Dhe single-engine caravan from Cessna is a classic. Equipped with a 675 hp propeller turbine from Pratt & Whitney, it is used worldwide as a passenger or cargo aircraft with up to twelve seats. Now she faces a new career. Founded in 2016, California-based Ampaire is equipping the aircraft with a retrofit hybrid-electric drive. In the future, it should be able to use up to 70 percent less fuel on short trips and, if the appropriate fuel is used, it will even be able to fly CO₂-neutral. On November 18, the machine took off from Camarillo Airport in California for its maiden flight.
The main engine now comes from Adenau in Rhineland-Palatinate. There, the company Red Aircraft has developed a liquid-cooled twelve-cylinder diesel with two turbochargers. It delivers 550 hp from a displacement of 6.1 liters and is already approved for use in aviation. This Red A03-300 engine drives a three-blade variable-pitch propeller in the Ampaire Caravan and is characterized by its fuel economy. If the machine is operated with Sustainable Aviation Fuel, SAF for short, instead of kerosene, it should even fly almost CO₂-neutral.
In a cargo box under the fuselage
In the converted Cessna Grand Caravan, the V12 is assisted by an electric motor during takeoff and climb. Its batteries are located in a cargo box under the fuselage, which normally houses the passengers’ luggage. Together, the electric motor and piston motor achieve about the same performance as the otherwise installed PT-6A propeller turbine, at least when starting. The aluminum engine with two banks of six cylinders is already in use in several aircraft.
Since a large number of the approximately 2,700 Cessna Caravans built so far are still in use worldwide, Ampaire is focusing on converting existing aircraft. Because the widespread model, which has been built for decades, is only being modified, those responsible hope to achieve a shorter approval period from the American aviation authority FAA as early as 2024. According to Ampaire, numerous conversion orders to the hybrid-electric version with future nine seats and the name Eco Caravan have already been received.
According to the American company, the main advantage of the conversion is an immediately achievable reduction in fuel consumption and CO₂. In addition, greater sustainability is achieved by using existing aircraft than by building a completely new design. Ampaire expects that it will be years before a charging infrastructure is set up across the board at all airports. With the conversion of existing Cessna Caravans, however, a positive environmental effect can be achieved quickly. In addition, future operating and maintenance costs should even be lower than those of the propeller turbine variant.
Importantly for operators, the range of the hybrid version is said to be the same or even slightly better than that of the turboprop. The Eco Caravan should be able to fly about 1600 kilometers.