Douglas A2D Skyshark
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The Douglas A2D Skyshark is an American turboprop-powered attack aircraft built by the Douglas Aircraft Company for the United States Navy. The program was substantially delayed by engine reliability problems, and was canceled because more promising jet attack aircraft had entered development and the smaller escort carriers the A2D was intended to utilize were being phased out.
Design and developmentEdit
On 25 June 1945, the Bureau of Aeronautics (BuAer) asked Douglas Aircraft for a turboprop-driven aircraft. Three proposals were put forth in the next year and a half: the D-557A, to use two General Electric TG-100s (T31s) in wing nacelles; the D-557B, the same engine, with contra-rotating propellers; and the D-557C, to use the Westinghouse 25D. These were canceled due to engine development difficulties, but BuAer continued to seek an answer to the high fuel-consumption of jet aircraft.<ref name="Frnc Doug p472">Francillon 1988, p. 441.</ref>
On 11 June 1947 Douglas received the Navy's letter of intent for a carrier-based turboprop. The need to operate from Casablanca-class escort carriers dictated the use of a turboprop instead of jet power.<ref>Markgraf 1997, p. 18.</ref>
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While it resembled the AD Skyraider, the A2D was different in a number of unseen ways. The 5,100-equivalent shaft horsepower (3,800 kW) Allison XT40-A2 engine had more than double the horsepower of the Skyraider's R-3350. The XT40 installation on the Skyshark used contra-rotating propellers to harness all the available power. Wing root thickness decreased from 17% to 12%, while both the height of the tail and its area grew.<ref name="Frnc Doug p473">Francillon 1988, p. 442.</ref>
Engine development problems delayed the first flight until 26 May 1950, made at Edwards Air Force Base by George Jansen.<ref name="Frnc Doug p473"/>
Navy test pilot Cdr. Hugh Wood was killed attempting to land the first prototype XA2D-1, BuNo 122988, on 19 December 1950, on its 15th flight. He was unable to check the rate of descent, resulting in a high-impact crash on the runway.<ref>Heinemann and Rausa 1980, p. 180.</ref> The investigation found the starboard power section of the coupled Allison XT40A turboprop engine had failed and did not declutch. This meant the surviving engine was powering the failed engine's compressor, using up much of its available power. Additionally, the propellers failed to feather. As the wings' lift disappeared, a fatal sink rate was induced.<ref name="Wings"/>
Additional instrumentation and an automatic decoupler was added to the second prototype, but by the time it was ready to fly on 3 April 1952, sixteen months had passed, and with all-jet designs being developed, the A2D program was essentially dead. Total flight time on the lost airframe was barely 20 hours.<ref name="Wings">McCullough 1995, pp. 18–20.</ref>
Allison failed to deliver a "production" engine until 1953, and while testing an XA2D with that engine, test pilot C. G. "Doc" Livingston pulled out of a dive and was surprised by a loud noise and pitch up. His windscreen was covered with oil and the chase pilot told Livingston that the propellers were gone. The gearbox had failed, but Livingston successfully landed the airplane.<ref name=enghist>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The A4D was ready to fly by the summer of 1954, but the escort carriers were being mothballed, so time had run out for the troubled A2D program.<ref>Heinemann and Rausa 1980, p. 183.</ref>
Twelve Skysharks were built, two prototypes and ten pre-production aircraft. Most were scrapped or destroyed in accidents, and only one has survived.<ref name=goleta>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Aircraft on displayEdit
- A2D-1 Skyshark, BuNo. 125485, is at the Gillespie Field Annex of the San Diego Air & Space Museum in El Cajon, California. It was restored for static display by Pacific Fighters.<ref name=goleta/>
Specifications (A2D-1)Edit
See alsoEdit
NotesEdit
BibliographyEdit
- Template:Cite magazine
- Francillon, René J. McDonnell Douglas Aircraft Since 1920: Volume I. Annapolis, Maryland: Naval Institute Press, 1988. Template:ISBN.
- Heinemann, Edward, H. and Rausa, Rosario. Combat Aircraft Designer. London: Jane's Publishing, 1980. Template:ISBN.
- Markgraf, Gerry. Douglas Skyshark, A2D Turbo-Prop Attack (Naval Fighters No. 43). Simi Valley, CA: Ginter Books, 1997. Template:ISBN.
- McCullough, Anson. "Skyshark", Wings 25(5), October 1995, pages 18–20
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