When UK-based Dowty Propellers, a GE Aviation subsidiary, began exploring propulsion designs that could meet next-generation aircrafts’ needs, it soon became clear that manufacturing processes would have to advance as well. Through its four-year £20 million digital propulsion research and development program (DigiProp), funded in part by the UK government, the company pushed its propeller designs, materials and production processes in entirely new directions.
Several market indicators guided DigiProp’s design direction. Among these was the disruptive movement away from larger aircraft to smaller air taxis intended for short distance travel. Allied Market Research has projected that the global air taxi market will grow from $817.5 million in 2021 to $6.63 billion by 2030, with a compound annual growth rate of 26.2%. The smaller size of air taxis provides greater opportunity for a shift to more sustainable electric vehicles, another critical market driver. However, this shift puts new structural and dynamic load demands upon propellers.
With sustainability as another market driver, Jonathan Chestney, engineering leader for Dowty, says, “We recognize that we have to squeeze every fraction of a percentage point of efficiency out of our propellers because that directly drives fuel burn or, in all-electric aircraft , mission length and the ability to carry more weight.”
In the past, Dowty might have pulled design inspiration from a tried and tested family of aerodynamic shapes due to the complexity of propellers. “A blade is not just about the shape of the airfoil as it moves up the blade,” says James Trevarthen, a senior composites engineer at Dowty. “You’ve got twists you must take into account, as well as the extent to which the blade might sweep forward and backward.”
Even a slight change in shape or weight can have tremendous repercussions on structural requirements, among other factors. Managing these shifts and identifying which one can lead to desired performance improvements becomes exponentially simpler when working in a digital twin, a data-rich virtual representation of, in this case, an aircraft propulsion system. By converting to a digital twin process, Dowty can model performance of blade design and material options and simulate performance before the component is built.
Simulation of varying shapes and materials allowed DigiProp to determine how to best meet the many competing aerodynamic requirements, as well as structural and dynamic loads while keeping the entire process cost effective. However, with the ability to simulate the performance of so many design possibilities, it became evident that new manufacturing processes would give Dowty the freedom to make the best solutions a reality. This drove the use of a digital twin into the factory environment.