Missions at sea can often be hampered by severe weather conditions that are dangerous to aircraft and their crew. Using UAVs is one option, however they are often small, light and affected by extreme weather.
The Airborne Search and Rescue Project (ASARP) project has been working on a prototype UAV that can remain stable in difficult conditions by using aeroservoelastic trim tabs that vibrate in counterphase to wind gusts.
‘The aeroelastic control surfaces have specially built electromagnetic actuators and electronics to counteract extreme gusts and turbulence,’ explained project coordinator Michael Amprikidis. ‘This is done by rapidly moving the ailerons in the exact frequency of the air-mass wave.’
Accelerometers onboard pick up the start of the gust and, in real time, the control surfaces deflect in the opposite direction to counteract the turbulence, while a controller takes into account the change of airspeed and weight of the aircraft.
The UAV can take off and land on the sea as well as land, and can fly for 4.5 hours carrying a payload of up to 40kg. Its fuselage and wings are made of carbon-reinforced glass fibre and Kevlar composites.
‘We’re also investigating morphing of the wing and automatic changes in the wing span of the UAV depending on the flight phase,’ said Amprikidis.‘This is done in order to enhance the aircraft response in severe turbulence, but also to manage fuel more efficiently.’
A prototype is currently undergoing final trials in Cyprus and, according to Amprikidis, the design is already attracting interest from governmental and civil rescue organisations.
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