NASA has awarded a contract for the design, building and testing of a supersonic aircraft that reduces a sonic boom to a gentle thump. Lockheed Martin Aeronautics Company was selected for the Low-Boom Flight Demonstration contract, a cost-plus-incentive-fee contract valued at $247.5 million. Work under the contract began 2 April and runs through 31 December 2021.
Under this contract, Lockheed Martin will Skunk Works will build a full-scale experimental aircraft, known as an X-plane, of its preliminary design developed under NASA’s Quiet Supersonic Technology (QueSST) effort. The X-plane will cruise at 55,000 feet at a speed of about 940 mph (1,513 km/h) and create a sound about as loud as a car door closing—75 Perceived Level decibel (PLdB)—instead of a sonic boom.
The answer to how the X-plane’s design makes a quiet sonic boom is in the way its uniquely-shaped hull generates supersonic shockwaves. Shockwaves from a conventional aircraft design coalesce as they expand away from the airplane’s nose and tail, resulting in two distinct and thunderous sonic booms.
The new design’s shape sends those shockwaves away from the aircraft in a way that prevents them from coming together in two loud booms. Instead, the much weaker shockwaves reach the ground still separated, which will be heard as a quick series of soft thumps.
It’s an idea first theorized during the 1960s and tested by NASA and others during the years since, including flying from 2003-2004 an F-5E Tiger fighter jet modified with a uniquely-shaped nose, which proved the boom-reducing theory was sound.
Once NASA accepts the aircraft from the contractor in late 2021, the agency will perform additional flight tests to prove the quiet supersonic technology works as designed, aircraft performance is robust, and it’s safe to operate in the National Airspace System.
Beginning in mid-2022, NASA will fly the X-plane over select US cities and collect data about community responses to the flights. This data set will be provided to US and international regulators for their use in considering new sound-based rules regarding supersonic flight over land, which could enable new commercial cargo and passenger markets in faster-than-sound air travel.
We’re honored to continue our partnership with NASA to enable a new generation of supersonic travel. We look forward to applying the extensive work completed under QueSST to the design, build and flight test of the X-plane, providing NASA with a demonstrator to make supersonic commercial travel possible for passengers around the globe.—Peter Iosifidis, Low-Boom Flight Demonstrator program manager, Lockheed Martin Skunk Works