In the early 70s of the last century, the U.S. Air Force actively explored short take-off and landing (STOL) tactical military transport aircraft, planning to develop a new transport aircraft to replace the Lockheed C-130 that began to enter service in the 50s, after the initial screening, there were two aircraft companies, McDonnell Douglas and Boeing, of which Boeing developed the YC-14.
The Air Force proposed design standards in 1972 that required a transport aircraft to take off and run at 2,000 feet (610 m) and transport a 27,000 pounds (about 12,250 kg) payload for at least 1,000 miles (about 1,610 km) without in-flight refueling, which was a demanding standard at the time, but the YC-14 still met the performance.
The YC-14 is a tactical transport aircraft with an empty weight of about 53,400 kg, a maximum take-off weight of about 113,000 kg, and a length of 4014 meters, wingspan 3932 meters, height 14At 74 meters, the aircraft adopts a supercritical high monoplane and a large-size T-shaped vertical tail design. In order to meet the requirements of the military, it used the Kangda effect, and the research and development work was partially assisted by the NASA Langley Research Center, unlike McDonnell Douglas's four-engine blowing flap design, the YC-14 was only installed with two turbofan engines, and the engine compartment was installed at a higher position on the leading edge of the wing, and the diameter of the intake tract was longer and larger to ensure sufficient airflow to the upper surface of the wing.
Incidentally, the YC-14 was designed to produce a peculiar "tornado" when its engine was turned on thrust reverser on the ground, but don't worry, the pilots said that they never inhaled any solids such as stones and caused engine damage.
YC-14 is installed with two General Electric CF6-50D turbofan engines, a single thrust of 230kN, the airflow generated by the engine is all passed through the upper surface of the wing, with the specially designed large-angle deflection trailing edge flaps, a part of the airflow along the wing surface deflection downward to produce strong thrust, greatly shorten the take-off and running distance of the aircraft.
However, it is not easy to play the Kangda effect, Boeing found in the test that the YC-14 has problems with the airflow near the wing when flying at low altitude and low speed, which seriously affects the airflow of the engine nozzle on the surface of the wing and reduces the lift of the wing. Originally, the horizontal tail of the aircraft was installed at the rear of the aircraft, but it was later changed to a T-tail because it would interfere with the air flow.
The YC-14's unique design allows it to perform very well, with an improved prototype that not only meets the 2,000-foot take-off run, but also lands at a low speed of 99 mph (159 kmh), with a maximum flight speed of 811 kmh, a cruising speed of about 760 kmh, and a maximum range of about 5,000 km. The YC-14 outperforms McDonnell Douglas competitors in terms of transport capacity and can transport a single M60 tank directly.
February ** Dynamic Incentive Program From the whole project alone, Boeing built 2 C-14 prototypes, and the tests showed that it had met and partially exceeded the requirements of the Air Force, surpassed the competitors in terms of transport capacity, and was likely to win the competition, however, the Air Force changed in 1976, and they re-discussed the idea of transport aircraft and strategic tactical airlift, which eventually led to the termination of the entire project at the end of 1979, and the Lockheed C-130, which was originally planned to be replaced, was not only not decommissioned, Instead, it continues to serve in an upgraded version.