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I read an article (don't remember where) about a fellow who placed two vortex generator tabs just in front of the NACA ducts. This improved efficiency quite a lot. He had to experiment a while to get it right; but, liked the results. I think it was on a Velocity or Cozy.
This makes perfect sense. As I remember when I read the initial NACA report. The paper indicated that the duct was efficient for large volume flows which created little back pressure. Thus, my analysis of the operation is that the efficiency of the duct depends on a bit of local turbulence at the duct to break the local boundary layer. A high flow rate, as the original paper indicated and/or required, would do that. Also a set of vortex generators in front of the duct would also do the same.
Second point: I believe that a reversed direction NACA scoop would make an excellent low drag exit port for the cooling air stream. Such a scoop design would tend to form a small low- drag partial vacuum at that point, allowing the exit scoop to literally help suck the air out. This would improve cooling efficiency I.E. NACA in, and ACAN out. I hold several patents, but I am not going to pursue this idea on that basis. I think it has a good possibility of being a very efficient low drag cooling system.
If anyone tries it, please let us know your findings.
Best Regards;
James Freeman
David Staten wrote:
I skimmed it.. Chris and I are actually considering armpit scoops for cooling, but we still have this nagging urge to minimize deviations from plans. I will go back and do more than just skim..
All I saw was NACA's, Cooling and immediately thought of PL..
Dave
Bulent Aliev wrote:
You are right Bill. David did not read the whole article. Or he didn't want to hear it? :)
Buly
On Mar 9, 2006, at 8:58 PM, Bill Dube wrote:
I read that article as well. I had the same skepticism about the NACA intake for cooling. My understanding is that with an NACA inlet, you don't get the ram pressure you need to force air through a high fin-count radiator. Am I wrong about this?
Bill Dube'
David Staten wrote:
At the risk of invoking PL's name, anyone else read this months Sport Aviation mag from EAA, and notice an article on cooling that seems to indicate that NACA's are acceptable and adequate for aircraft cooling needs? I have no idea regarding the authors credentials, and I no longer monitor PL's "newsletter".. I was curious more than anything else... Pauls reaction, others reactions, etc.
Translation.. yes.. I'm stirring the pot/Trolling... I figure if we are using NACA's on the Velocity, that makes us somewhat of a NACA supporter..
Dave
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