Evo 8 WRC Wing

[richard_sykes]

One thing I have noticed about this car is how forward the wing is.
Can anybody explain why they have the wing in such a position?

[Oaksnaf]

Originally Posted by richard_sykes

One thing I have noticed about this car is how forward the wing is.
Can anybody explain why they have the wing in such a position?

Well id have to say an extensive research development program in the wind tunnel, or just one massive face lift.

It is pretty ugly though, but you would rather have winning car than a car with looks.

[richard_sykes]

Looks more like they reversed into the garage with the door not quite up.

Lets just hope its not carried onto a road car.

[Oaksnaf]

Originally Posted by richard_sykes

Looks more like they reversed into the garage with the door not quite up.

Lets just hope its not carried onto a road car.

I doubt this design would make it onto the road, as if they were to do customer feedback forms you would find out that not many people would want to drive such a messed up car, as it does not look beautifully crafted at all.

But it was made in 2003 anyway so it is old news.....

[Lukin]

I remember reading in a tuning style book about the old fashioned cotton test where they tied hundreds cotton strands (loose at one end) to an rear wing-less Escort, drove it at 100 km/h + and observed their behaviour. In turbulent air they move around like crazy (creating drag in the process), but in smoother air they are straight and help the aero effeciency.

By adding a rear wing they were able to remove a lot of the seperation of the air flow that occured as the air passed over the roof and expanded (for want of another word) as it went over the rear windscreen. Basically, before it had no direction and went everywhere, but with the wing it was more streamlined and reduced drag. So much so it added a few extra clicks to the top speed.

I assume it's the same principal for this EVO rear wing, with it being designed to condition the air flowing over the car and off the back window. Comparing the winscreen to the back window, the rear of the car seems to be more discontinuos.

That's my guess anyway, I know bugger all about aero.

[richard_sykes]

Originally Posted by Lukin

I remember reading in a tuning style book about the old fashioned cotton test where they tied hundreds cotton strands (loose at one end) to an rear wing-less Escort, drove it at 100 km/h + and observed their behavior In turbulent air they move around like crazy (creating drag in the process), but in smoother air they are straight and help the aero efficiency.

By adding a rear wing they were able to remove a lot of the separation of the air flow that occurred as the air passed over the roof and expanded (for want of another word) as it went over the rear windscreen. Basically, before it had no direction and went everywhere, but with the wing it was more streamlined and reduced drag. So much so it added a few extra clicks to the top speed.

I assume it's the same principal for this EVO rear wing, with it being designed to condition the air flowing over the car and off the back window. Comparing the windscreen to the back window, the rear of the car seems to be more discontinues.

That's my guess anyway, I know bugger all about aero.

So basically it’s the venturi effect working against you, so they move the spoiler forward to remove the low pressure turbulent air. Sounds pretty

[Lukin]

I guess that's a good way of looking at it.

I think the rear gradient has a lot to do with the drag, hence the move towards aero tube for suspension components over basic circular section. The rear section of the aero tube has a much softer gradient to reduce seperation of the flow and as a result, drag.

[Oaksnaf]

Originally Posted by Lukin

I guess that's a good way of looking at it.

I think the rear gradient has a lot to do with the drag, hence the move towards aero tube for suspension components over basic circular section. The rear section of the aero tube has a much softer gradient to reduce seperation of the flow and as a result, drag.

Also since this car is longer in length than the competition, having the rear wing closer towards the rear windscreen perhaps reduces oversteer??

[richard_sykes]

Would that help under steer much being behine the rear wheel any way?

It would reduce oversteer though (cause from its mass) as its not so far from the front, reducing moment around it?

Sure they have a good reason. Boots a little pain to open now though :lol:

[Lukin]

I'm not 100% sure of the effect on balance. Moving the wing (or any aero device) up and down the length of the car will effect the aero load distribution. The total load on the tyres comes from static weight, weight transfer and aero load, but the aero load varies with speed. As a result, the balance will change between high and low speed corners. It's not always a bad thing (high speed understeer never killed anyone; quiet the opposite in fact) but it's not as simple as saying 'it will reduce oversteer.'

[Oaksnaf]

Originally Posted by Lukin

I'm not 100% sure of the effect on balance. Moving the wing (or any aero device) up and down the length of the car will effect the aero load distribution. The total load on the tyres comes from static weight, weight transfer and aero load, but the aero load varies with speed. As a result, the balance will change between high and low speed corners. It's not always a bad thing (high speed understeer never killed anyone; quiet the opposite in fact) but it's not as simple as saying 'it will reduce oversteer.'

The wing is closer to the rear wheels, so any downforce it creates will have less leverage than if it was farther behind the wheels. This would reduce grip in the back.

Obvioulsy its not as simple as saying 'it will reduce oversteer' i never said that in fact, i said 'perhaps' as i do not know what will and wont happen.

[Lukin]

Sorry, didn't mean it to sound like that.

[Oaksnaf]

Originally Posted by Lukin

Sorry, didn't mean it to sound like that.

Nah its cool

[EVO1X]

I know that they have to remove the rear wing to get into the boot so I cant see the road cars getting it thankfully, maybe they think it makes the evo look less like a taxi

[TRuss]

My guess was that it moved the downforces center of pressure (please excuse me while a make up terminology) closer to the rear wheels. The first rear wings used in F1 were actually mounted on the rear hubs/suspension to put the aero load (I guess...I don't know the proper term) directly to the rear tires. It was banned after some down force induced structural failures. That was around 40 years ago. Aerodynamics have come a long way, so my guess could be way off.

[avsfan733]

it probably is probably aligned with the large low pressure area created by the roofline falling away at the rear glass...this creates a larger space that the given air flowing over the roof (and around the sides but in an attempt to simplify) lowering the pressure because the volume increased for a given mass. tthey probably observed in the windtunnel that the line of that low pressure, the top boundary of it , ran along a line that remained well defined and slightly below the leading edge of the wing causing more efficient downforce by using air that was already slightly lower in pressure anyways.

my two cents

[THR]

loooks like a wind tunnel jobby to me!!
bear in mind that rally cars spend a lot of the time in drift so the air flows over the wrong sides!!

another interesting aero fact... in the lemans cars they used to (not sure if they still do) hang the rear wing way way over the back of the car, not for leverage, but to get better flow from under the car.

[1200Datto27]

Originally Posted by THR

another interesting aero fact... in the lemans cars they used to (not sure if they still do) hang the rear wing way way over the back of the car, not for leverage, but to get better flow from under the car.

They used the wing to create a larger low pressure area behind the exits of the tunnels/diffuser, there by making the floor of the car generate a higher % of the downforce.