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  #1  
Old 11-01-2021, 07:51 AM
jcarne's Avatar
jcarne jcarne is offline
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 2,325
Default Anyone tried covering up the new Van's cowl louvers?

I'm running in the low 300s on CHTs and it's only 29 degrees outside. Probably going to have to restrict some exit area.

I suppose it would be an easy experiment for me to just do but has anyone tried covering up the Van's cowl louvers? How much if any change was noted? I have been toying around the idea of putting electric cowl flaps in their place but don't know if its worth the expense/gain.

Thanks!
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PPL
RV-7A Flying as of 03/2021

Last edited by jcarne : 11-01-2021 at 10:25 AM.
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  #2  
Old 01-24-2022, 03:04 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,499
Default Louvers

Quote:
Originally Posted by jcarne View Post
I'm running in the low 300s on CHTs and it's only 29 degrees outside. Probably going to have to restrict some exit area.

I suppose it would be an easy experiment for me to just do but has anyone tried covering up the Van's cowl louvers? How much if any change was noted? I have been toying around the idea of putting electric cowl flaps in their place but don't know if its worth the expense/gain.

Thanks!
Jereme
What did you end up doing?
I'm considering the Antisplat electric louvers but don't want to add the weight.
Also dont want a mechanical control.
If they aren't needed, maybe best not installed.
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Larry Larson
Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog: http://wirejockrv7a.blogspot.com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #3  
Old 01-24-2022, 04:43 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,973
Default

Larry, I would opine that the standard cooling exit provides adequate cooling unless you're going with a hot-rod setup. If you want to optimize things, there are plenty of things you can do (see Dan Horton's cooling threads), but if you're just looking for reasonable cooling performance, the stock setup should be fine.

Louvers are a draggy way to add exit area and cooling airflow.
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Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #4  
Old 01-24-2022, 05:23 PM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,200
Default Louvers

I believe that Vans made the louvers a standard part of the -A kit when the new style nose gear and engine mount was introduced, presumably to counter the additional obstruction in the exit area.

I would consider an adjustable blanking plate simply installed with screws over the louvers. It may be necessary to adjust it a couple of times per year, according to the seasons, or even only for initial setup.
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Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build
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  #5  
Old 01-24-2022, 05:26 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
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Quote:
Originally Posted by PaulvS View Post
I believe that Vans made the louvers a standard part of the -A kit when the new style nose gear and engine mount was introduced, presumably to counter the additional obstruction in the exit area.
Good info. I haven't seen an example of the updated nosegear kit.
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Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #6  
Old 01-24-2022, 05:31 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,499
Default New Nose Gear

Quote:
Originally Posted by Kyle Boatright View Post
Good info. I haven't seen an example of the updated nosegear kit.
Yep. That's why I was curious what Jereme did. He has a virtually identical A model as mine including the engine.
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Larry Larson
Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog: http://wirejockrv7a.blogspot.com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #7  
Old 01-24-2022, 08:43 PM
Finley Atherton Finley Atherton is offline
 
Join Date: Nov 2005
Location: AUSTRALIA
Posts: 788
Default

Quote:
Originally Posted by Kyle Boatright View Post

Louvers are a draggy way to add exit area and cooling airflow.
Did not do any accurate testing but installed one louver on an already flying 9A and speed seems the same??
Fin 9A
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  #8  
Old 01-24-2022, 09:10 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,973
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Quote:
Originally Posted by Finley Atherton View Post
Did not do any accurate testing but installed one louver on an already flying 9A and speed seems the same??
Fin 9A
The difference won't be big given the overall small size of Van's louvers (the difference might not be measurable without a lot of effort), but ejecting air at low velocity into the freestream is draggy. Beyond that, a bunch of little slots are less efficient than one larger opening. Drag reduction adds up - a little here and a little there, and eventually the difference will be apparent.

I look at louvers as an expedient way to add cooling to an existing cowl or cowl design where you don't want to re-tool.
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Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #9  
Old 01-24-2022, 11:05 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 2,432
Default Me thinks

I think the louvers on the new nose geared RV7A/9A might be less dragging than having the exit air flow thru the center area of the old style nose gear with all the stuff hanging there, not to mention the poor corner radius at the transition from the firewall to the bottom skin.
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2022, worth every penny

RV9A- Status:
98% done, 2% left to go
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Electrical/Panel done
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  #10  
Old 01-25-2022, 05:15 AM
Mconner7 Mconner7 is offline
 
Join Date: Feb 2018
Location: Bradenton FL
Posts: 201
Default

I replaced the louver in one side of my -10 with a cowl flap from anti-splat. I was surprised that it does not seem to make any difference in cooling and only costs about 2 knots in cruise speed when open.
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