The Advanced Medium STOL Transport (AMST) project was intended to replace the

Lockheed C-130 Hercules The Lockheed C-130 Hercules is an American four-engine turboprop military transport aircraft designed and built by Lockheed (now Lockheed Martin). Capable of using unprepared runways for takeoffs and landings, the C-130 was originally design ...

tactical transport in

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...

service with a new aircraft with improved

STOL A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh conditio ...

performance. Increased need for strategic airlift led the Air Force to cancel the AMST program and seek a larger airlifter. Under the C-X program, the YC-15's basic design would become the successful McDonnell Douglas (later Boeing) C-17 Globemaster III.

History

The Advanced Medium STOL Transport project arose from a USAF requirement released in 1968. The official RFP was issued in 1972, asking for a C-130-class aircraft with short take-off and landing capability. This included operating from a semi-prepared field with a radius with a payload.Norton 2001, pp. 5–7. The C-130 of that era required about for this load. Five companies (

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Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...

Fairchild Fairchild may refer to: Organizations * Fairchild Aerial Surveys, operated in cooperation with a subsidiary of Fairey Aviation Company * Fairchild Camera and Instrument * List of Sherman Fairchild companies, "Fairchild" companies * Fairchild Fash ...

McDonnell Douglas McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it produ ...

and the Lockheed/

North American Rockwell North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included: the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F-8 ...

team) submitted designs at this stage of the competition. On 10 November 1972, the downselection was carried out, and

and

won development contracts for two prototypes each. This resulted in the YC-14 and YC-15, respectively.Kennedy 2004, pp. 8–11. Both the Boeing YC-14 and McDonnell-Douglas YC-15 met the specifications of the contest under most conditions. Both types had higher drag than expected, which decreased performance. In the end, it was found more economical to just continue production of the

, which the AMST might have replaced. The C-130 continues in production to this date.Norton 2001, pp. 8–11. On the Boeing YC-14, the upper-surface-blowing design for high aerodynamic lift used two jet engines that blew high-velocity airstreams over the inboard section of the wing and over special trailing-edge flaps. The large multisection flaps extended rearward and downward from the wing's trailing edge to increase the wing area, thus creating extra lift, which was further augmented by positioning the engines so their jet blast across the upper wing surfaces created still more lift. In addition, the placement of the engines above the wing prevented the engines from ingesting dirt and debris and shielded some of the engine noise from the ground so that the transport could make a quieter approach. The McDonnell Douglas YC-15 had four engines, while the Boeing version had two. The YC-15 used large double-slotted flaps that extended over 75 percent of the wingspan to enhance STOL capabilities. To save costs, it used a modified

DC-8 The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is a long-range narrow-body airliner built by the American Douglas Aircraft Company. After losing the May 1954 US Air Force tanker competition to the Boeing KC-135, Douglas announced in July ...

nosewheel unit and the

DC-10 The McDonnell Douglas DC-10 is an American trijet wide-body aircraft manufactured by McDonnell Douglas. The DC-10 was intended to succeed the DC-8 for long-range flights. It first flew on August 29, 1970; it was introduced on August 5, 1971, ...

cockpit, adapted for a two-person crew, with two lower windows for visibility during short-field landings. The increasing importance of strategic vs. tactical missions eventually led to the end of the AMST program in December 1979.Kennedy 2004, pp. 12–19. Then, in November 1979, the C-X Task Force formed to develop the required strategic aircraft with tactical capability.Kennedy 2004, pp. 19–24. The C-X program selected a proposal for an enlarged and upgraded YC-15 and one prototype (''72-1875'') was reclaimed from the

Pima Air & Space Museum The Pima Air & Space Museum, located in Tucson, Arizona, is one of the world's largest non-government funded aerospace museums. The museum features a display of nearly 300 aircraft spread out over 80 acres (320,000 m²) on a campus occ ...

refurbished and returned to

Edwards AFB Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is Ed ...

, CA for flight testing that was later incorporated into development of the

C-17 Globemaster III The McDonnell Douglas/Boeing C-17 Globemaster III is a large military transport aircraft that was developed for the United States Air Force (USAF) from the 1980s to the early 1990s by McDonnell Douglas. The C-17 carries forward the name of two ...

.Norton 2001, pp. 12–13.

References

* Kennedy, Betty R. ''Globemaster III: Acquiring the C-17'', Air Mobility Command Office of History, 2004. * Norton, Bill. ''Boeing C-17 Globemaster III'', Specialty Press, 2001. .

External links

Edwards AFB: A Pair of Most Unusual Transports
(Internet Archive)

AMST Prototypes: Boeing YC-14 and McDonnell Douglas YC-15 on theaviationzone.com

AMST vs. C-130 comparison

Boeing C-XX all-cargo carrier (concept)
{{DEFAULTSORT:Advanced Medium Stol Transport Military transport aircraft Military aircraft procurement programs of the United States Cancelled military aircraft projects of the United States