RV Louver from Avery

[Hubitom1]

I know I've seen it somewhere, but can't remember where. Here it goes....

I was looking through Avery today and stumbled across the lover they have for the RV's. I know that they are for additional venting, but did anyone here install them on the outside of the NACA vents on the side of the aircraft that let's fresh air in? The reason why I'm considering this is my fear of water getting into cabin when flying in rain.

Did anyone d this, and what is your experience. I am fairly certain that it will deflect water, but also provide for probably less fresh air coming in. Any thoughts?

Thanks,

Thomas

[Mike S]

They will cause a low pressure there, and suck cabin air out the NACA duct.

[Hubitom1]

... I totally forgot about the siphon effect. You definitely got a point there, Steve. Thanks!

Thomas

[Barry_Barry]

Originally Posted by Mike S

They will cause a low pressure there, and suck cabin air out the NACA duct.

[size="3"]
Mike:

It depends which direction you install the louvers.
BUT! The NACA scoop is probably the most efficient scoop there is so, why would one place louvers over the scoop?

If one is looking for additional cooling - yes, the RV cowl needs a bit of help. The basic rule on intake Vs exhaust is: The exhaust must have twice the area as the intake. And when figuring this start with the overall dimensions BUT! Remember things like exhaust pipes and pipe supports cut down on the area. Also, it does not take much of a cowl flap/exhaust flap to create a negative pressure area right at the exhaust port.

It is quite a challenge to make a good seal on the upper baffle to the cowl top. Lots of curves to try to fit - Rough finish to the inside of the cowl. And very tight and small radius to get to fit. I would go with a Plenum as my first, second and third choice. Then if you really thing you could finish building sooner with a good seal [laughing here] go for the baffle & rubber seal. AND - AND , if you do have good cooling with the rubber seal... Just think how much better it would be with a plenum!

Barry