If you like the window seat while you fly, then maybe enjoy it while it lasts. Airbus has filed a US patent application for a new multi-fan jet engine design, which has the engine nacelles wrapping around the airplane's fuselage instead of suspended from the wing. Still very much a concept, the design is aimed at improving engine efficiency while keeping overall size down.

The popular conception of most airliners is that they are propelled by jet engines, though the pedantic will point out that what looks like a jet engine hanging off the wing is, in fact, a turbofan. The difference is that in a pure turbojet engine the aircraft is propelled by the thrust of the jet exhaust, as in the case of a fighter plane. This works, but it's very inefficient, so engineers came up with the turbofan engine, which has a turbojet engine as its core. The thrust from this helps move the aircraft, but it also powers a huge ducted fan on the front of the engine that collects air and pushes it over the outside engine to provide extra thrust more efficiently.

According to Airbus, the quest for ever more powerful and efficient engines has led to larger and larger turbofans that are rapidly approaching design limitations. The bigger the fan, the heavier the engine, the smaller the ground clearance, the larger the fan blades, and the more difficult it is to integrate the various parts of the machine.

Airbus's solution is to replace one big fan with a collection of little ones. It's not a new idea in itself, but Airbus has added a few refinements, such as geared rings on each fan that transmit torque directly or indirectly to one another while controlled by adjustable linear actuators.

But the most striking change is moving the engine nacelles from under the wings to inside them, or to the rudder, or even the fuselage itself. On the fuselage, the fans could hug close to the skin where they could scoop up the airstream boundary layer flowing over the aircraft to further improve efficiency. In addition, the smaller fans would make them stronger and place less stress on the airframe.

However, none of this would improve the view.

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