McDonnell Douglas YC-15
YC-15 | |
---|---|
Second YC-15 prototype in flight | |
Role | Tactical airlifter
|
National origin | United States |
Manufacturer | McDonnell Douglas |
First flight | 26 August 1975 |
Status | Replaced and eventually became the C-17
|
Number built | 2 |
Developed into | Boeing C-17 Globemaster III |
The McDonnell Douglas YC-15 is a replaced prototype four-engine short take-off and landing (STOL) tactical transport. It was McDonnell Douglas' entrant into the United States Air Force's Advanced Medium STOL Transport (AMST) competition to replace the Lockheed C-130 Hercules as the USAF's standard STOL tactical transport. In the end, neither the YC-15 nor the Boeing YC-14 was ordered into production, although the YC-15's basic design would be used to form the successful McDonnell Douglas (later Boeing) C-17 Globemaster III.
Design and development
In 1968, the USAF started work on a series of prototype proposals, which would lead to both the AMST project and the
McDonnell Douglas's design incorporated a
The design team also chose to use
For later prototypes, there were several modifications including a computer on the YC-15 was devised that would calculate the best flap angle for various flight conditions given the current gross weight. Together these modifications offered a reduction in approach speed of 10 kn.[4]
For the YC-15, four engines were used, versions of the
The YC-15 interior cargo hold was large, with dimensions 47 x 11.8 x 11.4 feet.[8]
The YC-15 was the first aircraft to offer pilots a heads up display. It was especially designed to help with short field landings, showing the pilot the horizon, flight path scale, airspeed indexer and touchdown point.[9]
Operational history
Two YC-15s were built, one with a wingspan of 110 feet (34 m) (#72-1876) and one of 132 feet (40 m) (#72-1875). Both were 124 feet (38 m) long and powered by four Pratt & Whitney JT8D-17 engines, each with 15,500 pounds-force (69,000 N) of thrust.
The first flight was on 26 August 1975.[10] The second prototype followed in December. They were tested for some time at McDonnell Douglas as the Boeing entry was not ready until almost a year later. In November 1976, both designs were transferred to Edwards Air Force Base for head-to-head testing, including lifting heavy loads like tanks and artillery from dirt airfields at Graham Ranch, off the end of Runway 22.
In Phase II of the flight test program, a "refanned" Pratt & Whitney JT8D-209 was tested in No. 1 nacelle of 72–1876, and a CFM International CFM56 was tested in the No. 1 nacelle of 72–1875.[11] In addition, a new wing with increased chord and span was flown on 72–1875.[12]
The YC-15 met specifications under most, but not all, conditions. It was a very good STOL plane for its size. At a gross weight of 149,300lbs, the YC-15 flew short landing approaches at only 87 kn at a 6 degree
However, the seeds of the AMST program's demise had already been sown. In March 1976, the Air Force Chief of Staff, Gen. David C. Jones, asked the Air Force Systems Command to see if it was possible to use a single model of the AMST for both strategic and tactical airlift roles, or alternatively, if it was possible to develop non-STOL derivatives of the AMST for the strategic airlift role. This led to a series of studies that basically stated that such a modification was not easy, and would require major changes to either design to produce a much larger aircraft.
The increasing importance of the strategic vs. tactical mission eventually led to the end of the AMST program in December 1979.
After the flight test program, the two aircraft were stored at the
Specifications
Data from The Observer's Book of Aircraft.[22]
General characteristics
- Crew: 3
- Capacity: Up to 150 troops or 78,000 lb (35,000 kg) of cargo
- Length: 124 ft 3 in (37.9 m)
- Wingspan: 110 ft 3 in or 132 ft 7 in (33.6 or 40.4 m)
- Height: 43 ft 4 in (13.2 m)
- Wing area: 1,740 sq ft (160 m2)
- Empty weight: 105,000 lb (47,600 kg)
- Max takeoff weight: 216,680 lb (98,285 kg)
- Powerplant: 4 × Pratt & Whitney JT8D-17 turbofans, 16,000 lbf (71 kN) thrust each
Performance
- Maximum speed: 590 mph (950 km/h, 510 kn)
- Cruise speed: 543 mph (872 km/h, 471 kn)
- Range: 2,995 mi (4,800 km, 2,600 nmi) with a 38,000-pound (17,000 kg) payload
- Service ceiling: 30,000 ft (9,100 m)
See also
Related development
Aircraft of comparable role, configuration, and era
Related lists
References
Notes
- ^ Norton 2001, pp. 6–7.
- ^ Kennedy 2004, pp. 8–11.
- ^ "McDonnell Douglas YC-15 (Part 1)". 23 April 2013.
- ^ "McDonnell Douglas YC-15 (Part 1)". 23 April 2013.
- ^ Johnson 2013, p. 347.
- ^ The engines were the same as on the DC-9. US Air Force Flight Test Center Museum display placard for the YC-15
- ^ Norton, 2002, pp. 77–78.
- ^ "McDonnell Douglas YC-15 (Part 1)". 23 April 2013.
- ^ "McDonnell Douglas YC-15 (Part 1)". 23 April 2013.
- ^ Green 1976, p. 156.
- ^ Norton 2002, p. 100.
- ^ Norton 2002, p. 101.
- ^ "McDonnell Douglas YC-15 (Part 1)". 23 April 2013.
- ^ Kennedy 2004, pp. 12–19.
- ^ Kennedy 2004, pp. 19–24.
- ^ Norton 2001, pp. 12–13.
- ^ Norton 2002, p. 174.
- ^ Norton 2002, pp. 202–206.
- ^ "Picture of the McDonnell Douglas YC-15A aircraft." Airliners.net. Retrieved 23 August 2011.
- ^ "YC-15 moves to new home." Archived 17 March 2012 at the Wayback Machine Edwards AFB. Retrieved 23 August 2011.
- ^ Demilitarization of a YC-15, retrieved 18 December 2019
- ^ Green 1976, pp. 156–157.
Bibliography
- Green, William. The Observer's Book of Aircraft. London: Frederick Warne & Co. Ltd., 1976. ISBN 0-7232-1553-7.
- Johnson, E.R. American Military Transport Aircraft Since 1925. Jefferson, North Carolina: McFarland & Company, 2013. ISBN 978-0-7864-6269-8.
- Kennedy, Betty R. Globemaster III: Acquiring the C-17. McConnell AFB, Kansas: Air Mobility Command Office of History, 2004. ISBN 978-0-906339-07-7.
- Norton, Bill. Boeing C-17 Globemaster III. Minneapolis, Minnesota: Specialty Press, 2001. ISBN 978-1-5800-7040-9.
- Norton, Bill. STOL progenitors: The Technology Path to a Large STOL Transport and the C-17A. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2002. ISBN 978-1-56347-576-4.