gregf27
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| posted on 6/9/08 at 04:21 PM |
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Cycle wings with vents on?
I remember seeing a few of these about last year, they had air vents in them and were supposed in increase down force??
Any one know if you can still get hold of them and from where??
any one got them fitted to their 7 -any benefit to the standard ones??
cheers
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rusty nuts
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| posted on 6/9/08 at 04:33 PM |
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Carbonmods do some with an aero section which is supposed to reduce lift . Expensive but you get what you pay for
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gavin174
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| posted on 6/9/08 at 06:27 PM |
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got these off ebay about 18 months ago
about £100 the pair
never drove car with other type of wing
so dont know if its made any difference (600 x 450).jpg)
http://www.essexkitcarclub.com
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TOO BADD
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| posted on 6/9/08 at 07:25 PM |
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Can't see they would make any noticable difference. Have decided to get the cardboard, pencil and ali out to make my own front downforce this
winter as I feel a bit disconnected with the steering at 110 plus. Tracks of course !
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scutter
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| posted on 6/9/08 at 08:26 PM |
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The vents in the wings will transfer high pressure underneath to the upper surface thus reducing lift and to some extent drag.
The thing to remember is that the water you've just driven through won't be channelled around the arch, it will fly at vehicle speed
straight out of the arches. The next thing in line is your face/right elbow
ATB Dan.
[Edited on 6/9/08 by scutter]
The less I worked, the more i liked it.
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Chippy
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| posted on 6/9/08 at 10:18 PM |
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Having suffered from lift at very ilegal speeds, (private roads of course), my cure can be seen on my Avatar, and works very very well. Cheers Ray
<<<
<<<
<<<
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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smart51
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| posted on 8/9/08 at 01:32 PM |
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The cycle wings on a seven create a lot of lift, even at road speeds. The lift is due to air flowing over them at high speeds, reducing the pressure
over the wings and "sucking" them up.
Holes, vents and louvres will allow higher pressure air from under the arches through, reducing the lift.
Water, mud and stones flick off the wheels at any speed. These are normally caught by the cycle wings. Put holes in the wings and they'll fly
though hitting you in the face. Long louvres sloping down to the front may reduce this. Grille may reduce it further. These will get clogged up
with mud on wet days.
The little wing section on the rear of some caterhams and others reduces drag more than lift. They make the air separate more cleanly and are angled
to reduce the size of the wake.
If you really wanted to go for it, you should make the front face more rounded (viewed from above) rather than flat. You should cover over as much of
the wheel as you can on both sides and you should extend the rear so that the sides taper in at 22°, as viewed from above. You'll have an odd
lookin pod over your wheels though.
[Edited on 8-9-2008 by smart51]
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Triggerhappy
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| posted on 8/9/08 at 06:21 PM |
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Smart51...could you make an illustration?
Im just an stupid swede trying to understand the english technology terms...
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Rob Palin
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| posted on 8/9/08 at 06:46 PM |
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That's excellent advice but there are a few bits i don't understand.
quote:
Originally posted by smart51
Holes, vents and louvres will allow lower pressure air from under the arches through, reducing the lift.
You mean higher pressure under the arches, don't you? Air rushing up the front of the tyre meets that dragged back around by the rotation of
the tyre causing a mini-stagnation at the top.
quote:
Originally posted by smart51
If you really wanted to go for it, you should make the front face more rounded (viewed from above) rather than flat. You should cover over as much of
the wheel as you can on both sides and you should extend the rear so that the sides taper in at 22°, as viewed from above. You'll have an odd
lookin pod over your wheels though.
Covering over the outside face of the wheel & arch actually makes things worse, as it bottles the air up inside. I've tried & tested it
on a 7 in the wind tunnel - doesn't help.
Tapering & boat-tailing is great, but why 22 degrees specifically? Wouldn't the optimum angle depend on parameters which could vary from
car to car (like tyre size and width)?
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smart51
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| posted on 8/9/08 at 07:36 PM |
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quote:
Originally posted by Rob Palin
Tapering & boat-tailing is great, but why 22 degrees specifically? Wouldn't the optimum angle depend on parameters which could vary from
car to car (like tyre size and width)?
From text books I've read, various studies have shown that 22° is generally the best for low drag. Lower angles fair better in side winds in
the real world but steeper angles cause the air flow to separate causing turbulence and drag.
For very large shapes, a curved taper is best, with 22° in the middle or a little after and perhaps a bit more at the point.
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smart51
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| posted on 8/9/08 at 08:05 PM |
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quote:
Originally posted by Triggerhappy
Smart51...could you make an illustration?
Im just an stupid swede trying to understand the english technology terms...
Thinking about it, 14° was the optimum angle for a slope at the rear. for very long slopes, the curve should reach 16° or more by the end. There is
a formula for the optimum curve but I never bothered to learn it.
 
Rescued attachment wing.JPG
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Triggerhappy
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| posted on 8/9/08 at 08:28 PM |
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Many thanks for illustration.
It seems to me that reducing drag is requiering some unpractical aerodynamic modifications out of my reach.
Moulding cyclewings in that shape will detoriate overall look“s and problably make possible steering angels unpractical.
If concentrated on just reducing lift (or actually generating downforce )what would the most "bang for the buck" design be ?
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scutter
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| posted on 9/9/08 at 08:45 AM |
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I think anything above 14 deg angle of attack is when an aerofoil stalls.
As for the CSR wings, they appear to be the best soloution.
ATB Dan.
The less I worked, the more i liked it.
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Rob Palin
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| posted on 9/9/08 at 12:05 PM |
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It's very difficult to define meaningful rules of thumb with aerodynamics and any quoted figures like these really should have a long list of
caveats with them.
For example, different aerofoils will stall at different angles, from just a few degrees up to 30 degrees and beyond, depending on a range of
different influences.
I've designed quite a few different bits of bodywork like this over the years (including the original CSR wheelarches for C******m) and never
found a general solution that works in a majority of cases. While that's a pain from a practical point of view, I can't complain as it
keeps me in employment! 
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