Mercedes-Benz Bionic (boxfish)

[NeilBlanchard]

Phil -- I just Googled "Honda Dream-2 solar racer" and got motorcycles and ... the usual Internet noise... Any images you can point to?

[NeilBlanchard]

Thanks Phil. The consensus of a best case Cd of 0.1 for a 4 wheeled road going car seems to be gathering...

[NachtRitter]

Try:

"honda dream" -motorcycle +solar 1996

as a search term... provides some reasonably good results... though still not much.

[RobertSmalls]

The Dream II, at 6m long, 2m wide, 1.1m tall at the center, and 170kg:


There are a very small number of solar cars with lower Cd, and you could picture increasing their wheel count to 4 without too much drag, but I'll agree that we have yet to see >0.10 for a "car". For a "reasonably practical car", I still haven't seen anything less draggy than the Probe V.

[NeilBlanchard]

I think Dave Cloud's Dolphin has a good chance of beating the Probe -- though it might need front wheel skirts? The overall shape beats the Prove V, hands down -- the Dolphin comes to a point at the back, fer cryin' out loud!

[Madact]

Interesting developments:
Mercedes-Benz Bionic car: Boxfish stability and agility paradox finally solved.
Boxfish swimming paradox resolved: forces by the flow of water around the body promote manoeuvrability | Journal of The Royal Society Interface

So, the question become, how much of Mercedes' quoted fuel efficiency comes from the aggressive taper, kammback, clean lines, wheel skirts and drivetrain design of the car - and how much from the 'biomimetic' aspects of the design?

[NeilBlanchard]

Thanks for bumping this thread - I don't think it matters about the bionic aspect; if it works, it works.

[Madact]

Originally Posted by NeilBlanchard

Thanks for bumping this thread - I don't think it matters about the bionic aspect; if it works, it works.

True - the overall package of the MB Bionic concept is no doubt better than most current production cars. But if the boxfish 'box' isn't a great starting point for aero drag and stability, that's significant info. The paper is also comparing to other fish so the question of whether a it's better or worse starting point than a traditional 3-box, fastback or squareback design isn't addressed by the reference AFAICT.

On a side note, how's the CarBEN going? (Not that I'm razzing you - I've had a HPV trike shell mold 'in progress'/stalled for about 3 years now, so I can't talk ). Did you ever do any CFD on that? Being built from Sketchup models, if I understand correctly, would the Sketchup model be accurate enough to do CFD from?

[NeilBlanchard]

I am now working full time, and CarBEN is still moving, but I have to build an addition on my garage to continue. SketchUp models are holey and mine is no exception. We have tried CFD on it, and it is not accurate.

[aerohead]

Originally Posted by NeilBlanchard

Phil -- I just Googled "Honda Dream-2 solar racer" and got motorcycles and ... the usual Internet noise... Any images you can point to?