The C-140 was built to meet a US Air Force requirement for a utility transport. With swept wings and tricycle landing gear, it was used to accomplish the combat flight inspection and navigation (C-FIN) mission. The Air Force asked for industry-financed prototypes in 1956, and Lockheed's Model 1329 was the ultimate winner of the competition. The Model 1329 first flew on September 4, 1957, only 241 days after design completion. The aircraft was adopted by the Air Force in 1959, and production began in 1960. The US Air Force bought a total of 16 JetStars as C-140As and -Bs, the first of which was delivered in late 1961.
The C-140 is a light high-speed transport low wing monoplane with the sweptback wings and an arrow-shaped tail assembly. A distinguished feature of the Jetstar is the way in which the jet engines are doubled up, two to a pod, on each side of the fuselage. The prototype aircraft was equipped with two Bristol Orpheus turbojet engines. The production series version was equipped with four Pratt-Whitney engines installed in pairs on pylons along both sides of tail end of the fuselage.
Jetstars proved a success for Lockheed in the executive market following their introduction, and 162 had been built by 1973 (including 16 for the US Air Force). In that year AiResearch Aviation Company developed a conversion kit that substituted turbofans for the older turbojets, along with various aerodynamic refinements. Lockheed built these changes into its production units after 1977, and a total of 204 aircraft were ultimately built.
Five C-140As were assigned to the Air Force Communications Command for use in evaluating military navigation aids and operations. The C-140 was used by Air Force Communications Service to check navigation aids and communications at US bases around the world.
The other eleven C-140Bs were assigned to the Miltary Airlift Command for operational support airlift. A total of seven aircraft were configured with eight-passenger VIP interiors and used to transport top US Government officials. Six were flown as VC-140Bs on special government and White House airlift missions by the 89th Military Airlift Wing at Andrews AFB, Maryland. The VC-140B carried Presidents Nixon, Ford, Carter and Reagan a number of times, although it was not the primary presidental aircraft. Whenever the President was aboard, it flew under the radio call sign "Air Force One."
The first of the dedicated business jets, the Lockheed JetStar, completed its maiden flight in September 1957. Initial development of the aircraft was undertaken as a private venture. The first two prototypes were equipped with two Bristol Siddeley Orpheus turbojet engines. The aircraft was later entered in an Air Force competition for a small four-engine utility and personal transport, and in this version was equipped with four Pratt & Whitney JT-12-8 turbojet engines of 3300 pounds thrust each.
The JetStar won the Air Force competition and in that service is known as the C-140. Production of the original JetStar ended in 1973; however, an improved version known as the JetStar II, powered with four Garrett TFE 731 turbofan engines of 3700 pounds thrust each, was offered by Lockheed in 1976. Production of the type ended late in 1978, at which time a total of 160 JetStar aircraft had been built.
The JetStar, with a gross weight of 42 500 pounds, is one of the heaviest of the business jets. A typical cabin configuration accommodates 8 to 10 passengers; a range of 2415 miles is possible with a payload of 3500 pounds. Takeoff and landing field lengths are 4700 and 3550 feet, respectively. These field lengths are based on climb and descent over a 50-foot obstacle, however, and are not to be compared with the FAR field lengths given in table VII for transport aircraft. Maximum cruising speed is 567 miles per hour at 21 000 feet, which corresponds to a Mach number of 0.80.
Wing of the JetStar is characterized by a 30° sweepback angle, an aspect ratio of 5.3, and airfoil section thickness ratios that vary from 12 percent at the root to 9 percent at the tip. An instant recognition feature of the aircraft is provided by the large external fuel tank located at the midspan position of' each wing. Unlike most business jet aircraft, the high-lift system of' the JetStar is relatively complicated and consists of  a double-slotted trailing-edge flap and a leading-edge flap. Lateral control is provided by ailerons without the assistance of' spoilers, and a speed brake is located on the underside of' the fuselage. The longitudinal trim system is unusual in that the stabilizer is fixed to the fin, which pivots to change the stabilizer angle.
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