BOcruiser aerodynamics

[sgtlethargic]

I like the BOcruiser, especially these shots of it. It's a solar car that looks much more like a street car. It has a reported 0.135 drag coefficient (I emailed).

How did they do it?

[sgtlethargic]

What is this rear feature called and how does it work?

[NeilBlanchard]

The part you can't see - the underside - is also done right. It is rising up toward the back.

Edit: the picture of the back shows the rising underside, that contributes to the ultra low drag.

[botsapper]

2009 Hochschule Bochum SolarCar design.

Das SolarCar Team 2015 design. SolarCar Team Bochum – ThyssenKrupp SunRiser

ThyssenKrupp SunRiser – SolarCar Team Bochum

[freebeard]

It may appear to be like a street car, but the rising underside compromises interior volume.

In a way, it's related to the Colani C-Form with it's inverted-wing shaped body, or the new Ford GT or Ferraris with their external duct work. In this case, one side of the duct is the ground.

[Xist]

Does not seem to have plan taper.

[Stubby79]

I like it. And it almost looks big enough to be useful, unlike many of the marathon racers which are ridiculously small and would get run over on the street.

[aerohead]

One thing to keep in mind about the reported drag coefficients,is the velocity and Reynolds number in which they were measured. Driving speed for the Solar GT was around 35-mph,which might have it in a sub-critical Rn to take advantage of laminar boundary layer (cheating if true!)
Both the Cruiser,and it's offspring,the Solar GT both share Luigi Colani's inverted airfoil 'diffuser.'
Here's the Solar GT

Both cars have good sectional density.The roof is a bit fast,but it's a solar car and this might be a concession to solar insolation.

Some comparisons would be the 1981 Buchheim et al 'Flow' body,Cd 0.14

The 1993 GM EV1 LSR record car,Cd 0.14

The 1985 Ford Probe-V concept,Cd 0.134

The 1987 GM Sunraycer,Cd 0.089-0.141

The 1922 Paul Jaray 'pumpkin seed,Cd 0.13

The 1957 MG EX 181 LSR,Cd 0.12

!993 Honda Dream 2,Cd 0.10

2013 Cambridge University CUER,Cd 0.10