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

47 its wall acts as a barrier between the charge passing within the rotor and the combustion chambers. While the LCR version uses its charge air for rotor cooling purposes at the expense of flow restriction and higher charge intake temperature, the XE version is inherently more powerful since it uses a separate air cooling system. The LCR version gains in terms of simplicity, and according to Cardozo still proves superior to current aviation two-strokes in terms of power-to-weight ratio and its compact size. The XE version, reports Cardozo, “uses Rotron’s exhaust extractor system to generate vacuum energy”. In the case of the XE, cooling air enters each side plate separately from the airflow into the throttle bodies, which are directly connected to the respective intake port. To stop dirt passing through the middle of the rotors, where it could interfere with the bearings, air entering each side plate is filtered. The cooling air finds a common exit through the centre plate, as per the LCR. In this case the common exit links through to the exhaust housing, where the energy of the exhaust is used to create the suction that draws the cooling airflow through the engine. In the XE the charge air is drawn directly into a tuned-length inlet port. Fitted to the upstream end is a servo- operated butterfly throttle and, just below it, a single fuel injector, pointing downwards. The throttle body is then connected to the corresponding intake port via a tuned-length intake tube. Interestingly, the XE’s exhaust-driven rotor cooling airflow system also acts as a silencer. “It is a silencer and exhaust energy extraction system all in one,” notes Cardozo. He adds that exhaust temperature is about 1000 C, sometimes more, “so a stainless steel exhaust system is standard equipment”. Liquid cooling Back in the days of motorcycle rotary race engines, Norton developed the combination of air cooling through the centre of the spinning rotor and water cooling for the rotor housing, around the portion subject to the heat of combustion. However, there was still a question mark over the temperature of the main Unmanned Systems Technology | Autumn 2015 There is not yet a heavy-fuel version of the XE single- and twin-rotor engines. Development of a heavy- fuel engine has so far exploited the charge-warming effect of the LCR intake system as well as a higher injection pressure, at 5 bar. The upshot is a heavy fuel-air charge that enters the engine at about 120 C, regardless of ambient temperature (the atomisation of the fuel assisting rotor cooling). The heavy-fuel version of the LCR single- and twin-rotor engines can run on diesel, Jet A1, JP5 and JP8 fuel, with the mapping adjusted (timing and injection control) according to which is used. Heavy-fuel engines The XE’s exhaust-driven rotor cooling airflow system acts as a silencer – it is a stainless steel silencer and exhaust energy extraction system all in one The RT600’s side plates