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New experimental Lockheed supersonic jet starts production – WTOP

https://wtop.com/business-finance/2018/11/lockheed-supersonic-sans-the-boom-starts-production/slide/4/

The X-59 will cruise at a speed of about 940 mph and an altitude of 55,000 feet. Lockheed says it will create a sound about as loud as a car door closing, instead of a deafening sonic boom.