Digital Airspeed Sensor with Pitot Tube for Pixhawk

Airspeed sensors are highly recommended for fixed-wing and VTOL frames. They are so important because the autopilot does not have other means to detect stall. For fixed-wing flight it is the airspeed that guarantees lift not ground speed!

This Digital Airspeed sensor is a perfect match for our Pixhawk Flight Controller, giving you telemetry feedback and a more accurate way for the flight controller to determine airspeed, over just relying on GPS calculated ground speed.

This unit has a very high resolution, low offset digital pressure sensor which enables it to register extremely accurate airspeed readings. This sensor does not suffer from noise caused by long cables or from offsets caused by ratio-metric outputs which older analog airspeed systems suffer from. The Measurement Specialities 4525DO sensor is capable of measuring speeds of up to 100m/s (223mph/360kmh) using a 0.84 Pa with data delivered at 14 bits from a 24 bit delta-sigma ADC. This airspeed sensor also has a built-in temperature sensor to allow the calculation of true airspeed from the indicated airspeed using the MS5611 static pressure sensor on the Pixhawk PX4.

Included with the sensor is a differential pressure pitot tube and silicone hose. For accurate airspeed measurements, ensure that the pitot tube is located in clean airflow, well away from propeller wash and exhaust. The airpseed sensor kit connects to the I2C hub on pixhawk 1 and pixhawk 2 boards.  However on pixhawk 2 boards you will need a JST-GH connector as this unit ships with a connector for pixhawk v1 boards only.

Pixhawk Setup Instructions here.

You dont need to use an airpseed sensor if you are flying a multicopter, as its only used with the arduplane fixed wing code.

Useful Tips:

• The kit includes a differential pitot tube that replaces the need for two separate probes. The pitot tube’s inner tube that measures the dynamic pressure, and the outer section measures the static pressure.
• If you are using Plane in an aircraft with the propeller in the nose, the pitot tube must be mounted out on one wing, at least a foot from the fuselage to be outside the prop flow.
• The airspeed sensor reading is automatically zeroed by the APM during initialisation, so it is good practice during windy conditions to place a loose fitting cover over the pitot tube that shields the front hole and the four small side holes from the wind. This cover should be fitted prior to power on and removed before flight.
• You can check the airspeed reading with Mission Planner or another ground station. Just blow on the pitot tube and observe the response. In still air oscillation between zero and small values (2-3) is normal. The airspeed varies with the square root of the pressure, so for differential pressures near zero it varies quite a bit with very small pressure changes, while at flying speeds it takes much greater pressure changes to produce a similar change in speed. If you see mostly 0, 1, 2, with an occasional bounce to 3 or 4, consider it normal. You will not see that sort of variability at flying speeds.