The roof of the racer

[Flying Dutchman Niels]

Hello all,

Us being Dutch have an endless discussion about the roof that is allowed on the racer. It has probably something to do with the translation.

We found the following:

A steel roll cage complying with the MSA Blue Book shall be installed. A rigid roof of sheet metal (minimum l.5mm steel or 3mm aluminium) shall be fitted to the roll cage. The roof must cover the whole perimeter defined by the four main tubes at roof level. It may be fitted either by being carefully welded to the main tubes, or by being bolted to substantial brackets welded to the main roll cage tubes.

Does this mean that only the rolcage needs to be covered by a sheet of metal (1.5 steel or 3 alu) or does it mean the whole roof of the 2cv ??
If it is only the cage what specs are there for the actual roof.

Can anybody help us out ???

Thanks in advance !!

[pat collier]

hi the regs if I remember are as you described for the roll cage..... This was put in as some were only using thin sheet ali as a roll cage top, so the regs were tightened to ensure that no weight could be saved here.

there is another part of the regs which refers to the roof stating that it has to be completly covered in a sheet of ali, I do remember that when we raced at mondello it was common for some cars to run with the canvas "sunroof" blowing in the breeze... but alas no more..

hope this helps but I its been a while since I looked .....

[Paul Robertson]

The top of the roll cage should be fitted with a 3mm steel or 5mm alu sheet .The canvas roof must be removed and replaced by a metal roof.
HTH
Paul

[Martin Harrold]

Paul - talking of roofs, I'm not the only fellow racer who's curious about the black roof finish on at least one of your cars. Is it from an accident in a paint factory, a roll of old roofing felt which fell of the back of a lorry, or is it some kind of clever, aerodynamically efficient textured surface? My son, who claims to know about these things, thinks the latter. Apparently it's all about holding the flowing air onto the surface of the roof for as long as possible before it peels away as the roofline gets steeper. But he must be wrong, surely?

[Paul Robertson]

He's correct martin.

[Simon Crook]

A lot if not all of NASCAR's run with the mat finish roofs!

[Martin Harrold]

Can we assume that 'matt finish roofs' are fully approved by the Club technical committee and the scrutineer. I'd like to know before I start checking the stock at Carpetright.

[Paul Robertson]

It was very difficult to stick on and made no noticeable difference martin.The only thing it was good for was recognising the car as no one else has a matt roof.

[pat collier]

When I was looking at the re-roofing of our car I looked at the matt finish and ran some tests in a flow chamber..... I could bore you however the effect of drag/downforce co-efficient only cam into play marginally in the draft at snett... otherwise it was actually a negative as appossed to slippery...

There was a legitimate gain to be had on the roofline which is only seen on our old car... this actually adds approc 1.6 mph in the draft and has a slight negative effect on the following car...

Boring yes I can be

[TerryCollier]

Hi

Nothing to do with the roof but on the same subject of flow. Many people polish their heads(not only me being folloically challenged) -- cylinder type. However, you will get increased air flow if you roughen the surface slightly. Ideally you could do with a hatch marking but a very gentle wire wool rub works well. Simply put a smooth surface causes air to cling to it and causes a drag effect. On brake disks this retains heat and is why you will see holes in performance ones. By unsmoothing the surface you will gain an increase in air flow plus an increase in turbulence. Two advantages follow. You are more likely to fill the cylinder and also create more swirl enabling more efficient combustion.

Just a thought

Terry Collier