Unmanned Systems Technology 027 l Hummingbird XRP l Gimbals l UAVs insight l AUVSI report part 2 l O’Neill Power Systems NorEaster l Kratos Defense ATMA l Performance Monitoring l Kongsberg Maritime Sounder

66 Dossier | O’Neill Power Systems NorEaster from not being able to get the speed and horsepower they wanted (although the engine ran with vibrations as low as they hoped for). “In my opinion, the stroke cycle is irrelevant,” Norton says. “If you can make a two-stroke cycle work on this engine, you’ll get as much power as you would from a crank engine.” Many of the components and much of the ancillary engine systems surrounding the drive and transmission are COTS products, having been selected principally for cost-effectiveness. The main aim of development has been to iterate and optimise that patented transmission across each prototype, rather than develop costly bespoke subsystems to maximise the performance specifications. With the minimal vibration, secure reduction ratio and low maintenance requirements of the drive transmission system – especially when compared with helicopter powertrains – as core selling points, O’Neill Power Systems has made it clear that the various supporting systems are bound to improve in the future. As the company is actively seeking partnerships for the NorEaster’s further development, its engineering team is open to input on what the exact nature and form of those improvements will be. Their own future objectives include an aviation-grade ECU with electronic fuel injection and an improved ignition system. At the moment, O’Neill Power Systems is located at the University of Massachusetts Dartmouth Center of Innovation and Entrepreneurship, where professors and students contribute to the engineering and business development as well as other aspects of the company. Much of the ongoing work on the engine is overseen (and aided) by Edward Spring, laboratory manager and mentor at UoM Dartmouth. Cam drive and transmission The NorEaster weighs 91 kg, with dyno tests thus far indicating a peak power output of 100 hp (75 kW). The system measures 92 x 92 x 30.5 cm, not including the output shafts, which will vary in length depending on the end- user’s vehicle and the flexibility of the rotor material they have selected. Its speed is in the 1000-2000 rpm range. Maximum torque output is 950 Nm, with 760 Nm produced during normal operations and is dependent on the design of the combustion cycle and its components. O’Neill estimates that this degree of power and torque could enable a helicopter UAV incorporating the NorEaster could carry up to 450 kg of payload, making it particularly applicable for aerial logistics, urban air taxis and other heavy-lift missions. The inside of the engine contains two chambers which are symmetrical in the horizontal axis. Each chamber contains one drive cam – a four-lobed arrangement resembling a four-pointed star, designed to be push-actuated by the NorEaster’s pistons. Both output shafts extend upwards through the engine, with the lower chamber’s drive cam’s narrower shaft threading up through the wider shaft mounted on the upper chamber’s cam. Each drive cam is also oriented to rotate in the opposite direction to the other, to provide the counter-rotation of the propellers. The eight cylinders and pistons are oriented radially and co-planarly around the eight external surfaces of the ‘cam case’. Rather than comprising a conventional head and pin to attach a con rod’s small end, the NorEaster’s piston heads have a fixed 5 cm rod extending from underneath them, into the cam case. At the bottom of the central shaft comprising most of the piston rod is a perpendicular cross-member. As the pistons move up and down, their linear motion in the cylinders (and the absence of transverse forces in the cylinder from con rod oscillation) is maintained by keeping the rod cross- members slotted within a guide plate. The cam case contains two of these guide plates – one for the pistons’ upper cross-member halves, another for August/September 2019 | Unmanned Systems Technology The NorEaster is a reciprocating engine that integrates a counter-rotating cam-based drive transmission instead of a conventional crank-con rod arrangement

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