Supersonic Flight Regulations in The U.S. - The End of the Sonic Boom Ban?

Category Engineering

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NASA's Quesst mission is inching close to end the prohibition of civilian supersonic flights over land in the United States, as it intends to develop a quieter supersonic airplane for commercial operations. The blanket ban was implemented in 1973, after various research projects had the potential to soften the impact of sonic booms but were not sophisticated enough to solve the issue. With the advent of newer technologies, the agency will conduct community overflights and public surveys to change people's perception on supersonic flights without sonic booms.

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NASA is inching close to a solution that could help end the ban on all civilian supersonic flights over land in the United States. The agency's Quesst mission, which intends to develop a more silent supersonic airplane for commercial operations, is nearing its final developmental stages, the results of which will be submitted to regulators to reconsider the prohibition order.

"It’s a rule that many people today aren’t aware of, yet it’s at the heart of what our Quesst mission with its quiet supersonic X-59 airplane is all about," said Peter Coen, mission integration manager, said in a blog post. The aircraft is designed to fly Mach 1.4 with quieter booms, and the agency last December had finished the integration of its 13-foot-long engine with 22,000 pounds of thrust, sourced from General Electric Aviation.

Supersonic flight regulations differ in every country, with some countries allowing unlimited overland supersonic travel, such as Russia and China.

The development comes as April 27, 2023, marked the 50th anniversary of a federal order that prohibited non-military aircraft from flying faster than the speed of sound and carrying out commercial operations. The ban was implemented after people complained of the excessive noise pollution and vibration, especially in cities, caused by the supersonic boom that occurred as such jets broke the sound barrier.

Musician Chuck Berry reached the sound barrier in his concert in Austin, Texas, in 1958 – before NASA had even flown the X-1.

According to NASA, during the period, various research projects had the potential to soften the impact of sonic booms, but "aeronautical technology during the 1960s and early 1970s wasn’t sophisticated enough to fully solve the problem in time to prevent the rule from being enacted." .

--- How the ban came into effect? --- .

The supersonic era in the U.S. started after the XS-1 airplane broke the sound barrier in 1947, and with such experimental flights becoming common in the coming decade, the Air Force, Navy, NASA, and the Federal Aviation Administration (FAA) employed resources to study the effects of sonic booms in various conditions, and how the public in different locations reacted to such frequent disturbances.

The Concorde is the only supersonic jetliner to have entered routine commercial service.

The U.S. federal government also initiated a plan to develop a Supersonic Transport or SST. The program was initiated by President John F. Kennedy in 1963 and the proposal intended to develop a new commercial supersonic aircraft with a capacity of 300 passengers, carrying them at a pace exceeding three times the speed of sound.

In a major setback to such developments, in 1968, a supersonic flight by an F-105 Thunderchief passing 50 feet over school premises in Colorado blew out 200 windows and injured a dozen people. Public outcry in the subsequent years led to the SST program getting scrapped in 1971 and a blanket ban on civil supersonic flights over land in 1973.

Supersonic air travel is not efficient in terms of energy consumption and can often times be more expensive then subsonic flights.

--- A supersonic experience without sonic booms --- .

NASA is hoping that new standards with respect to supersonic flights will force lawmakers to reconsider the age-old ban as newer technologies can now ensure such flights without sonic booms that could affect anyone below.

"Instead of a rule-based solely on speed, we are proposing the rule be based on sound. If the sound of a supersonic flight isn’t loud enough to bother anyone below, there’s no reason why the airplane can’t be flying supersonic," said Coen.

The shock wave created by an airplane flying at supersonic speed can be heard hundreds of miles away.

NASA with its Quesst mission, is on the path of proving that the technology works, and plans to conduct community overflights and public surveys to change pepole's perception on supersonic flights. The agency is also looking to reduce the noise pollution levels, generated by the engine afterburner, to below 125 decibels, which is two thirds the sound level of a take-off from a typical commercial aircraft.

Supersonic planes generate incredibly intense magnetic fields around them due to their incredibly fast speed.

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