DRAG.....Help please
 

How much drag is there on a 8inch sphere at 200mph also at 100mph at sea level in a wind tunnel ,,also a 10inch sphere ...same critiria.....thanx in advance...TROU

RE: DRAG.....Help please
 

The sphere will be in a Reynolds range of 620k to 1,550k which is well past separation. At 100mph the Cd is about 0.1 and climbs to 0.2 at 200mph. Therefore the drag force for the 8" sphere at 100 would be .88 lbf and at 200 would be 7.12 lbf. The 10" sphere at 100 would be 1.38 lbf and at 200 would be 11.12 lbf. You could drop the Cd substantially through streamlining. The sweet spot for streamlining is a thickness/chord ratio of 0.25...

Whats it for?

RE: DRAG.....Help please
 

THANG X for the reply C C i do value your input ....however what is lbf ?? please.......OR how much thrust requierd to push a 10inch / 8inch smooth ball at 100 and 200 mph at SL..

RE: DRAG.....Help please
 

Sorry, lbf is a force read "pounds force" to distinguish it from "pounds mass". Ye Olde English Units can be a bit confusing but at least we don't have shillings to deal with - Jefferson got the money right. Anyway, you would need an equal amount of thrust to propel the sphere at the given velocity and diameter.

RE: DRAG.....Help please
 

Thanx again CC im realy hopping for some hard numbers... since i dont have force thrust or drag.....

RE: DRAG.....Help please
 

Let me try this again. Drag force is the same as the thrust force needed to propel the sphere at the constant speeds you asked about. So, the numbers I gave you are the thrust required to push the sphere at that speed. An 8" sphere traveling at 200 mph requires 7.12 pounds of thrust to maintain that speed at sea level. Thrust force = Drag force. OK?

RE: DRAG.....Help please
 

Thangx mate presheat that.......just gut feeling no math at all i guest 25lbs ish for 8 inch spere at 200 mph