alright , since i completely missed the poll button , ill delete the other thread and you can re vote :

Now for ever who said it wont be too cheap : dont count yer chickens before they hatch . ill leave the price out - i want people to vote on wether they would buy one and have no misconceptions about driving a GRP/kevlar/carbon tub about .

Bugger, just finished typing a reply.


I think a monocoque setup could work very well indeed. However i would have concerns about the resistance to damage, it's a few years since i looked at this stuff in any detail (and then it was in push-bike frames)

My worry would be that if you did get a nasty gouge in the tub that it could affect the overall structure massively, also it would be very difficult to add/remove parts or to make customisations.

The beauty of a steel spaceframe is that any muppet can pick up a welder and add bits, change stuff around and even make the whole lot themselves, you can't do that with CF.


I think it's almost like comparing C4 to gunpowder.

C4, you can do what the hell you like with, even burn it and cook over it safely.

Gunpowder is safe in the right conditions, but can get very dangerous very quickly.

if it gets damaged , send it back to the factory for repair !!

it wont be completely carbon - a mixture so that its cost /strength all lay within acceptable parameters for the home builder . Although you wouldnt be able to change the physical dimensions so much, i believe its easier to adapt than you might think .

as an example , the lanes Darrian had an off at about 90 mph , took most corners off the car , we stook it back in the mold and repaired it , a week later he was running again , and that was extensive damage . like i said in the other thread
http://www.locostbuilders.co.uk/viewthread.php?tid=19993 there will some steel in the shape of a roll cage and front an rear chassis sections that will be the same as book dimensions or +4

I would not be too concerned as long as the design has some modular design to it. It would be nice to have a bolt together chassis that can have the major components replaced instead of having the entire tub ect replaced.
Dale

Extreme is a stainless steel tub and been around for a good few years now so nowt new there.

well , the point is , its a composite monocoque , im well aware its been done before , and shall be done again .

Who voted for Steel performs better? Dark ages of motoring history.

At least me...
As "performs beter" I don't mean steel is lighter or stronger but I think in the case of a Locost or related it gives some advantages: easy to built, repair or mod, cheap, afordable calculation if you want to optimize etc.
How much will carbon be lighter and stiffer?
For my car I will probably use a mid way solution: a steel frame with aly sandwich paneling around the cockpit cell.
Square tubes of 25 with inside and outside 1.6 (or even 1.2) paneling, with a 25 thick honneycomb core between both panel.
The honneycomb weights nothing and it can make even a thin sheet become structural.
As anyone used this solution?

Nobody has mentioned an aly monocoque. There aren't many about and I don't think Robin Hoods' idea has really proved that its a good concept very well!
Mr. Chapmans monocoque F1 cars were constructed in aluminium and these proved rather affective.

In my archive are a few pictures of an aly chassis. Other than a small front and rear subframe and suspension pick-up points made from steel it is all constructed with sections of folded sheet aly. The sections are then riveted together with Araldite on all joints. In my opinion this method is a lot easier to get true than a spaceframe. Construction is also very quick to build, unlike a composite chassis and above all, VERY light!

I admit that for the purposes of a locost if in regular use on the road could, be susceptible to problems with fatigue. There aren't many front engined monocoques around either. They are generally mid engined cars with the engine as a stressed member or engine/box/rear suspension on a seperate subframe. But with some thinking a front engine design could be achieved.

Andy

[Edited on 12/12/04 by andylancaster3000]

well , its true that it may be easier , but a composite chassis can be just as easy to build - i shall attempt to prove that . I dont think an all ally monocoque is any lighter though - to a comparable strength , my intention is still to have a full roll cage anyway .

Sorry, i didn't mean for it to say that it was very much lighter then a composite chassis but for its weight, I think it would be considerably stiffer then a spaceframe

Andy.

id agree with that , although im a little apprehensive about driving a pop riveted bit of ally about , that really does suit racing cars more - imagine all the deburring youd have to do aswell . of course ally is safer than steel for the same strength since it has a higher yield strength . Once a mold is made , you build it without a single seam or join , which also contributes to strength .

That composite chassis idea sounds interesting. Would you bond in steel lugs for the major components then or would you try something fancy with the mould?

I would agree with your concerns about driving the riveted chassis on the road. However the car in my archieve raced many seasons without a hint of rivet failure, but that was with high quality rivets (about 2000 of um!)

Andy

yeah , i shall be bonding in attatchment threads/lugs where necessary , some will be dowelled to allow removal/replacement etc .

At the momnet still designing/sketching wether it would be possible to have the whole chassis as composite without the need for the front suspension subframe .

quote:

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Originally posted by andylancaster3000
There aren't many front engined monocoques around either. They are generally mid engined cars with the engine as a stressed member or engine/box/rear suspension on a seperate subframe. But with some thinking a front engine design could be achieved.

Andy

[Edited on 12/12/04 by andylancaster3000]

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What about Lister Storm ?- could you consider a marcos for mocoque , not truely 'composite' , but a monocoque chassis of sorts.Maybe i shouldnt define it as monocoque - merely composite chassis ?

What is the exact definition of monocoque? From my understanding nearly every road car chassis falls under the definition of monocoque!

One of the best, most developed, composite chassis I have come across is the GTM chassis. I was quite suprised with how little metal is the the chassis but they assured us of its strength with 20 years of development in it!

Andy

quote:

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Originally posted by Volvorsport
...... . of course ally is safer than steel for the same strength since it has a higher yield strength .

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mon·o·coque n.

