How much hp???

[Rex Schimmer]

Dan,
The "classic" tank say a P38 300 gallon has, by itself, a Cd of around .1-.15 but the real challenge are the wheels and all of the other "stuff" that is hung out in the air. Things like round axles, radius rods, spindles, wheels and tires will add up to much more drag than the tank itself. It is legal to stream line all of these parts right out to the inner  surface of the tires. Remember when you do the HP to Cd to MPH calculation the relation ship of the Cd to HP is direct so if you decrease the Cd by 10% it will have the same affect as increasing the HP by 10%. The real fast guys are concerned about both Cd and HP.

Rex

[jacksoni]

"Remember when you do the HP to Cd to MPH calculation the relation ship of the Cd to HP is direct so if you decrease the Cd by 10% it will have the same affect as increasing the HP by 10%. The real fast guys are concerned about both Cd and HP. "

Sorry, I was wrong previously but this was discussed in the following thread.


http://www.landracing.com/forum/index.php/topic,7752.0.html

But reducing Cd is free horsepower, that is for sure. Ok, not free free, but we assume everyone builds their engines to as much power as we can so money spent on reducing Cd (and frontal area for that matter)  pretty much equates to a bigger motor.

[jl222]

 I am new to the site,just got a belly tank. I was looking at classes for lakester. How much h.p. do you guys think it takes for a bellytank to go 250,275,300mph. Any input would be appreciated.. Thanks Dan Parker

Welcome to the site Dan,

Careful what you ask for........     Who's tank did you get? Has it run before? How fast do you want to go?

depends on the type of tank but one needed ~1050 to go 300 & ~ 775 to do 285.
Don't forget YMMV.

   If the hp and mph are known, all that is needed for the BonnevillePro to calculate the cd is the frontal area.
  You just keep inputing cd's untill the known speed matches. Also the gearing and tire size has to be close, but that's one of the cool things about the program, just change it with the keyboard.

                               JL222