Whisper Aero's Ultra-Quiet Electric Engines Power First Piloted Flights in Tennessee

Whisper Aero achieved a key development in electric aircraft propulsion by conducting the first piloted flights powered by its eQ250 electric ducted fan engines. These flights took place in Tennessee under a special airworthiness certificate granted by the FAA, marking a significant step towards quieter, more efficient electric flight. The company outfitted a modified Aériane Swift 3 glider, dubbed the Whisper Powered Swift, with a pair of these ultra-quiet engines and completed three test flights totaling 130 minutes of airborne evaluation.

Test pilot Zac Majors, who piloted the Swift during these flights, reported that the eQ250-powered glider delivered stronger thrust compared to its standard propeller counterpart, yet maintained excellent handling qualities. Majors highlighted the responsiveness and control of the aircraft in his comments, emphasizing the smooth and adaptable flight characteristics enabled by the new propulsion system. The flights averaged roughly 43 minutes each, allowing the team to thoroughly assess the engines’ performance and acoustic footprint.

The eQ250 is Whisper Aero’s flagship electric propulsion system, designed to produce up to 85 pounds of static thrust suitable for fixed-wing aircraft as well as larger Group 3 uncrewed aircraft systems weighing up to 1,320 pounds. Central to its design are 10-inch diameter ducted fans that offer a noise reduction of about 20 decibels compared to comparable quiet propulsion systems, while also promising roughly 20 percent higher efficiency. This combination targets short to medium regional air mobility missions from small airports, enabling faster and quieter point-to-point transport.

For testing purposes, the Swift’s naturally high lift-to-drag ratio of 26:1 made it an ideal platform to evaluate integration, handling, and acoustic performance. Power for the eQ250 units was supplied by five Epic 1.0 Energy battery modules from Electric Power Systems, Whisper’s partner firm. This energy package enables about 60 minutes of useful flight time plus a 30-minute reserve, aligning with the needs of trainer aircraft, eVTOLs, and short-haul commuter planes operating on tight schedules and small routes.

Whisper Aero emphasized that at full throttle and just 100 feet above ground, the electric engines emitted less noise than the glider’s own aerodynamic sounds. Early morning flight tests measured about 52 decibels of noise from the powered Swift compared to 34 decibels of ambient sound. Such low noise levels are essential to meeting FAA MOSAIC regulations for electric propulsion and adapting to operations in noise-sensitive rural and suburban environments.

Looking beyond initial flights, Whisper Aero plans to extend testing with the Swift before initiating evaluations with government and defense clients later this year. The company is under contract with the U.S. Air Force to develop autonomous, quiet aircraft for contested logistics missions, with flight trials scheduled for 2027. These efforts include scaling the eQ250 technology into larger drone and crewed platform applications.

In parallel, Whisper is developing the JetFoil integration, an innovative propulsion layout distributing multiple ducted fans along a wing’s leading edge to enable near-vertical takeoffs with minimal runway length. This concept aims to surpass existing tilt-rotor VTOLs by requiring half their thrust while doubling payload and range. The JetFoil could be retrofitted onto platforms like the de Havilland Twin Otter to enable hybrid-electric STOL and VTOL capability.

Whisper Aero’s Collaborative Logistics Aircraft program, aligned with the Air Force’s initiative to pair manned and unmanned systems, envisions aircraft carrying 500 to 3,000 pounds of cargo from austere airstrips. These designs could integrate up to 30 eQ250 engines with JetFoil technology, operating quietly at speeds of 250 knots and with reduced heat signatures. Initial flight tests of CLA concepts are slated for 2027 at White Sands Missile Range, progressing the technology toward operational use.

Beyond military applications, Whisper has outlined regional commercial plans for larger models powered by their ducted fan electric propulsion, including a Whisper Jet concept and a 100-seat variant. These proposed aircraft would leverage the core eQ250 technology to redefine quiet, efficient short-haul air travel, potentially transforming regional connectivity while mitigating noise pollution.