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Old 02-01-2013, 09:22 PM   #47 (permalink)
mort
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Quote:
Originally Posted by sendler View Post
So let's say we take the motorcycle drive train away and replace it with a ducted fan which is geared to run best at the power peak of the engine and has the same efficiency throughout the speed range of the test. Discounting air resistance and any losses on the vehicle, and holding 100 hp constant from the engine. Will we have constant values for thrust and for acceleration to the IFoR of the rider?
Hi sendler,
No.
Thrust and acceleration measure the same thing. When thrust = the weight of the bike the acceleration is 1 g. As the speed increases the thrust will fall.
This is almost an airplane propeller for which the basic formula reduces to this:
Thrust = ( HP * eff * 375 ) / air speed (mph)
and looks like this:


The figure shows a plot of the thrust generated by a particular (variable pitch) propeller as a function of the airspeed (15 through 240 MPH) and power applied to it (250 through 500 HP). The propeller is less efficient at low speed.
Source
-mort
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Last edited by mort; 02-01-2013 at 09:54 PM..
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