Electra has provided a glimpse of the airliner of 2050 with its hybrid aircraft concept capable of carrying more than 100 passengers while using electrification, advanced aerodynamics, and integrated airframe-propulsion design to improve efficiency and reduce emissions.
Hybrid aircraft concepts have been gaining traction for some time, but Electra wants to take the idea to a new level as part of NASA's Advanced Aircraft Concepts for Environmental Sustainability (AACES) 2050 program.
The goal is to move beyond simply bolting electric motors onto a conventional airframe powered by traditional engines. Instead, the AACES 2050 concept combines aerodynamics and propulsion in ways that improve both efficiency and environmental footprint while remaining compatible with existing airport infrastructure.
Based on an earlier MIT study called the D8, the AACES 2050 is instantly recognizable thanks to its "double-bubble" fuselage, which consists of two tubular sections fused together. The arrangement is essentially the same construction as the Boeing Stratocruiser of the 1940s turned through 90 degrees. The purpose, however, goes beyond increasing internal volume without increasing length. The design turns the airframe into a version of a blended-wing design where the fuselage provides a substantial part of the lift. This also puts less structural load on the wings and allows them to be smaller.
But the really clever part is the hybrid propulsion system. Beneath the wings are two turbofan engines that provide most of the thrust and generate electrical power. At the rear of the fuselage sit three electrically driven fans powered by integrated multi-megawatt generators connected to the turbofans.
That might seem a bit silly at first glance. Why use the jet engines to run electric fans when the engines can just create thrust directly? Why accept the losses associated with energy conversion?
The answer lies in aerodynamics. This configuration exploits the boundary layer of air flowing over the airframe to increase efficiency. The engines are suspended on pylons under the wings to position them away from the air flow so they can ingest clean, uniform, freestream air moving at the same velocity as the aircraft. Meanwhile, a thick boundary layer of slower-moving air forms over the fuselage and flows toward the rear, where it would normally create a turbulent wake and dissipate energy.
However, in the AACES 2050 design, the rear-mounted propulsor fans embedded directly into the fuselage ingest this low-energy boundary-layer air before it can form a detached wake. By re-energizing the airflow, the system reduces drag and recovers energy that would otherwise be lost to turbulence behind the aircraft. That boosts thrust efficiency, reducing fuel consumption and emissions and allowing the engines to be smaller and lighter for greater performance.
It's all very neat in theory, but in practice the design does pose a number of challenges for engineers in terms of power transmission, heat management, and noise generated by the electric fans, which can be pretty loud.
“The value of electrification in this concept is that it lets us put the propulsion where it couldn’t go before but does the most good,” said Dr. Parker Vascik, Director of Product Strategy at Electra. “We can radically improve how the airframe and propulsion system work together while keeping the aircraft grounded in real airline and airport operations. The goal is not just efficiency on paper, but concepts that we can actually build, certify, and use.”
Source: Electra
