coozer
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 posted on 21/10/08 at 05:54 PM |
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Cycle wing aerodynamics
I'm curious about this aero wing on front cycle wings.
Being a tight git at times, and just having bought a new set after my excursion into the hedge was thinking of modifying them with a little wing on
top with a slit under it to let the air out.
Will this stabalise the wings and go towards preventing the stays breaking? How much will the 'lift' be reduced by?
I understand PPC did a feature on this but having subscribed now for about 2 years I can't remember it.
Any ideas peeps??
Steve
1972 V8 Jago
1980 Z750
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Hugh Paterson
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| posted on 21/10/08 at 06:05 PM |
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Funny u should say that
Looking at aero wings as we speak. I have a couple of mods in mind for the front and rear wings, all input gratefully received, ill try anything
once
Shug
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nitram38
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| posted on 21/10/08 at 06:05 PM |
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Have a look at carbon mods. They do a catering van replica which is aero.
I have a set of 4 for the MotaLeira
[Edited on 21/10/2008 by nitram38]
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smart51
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| posted on 21/10/08 at 06:11 PM |
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It has been discussed on here before. There are several things you can do to reduce lift. One is put holes in the top. The problem is water, mud
and stones may be flicked through. Mesh under the holes may help.
The problem is that cycle wings are vaguely wing shaped and produce lift over the curved upper surface. The lift is produced by the air moving over
the top of the wing, reducing its pressure (bernouli effect?) sucking the wing up. Holes in the wing let the normal pressure air under the wing get
sucked through the holes instead.
Another way of reducing it is to fit a little "spoiler" on the rear of the cycle wing. It reduces the speed of the air flow over the top,
reducing the lift. You could fit a wing on the front to do the same, or you could fit ridges on the front of the cycle wing to divert the air flow
round the sides rather than over the top. Basically, you need to stop the air flowing over a curved upper surface.
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Hugh Paterson
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| posted on 21/10/08 at 06:16 PM |
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The carbon mods stuff is the way to go, wont pay the price though, which is why im looking at it from a fresh angle
Shug
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coozer
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| posted on 21/10/08 at 07:23 PM |
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The carbon mods look the dogs danglys, apart from the price!
Just imagine the wing stays breaking and the font wheel skidding along it like a sledge
Anyway, the little spoiler and slit behind it was exactly what i asked about.
Want to know if a it makes a great difference, is it worth buggering about with me shiny new wings??
1972 V8 Jago
1980 Z750
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Daimo_45
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| posted on 21/10/08 at 07:36 PM |
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Can't remember the exact figure but there was a post on the forum stating the front cycle wings equate to about 10kgs lift or something.
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Rob Palin
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| posted on 21/10/08 at 08:05 PM |
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Unfortunately for the 'sit up and beg' arches it can be as much as about 25-30kg at 100mph and rises rapidly with the square of speed.
The majority of the lift comes from air rushing up the front of the tyre but being slowed down by the tyre rotating towards it and dragging some air
with it (the deeper the tread the stronger the effect, too). It's kind of like a water wheel, lifting the air from behind it and dragging it up
and over the top. The two streams meet at the top and pool up, increasing the pressure there. The wheel arch then just acts as a nice big surface
area for that pressure to act on.
Having arches that extend further around the front of the tyre to stop air getting underneath from the front is the best thing, then louvres in the
top which bleed out that high pressure. Sealing the inner/outer faces of the wheel is *not* a good thing, however, as you bottle the air up more.
Those Catering van ones have the right treatment of the rear (a slight cocavity to increase pressure then a nice sharp edge to separate off) but
don't extend far enough around the front to stop the main problems which happen underneath.
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Hugh Paterson
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| posted on 21/10/08 at 08:56 PM |
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Mmmmmm,more or less what I was thinking Rob, its on my "to do" list increasing the length of my wheel arch moulds for the front arches,
and have some form of aero section at the rear of the arch to improve airflow/release at the back, now wouldnt it be nice to borrow a wind tunnel
Shug
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nitram38
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| posted on 21/10/08 at 09:09 PM |
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Stronger brackets...........................
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Simon
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| posted on 21/10/08 at 11:50 PM |
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As I mentioned in a post of similar vein about 5 years ago, if they are creating lift, surely that reduces unsprung weight?
In a roundabout, kinda way
AB
Simon
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Daimo_45
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| posted on 22/10/08 at 12:46 AM |
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Yer but understeer too
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procomp
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| posted on 22/10/08 at 07:16 AM |
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Hi
I will not tread on Rob's toes with the aero side of it. But the reason most wingstays keep breaking is down to one thing. Poor desighn pure
and simple.
Cheers Matt
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David Jenkins
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| posted on 23/10/08 at 08:41 AM |
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As I said in my recent thread - the wings fall off because of stress fractures caused by the wing stays flexing. If you can stop them flexing then
the problem goes away - anything else (e.g. stiffer stays) is only a work-around.
As for aerodynamics - the wings' effect is minimal compared to the rest of the car!
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Hugh Paterson
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 posted on 23/10/08 at 08:12 PM |
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Ah aerodynamics
I see stuff the aero wings, lets just change the bodywork to "wraparound" pity im not gifted in that department!
Shug
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