Vehicle Development Project - Interests

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Richied76
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Re: Vehicle Development Project - Interests

Post by Richied76 » Sun Dec 12, 2010 7:41 pm

I think if you were construct a monocoque with the main structual parts of birch and the rest of pine ply, you could cut the weight while keeping strenght. The only worry i would have is where the fiberglass meets the pva wood glue in the corners. You would either have to clean the whole timber frame with acetone before and then lay up over the top of it OR use an expanding vinylester wood glue. I use a product when constructing stair strings thats so strong that it can soon take the edge off of a tungsten tipped rounter cutter. I'll find out the exact name of it at work tomorrow. As for willow, you really need to hold its moisture content below 5% or kild dry it.

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Wed Dec 15, 2010 4:15 am

Pine is an interesting suggestion. Come to think, i haven't heard of pine being used much in non-furniture cases. But it does have a nice density when prepared.
I'm curious about this product you mention. I've read similar enthusiastic declarations on the subject of West System epoxy in boatbuilding.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

Carlos
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Re: Vehicle Development Project - Interests

Post by Carlos » Wed Dec 15, 2010 6:33 am

Pictures of a simpler Marcos chassis, 3mm marine plywood, looks like mahogany to me, using epoxy glues, these pictures are reproductions of the original Marcos, note construction, spaceframe-subframes front and rear, centre section wooden monocoque, the whole site is worth spending some time, perhaps they would offer a few tips:

http://home.swipnet.se/~w-90803/wooden.htm

Carlos
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Re: Vehicle Development Project - Interests

Post by Carlos » Wed Dec 15, 2010 8:47 pm

Also worth a look, the Splinter, an all wood 'supercar' project:

http://www.joeharmondesign.com/

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Wed Dec 15, 2010 10:28 pm

Those have been posted carlos. but worth looking at for anyone who hasn't yet. Joe's design of the core of the tub, with its torque tube and angled firewall is really quite stiff. And of course Costin, for anyone looking at tubs and "monocoque" chassis his work should be required reading along with the jaguar d-type. Hell while we're at it, anyone not familiar with the Miura chassis should go check that out too.

In any case we're going to have to be clever and simplify construction of the tub unless someone thinks it makes more sense to make just one car or ship large tubs around the world.
Think modular.
We can comfortably confirm, I think, a few things:

-We'll be designing around a system of a probably non-metallic tub with detachable subframes front and rear.
-There's a consensus building, if only tacitly because the idea is so cool, around using the Hartley H1v8. mid rear, longitudinal.
-competition target seems to be lmp3/hillclimb.
-2L class would suggest maybe TKD's 2L V8 instead though. pity there's so little online info, makes it harder to share this way.
there's an article in RCE 'this' month though.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Wed Dec 22, 2010 3:18 am

OK i'm working on some Autocad drawings of the pencil drawings you saw before.
'drag em into inventor and then i'll have something to present. In the meantime I thought a look at structural architecture is worth bringing up.
As some may have heard Caterham has said they'll be revealing something new in january. This threw me back to the days of the Reynard project. Back then they came up with this really clever, and simple structure that would remind you of the Elise, only in carbon, and for less money.

To mount the subframes I've been thinking along the lines of using dowels from the face of the firewall and foot of the tub. It has the potential for a great deal of versatility, and in the front allows easy changes of suspension architecture if done right. A thread from the Engine Transmission, Controls forum got me thinking about the suitability of the approach for what is in practice a privateer car.
I feel it can be made to work longer term but may require some ruggedizing.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

Carlos
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Re: Vehicle Development Project - Interests

Post by Carlos » Wed Dec 22, 2010 3:40 pm

Yes - Maybe also put in a layer of aluminum sheet as firewall and to distribute the loads. Notice - in the pictures I posted - very small steel hardpoint brackets connecting plywood tub to spaceframes. Sending a PM about material from the classis book on suspension and spaceframes Sports Car Chassis Design by Mike Costin - Which is currently out of print.

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Wed Dec 22, 2010 9:43 pm

Pretty much the best christmas gift i ever got over the internet!
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Thu Jan 06, 2011 10:08 am

While some of us have wood on the brain and i'm trumbling through making that work for us i thought i'd share the method the very famous Mosquito used. What they did was very clever in the days before Nida-Core. They produced a large curved surface with a lot of void between the outer skins very simply. They layed up the initial plies over a buck and then ran some structural spacers of ply and iirc balsa in some sections and then added the top skin. Pretty cool, and in principle easier to work with, at least if you have the initial mold. There's a lot of mileage yet in the principle, especially with the availability of endgrain balsa and higher performance glues.

