REFLECTOR: Scoops

[Al Gietzen]

Subject: Re: REFLECTOR: Tim England Chevy V6/Water Cooling Video

 

Chris, 

 

My cooiling system has (2) radiators. (3 if you count the big heater
core/boost cooler in the nose.) 

 They are both fed by NACA scoops, one on the top and one on the bottom.
Origonally, I planned on having both on the top, but the finished fuel
injection didn't leave me enough space. 

 

I just can not stand the sight of a sexy airplane like the Velocity or
SQ-2000, with scoops hanging out all over the place. There has to be a
better way, and I'm sticking with that thought until I proove myself right
or wrong. 

 

Kurt Winker

 

Kurt;

 

I agree that scoops "hanging out" on a sleek airplane doesn't look all that
great; so it'll be great if you get adequate cooling from the NACA's.  What
is the total x-section area of the scoop inlets for the rads; and the exit
area from the cowl?

 

I think it is also worth noting that "looks" and "cooling drag" don't
necessarily equate.  It is mostly about the energy of the air taken on
board, and the energy of the air leaving.  The higher pressure recovery
efficiency of the ram scoop leaves more energy to accelerate the air before
it's exit; so if everything else is done right, the cooling drag can be the
same or less than using a NACA; at least for our speeds.  Since it is
difficult for us to get ideal exit ducting from the cowl; if you can get
sufficient pressure recovery from the NACA to get that air through the heat
exchanger then you're in good shape. 

 

Since the effective ram scoop is protruding out there, it is necessary to
shape it such that it doesn't leave a turbulent wake; and, less importantly,
deal effectively with the boundary layer diversion.  It's that boundary
layer that messes with the effectiveness of the NACA.

 

Air flow is tricky business and full of surprises; so short of wind tunnel
tests; we'll know when we fly.

 

 FWIW,

 

Al

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.tvbf.org/mailman/private/reflector/attachments/20041202/9e986839/attachment.htm