Airbus Files Patent for New Trijet

In the 1970s and 80s, the skies were filled with trijets like the DC-10, 727, and L1011. But with their rear-mounted third engines, these models were noisy gas guzzlers, and gradually disappeared from commercial fleets as newer models came on the market. Which is why aircraft historian types are abuzz over Airbus' recent patent filing for a new trijet design.

The patent abstract describes the new Airbus design as:

A multi-engine aircraft having one engine positioned at the tail of the fuselage, may include rear tail units in a vertical longitudinal plane-of-symmetry of the fuselage. The tail engine is disposed in front of the rear tail units on the upper part of the tail of the fuselage. The tail engine is mounted, in a detachable manner, on a rigid supporting structure attached to the supporting structure of the fuselage. A lowering shaft, formed in the tail of the fuselage and plumb with the engine, is supported by the rigid supporting structure. The lowering shaft provides a passage for the engine between a high position corresponding to the operational position of the engine and a low position in which the engine is removed from the fuselage.

This patent addresses two major weaknesses of previous trijet designs -- fuel burn and cabin noise. The new design assumes three smaller engines able to meet or beat current two-engine planes on fuel efficiency, and the tail features a shield that channels noise generated by the rear engine away from the airplane.

It's worth pointing out that a new patent doesn't necessarily mean a new aircraft is on the way. Manufacturers often file patents for products they have no plans to build, just to ensure that competitors aren't able to use a similar idea.

Japan Airlines DC-10. Photo: Hyougushi/Creative Commons 2.0

DHL 727. Photo: PhillipC/Creative Commons 2.0

United L1011. Photo: United Airlines