American aerospace giant RTX is promoting a hybrid thermal/electric propulsion system that can be used on regional turboprop airliners. The goal is to improve the electrification efficiency of existing aircraft without replacing the airframe, and significantly reduce fuel consumption and maintenance costs.
In the context of the current transformation of the aviation industry, electric propulsion has attracted much attention due to its high torque, high efficiency and zero emissions. However, due to battery energy density, its application is still mainly limited to small commuter aircraft with limited passenger numbers and limited range. In terms of mass, the energy density of traditional aviation fuel is at least 20 times that of batteries. This means that once batteries are used to replace fuel, a large amount of payload and range will be "eaten" by the weight of the batteries. The actual range of most all-electric aircraft is often difficult to exceed 150 nautical miles (about 172 miles/278 kilometers).
What's even more troublesome is that the battery is "dead weight" throughout the flight. Traditional aircraft continue to use fuel during flight and the body becomes lighter, which is conducive to extending the range and improving efficiency; while the weight of an all-electric aircraft basically remains unchanged from takeoff to landing, and a considerable part of the power in the later stage is just used to "fly with the battery on its back." In addition, thermal management challenges for batteries and pressure on ground charging infrastructure add additional complexity to the development of electric aviation.
Against this background, Pratt & Whitney Canada, a subsidiary of RTX, is working with Collins Aerospace and the Canadian government to develop hybrid turboprop engines for medium-sized regional aircraft, trying to take advantage of electric propulsion without sacrificing performance. On March 3, 2026, the "RTX Hybrid Electric Flight Demonstration Aircraft" achieved integrated operation of the propulsion system and battery at full power for the first time on the test bed in Longueuil, Quebec, Canada, which is regarded as one of the key milestones of the project.
Different from the automotive hybrid solutions that the public is familiar with, this aviation hybrid system is not a series system of "engine power generation and motor drive". The RTX demonstration configuration combines a Pratt & Whitney PW127XT turboprop engine with a rated power of about 1 MW and a Collins Aerospace motor, also with a 1 MW class. Through a special reduction gearbox, the output of the two power sources is simultaneously superimposed on the same propeller shaft to achieve "parallel drive".
The core idea of this architecture is to use the electric motor to "smooth out" the power curve of the heat engine, so that the gas turbine can work in the high-efficiency range more time. In stages that require high power output, such as takeoff and climb, the motor can provide additional thrust support, so that the turboprop engine does not need to frequently increase or decrease rotation speed; during the cruise stage, it operates in a relatively constant and optimized throttling state. At the pilot operation level, this system can push the total output to 2 megawatts when needed, making the thrust reserve more sufficient.
The motor not only produces force when "pulling the aircraft", but can also be used as a generator in reverse during the descent phase to restore part of the power of the 200 kWh H55 battery system on board, forming a certain degree of "energy recovery". While recuperated power cannot completely offset the high power discharges during takeoff and climb, it can help "hedge" some of the losses in the overall energy ledger.
The goal set by RTX is to use this hybrid propulsion system to reduce the weight of the entire power unit compared to the traditional turboprop solution, reduce fuel consumption by about 30%, and reduce maintenance costs by about 20%. In terms of environmental protection attributes, the system is also designed to operate on 100% sustainable aviation fuel (SAF), providing aviation operators with more options on the carbon emission reduction path.
It is worth noting that the “selling point” of this system is not only efficiency and emission reduction, but also its modifiability. All parties to the project claim that the hybrid propulsion system can be directly integrated into existing regional aircraft models without the need to completely design a new aircraft body. This allows operators to gradually complete power system upgrades based on the existing fleet, taking into account environmental protection requirements and economy.
According to the plan, this system will continue to conduct ground testing in 2026, and then move to the flight verification stage. At that time, the test will be conducted by AeroTEC in Moses Lake, Washington, USA, using a modified Canadian de Havilland Dash 8-100 as the experimental platform.
Pratt & Whitney Electronics Project Manager Rémi Robache said that what the industry really cares about is not "filling the aircraft with batteries but flying it empty", but reducing energy consumption "per passenger mile" to a lower level. He emphasized that the goal is to build an overall more efficient propulsion system in the dual dimensions of fuel and electric energy to transport passengers from point A to point B using as little energy as possible.