Unmanned Systems Technology 007 | UMEX 2016 report | Navya ARMA | Launch & recovery systems | AIE 225CS | AUVs | Electric motors | Lethal autonomous weapons

7 Platform one Researchers from the University of Southampton in the UK have designed membrane wings inspired by bats, paving the way for a new breed of unmanned Micro Air Vehicles (MAVs). The wings use electro-active polymers that work like artificial muscles, changing shape in response to the forces they experience, and have no mechanical parts. The polymers stiffen and relax in response to an applied voltage to change the aerodynamic characteristics in flight. The wings have been developed and successfully tested in-flight on a 50 cm- wide craft that is designed to skim over the sea’s surface and, if necessary, land there safely. “We’ve successfully demonstrated the fundamental feasibility of MAVs incorporating wings that respond to their environment,” said Professor Bharath Ganapathisubramani of the university’s Aerodynamics and Flight Mechanics Group. “We’ve also shown that active wings can dramatically alter the performance. The combined computational and experimental approach that characterised the project is unique in the field of bio-inspired MAV design.” The next step is to incorporate the wings into typical MAV designs, with researchers seeing deployment in real- world applications as being achievable over the next five years.  Bats inspire ‘active’ wings Aerodynamics Unmanned Systems Technology | April/May 2016 Following the US Federal Aviation Administration’s December 2015 ruling that operators of UAVs weighing more than 250 g must register with it, researchers at George Mason University in Virginia analysed a quarter-century of US bird-strike data to produce their own estimate of the risk to commercial aircraft from UAVs of up to 2 kg. They concluded that the risk is minimal and went on to accuse the FAA of conflating UAV sightings reported by pilots with near-miss reports, thereby stoking sensational media headlines. “We estimate that 6.12 x 10 -6 collisions will cause damage to an aircraft for every 100,000 hours of 2 kg UAS flight time”, said Eli Dourado and Samuel Hammond of the university’s Mercatus Center. “To put it another way, one damaging incident will occur no more than every 1.87 million years of 2 kg UAS flight time. “We further estimate that 6.12 x10 -8 collisions that cause an injury or fatality to passengers on board an aircraft will occur every 100,000 hours of 2 kg UAS flight time, or once every 187 million years of operation. This appears to be an acceptable risk to the airspace.” Dourado and Hammond argue that bird strikes provide “an excellent parallel” for the damage a collision with a small UAV might cause an aircraft, pointing out that the US bird population is estimated at 10 billion and that the FAA itself has been keeping track of collisions with them since 1990. The FAA recorded 160,000 “wildlife” strikes between 1990 and 2014, of which 14,314 caused damage. In 80% of these, the damage was caused by medium- sized to large “animals”. On average, it said, only 3% of reported collisions with small birds caused damage, compared with 39% of impacts from large birds. One complicating factor is that bird strike reporting is voluntary, so the true percentage of strikes that cause damage is probably much lower, the researchers argue, because those that don’t are likely to be missed or under-reported. Injuries to people are even rarer, with 100 of the 398 total attributable to one incident, the 2009 US Airways Flight 1549 Hudson River crash caused by geese sucked into both engines. Over the period covered by the statistics, there were 238 incidents involving injuries or fatalities; restricting the analysis to commercial aircraft reduces the total to 37 in 25 years, in which there were around 27,000 commercial flights per day. Overall, only 12 wildlife strikes resulted in fatalities and only one involved a commercial airliner, and none involved a small bird. The researchers found that 20% of collisions with animals weighing about 2 kg will cause damage, with the probability of passenger injury or death being about 0.2 %. Bird-strike risk over-egged Air safety The membrane wings have been proved in this sea-skimming vehicle (Courtesy of the University of Southampton)