Unmanned Systems Technology 002 | Scion SA-400 | Commercial UAV Show report | Vision sensors | Danielson Trident I Security and safety systems | MIRA MACE | Additive manufacturing | Marine UUVs

54 Dossier | Danielson Aircraft Systems Trident 100 TD2 turbodiesel The vertical valves are each operated by its respective cam via an inverted bucket tappet. The camshaft and the inverted bucket tappets are DLC coated, and the journals of the DLC-coated camshaft run directly in the cylinder head. The camshaft is chain driven (with cam timing fixed). The drive coming from the front of the camshaft sees the injection pump- operating cams set between cylinders one and two, between cylinders two and three and outrigged beyond cylinder three. A tenth cam provides the drive for a feed pump, which lifts fuel from the tank (through a single line) and delivers it (via an upstream tri-branch) to the individual pumps. Given the pressure and heat of combustion associated with this CI engine, like most turbodiesels it uses oil gallery pistons. That is a step beyond the normal high-performance SI solution of one or more oil jets cooling the underside of the piston. In this case, two jets are arranged to spray through ports feeding a circular gallery that runs within the piston crown. The flow of cooling lubricant escapes through outlet ports, due to the so-called ‘cocktail shaker’ effect. The 100 TD2 is both oil- and water- cooled, with conventional water jacketing for the cylinders. Hubschwerlen remarks that specific attention has been paid to minimising the aerodynamic drag caused by heat rejection. The oil pump is of the gear type and is produced in-house, and contains one pressure and two scavenge stages in the same housing. The water pump is of the centrifugal type and is likewise produced in-house. Transmission The gearbox reduces crankshaft speed to propeller speed at a fixed ratio of 1.28:1, so that at 3600 rpm engine speed the propeller runs at about 2800 rpm. To save weight the engine has no flywheel, and in any case the propeller acts as such. However, there is that feature described by Hubschwerlen as “an innovative torque-smoothing system” located between the crankshaft and the fixed-ratio gearbox. “Due to the running pattern of a three-cylinder CI engine there is a danger of breaking gears,” he explains. This system overcomes the rotational irregularity – acyclism – associated with this type of CI I3: acyclic impulses can cause damage and excessive wear of the transmission gears. The use of the torque- smoothing device allows the use of lighter gears, helping to counteract its weight. “This device stores energy during each combustion stroke and gives it back during the compression stroke, providing a very smooth drive to the propeller,” Hubschwerlen says. “It isn’t a damper, it doesn’t lose any energy, it takes energy and gives it back at the right time to smooth the drive. It is all-mechanical and simple – it has only five moving parts. I Spring 2015 | Unmanned Systems Technology The Danielson Trident 100 TD2 uses a novel ‘torque smoothing system’ Starter-generator for the Trident 100 TD2