A metal structure, such as an aircraft, in which the skin absorbs all or most of the stresses to which the body is subjected.

higher yield strength - if ive got this correct is when the material has gone beyond its plastic range (deformation) , ally take a lot more energy to "yield" , therefore in an accident it absorbs more energy from the crash ,protecting the occupants better than say something of the same structure in steel . Thats why those deformable structures ( ie ally radiators) at the front of such speciall vehicles do there job admirably .

After the locost club meeting last night im getting some really supportive comments - so keep em coming .

quote:

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Originally posted by Staple balls
mon·o·coque n.

A metal structure, such as an aircraft, in which the skin absorbs all or most of the stresses to which the body is subjected.

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i dont think it has to be , of course when that description was about - it probably only applied to metal structures

quote:

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Originally posted by Volvorsport
i dont think it has to be , of course when that description was about - it probably only applied to metal structures

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well , i know the citreon was early , but the lancia in1924 was the first of any monocoque design .

quote:

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Originally posted by Volvorsport
well , i know the citreon was early , but the lancia in1924 was the first of any monocoque design .

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Sorry to be a bit late, but I voted for the monococque.....
But then I would I suppose.
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There are only two pieces of steel in the monococque, the upper seat belt mounts and they are about 2" square.

The Clan Crusader was a GRP monocoque that only had 2 sections (upper/lower) as opposed to the commonly used 3 section manufacture.

Very easy to do and was far and away more torsionally rigid than any other sports car of its era.

The yield point is the point at which the material will go into plastic (permanent) deformation. Up until then it is considered elastic. After reaching the yield point, a materials properties radically change and its ability to withstand an impact force decreases.

Cant explain it properly except to say that deformation increases up to fracture with a reduced force after the yield point is exceeded. So, you put a load on and get to the yiepd point(graph gradient over 45degrees on Load vs Extension graph). Increase the load by a small amount and the extension goes up by a large amount (graph grad very low)

Monocoques also tend to be more forgiving in a crash as they have a tendancy to fracture/ tear rather than buckle like a spaceframe does. On the Circuit of Ireland years ago an Irish Clan pushed the B pillar of a sunbeam talbot to the tranny tunnel and had hardly any damage to teh corner that hit it...

By contrast, a Lotus elise chassis is considered a writeoff if any part of the chassis is buckled!

Ah the plot thickens, so what u intend for the composite, 1. Carbon and Carbon/kevlar, or 2. Carbon/kevlar and cross strand uni directional Cloth oh wise one. Wanna hand?
Shug.

hmm , what materials have you got spare from a big contractors job ?

Id like to know if you think a darrian is stronger than a clan - since ive seen clans after accidents and ive also seen plenty of darrians / repaired em.

couldnt honestly tell you. Though I have a Clan that was rolled/cartwheeled when flat out and suffice to say that it is still square and my spare screen fits in the hole still... 300 hours of body repairs amd (mainly sanding) ~ never again will I rebuild the front corner on one from a Tesco bag

then went and bought another shell lol...

What would you say volvorsport? I would guess a modern T90 is tougher but probably only due to its size,integral steel cage and loadsa carbon/kevlar. Were Clan about today, I reckon that they would be further ahead imho.

What sort of monocoque are you planning. Would be very interested in discussing it further if you want as its my field of interest anyway

quote:

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Originally posted by Volvorsport
as an example , the lanes Darrian had an off at about 90 mph , took most corners off the car , we stook it back in the mold and repaired it , a week later he was running again , and that was extensive damage .

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well , it will be 90% composite with a subframe at the front for the suspension , the rear will have a cradle for suspension .

My crux at the moment is designing where the subframe/ tub meet to be stiff . Im only going this route since a full monocoque will take space away from engine bay - and thus reducing potential donors . Anyway , its being designed as we speak .

I know the darrian has been tested for stiffness , and i can say that its quite stiff - and that only had one layer of kevlar (450g) - to say that its full of carbon kevlar is wrong since they have quite a thick laminate and a full FIA cage .

A TUB (e) version has subframes front and rear .

And after hearing about clans that used paper rope for a roll cage , and then the windscreen would pop out , tearing the roof back , i know which one i prefer .

I dont think a book chassis would survive well enough to merit repair , if it had an off like the lanes did .

quote:

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Originally posted by Alan B

quote:

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Originally posted by Volvorsport
...... . of course ally is safer than steel for the same strength since it has a higher yield strength .

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Erm...?
What does that mean?

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well , if im explaining it correctly , the point at which ally becomes plastic -ie above the elastic range (deformation) is a lot higher than steel . i did say strength for strength basis so that would probably mean more thickness /weight . Thats why ally chassis arent as popular since they need to be heavier to be as strong as the steel variant .

The upshot is tho that ally will protect you more in an accident .

If using Ally, there are other aspects to cosider too. How do you go about creating your monocoque? The Yield point in the welded area of Alumium drops to less than 50% meaning that you may as well use steel. Glueing/bolting/riveting are the only practical methods and even those have their limitations ~ how many rivets would you ahve to use:

The paper cage was a rush job for teh Manx in 1972. They needed a cage and it met the rules of the day. It was tested by putting the car on its roof, then putting a skip on its floor and filing with water to the required weight...

From what I have been told the screens really only pop out when people have not prepared/built their cars properly and this has caused problems.

I have 2 clan shells, both of which have been sucessful on rough surfaces (forrest stage and rallycross) back in the 70's/80's and in both cases have yet to loose a screen!

Interesting to hear that they only have one layer of Carbon. I thought that Tim Duffee had mainly used it on them. Learn something every day.