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

54 Dossier | AIE 225CS UAV rotary the heat exchanger is integrated into the rotor housing, deliberately situated on the cold side of the engine. The alternative, depending on application, is to use a remote heat exchanger. “The advantages of Compact SPARCS include having a heat exchanger in the cold side of the engine, which reduces the differential temperature circumferentially around the rotor housing”, remarks Bailey. “That differential is inherent in a rotary engine, having a hot [combustion] side and a cold [intake] side. “With Compact SPARCS you can use a common liquid cooling system for the entire engine.” Bailey adds, “An advantageous fundamental feature of SPARCS is that at higher power, when more heat is being rejected into the rotor, the static pressure of the gas cooling system rises, and thereby with it the cooling capability. By contrast, at lighter loads when less heat is being rejected, April/May 2016 | Unmanned Systems Technology David Garside was made director of engineering at Norton in 1976, and as such he oversaw development of its first rotary- engined motorcycle, the Norton Interpol II. Garside had graduated from Cambridge University with a first-class honours degree in Mechanical Sciences. Early in his career he had worked at Rolls-Royce on a diesel rotary engine project which for various reasons was not pursued beyond the r&d stage. In 1969 he joined the BSA Research Centre specifically to work on its new motorcycle-focused rotary engine project. BSA ran into financial problems but its rotary project continued from 1973 with Norton, which acquired it via a short-term marriage of the two companies. The Interpol II, which had a twin-rotor engine, went into production in 1984. Encouraged and financed by Dennis Poore, the enthusiastic owner of Norton (via Manganese Bronze), Garside was able to start the design and development of a water-cooled rotary in 1981. Initially aimed at motorcycle application, this work subsequently (in 1984) led to the sale by Norton of a licence to Teledyne Continental (USA) for aircraft applications. That sale provided funds for significant further engine development, and the relationship with Teledyne led Norton into the UAV engine business. In 1992, Garside led a management buy-out to acquire from Norton the exclusive rights to use the rotary engine technology and assets for UAV application. A new company, Alvis UAV Engines, was thus created, with Alvis Coventry providing finance for the buy-out. In 1994 though, Alvis Coventry ran into problems and sold its entire shareholding to Silver Arrow, which was subsequently acquired by defence electronics company Elbit. Garside retired in 2001 but continued to keep in touch with the rotary engine via occasional consultancy visits to Elbit in Israel. The SPARCS patent was applied for in 2008, shortly followed by a Compound Expansion System patent (CREEV), and Compact SPARCS in 2011. In 1993, Norton had sold the rotary engine rights for manned aircraft to Mid West, which in turn via acquisition led to the Austro Engines UAV rotary profiled in UST issue 3 (Summer 2015). Meanwhile, Elbit was exploiting the unmanned rights through UK-based UAV Engines. The current managing director of AIE, Nathan Bailey, worked at UAV Engines for a number of years, the first two alongside Garside. Bailey was production manager as the company grew signicantly. Seeking a new challenge, Bailey left UAV Engines in 2010 to work as an independent consultant. Having found a private investor keen to support a new rotary engine company, he formed AIE in May 2012. He initially acquired some non-exclusive rights to Garside’s patents in 2012, and subsequently the full exclusive rights in 2015. Bailey says, “David, with his incomparable accumulated knowhow in Wankel rotary engines that makes him a leading authority in the field, has contributed invaluably over the years at a technical advisory level to our organisation.” These days AIE employs 15 people, with Bailey as managing director, Alexander Vaughn as commercial director, Andrew Turner as senior development engineer and Nazeel Panthakkalakath as senior design engineer. With the creation of AIE in May 2012, the 225CS project described here began in August of that year. The first engine had its initial run during February 2014, on a propeller dyno. It is the Generation Two production unit that is now supplied to customers. Having proven the 225, AIE is now introducing the smaller 40S and the larger 650S, both likewise single-rotor engines. The 40S is just 125 mm tall, weighs 2 kg and produces 5 bhp from its 40 cc, while the 650 cc engine is 331 mm tall, weighs 28 kg and produces 120 bhp. Both engines use external SPARCS, whereas Compact SPARCS, as used by the 225CS, will be a feature of the 125CS and the 650CS models that will follow in due course. Background