Convair XP5Y-1 / R3Y Tradewind flying boat
After World War II, the Navy realized that increased performance could be attained on a flying boat that took advantage of turboprop engines and a thin-high-lift wing. Convair developed the Model 117, which had a high wing, four turboprops, and six-blade contra-rotatin propellers, for the Navy. On 27 May 1946 contract was awarded for two prototypes of Convair's proposal, which were powered by four turboprops and were designated XP5Y-1. This aircraft had an unusually thin fuselage, with a length-to-beam ratio of ten to one, and fixed stabilizing floats. Power was supplied by four Allison T40-A4 turboprops, each driving two contra-rotating propellers through a common gearbox and producing 3,806 kW (5,100 shp) and 830 lbs of jet thrust. The main role was ASW, and if it had entered service it would have been fitted with advanced radar, ECM, and MAD equipment. It could carry 3629 kg (8000 lbs) of bombs, mines, rockets, and torpedoes. It also had five pairs of 20mm guns (two on each side, fore and aft, and one behind the rudder).
On 18 April 1950, after a couple months' delay due to problems with the engines, the aircraft made its first flight from San Diego, and it set a turboprop endurance record of eight hours and six minuites in August. The range was 5521 km (3450 mi) without weapons. Also in August, the USN decided to terminate development of the XP5Y-1 for maritime patrol but continue development of the basic design for use as a cargo and passenger aircraft. One of the two XP5Y-1s crashed off San Diego on 15 July 1953, but fortunately no one was killed. The suspected cause was engine failure.
The first of five R3Y-1 Tradewind made its first flight on 25 February 1954. All armament and tailplane dihedral were deleted, a 3.05m (10ft) wide port-side cargo hatch aft of the wing was added, and the engine nacelles were redesigned to accept T40-A-10 engines. Air conditioning and cabin sound proofing were installed. Pressurized accomodation prodiveded for up to 103 passengers or 72 stretcher cases and twelve attendants in medevac congfiguration. The maximum cargo payload was 24.4 tonnes (24 tons).
On 24 February 1955, one of the five R3Y-1s set a record which still stands by flying coast-to-coast with an average speed of 639 km/h (403 mph) during delivery to the Navy Test Center at Patuxent River, Maryland, taking advantage of the jetstream. On 18 October, a 6-hour 45-minute record flight was flown between Honolulu and NAS Alameda, California, at an average speed of 579 km/h (360 mph). The US Navy squadron VR-2 received the first of its mixed fleet of R3Y-1 and R3Y-2 Tradewinds on 31 March 1956.
Six R3Y-2 assault transports were built. These featured a hinged upward-opening nose section, providing an entrance 2.03 m (6 ft 8 in) high and 2.54 m (8 ft 4 in) wide through which men and equipment could be landed directly on the beach using the built-in ramp. The first flight was on 22 December 1954. In September 1956, a tanker-equipped R3Y-2 set a record by simultaneously refueling four Grumman F9F-8 Cougars.
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