April 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/287214

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Page 29 of 38

30 Vol.3 No.4 / April 2014 UNDER THE COWL Meet the New Rotax 912 iS Sport Engine The best ever Rotax 912 engine? BY MARINO BORIC THE LIGHT AVIATION ENGINE market has a new engine—the Rotax 912 iS Sport, which is being unveiled this week at the Sun 'n Fun Fly-In and Expo in Lakeland, Florida. The Rotax 912 iS Sport is almost identical to the 912 iS fuel-injected engine presented two years ago. Some dif- ferences between the iS Sport and the iS are visible on the engine's upper side, while other changes are software-based. The 912 iS Sport engine is not a completely redesigned 912 iS, but rather is the result of fine-tuning and careful improve- ment. The basic engine is the same: same power rating and TBO, same concept, same displacement, same look. So, what has changed? A new, bigger aluminum airbox is 1.1 inches (27 mm) taller than the old one and offers a higher volume. Also new are longer engine intake runners and thus slightly repo- sitioned ignition coils. The engine control units (ECU) are now driven by new software that has a different calibration. The result is that the new 912 iS Sport not only has better torque than the 912 iS but also is better than the carbureted 912 ULS engine. When the 912 iS engine was introduced two years ago, aviation engine enthusiasts were thrilled to see a much more modern engine fi tted with fuel injection for better mixture control, lower fuel consumption, and less pollution, but some were a bit disap- pointed because they expected a more powerful engine. The lower torque of the 912 iS engine—119 Nm at 5000 rpm versus 129 Nm for the 912 ULS—turned out to be a penalty, especially for heavier aircraft and hydroplanes. This disadvantage was perceptible at takeof when hydroplanes not only had to lift a heavier load but also had to deal with the drag of the water. The all-new 912 iS Sport not only obliterates the drawbacks of the 912 iS but also will deliver much more torque than the 912 ULS. The same aircraft fitted with the 912 iS Sport (instead of 912 ULS or 912 iS) will take off sooner, climb better, and burn less fuel (see the attached graphs). The Rotax 912 iS Sport engine automatically improves its 5000ft 912iSSportclimbwithfixedpitchpropeller 4500ft 4000ft 3500ft Altitude[ft] 3000ft 2000 f 2500ft 2000 f t 0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 Time[min] 912iSSport 912iS E A A E X P _ A p r 1 4 . i n d d 3 0 EAAEXP_Apr14.indd 30 3 / 3 1 / 1 4 9 : 4 5 A M 3/31/14 9:45 AM

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