Unmanned Systems Technology 016 | Hydromea Vertex AUV | Power management systems | Unmanned Space Vehicles | Continental CD-155 turbodiesel | Swift 020 UAV | ECUs | DSEI 2017 Show report

October/November 2017 | Unmanned Systems Technology 52 Dossier | Continental Motors CD-155 I4 turbodiesel Such was the resource capability that the company had established at its base in the Saxony region of Germany. The 2.0 litre was naturally based on the lessons of the 1.7 litre, and likewise gained global certification. The 1.7 litre engine was used until 2006 when this CD-135 replaced it. The CD-155 variant came into service in 2007. Alas, a few years afterwards, Thielert went into administration. Rather than look for a quick sale of its assets, the administrator saw the potential of its aviation business and kept it running for five years before a suitable buyer came along, in 2013. That buyer was the Aviation Industry Corporation of China (AVIC), a partly state-owned enterprise that is bigger than Airbus. The operation bought by AVIC was renamed Technify Motors, while its products are branded under the label of sister company Continental Motors, since that has a high profile in the aviation field. Continental Motors was founded in the US in 1905, and had been bought by AVIC in 2011. For decades it has been one of the few companies supplying piston engines for aircraft use. Its core products are Avgas-fuelled, air-cooled four- and six-cylinder boxers made in various guises since 1931 to produce anything from 95 to 375 bhp. Currently Technify Motors produces two versions of essentially the same turbodiesel – the CD-135 and the CD- 155. Those designations refer to the output in metric horsepower: 135 PS (133 bhp) and 155 PS (153 bhp). Essentially the CD-155 is the CD-135 remapped for a higher output. Aside from that the CD-155 has a compact oil-to-water heat exchanger attached to its structure, whereas the CD-135 has an external radiator for the engine lubricant. This arrangement implies the use of a larger water radiator, on the face of it negating some of the gain from losing an oil radiator, but having just one radiator inlet provides an aerodynamic gain. Engine structure The base engine was designed for transverse installation in a passenger car, whereas the CD-155 is designed to be mounted longitudinally. The car installation had the cylinders canted rather than upright, and this angle is maintained since the cooling and lubricant systems were designed to suit it. This allows the engine to be fitted as a replacement for a four-cylinder boxer in a light aircraft without the need to modify the cowling, or indeed the airframe. The CD-155 is based on a monobloc that is a low-pressure aluminium sand casting machined in-house. Linerless, it is sent for plasma sprayed metal coating of its bores, which are then honed in-house. Ten main studs attach the head to the monobloc, thus four studs surround each cylinder while head-to-monobloc sealing uses a three-layer metal gasket. The aluminium cylinder head is gravity cast using a permanent mould, with the ports and water jacket formed by sand cores and the finish machining done in-house. Indicative of the structural lightness obtained by Technify, the casting forming the sump pan has a wall thickness of less than 3 mm. The monobloc runs to the depth of the sump (it is also known as a long-skirt block). As it was originally designed for an automotive application, a bedplate was sandwiched between the monobloc and the sump. The bedplate integrated the five main bearing caps and a windage tray separating the crankshaft from the sump (having apertures carefully shaped to allow oil to drain down into the sump pan but deterring it from splashing back up – even under extreme g -forces). On the face of it, having an aluminium bedplate at the base of the CAD diagram with a cross-section through the cylinder head The CD-155’s windage tray