Trevor Jordan writes:
>Close, but not quite. Exponential is n^^x, not x^^n (where n is 2 or 3 in
>this instance). Actually I believe that your original suspicions were
>correct and the load will fall between the square and the cube of the
>speed. The work done will be a cube function, but the losses (drag, etc)
>will be a square of the speed. I have no idea of the relative
proportions.
Actually, saying that the mechanical drag increases with the square of the
speed assumes that the force required to turn the fan increases with the
speed. But I think that the force is constant which would make the load
due to the bearings and oil seals is constant which would make it
porportional (n^^1). They would also be trival or else the heat build up
would
cause a rather quick melt down. The power required to pull the belt around
the pulleys, however is another issue.
>An important apsect that has not been raised is how much power gets to the
>rear wheels in the first place. A carb TR6 develops about 105 hp at the
>flywheel. If 95 get to the wheels then another 5 from an electric fan
>represents a 5 per cent improvement. If only 50 get to the wheels then an
>electric fan represents a 10 per cent improvement. Any suggestions?
That is also a point of interest. What ARE the losses in the drive train.
Remember
the oil pump in the overdrive draws power, too! But then are the HP
ratings figured
with the fan attached. If I am not mistaken, the HP ratings are the
ratings with all the
necessary attachments (Exhaust system, muffler, alternator, water pump,
fan) and
removing the fan can actually allow you to realize an output greater than
rated.
Dave Massey,
St. Louis, MO
57 TR3
71 TR6
80 TR8
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