underbody rear diffusers

[bige321786]

I see many top end sportscars and racing vehicles designed with these underbody rear diffusers. What are they exactly used for? Do they create downforce somehow, spacing out the airflow under the vehicle? Was studying Colin McRae's Prodrive Ferrari 550 and thought i'd ask. I couldn't get the picture of the 550 because it was too large but here are examples from the 575, Enzo, and the new Maserati.

[drakkie]

they generate a lotof downforce somehow

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flying without wings

[Matra et Alpine]

they generate a lotof downforce somehow

As the air flows under the car it reaches the shaped undertray and now expands into the space available determined by the upward hape of the undertray. This reduces the air pressure in that region. This produces a force pulling the car down to the road.

[bige321786]

thanks Matra

[cp01ae]

As the air flows under the car it reaches the shaped undertray and now expands into the space available determined by the upward hape of the undertray. This reduces the air pressure in that region. This produces a force pulling the car down to the road.

Thats basically what i was gonna say. And to add onto that, the vertical strakes that you see help to keep the car going in a straight line.

[Coventrysucks]

Rear diffusers are used on a few road cars aswell; TVRs, Ferrari, lotus Elise

However they don't always work that well.
With the Ferrari 360 for example, a lot of downforce is created by the diffuser tunnels, but if you go into a tightening corner, the air begins to travel at an angle to the tunnels, and can cause a sudden loss of downforce, which can result in sudden oversteer.
This was also a major problem with the F50 aswell.

[Ferrari Tifosi]

Read: Bernoulli's law, has a lot to do with how the rear diffusers work, as well as air foils, and airplane wings.

[DasModell]

for more info . check www.mulsannescorner.com . where Mike Fuller explains it more technical

[Matra et Alpine]

for more info . check www.mulsannescorner.com . where Mike Fuller explains it more technical

That's a great site, thanks for the pointer DasModell