On this day, 71 years ago, July 15, 1954 (June 16, 1954, the Boeing 707 prototype flew for the first time. The Boeing 707 prototype flew for the first time on July 15, 1954. Development and production of the DASH80(numbered 367-80), the prototype of the Boeing 707, began in 1952, and first flew on July 15, 1954. Soon, based on this test aircraft, the military aircraft C-135 military transport aircraft was developed for the U.S. Air Force. Later, this series of aircraft was produced in large quantities. The famous KC-135 aerial tanker was modified based on the C-315. With the consent of the U.S. Air Force, Boeing developed and developed the Boeing 707, a civilian passenger aircraft based on the C-135 in 1955. It was tested for the first time on December 20, 1957, and was officially put into use on the route in October 1958. Since then, the Boeing 707 has undergone many modifications, and the engine was replaced from the original turbojet engine to a more efficient and better performance turbofan engine. The Boeing 707 four-engine passenger plane can carry 181 passengers, has a top speed of 966 kilometers per hour, a range of 4828 kilometers, and a maximum flying altitude of 41000 feet (12,496.8 meters). The main types are 707-120,-220,-320 and-420. Civil Aviation of China purchased 10 320Cs, which were also converted into special aircraft. As of March 31, 1992, a total of 1010 707s had been ordered. The civilian Boeing 707 was discontinued in 1978, and the production line was finally closed in 1991. The last civilian 707 was delivered in March 1982. This aircraft was a 707- 320C. The last military model was delivered in May 1992. As the first truly successful jet aircraft, the Boeing 707 also has many modifications for military applications. In addition to the KC-135, military models also include the U.S. Air Force's E-3, E-6 and E-8. In addition, the past U.S. presidential plane "Air Force One" was also converted from a Boeing 707. The Boeing 707 is an important beginning of the Boeing 7 series of aircraft. It is not the first jetliner, but it is undoubtedly the first commercially successful jetliner. It dominated civil aviation services throughout the 1960s and even 1970s, and is known as the aircraft that led the world into the jet age. Picture: On December 20, 1957, the Boeing 707 jetliner completed its second flight in history in Puget Sound, Washington, USA. On that day, the aircraft made its first flight, but due to sudden weather changes, the flight was forced to be suspended after only seven minutes. After that, the sky turned clear and the aircraft made its second flight. The second flight lasted 71 minutes.