Seaplanes and I have something in common. We burn most of our energy just getting up, and after that we barely need a thing to coast. Maxwell's M1 Hybrid has been designed to work like a triple espresso with six sugars and a bowl of porridge: electric motors give it a six-minute rush to leave the water, then small diesel engines calmly carry a ton of cargo up to 1,150 miles (1,852 km).
"Conventional aircraft must carry engines sized for takeoff even though they use only a fraction of that power in cruise," says Florida's Maxwell Aircraft, which describes its solution as patent-pending.
Each of the amphibian's two propellers is driven by a two-stroke diesel – it ignites its fuel by compression instead of a spark, and runs on Jet A – mechanically linked through a liquid-cooled electric motor. The system, the company says, is designed to be driven by either or both electric or Jet A energy.
The pair can, theoretically, deliver up to 1,500 hp (1,119 kW), but not for long. "The 1,500 horsepower is restricted to take off and initial climb, or about six minutes of operation, thereby keeping battery weight to a minimum, but supporting the tremendous power needed to lift a full ton of payload off the water into the air," CEO David Dillon told New Atlas. In cruise, the two engines get by on about 300 hp (224 kW) combined.
The first version is a freighter called the M1-HC, with a 5-ft (1.5-m) cargo door for palletized loads. Maxwell is aiming for 2,000 lb (907 kg) of payload over 1,000 nautical miles (1,852 km) in a single flight. The plane is amphibious, so it can use waterways as well as rough strips, and the company pitches it for remote communities, island operations, disaster response and defense work.
The plane's airframe is made from carbon fiber and Kevlar, and is based on the Gweduck, a composite amphibian that first flew in 2009 and that Maxwell calls a fifth-generation evolution of the Grumman seaplane design. The company says composites also shrug off the salt-water corrosion that eats metal hulls.
Maxwell isn't the first to put a fuel engine and an electric motor on the same propeller. California-based Ampaire is flight-testing a Cessna Caravan with a turbodiesel and an electric motor sharing one prop, and claims it burns 54 to 57% less fuel than the turboprop version.
Bigger players are at it too. US defense giant RTX, which owns Pratt & Whitney, has been working on a similar hybrid for regional airliners, and plans to fly a Dash 8-100 in 2027 with a 1-MW electric motor that helps out on takeoff and climb.
Where the M1 stands out is the ratio. On paper, it has five times as much power for takeoff as for cruise. Dillon says the engines have already put in substantial time on the test stand, though he hasn't said whether the full hybrid drive has run.
"The first airframes are out of the Carbon Seaplanes factory," Dillon says. Maxwell expects to show the M1 at the Lakeland Air Show in Florida in April 2027, although "it will be at the show with standard Lycoming engines." The hybrid version is expected to follow in Q4 of 2027. So when the public first sees it, the M1 will be taking off the old-fashioned way.
Source: Maxwell Aircraft via PRNewswire
