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Static port location

FinnFlyer

Well Known Member
When I got my RV-4 project the static ports were already installed. I assumed with Van's supplied pull rivets. Rivet head outside diameter 3/8". Does that sound like Van's supplied rivets?

Drawing calls for 18" forward of horz stab leading edge and centered on fuselage. Mine are 21" and only 4" above side skin edge.

Reason I'm asking is that I noticed that altitude jumps 20' with engine running. (Yes, I do tap on the altimeter when setting altitude before starting engine.)

I'm not a fan of doing low passes or I would have done that to see if change of airspeed changes altitude readings.

I've read about building a dam before the rivet opening or filing the rivet flat, but am wondering if that's something that will only work with Van's recommended location.

Finn
 
A couple things to try

Since they are already there, I would try a couple things before re-locating them. I assume you have one on each side and they are connected by a tube internally, as they should be. Have you tried masking tape over one and then do the engine run? Perhaps you have blockage creating an odd scenario. Also, while flying level, induce slip each direction. A "low pass" can be simulated with a hard deck at any altitude, so if need to check that block give that a try. My static ports are in the location per DWG, but I made an internal adapter to my aluminum static plumbing that is flush riveted and simply have the small hole in the skin. You may need to install a drilled flush fastener in the location you have and try that. If your static line is "open" to the inside somewhere, and you have vents open in the cockpit, that could change things too. I have zero altitude changes with any odd attitudes or speeds...as it should be.
 
Since they are already there, I would try a couple things before re-locating them. I assume you have one on each side and they are connected by a tube internally, as they should be. Have you tried masking tape over one and then do the engine run? Perhaps you have blockage creating an odd scenario. Also, while flying level, induce slip each direction. A "low pass" can be simulated with a hard deck at any altitude, so if need to check that block give that a try. My static ports are in the location per DWG, but I made an internal adapter to my aluminum static plumbing that is flush riveted and simply have the small hole in the skin. You may need to install a drilled flush fastener in the location you have and try that. If your static line is "open" to the inside somewhere, and you have vents open in the cockpit, that could change things too. I have zero altitude changes with any odd attitudes or speeds...as it should be.

Thanks. I'll try the different things you suggest. But how do you establish the "hard deck" at altitude? Use GPS altitude?

Interesting that your "just a hole in the skin" works. I thought that the rounded rivet head were required.

Finn
 
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