Is There A Future At Sea For Regional Aviation?

Electric aircraft startups are challenging conventional thinking about aviation and one of the more dramatic examples is Regent’s belief that seagoing wing-in-ground-effect vehicles flying between coastal cities could complement and even replace traditional regional air transportation.

Boston-based Regent is building a quarter-scale technology demonstrator of its seaglider, a vehicle that combines wing-in-ground-effect (WIG) aerodynamics with distributed electric propulsion and hydrofoil lifting surface technology. Sea trials with the 15-ft.-span, 400-lb. unmanned model are expected to begin by the end of 2021.

The startup plans to have a piloted, 12-passenger seaglider on the market by 2025 as a replacement for seaplanes and water taxis, followed in 2028 by a 50-passenger vehicle that the company sees replacing not only ferries, but regional turboprops and jets.

Operating a wing within ground effect by flying a few feet above the water reduces its lift-induced drag, so WIG vehicles are more energy-efficient than conventional aircraft while being faster than boats. Regent is aiming for a range of 180 mi. at 180 mph with batteries available today, increasing to 500 mi. as battery technology improves.

Regent’s seaglider concept tackles the traditional disadvantages of WIG vehicles, including a long takeoff distance and a low tolerance to waves. The hydrofoil bridges the gap between low-speed operation on the hull and high-speed flight on the wing, allowing the seaglider to accelerate to 45 mph to transit the harbor before becoming wingborne in open ocean.

Powered lift using distributed electric propulsion, with multiple leading-edge propellers blowing the wing, reduces stall speed to 45 mph and allows the seaglider to take off directly from the foil. Redundant digital flight controls manage the transition from hull to foil to wing and back.

“The biggest cities are often the coastal ones, the biggest airports are often the coastal ones, the hardest routes are the coastal ones because those are where you get stuck in traffic on the bridge or you are forced to take that very slow boat,” CEO Billy Thalheimer said in July at the Electric Aircraft Symposium organized by the CAFE Foundation and Vertical Flight Society.

Regent projects significant savings in energy and maintenance costs from operating all-electric seagliders versus conventional aircraft, as well as tax savings from switching to a maritime environment where operators do not have to pay for FAA air traffic control or Transportation Security Administration services, he said.

“We’re in the midst of discussions with several airlines now, and there are multiple operating models,” Thalheimer said. One is aircraft replacement, “which would make sense for seaplane charter and even regional airline operators.”

Another is hub feeding. “You could imagine flying into LAX [Los Angeles International Airport] and now being connected up and down the coast of California with a network of seagliders taking you on to your final destination,” he said.

The third operating model is as a “hub bandwidth alleviator,” Thalheimer said. Citing the example of Miami International Airport (MIA), he said the ability of large airlines to connect their hubs is being constrained by runway slot capacity.

“So we could imagine taking these small regional jets that occupy the runway for as long as a large, long-range aircraft and moving that traffic over to a regional seaglider network that services the region and therefore alleviates bandwidth at the hub airport and creates new revenue opportunities for larger hub-to-hub carriers. And seagliders can do these ranges with existing technology,” he said.

While Regent calculates a WIG seaglider can fly more than twice as far as an equivalent electric aircraft, the startup does not view it as an either/or choice. “We see it as an integrated, all-electric, multimodal future transportation system, where the aircraft will be operating from the airports as they do now, you’ll have fleets of electric cars and air taxis serving the city, and now seagliders can be that missing link to connect regional cities with existing battery technology,” Thalheimer said.

“Now we’ve colocated the transportation hubs, all these modes of transportation are sharing the charging infrastructure, and we’ve enabled single-stop shopping for this urban plus regional plus long-range connectivity,” he said. “This is the long-term vision that Regent is working to make happen.”