Aircraft
Rotax is one of the world's principal suppliers of aircraft engines for ultralight aircraft, light aircraft and unmanned aerial vehicles. By 2017, more than 180,000 Rotax aircraft engines had been sold over more than 40 years. In the light aircraft class, in 1998 Rotax outsold all other aero engine manufacturers combined. Their four-stroke engines powered most U.S.-certified light sport aircraft when they first appeared around 2004. Over two decades later, Rotax engines remain the most popular line of engines for light sport and ultralight aircraft, and the second-most-popular (after Lycoming Engines) for U.S. Experimental / Amateur-Built (E/A-B) aircraft.
Two-stroke aircraft engines
Rotax air-cooled, two-stroke engines began appearing on ultralight aircraft in the early 1980s, with a pair of single-cylinder, 7.1 kW (9.5 hp) Rotax 185s powering the single-seat Lazair ultralight by 1982. Soon, the 19 kW (26 hp), single-cylinder Rotax 277 became the most widely used engine powering U.S. ultralight aircraft (and remains, for many, the only Rotax engine they can use to adequately power the aircraft and still remain within the FAA-mandated weight limits for ultralight aircraft which can be operated without a pilot's license).
Two-stroke Rotax model numbers approximated the engine's displacement (in cubic centimeters), and the first two digits (from the 277, on) are very roughly similar to the engine's horsepower (e.g.: The Rotax 447 engine displaces 437 cc, and is rated at 30 kW (40 hp)).
Subsequent evolutions of the early designs included the two-cylinder, two-stroke Rotax 377, Rotax 447, and Rotax 503, all in production by 1985 (the last of these, the 503, was discontinued in 2010-2011, by then the most popular engine it its class, and still widely used as of 2023). Later two-stroke designs included the Rotax 532 (circa 1984) and Rotax 582, both of which augmented the air-cooling with liquid-cooled cylinder heads.
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Most Rotax two-stroke engines were rated, recommended, or reported with a TBO (time between overhauls) of about 150-300 hours (compared to 1200-2000 hours for government-certified, conventional, four-stroke, light aircraft engines), though later models improved upon that some.
Four-stroke aircraft engines
Moving towards more demanding aircraft applications, Rotax, by 1989, developed a four-stroke, four-cylinder, engine: the Rotax 912, with versions eventually ranging from 60 to 75 kW (80 to 100 hp), followed by a turbocharged 115 horsepower Rotax 914.
Rotax four-stroke engines differ from conventional four-stroke aircraft engines by their unusually small displacement for the amount of power -- compensated for by higher than normal rotational speed (over 5,000 rpm). To reduce propeller-shaft speeds to normal aircraft propeller rotational speeds, (around 2300-2400 rpm) the engines use a reduction gearbox. They are also designed to accept motor spirit, with up to 10% ethanol content.
These engines were initially given a 600-hour Time Before Overhaul (TBO), less than traditional light aircraft engines. But operational experience and modifications to address specific reliability issues over time gradually extended the TBO to 2,000 hours. An independent 2022 statistical study of U.S. government accident data found that the Rotax 912 family had the lowest rate of failure of the six most common lines of engines used in registered Experimental/Amateur-Built (E/A-B) aircraft.
By 2014, Rotax had produced and sold 50,000 of 912/914 four-stroke engines. Later models increased power, with several variants of the 912 family, and a new 100 kW (135 hp) Rotax 915 iS.
The Rotax four-stroke aircraft engine line immediately dominated the emerging category of U.S.-certified "Light Sport Aircraft" (LSAs), powering most of them. One general aviation industry media reporter found that 70-80% of the 66,000 aircraft he'd identified, worldwide, used Rotax four-stroke engines. The 912/914/915 series also powers larger certified aircraft, including the Diamond Katana, and the twin-engined Tecnam P2006T and Leza/Lockwood Aircam.
Off-road vehicles
Can-Am Off-Road vehicles from Bombardier Recreational Products are equipped with Rotax engines.
Products
Aircraft engines
Rotax engines designed specifically for light aircraft include both four-stroke and two-stroke models.
Current models are:
Rotax 912 series, four-stroke
Rotax 914 series, four-stroke
Rotax 915 series, four-stroke
Rotax 916 series, four-stroke
Historical models no longer in production include:
Rotax 275, two-stroke
Rotax 277, two-stroke
Rotax 377, two-stroke
Rotax 447 UL, two-stroke
Rotax 503 UL, two-stroke
Rotax 532 UL, two-stroke
Rotax 535 certified two-stroke
Rotax 582 UL, two-stroke
Rotax 618 UL, two-stroke
Karting engines
The Rotax MAX engine karting engine is a two-stroke engine series, launched in 1997.
OEM engines
The company also produces unbranded engines, parts and complete powertrains for original equipment manufacturers (OEM). Uses include motor bikes and scooters, with complete engines which include:
Rotax 122
Rotax 123
Rotax 144
Rotax 500
Rotax 650
Rotax 804
Rotax 990
Rotax 1125
