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  #1  
Old 03-18-2017, 08:33 AM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 64
Default Where to put NACA scoop

Hi guys looking for some advice on where to put the NACA scoop on my -4. I have read all the previous -4 related posts in regards to this and have heard some great ideas but no follow ups on if the alternative locations worked with good airflow. I'm trying to maximize foot room so looking for alternative location to the stock Vans location of under the cowl cheek. Does anyone have a NACA scoop anyplace other than below the cheek? After reading a post about a simple hole drilled in front of the canopy I'm considering installing a single NACA scoop centered in that avionics top skin just in front of the canopy and splitting it to both air vents, I would just make a plug to keep rain out on the ramp. Would really appreciate any first hand knowledge before I go guessing at pressure areas and cutting.

Thanks
Shawn.
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  #2  
Old 03-18-2017, 08:54 AM
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acam37 acam37 is offline
 
Join Date: Aug 2012
Location: Lufkin Tx
Posts: 543
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Have you sat in a -4 with the stock vent locations? We put NACA vents on both sides under the cowl cheeks and they were fine. Leg room was not an issue
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  #3  
Old 03-18-2017, 09:20 AM
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Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 416
Default NACA locations

A friend that led me to decide on a -4 for my current project reports excellent results with vents under the cheek cowls in contrast with some reports( Panther and RV-3) of negative pressures on top of the wing. Also, my friend has a vent on the bottom of the wing for the rear passenger with excellent results.

Like the OP, I considered a couple small NACA in front of the canopy ( guaranteed to deliver lots of air ) but needed fast relief on my flying -3B so installed a -10 vent under the top longeron and get LOTS of air in -3B cockpit.
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  #4  
Old 03-18-2017, 09:34 AM
Skysailor Skysailor is offline
 
Join Date: May 2011
Location: Atlanta, GA
Posts: 144
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My 4 has a NACA scoop in each cheek cowl extension. Everything glasses together well and since the scoops are lower than centerline rain is not an issue. I also have one under the right wing for the rear seat. All provide huge amounts of air.
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  #5  
Old 03-18-2017, 10:38 AM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 64
Default

Thanks guys for the responses! It's truly appreciated. I have been losing lots of sleep over where to put these NACA scoops.

Quote:
Originally Posted by acam37 View Post
Have you sat in a -4 with the stock vent locations? We put NACA vents on both sides under the cowl cheeks and they were fine. Leg room was not an issue
Believe it or not I have never actually sat in a -4. This might sound dumb but I would also like to keep the NACA scoops off the side walls below the cheeks for aesthetics on the inside. My wiring is all nicely hidden and at the moment my side walls are all clean, I just figure if I can move the NACA scoop it might help the foot area "feel" bigger. I do live in AZ though so air flow is the main priority with looks second. I will put the scoops in the factory spot if need be.

Quote:
Originally Posted by Larry DeCamp View Post
A friend that led me to decide on a -4 for my current project reports excellent results with vents under the cheek cowls in contrast with some reports( Panther and RV-3) of negative pressures on top of the wing. Also, my friend has a vent on the bottom of the wing for the rear passenger with excellent results.

Like the OP, I considered a couple small NACA in front of the canopy ( guaranteed to deliver lots of air ) but needed fast relief on my flying -3B so installed a -10 vent under the top longeron and get LOTS of air in -3B cockpit.
Glad to hear below the cheeks is a high flow spot, I had also read a few posts about low air flow and was a bit worried. I will also be doing a below wing single scoop to feed the back seat air vents.

Quote:
Originally Posted by Skysailor View Post
My 4 has a NACA scoop in each cheek cowl extension. Everything glasses together well and since the scoops are lower than centerline rain is not an issue. I also have one under the right wing for the rear seat. All provide huge amounts of air.
This sounds great! I would love to just glass the scoops into the cheeks. Would you happen to have any pictures of this?
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  #6  
Old 03-18-2017, 11:05 AM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 64
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Guys here is picture of cockpit with my eyeball vents installed if anyone sees a great idea on a out of the way place to install the scoops. I built my avionics rack with two 2" spots available on either side to run the Scat tubing up behind the panel if need be.

[IMG][/IMG]

[IMG][/IMG]
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  #7  
Old 03-18-2017, 12:00 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 1,791
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My current -4 didn't have rear seat air when I bought it. I bought the RV-10 vent kit (small, 'push out' rectangles) & installed one just behind the roll bar bulkhead & a few inches below the canopy hinge on the right side. Flow is fine.

Front is NACA under the cheek but I wish it wasn't; the SCAT hose always seems to be in the way when I'm adding/subtracting accessory avionics.

It's been a really long time, but IIRC, the 1st -4 I bought had NACAs for both front & back mounted in the canopy skirt. I need to find some old pics to be sure, though.

Charlie
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  #8  
Old 03-19-2017, 07:12 AM
Skysailor Skysailor is offline
 
Join Date: May 2011
Location: Atlanta, GA
Posts: 144
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Pictures sent via email.
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  #9  
Old 03-19-2017, 10:43 AM
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SMO SMO is online now
 
Join Date: Oct 2007
Location: Salmon Arm, BC
Posts: 844
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Another option is to put the inlet right at the wing root on the leading edge. In the picture below you can see my air inlet there (idea shamelessly copied from others). Behind the air inlet it turns 90* into the cabin at floor level behind the panel bulkhead, then 90* again to go upward, splitting to the eyeball vents placed similarly to yours. To get the room to do this required turning the forward wing attachment bracket around so the angle web faced rearward. Not sure if this would work on a -4. No lack of air!

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  #10  
Old 03-21-2017, 06:54 AM
Michael Henning Michael Henning is offline
 
Join Date: Jun 2011
Location: Nashua, NH
Posts: 368
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I used two RV-10 vents, one on each side. Huge amounts of air, and simple. For the back seater I have to Vetterman vents, great air there too.
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