A lot has happened since we first heard about the AirMule, a prototype VTOL (Vertical Takeoff and Landing) aircraft that features internal rotor blades – these work along with the horizontal-thrust ducted fans visible at the rear. First, it made some tethered autonomous test flights. Then, it flew untethered for a short distance. Now, known as the Cormorant UAV, it's made its first full untethered autonomous flight … although there were a couple of hiccups.

Designed by Israeli firm Tactical Robotics, the Cormorant is designed to deliver troops, civilian passengers or other cargo within tight quarters where helicopters with exposed rotor blades just can't go. With the UAV in its name standing for Unmanned Aerial Vehicle, the idea is that it will perform these tasks either autonomously or by remote control.

The latest test took place in Israel on Nov. 3rd, lasting only about two minutes and involving low flight over uneven terrain. While the aircraft did successfully demonstrate autonomous flight modes such as takeoff, climb, acceleration, cruise, deceleration, descent, turns, hover and touchdown, it is hoped that subsequent flights will be able to smooth out the transitions between those modes.

Additionally, there were points in the flight at which the Cormorant's Flight Management System (FMS) had to override erroneous judgements made by the Flight Control System (FCS).

The FCS basically flies the UAV, utilizing input from onboard sensors such as two laser altimeters, a radar altimeter, inertial sensors, and an electro-optic payload camera. On two occasions, however, ground conditions caused inaccurate laser altimeter readings, making the FCS misjudge the aircraft's height above the ground. On a third occasion, "poor judgement" by the FCS caused the Cormorant to descend too early for its landing.

In all three cases, the FMS determined that FCS' actions were flawed, and overrode them. As Tactical Robotics puts it, "While the FCS was 'learning' to fly the aircraft through the various pattern maneuvers, the FMS was continuously monitoring the level of safety, and making judgements regarding if and when to intervene."

The entire flight can be seen in the video below.

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