Published on February 17th, 2019 | by Nicolas Zart
February 17th, 2019 by Nicolas Zart
Photo by Eric Adams ©, used with permission.
It seems not a week goes by without the introduction of another electric vertical take-off & landing (eVTOL) startup. Today is no exception, with Beta Technologies, an eVTOL startup from Vermont, joining the crowd.
Kyle Clark wasted no time gathering top-notch engineers from GE Global Research, Scaled Composites, and Tesla, among a few others, as well as the right tools and equipment to build what he sees as the ultimate eVTOL urban air mobility (UAM) vehicles, according to The Drive. The Ava XC is very different from many eVTOL designs we’re accustomed to seeing. It’s part airplane, part tilt-rotor, but nothing like an Osprey.
The Beta Technologies air taxi prototype looks more traditional than the futuristic eVTOL designs of late. His is a heavily modified airplane airframe with 90-degree tilting wings and ailerons supporting 8 electric motors on each end. The aircraft is perched on high landing gears, presumably to accommodate the tilting rotors.
Technically, the Ava XC weighs in a 4,400 lb (1,815 kilo), with a 35-foot (10.7-meter) wing, and has so far accumulated well over 180 test flights approved by the Federal Aviation Administration (FAA). And where was it hiding all these years? Under a two-year development shrouded under a secret cloak.
According to Vertical Mag, the Ava XC uses 124 kWh lithium-ion battery packs. Its top speed is 154 knots (177 mph). It will fly 150 miles (240 kilometers) on a full charge, but the production model should reach up to 290 miles (465 kilometers).
As to how safe it is, Clark says the Ava XC was tested at 72 knots and a maximum altitude of 100 feet, with winds as high as 25 knots.
The startup under wrap until this past week received undisclosed funding from United Therapeutics, which is led by SiriusXM satellite radio founder Martine Rothblatt. The Eva XC is not expected to come into production until 2024. And according to Rothblatt:
“We’ve seen seven percent improvements in energy density every year for the past several decades. We need 300 watt-hours per kilogram in order to reach a range of 250 nautical miles, which is what I’m asking for, and it’s a no-brainer to see that we’ll be there in just a few years.”
Clark says using electric motors means having constant torque at any speed and to a certain extent any altitude. The choice of a distributed propulsion system means the flight controls react with instantaneous thrust adjustments at any power level. You won’t hear otherwise here on CleanTechnica. Clark also believes that with an ultra-precise control at any speed and attitude, an eVTOL can safely cut power off, avoid collisions, and even freefall and recover from a stall.
As to how it is piloted, the Ava XC uses a hybrid flight control design with a collective lever in the left hand that modulates the speed of the propellers and thrust. Clark says the control is much lighter than a conventional helicopter collective. The traditional foot pedals control the rudder and clockwise/counter-clockwise differential of the rotors.
There is a right-hand sidestick for the mechanical flight control surfaces and the fly-by-wire controller for distributed propulsion. The right thumb controls a bump switch that tilts the nacelles that modulate the tilt angle and sink rate.
As to how it feels to fly the Ava XC, Clark says: “I liken it to a glassy water landing in a sea plane where you come in … and all you’re doing is looking at the VSI [vertical speed indicator] and you’re setting your sink rate. The same thing’s true when you’re moving this thing forward — if you can feel anything, you know you’re doing something wrong. So you start to bump that in a particular direction to either increase the vertical component of lift or the horizontal component of thrust.”
Beta Technologies, More than an eVTOL Startup
Clark definitely has big dreams for Beta Technologies. He is converting to electricity a vintage Enstrom 28FX helicopter to test the direct-drive electric motors for his Ava XC air taxi prototype. The startup is also working on a solar- and grid-powered recharging pad technology. Clark hopes to install its wireless charging stations in strategic places.
Clark says that Beta Technologies has an approved simulator-based training program designed to train powered lift test pilots. He believes it is the only one in the industry. The simulator is most likely due to having Austin Meyer, the creator of the popular flight simulation software X-Plane, on the team.
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