Advances In Aircraft Propulsion

Bio-fuel technologies, driven by the dual motivations of fossil fuel depletion and climate change imperatives, are progressing at a rapid pace. The technological feasibility of using bio-fuels in aircraft engines has already been demonstrated amply. It is only a matter of time before the cost of bio-fuels, which is around three to four times that of equivalent fossil fuels, is brought down by technological innovations to lower than that of fossil fuel. Changes to existing internal combustion jet engines to switch over to bio-fuel would be minimal and easily achievable.

- A.K. Sachdev

IN RECENT MONTHS, spectacular advances have taken place in the technology-intensive arena of aircraft propulsion. The world’s largest aero engine ever, the GE9X, completed its flight tests on a specially modified Boeing 747 and is now being geared up to be test flown on Boeing 777-9 for which it is intended. The GE9X has a fan diameter of 134 inches. To put it into perspective, its diameter is more than twice that of the CFM56 family that powers a majority of the world’s single-aisle, narrow-body commercial aircraft families of Airbus A320 and Boeing 737. The other remarkable event was the test flight of Ampaire 337, the highest capacity hybrid electrical aircraft ever flown. Originally a twin-engine Cessna 337 Skymaster, the aircraft was retrofitted with the replacement of one of the internal combustion engines with an electric motor, resulting in a parallel-hybrid propulsion system. While the GE9X is a momentum-driven progression of internal combustion engines that guzzle up Aviation Turbine Fuel (ATF) in proportion to their size/ thrust, the Ampaire 337 is part of a technological campaign to find an alternative to ATF.