Unmanned Systems Technology 017 | AAC HAMR UAV | Autopilots | Airborne surveillance | Primoco 500 two-stroke | Faro ScanBot UGV | Transponders | Intergeo, CUAV Expo and CUAV Show reports

61 Primoco 500 four-cylinder, 500 cc two-stroke | Dossier Unmanned Systems Technology | December/January 2018 The starter gear bolts to a flange formed with the inner section. The starter motor is then mounted above the crankcase, ahead of the generator (to which it has no connection). The crankcase has the necessary mounts for the starter integral to it. The vertical rear engine mounting plate is shaped to accommodate the rear belt drive for the generator within its thickness. The generator drive pulley is attached to the rear of crankshaft with a key to drive it. The rear mounting plate also accommodates a magnetic crankshaft speed sensor on each side (the engine having two for redundancy) which work in conjunction with a trigger wheel that runs behind the belt drive, again within the thickness of the plate. The plate is machined from a billet of 7075 T651 aluminium alloy, and eight M8 bolts are used to attach it to the back of the crankcase. Each of the twin reed housings is machined from a billet of 7075 T651 alloy. This housing and a short inlet manifold immediately underneath the carburettor sandwich the reed itself, and four bolts run from the plate into the crankcase to secure the assembly. The carburettor is sandwiched between a top plate that carries its air filter and adapter plate. Two bolts run from the top plate, through the carburettor body to attach it to its plate. The ignition operates two 10 mm spark plugs of Pt-Ir spec per cylinder. There are four ignition boxes, with ignition timing set by an ECU responding to crankshaft speed, and ambient temperature and pressure. The exhaust has an independent exit for each bank. Four bolts attach each primary exhaust flange to the respective barrel. The fuel tank in the One 150 UAV is a Kevlar production that houses the electric fuel pump. The fuel pump’s pick-up within the tank takes the form of a rotating basket to ensure it maintains orientation as the aircraft moves in pitch, roll and yaw. The tank itself has baffles to stop fuel moving about, which can upset the aircraft’s stability. An electric pump draws from the tank pick-up and sends pressurised fuel through a line to the engine where the two underslung carburettors are fed from a single rail, at the end of which is a pressure regulator and return line. The regulator can be set at anything from 0.05 to 0.35 bar of boost pressure. The bore spacing is 128 mm. The bank offset is 25 mm. Overall length, width and height are 432, 436 and 500 mm respectively. The Primoco 500 takes about 30 man-hours to strip and rebuild for a full overhaul. Some key suppliers: Main structure: in-house Bore coating: Cylinder Line Crankshaft: in-house Pistons: undisclosed, finished in-house Con rods: undisclosed Big-end and main bearings: SKF/FAG Seals: SKF Fasteners: Fabory Fasteners: Wurth Carburettor: Walbro Ignition system: Denso or Bosch Spark plugs: Denso Engine management: in-house Generator: Denso Sensors: Bosch Exhaust: in-house Air filter: K&N Electrical connectors and wiring looms: Teneo Ignition cables: Tesla CZ Fuel pump: Bosch