The Douglas B-23 Dragon is an American twin-engined bomber developed by the Douglas Aircraft Company as a successor to (and a refinement of) the B-18 Bolo. Design and development Douglas proposed a number of modifications designed to improve the performance of the B-18. Initially considered a redesign, the XB-22 featured 1,600 hp Wright R-2600-1 Twin Cyclone radial engines. The complete B-18 redesign was considered promising enough by the USAAC to alter the original contract to produce the last 38 B-18As ordered under Contract AC9977 as the B-23. The design incorporated a larger wingspan with a wing design very similar to that of the DC-3, a fully retractable undercarriage, and improved defensive armament. The B-23 was the first operational American bomber equipped with a glazed tail gun position. The tail gun was a .50 calibre (12.7 mm) machine gun, which was fired from the prone position by a gunner using a telescopic sight. The first B-23 flew on July 27, 1939 with the production series of 38 B-23s manufactured between July 1939 and September 1940. Operational history While significantly faster and better armed than the B-18, the B-23 was not comparable to newer medium bombers like the North American B-25 Mitchell and Martin B-26 Marauder. For this reason, the 38 B-23s built were never used in combat overseas, although for a brief period they were employed as patrol aircraft stationed on the west coast of the United States. The B-23s were primarily relegated to training duties, although 18 of them were later converted as transports and redesignated UC-67. The B-23 also served as a testbed for new engines and systems. For example, one was used for turbosupercharger development by General Electric at Schenectady, New York. Another was used for testing cabin pressurization. After World War II, many examples were used as executive transports, with appropriate internal modifications, and as a result a large number have survived, both in public and private collections. Howard Hughes (among others) used converted B-23s as personal aircraft. Operators United States Army Air Corps Variants B-23 Twin-engined bomber version of the B-18 with modified fuselage, 38 built. C-67 Conversion to utility transport with provision for glider towing, 12 conversions from B-23, redesignated UC-67 in 1943. UC-67 C-67 redesignated in 1943. Surviving aircraft Ecuador UC-67 39-031 (HC-APV) - Ecuadorian Air Museum, Quito. United States On display B-23 39-0036 - McChord Air Museum in McChord AFB, Washington. 39-0051 -