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Old 05-27-2021, 07:14 PM   #11 (permalink)
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That was design to specific racing class rules. That's why it has four wheels.

One Ecomodder member did a CFD analysis (FWIW) of a feature that would fit it. A bellmouth diffuser.



I haven't found the thread so I can't pass along his results, but it was similar to this one: a gravity racer in Barcelona. ecomodder.com/forum/showthread.php/making-more-efficient-aerodynamic-soapbox-gravity-race-car-32441.html
or this one:
ecomodder.com/forum/showthread.php/aero-teardrop-its-side-28652.html
This one is notable for Permalink #31
https://ecomodder.com/forum/showthread.php/gravity-racer-gallery-extreme-aerodynamics-1208.html
I'me seriously going to find a thread to repost the graphics from Permalink #31 (dates to 2008).

I think it's in the near future also. Mainly because CFD will be implemented with OpenVDB. It's already being rolled into Blender with its physics engine. Coding it is above my pay grade unfortunately. I used to work with programmers. I stand in awe.

Especially Ian Hubert and Dynamo Dream.

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Old 05-27-2021, 07:37 PM   #12 (permalink)
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Speaking of rules, you could plaster the whole vehicle in PV cells and at least one side of the car will be getting optimal sunlight on them. But I do believe that these races also limit the number of solar cells that can be placed on the vehicle.
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Old 05-27-2021, 08:39 PM   #13 (permalink)
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The car body could be a vacuum tube solar collector with a Stirling Engine. Now that's ecomoddin'.
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Old 05-28-2021, 04:34 AM   #14 (permalink)
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Quote:
Originally Posted by Autobahnschleicher View Post
That's an interesting challenge.
I wonder if we could assemble a team ecomodder
There is quite some room for improvement to be seen on these vehicles and their driving strategies.
Um, that's a bit like saying, "Why don't we develop an F1 team - there is quite some room for improvement to be seen on these vehicles and their driving strategies."

I know it's the web, but don't people even think of looking at what has actually been achieved before putting in their oars?

Dear me...
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Old 05-28-2021, 07:03 AM   #15 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
LOL, I was just going to mention that this is evidence for why cars aren't airplanes.

Don't know why the embedded time skip isn't working, but skip to 11:48

Those ultra-low rolling resistance tyres have very little lateral grip unfortunately, with a forward centre of pressure and large rear lift, in sudden changing crosswinds very high crosswind drag coefficient, 40 knot right wind and then 40 knot left wind. It is out of the hands of the driver.

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The car body could be a vacuum tube solar collector with a Stirling Engine. Now that's ecomoddin'.
Why not a vacuum tube solar collector that powers a steam engine? Wouldn't that be more efficient? Steam is actually a bad choice, refrigerant is the new steam. And the team would be putting all their food in the car to cook it because it gets so hot.
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Old 05-28-2021, 10:11 AM   #16 (permalink)
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team

Quote:
Originally Posted by Autobahnschleicher View Post
That's an interesting challenge.
I wonder if we could assemble a team ecomodder
There is quite some room for improvement to be seen on these vehicles and their driving strategies.
I'm not sure, but I thought it was limited to students only.
And other than crowd-funding $ 1,300,000 for the project, you've got out-of-pocket airfare for all team members, plus the free labor of thirty-six people as well. And multi-core processors and CAD-CAM-CFD software, plus shop facilities are provided free of charge ( if you ignore tuition ).
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Old 05-28-2021, 10:17 AM   #17 (permalink)
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Surely all the solar challenges can't be only students?
You want ultra LRR tyres? Your team needs to be personally sponsored by a tyre company, who then charge you quite a lot for the tyres that only last 200 miles.

Unless ecomodder suddenly gets millions of funding, it isn't happening. Shell ecomarathon is slightly more realistic but still wildly optimistic
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Old 05-28-2021, 10:24 AM   #18 (permalink)
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theory

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Originally Posted by Piotrsko View Post
I would believe their aerodynamic theory is a bit in front of even Aerohead, or Julian. Most schools have compute power that dwarfs anything I see here. They definitely have a better manufacturing support system. But we're experienced. Hmmm.
I'm uncertain about any difference in theory. Having CFD to do the pick and shovel work is certainly an advantage ( that would cost us $ 400,000 ( US ), without data cloud models).
Scale-models are extremely expensive, cost as much as a full-scale vehicle, and can't be used for anything else, especially not for tooling.
California teams were transporting their cars all the way to North Carolina and back for full-scale wind tunnel testing at Aerodyne.
If you ignore $ 26,664 / year, for tuition, books, food, and housing, computer, software, and shop facilities are 'free.'
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Old 05-28-2021, 10:35 AM   #19 (permalink)
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transition drag

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Originally Posted by Autobahnschleicher View Post
We're experience eco-drivers and even making it all the way would place us better than many of them that do not finish.
I've also seen quite a few things there that are inducing way more drag than they need to.
Especialy the hard transitions on the catamaran designs are inducing quite some additional drag.
The University of Michigan, 'NOVUM' solar race car project team used SIEMENS' CAD/CAM/CFD. This CFD incorporates smoothing protocols to reduce interference drag at component intersections ( minimum fillet radii ), so they have this covered.
Teams which have no access to wind tunnel validation would be locked into whatever CFD could do for them. Hopefully, all their CFD software includes the interference drag minimization code.
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Old 05-28-2021, 10:41 AM   #20 (permalink)
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rules

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Originally Posted by Isaac Zachary View Post
Speaking of rules, you could plaster the whole vehicle in PV cells and at least one side of the car will be getting optimal sunlight on them. But I do believe that these races also limit the number of solar cells that can be placed on the vehicle.
The rule book changes every 4-years, so teams would be held to whatever limits/ boundaries, were defined in the applicable rule book specifications.

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