Tappits
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Registered: 25th Mar 05
Location: Rotherham
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Are there any good solutions to get some, i mean any rear end downforce at all?
the spoilers on the back of the new impretza wrc looks nice,
any one got any pics of good spoilers on corsa's? (not like there's loads of R&D goes into corsa dynamics or anything but hay)
i was thinking of putting a fully flat floor from front to back with it coming up at the back in some sort of way to increase it a little but don't really know.
it would help if i new what i was asking as well 
[Edited on 06-03-2009 by Tappits]
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flybikeslee
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Registered: 2nd Jan 07
Location: Liverpool
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wiki bad combt kit
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flybikeslee
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Registered: 2nd Jan 07
Location: Liverpool
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seriously though what issues are you havng with downforce
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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what do you use you car for?
If its not a full on track car you just going to waste time/money doing it.
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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do a google search on aerodynamics..... its not very simple.
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jr
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Registered: 20th May 02
Location: Kent
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 no corsa goes fast enough or needs rear end downforce
and a spoiler will add more drag anyway
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Nic Barnes
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Registered: 5th Apr 04
Location: nowhere near ginger people
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quote:
Originally posted by AK
do a google search on aerodynamics..... its not very simple.
i thought searching for stuff on google was pretty simple.
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Tappits
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Registered: 25th Mar 05
Location: Rotherham
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it is a full on (should be bold) track car (well soon lol)
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flybikeslee
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Registered: 2nd Jan 07
Location: Liverpool
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still, money spent on weight distribution, decent suspension etc will be better
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jr
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Registered: 20th May 02
Location: Kent
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quote:
Originally posted by Tappits
it is a full on (should be bold) track car (well soon lol)
You dont need it, a rear deffuser (sp) would be better, create less drag as well
first build and develop the car, dont worry about problems like rear end downforce, which wont exsist to start with
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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a flat floor and rear defuser will speed up the air and smooth it out under the car = good. But to do it properly you'd need a lot of time and testing.
A practical test to do (if you dont have a wind tunnel) is to take loads of small 2-3" stands of wool all over the car. Take it for a drive and observe it from another car. See where the air is pushing/flowing etc
But there a prob a million more practical things to be done to a corsa before all that crap
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dhdev
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Registered: 22nd Dec 05
Location: Midlands
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The best way to go is flat bottom from front to back as you have suggested. The front should be extended out to form a splitter at the front. On a blunt nosed car like the corsa there will be a large high pressure region at the front, placing a splitter here will provide large amounts of downforce and reduce understeer. The flat bottom is the region that will produce downforce on the underbody, not the diffuser ( a common mistake ) as the air speeds up along the smooth narrow passage under the car it will have to speed up to maintain mass flow, this high speed produces low pressure, which acts on the large region formed underbody. The diffuser at the back returns the airflow back to the higher pressure, slower speed of the surrounding air and reduces drag. Sideskirts will be required to prevent air from migrating (being sucked in) from the sides of the car to the underbody region. The better this is 'sealed' the better, as any air that is drawn in reduces the low pressure on the underbody.
Spoiler wise it is best to go for something that resembles an upturned aeroplane wing, hence the term rear wing rather than spoiler. These produce downforce through pressure differnce across the two surfaces of the wing, whereas a spoiler has a high angle of attack and causes a lot of speed sapping drag.
HTH
[Edited on 06-03-2009 by dhdev]
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Hamish
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Registered: 4th Apr 05
Location: Ashtead, Surrey Drives: 100bhp Mint with Hole
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quote:
Originally posted by jr
no corsa goes fast enough or needs rear end downforce
Timruds 
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jr
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Registered: 20th May 02
Location: Kent
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tim ruds, IMO wouldnt do 178mph
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Hamish
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Registered: 4th Apr 05
Location: Ashtead, Surrey Drives: 100bhp Mint with Hole
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didnt the stack dash proove that?
