Unmanned Systems Technology 004 | Delair-Tech DT18 | Autopilots | Rotron RT600 | Unmanned surface vehicles | AMRC | Motion control | Batteries

51 Rotron RT600 UAV rotary engine | Dossier Performance Running on 95 octane unleaded fuel in LCR form, the RT600 produces 60 bhp at 7500 rpm. That figure rises to 110 bhp in XE trim at the same peak power speed. The single-rotor equivalent, the RT300, produces 30 bhp in LCR guise, rising to 55 bhp in XE trim. Those figures reflect the dependability and life requirements of aero engine applications; for race engine applications, Cardozo says 80 bhp per rotor can be achieved. Idle speed is 2000 rpm. Power is in the 4500-7500 rpm region. Both the LCR and the XE are tuned for peak power at 7500 rpm, where the redline is set. Peak torque is tuned for 6500 rpm, where the engine will run continuously in most aviation applications, peaking at 7500 rpm for ‘climb and dash’ requirements. Ignition timing at maximum power is in the 17-20 º BTDC range – “unlike a two-stroke, within that range it isn’t very sensitive”, notes Cardozo. A naturally aspirated small-displacement rotary engine accelerates very quickly, and throttle response is described by Cardozo as “rapid”. According to detail engine specification, (unleaded) fuel consumption on the dyno is measured in the 320-300 g/kW/h range at 6500 rpm continuous operating speed. Future development Current development revolves around further extending servicing intervals. Ongoing seal development plus the use of ceramic apex seals is anticipated to increase engine life to 500 hours. Direct injection has been evaluated but not found to be beneficial owing to the movement of the charge in the chamber associated with the motion of the rotor. In the case of a reciprocating engine the situation is far more controlled. Fuel is often injected into a bowl formed in the piston crown, which in turn is aligned with the spark plug through the final stages of compression and then ignition. The situation isn’t that straightforward in the rotary combustion chamber, as it is far more difficult to keep a rich mixture around the spark plug. Since the Everest adventure, there has been a supercharged Rotron single-rotor engine, using Rotrex technology, but so far that has been a one-off. Cardozo says that currently under investigation is a twin-rotor version, but that to date there hasn’t been a request for turbocharging. Doubtless that will come though as new and varied applications extend the reach of Rotron’s new-generation rotary engine. Unmanned Systems Technology | Autumn 2015 Rotor manufacture at Rotron Computer-aided design at Rotron