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As Ampaire prepares to bring the converted hybrid-electric aircraft to market, the Eco Caravan made its first flight on Friday. As part of its flight-test program, the California-based startup aims to obtain an FAA supplemental type certificate for its modification kit in 2024 following the 33-minute sortie from the Los Angeles-area Camarillo Airport.

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Elliot Seguin, the test pilot, took off at 7:49 a.m. PST and climbed to 3,500 feet. Following that, the pilot throttled the aircraft down to cruise speed, reducing the load on both the combustion engine and the electric engine, before observing the temperatures and other sensor readings for about 20 minutes before returning to the airport at low power.

As expected, the Eco Caravan propulsion system performed well," Seguin said after the flight. The ride was smooth and quiet. There were no abnormalities in temperature or power output readings." 

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As part of the preparations for flight testing the first Eco Caravan prototype, Ampaire's Electric EEL technology demonstrator has been extensively tested. To assess factors such as the infrastructure requirements for hybrid-electric aircraft, this aircraft has conducted exercises with airline partners in Hawaii and the UK.

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In a long-term plan to support the electrification of larger aircraft, the nine-passenger Eco Caravan will be Ampaire's first market entry. Next in its sights is the 19-seat EcoOtter, a reworking of the DHC-6 Twin Otter, and beyond that Ampaire CEO Kevin Noertker sees potential for 30- or 50-seat hybrid electric regional airliners as the 2030s get underway.

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Approximately 3,000 airframes worldwide are available for conversion, according to ampaire, which can help customers find Caravans for conversion. There are at least 1,000 airlines interested in operating the reinvented green aircraft, Noertker said.

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To install the modification kits, Ampaire will use its own facility at Hawthorne Airport near Los Angeles and also a network of independent service providers. These will include Air France Industries KLM Engineering & Maintenance, which in October signed a memorandum of understanding to partner with Ampaire.

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At the heart of the Eco Caravan’s powertrain is the A03 compression ignition engine, which its manufacturer RED Aircraft said will be rated at 410 kW as part of Ampaire’s integrated parallel configuration with the 160-kW electric motors and battery packs. The German company, which was announced as a program partner during the EAA AirVenture show in July, said its engine will deliver twice the thermodynamic efficiency of a comparable turboprop engine. The net power rating of the overall powertrain is projected to be 570 kW, or 765 shp.

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The electric motor will provide power as the aircraft takes off and climbs to cruise altitude, at which point the engine would generally take over. Depending on an operator’s mission requirements, the electric motors could be used for cruise flight or to recharge the batteries, which can otherwise be charged on the ground.

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A parallel hybrid-electric drivetrain architecture by Ampaire allows the motors to either add torque to the propeller shaft, resulting in greater propulsion power, or remove torque, recharging the batteries like a generator. As Noertker explained, they don't do both simultaneously. "In all phases of flight, the combustion half of Ampaire's hybrid system provides a base load of power. During takeoff and climb, the batteries provide electricity to the motors which increases the total propulsion power of the system. During cruise, the motors can optionally pull power from the propulsion system in order to recharge the batteries like a generator."

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The Eco Caravan's Epic energy storage system was selected by Ampaire in September. In addition to providing an energy density of 200 Wh/kg, EPS's battery packs will last for more than 2,000 fast-charge cycles before needing replacement. In order to conserve passenger and cargo space, battery packs will be installed in a body fairing.

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In the future, Noertker hopes to see airlines struggling to achieve profitability on some routes unlock their potential with hybrid-electric aircraft, even restoring some "atrophied" services. Additionally, he expects air service to be available to communities that were previously without it. 

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A maximum range of over 1,000 miles is expected for the Eco Caravan. Among its many uses, the ubiquitous airframe is well suited for air freight as well as other missions, including emergency medical assistance.

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Essentially, the hybrid-electric Eco Caravan reduces fuel consumption by between 50 and 70 percent, with greater savings on short flights. Fuels that are sustainable and can replace jet-A can be used for the engine. 

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Ampaire expects to save airlines between 25 and 40 percent in direct operating costs compared with the existing Pratt & Whitney Canada PT6 engine. There are no specific flight-hour or seat-mile costs for the Eco Caravan yet.

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Noertker acknowledged that the ongoing war in Ukraine following Russia's invasion in late February has attracted the attention of aircraft operators that have been complacent about the need for new energy sources. There has been a rethinking of fuel costs. The price of jet-A correlates very closely with airline bankruptcy rates, which is very concerning. Rich Report quoted him as saying, "I would love to break that cycle, and I'm all about helping people and communities.".

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As batteries continue to advance, Ampaire is agnostic about the available energy sources for future aircraft. A hybrid-electric approach, Noertker said, solved the technology risk [compared with starting with all-electric propulsion] and enabled the company to upgrade existing aircraft with it. The fact that hybrid models like the Eco Caravan can enter service using current fuel supplies, which increasingly could include SAF, also mitigates risks from complex recharging infrastructure needs.

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This is why we're starting with conversions of existing aircraft fleets, and then we'll work with OEMs to make the system standard on new-build aircraft," Noertker said. We will have multiple [electric-powered] clean-sheet airplanes in 10, 20, and 30 years from now.

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Ampaire's website teases the Tailwind concept design as one of these. There have been no details released about this design, which appears to feature an intriguing ducted fan powerplant enclosing the rear of the fuselage and more ducted fans near the top of the fuselage.

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Decarbonizing the aviation industry has proven to be the most challenging. Battery weight and energy capacity limit the range of fully-electric aircraft. Hybrid-electric aircraft, however, can preserve the range and utility of today’s aircraft. That is why we are focused on hybrid-electric propulsion for a series of increasingly capable regional aircraft. It’s a way for the airline industry to decarbonize more quickly and also to benefit from lower operating costs.

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