I am in the process of setting up a new airframe and I have a question about the placement and length of the tubing. Since the active is not suppose to be put in the prop wash area, can I put these in my wings and run longer tubing to them and still get accurate results? Or can they only be so long? I have only set up in an easy star before and I am in the process of building a great plane PT-60 and a 6' Telemaster. Thanks for any info on this
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Straight pitot setups are fairly forgiving, but a few notes;
You already know you want to avoid the prop wash.
When putting your pitot out on the wing, the end of the tube needs to be 1/3 chord or so forward of the wing, to avoid the circulation flow due to wing lift.
Unless you have coils of it in there somewhere, the tubing length can be neglected.
On the other hand, leaks will mess up your reading, as will kinks or blockages in the line.
The length of the tube should not make much differance, as long as there are no kinks in it and it does not become hugely long. Try to make it as short as you need it though, ie just outside of prop wash, not on wingtip.
Correct me if i am wrong but I think that the ardupilot code preforms a ground startup calibration, and then only measures the difference in pressure between the pitot, and inside the cockpit to get airspeed, so if there was a difference because of a long tube, it will be constant so you should not get any huge errors compared to a shorter tube and the calibration at startup would cancel out the error
Yes, you can run them out on the wings. A rule of thumb is to put them at least two prop radius (and ideally three) away from the fuselage, to keep them out of prop wash. The silicon tube can be as long as you want, I think.
Replies
I have related question, so I'll ask here.
Can I place both tubes on the side of fuselage, facing towards on a pusher plane?
You already know you want to avoid the prop wash.
When putting your pitot out on the wing, the end of the tube needs to be 1/3 chord or so forward of the wing, to avoid the circulation flow due to wing lift.
Unless you have coils of it in there somewhere, the tubing length can be neglected.
On the other hand, leaks will mess up your reading, as will kinks or blockages in the line.
Correct me if i am wrong but I think that the ardupilot code preforms a ground startup calibration, and then only measures the difference in pressure between the pitot, and inside the cockpit to get airspeed, so if there was a difference because of a long tube, it will be constant so you should not get any huge errors compared to a shorter tube and the calibration at startup would cancel out the error