California-based eVTOL startup Kitty Hawk revealed its third aircraft today, with a video that shows the single-seat prototype leaping from the ground and flying freely around a valley environment, presumably near the company’s Mountain View headquarters.
The video is one of only a few so far that show an electric eVTOL aircraft in the air. While we know multiple programs are in active flight-test, most are executed in secret, and actual evidence of untethered flight — beyond basic hovering and maneuvering — has been hard to come by. Both Lilium and Beta have shown videos of their aircraft, but even those videos have so far been fairly limited in scope. The video from Kitty Hawk, which is funded by Google co-founder Larry Page and led by autonomy and mobility pioneer Sebastian Thrun, appears to show the widest maneuvering envelope yet.
The new aircraft, dubbed Heaviside, was first revealed in an article posted today at TechCrunch. It uses an eight-motor distributed-propulsion powertrain, with six motors on each side of the forward-swept wing, and two more on a nose-mounted canard. The propellers face the ground for vertical lift then pivot rearward for forward flight. The design uses a conventional fixed-wing aircraft tail assembly and a taildragger configuration, with small landing gear positioned just aft of the cockpit.
The forward sweep of the wings is perhaps the most striking feature of the aircraft. The configuration has been the subject of steady experimentation since the 1940s, most notably in the experimental Grumman X-29 fighter jet. Two samples of this airplane were flown by NASA and the U.S. Air Force in the 1980s, with the goal of evaluating the increased maneuverability afforded by the design. It proved highly unstable however, requiring early fly-by-wire technology to manage its tricky flight characteristics and a composite wing structure to resist aerodynamic stresses.
Though some aircraft, usually gliders, do have modest forward wing-sweeps, the purpose is usually to place the main wing spar as far aft as possible, allowing for more passenger or payload space in front of the wing. That appears to be the motivation for Kitty Hawk’s use of the design, since high maneuverability sought by the X-29 isn’t necessary for VTOL aircraft, especially ones aimed primarily toward the air taxi market. Still, the angle of the forward sweep is pronounced, seemingly close to the X-29’s 33 degrees. We’ve reached out the company for explanation and will update this piece with their feedback.
Otherwise, the aircraft appears to use a deliberately simplified approach to its design. The company’s two previously revealed programs, the single-seat, low-altitude Flyer and the 12-motor Cora, used fixed-position propellers, and while Heaviside uses pivoting propellers, the motors themselves remain fixed. The wing — as well as perhaps the fuselage — appears to generate most of the lift in forward flight, allowing the propellers to focus mostly on generating thrust alone. Additionally, whatever aerodynamic quirks the forward-swept wing might generate could presumably be negated by the “backstop” of the computer-controlled distributed motors, which can contribute to control and stability in addition to simple lift and thrust.
The video also demonstrates the low noise signature of the design. A comparison between a conventional helicopter flying at 1,500 feet and Heaviside at the same altitude shows a 22 dBa difference, with the helicopter registering 60 dBa and Heaviside just 38, making it barely audible. According to the TechCrunch article and echoed in the video, the acoustic spike during takeoff was minimal, lasting just 10 seconds before it reached a high enough altitude that the noise became negligible.
The article indicates that the aircraft has been flown both remotely and with a pilot on board, and that it has a current range of about 100 miles (160 kilometers).