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Pre-production engine passes 100 hoursPre-production engine passes 100 hours

The EPS pre-production Graflight V-8 diesel engine has exceeded expectations so far, and is expected to exceed the 360 horsepower produced in test runs to date. Photo courtesy of Engineered Propulsion Systems.

A Wisconsin firm building a clean-sheet aviation diesel engine reports steady progress toward certification with no unpleasant surprises. The Graflight V-8, which was not adapted from an automotive design, promises new heights of power and efficiency.

Engineered Propulsion Systems President Michael Fuchs said in a Feb. 3 news release that the pre-production version of the Graflight engine has performed well in its first 100 hours of ground running. The design was refined based on concept design tests in 2015, which followed a public debut in May 2014 with a flight test that featured Dick Rutan in the pilot’s seat and Mike Melvill flying chase.

The company, founded in 2006 by Fuchs and Steven Weinzierl, both veterans of the automotive industry, has since hired more staff and begun FAA certification tests on the Graflight V-8 at its New Richmond development facility. 

“We spent considerable time tweaking the calibrations and adjustments to assure optimal performance,” Fuchs said in the Feb. 3 news release. “That’s the only way to reach peak efficiencies and maximum horsepower. We have turned up 360 horsepower so far and expect to reach higher as the software is enhanced.”

The engine was inspected with a complete teardown after five hours and a partial teardown after 30 hours of ground running, with “no major issues” uncovered, Fuchs noted. “This is encouraging since we incorporated hundreds of new mechanical components and systems.”

Testing of the pre-production engine began in September, and the company will ramp up run times as the tests continue. Rutan is expected to pilot the first flight test of the pre-production version in the spring.

The company also has been working on a U.S. Air Force contract awarded under the Air Force Alternative Energy Solicitation program.

“We are extremely proud that the EPS team and suppliers have reached this important milestone,” said Weinzierl, the company co-founder and vice president. “Clean sheet designs are essential for advancing powerplant technologies and our test runs have clearly demonstrated their merits.”

Jim Moore

Jim Moore

Online Associate Editor
AOPA Online Associate Editor Jim Moore joined AOPA in 2011 and is an instrument-rated private pilot who enjoys competition aerobatics.
Topics: Diesel, Technology, Aviation Industry

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