Electronic Ignition Aims for Six-cylinder Aircraft Engine Applications
Electroair’s electronic ignition system is now a factory option for Aviat Aircraft’s Husky utility piston single-engine airplane. Electroair added the Husky to its Supplemental Type Certificate (STC) approved model list just before EAA AirVenture Oshkosh, according to Michael Kobylik, president of the Howell, Mich.-based company. Electroair is working with Aviat on certification of the electronic ignition system for six-cylinder Lycomings in the Pitts Special and in Aviat’s Eagle biplane kit.
The company is partnering with Spencer Suderman, who plans to try to break the world record for inverted flat spins in his Pitts Special, powered by a six-cylinder Lycoming IO-540. To make it to the needed 74 flat spins, Suderman needs to be able to climb to 22,000 feet, and the Electroair ignition system will help overcome inherent weaknesses in magneto operation at high altitudes.
The Pitts installation will be used to complete the STC for six-cylinder Lycomings, according to Kobylik. Electroair is also developing an STC for the Continental 470 and 520 engines, which will likely be the first six-cylinder application to be certified in the coming months. The Continental STC will be followed by the Lycoming 540 series, then the larger Continental 550 series and later turbocharged engine applications. The six-cylinder kit will sell for $5,500.
Electroair’s electronic ignition system is already FAA approved for a large number of light airplanes powered by four-cylinder Lycoming engines and most four-cylinder Continental engines. “The list is very extensive,” said Kobylik. The four-cylinder system costs $3,400.
The STC’d system replaces one of the airplane’s magnetos with the Electroair EIS-41000 ignition kit (non-impulse coupling magneto replacement) or EIS-41000IC (replaces impulse-coupling magnetos). Benefits of the electronic ignition system include 10 to 15 percent improvement in fuel consumption, smoother operation and better high altitude performance because there is no degradation in quality of ignition electrics as there is with unpressurized magnetos in thinner air. The EIS system uses manifold pressure as a reference to optimize spark timing for the specific altitude.
“Our system uses an inductive coil,” Kobylik said, “which [produces] a very large spark that can be sustained over a long duration of time, 70,000 volts through 20 degrees of crank rotation.” Electroair’s timing curve is designed to be conservative, he added, to deliver better performance but not risk high cylinder head temperatures if timing is advanced too far. The EIS trigger wheel measures engine rotation every six degrees of crankshaft rotation, he said, “so we can adjust timing every 12 degrees. Our system is able to keep up with rapid throttle movement and it keeps the ignition point as close to the optimal spot as [possible].”
The powerful EIS spark has another benefit, and that is cleaning off sparkplug tips. While it may seem that 70,000 volts would wear out sparkplugs quicker, that isn’t the case, Kobylik said. “We’re putting out 70,000 volts over 20 degrees of crankshaft rotation. A magneto on a good day puts out 12,000 volts over five degrees of crankshaft rotation. When [our system] is firing on the piston in compression, it’s also firing on the corresponding piston on the exhaust stroke, zapping high energy across the plug. What fails plugs faster is carboning up and [then] trying to spark. The side benefit [of the EIS] is hitting plugs with a cleaning spark and knocking off the built up carbon so you see longer sparkplug life.”