Free for nonsubscribers\u00a0<\/strong><\/p>\n By Hanneke Weitering<\/strong><\/p>\n Aug. 26, 2026, \u00a9 Leeham News and Analysis\/AIN<\/strong>:\u00a0An experimental glider aircraft equipped with two of Whisper Aero\u2019s eQ250 electric ducted fans has achieved its first flights, the company disclosed last week.<\/p>\n Whisper conducted the flights last week at its flight-test facility in Crossville, Tennessee. Test pilot Zac Majors flew the aircraft, called the Whisper Powered Swift, across three flights totaling more than 130 minutes in the air. The company said the flight-test campaign met all planned test objectives.<\/p>\n Preparation included a phased campaign of progressively ballasted glider flights, aircraft integration testing, formal readiness reviews, and 1,000 hours of ground-based propulsion life testing, Whisper said. Those sorties mark the program\u2019s transition from gliding validation flights to powered test flights.<\/p>\n A single-seat A\u00e9riane Swift 3 glider, modified with two Whisper eQ250 electric ducted fans, made its first flights in August 2026. Photo credit: Whisper Aero<\/strong><\/p>\n<\/div>\n A modified A\u00e9riane Swift 3 glider serves as a flying testbed for propulsion technology that the company has been developing in Crossville since 2020. Whisper previously referred to the glider program as the Whisper Ultralight. Despite the earlier moniker, the modified version of the aircraft no longer qualifies as an ultralight under the FAA\u2019s Part 103 rules, which cap a powered vehicle\u2019s empty weight at 254 pounds and require no airworthiness certificate. Whisper flew the Powered Swift under an FAA special airworthiness certification instead.<\/p>\n Two eQ250 propulsors, each capable of up to 85 pounds of static thrust, powered the aircraft, drawing from five Electric Power Systems Epic 1.0 battery modules. The glider\u2019s 26:1 lift-to-drag ratio means it travels 26 feet forward for every foot it descends. That efficiency keeps it aloft longer on limited battery power, giving engineers more time per flight to evaluate propulsion performance, acoustics, and handling qualities.<\/p>\n Tennessee\u2019s state government awarded the company\u00a0a $500,000 grant last year<\/a>\u00a0to demonstrate quiet flight with the electric glider in partnership with Tennessee Tech University. Faculty and students there supported ground testing and system integration alongside engineers from Whisper and Portland, Oregon-based Flighthouse Engineering, according to the company.<\/p>\n For Whisper, the milestone arrives amid the start-up\u2019s pursuit of an unusually broad range of ambitions, from military drones to regional airliner concepts and even leaf blowers, all built around a single core product. During a recent visit to the company\u2019s headquarters and flight-test facilities in Crossville, executives laid out how those pieces fit together.<\/p>\n \u201cWhisper is building quieter, more efficient propulsion for next-generation aircraft, and we\u2019re doing it because we know that there\u2019s a challenge getting to lower noise and getting to the levels of affordability required, whether that\u2019s for defense or the civil world,\u201d Whisper co-founder, COO, and chief product officer Ian Villa told\u00a0AIN<\/strong>.<\/p>\n Whisper does not build aircraft, and says it never will. While other companies spend billions certifying complete electric and hybrid-electric aircraft, Whisper\u2019s roughly 80 employees focus on electric ducted fans, which it aims to supply to airframers across the civil and defense markets.<\/p>\n \u201cThere\u2019s already a really great breadth of start-ups who have emerged these last few years\u2014they\u2019re in the thick of it, certifying their eVTOL, certifying their airplanes\u2014and the big unlock we saw to get into this next generation of aircraft is propulsion,\u201d Villa said. \u201cWhile vertical integration may have been necessary in the early days, as the market matures and expands, there\u2019s going to be greater specialization.\u201d<\/p>\n John Huff, Whisper\u2019s head of ground test, framed the same choice in terms of risk. Supplying propulsion \u201cgives us an opportunity to service a wide range of customers, both commercial and defense, many different programs,\u201d he said. \u201cThat\u2019s a much more stable business model than where I have to have risk built up through the whole system, from propellers to motors to an airframe to avionics. We can do what we\u2019re great at, and then we can partner with other people who have the elements where they excel.\u201d<\/p>\n A full-scale mockup of the company\u2019s\u00a0Whisper Jet<\/a>, a nine-passenger regional airplane concept with an array of ducted fans embedded in its wing, stands in the Crossville facility not as a product but as a visual aid. \u201cWhen you have a new technology, it\u2019s hard for people to really visualize or imagine how you would incorporate that into their designs,\u201d Huff said.