Aircraft Maintenance Technology

APR 2017

The aircraft maintenance professional's source for technological advancements, maintenance alerts, news, articles, events, and careers

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GENER AL AVIATION 18 APRIL 2017 AIRCRAFT MAINTENANCE TECHNOLOGY for several decades on the development of rotary piston engines, even at Fichtel & Sachs. Having invested much in the devel- opment process and having disposal cutting edge machines capable of production of tight-tolerances components, Geiger is confident it will overcome the problems typical to Wankel engines in the past. Two new Wankel engines presented by Geiger in 2016 are the single rotor A1-37 and a two-rotor A2-74. At Geiger the 1, 2, and 4 stand for number of rotors (rotating pistons) and the following number 37, 74, and 150 stand for the engine maximum power in kw. The A2/100-hp weighs dry — with a heavier planetary gearbox 121 pounds (55 kg) and wet approximately 132 pounds (60 kg). DOUBLING THE TWIN, B4 POWERPLANT IS COMING The newest, still to be debuted, engine called B4-150 is Geiger's masterpiece. It consists of two A2, twin piston units — which drive through a clutch, a gearbox with a single output shaft. This uncommon two-engine solution with a single prop or power flange was chosen on purpose to power an aircraft or a helicopter giving the aircraft an unreached redundancy. The weight of the complete 200-hp unit is 352 pounds (160 kg) wet. MODULAR DESIGN All Geiger Wankel engines use the same (rotating) piston and the same epitrochoid-shaped housing/stator, with the resulting unit displacement volume of 305 cc. This unit develops 50 hp at 8,000 rpm. The basic difference is the number of pistons used; that's why the engines are basically the same and just adding a segment, with low weight increase, the output power is being doubled. PROPRIETARY GEARBOXES The planetary gearbox weighing 20 pounds (9 kg) for the A2-100- hp engine was too heavy for the A1-50-hp engine (it would fit on that engine, too) so Alexander Geiger developed a belt-driven unit weighing only 6.6 pounds (3 kg). As all Wankel engines, even this two rotor engine developed full power at high rpm, in this case around 8,000 rpm. MODERN ENGINEERING SOLUTIONS All three engines are equipped with an electronic control unit (ECU) fuel injection and electronic ignition. The fuel injection nozzles are located very close to the engine intake port. We say "port" because there are no valves on Wankel engines — so we can speak almost about a direct fuel injection. Now a single injector solution per rotor is used; the next batch will use two injectors per combustion chamber. DIESEL WANKEL AS A GAME-CHANGER Geiger is now developing versions with a direct (combustion chamber) fuel injection. In this case the engines will be able to run not only with Mogas (ROZ95), but the engines could then also be fueled with diesel or kerosene. This will give Geiger the access to the drones and military market which is going toward single fuel use. In this moment this is a highly confidential matter and engines running on dyno have reached an "almost serial ripeness" according to Geiger. The power output of this spark-plug ignited diesel fuel engine is lower than of gasoline engines but this disadvantage has been considerably lowered. GEIGER RANGE EXTENDER ON THE RISE Geiger debuted at Aero 2017 in Germany a new engine/generator solution for electric aircraft. Geiger is here cooperating with the German generator specialist Engiro. The Geiger/ Engiro 30-kw unit will be a perfect add-on for electrically driven aircraft which can stay airborne for only a limited time on now limited battery capacity. THE IMPROVED DURABILITY The durability of Wankel engines was in the past not really the best. CEO Alexander Geiger is assuring that his engines will be significantly more durable than existing rotary engines. In his opinion better and more accurate manufacturing methods, new materials/coatings, better cooling, and lubrication are guaran- THE NEWEST still to be debuted Geiger B4 engine. RANGE EXTENDER is a 50-hp Wankle engine with a 30-kw generator (in green) mounted.

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