The prospect of electrical planes has long been considered potentially transformative for the aviation industry both in terms of its environmental impact and the cost of flying. Planes charged with renewable energy would not use jet fuel, one of the planet’s biggest polluters. That means they also wouldn’t have to pay for jet fuel, the single biggest expense involved in flight.

Significant progress has been made in developing the technology it is hoped will lead to commercially viable electrical flight and billions of dollars poured into start-ups working on it. However, so far the biggest limiting factor has been the range achievable by such vehicles.

A breakthrough now appears to have been made with the announcement a flight made for the U.S. air force last month beat the previous record range for an electric plane by at least 100 miles. The flight was made by a so-called eVTOL (electric vertical takeoff and landing) plane developed by the start-up Beta Technologies.

Modelled on the aerodynamics of an Arctic tern, Beta’s Alia model is capable of flying up to 288 miles on a single charge. Last month’s flight to test its range and airworthiness was made on behalf of the U.S. air force and saw an Avia eVTOL and by two military pilots.

Beta Technologies was founded by Kyle Clark, a former professional ice hockey player and Harvard graduate in engineering who sees the Avia as a small cargo plane transporting air freight between suburban logistics centres. Nine of the aircraft have already been produced with another 50 in production.

Clark started working on Avia as a means to quickly transport organs for transplant over larger distances than previously possible. He was backed with start-up capital by Martine Rothblatt who made her own fortune as founder of the biotech firm United Therapeutics and Sirius Satellite Radio.

Beta Technologies is off to a strong start and has already sold ten Avia eVTOLs to the logistics giants UPS which are due to be delivered in 2024. The U.S. air force has also signed a $43 million contract for a small fleet of the planes and Amazon has also invested in the company.

The focus on cargo for now sounds like it is tactical rather than Beta’s ultimate ambition. Clark believes electric aircraft will take longer to gain regulatory approval to carry people. However, when they do, the Avia can be converted from a small cargo plane into a six-seater passenger vehicle.

He said:

“We’re actually going to win at the passenger game because by the time others are doing passenger missions we will have thousands of aircraft, millions of flight hours and a safe, reliable, vetted design. Our competitors will just be getting in with their passenger markets or passenger aircraft. And by the time we meet them — say 2026, 2027 or 2028 — where do you think people will want to put their family?”

The greatest challenge to face electric planes has been overcoming the limitations on range imposed by battery technology. The kind of batteries able to provide enough power for flight have also been extremely heavy, giving themselves more work to do to keep an electric plane in the air. Beta Technologies has improved on previous limitations through a combination of improved design, inspired by nature and specifically the Arctic tern, and the latest battery technology.

The Avia’s design also makes use of a larger number of small motors which has improved efficiency. The advantage conferred by larger numbers of smaller numbers was recently detailed in a paper published by Shashank Sripad and Venkatasubramanian Viswanathan, of Carnegie Mellon University. The paper examined five eVTOL models developed by start-ups and concluded the multiple motors approach used by three, models designed by Munich-based Lilium Jet, Californian start-up Joby Aviation, and Clark’s Vermont-based Beta Technologies, needed much lower levels of energy than expected over longer flights.

Clark also says the design decision to move away from more complex rotors that tilt for take-off and landing, a feature of many eVTOLs, has improved efficiency. Instead, the Avia has four fixed propellers mounted on booms that resemble the blades of a catamaran and run above wide wings that allow the plane to glide to a safe landing in the event of a loss of power.