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jr
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Registered: 20th May 02
Location: Kent
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its only as good as the calibration/sensors
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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Someone with knowledge of vehicle fluid dynamics and aero technology came up with this. Unfortunately an idiot then welded it to the boot of his diesel Corsa.
That'll do the job.
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Gareth F
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Registered: 16th Jan 08
Location: Location Location
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Trolley 
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Ste
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Registered: 5th Mar 03
Location: Taif, Saudi Arabia
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Seriously, if you want a car that goes that fast, don't build a Corsa. If you do want a fast Corsa, spend your money on handling, engine, tyres.
Failing that and you still want to do it, just rivet plastic or carbon fibre sheets under your car. The extra weight you add will undoubtedly offset the performance benefits you will gain.
Also a spoiler doesn't produce downforce, it prevents lift/downforce (depending on what you want to prevent) by disrupting the flow of air over a surface.
Companys will spend millions in wind tunnels developing aerodynamics. It is not something you can do in your shed. One misplaced angle and you could actually make things worse. Dhdevs mentions about the air under the car creating downforce as it has reduced pressure, but if your angle of attack to the road is out and you cause a funnel effect this will in turn produce lift and the car will 'float' on the cushion of air under it, much like a hovercraft. Too much nose down will cause a vortex at the rear as air from behind the car rushes back to fill the area of low pressure. Thus slowing you down.
I am by no means an expert on this subject but my military aerodynamics and stability experience and also the time i have spent with aircraft designers and engineers in the aerospace industry have given me the inclination that this isn't an easy thing to blag.
IMO: Buy a faster car that has had millions in r&d done already. 
I would rather lose by a mile because i built my own car, than win by an inch because someone else built it for me.
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Mike
Organiser: North West and North Wales
Premium Member
Registered: 20th May 06
Location: nr. Skipton, North Yorkshire
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quote:
Originally posted by munk3yrac3r
Off his Trolley
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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quote:
Originally posted by Ste W
but if your angle of attack to the road is out and you cause a funnel effect this will in turn produce lift and the car will 'float' on the cushion of air under it, much like a hovercraft.
Or flat bottom, curved topped car produces Audi TT syndrome
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Ste
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Registered: 5th Mar 03
Location: Taif, Saudi Arabia
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If Audi couldn't get it right then DIYers have no hope really. as long as you don't mid a slower acceleration why not fill the car with paving flags for that extra downforce?
I would rather lose by a mile because i built my own car, than win by an inch because someone else built it for me.
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Novaneil
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Registered: 26th Oct 06
Location: Leamington Spa
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Having read the above, could I have views opinions on this spoiler please...
Lots of Rally Corsa's use it and I was going to get it for mine as I was hoping it would make the backend feel more planted on fast 90/100mph+ corners (Backend has no weight what so ever (Fibreglass tailgate, poly carb windows and stripped)
From what some of you have written above its just going to cause drag???
Its from here:
http://www.eurorallye.co.uk/product_info.php?cPath=8_52&products_id=697
Neil
[Edited on 07-03-2009 by Novaneil]
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l15ter
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Registered: 1st Feb 08
Location: Berkshire
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quote:
Originally posted by jr
no corsa goes fast enough or needs rear end downforce
and a spoiler will add more drag anyway
x2
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dhdev
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Registered: 22nd Dec 05
Location: Midlands
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quote:
Originally posted by Novaneil
Having read the above, could I have views opinions on this spoiler please...
Lots of Rally Corsa's use it and I was going to get it for mine as I was hoping it would make the backend feel more planted on fast 90/100mph+ corners (Backend has no weight what so ever (Fibreglass tailgate, poly carb windows and stripped)
From what some of you have written above its just going to cause drag???
[Edited on 07-03-2009 by Novaneil]
It is going to cause drag Neil, but I wouldn't worry about that with a 2.0 turbo under your bonnet, unless tops speed runs are your thing That's a classic spoiler, it'll interupt the airflow over the car and cause a high pressure region in front of it, which will act downwards on the flat roof ahead of it. In turn you will have a wake behind the spoiler that will pull the car backwards.
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