Static system thoughts

[RandyL]

When building an aircraft I've learned that it's not possible to think too far ahead. So I'm thinking ahead regarding my pitot/static system, and in particular about the static system.

There seems to be three options for handling the static system...
1) Vent the back of the pitot/static instruments to the cabin atmosphere.
2) Install static ports on the rear sides of the fuselage
3) Install a combo pitot/static tube such as this...
http://www.aircraftspruce.com/catalo...pitot15144.php

Thoughts on each:
1) Of course the simplest thing is to just vent to the cabin. The problem is that if the cabin pressurizes at all then your airspeed and altitude are off. I despise inaccurate instruments! I know with an RV simply opening or closing a cabin vent will increase/decrease the airspeed 10-20 mph, but then that's a higher airspeed aircraft. Anyone have any experience with this with the Kitfox, and have you ever tried opening/closing vents or doors and observing the effect?
2) Installing ports in a neutral pressure area somewhere on the side of the fuselage, and installing mirror image ports on each side that are tied together and cancel any slip/skid, is the method of choice for certified aircraft, and also in the world of RVs. This requires the designer to do some reasearch and verify where a proper neutral pressure area is on the fuselage. Anyone know where that might be on a late model Kitfox? Then there's the issue of what sort of fitting to use and what the effect of the fitting is on the pressure reading. I know some RV builders have used aftermarket flush static ports instead of the Van's-specified pop-rivet. Those folks later report a 10 knot error, in other words just the 1/16" or so the pop-rivet sticks up into the airflow is needed for an accurate reading, go figure.
3) I've seen these dual function probes on Citabrias and other certified aircraft. This seems like it might be a good solution for a Kitfox, anyone have any experience with them?

Some might way I'm over thinking this, but hey, I like to know my instruments are accurate.

[jonbakerok]

Funny, I don't think I've seen anything in my M4 manual about the pitot-static system. You mean even the late model kits don't give you a hint?

But $17 for that ACS unit settles the issue for me. Now I just have to figure out where to mount it. I had a heated Piper pitot-static mast in my RV6 and loved the simplicity of having it all in one place. It worked fine.

[darinh]

I opted for the port on either side of the fuse. I don't remember the exact measurments but my manual specified the location...it is in front of and below the leading edge of the horizontal stab. I bought the kit from safeair.com and would use it again for sure. So far my instruments have been right on.

[jdmcbean]

Randy,
The tested area is approximately 2" up from the bottom longeron and approximately 24" forward of the horizontal stabilizer.. I can get the actual tested dimensions. The Model IV is located in the same approximate location but is different. We are working on a pitot tube not unlike the one you found in Spruce.

Ironically I have the static port in the tested location and found it to work well in normal flight. However, not in slips or skids... I think having it on both sides is the way to go for better accuracy. I currently have it ported in the cockpit and have run with the doors open.. Unfortunatly, I do not remember the specific changes at the time.. I do not remember it being significant.