NASA just announced Lockheed Martin as the contractor to build and test the next supersonic aircraft. If everything goes to plan the Low-Boom Flight Demonstrator (LBFD) will be completed by 2021 and tested shortly thereafter. The 94' long plane, pictured above, will cruise at 55,000 feet at a speed of Mach 1.4. The goal of this vehicle is to validate methodologies for determining the affect vehicle geometries have on sonic booms.
In 2003, supersonic travel for civilians ended with the last flight of the Concorde. The Concorde only flew over water as the noise from the sonic booms were louder than what FAA regulations allowed. A goal of the LBFD is to have a sonic thump be below 75 Perceived Level decibels (PLdB), roughly the same decibel level as a garbage disposal.
Shock waves being measured on a T-38 (Courtesy of NASA)
To study the effects of a quiet sonic boom, you must look at how the shock waves coalesce over the length of the aircraft. Many wind tunnel tests performed at NASA have provided insight to the behavior of airflow around unique geometries at supersonic speeds. As the aircraft velocity increases, the amplitude of the shock waves increase. Preventing the coalescence of these shock waves by manipulating the vehicles geometry will decrease the noise the aircraft. Combining wind tunnel and shock wave tests with computational fluid dynamic models, scientists can get a good idea on the performance of various geometries of an aircraft, however, the only way to truly understand the phenomenon’s that occur is to test a real vehicle. That’s where we are today, a giant step for quiet supersonic travel.
Taken from NASA.gov, the LBFD program is divided into three phases with a tentative schedule:
- 2019- NASA conducts a critical design review of the low-boom X-plane configuration, which if successful, allows final construction and assembly to be completed.
- 2021- Construction of the aircraft at Lockheed Martin’s Skunk Works Facility in Palmdale is completed, to be followed by a series of test flights to demonstrate the aircraft is safe to fly and meets all of NASA’s performance requirements. The aircraft is then officially delivered to NASA.
- 2022- Phase two will see NASA fly the X-plane in supersonic test range over Edwards to prove the quiets supersonic technology works as designed, its performance is robust, and it is safe for operations in the National Airspace System.
- 2022-2025- 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.
Lockheed Martin has mentioned that construction of the vehicle will begin immediately. All parts of the vehicle, except the unique outer skin geometry and airframe, are commercially available parts. The landing gear will be from an F-16, the engine will be a F414-GE-400, and the canopy will be from a T-38. If successful, the program will kick-start opportunities to bring supersonic travel back in the commercial industry. However the technology will not scale to commercial sized aircraft, just the methodology to determine the geometry.
Note: Opinions expressed are those of the author and not of NASA.
Wind tunnel model of LBFD at NASA Glenn, (Courtesy of NASA Glenn)