NASA’s “Quiet Supersonic Flights” over Galveston helps develop future commercial supersonic air travel
Imagine flying from Los Angeles to New York in 2.5 hours instead five hours or flying from Houston to Dubai in 8.5 hours instead of 14 hrs. 40 minutes. NASA is currently conducting a series of supersonic technology research flights over the Galveston/Texas area (currently Galveston is the only U.S. city in the test), in support of the agency’s Commercial Supersonic Technology Project. Over 20 flights took place in November, using a NASA F/A-18 aircraft taking off from Ellington Airport, performing low boom inverted dives maneuvers off the coast of Galveston. The sonic boom noise from these dives is collected at various points all over the area. Thedata collected will help build a future supersonic X-59 jet that will fly faster than the speed of sound over land and water.
How is a sonic boom like a vessel bow wave?
A sonic boom is the sound associated with the shock waves created whenever an object travelling through the air travels faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear.
When an aircraft passes through the air it creates a series of pressure waves in front of the aircraft and behind it, similar to the bow and stern waves created by a ship. A bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship’s wake. A large bow wave slows the ship down, can create a risk to smaller boats, and cause damage in the harbor to shore facilities and moored ships. Ships are designed to produce as small a bow wave as possible. These waves travel at the speed of sound and, as the speed of the object increases, the waves are forced together, or compressed, because they cannot get out of each other’s way quickly enough. Eventually they merge into a single shock wave, which travels at the speed of sound, a critical speed known as Mach 1, and are approximately 1,235 km/h (767 mph) at sea level and 20 °C (68 °F).
During the NASA testing, the U.S. Coast Guard issued two different types of broadcasts messages to the maritime community when a sonic boom test took place so the mariners would not mistake a boom for an explosion. Both broadcasts began on VHF Ch. 16 and switched to Ch. 22A.
The first was a regularly scheduled marine broadcast that occurred four times a day at 4:50 AM, 6:50 AM, 10:50 AM. and 4:50 PM:
“All mariners and platforms offshore Galveston, be advised, NASA is conducting aeronautical flight tests from Galveston Island, Bolivar Peninsula to 20NM offshore. Sonic booms should be expected frequently. Sonic booms may be loud, but are not dangerous. Contact U.S. Coast Guard on VHF-FM CH 16 or NASA public affairs for questions or more information.”
The second was a Safety Marine Information Broadcast that was broadcast 10 minutes prior to the Sonic Boom testing:
“All mariners offshore Galveston, be advised, sonic boom expected within the next five to ten minutes IVO Galveston Island, Bolivar Peninsula to 20NM offshore. Sonic Boom is associated with NASA supersonic flight tests. Advise to inform crews as necessary for situational awareness. Sound may be loud, but is not dangerous.”
The Boom and the Bust of Supersonic Air Travel
The first sonic boom flight was recorded on October 14, 1947 in an X-1, flown by Chuck Yeager. Yeager is credited as being the first person to break the sound barrier in level flight, flying at an altitude of 45,000 ft. (13.7 km).
Two passenger airliners have utilized supersonic transport: the Russian Tupolev Tu-144 and the more familiar Concorde. The origins of the Concorde project dates back to the 1950s, when the Royal Aircraft Establishment formed a committee to study the supersonic transport (SST) concept. On September 26, 1973 the Concorde flew over land at supersonic speeds — the sonic boom was too loud and was prohibited from flying over land. The Concorde could cross the Atlantic in just over three hours by traveling twice the speed of sound and began making transatlantic flights. Residents complained about the sonic boom, saying it was a nuisance and a safety issue, and the FAA banned the Concorde as well as any future supersonic civil aircraft from flying over land. The Concorde stopped flying in 2003.
Clearing the Skies for Faster-Than-Sound Air Travel
NASA’s team must address two issues for supersonic travel to gain public acceptance. Sonic booms are extremely loud, disruptive, and have occasionally presented some hazards on land. Secondly, regulations continue to prohibit commercial supersonic flight over land-the next gen of supersonic jets must be seen and not heard.
To accomplish this, NASA is leading a government-industry team to collect data that could make supersonic flight over land a reality. NASA’s Low-boom mission is organized within two of the agency’s aeronautics programs: the Advanced Air Vehicles Program and the Integrated Aviation Systems Program.
The Low-boom Flight Demonstration mission has two goals: (1) design and build a piloted, large-scale supersonic X-plane with technology that reduces the loudness of a sonic boom to that of a gentle thump; and, (2) fly the X-plane over select U.S. communities to gather data on human responses to the low-boom flights and deliver that data set to U.S. and international regulators.
Using this gathered data, new sound-based rules regarding supersonic flight over land can be written and adopted, which would open the doors to new commercial cargo and passenger markets to provide faster-than-sound air travel.
Feedback from some of the 500 Galveston residents indicate the sonic booms have been on the higher end of the “perceived decibel level” scale that NASA is testing, and the sonic booms recorded on the island are similar to that of a slammed car door. These sounds may not even resemble what is emitted from the future experimental X-59 research plane currently under construction for faster and quieter travel. In 2023, NASA expects to be able to fly the X-59 over U.S. cities to collect data on how areas are impacted by the supersonic flights.
NASA and Lockheed Martin Aeronautics Company recently began manufacturing the first part of NASA’s supersonic X-59 plane. It’s the first to be built in decades and is targeted for completion by 2021. One pilot will fly the 94-foot-long, 29.5-foot-wide aircraft powered by a single jet engine. Its design research speed will be Mach 1.42, or 940 mph, flying at 55,000 feet.
The agency’s goal in building the X-59 is to show the FAA the time has arrived to develop new rules about supersonic passenger flights, which would cut cross-country, commercial flight times in half. NASA continues to make aviation history through leading the innovative project, and Galveston’s waters are playing a part in helping commercial supersonic air travel ready for take-off.
Editor note: The Texas A&M students are part of a multidisciplinary team of researchers selected by NASA to receive a five-year, $10 million grant as part of NASA Aeronautics’ University Leadership Initiative (ULI) to supplement the agency’s efforts to perfect supersonic flight.
- Date December 5, 2018
- Tags 2018 Nov