How to Make a Fixed-Wing UAV Fly Vertically

by Graham Warwick
Apr 24, 2014
Long term, vertical take-off and landing (VTOL) is probably the way to go for unmanned aircraft. Get rid of the launcher and runway or recovery system for ease of operation and flexibility. Take off and land anywhere, hover or perch and stare. The disadvantage is that VTOL UAVs can't carry as much or fly for as long as equivalent fixed-wing air vehicles.

Arcturus UAV has come up with a neat way to combine rotary-wing and fixed-wing attributes and pay only a modest penalty. Working with Latitude Engineering, the company has added a quadrotor VTOL capability to its small tactical UAVs, the T-15 and T-20. The batteries, electric motors and rotors are self-contained in two booms mounted under the wing.

Video and photos: Arcturus UAV

The penalties of added weight and drag are minimized by lightening the airframe, which no longer needs to withstand the stresses of catapult launch and belly landing or net recovery, and feathering the rotors longitudinally in forward flight. Endurance is reduced, from 10-12 hours for the  T-15/20 to 6-8 hours for the VTOL JUMP-15/20, but flexibility is increased, argues Arcturus.

Also, while the VTOL air vehicle is more expensive, the overall system is cheaper, the company says, because the launch and recovery systems are not required. Arcturus says it is ready to take orders and has interest from international customers.

The video shows an electric-powered UAV, but in the gasoiline-fueled JUMP-15/20, the aircraft would take off from a small platform so that the engine is running and propeller turning before lift-off. The main engine is then used for station-keeping during the climb to transition altitude. Transition is achieved by throttling up the propuslion engine till the UAV is in wingborne flight, then shutting down the rotors.

To recover, the UAV slows to above the stall and the rotors are started. Latitude's VTOL control software in the Cloud Cap Piccolo autopilot then guides to aircraft to a vertical landing by varying individual motor speed for flight control.

Next up? A smaller version of the JUMP, the ability to recharge the batteries in flight and - maybe, one day - making those booms removable so you can switch between long-endurance rail-launched and flexible VTOL mode.

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