Whisper Aero has completed the first piloted flights of its eQ250 electric ducted-fan propulsion system aboard a modified Swift 3 glider, marking a move from ground testing to flight testing for the company’s electric propulsion technology.”
Whisper chose the Swift because its 26:1 lift-to-drag ratio allowed evaluation of, “Propulsion performance and aircraft integration under FAA special airworthiness conditions.” The light weight and low drag of the craft ensured good performance on the twin propulsors. With a gross weight of “over 600 pounds,” the Swift is no ultralight. But wifh 170 pounds of thrust push it quietly along, performance is sprightly, including a 1,200 foot-per-minure rate of climb.
Taking a bit of editorial license, we’ll assume a gross weight of 650 pounds for the Whisper Swift, including 16 pounds each for the propulsors, more for batteries, and additional for the five Electrical Power Systems Epic 1.0 Energy Modules. Even with the added weight, the flying wing creates only 25 pounds of drag, easily overcome by Whisprt’s thrust, reported by the compqny as greater than that of propeller alternatives.
Truly Whispering
The significance of this story comes from whether the propulsors live up to their name. Fulfilling expectations, Whisper Aero reported that the aircraft produced 52 dB(A) during early morning testing at a 100-foot altitude, compared with an ambient level of 34 dB(A). Such acoustic quietude would enable airports to be built closer to residential areas, enhancing the utility of regional air parks.
The project received support from Tennessee Tech University through a $500,000 Transportation Network Growth Opportunity award from the Tennessee Department of Economic and Community Development.
Following preparations including 1,000 hours of “Propulsion life testing,” test pilot Zac Majors flew three planned flights totaling more than 130 minutes.
Test flights will continue in Tennessee, and results will be shared with other facets of the Whisper Aero organization. Military and civilian partners will benefit from the continued testing, and airframers will obtain vital data for integrating Whisper’s power systems in a variety of aerial vehicles. Whisper itself has no intention of producing aircraft, and will continue to develop quiet power for future flight.