Southern California's masters of airlift, part 3: C-15 and C-17 Globemaster III

The last post of my three-part series on the strategic airlifter dynasty produced by Douglas will focus on the last Douglas/McDonnell Douglas strategic airlifter (and by broader extension the last military aircraft to be built by the Long Beach division of Douglas/McDonnell Douglas) to be built, the C-17 Globemaster III. Today, the C-17 is part of the strategic airlift backbone of the US Air Force' Air Mobility Command (AMC), occupying a niche in strategic airlift once occupied by the Lockheed C-141 Starlifter, and it also serves the air forces of a number of US allies around the world, including the UK. However, the roots of the C-17 itself can be traced back to a short-lived effort by McDonnell Douglas to produce a jet-powered C-130 successor for the USAF, and therefore the scope of this post with respect to the C-17 Globemaster III will limit itself to the design, development, flight testing, and early deployment of the C-17 as well as the C-17's ancestor, the YC-15 prototype tactical airlifter.

McDonnell Douglas YC-15, ancestor of the C-17 Globemaster III

The long-term genesis of the C-17 begins in 1972, when the US Air Force issued a requirement for a new STOL tactical airlifter to replace the C-130 able to operate from a 2,000-foot (610 meter) semi-prepared field with a 27,000-lb (12,000 kg) payload. Five companies (Bell, Boeing, Fairchild, McDonnell Douglas, and a Lockheed/North American Rockwell team) submitted designs for the Advanced Medium STOL Transport (AMST) competition, and November 10, Boeing and McDonnell Douglas were selected to build two prototypes each for the AMST contest; the Boeing Model 953 was called YC-14 and the McDonnell Douglas design received the designation YC-15. While the YC-14 was unique in having two turbofans above the wings to create high-velocity airstreams over the inboard section of the wing and over special trailing-edge flaps for high aerodynamic lift (the so-called Coanda effect), the YC-15 layout was more conventional, with four underslung turbojets. The YC-15 made its first flight on August 26, 1975, and a total of 600 flight hours were made by the two YC-15 prototypes. Despite the YC-14 and YC-15 meeting or exceeding AMST requirements, the Air Force found that strategic airlift was of greater importance than tactical airlift, so in December 1979 the AMST program was terminated without either design having been selected for production. The first YC-15 prototype was returned to flying status by McDonnell Douglas in 1996 and flew again on April 11, 1997, being ferried to Long Beach in support of the proposed C-17B five days later. On July 11, 1998, however, the aircraft suffered a No. 1 engine failure and made an emergency landing in Palmdale, California; the USAF deemed the aircraft too expensive to repair and the first YC-15 is now on display at the Air Force Flight Test Center Museum's "Century Circle" display area at Edwards Air Force Base.

Top: Model of the C-17 Globemaster III at the Western Museum of Flight. Photographed by me on May 11, 2019.
Bottom: C-17s flying over the Blue Ridge Mountains in the eastern US in December 2005.

Shortly before the cancellation of the AMST program, in November 1979, the Air Force commenced the C-X program for a new-generation strategic airlifter combining the STOL performance of both the YC-14 and YC-15 with greater operating range. A request for proposals was issued in October 1980, and Boeing, Lockheed, and McDonnell Douglas submitted bids for the C-X context. The McDonnell Douglas design was similar to the YC-15 but had backswept wings, while the Boeing Model 1050 (internally called 'C-16') had three engines, two atop the wings as in the YC-14 and a third in the tail empennage (similar to that of the Lockheed L-1011 TriStar), and two designs offered by Lockheed were based on the C-5 and C-141. On August 28, 1981, the McDonnell Douglas design was selected as the winner of the C-X competition, receiving the designation C-17, and in December 1985, a full-scale development contract was awarded, with the USAF planning to procure 210 C-17s. However, budget constraints meant that the C-17 development program was moving at a slow pace, so the US Air Force gave the green light to a new production run of the C-5 Galaxy, modifying several C-141As to C-141B configuration, and continued purchases of the KC-10 Extender. By April 1990, the procurement for the C-17 was reduced to 120 aircraft, and on September 15, 1991 the C-17 made its first flight, later receiving the official name Globemaster III in 1993. Despite a number of problems during flight tests, including issues with wing loading, the Globemaster III was cleared for operational service in January 1995. Production of the C-17 surprisingly exceeded the originally planned procurement of 210 aircraft, with a total of 279 C-17s being manufactured until 2015 (long after McDonnell Douglas merged with Boeing in August 1997), when the last C-17 was delivered to the Air Force after Boeing shut down the Long Beach factory that Douglas and McDonnell Douglas had used to manufacture the C-74, C-124, C-133, YC-15, and C-17. Since entering service in 1995, the C-17 has seen operational deployment during a number of wars, including the 1999 Kosovo War, the War in Afghanistan, the Iraq War, the French intervention in Mali, among other conflicts. The onset of the C-17 meant that the C-141 Starlifter fleet was replaced by the Globemaster III in May 2006. Besides the US Air Force, the C-17 also serves with the Royal Air Force, Royal Canadian Air Force, Royal Australian Air Force, Indian Air Force, Kuwait Air Force, Qatari Air Force, and United Arab Emirates Air Force. 

Display model of the unbuilt C-17B tactical airlifter

In an interesting footnote, in the late 1990s, a tactical airlifter version of the C-17 was offered to the USAF as the C-17B, utilizing the STOL capability of the YC-15, and a commercial freighter variant of the C-17 was proposed for the civilian freight market as the MD-17 (later BC-17X). However, neither of these proposals progressed beyond the design phase. To this day, the USAF still uses the C-130 as its primary tactical airlifter due to the cancellation of the AMST competition and the failure of the C-17B to win military orders. The Royal Air Force, however, has gone into full bore deploying the new Airbus A400M Atlas as its primary airlifter for both strategic and tactical use after having purchased the C-17 as a backup pending the arrival of the A400M.

This post concludes my three-part overview of the airlifter dynasty developed from 1945 to 2015 by Douglas, and later McDonnell Douglas and Boeing. Throughout their operational history, the airlifters produced in the Santa Monica-Long Beach area have played a role in the mobility needs of the US Air Force and Army, including not only transporting troops and tanks to war zones abroad but also ferrying ICBMS to missile silos in the US. Although the factories that produced the C-74, C-124, C-133, YC-15, and C-17 no longer exist, Southern California was able to work in tandem with Lockheed to produce a variety of airlifter designs to create the present-day US air mobility landscape. 

References:

Cox, G., and Kaston, C., 2020. American Secret Projects 3: U.S. Airlifters Since 1962. Manchester, UK: Crécy Publishing.

Norton, B, 2001. Boeing C-17 Globemaster III. Minneapolis, Minnesota: Specialty Press. ISBN 978-1-5800-7040-9.

Norton, B, 2002.. STOL progenitors: The Technology Path to a Large STOL Transport and the C-17A. Reston, Virginia: American Institute of Aeronautics and Astronautics. ISBN 978-1-56347-576-4.