10 unique eVTOL aircraft that do things very differently
Electric VTOL aircraft stand poised to change your world, if you believe the hype around this new category of air transport. Greener, faster, quieter and vastly cheaper than helicopters, they promise to bring vertical commuting to the masses like never before, reshaping our cities and lifestyles in the process.
And right now, we're enjoying a fascinating creative period in the emergence of these next-gen air taxis. It won't be long before they're everywhere – a settled, reliable and frankly slightly boring transport option – or nowhere, a multi-billion dollar boondoggle that never took off, so to speak. My money would be on the former, but I've certainly been swept up in magical, futuristic tech dreams before and come out with egg on my face.
Until a weight of data declares a winning architecture, the floor remains open for interesting and left-field eVTOL designs that do things differently from the crowd, and with 2021 drawing to a close, we thought it might be time to gather some of our favorites together in a roundup.
The Big Bessie: Kelekona's 40-seat VTOL air bus
Most leading concepts are crystallizing around two- to seven-seat cabins, following the model of taxis – but Kelekona is from New York City, where mass transit is already a way of life, and this young company doesn't see why eVTOLs shouldn't carry a busload of people.
Kelekona's Thunderbirds-style lifting body design will seat 40, and its monstrous 3.6-megawatt-hour battery pack has the potential to deliver enormous range figures up to 375 miles (600 km) at speeds around 200 mph (320 km/h). What's more, Kelekona tells us in our interview from June that it'll land on the same sized helipads as a typical five-seat Joby. Remarkable.
The Tiny Tim: Zeva's one-person flying saucer
On the other end fo the scale, Zeva reasons that most people commute solo, so why waste weight and seats on passengers that aren't there? Starting out with the idea of creating something super compact, the Zeva team has proposed a single-person, tail-sitting UFO design unlike anything we've seen.
It stands upright on the ground, taking up about as much garage space as a motorcycle, then takes off vertically and tilts forward until you're flying head-first, Superman-style on your belly, over the traffic for up to 50 miles (80 km) at speeds up to 160 mph (257 km/h). If you can get past the vertigo, the view's going to be incredible.
The Cyclogyros: Austria's Cyclotech and Russia's Cyclocar
Instead of standard propellers, these machines use Voith-Schneider arrangements: fast-spinning barrels whose "walls" are formed by a series of variable-pitch wing blades. Using a swashplate arrangement much like what's on top of a helicopter, it's possible to continuously vary the pitch of the blades as the barrels spin, meaning that these things can increase, decrease or redirect thrust nearly instantly through 360 degrees, without needing to wait for motors to spin up.
Cyclotech is proposing a four-seat air taxi, and Russia's Foundation for Advanced Research is looking at a six-seat hybrid Cyclocar for military purposes, capable of 155 mph (250 km/h) and ranges up to 310 miles (500 km). Both have flown decent-sized prototypes.
The supercar: Urban eVTOL's Leo
Ground space will be at a premium once there are thousands of eVTOLs in the air, and Urban eVTOL believes a compact footprint will be an advantage if that comes to pass. Thus, it's created Leo, a three-seat double-box-wing design that it claims can offer 250-mph (400 km/h) top speeds and a wild 300-mile (483-km) range, while only running 66 kWh of battery, and fitting in a car slot.
In our recent interview, co-founder Pete Bitar tells us Leo will land on asymmetrically inflatable "cat's paws," and will also offer pilots the chance to enjoy some pretty extreme flight dynamics. Oh, and the pilot seat hangs from the ceiling so back-seat passengers can look down through a glass floor.
The Lego set: Talyn's detachable lift system
The trouble with typical lift-and-cruise eVTOL designs is that the lift system immediately becomes a draggy, energy-sucking pain in the neck once the aircraft's in cruise mode operating like a plane. So a pair of ex-SpaceX Falcon 9/Scaled Composites engineers decided to take a page out of the rocketry handbook and simply jettison the lift system once it's done its job.
