Ampaire, a developer of hybrid electric aircraft propulsion, has teamed with Ikhana Aircraft Services to explore modifying Twin Otter airframes to fly with that technology. California-based Ikhana is known for engineering modifications for Twin Otters, including having received an FAA supplemental type certificate for its DHC-6-300HG with a maximum gross weight increase to 14,000 pounds, from 12,500 pounds.
The two companies have launched a NASA-funded study to explore the “electrification“ of the Twin Otter. Under NASA’s Electric Aircraft Propulsion program, the two companies will evaluate various options and produce plans to assess the cost, schedule and risk mitigation for the planned development. The partners’ goal is to be able to put a hybrid-electric version of Ikhana’s 19-seat RWMI DHC-6 300HG Twin Otter. The 1,500 hp/1 MW power specifications of the current aircraft’s Pratt & Whitney Canada PT6 engines meet the criteria for the NASA program.
Ampaire is looking to accelerate the introduction of electrically powered aircraft by modifying existing models, rather than seeking to develop completely new designs. Its first project has been to produce a hybrid-electric version of the Cessna 337 piston single called the EEL. Ampaire first flew the EEL in June and since then has relocated its electric motor from the rear of the aircraft to the front. Both aviation gasoline and electric motors are rated at 210hp (160 kW). The electric motor is throttled via software so that the stock engine can keep up with it.
According to Ampaire, it is moving the battery pack to a specially designed pod underneath the aircraft, which the landing gear can handle. This configuration frees passenger space inside the EEL.
Ampaire co-founder and CEO Kevin Noertker told AIN choosing the Twin Otter for its next hybridization was a logical step up. The company had been looking into re-engining a 9- to 19-passenger capacity with the widest appeal to potential clients.
NASA’s project aims to reduce noise, fuel burn, and emissions. Brice Nzeukou, Ampaire’s product manager, told AIN the company will not only meet these aims but exceed them. It believes that the NASA Viking Twin Otter hybridization will mean that the company can scale up the technology to single-aisle airliners soon after. Ampaire’s project falls under FAA Part 23 rules, which presents the prospect of a path towards aircraft electrification. Nzeukou says it will enable true emission and energy reduction as it scales up to regional aircraft and reach 50 to 100-seater airplanes.
Ampaire CEO Kevin Noertker said, “We see NASA’s support as validation of Ampaire’s retrofit strategy. It’s a low-risk, achievable path to a hybrid/electric, and ultimately a full-electric, future."
Ikhana president and CEO John Zublin said the airframe is ideally suited to this development. He said, “The Twin otter is a unique multi-role aircraft with proven flexibility to operate as an urban commuter, a back-country bush plane, and in various special-missions applications. It’s an ideal demonstration platform for electrification technologies and as a certified product will have broad market appeal in its own right."
Noertker added, "Ampaire’s study of the aviation market indicates that one-third of aviation emissions are accounted for by route segments of less than 1,000 kilometers [540 nm]. We have the technology today to address these route segments on aircraft up to 19 seats, while hybrid electric solutions will come for larger aircraft in the longer term. We can have a hybrid electric Twin Otter in service in just a few years."