Thoughts about air scoops.

[ronlock]

I set up my cowls with 2 times the exit air area, as intake area.
A backwards scoop would work for exit air.   

So does a scoop that projects into the cowl - sort of 
an intake scoop, installed backwards, and on the inside 
of the cowl.   With a glas cowl, they are fairly easy to make.   
For a 1/2 inch wide exit air scoop, pick a spot to rear of engine, 
and plan to cut out a rectangular piece out of the cowl, about 
1/2 inch wide,  about 2 to 3 inches long (longitudinal direction).  
Cut ONLY the two long sides, and the 1/2 inch side to rear.   
Push the front end of the cut glas into the cowl about 3/8 inch.
Install two hard balsa triangular pieces at each side, 2 to 3 
inches wide, and 3/8 at base of triangle.

Or,  you can cut the front end of the rectangular scoop shape, 
and make an air intake scoop.

Later, Ron Lockhart
  ----- Original Message ----- 
  From: Adam Quennoz 
  To: Pattern List 
  Sent: Tuesday, February 04, 2003 8:34 PM
  Subject: Thoughts about air scoops.

  It seems the trend these days are air scoops.  Before a scoop is effective, the area of the air exit must equal or exceed that of the air intake thus allowing a positve air flow to occur.  With all the scoops people are putting on the nose of the aircraft, there must be a pretty good sized hole somewhere for the air to escape.  There are cheek scoops, chin scoops and now with the concern of cooling the crank cases, there are scoops above the engine compartment.  I call them "nose scoops".  

  Has anyone thought of making EXITS on the top of the nose above the engine, and/or exits on the cheeks?  Basically put the scoops on backwards.  The air flowing over the backward facing scoop would actually create lower pressure inside the engine compartment allowing a larger volume of air to enter the chin scoop.  The air entering the chin scoop can flow all around the engine as it makes way to the exits of the engine compartment, and what's left can flow down the pipe tunnel.  

  I'd like to hear what others have to say about this idea.  I'm thinking of trying it on my pattern plane.

  Regards,
  Adam Quennoz
  AMA 383866
  IMAC 2439
  NSRCA 3546
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