Making a more efficient, aerodynamic soapbox gravity race car - Page 26 - Fuel Economy, Hypermiling, EcoModding News and Forum

Grant-53 · 06-30-2016, 10:15 AM

The discussion on leaf spring suspension at recumbent.com was very intense and some very capable designers were involved. The danger was that the leaf would twist throwing off the geometry. The use of wide springs, L stock stiffeners, and an A arm dealt with that issue. Control rods can be faired with light sheet plastic.

orengomotors · 07-24-2016, 05:12 PM

Well, This year the rules had changed and it's compulsory having a bottom,belly on the car to prevent driver feet or legs to touch the ground.

So, i have to build a " flat bottom" before august 16 to be able to compete.
My question is, it's possible to build a bottom for the car that also improves the aerodynamics?

any tips?

this is going to be like another little subproject, like the nose and the suspension.

thank you!

edit:

i have designed that so far, it's ok? the diffuser has to be 5 degrees for optimum drag?

freebeard · 07-24-2016, 06:23 PM

???? I can't follow the comparisons of length and angle. It's always a flat plate. I think it should be an exponential curve. Or a raked flat body.

It would be interesting to see the wheels and body on top. The intersection on the side could be a square edge, a radius or a horizontal 'running board' fin. What do you plan?

orengomotors · 07-25-2016, 04:29 AM

orengomotors · 07-25-2016, 04:30 AM

Quote:

Originally Posted by freebeard

The intersection on the side could be a square edge, a radius or a horizontal 'running board' fin. What do you plan?

what do you mean?

freebeard · 07-25-2016, 01:37 PM

This, the third choice:

The difusser has evolved nicely. At this point, should I assume a front diverter with upside-down wheel spats is in the works?

aerohead · 07-25-2016, 05:37 PM

Quote:

Originally Posted by orengomotors

Well, This year the rules had changed and it's compulsory having a bottom,belly on the car to prevent driver feet or legs to touch the ground.

So, i have to build a " flat bottom" before august 16 to be able to compete.
My question is, it's possible to build a bottom for the car that also improves the aerodynamics?

any tips?

this is going to be like another little subproject, like the nose and the suspension.

thank you!

edit:

i have designed that so far, it's ok? the diffuser has to be 5 degrees for optimum drag?

*McLAREN claims an advantage with having the entire belly inclined (raked),with ground clearance increasing slightly as it proceeds aft.They offer no specifics.
*Otherwise,for a diffuser,starting where your illustration shows,the lowest drag is at 4-degrees upslope.

freebeard · 07-25-2016, 09:08 PM

That's the diagram I don't get.

I presume l(c) is overall length? What is the relationship between the angle and height graphs? The two curves don't track each other.

Maybe if there was a curve for l(d)/l(c)=1 I could get the sense of it.

orengomotors · 07-27-2016, 04:49 AM

Quote:

Originally Posted by freebeard

At this point, should I assume a front diverter with upside-down wheel spats is in the works?

I think that a front splitter could be dangerous and that the diverters would have little effect, what do you think?

orengomotors · 07-27-2016, 04:51 AM

Quote:

Originally Posted by freebeard

That's the diagram I don't get.

I presume l(c) is overall length? What is the relationship between the angle and height graphs? The two curves don't track each other.

Maybe if there was a curve for l(d)/l(c)=1 I could get the sense of it.

i don't get it too