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SJordan 01-15-2018 08:09 AM

Vetterman Air Vents on Right or Left side?
Ok guys its been over a year since we last debated -4 fresh air vents so I figure its time for another go,,,, ok not really but I do need some advice. I have read every post I can find on the Vetterman air vents and I still keep finding conflicting informant (from Larry himself) that a vent on the right side will actually suck air out. I want to use two of these Vetterman air vents for my back seat do they really work on both sides?

Thanks for any real world experience with this.

fixnflyguy 01-15-2018 11:16 AM

What I did..
On my -4 I put the NACA style vents on each side under the cowl cheeks for front seat air. I put the eyeball vents straight onto the NACA vent, so I reach down just above my shins to open/close..easy and simple. For the rear seat, I have a NACA inlet on the lower right wing skin a couple ribs out from the fuselage,, and have a 2" SCAT hose that comes back throught the wing/fuselage into the rear stick well with an eyeball vent there. It will blow your hair straight up in back seat. I believe RV-8 plans even show this for backseat cooling air. No vents that open into airstream, and lots of air in the cabin.

spirit49 01-15-2018 01:16 PM


Originally Posted by fixnflyguy (Post 1232384)
For the rear seat, I have a NACA inlet on the lower right wing skin a couple ribs out from the fuselage

A picture of this set up would be awesome. Please

Scott Hersha 01-15-2018 10:03 PM

Another possible solution: run a scat tube (inside the engine compartment) from an adapter on your rear baffle in the center above your crankcase split line to the firewall. On the inside of the firewall, connect a Y adapter to 2 scat tubes feeding 2 eyeballs just below your panel for amazingly good AC.........

spirit49 01-16-2018 12:30 AM


2 scat tubes feeding 2 eyeballs just below your panel for amazingly good AC.........
I think the OP wants to know how to make dedicated rear AC.
Even though you probably have some awesome amount of air up front.....

Scott Hersha 01-16-2018 08:27 AM

Yep..... I missed that part, sorry.

I didn't have any AC for the back seat of my -4 (sold now), but as was said already, an RV8 type rear seat vent might work well. You'll probably have to make a new inspection opening in the bottom of the wing in that area for access, but that should be easy enough, and it works quite well on the -8.

fixnflyguy 01-16-2018 08:59 AM

Back seat air solution
I will try to post pics of my right wing NACA vent and SCAT routing. I lent my build photo album out to a friend, and don't have a way to get the internal pics without opening my plane up. In short, the NACA inlet is AFT of the R/H spar and aileron pushtube, with the SCAT hose running through the lightening holes and I cut a 2 1/4" hole through the fuselage side skin similar to the aileron pushtube cut-out. The SCAT goes into the "tunnel" and comes up behind the front seat,slightly offset to the R/H side of the rear stick. I fabricated a close-out with a boot for the rear stick, and have the eyeball mounted in the close-out. I believe, if you were adding this to a completed aircraft, it could be done without an additional access plate, but it would be a little tedious fitting the NACA duct and getting it secured.

rv7charlie 01-16-2018 09:12 AM

My purchased -4 had no vent for the back seat. I bought an RV-10 vent kit from Van's, which contains the stamped parts for two swing-out vents. Very reasonable price, IIRC. Each vent is ~ 2 1/2 x 1 1/2 inches, plus the perimeter mount. I mounted one on the right side of the fuselage, as high as I could under the top longeron and a few inches aft of the structure under the roll bar. It seems to supply adequate air to the backseater, and doesn't blow in their face, which helps avoid breaking intercom squelch when you have inexperienced passengers.

Very simple to install, very light weight, and I gave the spare to a neighbor for one of his planes.


Brian Vickers 01-16-2018 10:53 AM

Left side
The Vetterman passenger vent on my 4 is on the left side because I was told the clockwise spiral prop wash tends to create negative air pressure on the right side of the canopy skirt area. This has been proven by many early 4 builders that put NACA vents in the skirt on the right side, and they report air is actually being sucked out of the vent, not coming in. The vent in my airplane is about two inches aft of F-406, and about 1.5 inches below F-415L. I believe this is per the instructions that came with the vent. Functions very well. I donít have a vent on the right side.

Pat Falley 01-16-2018 11:31 AM

I did what Bill E describes, it works great. It was an inexpensive and easy weekend project on an already flying airplane.

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