Advancements in propulsion system technologies are improving aircraft engine performance in terms of thrust capability, reliability and safety, optimizing petroleum-based platforms and enabling the development of alternative systems that use cleaner forms of energy. Next generation power plant architectures are aimed at efficiency and sustainability and encompass a wide range of potential new configurations, including electric, turbo-electric and hybrid-electric systems, as well as the use of renewable liquid fuels. As these new systems and energy sources are being developed, innovations in digital fabrication, new metal alloys, composite materials and thermal barrier coatings are making gas turbine engines quieter, more fuel efficient, lighter and more durable while lowering CO2 emissions. The integration of the propulsion system with airframe aerodynamics and flight controls has also been effective in reducing energy consumption, suppressing noise and boosting performance.
Due to the inadequate energy density of batteries and power output of electric motors, liquid fuels and gas-powered systems will continue to be the only viable near-future option for commercial airliners, military transport planes and other large and high-performance aircraft. However, there are opportunities for electric propulsion systems in smaller, lighter, short-range aircraft. Distributed electric propulsion systems are composed of a series of electrically driven wing-mounted propulsors connected to an energy source or power-generating device such as a battery, fuel cell or turbine that generates electricity. These systems allow for flexibility in the placement, size and operation of the propulsive devices, which can be rotors/propellers or ducted fans.
Electric propulsion promises transformative aircraft designs with reduced fuel costs, longer maintenance intervals, and reliability, along with zero emissions. Hybrid-electric propulsion systems will likely bridge the transition from gas-powered flight to fully electric flight.