A U.S. startup is preparing to fly a full-scale, five-seat electric vertical-takeoff-and-landing (eVTOL) aircraft that is powered not by batteries or hybrid-electric propulsion, but by hydrogen fuel cells. The result is a vehicle the developers say can fly for 3 hr., up to 300 mi. between cities and not the short hops envisioned for urban air taxis.
FAA certification of the Skai has been underway for 10 months, says Brian Morrison, president and co-founder of Massachusetts-based Alaka’i Technologies. Founded in 2015, the startup is aiming for FAA Part 21.17b certification in 2020 and is funded through to production by a single investor, he says.
Aircraft uses hydrogen fuel cells for energy density and zero emissions
It has a simple design for low manufacturing and operating costs
Designed for simplicity and low production cost, the Skai is a multicopter with six motors and propellers mounted on arms above the cabin. “There are no fans, no wing, no movable surfaces,” explains Morrison. “We have designed it for automotive-scale manufacturing.”
The 4,000-lb.-gross-weight vehicle has three fuel cells producing a total of 450 hp using liquid hydrogen stored at 100 psi in a double-walled tank. “Only two fuel cells are required to maintain flight,” he says. The Skai can fly on five of the six motors and controllers and has a triplex autopilot for redundancy.
Alaka’i is using a new-generation fuel cell that is lighter than other automotive units, with greater power output. No batteries are required to handle transient loads, Morrison says, and the fuel cells provide peak power for flight control as well as sustained power for thrust.
There are two hydrogen tank options: 200 and 400 liters. With the larger tank, which weighs just 36 lb., the vehicle can carry a 1,000-lb. payload for up to 4 hr. “That’s a significant step up from lithium-ion batteries,” he says, adding that Alaka’i will provide a ground-mobile refueling capability initially, but is working with hydrogen producers to build a refueling infrastructure.
Skai will be piloted initially, but it is designed to be autonomous when rules allow. Credit: Alaka’i Technologies

Skai has been co-designed with BMW Designworks to carry a pilot and four passengers. “It has the ability to be completely autonomous when that is supported,” says Morrison. Alaka’i is developing its own autopilot and fly-by-light technology to interface with the motor controllers.
The startup selected fuel cells after studying and rejecting thousands of lithium-ion batteries, he says, citing an energy density for hydrogen of 147 MJ/kg versus 0.6 MJ/kg for batteries. “And we produce a clean vehicle that does not contribute to pollution,” Morrison notes. Hydrogen fuel cells emit only water vapor.
Compared with most eVTOL developers, Alaka’i is aiming at a different operating model. CEO Steve Hanvey created air taxi operator SATSair, which grew out of NASA’s Small Aircraft Transportation System (SATS) program. Alaka’i board member Bruce Holmes played a key role in the SATS program and worked for DayJet, which provided on-demand transportation using Eclipse very light jets.
The full-scale prototype has three liquid-hydrogen fuel cells powering six motors and propellers. Credit: Alaka’i Technologies

Skai is aimed not at 15-30-min. urban flights, but longer intercity trips of the type flown by SATSair using Cirrus SR22s. Alakai’i plans not only to manufacture aircraft, but to set up and run air-taxi operations. “We already have an app, similar to Lyft and Uber,” says Hanvey. “We’ve done a lot of the leg work.”
SATSair and DayJet folded during the 2008 economic crisis, but the difference today, Holmes says, is the connectivity available to link passengers and aircraft. Alaka’i also is aiming for a paradigm shift in aircraft operating cost. “Skai will have 1/8th the cost per seat-mile of an [Airbus] AS350 helicopter,” says Hanvey.
“We have a simple aircraft that we can build at quite a low cost, we only need to buy a small amount of fuel and do not have maintenance costs,” he says, adding that more than 90% of the fuel cell can be recycled at the end of its life.
With first flight of the prototype imminent, Alaka’i plans to fly the first certification aircraft in 5-6 months. “We have such a simple architecture that our expectation, barring unexpected requirements, is we will certify next year,” says Morrison.