REFLECTOR: Retrofit NACA from armpit scoops

[Andrew Judge]

I'm a little concerned about high temps. I seem to have them now (semi
high temps) and want to get the temps right and make it easy to take the
cowlings off. I also have a second oil cooler, but both cyl and oil seem
a little high.

 

Maybe I can keep the scoops and cut those out of the cowling and fasten
them permanently to the wing roots?

 

Thanks!

 

Andy

 

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Chuck
Sent: Monday, October 26, 2009 1:06 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Retrofit NACA from armpit scoops

 

Andy, I switched from the armpit scoops to the overhead NACAs when I
switched from the Mazda 20B to the IO360. It wasn't that big a job, but
it does take some time to repair the lower cowl and to cut and paste the
fuselage to accept the NACA ducts. Initially I had cooling issues with
the NACAs until I tightened the plenum clearances and added 5/8" VG's. 

 

I'm just finishing adding a turbo and a second oil cooler (factory)
which mounts in-between the inlet NACAs. I've added the factory 3" oval
air scoop to the upper cowl that feeds directly to the oil cooler, but
is not totally sealed to the oil cooler face. I did this because I was
getting a pretty hot upper cowl and I think this will help force cooling
air into the upper area and when shutdown will release hot air out of
the scoop opening. I went with a scoop because the boundary layer is
pretty thick that far back on the fuselage and I wanted to get clean
air. I'll be doing taxi testing soon and will let you know how it works.


 

By the way, you can get the factory scoop in either fiberglas ($35) or
carbon fiber ($45). I'm using the carbon which is stringer, lighter and
has a smaller opening profile.

 

Chuck H

 

From: Andrew Judge <mailto:ajudge at grovenetworks.com>  

Sent: Sunday, October 25, 2009 9:32 AM

To: reflector at tvbf.org 

Subject: REFLECTOR: Retrofit NACA from armpit scoops

 

 

I was wondering if anyone on the list done the change from armpit scoops
to NACA cooling?

I really want to make the change due to maintenance and cooling on my
Standard Fixed. The SCAT is killing me every time I have to remove the
cowlings.

If so, what difference in ease of maintenance, cooling and speed (if
any) have you noticed? I'll probably do the down exhaust too.

I also have a second oil cooler aft. How do you route air into that?

Andy Judge
N55AJ
KTMB 

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