Boeing was recently granted patents on a number of ideas that point to a focus on quiet airliners for the future. The main concept includes shielding the engines from the ground by placing them above the wing or fuselage.

In its filings with the United States Patent Office, Boeing also mentions that the capability of reducing the heat signature of an aircraft from the ground is possible using the creative engine placement. The reason for shielding the heat is spelled out clearly in patent 7,900,865: “Heat is undesirable particularly in both military and civil aircraft, which may be tracked by ground-based missiles that seek heat in the form of infrared radiation.”

Another noticeable feature of the design is the forward-swept wings and the use of canards at the front of the aircraft.

In addition to these somewhat unconventional ideas, Boeing was granted patent 7,900,868, which focuses on reducing the sound of an aircraft as heard from the ground. This patent puts the engines on top of the wings. But instead of using an all-new design, a more traditional design is simply altered with the engines mounted on an extended wing platform near the fuselage.

Boeing points out in its patent that with the engines hanging from the bottom of the wing as is typical on most airliners, there is no barrier between the noise produced during flight and the ground.

The noise from the engine also interacts with the underside of the wing, providing a bit of an amplifier for the sound of burning jet fuel. The diagram below shows that with the new configuration, the engine and much of the sound is shielded from the ground when the airplane flies overhead.

The design also uses vertical stabilizers placed on either side of the engines to further reduce the noise signature.

The idea of shielding engine noise from the ground has also been explored by Airbus in a concept unveiled last year.

It’s unlikely any of these ideas will find their way onto Boeing’s next airliner, a replacement for the 737 expected to fly sometime around 2020. But with ever increasing noise restrictions around airports, quieting airliners will continue to be a priority for new designs.

Images: United States Patent Office