DEC 2014

Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.

Issue link: http://experimenter.epubxp.com/i/434207

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Page 40 of 44

EAA Experimenter 41 liquids for the LF26/39 engines are 137/185 pounds (63/85 kilograms), respectively. CLEAN ENGINE TOP The upper portion of the D -motor engine is unusually "clean" for a liquid-cooled engine. There are only two hoses on the four-cylinder engine and four cooling hoses on the six-cylinder engine that lead to the coolant collector, and the intake and exhaust are located below the engine, which allows for a very flat engine cowling. UNCOMMON FIRING ORDER The firing order of the D -motor engines is different. Nor- mally, the firing order in four-cylinder engines is 1-3-4-2. The four-cylinder D -motor firing order is 3-1-4-2. This sequence was chosen a few years ago because the vibra- tions of the engine featuring the modified firing order was significantly lower than in those with a conventional firing order. Even if this seems to be an easy conversion, in reality it wasn't. D -motor has solved all related problems, and the engine now runs smoothly. PROPRIETARY ECU AND FUEL INJECTION As is common for a modern engine, a computerized en- gine control unit (ECU) is responsible for ignition and fuel injection. This ECU comes from the company called Optimax. A single-channel unit (with an emergency backup mode) is delivered with the LF26 four-cylinder, and a twin, independent-channel unit will be delivered with the LF39 six-cylinder engine. Two spark plugs per cylinder are stan- dard on both engines. On request, the newest, redundant dual-channel unit also can be ordered for the four-cylinder engineā€”a $1,300 (1,000 euros) option. D -motor's proprietary engine pickup sensor detects 4,096 pulses per crankshaft turn. This allows D -motor technicians not only to monitor the engine but also to sense acceleration pulses from each mixture ignition in the en- gine and address possible problems in each cylinder. This sensor/pickup is a D -motor product. The LF39 six-cylinder engine is running. During my factory visit in May, the six-cylinder engine was already running (more than 30 hours) on the D -motor proprietary test bench, so I could see and feel the smooth-running engine properties. I was allowed to see some (uncorrected) engine performance numbers on the dyno. I saw that the LF39 delivered 60 kilowatts and 275 Nm of torque at 2,000 engine rpm. In the meantime, this engine is being flown in a German helicopter and in D -motor test aircraft. After the factory tour, I was able to test-fly the LF26 engine on board the company's B.O.T. SC07 airplane. The flight was pretty short. But the engine was powerful and its vibration level is one of the lowest on the market today. The start sequence of the four-cylinder is very simple. Turn the fuel pumps on and select both channels of the This is the compact engine block (above), with the cylinders removed (below). The intake manifold is located below the engine; note the two short high-pressure fuel rails and four injectors.

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