Diesel Engines Start Making Their Move Into Home-Built Airplanes With The Glasair Sportsman Demonstrating Low Fuel Consumption And Long-Range Capabilities

The use of diesel power in aircraft engines was experimented with early in airplane development. However, it never caught on because gasoline was plentiful and cheap, and the investment in diesel technology just didn’t seem worth it. Now, that has changed.

Glasair reported on their blog that on May 20, the first factory-test Technify 2.0 liter diesel-powered Sportsman took to the air. Test pilot Ben Rauk noted that the engine started easily and is exceptionally smooth. This version of the engine is rated at 155 horsepower using a single-stage, exhaust-driven turbocharger. Full authority digital engine control (FADEC) allows the pilot to set maximum power anytime full power is desired, without worrying about over-boosting the engine.

The first report is that it flies great. If you have been following diesel installations, you know that there are some gains and some drawbacks. The engine weighs more, and so does the fuel. Fans of the carbon-fiber Sportsman’s 850-lb full-fuel payload may wonder how this capability will be affected.

Here are the numbers based on early testing. At about 60% power, the diesel is burning 5 gallons per hour. With full main tanks, that makes the Sportsman a 5-hour airplane plus a 1-hour reserve, while carrying about 840 lbs. of payload. Fill the auxiliary tanks, and the Sportsman becomes about a 10-hour airplane including an hour’s reserve, still carrying about 700 lbs.

It’s reported that Rauk observed at lower altitudes, the lower horsepower affects takeoff roll and climb rate. However, as the airplane climbs, the benefit of the turbo becomes apparent. At 8500 feet, Rauk was seeing a 900 fpm climb rate. The engine held 100% full power until reaching 9200 feet, when the turbo power gradually began to drop off. At maximum power at 9500 feet, the speed was showing 137 KTAS.

Testing will continue in the weeks to come. Glasair says it anticipates that this airplane will be available through its Two Weeks To Taxi program beginning this fall.

The photo shows the test plane and Ben Rauk after the first flight.

(Image provided by Glasair)

FMI: www.glasairaviation.com