Making a more efficient, aerodynamic soapbox gravity race car

[BamZipPow]

Are there any rules or regulations on the specifications of the vehicles? The lower angle you can sit at will provide less frontal area but it may be a compromise to steering and handling. Look at how the F-16 pilot is positioned in the cockpit. I think the seat is set around 30°. Kinda like recumbent bicycles.

[orengomotors]

Originally Posted by BamZipPow

Are there any rules or regulations on the specifications of the vehicles? The lower angle you can sit at will provide less frontal area but it may be a compromise to steering and handling. Look at how the F-16 pilot is positioned in the cockpit. I think the seat is set around 30°. Kinda like recumbent bicycles.

hi BamZipPow,
Yes there are, want to see them? any section in particular? just tell me and i will transate the rulebook section and post it here.
i will copy the design of the recumbent bike, so i will improve the frontal area,drag and lower the center of gravity!
thankyou

[darcane]

Originally Posted by orengomotors

I can change the seat to be more horitzontal, and so minimize the frontal area and drag. what you think?

I believe that is exactly what you need to do. Streamlining behind the driver will have a significant impact on drag. The lower the driver is, the easier it will be.

Are there any rules that you are required to follow that will affect what you can do with the body?

[orengomotors]

Originally Posted by darcane

I believe that is exactly what you need to do. Streamlining behind the driver will have a significant impact on drag. The lower the driver is, the easier it will be.

Are there any rules that you are required to follow that will affect what you can do with the body?

well, the overall dimensions:




they aren't rules about body position.

[freebeard]

There is a line from the top of the roll bar to the top of 'reinforcing brace to the foot'. Is that defined? Do the top contenders have open or closed wheels? Your drawing with the red fenders could be pontoon fenders, halfway in between. If the front suspension is exposed, all the members could be airfoil sectioned. With rocker A-arms the coilovers could be inside the body.

What about weight distribution (50/50 or biased to the rear)? Rear brakes only? Up on jacks how long will the wheels spin? Does high or low rotating mass have the advantage?

There's a minimum wheelbase but no maximum. A longer wheelbase would allow a recumbent position and better fineness ratio.

[orengomotors]

Originally Posted by freebeard

There is a line from the top of the roll bar to the top of 'reinforcing brace to the foot'. Is that defined? Do the top contenders have open or closed wheels? Your drawing with the red fenders could be pontoon fenders, halfway in between. If the front suspension is exposed, all the members could be airfoil sectioned. With rocker A-arms the coilovers could be inside the body.

What about weight distribution (50/50 or biased to the rear)? Rear brakes only? Up on jacks how long will the wheels spin? Does high or low rotating mass have the advantage?

There's a minimum wheelbase but no maximum. A longer wheelbase would allow a recumbent position and better fineness ratio.

Hi Freebeard,

this line is not defined, is only to explain the "safe area" created by the rollbar in case of rollover.
The top contenders are the sejkora soapboxes and they are open wheeled:

but this year they implemented a kind of front "wing" whit a curved endplates to reduce wheel drag:


the rear suspension is already a pushrod system, now i have to upgrade the front.
i use a tail heavy car, because it has more potential energy.
the wheel now spins for 5 min.
Low rotating mass is better, lower inertia = better acceleration=better braking.
Thank you

[Xist]

That would be interesting. "Hey, why is that kid lying down? Hey! He is winning!"

[freebeard]

Thanks. It looks like they use the minimum width for the roll bar, that will reduce it's drag. Could it pass tech inspection if you zip-tie an airfoil to the back of the roll bar?



This is the best open front wheel I've seen. It has a narrow tire on a wide rim and a smooth cap that overhangs the rim so there is one continuous curve from the leading to the trailing edge. The inner face is also smoothed.

I see what they're doing with the endplate/cycle fender, mimicing F1 race cars. I think the rear part is more important. With a tall, narrow wheel a fender, instead of the 30s swoop your red fender shows would look more like this:



Then, just because I can, here's a picture of an electric racer from the UK.



Do this with a roll bar—Short nose and tall tires. Raise the pedals and move them forward so the seat can move forward. How much contact patch do you need for the corners?

[orengomotors]

freebeard,

what do you mean by "zip-tie an airfoil to the back of the roll bar"?
the smooth wheel caps, it's a fast easy mod that i can do.
My tires have very good grip, so i reduce the contact patch to reduce rolling resistance, i run 5kg of pressure in the tires and they have a very good grip and very low friction with the road.

[freebeard]

Just a wedge-shaped trailing edge that would give an airfoil cross-section. I said zip-tied because safety officials might want it removable for inspection.