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Re: Fans revisited

To: Randall Young <randallyoung@earthlink.net>
Subject: Re: Fans revisited
From: Trevor Jordan <tjordan@vic.bigpond.net.au>
Date: Mon, 15 Mar 1999 21:50:24 +1100
Cc: triumphs@autox.team.net
References: <v04011700b3123a62d0b4@[24.192.18.180]>
At 8:37 PM +1100 15/3/99, Randall Young wrote:
>I don't have my old calculus book handy, but I'm pretty sure Y=X^2 was
>the very first example of an exponential function.

"An exponential function is defined as:

y=b^^x, b>0

where the base b is a positive constant and the exponent is a variable"

Fundamentals of Technical Mathematics with Calculus, Second Ed, p295.
Arthur D Kramer, Professor of Mathematics, New York City Technical College,
City University of New York

>And, the losses between the flywheel and the road are probably mostly
>proportional to power.  So, for your example of 105hp at the flywheel
>and 95 at the rear wheels, an added 5hp at the flywheel would add only
>4.5 at the rear wheels.  IOW the percentage increase is the same,
>whether measured at the road or at the flywheel.

Why would they be proportional to power?  Most of the losses should be
friction or turbulence and proportional to speed.  However, the friction
losses may increase as the load on the gear trains increases with the
application of power.

>I believe the drivetrain losses are a lot closer to 10% than 50%.
>Otherwise, the diff & tranny would get a lot hotter than they do, and
>need more cooling.  I've seen the measurements somewhere, just can't
>remember where.

Ten per cent loss in a gear train sounds about right.

>OTOH, it's worth noting that most car manufacturers now use ATF instead
>of 90W, apparently to reduce friction to the oil.  The racers seem fond
>of 5W synthetic gear oil, but again I have no hard numbers on how much
>difference it makes.

This is probably the usual compromise between performance and life span
that racers normally have to make.  But it sounds like much of the loss
must come from moving the lubricants around.

Trevor Jordan
74 TR6 CF29281U

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