Boeing introduced the third member of its growing family of jet transports in July 1957 as the 717. It was orignally designed to augment the transcontinental 707-120 and the intercontinental 707-320 by filling the growing demand for an economical short-to medium-range jet airliner. When Boeing's management learned it was the risk of losing a large United Air Lines order to Convair's mid-range 880, it quickly refined the concept for the 717, renaming it the 720. With these changes - and a much lower sales price - Boeing was able to capture the United order and effectively nail the lid on the 880's coffin.
While the exterior of the new jet closely resembled the 707, Boeing made some significant modifications within. When compared to the 707-120, the 720 had a substantially lighter structure, a revised wing, less fuel capacity, and a shorter fuselage. Its lower weight and short-field capabilities allowed operations from then-exisiting runways and terminal facilities. Although completley new from a weight and structural standpoint, the 720 was intentionally designed to retain a good deal of similarity with its predecessors, allowing the use of 707 interiors, flight deck and major components. It was designed from the start to be highly cost-effective, with lower seat-mile costs. Passengers also appreciated the prestige of 707-style comfort aboard the roomy airliner.
Sixteen different airlines - and the Federal Aviation Administration - on five continents purchased a total of 154 Boeing 720s. While most airlines placed them on short-to medium-length regional routes, several operators had bigger plans. Irish International Airlines establised its firts pure-jet service with 720 trans-Atlantic flights to the United States. Lufthansa used the type on routes to Africa and South America. When hostilities prevented El Al from flying directly between Israel and South America, the 720 made the trip on a circuitous 16-hour route.
Though many were scrapped after leaving the service of the orginal owners, scores of start-up, charter and third-world airlines around the globe made use of secondhand 720s. The United States Air Force acquired several examples for spare parts to help keep its fleet of older KC-135 tankers airworthy. Because of age and attrition, flew flyable examples of the 720 survive today.
ועוד אחד
The Boeing 720, originally designated 707-020 but later changed for marketing reasons,
was a modification of the 707-120 designed for medium-range operation from shorter runways. It was lighter and faster than the Boeing 707, and had a simplified wing design. This model had relatively few sales, but was still profitable due to the minimal R&D costs associated with modifying an existing type. At one point in the promotion stage to airlines it was known as the 717. It was used before the Boeing 727 replaced it in the market.
ועוד אחד
The first commercial 707s, labeled the 707-120 series, had a larger cabin and other improvements compared to the prototype. Powered by early Pratt & Whitney turbojet engines, these initial 707s had range capability that was barely sufficient for the Atlantic Ocean. A number of variants were developed for special use, including shorter-bodied airplanes and the 720 series, which was lighter and faster with better runway performance.
ועוד אחד
The
Boeing 720 (it was called the
717 during development) was a short-lived, short-to-medium range version of the
707 that was phased out after the introduction of the
727. The 727 had half the engines which made it more economical for shorter routes.
ראשי
צ'אט
18-04-2005, 22:01
) , כמעט כל מה שאתם מחפשים נמצא ב airliners.net
מצב כלאיים
