EAA Sport Aviation - April 2010

the Rotax 912, a water-cooled, horizontally opposed, four-cyl-inder, four-cycle engine with dual carburetors producing 80 to 100 hp. (See Firewall Forward, page 114, for more information about the 912 series engines.)

All Rotax engines are designed to run on autogas, but they can also use aviation fuel (100LL) if necessary. The 503 and 582 come with a pull starter, though all manufacturers offer electric starters as well. The 912 is always an electric-start engine. A safety feature of the electric-start option is that you can be sitting in the trike when you start it. If the throttle is open and you are outside the trike, pull starting the engine can lead to a runaway trike and/or injury by the prop to yourself or other people or objects in the area.

And where is the throttle on a trike? Typically trikes have two throttles—a spring-style, foot- operated throttle on the right side of the carriage, and a friction-style (think airplane) hand throttle that’s mounted on the right side of the trike at some convenient location on the frame of trike, typically positioned near the pilot’s knee. The foot throttle operates like an automotive accelerator, while the hand throttle operates like an airplane throttle—push in for more power; pull back for less power. Either throttle can override the other, which is why one of the major items on a trike’s preflight checklist is to make sure the hand throttle is all the way out.

Clockwise: Rotax engines are the most popular powerplants on trikes; an Airborne trike as shipped for assembly; panel space on trikes is limited leading to frequent use of multi-function electronic displays.