Aluminium monocoupes and kit cars
Discussion
I have been thinking about kit cars again and was wondering why to the best of my knowledge there are no build it your self aluminium monocouple design's out there? I know that robin hood had a go with the light weight witch does not seam to have gone well. Having said that in the US a number of aeroplanes are built from in kit form using this method so it can be done and I assume with a significant degree of safety that and access to cheap laser cutting, the idea of a flat packed monocoupe kit seam to make sense at leasest to me.
Blake
PS I have no idea of the correct spelling of monocope
Blake
PS I have no idea of the correct spelling of monocope
A couple of reasons are that you don't see traditional folded-and-rivetted aluminium monocoques (<<< correct spelling) are:
- they're very time consuming to build; lots and lots of holes to drill and rivet, so they're are much more expensive and labour intensive for a manufacturer to produce (and it would be difficult to offer a kit of pre-folded panels to allow the builder to do the time consuming bit, due to issues of jigging accuracy).
- They lose a very substantial part of their stiffness in regular use, due to the rivetted joins 'relaxing'. A typical 1970's aluminium F1 car would typically lose something like half of its stiffness over the course of a single season's race use, so you can imagine the impact (pardon the pun) of 60,000 miles over bumps, kerbs and potholes.
Edited by Sam_68 on Friday 5th November 23:41
Sam_68 said:
Interesting stuff.
I guess I had imagined the panels being shipped pre cut with all the holes cut by laser then the builder would just fold the panels then rivet the lot together, this still leaves you with the problem of folding accurately mayby that could also be pre folded as well. As for the relaxing I take that is why the structures are now bonded? so that the rivets just hold the structure while it is gluing then the bond is in the glue?
While the example you gave of the 79 F1 car is interesting I presume that this means that the lotus was of a simaler level of stifnes to the tubula constructed cars that pre dated it?
A friend of mine is building a small mid engined car with a galvanised steel monocoque. It is laser cut, folded and holes laser cut to a 0.01mm tolerence or something stupid. It is then glued and steel riveted together. All self jigging. It was all CAD designed with a tubular engine frame bolted to the back.
It's super cheap if you were to buy 10 at a time just takes a couple of days to stick together. It's also very light and rigid.
It proves it could be done. He is doing it because he can with no plans to do anything really apart from design and build himself a car.
I would imagine manufacturers stick with what they know and know they can sell. The current market isn't really one that you would want to pitch something new and radical. Or is it?
It's super cheap if you were to buy 10 at a time just takes a couple of days to stick together. It's also very light and rigid.
It proves it could be done. He is doing it because he can with no plans to do anything really apart from design and build himself a car.
I would imagine manufacturers stick with what they know and know they can sell. The current market isn't really one that you would want to pitch something new and radical. Or is it?
Myself and two collegaues freinds are designing a car for Road/RGB championship and Aluminium monocoque is the way were going. Considering that we have all worked in fairly high level motorsport this is not a decision based on hopes and dreams.
Remember F1 went: Steel Space Frame - Aluminium Monocoque - Carbon Fibre Tub.
We can't afford a Carbon Tub so Ally monocoque is the next best thing. As mentioned the peices can be laser cut from a DXF CAD file, its self jigging (if designed right) and doesn't suffer heat distortion like steel. Also the monocoque becomes its own bodywork so no s
tty GRP panels required.
I don't know why somebody is going on about riveting, rivets should only be a supplementary joining method after proper Aluminium bonding. Its not even hard to bond either, Permabond and Loctite sell the stuff off the shelf for a reasonable price.
Remember F1 went: Steel Space Frame - Aluminium Monocoque - Carbon Fibre Tub.
We can't afford a Carbon Tub so Ally monocoque is the next best thing. As mentioned the peices can be laser cut from a DXF CAD file, its self jigging (if designed right) and doesn't suffer heat distortion like steel. Also the monocoque becomes its own bodywork so no s
tty GRP panels required.I don't know why somebody is going on about riveting, rivets should only be a supplementary joining method after proper Aluminium bonding. Its not even hard to bond either, Permabond and Loctite sell the stuff off the shelf for a reasonable price.
I believe its cheaper to produce an Ally Monocoque tub than a space frame dependant on complexity of the spaceframe. But I also think the up front design costs may be a little more than a spaceframe based on discussions I have had with a manufacturer. But I have never been to convinced on that as I have had to get a spaceframe into CAD for laser cutting and it takes a while. It may be the stress analysis aspect that takes more work on Ally.
The Tig welded Ally stuff done by US based kit cars does seem quite stiff but weighs about the same as a spaceframed car when finished.( ie GT40)
Wooden Monocoque thats the answer.........
The Tig welded Ally stuff done by US based kit cars does seem quite stiff but weighs about the same as a spaceframed car when finished.( ie GT40)
Wooden Monocoque thats the answer.........
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