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Static port location

Posted: Wed Sep 28, 2016 12:26 pm
by jchisolm
CT tail express
I'm not using a Piper style blade pitot/static so I need a separate static port. Any suggestions on where to locate the static port?
I read a post in the old forum where they put it a few inches forward of the sta 162 bulk head (I think it is) and had issues.

Still working on CT when I can

Re: Static port location

Posted: Wed Oct 12, 2016 11:42 am
by jkturner
I recently upgraded my panel to include and all glass panel Skyview setup. I added 2 static ports behind the rear cabin bulkhead about 18". I have had no problems at all with this location. I can provide pictures if you would like.

Re: Static port location

Posted: Fri Oct 14, 2016 3:53 pm
by jkturner
I recently upgraded my panel to all glass (Dynon Skyview) in my Express CT (N360EZ) and needed to add static ports because I would no longer be able to make use of the static port that was in the old pitot tube. I added to 2 new aluminum static ports that I purchased from AC Spruce. I put them on both sides of the fuselage behind the rear bulkhead access panel. I have had no issues with the system since making this change, all has worked out very well. Let me know if you would like pics and I would be glad to take some for you showing the installation.

Jeff Turner

Re: Static port location

Posted: Mon Nov 07, 2016 4:36 pm
by jeffreyhowell
Mine is located about 8 inches aft of the firewall and about 2/3 of the way up from the lower surface OML. I do not know how accurate it is going to be but static ports are easy to calibrate. In past experiences I have used a thin piece aluminum (to create a step) in front of the port or behind the port. The thickness of the step will influence your calibration. One other thing I have done is to buy a static port from AS and machine a step in it just behind the hole and then I clock the port when I screw it on so that I get an accurate reading.

Re: Static port location

Posted: Tue Nov 08, 2016 11:13 pm
by jchisolm
Thanks for the info. I've read elsewhere about doing a step like that.

Re: Static port location

Posted: Tue Mar 28, 2017 9:16 pm
by n49ex
I did have a pitot mast which included the static ports, and found that after adding the G3X Touch autopilot, the AP hunted vertically. evidently the pitot integrated static ports deliver slightly varying pressure with changes in AOA, not noticeable on the altimeter, but causing AP instability. As a result I have engaged in a massive effort to locate the best place for fuselage ports, starting out with a location about 18 inches back from the 162 bulkhead, and while the AP is stable, found the altitude and airspeed off. I've come up with a method of experimentally locating the optimum spot, without drilling numerous holes, and am in the process of writing a Kitplanes article on it. I think it turns out that relatively few homebuilders really know how accurate their airspeed and altitude are, or the laborious processes by which static ports are located on certified product. In any case, for the purpose of Express owners, I have determined that the best location (at least on my plane) is just ahead of the 162 bulkhead, which unfortunately for me is in the baggage door. Fortunately, locating the ports just behind the bulkhead is nearly as good - within 1 mph and 10 feet altitude, so that is what I have chosen as an acceptable compromise. I am using Cleveland Tool aluminum ports.

Incidentally, contrary to the beliefs of some others, I have found the addition of a step ahead of or behind the port hole as a compensation/correction mechanism to not be very effective except for small corrections. That is to say that if your ports are say, greater than 6" from the neutral pressure transition line, a step will not be able to adequately correct it. A 0.060" step will deliver only about a 20ft altitude correction, while altitude error is in the neighborhood of 6 to 7 feet per inch of lateral displacement in the neutral pressure area of the Express. Furthermore, with a step, the correction may not be compensating correctly over a range of speeds, as the boundary layer thickness changes.

Food for thought!

Reinhard Metz