VIDEO: Samarai - Lockheed's Maple-Seed UAV: "Lockheed Martin's Advanced Technology Laboratories is flight-testing a mono-wing rotorcraft, or monocopter, inspired by the maple seed, or samara, and called the Samarai. The aircraft tested earlier this year is a far cry size-wise from the design developed for DARPA's Nano Air Vehicle (NAV) program - that had a wingspan of just 7.5cm, this one is about 30in - but it is being used to develop the flight controls for eventual backpack- or pocket-sized versions that could be launched through a window to fly indoors.
Video: Lockheed Martin
Lockheed was not selected to go forward with the NAV program - DARPA selected a flapping-wing design from AeroVironment - in part because of the challenges in the design, with its monocopter aerodynamics, tip-jet propulsion and rotating-camera guidance, navigation and control (GNC). But the simplicity of the concept compared with other micro and nano UAVs is compelling, and Lockheed has continued to fund research work at ATL.
The 30in-span electrically powered model, several of which were built cheaply using off-the-shelf components, is an easier scale to work with initially, and has enabled development and testing of the flight control system required to operate a monocopter. It has also allowed the propulsion issue to be worked separately from guidance and control.
The next step is a 20-30cm-span 'superscale' prototype, expected to fly towards the end of the year, that will be used for GNC testing, with the goal of demonstrating non-GPS and indoor flight. These vehicles will fly initially with a propeller turning the monowing, but Lockheed says reaction-drive propulsion will be integrated later.
The non-GPS indoor GNC uses the images from fixed cameras on the rotating UAV and the phenomenon of optical flow to provide the data required for flight control. The same cameras provide imagery to the operator. Lockheed is looking at what other sensors, including acoustic, could be added to help with flying and navigating indoors.
Lockheed has a seedling contract from DARPA, called Katana, to study larger applications of the monocopter concept, but the Samarai program is focused on going smaller, down to a few inches for flight indoors, where the monowings simplicity and robustness are seen as having most value."