REFLECTOR: The use of VG to aid cooling

[Kurt Winker via Reflector]

Tested the same ones on my system. Now, my NACA scoops feed radiators & oil coolers, but I needed something and gave it a shot. 
I have. 173-elite with XL size NACA scoops. Seems like this airframe has more curve in both directions... 
Using them per the old Velocity Views structions, I saw almost 30-degrees drop in temps. 
A friend and homebuilder of more than a dozen aircraft (as well as a retired flight test engineer) loaned me some single-piece aluminum VG sets that were almost twice as tall. I thought it was worth a shot. The temps went back up about 25-degrees. 
My theory is that they are wider apart, and I think they caused the flow to go around the scoops, instead of into them. 
Put the smaller individual ones back on, temps went right back Down. 

I would like to try taller individual ones... And will make some later. 
Right now, I'm 'Sperimenting with a couple other things. More to come. 

Kurt

Sent from my iPad

> On Sep 30, 2014, at 19:48, Darrell & Nora Kufalk via Reflector <reflector at tvbf.org> wrote:
> 
> Ron,
> 
> A few years back, I tested the 1/4" tall VGs in front of my NACAs.  I was very careful to position them just as described in the old Velocity Views newsletter.  I used RTV to install them the day before the test.  I flew 25 miles, got some gas, removed them and flew 25 miles home.  Same OAT.  Same power settings.  Same climb rate.  Same altitude.  Same cruse speed.  I downloaded my engine data and carefully studied it.
> I got exactly ZERO degrees lower CHTs between the 2 flights.
> 
> Darrell
> XL-RG IO-540
> 
> 
> -----Original Message-----
> From: Reflector [mailto:reflector-bounces at tvbf.org] On Behalf Of Ron N VelocityXLFG via Reflector
> Sent: Tuesday, September 30, 2014 11:56 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: The use of VG to aid cooling
> 
> Great Job ! . But now I ask the question how is it so many builders claim the small vg's help when your info so clearly says it does not. I have small vg's  in front of my nacas
> and was sure they helped till now. :(   I have now put testing my naca 
> intake back on the testing list. Oh well more fun things to experiment with :-) .
> 
> Great article so loaded with great info.
> 
> 
> Ron
> 
> 
> 
>> On 9/30/2014 8:48 AM, Matt Bucko via Reflector wrote:
>> Well done David.
>> Matt
>> 
>> 
>>> On 9/29/2014 5:09 PM, David Ullman via Reflector wrote:
>>> My Velocity has always run hot.  I have fixed this with the use of 
>>> Vortex Generators aiding the flow of air into the NACA ducts on top 
>>> of the fuselage.  For a full report go to:
>>> 
>>> https://davidullman.com/uploads/THE_USE_OF_VORTEX_GENERATORS_TO_ENHAN
>>> CE_PUSHER_AIRCRAFT_COOLING.pdf
>>> 
>>> 
>>> Comments appreciated.
>>> 
>>> To see recent photos of N444DX hangared in Independence Oregon, go to:
>>> 
>>> https://davidullman.com/VelocityPhotos.php
>>> 
>>> David Ullman
>>> David at davidullman.com
>>> 
>>> 
>>> 
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