NASA has awarded Lockheed Martin's Skunk Works a contract to design, build and flight test a Low Boom supersonic aircraft prototype.
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 fly at supersonic speeds, but create a soft "thump" instead of the disruptive sonic boom associated with supersonic flight today.
The aircraft will be built at the Lockheed Martin Skunk Works facility in Palmdale, California, and will conduct its first flight in 2021.
The X-plane is designed to cruise at 55,000 feet at a speed of about 940 mph and create a sound about as loud as a car door closing, 75 Perceived Level decibel (PLdB), instead of a sonic boom.
The X-plane’s configuration will be based on a preliminary design developed by Lockheed Martin under a contract awarded in 2016. The proposed aircraft will be 94 feet long with a wingspan of 29.5 feet and have a fully-fueled takeoff weight of 32,300 pounds.
The design research speed of the X-plane at a cruising altitude of 55,000 feet is Mach 1.42, or 940 mph. Its top speed will be Mach 1.5, or 990 mph. The jet will be propelled by a single General Electric F414 engine, the powerplant used by F/A-18E/F fighters.
A single pilot will be in the cockpit, which will be based on the design of the rear cockpit seat of the T-38 training jet famously used for years by NASA’s astronauts to stay proficient in high-performance aircraft.
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.
But the X-plane'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.
Phase Two from 2022 will see NASA fly the X-plane in the supersonic test range over Edwards to prove the quiet supersonic technology works as designed, its performance is robust, and it is safe for operations in the National Airspace System.
The Phase three from 2022 to 2025 – Phase Three begins with the first community response test flights, which will be staged from Armstrong. Further community response activity will take place in four to six cities around the U.S.