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While designing pitot/static system, I notice that the Dynon AoA/Pitot probe does not have a static port. Most other probes come with Pitot and static pressures. Is it a common practice to put the static ports at the sides of a fuselage? What are the advantages/disadvantages of the two different approaches ( [Pitot/static in a single probe] vs [Pitot probe + static port at fuselage sides] ) ?
It's fairly common in a lot of commercially built aircraft from single engine trainers to the heavy airliners.Quote:
Is it a common practice to put the static ports at the sides of a fuselage?
The most common problem is placement of the static port in a place where you are getting a "valid" stream. The major advantage of the single port/pitot arrangement is simplicity. Have you asked Dynon if you can use another manufacturer's pitots with their system? That might be an way to get the combined port/pitot system on your aircraft.Quote:
What are the advantages/disadvantages of the two different approaches ( [Pitot/static in a single probe] vs [Pitot probe + static port at fuselage sides] ) ?
Fly Baby's been using a single pitot/static boom for 50 years....
Ron Wanttaja
Locating static ports on the aft fuselage is often a trial and error exercise in practice. You want the location that results in the least system error across the range of airspeeds that the airplane flies. To pick a starting point you can look at where similar designs place the ports.
Alternately, you can add a static boom to complement your pitot boom. If you want, put it on the opposite wing or on the vertical fin's leading edge. A static boom is just a tube with a closed forward end and static ports on the side. You may need a collar just ahead of the ports to create a small area of stagnant air. Take a look at the static ports on the pitot-static booms on the Extra 300 or the Pitts aircraft. Or the static ports on the old recip military aircraft pitot-static booms.
One note if you have an aircraft similar to an RV, the air in front of the wing "sees" it coming out to maybe 12" ahead. So if you are sampling the air ahead of the leading edge, put your ports out that far. If you are picking off the pressure below the wing, take a look at the Piper set up. I think that their static port is 6" or 7" below the wing.
Best of luck,
Wes
N78PS
I do not know how you define "aft fuselage". Most on-fuselage static ports are located in the front section of the fuselage. Remos is one example with static ports next to the firewall.Quote:
Originally Posted by WLIU
I think the reference length for the boom protruding distance is the chord length of the wing. What are the chord lengths for RV and (which) Piper in your example?Quote:
Originally Posted by WLIU
I still have one question: why Dynon did not put Pitot/AoA/Static in one boom? Any speculation？
The Cessna 152, 172 and 182 all have static ports on the side of the fuselage. Given the tens of thousands of those aircraft that have been produced, I would say that it qualifies as "common practice."
Same with the 8000+ RV's flying. They have a static port on each side of the aft fuselage, been this way for thirty years. The ports are located about halfway between the seats and tail surfaces.Quote:
Originally Posted by Bill
On the topic of "why Dynon did not put Pitot/AoA/Static in one boom?", I will speculate as an engineer that trying to get three lines out the back of the probe, all ending in AN flare fittings, created too bulky a package to fit into a hole in the leading edge of the wing, and was too expensive to manufacture. You can only put some much s... into a bag, so to speak.
In addition, if the largest part of the target market is the RV community, those airplanes do not need a static port on the pitot tube.
Hope this helps,
Wes
N78PS