I ended up making the air dams out of .063" AL and my ASI at cruise seems to be about dead on. However, since adding the air dam, I have felt that my approaches have been fast, with floating. I did some stalls and my stall speed is about 7-8 MPH faster than during my Phase I. I did some GPS boxes and at 80 MPH, My Indicated is about 4 MPH high. I suspect it is even more at 60 MPH, but haven't tested there yet.
For those of you that have added these dams to increase static pressure, have you found similar results? Maybe the shape of my dam is part of the cause. Here is a picture of mine. It is just taped on until I complete testing.
Larry
The same method, but backwards. The small "air dam" goes in front of the static port hole instead of behind it. This is fairly common in some Cirrus airplanes.My ASI is reading about 5-10kts too low, depending on speed. I have the standard Van's static ports, and a simple stainless steel tube for pitot, in the same shape and size as the plans specify. Both were checked by an A&P to ensure that the instruments are reading correctly, so it is probably due to "installation error".
I have not yet flown with my wheel pants as I have been breaking in the engine, but will install them shortly.
Seems that reading too high is common, reading too low not so much. What's the currently accepted way of correcting this? Thanks!
Seems that reading too high is common, reading too low not so much. What's the currently accepted way of correcting this? Thanks!
I did several 4 course speed runs to confirm my airspeed calibration and found it to be 7 kts lower than the GPS calculations.
I used a standard pulled rivet for the static port and am wondering if I this is correct, can someone please post a photo of the correct style rivet.
Thank you
I had both tested by an A&P along with my transponder - they "passed".Test pitot and static system for a leak.
I had both tested by an A&P along with my transponder - they "passed".
I also used the type of rivet that Paul linked to - the broad head type that is also used on the baffles.
So an air dam in front of the rivet is the trick?
Yes, you are right - he had a different calibrated box for the ASI and Altimeter test - this is required as part of our "certification" process here.Did the inspector also check the pilot circuit for leaks?
Your photo shows a static system test for a transponder certification. Here in the USA, having a transponder certification check done doesn't automatically mean that a pitot leak check is done also.
A leaking pitot circuit will cause a low IAS indication.
If you know for sure that it is leak free then a static pressure adjustment may be needed.
Edit: I just looked up the tester shown in your photo and the specs say nothing about it being able to pressurize and test pitot systems.