Static Port Location

[Gary Wilcox]

Has anyone tried putting the static ports near the NACA vent instead of in the aft of the fuselage? In a plane that will be flown as vfr daytime only, would it make that much difference? For that matter, seeing it is not a pressurized aircraft, why not just have the static port inside the fuselage like an alternate static port is in certified planes? Any thoughts or previous expeiriences welcome.
Gary

 

[Mel]

The pressure inside the fuselage varies greatly, depending on what vents are open. Static sources open to the cockpit will affect your air speed and altitude readouts considerably. One particular manufacturer has cone this on their prototype aircraft advertising a cruise speed of 135mph. Unfortunately builders who properly install a static system find that the airplane only cruises about 100mph.
Static port placement is critical. Van has researched this and determined where they should be. Other people have experimented, but to my knowledge, no one has found a better place.
Mel...DAR

 

[gmcjetpilot]

Per Plans

Has anyone tried putting the static ports near the NACA vent instead of in the aft of the fuselage? In a plane that will be flown as vfr daytime only, would it make that much difference? For that matter, seeing it is not a pressurized aircraft, why not just have the static port inside the fuselage like an alternate static port is in certified planes? Any thoughts or previous experiences welcome.
Gary

What MEL said, Build per plans. The area behind the firewall, where the NACA scoop it is an area of extreme pressure variation. Even attempts to mount outside air temp probes in this location has produced poor results. As Mel said the best place for static pressure is about 50 feet behind the tail.

Suggest you put right where van said and use the pop rivet. Even using those flush aftermarket fittings can produce excessive static error. I bought a few stainless protruding head screws that are machined down to a little bump (like a pop rivet head) and drilled center out; another builder made them up. They are a little more substantial than the pop rivet, while having the same function.

I know Cessna has static ports forward, and it works but not that great. Ever slip a Cessna, the a/s is way off. No doubt Cessna made an aerodynamic and a production cost decision due to easy installation. The dual ports on the RV, aft fuselage, is about as good as it gets. If you want to experiment, some use a piper pitot/static that puts both ports in the same location on the pitot out on the wing.
George