Airspeed

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/BR-0004-03-2T.jpg

APM can use an airspeed sensor (shown above) for better speed control and wind handling. Here's how to hook it up.

Solder three-pin headers into the three holes marked "Pitot Tube" on the IMU shield, and in the three holes on the airspeed sensor board (the pins should stick up on the sensor side of the board. Use a spare female-to-female servo cable to connect them. The pin mappings are shown as follows.

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/pitot.jpg

Here's how to connect it with a female-to-female servo cable:

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4859.JPG

Alternatively, you may want to solder the pins to the bottom of the board for a neater installation. Here's an example in an !EasyStar:

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4879.JPG

And here how it looks seated properly in the plane, with an Xbee wireless telemetry module:

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4880.JPG

Software configuration

You need to enable the airspeed sensor as part of the Mission Planner setup as shown below. You can test that it is working in the CLI by using the "airspeed" command in the "test" menu.

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/airspeed_enable.PNG

Installing the Pitot Tubes

When you place the airspeed sensor in your aircraft, use this pitot tube set. The kit comes with two tubes, one static (tiny holes on the sides, blocked end) and one active (plain tube, not blocked). The two tubes can go side by side. In the case of the !EasyStar, you'll need to push them through the foam in the cockpit so they protrude into the airstream. I put mine pretty far in the nose as shown below, to get the cleanest airflow, but if (when!) I crash I'm going to bend them. You may want to mount yours a bit further back in the nose if you're expecting lots of hard landing. Connect the silicon tubing onto the ends of aluminum tubes inside and twist/push them through the foam until they emerge where you want it.

http://ardupilot.googlecode.com/svn/images/five.jpg

Connect the other end of the tubing to the nipples of the pressure sensor on the expansion board as follows:

• Active tube goes on the top
• Static one goes on the bottom

If you are using APM in an aircraft with the propeller in the nose, the active pitot tube must be mounted out on one wing, at least a foot from the fuselage to be outside the prop flow. The passive one can be anywhere.