DeltaHawk-Powered Piper Seminole DX Advances Flight-Test Program

RACINE, WI — DeltaHawk Engines reports that the Piper Seminole DX development aircraft, powered by twin DeltaHawk Jet-A compression-ignition engines, has entered active flight-test and is making strong progress ahead of EAA AirVenture.

Following its successful first flight earlier this month, the aircraft has now completed multiple flights as DeltaHawk continues expanding the flight envelope, validating systems integration, and gathering performance data in support of the Supplemental Type Certificate program. The milestone reflects both the transition from ground development to flight testing and the rapid progress made by DeltaHawk and Piper in bringing a new propulsion option to one of aviation’s most established multi-engine training platforms.

The Seminole DX pairs Piper’s proven American-built twin-engine trainer with DeltaHawk’s American-developed Jet-A diesel engine technology. That all-American aircraft-and-engine combination brings a fresh approach to multi-engine training, offering flight schools and fleet operators a potential path to lower fuel consumption, simplified engine operation, and broader global fuel compatibility.

“We are very pleased with today’s first flight of the new Seminole DX, powered by DeltaHawk,” Piper said shortly after the first flight. “The Seminole DX will further expand Piper’s already comprehensive training fleet and provide multiple aircraft and fuel solutions for professional flight schools around the world. Interest in the Seminole DX has been overwhelming since its announcement at last year’s AirVenture, particularly from the European and Asia-Pacific flight training markets.”

Early flight-test results have been encouraging. During the aircraft’s initial 30-minute flight, conducted in demanding summer conditions of 91°F and approximately 88% humidity, corresponding to a density altitude of about 3,500 feet, the aircraft achieved an initial climb rate of approximately 1,700 to 1,750 feet per minute while maintaining adequate cooling margins. Both engines operated normally, with stable power delivery, satisfactory propeller and governor response, and no significant abnormalities reported.

The aircraft configuration includes two counter-rotating DeltaHawk engines driving three-bladed propellers at approximately 2,400 RPM, a configuration intended to help reduce noise while supporting strong operating efficiency. Preliminary indications point to cruise fuel consumption approximately 35 percent lower than a conventional Seminole, a figure that could significantly affect the economics of high-utilization multi-engine training if confirmed through the continuing test program.

“This program is moving from promise into proof,” said Jon Heup of DeltaHawk. “The aircraft is flying, the data is coming in, and the results so far give us a strong foundation as we continue progressing toward certification.”

Andy Oja, Airframe Integration Manager at DeltaHawk, added, “Each flight gives us more information about cooling performance, handling qualities, engine operability, and systems integration. The early results are encouraging, and the team has made meaningful progress heading into Oshkosh.”

With multiple flights now completed, DeltaHawk will continue expanding the test program, evaluating aircraft performance, reliability, and integration as the Seminole DX heads toward AirVenture’s opening day.