Convair R3Y Tradewind

Picture - R3Y-1 Tradewind low over San Francisco Bay near NAS Alameda

Role: transport flying boat
Manufacturer: Convair
First flight: 1954 (R3Y-1)
Introduction: 1956 (R3Y-1)
Retired: 1958
Status: Retired
Primary user: United States Navy
Number built: 11 (R3Y) & 2 (P5Y)

The Convair R3Y Tradewind was an American 1950s turboprop-powered flying boat designed and built by Convair.

Design and development

Picture - The Convair XP5Y-1 prototype in 1950. It first flew on 18 April 1950 at San Diego and crashed in 1953

Convair received a requirement from the United States Navy in 1945 for a large flying-boat using the new technology developed during the war, especially the laminar flow wing and the developing turboprop technology. Their response, the Model 117 was a large, high-wing flying boat with Allison T-40 engines driving six-bladed contra-rotating propellers, a slender high-lift wing with fixed floats, and a sleek body with a single-step hull. The Navy ordered two prototypes on 27 May 1946. Designated XP5Y-1 the first aircraft first flew on 18 April 1950 at San Diego. In August the aircraft set a turboprop endurance record of 8 hours 6 minutes. The Navy decided not to proceed with the patrol boat version but directed that the design should be developed into a passenger and cargo aircraft.

Work continued despite the loss of one of the XP5Y-1s in a non-fatal accident on 15 July 1953. The transport and cargo version was designated the R3Y-1 Tradewind and first flew on 25 February 1954. Major changes were the removal of all armament and of the tailplane dihederal, the addition of a 10ft (3.05m) port-side access hatch and redesigned engine nacelles to accept improved T40-A-10 engines. Cabin sound proofing and airconditioning were added and pressurised accommodation for 103 passengers or 24 tons of cargo. As a medivac aircraft 92 stretcher cases could be carried.

Picture - R3Y-2 variant loading a tractor

The first two built were in P5Y configuration, armed with 8,000 lb (3,600 kg) of stores (bombs, mines, depth charges, torpedoes) and 5 pairs of 20 mm cannon in fore and aft side emplacements and a tail turret. The next five were built as R3Y-1 aircraft, intended for troop transport and inflight refuelling tanker service. The final six were built as the R3Y-2 variant with a lifting nose and high cockpit (similar to modern-day eyes to the C-5 Galaxy's nose and cockpit) for heavier transport and landing-ship duties.

Eleven aircraft were built, of which six were front-loading R3Y-2 aircraft with a hinged nose and high cockpit; they were intended to be a Flying LST (landing craft). In practice, it was discovered that it was almost impossible for the pilots to hold the aircraft steady and nose on to the beach while the aircraft was loaded or unloaded. The aircraft were converted into tankers for the inflight refuelling role. They had a short service life because of the insoluble unreliability of their Allison T40 turboprop engines, a fate common to most early turboprop-powered aircraft, such as the Douglas A2D Skyshark attack aircraft.

Operational service

Picture - R3Y-2 Tradewind refuels a record four fighters in flight, 1956

The R3Y set a transcontinental seaplane record of 403 mph in 1954 by utilising the speed of high-altitude jetstream winds. This record still stands.

After service trials the aircraft were delivered to US Navy transport squadron VR-2 on 31 March 1956. Problems with the engine/propeller combination led to the ending of Tradewind operations and the unit was disbanded on 16 April 1958.

The six R3Y-2s were converted into four-point in-flight tankers using the probe-and-drogue method. In September 1956 one example was the first aircraft to successfully refuel four others simultaneously in flight in 1956, refuelling four F9F Cougars.

The program was halted after thirteen aircraft were built, the reason being the unreliability of the Allison T-40 turboprops. The crash of one of the two XP5Y-1 aircraft was judged due to catastrophic engine failure; when little progress was being made with the engine problems, the Navy halted the program. Subsequently three more aircraft were lost through engine failures, and the Navy gave up on the T-40 and aircraft powered by it. All the P5Y and R3Y aircraft were grounded in 1958 and subsequently broken up.

Variants

XP5Y-1 Prototype patrol flying boat, two built. R3Y-1 Transport aircraft for the United States Navy with side loading door, 5 built. R3Y-2 Assault transport aircraft for the USN with shorter nose incorporating an upward-opening loading door, later converted to four-point tankers for probe-and-drogue operations, six built.

Operators

United States
United States Navy

Specifications (R3Y)

Data from Steve Ginter Convair XP5Y-1 & R3Y-1/2 Tradewind

General characteristics

Crew: 5
Capacity: 80
Length: 139 ft 8 in (42.26 m)
Wingspan: 145 ft 9 in (44.42 m)
Height: 51 ft 5 in (15.68 m)
Wing area: 2,102 ft² (195.3 m²)
Empty weight: 71,824 lb (32,579 kg)
Loaded weight: 145,500 lb (66,000 kg)
Useful load: 47,951 lb (21,750 kg)
Max takeoff weight: 165,000 lb (74,800 kg)
Powerplant: 4x— Allison T40-A-10 turboprop, 5,100 hp (3,800 kW) each

Performance

Maximum speed: 337 kt (403 mph, 624 km/h)
Range: 2,420 nm (2,785 mi, 4,482 km)
Service ceiling: 39,700 ft (12,100 m)
Rate of climb: ft/min (m/s)
Wing loading: 69.22 lb/ft² (338 kg/m²)
Power/mass: 0.14 hp/lb (230 W/kg)

Bibliography

Ginter, Steve. Convair XP5Y-1 & R3Y-1/2 Tradewind. Simi Valley, CA: Ginter Books, 1996. ISBN 0-942612-34-5.

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Source: WikiPedia