Sport Expo: Rotax 915 iS Soon Ready For Rollout


Rotax is about ready to roll out its new 915 iS engine and it will soon be available in uncertified form as a powerplant choice for experimental amateur built aircraft and high-performance LSAs. At 141 HP max for five minutes and 135 HP continuous, the Rotax 915 iS occupies a unique niche for factory-provided engines.

Dean Vogel of Lockwood Aviation, which will sell and service the engine to both kit aircraft and individual builders, told AVweb in an interview ahead of Sport Expo in Sebring this week that market interest in the engine has been modest. “What this engine really needs to succeed,” he said, “is for someone to design a clean-sheet airplane around its capabilities.” It’s expected to be available in the first or second quarter of 2018 for full-kit prices in the $35,000 range.

And one of those capabilities is high-altitude performance. The 915 iS—essentially a higher-power variant of the 912 iS—is turbocharged with up to 45 inches of boost. It can maintain full power well above altitudes where normally aspirated engines are wheezing and its ECU is mapped to operate as high as 23,000 feet. The 915 iS uses the same ring mount as previous Rotax engines, but designers will need to find room for the engine’s intercooler. And also learn about and deal with more complex systems.

“I think they (Rotax) have done everything right, but it’s a more complicated installation,” said Sebastian Heintz of Zenith Aircraft. “It’s not like the engines we’re using now that you hook up the fuel and you’re ready to go. Firewall forward, the components are a lot more critical,” he added. Heinz said he’s most attracted to the light weight of the 915 iS. At 185 pounds, it’s less than half the weight of the typical engines Zenith uses in its aircraft. Heintz agrees that the engine is different enough to ignite interest in new airframes tailored to its strengths.

“From an efficiency standpoint, you could be flying at high altitude and burning five gallons an hour. It’s kind of fantastic if you think about it,” he added.