go at it.....
To build a RH is a case of "making good" and not just bolting it together...
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Triton
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| posted on 15/10/05 at 06:49 PM |
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Just being daft sorry...
Given the choice i would have the Quantum Extreme.
Cheers
Mark
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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Taz Surfleet
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| posted on 15/10/05 at 11:03 PM |
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The lightweight originally was supposed to be available as a set of sheets to be rivited together etc, they seem to have lost that idea and have
decided to sell it as a complete kit at £1795 + VAT which doesnt sound very locost to me !
However if you were to take a set of locust plans you could use these to make a unibody, making the necessary adjustments to allow for stiffners and
suspension mounting areas as required.
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iank
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| posted on 17/10/05 at 02:22 PM |
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Well as usual with RH you get a lot of bits for your money, so the price is pretty locost for a kit.
http://www.robinhoodsportscars.com/contents_lightweight.php
It's a nice idea, but I'd be worried about the longevity of the suspension mountings. (punched ally tubes IIRC)
From their pictures I'd say it was prettier than the quantum.
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Volvorsport
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| posted on 17/10/05 at 02:38 PM |
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almost , i bonded a kevlar tub into my chassis , i was experimenting with a complete composite one , but trying to get the space/strength cost right
was a major headache , so i opted for the intermediate idea .
im not sure if such a beast is really practical - you need a lot of space at the front , you might decide that spaceframe is actually easier in the
long run , especially when it comes to mounting suspension brackets and other stuff you just havent thought about .
www.dbsmotorsport.co.uk
getting dirty under a bus
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Fred W B
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| posted on 17/10/05 at 03:33 PM |
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The 7 looks like it does because it was originally designed to be made from tubing.
The big holes left for the people and engine to be inserted into the car are the problem.
It would be best to start from somewhere else if you want to design a monocoque chassis.
Cheers
Fred WB
[Edited on 17/10/05 by Fred W B]
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rug
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| posted on 17/10/05 at 04:29 PM |
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quote:
Originally posted by Taz Surfleet
The lightweight originally was supposed to be available as a set of sheets to be rivited together etc
Rivit together a chassi?!  Wouldn't that rattle itself apart after a while?
/Carl
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kb58
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| posted on 17/10/05 at 05:09 PM |
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That's how many racecars were constructed, and even aircraft.
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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turbo time
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| posted on 17/10/05 at 10:34 PM |
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Ah, thanks for that info. The quantum chassis shown on their webpage is nearly exactly the image I had in my head, although they do it in stainless,
very nice. There don't seem to be any photos of the RH chassis, though that price (IMO) actually does seem really locost, being that people can
easily spend twice that if they aren't paying very close attention. (Then again, I don't know how much more that VAT ends up tacking on).
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kreb
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| posted on 17/10/05 at 11:50 PM |
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Monocoque certainly has it's appeal, but it's trickier than it looks. The whole load distribution isn't as intuitive as a tube
chasis, and a poor design could literally fold up on you.
That said, as an owner of a sheet metal shop, the idea of a chasis that I could program into a CNC plasma cutter is pretty appealing. You could have
all your alignment points built-in so that once it's cut and formed, it could "tinker-toy" together. Dimensionally perfect with a
minimum of jigs. Nice!
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iank
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| posted on 18/10/05 at 07:43 AM |
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quote:
Originally posted by turbo time
...
(Then again, I don't know how much more that VAT ends up tacking on).
17.5%  (but not if it's exported, they you have to pay whatever import duties apply)
On the subject of racecares and boats, yes they have used this form of construction since WW2.
However I believe aircraft use better spec aluminium and definately don't use pop-rivets (which is what I bet most people who build a
lightweight will use), while racecars don't have anything like the number of running hours put on the chassis and will usually be run on smooth
tracks.
Both will get closely inspected for cracks far more frequently and professionally than 99% of kitcars.
I don't think anyone knows for sure how it will work out long term in kitcars since no-one has tried it before. Hope it works out for them
[Edited on 18/10/05 by iank]
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Fred W B
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| posted on 18/10/05 at 08:42 AM |
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I read a kit car magazine article on the Quantum extreme last night, that says the stainless tub has 3200 NM/deg (=2360.195 ftlbs/Deg) torsional
stiffness and weighs 100 kg! so not very impressive -
the Uprated "cymtriks" spec is quoted as - 2540 ftlbs/Deg, 78 kg
Cheers
Fred WB
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MikeP
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| posted on 18/10/05 at 11:38 AM |
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If you're scratch building a locost I think you'll find buliding the tube chassis is the quickest and most fun part of the build -
it's the rest of the bits take forever. You might save a tiny part of the overall build time using a unibody if you've have a proven plan
or perhaps a significant amount if you're putting together a kit.
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crbrlfrost
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| posted on 19/10/05 at 02:11 AM |
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Aircraft usually use solid rivets where possible and things like CherryMax rivets where they muct rivet blind. It is a known fact that race cars do
get loose after a given amount of time and need to be rebuilt, usually involving lots of rivet drilling and upsizing to the next available size. I
don't think there is a lot to be gained by building a moncoque 7 given the overall weight of the vehicle and relatively small forces thus
encountered. I think the shear panels normally attached could be used more effectively through bonding and proper rivet design, and that may yield
further gains in addition to cymtiks analysis at a minimal weight penalty. Anyway, happy building!
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