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Tracy Crook wrote:
OK, here's my take on the thick vs thin rad argument.
I agree that the thinner radiator is 'more efficient' in terms of
dissipating a given number of BTUs with the fewest square inches of fin area
*IF* the volume of air used to do the job is ignored. This whole argument
hinges on that 'if'. Every thing I have read on the subject of drag
reduction (related to cooling) points to using the *minimum number of cubic
feet* of airflow to do the job, so, my premis is that the name of the game
is using the *least* amount of air to do the job.
So, I see the choice as: Do you want an 'efficient' radiator or an
efficient airplane?
There goes Tracy with all that facts and logic stuff again. 8*)
Interestingly enough, it may be that the Delta's rather unique properties may make it simpler to use the large thin radiator with a much slower airflow than it would be most other. The most insiduous problem with the Delta, as I understand it, is that it has a tendency to be nose heavy. Moving the radiators aft of the passenger seat will relieve the nose of that weight, and put it just behind the center of lift. The peripheral advantage, is that I now have a large volume of otherwise empty space to play with.
Now that I have it back there, the problem becomes one of delivering and venting air. Scoops built into the wheel wells (with NACA scoops built into well doors if I ever incorporate them) will be near the center of the chord line, and one of the areas of highest pressure. The air will continue on and vent through the top rear of the turtle back, near the rudder and elevon control linkages, one of the lowest pressure points. I hope to have an extremely high pressure differential, but I have no way of actually testing right now. The radiator study report that I have read, (http://naca.larc.nasa.gov/ ...do a search on radiator)
A high pressure differential will allow me to have a smaller than expected scoop. If I do a good job of designing and building a duct that will allow the air to expand and slow before it gets to the radiator, it will pass through slow enough to exchange heat efficiently.
Here's a question for the number crunchers. Which will be more efficient:
A)A thick radiator with a high cooling air flow rate?
or
B)A thin radiator with a low cooling air flow rate?
Personally, it's starting to make my head hurt.
--
----Because I can----
http://home.nc.rr.com/deltabuilder
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