<\/p>\n Whisper says its fans are dramatically quieter than comparable propulsion systems, and the company\u2019s explanation starts with a number called blade passage frequency: how many times per second a blade disturbs the air, calculated from the blade count and rotation speed. That frequency carries most of a fan\u2019s tonal noise, and Whisper\u2019s design pushes it beyond what people can perceive.<\/p>\n \u201cOne of the things you\u2019ll see in a Whisper propulsor is a much higher number of blades in the fan, and what that does is change the blade passage frequency\u2014how often something disturbs the flow\u2014it makes it much higher in frequency,\u201d Huff said. \u201cThat\u2019s a big part of why the acoustics change, both in terms of how tuned our ear is to it, as well as how quickly it fades into the air.\u201d<\/p>\n Human hearing tops out around 18 kilohertz in young adults and declines with age, Huff explained, and the ear is most sensitive in the range of conversation. High-frequency sound also dissipates in the atmosphere far faster than low-frequency sound, which is why thunder rumbles across miles while a hiss dies within feet. Whisper\u2019s fans exploit both effects at once.<\/p>\n Villa said the company made that acoustic target its founding design principle rather than an afterthought. Its fan disc carries many short blades spinning at high rpm but relatively low tip speed, keeping the dominant tone \u201cpast human hearing, but still in a way that minimizes the sound pressure levels, and ultimately reduces the perceptibility and really the annoyance to the public,\u201d he explained.<\/p>\n The powered Swift flights gave Whisper its first real-world test of those claims. Flying at full throttle, the aircraft\u2019s propulsion system was quieter than the airframe itself, even at an altitude of 100 feet, the company said. On an early morning flight with an ambient noise level of 34 A-weighted decibels, the aircraft added only 52 A-weighted decibels. Whisper says that level will be necessary for aircraft to operate in rural soundscapes under the FAA\u2019s Modernization of Special Airworthiness Certification rule, known as MOSAIC, without disturbing the surrounding environment.<\/p>\n Majors said the aircraft handled well despite the added thrust. \u201cWhisper Swift was more thrust, quieter than the standard propeller version of the Swift, but still great handling\u2014could really do whatever I wanted with it,\u201d he said. \u201cLook forward to flying it again.\u201d<\/p>\n The Whisper Powered Swift aircraft, an experimental A\u00e9riane Swift 3 glider equipped with two Whisper eQ250 electric ducted fans, is pictured inside Whisper Aero\u2019s hangar at Crossville Memorial Airport (KCSV) in Tennessee on Aug. 6, 2026, the week before its first powered flight. \u00a9 Hanneke Weitering\/AIN<\/strong><\/p>\n<\/div>\n Precision manufacturing makes the design possible. \u201cThe guy that cuts our fan blades also makes heart stents,\u201d Huff said. \u201cThat gives you an idea of how delicate these are.\u201d<\/p>\n When embedded in the leading edge of a wing, the fans do more than push an airplane forward. \u201cThe motors accelerate the airflow over the top of the airfoil, and that\u2019s what gives you lift in an airplane,\u201d Huff said. \u201cBy doing this, we augment the lift and get very high lift coefficients for when we\u2019re trying to take off. So now you can have a short takeoff or a near-vertical takeoff, depending on how you approach it.\u201d<\/p>\n Whisper calls that wing integration JetFoil. In June, the company said that computer simulations show the blown wing achieving lift coefficients far beyond those of any conventional airfoil at very low airspeeds. Whisper has since backed some of that up on the ground, turning the fans\u2019 exhaust to steep angles on a full-scale test rig and demonstrating\u00a0near-vertical takeoff and landing capabilities<\/a>\u00a0on a test stand, according to the company. No JetFoil-equipped aircraft has yet flown in that configuration.<\/p>\n Whisper aims its propulsors at a sweeping range of applications: uncrewed aircraft from small drones to larger military cargo airplanes, light sport and MOSAIC-category airplanes, nine-seat Part 23 aircraft, and consumer products. Its Tone subsidiary plans to ship a $599 electric leaf blower this year built on the same fan technology.<\/p>\n On the military side, Whisper has held Department of Defense contracts since 2023, initially for quiet surveillance drones. In June, its work moved from surveillance toward offensive operations. Mach Industries of Huntington Beach, California, named Whisper as its propulsion partner on Atlas, an uncrewed strike aircraft the Defense Innovation Unit selected for its Runway Independent Maritime Expeditionary Strike program. Atlas is designed to launch from ships without large flight decks and operate over a range of up to 1,400 nm while carrying a 1,000-pound payload, according to Mach.<\/p>\n![\"\"](\"https:\/\/leehamnews.com\/wp-content\/uploads\/2026\/08\/Whisper-Aero-First-Flight-Horizontal-1-scaled.png\")
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