EPS | Flight Testing

Flight Testing

On May 2, 2014, Test Pilot Dick Rutan took to the skies over the Mojave Desert in a modified experimental Cirrus SR22 powered by the revolutionary high-tech diesel Graflight V-8 engine and soared up to 5,000 feet while completing a full 20 minute test regimen. The historic, groundbreaking flight of this paradigm-shifting engine was so quiet that Mojave Air and Spaceport Manager Stu Witt complained he could barely hear the engine noise above the roar of Mike Melvill’s chase plane, a self-built Long-EZ.


This marked the beginning of the Graflight’s lengthy flight test program, which will last several months with Dick Rutan managing the flights and putting the engine through its paces, racking up more than 40 hours over the next three months to meet the FAA requirements that will allow the Cirrus to fly beyond the vicinity of the Mojave airport.  Throughout the testing phase, EPS will be monitoring 80 different channels of data on the engine, focusing mainly on pressures and temperatures of oils and coolants, and closely monitoring intake and cooling air. The engineers will also be monitoring drivetrain vibrations, horsepower, and fuel economy in flight.


At the end of the test phase, EPS will have proven definitively that the fuel savings recorded in over 500 hours of ground testing is equaled or greater in actual flight. The team will also have a better perspective on engine wear and maintenance requirements and work on the engine’s pilot interface will begin, a process that will be managed and informed by Dick Rutan’s extensive experience as pilot in command. It took a team of five engineers working twelve hours a day for five weeks to install the engine in the Cirrus – a record according to Stu Witt and others on the airport grounds. Rumors of the engine’s fuel efficiency traveled quickly down the flight line in this famed aviation town and it wasn’t long before the EPS hangar attracted a host of curious visitors, many expressing interest in acquiring a Graflight V-8 for one of their airplanes. But Dick Rutan, accustomed to attracting crowds from his days with the famed Voyager around-the-world airplane, played it cool: “This is top secret,” he told the bystanders. “Now move along. We’ve got work to do.”


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