REFLECTOR: Vortex generators location for armpit cooling scoops

[Andrew Ellzey]

Larry,
 
So that is the question, how tall are your vortex generators, how far out in front of the armpit scoops did you place them? Did you make them, or buy them and if you bought them, where from. Can you please send a photo. 
 
Thanks,
 
Andy


>________________________________
> From: Laurence Coen <lwcoen at hotmail.com>
>To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org> 
>Sent: Wednesday, August 14, 2013 6:25 PM
>Subject: Re: REFLECTOR: Vortex generators location for armpit cooling scoops
>  
>
>
>Andrew, 
>
>I have armpit scoops on my SR/RG that look just like yours.  When I 
mounted them I was concerned about the boundary layer and extended the scoops 
3/4" out from the fuselage so the entire scoop is outside the boundary 
layer.  I also added an insert that looks like venturi that in theory 
should help with pressure recovery.  The fact that I don't have cylinder 
head cooling problems doesn't mean that it will work for you.  I am down 
draft cooling a 220 HP Franklin.  I have vortex generators ahead of my oil 
cooler inlet and that did lower my oil temp.  If you try vortex generators 
I would suggest that they be tall enough so they stick out of the boundary 
layer. 
>
>Larry Coen 
>N136LC 
>
> 
>From: Andrew Ellzey  
>Sent: Wednesday, August 14, 2013 3:50 PM 
>To: Velocity Aircraft Owners and Builders list  
>Subject: REFLECTOR: Vortex generators location for armpit cooling 
scoops 
>
> 
>I am still battling a high CHT at cruse on my # 5 cylinder on my updraft 
IO-540-E1A5, 300HP Lycoming engine. I can do full power climb outs in the 
pattern all day without any issue. From everything that I have read on this 
subject on the Reflector, this is common with the arm pit cooling.  The 
higher pitch angle in the pattern, and in a cruse climb, forces plenty of 
cooling air into the scoops, but the cooling ability drops off in level cruse 
fight attitudes. My question is, is there anyone left on the reflector that is 
using the armpit cooling, and do you have vortex generators in front of your 
armpit scoops to help the airflow boundary layer adhesion to this area forward 
of the armpit scoops? If you have vortex generators, what size, location, did 
you make them, buy them, can you send a photo, please. 
>
>I have swapped and calibrated my CHT probes, swapped the lowest CHT 
cylinder fuel injector with my #5 injector. Nothing helps, it seems to be tied 
with airflow into my scoops, or airflow inside my lower cowling. If the addition 
of vortex generators doesn’t  help, I will probably have to install some 
additional baffling to redirect more air to the aft two cylinders, #5, and #6. 
Cylinders 1, 2, 3, and 4 are getting plenty of air, in fact they are running 
cooler than I like at this time, but until I can get #5 CHT under control, I 
can’t lean my engine properly to know if I have adequate airflow for all 
cylinders or not. Installing my gear doors seemed to help. 
>
>Photo attached showing my armpit cooling scoops. The additional screws 
under the armpit scoops, attaches a mating internal scoop that directs the 
airflow to my aft lower cowling.   
>
>Thanks again for your help, 
>-----------------------------------------
>Andrew 
Ellzey
>N151AJ 10 hours into Phase 1 testing 
>
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