Quote:
Originally Posted by rmay635703
But do you? This forum is about aero.
Thats why assuming a CD of 0.14 and a frontal area of 16sqft results in a much better result that all here would appreciate far more than a CD of .38!
200hp for 200mph, Now that would be an achievement I could take to the bank!
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The published drag coefficient for the outgoing Mustang GT500 is around 0.38, the newer one may be a little bit sleeker, but yes if you were to reduce the frontal area or the drag coefficient it would become much more aerodynamic and would also require less power to travel at the same speed. However unless you were able to use unlimited resources to mass produce this mythical car with a drag coefficent of only 0.14 and a frontal area of just 16ft as a single seater, or perhaps a tandem two seater it might be possible to achieve higher speeds with less horsepower, however given the constraints placed on manufacturers by the governments as well as the demands of consumers for more comfortable as well as powerful cars they tend to not do this except as a technological show piece/ concept car, although currently the limit was nearer to 0.18 or 0.2 on the show circuit for their high mpg concepts, however none of those had barnstorming performance.
As I was trying to illustrate earlier the road load power required to overcome the aerodynamic drag force is a function of the vehicle's speed to the third power. This has been proven to be reasonably accurate.
The road load force calculation looks like this:
frl1=fr*w*cos(phi)+0.5*cd*(rho)*(af)*vm.^2 + w*sin(phi)
Where frl= road load force, fr= rolling resistance coefficient, w= weight in newtons; i.e. the mass in kilograms* the gravitational constant of 9.81 m/s^2, phi being the grade the vehicle is on in radians + 1/2* the drag coefficient * the density of air* af= frontal area *vm (the velocity in m/s^2) + the weight in newtons * the sine of the grade angle in radians
To calculate road load power you multiply the road load force equation by the velocity in meters per second and the result is in Watts or Kilowatts in the S.I. unit system, however if you used the English units you would end up with horsepower.
I might not know the best way to reduce the aerodynamic drag of a vehicle, having only touched upon the fundamentals in my automotive mechanical engineering coursework, but I do understand that a smaller frontal area, cleaner air flow and a smaller stagnant pocket of air behind the car can help it slip through the air better. My car had a damaged under tray, the bolts that held it on had been broken in half, so I had to improvise by making an air dam to help prevent it from flapping while in motion, and do you know what, it actually helped regain some of the lost fuel efficiency, it would be better if I could actually take the car and put it on a lift and drill out the bolts and replace them so that the under tray is also properly installed while still being removable for oil changes and the like.