Li-on Wave II X-Prize entry

[aerohead]

Originally Posted by NeilBlanchard

My question about the Wave II is whether the underside is too steep? The top seems to be flatter than it needs to be.

From Hucho,any diffuser drag reduction is lost once the up-sweep angle exceeds 11-degrees.
Shooting from the hip,if we give the Wave conventional mirrors,the Cd degrades to 0.166.
If we give it a generic cooling system also,we're looking at maybe Cd 0.184.It looks like AeroCivic out-performs the Wave II.
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The Bochum University Solar GT also has a 'fast' diffuser,but is a longer car and is rated at Cd 0.134.

The Cambridge University Eco Racer has a very conservative diffuser,is a longer car,and is reported at Cd 0.10.

There's no way to quantify what actually sets the cars apart,aerodynamically.My opinion would be to follow the 2.5-4 degree rule.
The air under Spirit of Ecomodder's diffuser is 'nervous'.In September I will have a 2.5-degree extension to try.

[NeilBlanchard]

I'd say the Wave II underside is much steeper than 11 degrees? It is much higher up than the (Bochum University?) solar racer.

[aerohead]

Originally Posted by gafhj

Why did they cut the rear wheel fairings well ahead of the back of the car? Looks like a lost opportunity to boat tail them.

It's a really good question,and I have no earthly idea why they did it.I would like to me those folks one day and talk about it.

[aerohead]

The Wave does seem higher.The wheel enclosures are thicker,and tires much wider.That could explain a lot about the differences in Cd right there.
The angle of both cars suggest induced drag.This showed up on my CRX at Bonneville and I had to duct tape and cardboard this area closed to pickup speed (mpg afterwards).
Perhaps the fore/aft weight distribution created a light rear end,and for aquaplaning stability,they designed in down force back there to help mitigate that.
Also,the wake drag behind the wheels would provide high speed stability,which even Jaray realized the importance of in the 1920s.
These X Prize cars were intended for mass production,so they'd have to anticipate all conceivable driving situations with certified idiots behind the wheel.
Just guessin'.