Making a more efficient, aerodynamic soapbox gravity race car

[orengomotors]

Originally Posted by botsapper

...use spray foam too.

i used foam

[orengomotors]

Originally Posted by freebeard

Yikes!

yikes = disgust?

[aerohead]

Originally Posted by orengomotors

thank you! i understand it now.

so the nose has to be rounded?
the nissan delta wing nose is poorly designed?

Nissan had plans to run the Delta-Wing at the Indianapolis Motor Speedway.In the past,speeds as high as 235-mph have been attained there in the curves.
If the Delta Wing were going this fast,it would be approaching transonic flow,where the air begins to compress,and supersonic shockwaves can form on the body where extreme accelerations are present.
The boundary layer cannot pass through a shockwave,and this would alter the center-of-pressure on the car,destabilizing it for a high speed crash.
So the nose is more ogival,to deal with shockwave drag,something which actually hurts a low-speed racer.
A 'bulbous' nose is all you need for your velocity.It's not sexy,but the air loves them.Here is Bochum University's solar racer's nose.Very low drag!

[aerohead]

*diffuser angles as steep as 11-degrees will reduce drag.The lowest drag is achieved with 2.8-degrees and a long diffuser.
Second best is a 4-degrees on a 'short' unit.
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*Those two canopies should work well for you.
If the roll bar must be so tall,let the tubes penetrate the canopy top to allow proper streamlining of the canopy itself,then streamline the roll bar hoop.You can use airfoil-shaped foam rubber,taped onto the tubing.
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*Nose: yes,the delta-Cd -0.14% nose is perfect for you!
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*'Fish',yes,as Freebeard has already mentioned, fish ,birds,traditional airfoils,and streamline bodies will have their thickest section within their first 1/3rd of length.This allows 2X the distance to decelerate the flow back to unity,with zero separation and full pressure recovery.
Speed Demon evolved from the Ack Attack car which was inspired by a Coho Salmon fish.Burt Munro's Indian motorcycle streamliner is very much like a trout fish
If you cannot do this taper,then just do straight sides,like many of the submarines,back to the point where you can begin the boat-tailing.

[freebeard]

yikes = disgust?

Quoth Google: "expressing shock and alarm, often for humorous effect."

[botsapper]

Retro Special Indy roadster-like

http://i.imgur.com/6dpjsqb.jpg

http://i.imgur.com/E9doEqM.jpg

[freebeard]

Nice. How do you think that compares with the 2300mm overall length limit? How about a blunter nose and a longer tail with a flat truncation.

[orengomotors]

Freebeard, do you like the nose shape?

[freebeard]

It looks about right. My concern is that if/when you try to get a smooth surface, the two kinds of foam will fight you.

[orengomotors]

i had a lots of exams and studying this week, but i done some work to the project:




finally, is taking shape!!