I've got a bee in my bonnet about building a contemporary R1 styled 'Messerschmitt' bubble car. Looking at the specs of the original 3 wheeler it's wheel base is just over 2m and weighs in at 230kg. I assume rightly or wrongly that the design of the original would not have had much safety in mind in 1956 and probably made of ali hence the low weight, so my use of steel ERW tube and GRP is more likely to be twice that but with 3-4 times the power using a modern bike lump.
Question is do I keep with the 3 wheel trike theme and cash in on the lower cost of MSVA and road tax
or
give it 4 wheels making the design slightly less of a head ache and hope to get it classed as a heavy weight quad? If quads go through MSVA which is cheaper and less fussy when does a quad become a car? I believe 400kg is the max for a quad and some thing about the amount of power it has comes to mind too, might be some thing I've read in the past?
Any thoughts on weather it's an idea with legs or me just having another brain fart at silly season?

[Edited on 28/12/11 by Talon Motorsport]

weights and bhp etc. for quads here

Looks like you would be restricted to around 50 BHP/TONNE, so it may be best just to bite the bullet and put it through an IVA if you want 4 wheels on your waggon.

I've a mate who took his bike test but only wanted to buy one bike so he brought a 600 and had it restricted to 33hp and rode it for a year on L plates. Past his test got his full uk and had the restrictors removed. If it's possible to do this with all bike engines by a certified garage could the restricters fall off after the MSVA?

to get around the rules so to say , i think you have to 20hp .

either way if you cant build it less than 250kgs for something like a bubble car , id build a proper 4 wheeler and be done with it .

you can build anything you want really , as long as its registered to a disabled person ...........

why not use a really torquey 20hp electric motor and gear it up? will still have only 20hp but have a ton of torque...

You can still use the tricicle regs, which allow higher mass and unlimited engine power than the heavy quadricycles, with twinned rear wheels.
As defined in the MSVA manual:

Twinned wheels
Two wheels mounted on the same axle, the distance between the centres of their
areas of contact with the ground being less than 460mm. Twinned wheels shall be
considered as one wheel.

That is an interesting idea.... question is though if you put the wheels the maximum distance apart would the twin wheels need a diff if it was the driven axle? Would the difference in the turning radious be small enough not to scrub the tyres out to much if it was locked?
I've all so been looking at seating arrangements for two 'normal' sized people. I've seen an audi concept that puts the driver off centre to the right and the passenger sitting behind off centre to the left making a shorter cock pit but more leg room. How much difference would this make in some thing light if there was only the driver? Another way of doing it would be have the driver lower in a 7 type postion and put the passenger slighty higher so they can look over the drivers head but so it draws their feet back. A bit like sitting one a chair rather than formula ford style?


[Edited on 29/12/11 by Talon Motorsport]

Have you seen the new trike from John Barlow of Imperial/Veranti?
There's a basic write up in TotalkitCar and CKC.
I think it qualifes for MSVA but it's not a traditional Isetta-type car.

Razor Cars Link

that looks like an excellent kit ..... pretty much how id like to one , a bit more enclosed tho for the very last penny pinching fuel saving . i wonder why they opted for stainless ? could have just been complete grp .....

in fact ive been looking at boat hulls as a base for the chassis......

I've been giving some more thought to the four wheeled bubble car idea and come to think that a smart car would make an ideal one car donor if offered as a kit. Although the power figures maybe a little under powdered compared to bike engines it has been pointed out that speed is not every thing to every body espesh in some thing light weight. So for now I'm looking at the basic design of the four wheel Messerschmitt GT500 and how it would fair with the IVA regs. Does this appeal to any body or have I lost the plot?

i like the rear and the sides. the front though looks like a face of a mouse.

http://www.designatwizy.co.uk/

the twitzy looks like a similar concept, i kinda have a soft spot for it apart from the front end...

also how easy would it be to get in and out of the car you drew, the side skirts look a little fat to step over. i like them though as it makes the car look wider and more stable but how about have it start narrow at the front and flare outwards as they get further away. it should keep a similar stance but mean you can stand closer to where you need to get in.

maybe look at the zonda and porsche carrera GT as they both have cockpits far forward with less of a bonnet, similar to your design.

if you could get it to sub £3k for a basic little car i think your onto a winner, but it has to look right...

please keep at it as i wouldnt mind one myself, would be a perfect car for students/ beginners

Hi,

I like the idea - there's a bubble car near me that gets wheeled out in decent weather and it has a high WAF (Wife Acceptability Factor) due to its cuteness - far more than a Seven.

How would you deal with the glasshouse? The game model has a very narrow cockpit against the rest of the car - I would imagine this would have to be quite a bit bigger overall.

Are Smart donors common or cheap? I've heard that they are expensive/difficult to to repair so is it easy to find them written off but with minor damage?

Peel microcars are back in production

Facinating project but needs defining to stay on track IMHO.

The rational for trikes is low weight through simplicity by elimination.

So every part has to serve more than one function in true chapman style!

I guess that means monoque construction with the engine as a stressed member, structural seats, bonded in windscreen, combined heating/cooling, and other stuff too clever for me to think of!!

Also as the project gets lighter so trad car parts are increasingly over engineered and too heavy. With lighter bodies the wheel and suspension weight becomes critical - heavy wheels and a light body means that over bumps the body moves and the wheels stay still rather than the other way round.

So ford uprights are out and fabricated ones are in, ditto cast iron hubs replaced with ally and cast wheels with three piece ones. Brakes will probably be bike versions as will springs and dampers. Even tyre weight will be critical racing tyres are half the weight of road tyres but not all are road legal.

Even the electrics will come ne'er scrutiny I bought all mine in one place and could hardly lift the bag! Some original thinking required to keep the design criteria from slipping here.

What compromises are acceptable? Trad locost front suspension is heavy. The Peel uses swing arm which possibly compensates for lack of grip at the rear where there is only one wheel and all the weight. Is this acceptable or will our preconceived notions stand in the way?

Big project to do justice to.

Surely if the peel can get down to 50kg 200kg should be possible for a bike engined version? The bit I can't visualise is the canopy mechanism - doors are notoriously difficult for locost builders.

Neat design by the way

Cheers!

Chat with Smart51 perhaps

In a new twist to this project during today's coffee break chats we came to a few conclusions about what we want from this project and what other people would want from it and they run along the lines of:
when BMW done the new Mini and VW did the Beetle they used styling cues from the original but kept them contemporary so that they are in keeping with current style trends ie bigger wheels, simple lines and chunky interiors . With this in mind we have decided that the purist approach of trying to keep every thing light weight and slim is not going to work with what people would want. So instead of making this project small, light weight and confined we are going for some thing that will be as mentioned in another post 'high in WAF factor' and can be driven by either short and round or tall and narrow drivers and passengers. In short the micro car idea has been binned but we are left with a two seat retro styled bubble car that is contemporary in design but still a plausible 'weekend toy'.