Talyn's detachable lift system, essentially a big autonomous lift-and-cruise drone, will then fly back to base and sit on the charger, ready to rendezvous with another cruise stage, hook onto it in mid-air and bring it down gently when required. The cruise stage, meanwhile, burns none of its battery power in the VTOL phases of flight, so it's capable of an impressive 300-mile (480 km) range at 200 mph (320 km/h). A fascinating, if very complex, approach.
The featherweight box wing: ASML Aero's Vertiia
Australian company AMSL Aero tells us the Vertiia should be one of the lightest and most efficient eVTOL designs on the market, as well as one of the most affordable. Designed to cover the long distances typical in many Australian emergency flights, it'll debut running a hydrogen fuel cell system that'll carry five passengers up to 620 miles (1,000 km) on a tank, at speeds upwards of 186 mph (300 km/h).
This relatively narrow box-wing design, with energy storage in the wing tips, could end up as much as 1,000 lb (450 kg) lighter than Joby's S4, reducing energy use. And AMSL says another cost advantage lies in the long service life of the fuel cell system, which should outlast several battery pack replacements on a lithium-powered aircraft. The company will shortly have a full-scale prototype flying.
The super-efficient transformer: PteroDynamics' Transwing
PteroDynamics isn't immediately targeting the air taxi sector with this design, starting out instead on smaller unmanned cargo drones, but the company says its clever, dihedrally-folding Transwing system will be the most efficient eVTOL design of them all, with some other huge advantages to boot. Folded up in VTOL mode, it's got a tiny ground footprint, needs very little space for VTOL operations, and operates pretty much like a multicopter. Once aloft, it can then fold out a huge set of wings for highly efficient flight. Since the wings tilt as they fold out on their dihedral pivots, the lift props gradually become cruise props, making for a smooth transition.
PteroDynamics claims "Transwing aircraft have much greater range, endurance, and cargo carrying efficiency as compared to all other VTOL designs." And "given any aircraft footprint size and payload requirements, Transwing aircraft will fly several times as far as any VTOL competitor." You've really got to see the prototype video to understand the potential of this one.
The biggest rotors in the game: Karem's Overair Butterfly
Karem Aircraft has a wealth of experience in large military tilt-rotor aircraft, and "Dronefather" Abe Karem has started up another company, Overair, to make an eVTOL play. Where just about everyone else in the eVTOL space will be using plain ol' propellers or ducted fans, Overair will be deploying enormous tilting rotors with highly redundant, all-electric control over individual blade pitch.
Those massive rotors stand to deliver significantly more thrust per kilowatt of power than pretty much anything else on the market, which should give the Butterfly a handy efficiency boost in VTOL mode. In cruise mode, it'll have bigger props than any comparable conventional fixed-wing plane, so big that they'd drag on the ground if it tried to do a conventional landing.
The variable pitch rotors enable this thing to autorotate to the ground under certain failure conditions, or develop asymmetric lift on individual rotors to compensate if another is lost - Overair says it can fly vertically or horizontally with up to two rotors disabled, which is pretty amazing. It also claims that these large rotors, spinning slowly, will be "nearly whisper-quiet during all stages of flight."
The frontrunner by a country mile: eHang's EH216
The eHang EH216 isn't much different from the rest of the class in a technical sense. It uses about the simplest architecture in the game: a simple 16-prop coaxial multicopter. It'll only fly at 80 mph (130 km/h), and it's got a piddly 22-mile (35-km) range. But mark my words, it's different from the pack, because it's Chinese, and the Chinese aviation authorities have fast-tracked it for fully autonomous certification years ahead of anyone else on the market. So while nearly everyone else with a prototype is flying it remote-controlled, these guys have already made more than 2,800 manned trial flights, and they're starting to ramp up mass manufacture at a 6-acre (2.4-ha) factory in Yunfu.
Indeed, eHang's executive team says it hopes to have the EH216 fully type-certified and ready for its first commercial air taxi services within a few months. Nothing in America or Europe is targeting a date before 2023 – and even when they do get airborne, they'll be carrying the added weight of a pilot everywhere they go. China's willingness to take an "innovation mindset" and push autonomous technology forward could give eHang a five-, or maybe even ten-year head start on its international competition – and that might make this bog-standard manned multicopter the biggest outlier of them all.
Have we missed any of your favorites? Let us know in the comments below.