Introducing AAI's Shadow Knight

Introducing AAI's Shadow Knight: When UAV specialist AAI licensed Carter Aviation Technologies' slowed rotor/compound (SR/C) concept in 2009, it raised a few eyebrows. Tiny Carter had been working on the technology for years and, until then, had failed to secure any mainstream interest.

But AAI believed Jay Carter's reinterpretation of the autogyro offered the promise of an affordable VTOL capability for unmanned aircraft, without the weight, complexity and maintenance burden of a conventional helicopter's powered rotor.

Initially, AAI's focus for SR/C was on adding an unpowered rotor to the RQ-7 Shadow to produce a tactical UAV that, by virtue of VTOL capability, would be independent of both rail launchers and runways. It has also studied a larger cargo UAV using SR/C and uses the technology in its Transformer "flying Humvee" design for DARPA.

Now the company has unveiled the Shadow Knight, its contender for the US Navy's Medium-Range Maritime Unmanned Aerial System (MRMUAS) requirement for a shipboard VTOL UAS significantly more capable than the MQ-8 Fire Scout.


Concept: AAI, via Mike Hirschberg

Shadow Knight uses SR/C technology, but with a twist. Where Carter's design can take off and land vertically by first spinning up the high-inertia rotor, it can't hover. Recognizing that getting on and off a ship will require the ability to hover, AAI plans to add the capability to power the rotor.

That would seem to negate the principal benefit of SR/C - that it's unpowered rotor is simpler and easier to maintain than a conventional helicopter dynamic system. But AAI argues that the clutch and transmission needed to drive the rotor during take-off and landing would have a much lower duty cycle, and maintenance burden, than a helicopter drive system.

In forward flight, Shadow Knight would still fly like a compound autogyro. Props would provide forward thrust, the now-autorotating rotor would be slowed to minimize drag, and lift would transfer to the aerodynamically efficient long-span wing. The result, AAI believes, would be greater speed and endurance than a conventional helicopter.

AAI's data sheet for the Shadow Knight says it would meet the MRMUAS requirement to provide continuous surveillance at 300nm from the ship while carrying an 880lb ISR/strike payload. Dash speed would be up to 230kt and an additional 33 cu ft of payload space would provide a cargo resupply capability.