Unmanned Systems Technology 020 | Alpha 800 I Additive Manufacturing focus I USVs insight I Pegasus GE70 I GuardBot I AUVSI Xponential 2018 show report I Solar Power focus I CUAV Expo Europe 2018 show report

be increased by 30%, while at the same time making it quieter. Escarpenter says the main sources of noise from the Alpha 800 are the same as those of any helicopter, manned or unmanned, namely the engine and a phenomenon known as blade vortex interaction (BVI). All aerofoils constantly shed vortices from their tips, and those that stream from the tip of a helicopter rotor blade can interact with the following blade and generate the characteristic ‘whop-whop’ BVI sound, which happens most often in descending flight. “The only way to reduce that noise source is to reduce the blade-tip vortex intensity,” Escarpenter says. “To do so, we have two options – design a complex blade geometry with blade tips of variable angle or inclined plane, or reduce the lift generated by each blade, which means increasing the number of blades.” Increasing the rotor diameter but sticking with two blades would be more aerodynamically efficient, but would not make the UAV any quieter and might require other changes, to the tail boom and tail rotor for example. Adding blades will give Alpha the extra lift and MTOW it wants, reduce noise and retain the vehicle’s overall dimensions. One of the new engines is a larger capacity version of the existing Zenoah unit, which during our visit was being stripped, cleaned and reassembled as part of Alpha’s effort to find the best air-to-fuel and fuel-to-oil ratios. That has to be done experimentally, as the manufacturer provides very little information, Escarpenter says. The other new engine is a multi- fuel rotary from Advanced Innovative Engineering, a $15,000 power plant intended for applications such as aboard naval vessels, where its heavy-fuel capability will be essential. For landing on moving platforms, Escarpenter explains, the positions of the craft and the landing platform relative to each other have to be measured. For that, the plan is to use GPS with GPS heading and an IMU on the landing platform, with GPS RTK, GPS heading and possibly a laser altimeter or a sonar to measure the vehicle’s height above the platform. Alpha is also considering a vision- based system as a back-up. To develop and extensively test this capability, the company is building a UGV with a three-degrees-of-freedom Stewart platform on its top for the helicopter to land on. Company principal Eric Freeman has financed the Alpha 800’s development along with friends and family, adding that sales revenue has helped reduce the need for external investment. However, he plans to raise venture funding later this year to finance the above developments and build an international sales and distribution channel.