Subject: [FlyRotary] Re: K&M and Thick Radiators


> Posted for "sqpilot@earthlink" <sqpilot@earthlink.net>:
>   Hi, Ed....I am going to go normally aspirated.  Keep it simple approach.
> I'm hoping to cruise closer to 7 to 8 gallons per hour at cruise at
> altitude, whatever speed that may give me. My aircraft is pretty clean
(low
> drag), so I should be able to get a decent cruise at those fuel burns?  I
> might just go with a radiator that is 18" x 6" x 4"deep, and settle for a
> lower rate of climb.  My SQ2000 with a Lycoming is supposed to climb at
2500
> fpm.  (I flew in the factory SQ2000, and we climbed between 2200 and 2400
> fpm up to 8000 feet).  So, If I have to settle for a lower rate of climb,
it
> should still outclimb any of the Cessnas I have owned. Thanks again for
your
> input, Ed.     Paul Conner>
>
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Ok, Paul.  Based on my back of the envelope calculations at a fuel burn of
8.5 gph with that size radiator, you would need an airspeed of around 142
mph to provide adequate air mass flow.  So it should have no problem cooling
you at your typical cruise airspeed provided your ducting brings in the air
stream adequately.  So, I would think you need to concentrate on how you
would handle the heat rejection defficit between take off and 142 mph.  I
have no idea how long it takes your type aircraft to go from application of
take off power to 142 mph.  That could make a big difference in how much of
a challenge your high power/low airspeed regime is. Cowl flaps? Spray bars?

Good luck.

Ed Anderson



Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com