Airspeed Calibration on the Ground using Aircraft Test Set

We’re using the standard 4525 pressure differential airspeed sensor connnected to a Cube Orange howveer we’re calibrating using an aircraft test set connected to the pitot static lines which essentially supply the pressure differential.

We had two issues:

  1. To caveat the first one, the lines were tested and did not leak (as the aircraft test set did not lose pressure), similalry the airspeed was constant (at least a constant average) however we needed to set a NEW ARSPD_RATIO =12.0 due to the difference between the test set air speed and the mission planner airspeed. I read the literature and it suggest that anythgin greater than 3 was bad however, the pitot tube was not experiencing any unsavory aerodynamic effects from the aircraft (as the aircraft wasn’t flying).
    I’m just wondering if there’s something I’m missing here.

  2. The airspeed sensor output appeared to be extremely noisy. The average seemed ok however, the fluctuations were sometimes +10 / -20 knots down at an average avlue of 25knots and around +/-10 up at 80knots. These weren’t as frequent as the +/- 5 knot variances however were still present.
    I’m just wondering if anyone has experienced this with these sensors or with the way Mission Planner uses the EKF to display the airspeed (is there mixing of another number that skews results) or if there’s something we’re intoducing by doing this calibration method?

Thanks in advance.

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