Fixed-wing drones – airplanes

Airplanes are considered by many as the Holy Grail of UAVs. They can generally fly for a lot longer than multicopters (as they have wings and don't have to use up battery power on lift). They are much easier to fly (as they can actually glide and, if the motor cuts out, they don't drop like a rock). However, the difficulty with airplanes is takeoff and landing.

Since airplanes don't hover, they must be moving at speed to take off and land. Landing an airplane isn't too easy either. They must touch the ground softly, or they may bounce up again, stall, and crash. So, how do you design a drone to land at speed softly? It's not easy. But Pixhawk has been known to do this pretty well.

Also, since an airplane needs to maintain a certain speed in the air to keep wind flowing over the wings in order to provide lift (called air speed); the guidance system needs to know how fast it's moving through the air (not just in relation to the ground). In addition to all of the sensors employed by the Pixhawk for a multicopter; one more sensor is needed for an airplane a pitot tube.

You'll find a pitot tube on any real airplane to measure airspeed. This device is the little sticks you see protruding from the sides or nose of the airplane. The following image shows how a pitot tube works:

Image courtesy of Wikimedia commons

The following image shows a pitot tube on a piloted aircraft:

The Pixhawk does not have this sensor, but one can be purchased to use with it.

Fixed-wing drones can also be launched in a variety of ways. Some are thrown; others are launched on catapult systems, while still others are launched by taking off like traditional aircraft (rolling takeoff with wheels).

The following image shows one of my drones (2012) being launched via a catapult system known as a Jetapult:

Since this drone had a seven-foot wingspan, it was far too large to launch by throwing it. The system was very simple. It used PVC pipe to angle the aircraft and slide it up at a slight angle while a bungie cord pulled the aircraft forward at a high rate of acceleration. If you look closely, you can see the black bungie cord wadded up on the ground just behind the (now flying) drone. The release was a simple foot-pedal that slid a ring off a peg.

Although this is a simple mechanism, even military drones are sometimes launched from catapults (as shown in the following image):