AUVSI: How To Land A UAV
Writing by Evan Ackerman on Thursday, 13 of August , 2009 at 6:42 am
Launching a small unmanned aircraft is pretty easy… All it takes is a little catapult, a slingshot, or in some cases, just a strong arm. Landing a UAV, on the other hand, is not so easy. Winged aircraft have to maintain a fair amount of forward speed to keep from stalling out and plowing into the ground, and that makes precision landings hard to pull off, especially for UAVs that don’t have room for accessories like landing gear, which is bulky, heavy, and useless for 99% of the time.
As you might expect, a variety of different solutions to the issue of landing UAVs have been put forward, and we saw a few of them in action at AUVSI’s unmanned systems demo earlier this week. The first solution is probably the simplest: a controlled crash. The Aerovironment Puma AE UAV returns to a GPS waypoint near the ground, slows down to a stall, and then pancakes into the ground, breaking into pieces which can be easily reassembled.
If you’d rather have your UAV return in one piece, a parachute is a good option. The Aeronautics Defense Systems Orbiter UAV will return to a specified GPS location, make an orbit or two to test out the wind speed and direction, and then slow to a stall and deploy its own little parachute about 100 feet above the ground, to float down to a safe landing.
Sometimes, UAVs need to be landed in one exact spot with no room for error, as on the deck of a moving ship. In the same way that aircraft carriers use arresting cables to catch landing planes, the ScanEagle stops itself with a cable, except in the vertical plane:
The ScanEagle navigates to the cable with such precision (on the order of two centimeters) that it’s actually able to aim to hit the cable with one of its wing roots, close to a titanium hook that catches the cable on impact. It certainly looks violent, but it’s only about a 12g impact, which is less than the 15g catapult that the ScanEagle launches from. The advantage of this system is that it’s capable of reliable, precision landings in a very small footprint, especially suitable for platforms like moving ships.
It’s worth mentioning that none of these methods are really “best.” Rather, each is well adapted to the particular UAV and the situation that the UAVs find themselves in. As dramatic as the cable capture is, my personal favorite is the controlled crash landing of the Puma. It’s simple, straightforward, a testament to the robustness of the UAV, and since you’d just have to disassemble the thing post-flight anyway, it saves you a bit of effort at the same time.
[ Puma AE ]
[ Orbiter ]
[ ScanEagle ]
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Category: Military
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