BenB
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| posted on 13/11/06 at 12:49 PM |
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Windstop
Does anyone know of a 7 running with a windstop? Most of the new convertibles seem to be fitted with them to help with turbulent flow into the
cockpit... A fair few of the Cat clones seem to suffer with negative cockpit pressure (causing tricky breathing) at speed- don't know about
physics of turbulent flow in a Locost but wondered if putting a mesh in front of the rollbar would help correct this?!?!?
What does anyone reckon? Might do it to see what happens...
Need to get on the road first and get the tracking sorted. Going > 50mph was a little bit hairy on the way to SVA due to the tracking being all
over the shop... Didn't help that it was Pi$$ing it down in traditional SVA stylee and my baseball cap did it's ejector seat impression @
45mph!! Actually, negative pressure wasn't a problem cause I hadn't fitted the windscreen @ SVA- it was more like forced induction
breathing!! But the screen's going on tommorow......
Ben
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http://www.ipetitions.com/petition/kitcarreg/
Petition for the Rationalisation of kit car registration
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StevieB
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| posted on 13/11/06 at 12:52 PM |
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Can't hurt to give it a try - better way would be to have the mesh as close to the back of the drivers seat as possible though (look at the
likes of merc/porsche/bmw units and see how close they are to the seats and also how high they are.
Or, how about a piece of perspex?
[Edited on 13/11/06 by StevieB]
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Hellfire
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| posted on 13/11/06 at 01:00 PM |
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I know a few people who use them to great effect.
Phil
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3GEComponents
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| posted on 13/11/06 at 01:07 PM |
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I've seen a picture of a 7 with a perspex panel fitted in the roll bar opening, i think it was in an article about MK in Total Kit Car Mag.
Not 100% sure though.
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BenB
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| posted on 13/11/06 at 01:19 PM |
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Sweet- I'll give it a try.
The seat is pretty near the roll bar on my car...  6ft4 in a locost means seat ramned as far back as it will go!!
Then again, better than the Fischer Fury I drove round Ireland in with the Se7ens.net tour7 group...
http://website.lineone.net/~btbromilow/carbeach.htm
Had to rip the seat out and sit on a cushion on the floor. Not so comfy when the car was lowered to the max and crashed heavily when going over
bumps- I didn't need 5th gear to tell me that it's bad for my spine 
Scarily, of the three cars in the photo only the middle one still exists in the same form. The left one (my one) blew its Xflow in spectaular form 50
miles from home and then generally fell apart. My brothers car on the right was thoroughly trashed when he barrel rolled it at Cadwell Park. Slid it
into the tyre wall sideways, car flips up and lands on its top (ain't got to roof 'init!), bodywork (with filler cap) shifts relative to
the chassis (with tank attached) and pulls the hose of the tank. Tip-over valve ain't much good when that happens and you're stuck upside
down (and no chance of getting out until the marshalls arive) with petrol hosing over you and glowing red headers a foot away.....  But alls well
that ends well, only a few broken ribs and a trashed car.... and changes to the rules for the 750MC so filler caps have to be attached to the
chassis!!!
Ben
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Rob Palin
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| posted on 16/11/06 at 08:19 AM |
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This is something i got quite heavily involved in at work a few years back,so i might be able to offer a bit more background info which might be of
interest.
As an open-top car moves through the air, the main windscreen creates a kind of hole in the air behind it and air tries to rush in from the sides and
rear to fill up this 'void'. Depending on the length and shape of the back end of the car, the void region will either close back up or
stay open (almost certainly the case with a 7), but the process is highky unstable and ven if the bubble is closed it will tend to burst after a
maximum of a second. In either case the airflow in that region will still be highly turbulent and generally directed forwards, not in the direction of
vehicle motion.
The screens between the seats in convertibles help to stabilise the bubble region a bit by controlling how much air can flow forward to fill up the
void. A certain amount of flow is necessary but the natural tendency is for more than that, exacerbating the instability. Normally the porous mesh
screens are better, and partly self-regulating, whereas a solid one tends to settle the flow around the lower half of the cabin whilst increasing flow
speeds in the upper parts (faster but more consistent, which is apparently more comfortable).
Fir a 7 i'd suspect that closing the bubble in the neat way those screens are designed to do would be near impossible as there simply
isn't enough car left behind the main windscreen for the aerodynamic mechanisms to sort themselves out. Putting a screen behind you would still
help though, but in a less sophisticated way: simply by physically blocking a lot of airfow that would otherwise have had to come past your head on
it's way into the void.
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