Dynon Static Port installation

[swpilot3]

Hello,

I bought the Dynon AOA, Pitot, Static Plumbing Kit. In the directions it says the static port should be mounted proud of the aircraft skin. I'm not exactly sure what proud of means. I would think that means the entire static port should be mounted on the outside of the skin.

Then it goes on to say "Drill a 1[ch8260]2” diameter hole (12 mm) from which the port will protrude". A 1/2" hole would seam to indicate that it will be mounted on the inside of the skin with just the small 1/2" port protruding.

Maybe I can't see the forest for the trees here, but I'm looking for some confirmation on exactly how the static port is intended to be mounted.

In my case, it will be mounted to a fabric fuselage.

Thanks!

 

[60av8tor]

Yes, mounted inside with the inner portion protruding (or proud) from the skin ever so slightly. I believe these are the Safe Air ports, or similar. I recently mounted the Safe Air ports in my RV-10 and they protrude just a slight amount - 1/16ish if memory serves.

 

[dynonsupport]

As Jon says, "proud" means sticking out from the aircraft skin, but only the 1/2" diameter part needs to do this, and only minimally. They are designed to work when somewhat out of the boundary layer of the airframe, and sometimes someone will go through a bunch of work to make them super flush, assuming this is better, but it actually causes static error.

 

[n456ts]

Example:

 

[60av8tor]

Example:

Not quite the ports he is talking about.  This is how the SafeAir ports will look:

 

[n456ts]

Exact same concept.  I'm not sure why you think it's different. A static port should be proud of the surface. I provided a real world example.

 

[swatson999]

Exact same concept.  I'm not sure why you think it's different.  A static port should be proud of the surface.  I provided a real world example. 

So now to a more fundamental question that I've never understand the answer to...WHY does the port need to be proud of the surface? Wouldn't that put it into (or near) the free stream, which means that it would be subject to our friend Bernoulli, and thus measure a lower pressure than a point distance from the aircraft?

I've never understood this...can someone explain why the port should not be flush, and thus (as far as I can figure eout) detecting the pressure within or below the boundary layer?

 

[60av8tor]

Exact same concept.  I'm not sure why you think it's different.  A static port should be proud of the surface.  I provided a real world example. 

My apologies. I guess I mistakenly thought your picture was of a Cessna style port which is mounted to the exterior of the fuselage/empennage, which is quite a bit different than an interior mounted Dynon style where only the center portion of the port protrudes from the skin with the rest of the port internally mounted. I took that to be the confusion of the OP.