Unmanned Systems Technology 008 | Alti Transition UAS | Ground control systems | Xponential 2016 report | Insitu Orbital N20 | UAVs | Solar power | Oceanology International 2016 report

69 Insitu N20 UAV 50 cc two-stroke single | Dossier the oil metering pump. It incorporates logging of key engine parameters, and all sensors have redundancy. The ECU has what is described by Cathcart as “advanced diagnostics”. The ECU stores all engine data, while selected information is transmitted to the operator in real time. A diagnostic port allows data to be downloaded directly from the ECU when the craft is parked. Data from all operations is logged, with software run on the operator’s PC automatically able to recalculate the life of individual components in the light of ongoing operation and providing diagnostic information. Thus can the operator carry out their own checks and any required field maintenance. The only routine between- service replacement items are the air filter and the spark plug, and both are accessible by removing the cowl. Extending the time between overhauls was a key target, to minimise the need for field maintenance. “A lot of incidents are post-field maintenance,” notes Beloy. “Through robust design we have minimised the in-field maintenance requirement – even our muffler is maintenance-free.” The N20 in operation The N20 project began in mid-2012, and Orbital’s UAV engine division – Orbital UAVE – started design work in July 2013, just after being awarded the contract. At the start of the project Orbital used rapid prototyping to create representative engines to investigate aspects such as bore and stroke possibilities; this validated its simulation work. The first proper prototype was assembled in time for bench testing at Insitu in June 2014. The engine was certified as flightworthy in January 2015, and was first flown in April 2015. The final prototypes – production-representative engines – were built at Orbital in December 2015. By the end of 2015 the development programme had used dozens of engines, and there had been over 7000 hours of test running. Orbital had run numerous durability tests, matching FAA requirements for manned aircraft engines, and the N20 had come through with flying colours. The aim is to be prepared to certify it for aviation use should the FAA’s remit be expanded to include engines for unmanned aircraft, which is anticipated in 2017. “This could be the first engine certified for unmanned use,” says Beloy. “Already we have achieved our durability target – now we will see how far we can go,” he adds. “In the past we have seen detonation in a conventional spark ignited jet fuelled two-stroke but not in this engine, even when we have pushed to try to induce it.” The N20 runs from 3000 to 6500 rpm and is rated at 2.4 kW at 6500 rpm take- off power. It cruises in the 3500-6500 rpm range and can operate from -30 C to +49 C and at altitudes up to 20,000 ft. Thanks to its innovative design around Orbital’s unique FlexDI technology, it promises to set a new benchmark for engines of its type. Unmanned Systems Technology | June/July 2016 An external starter is used to fire up an N20 on a test rig Assembly of an N20 at Orbital