Image

ok fine while we're at it there are some more recent ideas, in surfboards of all things.

Image

hah like i said earlier, can of worms!
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

marcush.
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Re: Vehicle Development Project - Interests

Post by marcush. » Thu Jan 06, 2011 3:25 pm

I just lovit! who needs carbonfibre when you got trees in front of your house?
There are marvelous veneers around..
=D> =D>

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Sat Jan 08, 2011 7:51 am

OK call me crazy, but i wandered over to the Engine etc forum here and something triggered a memory of Ilmor, which reminds me more often these days of their short time in Moto GP than it does F1 -so sad isn't it?- so on a lark i looked it up.
Ilmor is making their moto gp engine available for development work! It made me all excited!

There's one to put in the "how fecking cool would that be!!!?!!" pile; what with being a V4, 800cc and 215hp, pneumatic valves and only weighing 60kg with its built in transmission.

In other words, i'm keeping the firewall architecture as open as possible :)

Ilmor/MotoGP
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Sat Jan 08, 2011 10:14 am

I'm trying to sort out at what point in the operation to make it easy to assemble.
Still talking about the tub here, trying to maintain the optimum geometry and have as many people able to build/own the chassis as possible makes for an interesting thought exercise.

The trade-offs are a balance between skill of the builder, the tools he has available and the time you want to spend.

I know I can design the chassis to the optimum geometry, such that it could be built from scratch by a relatively unskilled person with not all that much tooling, but it would take any average joe, me included, a year to put together, it would require many many steps and be not quite as nice as if we could just hand the work over to someone already tooled up.
Next best option is to simplify the geometry, this would allow us to make the parts higher quality for a given amount of labour, but the issue then becomes a matter of stress at 90degree joints, a little excess weight, and the simpler chunkier geometry will under most uses of the car mean the aero contribution from the tub will be more an obstacle. I'd much rather build it so that the tub can stand on its own with the rest of the chassis and any really cool ideas you aero guys can think of will be open. Perhaps there's room there i don't yet see. And some options to work my head around to optimize the loadpaths and stuff that work out in our favour at this level of work in wood.
Next option is simplified geometry in carbon, this is nice, same problems as above but you do get to brag you've got a carbon tub, and it has the potential to be lighter. The cost at this level is probably comprable to the optimum-geometry moderate-work wood option, which again is nice. The other issue is that including carbon in the build does pose the question of curing.

Next question, which works into repeatability and therefore inter-compatability of subframes, pedalboxes, and sundry other solutions across the project; is whether it would make more sense to have the tub easy to assemble yourself, or build yourself.
The process for the carbon one would look like this: http://autospeed.com/cms/title_Building ... tml(scroll down to Making the Tub) and like this: http://dpcars.net/dp1v8/da.htm

beyond that we get into mold making.

here's some food for thought: Saleen S7 tub

The basic problem is compound curves, they're hard to execute well, but more than that, they're difficult to cut to. But obviously i want to be able to include compound curves, we'll get a stronger lighter structure out the other end.

So i'm going to hammer it around a bit more and when i've got the cad together i'll show you what i mean.
Last edited by humble sabot on Tue Jan 11, 2011 10:43 pm, edited 1 time in total.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Sat Jan 08, 2011 10:58 am

this isn't so far off the design speaking of the simplified geometry version of the tub:
http://beyond6000.blogspot.com/2010/10/ ... part2.html

the Strathcarron had an all alu tub, pretty cool, not exactly optimal but super easy to build from sheet.. essentially.

http://locostbuilders.co.uk/upload/a216 ... %20tub.JPG
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

humble sabot
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Re: Vehicle Development Project - Interests

Post by humble sabot » Wed Jan 12, 2011 3:56 am

Here's a really good discussion on team management, which is relevant.
http://fsae.com/eve/forums/a/tpc/f/8256 ... 810041/p/4
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

Carlos
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Re: Vehicle Development Project - Interests

Post by Carlos » Thu Jan 13, 2011 5:03 pm

Thanks humble sabot - good to see someone take the lead on this project. As far as basic dimensions, why not pick a favourite sports car for wheelbase and track?

If we need a common CAD software to use, I could recommend the free education version of PowerSHAPE-e. It's not only a CAD program, it includes modelling and rendering:
http://powershape-e.com/index.asp
http://www.powershape.com/
http://powershape-e.com/general/ps_draft.asp
http://powershape-e.com/general/total_modelling.asp
http://powershape-e.com/general/ps_render.asp