akshay67

If any!

OK, spare me any lectures on Berneulli (sp?) because I spent 3 yrs as a physicist.

I want objective results. Specifically, I would like to know about the Sti 5, 6 and 22B/WRC spoilers as seen on the DR motorsport page.

Cheers guys.

DaveW

Not sure about the other types but this one really works



After I fitted it I drove over a crisp packet and it shot 15 ft in the air

DaveW.

Hoppy

Good question, and I'd like to know what's actually going on back there.

But, as I understand it, the rear wing is actually just a 'spoiler' in that it does not produce positive downforce, but interferes with the airflow so as to prevent lift.

Does it produce downforce, and if so how much and at what speeds?

Richard.

Greenfin

This aerotesting shows what is going on......

http://www.autospeed.com/A_1055/page1.html

/Greenfin

Scooby Dooby Blue

The UK300 spoiler produces 25% extra downforce at 100mph.
This spoiler is pretty tame compared to the likes of the above (OMG...what an eyesore) , so draw you own conclusions.
Paul

Mcbrun555

Sorry to correct u buddy but the UK300 produces NO downforce
they REDUCE the lift generated by the airplane wing shape of a car by 25%.

Not many road cars produce downforce, but i believe a lotus exgige generates downforce by the shape of the underside of the car.

Mcbrun555

nigelward

...and it is recommended that the front splitter (UK300) is also fitted at the same time to reduce lift at the front of the car to maintain the cars balance.

Edited to be a little more specific.

[Edited by nigelward - 3/30/2002 5:30:23 PM]

Pete N

Just to provide a little input on the reply above "the UK300 produces NO downforce; they REDUCE the lift generated by the airplane wing shape of a car by 25%."
This is correct but the _wings_ themselves DO produce downforce, though not as much as the lift produced by the car itself as it moves through the air - therefore the net aerodynamic force on the car is still a lift force. HTH!

teknopete

Dave,

U bin had m8 thats no a wing thats a picnic table

IMHO none of them do much until u r above 70 mph (unless they weigh 2 much), the sti wing fitted on mine definately changes the air flow though. I remember after fitting it going out 4 a run and @ round 40 - 50 mph there was a definate air sound from the back.

Pete

cheeseboy

saw this the other day, was quite interesting... will try and find the doc to go with it...

ScoobyMann

I think you need to differentiate between a "spoiler" and a "wing" (actually an "aerofoil")

A spoiler alters the shape of the rear of the car to interrupt airflow by moving the separation point of the airflow to a point where turbulence is produced (turbulent airflow creates less lift).
This lessens the effect of Benoullis principle and stops the car behaving like a plane wing and lifting.

A "wing" is a true aerofoil (like the 22Bs as I understand it) which will actually create downforce (or lift if you turn it upside down). The amount of downforce produced will be determined by the amount of airflow over the car and the angle of the wing relative to the airflow.

Hope this helps (and that its correct !)

ScoobyMann

spence7

I'm thinking of buying a Dyson and fitting to the underside of my car ha ha ha

slippyr4

You could just put lots of bricks in the boot.

Or, nick a wing off a 747 (they probably wouldn't notice), invert it, and stick it on the boot lid.

spence7

yeah or a network of tunnels on the road which via cable and rollers pull the car hard down onto the tarmac

spence7

sorry network of tunnels UNDER the road

Floyd

iTrader: (9)

On the MY01's accessory list, they offer rear undertrays that go under the bumpers. I don't know if they are just cosmetic/asthetic or not or whether they actually do something.

The rear bumper acts as an air dam under the car where the spare wheel well is. It would baloon out at speed if it wasn't rigid and this can't be good for drag or downforce. I think that's why a lot of the red tags are pointing up on the rear boot lid around the number plate. It would be nice to see the same experiment with an undertray fitted.

F

EvoRSX

Just to follow on from ScoobyMann's reply, the other thing to note is that for a wing/aerofoil to be effective, it has to be in non-turbulent air therefore you have to mount the wing high enough above the rear end of the car so that the airflow over it isn't affected by the turbulent air produced at the rear of the car.

Of course, with an Evo wing, I don't have this problem The only problem I have is rearward visibility

Andy

akshay67

From the diagram above it would appear that airflow seems to be reasonably smooth off the roof and on to the wing, therefore allowing lower pressure under the lip of the wing (faster airflow) and higher pressure on top (slower airflow) if the lip is angled as in the STi 6 spoiler -> downforce at higher speeds. I'm still not sure whether this happens in practice - I guess sensors in the rear suspension would reveal all.

Also, does the EVO wing actually produce downforce?