written by: Jason C. Chavis•edited by: Laurie Patsalides•updated: 8/25/2011
The military has the tendency to use its cargo and passenger aircraft for long periods of time. However, by the 1990s, it was apparent that its previous workhorse, the C-9 Skytrain II, was in need of replacement. Enter the Boeing 737 as the Clipper.
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Creation of the Boeing 737
C-40 aircraft history began with the creation of a passenger vehicle in the second half of the 20th century. In an effort to supplement its 727 model, Boeing began designing the basic structure of the 737 in 1964. The general concept of the model was to house 50 to 60 passengers for short to mid-range routes up to 1,000 miles (1,600 km). The following year, the 737 was launched, however, the passenger count was expanded to 100.
Over the years, Boeing made many modifications to the original design, expanding the fuselage, increasing the fuel tank for longer distance travel and adding more powerful engines. Faced with a number of competitors of the era, interest in the Boeing design by the military was still years off. At the time, the U.S. Navy and Air Force began to purchase the McDonnell Douglas DC-9 for use as its C-9 Skytrain II aircraft.
Above right: C-40 Clipper. (Supplied by the U.S. Air Force; Public Domain; http://upload.wikimedia.org/wikipedia/commons/5/52/C-40B_USAF_VIP_Transport.jpg)
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Redesigning the 737 for the Military
In 1993, Boeing launched a major redesign effort for the craft in an effort to attract new customers and compete against the Airbus A319. Known as the “Next Generation", the model was dubbed the 737-700, a variant that featured an additional 16 feet (4.9 m) of wingspan and 30 percent more fuel capacity.
The other major addition to the Boeing 737 was a new engine, the CFM56-7. Quieter and more powerful than previous engines, this allowed the new design to obtain greater thrust during takeoff and travel further due to its fuel efficiency. This was one of the deciding factors that helped the military decide to implement the 737 into it's fleet. Effectively, by the late 1990s, the era of the C-40 aircraft history had begun. In 2000, the first C-40 Clipper rolled onto the tarmac of Boeing Field in Seattle, Washington.
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Types of C-40 Aircraft
The U.S. Navy uses a version of the 737-700 known as the C-40A. This modified version of the aircraft is used primarily for logistical support. Capable of housing three cargo pallets and 70 passengers aboard the flight deck, it also is fitted with a number of unique features specifically used by the Navy. It uses the Reduced Vehicle Separation Minimum, a technology that allows for closer air support than civilian models. The C-40A also has GPS, collision avoidance systems, warning systems and tactical navigation abilities.
The U.S. Air Force uses the C-40B as its primary sky office for senior commanders and various government leaders. It is capable of secure communications and data management to anywhere in the world. The C-40B is fitted with the Internet, television, fax machines and copiers.
Designed to replace its C-22 fleet, the C-40C is used by the Air National Guard primarily as a transport vehicle. Capable of carrying up to 121 passengers, the aircraft is essentially a personnel mobilizer.
Judging from the length of time the military uses its vehicles, the Clipper will most likely be part of the Navy, Air Force and Air National Guard's respective fleets for many years.
Above left: C-40A Clipper loading passengers. (Supplied by the U.S. Department of Defense; Public Domain; http://upload.wikimedia.org/wikipedia/commons/6/60/USN_C-40A_Clipper.jpg)