Furze Platt Greenpower Racing

Aerodynamics in a nut shell or in this case a bubble. 

Rolling resistance and wind resistance using the pink line which approximates to Turbo Tortoise. 

At 9 mph wind resistance is 6 watts, rolling resistance is 26 watts                        total 32 watts = 1.33 Amps at 24 Volts

 At 19 mph wind resistance 55 watts, rolling resistance is 55 watts                        total 110 watts = 4.6 Amps at 24 Volts 

At 25 mph wind resistance is 120 watts,  rolling resistance is 72 watts                 total 192 watts = 8 Amps at 24 Volts

 At 30 mph wind resistance is 221 watts,  rolling resistance is 88 watts total 309 watts = 12.8 Amps at 24 Volts 

At 35 mph wind resistance is 335 watts,  rolling resistance is 101 watts total 436 watts = 18.2 Amps at 24 Volts

 At 38 mph wind resistance is 442 watts,  rolling resistance is 111 watts total 553 watts = 23 Amps at 24 Volts

 So doubling the speed increases wind resistance 8 times, 2 to the power 3 a cubic function, but only doubles the rolling resistance, 2 to the power 1 a linear function.

Halving the car weight will halve the rolling resistance values but won’t affect the wind resistance.

So to go fast you must look at the shape first. 

The yellow lines are for a worse car, the blue for a better car. 

http://www.soton.ac.uk/ses/outreach/greenpower/index.html

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Last modified: 08/06/09