Hybrid VTOL UAVs - Back to the Future

We have a choice of musical styles for you today - and a choice of vertical take and landing unmanned rotorcraft that also fly in fixed-wing mode.

First up is the Aerovel Flexrotor, designed by the same folks who brought you the Insitu ScanEagle. The compnay has just completed what it believes are the first autonomous launches and recoveries of an unmanned aircraft from an unmanned boat. With a 9.8ft span, the 44lb Flexrotor is designed to fly for more than 40hr, or 2,000nm, at speeds up to 79kt, with an imaging turret in its non-rotating nose.


Video: Aerovel

The Flexrotor is a taillsiter (more correctly a wingsitter if you watch the video) that takes off vertically like a helicopter then transitions from rotor-borne to wing-borne flight, which gives it long endurance, before transitioning back to thrust-borne flight for a vertical landing. The slow-turning proprotor provides both vertical and forward thrust. Proprotor cyclic pitch and small stowable roll thrusters at the wing tips provide control in vertical flight, while conventional aerodynamic surfaces on the wing and fold-out tail provide control in forward flight.

The video shows how the UAV, supported by a pair of extending arms, launches itself from the remotely controlled skiff, transitions from vertical to horizontal flight and back again, landing vertically back on to the support arms, which have "combs" to capture the wing. The UAV is then centered and pulled in to be autonomously refueled and restarted for a second launch and recovery cycle. Aerovel is aiming the Flexrotor at civil applications such as geological survey, weather reconnaissance, fishery surveillance and environmental monitoring.


Flexrotor (Photo: Aerovel)

Next up, from Aerie in Austria, we have a modern re-interpretation of the Triebfluegel (thrust-wing) - an unmanned aircraft in which the wing spins like a rotor for vertical flight then stops for forward flight. Aerie says its designs can reach 24hr endurance, three times that of a conventional VTOL design. The video shows the company's progress over the last three years of tests - both rotary-wing and fixed-wing flights and transitions between the two.


Video: Aerie

The aircraft is a "nosesitter" - it takes off and climbs vertically, tail-first, in rotor-borne mode, then dives to convert to forward-flying wing-borne flight. To land the UAV climbs, flips over, and descends nose-first in rotor-borne flight. The big "tails" on which the UAV sits (which become forward-swept canards in forward flight) use downwash from the rotor/wing to counter any torque on the fuselage.

Aerie is working on a range of UAV sizes from 2-200kg (roughly 4.5-450lb). In the 25kg S-25 Swift and 150kg D-150 Dipterion designs, the rotor/wing is driven by two small propellers on the leading edges. The 2kg I-2 ILE has the drive props mounted on seperate stub wings at 90deg to the rotor/wing. while the 200kg K-200 Kestrel has a jet-drive system. Aerie is now taking options on the I-2 and S-25.


K-200 Kestrel (Concept: Aerie)

So there you have it - take your choice: Aerovel or Aerie, tailsitter or treibfluegel, classical or electronic music.