Supersonic passenger flights may return, but without the boom

Lockheed Martin has won a $247.5 million contract from NASA to develop a supersonic jet plane quiet enough to be allowed to fly overland. A test model is expected to make its maiden flight sometime around 2021.

Dubbed X-Plane, the supersonic passenger liner has been under development by Lockheed’s Skunk Works team since 2016. The aircraft is expected to cruise at an altitude of around 55,000 feet (17km) at Mach 1.4 speed (around 1,500kph at that altitude) while producing a noise level of 75 decibels at ground level, which is less noisy than regular city traffic. Supersonic airliners of the past – the Concorde and Russia’s Tupolev Tu-144 – were significantly louder at around 90 decibels and would be banned from overland flights today.

The noise of supersonic flight is so high due to a phenomenon called sonic boom, a roaring sound produced by overlapping shock waves from a passing aircraft. Lockheed seeks to address it by shaping the X-Plane hull like a paper plane to scatter multiple shockwaves and reduce their cumulative effect.

READ MORE: Putin eyes supersonic civilian airliner based on Tu-160 strategic bomber

The immediate goal for the company is to produce a low-boom flight demonstrator, a scaled-down version of the aircraft to test it in actual flight. The prototype is expected to be ready by the end of 2021. If all goes well, the project may be commercialized around 2025.

The idea to bring back supersonic passenger transport has been floating around for quite some time. Russia is considering adapting the design of its Tu-160 supersonic long-range bomber into an airliner.