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Rotax Hybrid Engine

Hybrid Aircraft Propulsion, I

A number of companies are developing electric power plants for aircraft, basically for powered gliders and small ultralight aircraft. In most of these designs the power plant is of secondary importance and the aircraft can fly, or better, glide considerable distances without an engine purely by its basic aerodynamic properties.

Hybrid propulsion means a combination of electric and internal combustion motors. The idea is that you use the best of both worlds to come to at least the same but preferably an even better economic result. In the case of aviation this means: lower fuel consumption, lower emissions and as such a cleaner flight with less impact on the environment.

Keep in mind that this must mean the whole picture from fabricating the engines, maybe batteries (chemicals) and all that is needed for the installation and final disposal/ removal/ recycling of those items.

Hybrid Developments Part One

After the initial electric aircraft boom, which deflated quickly after realizing that increasing battery density is more or less of a dead end, we see more companies aiming for some sort of hybrid propulsion system for aircraft. This page tries to sum all those efforts to give us an insight in this technology and where it currently stands and who is developing what.

2020: AVweb presented a podcast about the future of hybrid propulsion systems and battery driven aircraft and which are technically and commercially viable. Very interesting, see more here: Electric Hybrid Aircraft Drives.

Tecnam P2010 H3PS

Feb 2022: Tecnam announced that they have successfully flown their P2010 hybrid aircraft on Dec. 21st 2021. The propulsion system consists of a Rotax 915iS connected to a Roll-Royce 30 kW electric motor. This will demonstrate if this combination can be flown. It is not intended for sale on the market. See the flight video on YouTube: P2010 H3PS maiden flight.

Surf Air, California

2021: They signed a deal with Cessna to purchase 100 Cessna Grand Caravans with the goal to install hybrid-electric power plants in them, in an effort to 'decarbonize' aviation, little do they know that life on this planet is carbon based. Anyway, read more in the article from LA-Business: Surf Air Mobility. Be prepared for marketing talk.


2021: They were busy working on a 2.5 MW Power Generating System demonstrator in Trondheim Norway. It now has been moved to Bristol in the U.K. for further testing. This generator is designed to power regional airliners with hybrid-electric propulsion systems. The unit is the size of a beer keg and is ground breaking of whats physically is possible. More info in the article from AIN-online: Rolls readies Propulsion Trials. In December 2021 the PGS1 (AE2100 engine generator) reached the 1 MW (megawatt or 1300 BHP) milestone.

deHavilland Dash 8

2021: Pratt & Whitney Canada is working together with deHavilland Canada to test a hybrid-electric propulsion system on a Dash 8-100 aircraft as a technology demonstrator. The program is expecting ground testing in 2022 and hoping for flight testing in 2024. The electric motor and controller is from Collins Aerospace and Raytheon Technologies. This hybrid drive is expected to save 30% in fuel burn compared to a modern turboprop.


2021: This U.K.-government backed company is using a pair of Dornier 228 twin turboprops as test aircraft for the 600 kW hydrogen-electric powerplants. One aircraft will fly in the U.K. and the other in the U.S in California. The fuel tank will contain 100 kg hydrogen and has an expected 500 mile range.

This is a follow-up from the Piper Malibu that had a 250 kW hydrogen hybrid drive. That aircraft was damaged during landing on April 29th.

Sling Aircraft, South Africa

2021: Sling is also developing an electric, hybrid aircraft (e-Sling) which has three battery packs (based on 18650 cells) cooled by silicone oil. One in each wing (in place of the fuel tanks) and one in the engine compartment together with a range extender. Electric capacity is 55 kWh. The airframe used is based on the TSi low wing model.

VoltAero, France

Update Sep 2021 from AVweb: "On Monday (Sept. 13), VoltAero's Cassio 1 demonstrator hybrid-electric aircraft made its first English Channel crossing, and is participating in this week's ACE21 Air Charter Expo at London Biggin Hill Airport." The flight started in France at Calais airport for a stop at Cranfield University before going to its destination.

VoltAero develops the Cassio 1 aircraft (basically a Cessna 337 Skymaster) installed with two electric motors (Safran EngineUS 45). The rear engine functions as a generator (170 kW) with a 150 kW motor for the rear propeller, the front engine should be removed for production. They plan deliveries in 2022, lets wait and see.

That early test design has been abandoned in favor of a new canard model with a twin tail. More info on the website of VoltAero.

The company also is manufacturing a hybrid power module consisting of a 300 kW V-6 engine combined with three (3) electric motors of 60 kW each. This power train has been developed in the Cassio 1 aircraft.

In 2015 they flew the E-Fan, developed together with Airbus, across the channel, the E-Fan was a twin electric aircraft with batteries reaching 60 kW.

United Technologies - DASH 8-100

2019: UTC is developing an electric assist (hybrid) drive for the Bombardier Dash 8-100 regional aircraft where the electric motor will support the gas turbine during takeoff and climb. Fuel savings up to 30% can be reached but this is partly caused by the more efficient gas turbine. Operational range is almost halved to 600 nm due to an increased empty weight (source: Flight Global, March 2019).

Airbus & Rolls-Royce

PARIS 2019: These two players are on track to develop a hybrid Bae 146/TJ100 airliner into an E-Fan X hybrid electric demonstrator in 2020. Siemens is also involved in this project with developing the drive train for the demonstrator aircraft.

Ampaire Inc

This California based company is using a Cessna 337 SkyMaster and they have removed the rear engine, installing a battery powered electric engine to reduce emissions and noise. It's one of the largest hybrid aircraft to date (their claim in 2019). They also say the third revolution in aviation being electric. We can only hope they know something about battery physics (that we don't) making this possible. More here: https://www.ampaire.com.

Oct 2020: They completed their first cross country flight, the distance was 341 statue miles. More in the article from AVweb here: Ampaire Cross Country.

Aug 2021: This aircraft will be tested in Scotland on a route from Kirkwall and the Orkney Islands town of Wick. The aircraft will have an electric motor in the nose with batteries in the baggage pod under the belly. A standard Lycoming 540 sits in the back.

Written by EAI.

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