# Software configuration

## Software with Mission Planner

You need to enable the airspeed sensor in **Mission Planner | InitialSetup | Optional Hardware | Airspeed**.

![](https://2868710084-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LXNkiDAfBq1Vqjka00H%2F-LXyDwNhnrkfcxeGY5Gv%2F-LXyEDWFGv57BwOtun6U%2Fairspeed-drotek-dropix.jpg?alt=media\&token=020dc8a8-61ea-46c9-8ad1-f5c40c611b23)

> Note:
>
> 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. As a check, you can take the fleshy part of your fingertip and press it against the pitot tube to raise the airspeed reading up to say 15 m/s. It is easy to see that holding a significant constant differential pressure like this the reading does not bounce around (if you keep constant pressure).

![](https://2868710084-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LXNkiDAfBq1Vqjka00H%2F-LXyDwNhnrkfcxeGY5Gv%2F-LXyEVfmibE4wfTEJ84C%2Fairspeed-drotek-dropix-pixhawk.jpg?alt=media\&token=38da595f-dd45-42c0-ad39-ae41b8250f89)

Once you have the airspeed sensor connected, you can use it to control aircraft speed in auto modes. Change the “Cruise” setting in the  Basic Tuning screen of  Mission Planner:

![](https://2868710084-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LXNkiDAfBq1Vqjka00H%2F-LXyDwNhnrkfcxeGY5Gv%2F-LXyEdpUKQGemwuU22PA%2Fairspeed-dropix-700x484.jpg?alt=media\&token=139a471d-0ca8-46d3-9dd9-b9b8f582fae3)
