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Ah yes. But I was thinking of a turbo engine
making full power up to 25K. Which of course destroys the symmetry of the
math.
So I restate.
If at X mpg IAS at 2000' you can get rid of Y
BTU heat
Then can you get rid
of Y BTU heat at X mph IAS at 25K'
If IAS is a direct measurement of Air Mass then
yes, as the Air Mass is the same.
If not then IAS is not a direct measurement of Air
Mass.
Or my logic is faulty.
Thanks for your tolerant
indulgence.
----- Original Message -----
Sent: Monday, December 08, 2003 11:25
AM
Subject: [FlyRotary] Re: Air Density at
altitude
But of course, with only 47% of air mass flow through the
radiator, you also have only 47% of air mass flow through the engine
and 47% as much heat to reject. So, for an NA engine, there shouldn't be
a significant change in the ability of a cooling system.
Or so it seems to
me .... Jim S.
Ed Anderson wrote:
Found a table of air density vs Altitude
Sea level Density = .00237 Slug/Ft^3
Density at 20,000 = 0.001267
Slug/Ft^3 or a 47% decrease
So taking formula for air mass W = p*V*A with p 47% less than at
sea level
means you would get 47% less air mass flow (with the same
cubic feet/minute
of air volume flow) at 20,000 ft compared to what you
would get at sea level
for the same volume flow.
While cooler temps would help, it would not compensate for a 45% less air
mass flow.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
>> Homepage: http://www.flyrotary.com/
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--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity
N4095T
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