https://en.wikipedia.org/wiki/Convair_R3Y_Tradewind
The Convair R3Y Tradewind was an American 1950s turboprop-powered flying boat
designed and built by Convair.
Convair received a request from the United States Navy in 1945 for the design of
a large flying boat using new technology developed during World War II,
especially the laminar flow wing and still-developing turboprop technology.
Their response was the Model 117. It was a large high-wing flying boat with
Allison T-40 engines driving six-bladed contra-rotating propellers. It had a
sleek body with a single-step hull and a slender high-lift wing with fixed
floats. 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 eight hours six minutes. The Navy decided
not to proceed with the patrol boat version, instead directing that the design
should be developed into a passenger and cargo aircraft.
One of the XP5Y-1 prototypes was lost in a non-fatal accident on 15 July 1953,
while design and development continued on the passenger and cargo version of the
aircraft. 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 10 ft (3.05 m) port-side
access hatch, and redesigned engine nacelles to accept improved T40-A-10
engines. Cabin soundproofing and airconditioning were added for pressurised
accommodation for 103 passengers or 24 tons of cargo. As a medevac aircraft, 92
stretcher cases could be carried.
A total of eleven aircraft were built. The first two prototypes built were in
P5Y configuration, armed with 8,000 lb (3,600 kg) of munitions (bombs, mines,
depth charges, torpedoes) and five 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 in concept to the C-5 Galaxy's nose and cockpit) for heavier transport
and landing-ship duties.
The front-loading R3Y-2 aircraft with a hinged nose and high cockpit 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 unsolvable unreliability problems of their Allison
T40 turboprop engines, a fate common to most T40-powered aircraft, such as the
Douglas A2D Skyshark attack aircraft.
Role
transport flying boat
Manufacturer
Convair
First flight
22 February 1954 (R3Y-1)
Introduction
1956 (R3Y-1)
Retired
1958
Primary user
United States Navy
Number built
11 (R3Y) & 2 (P5Y)
The R3Y set a transcontinental seaplane record of 403 mph in 1954 by utilizing
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 Grumman 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.
Specifications (R3Y)
General characteristics
Crew: five
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)
Empty weight: 71,824 lb (32,579 kg)
Useful load: 47,951 lb (21,750 kg)
Loaded weight: 145,500 lb (66,000 kg)
Max. takeoff weight: 165,000 lb (74,800 kg)
Performance
Maximum speed: 337 kn (403 mph, 624 km/h)
Range: 2,420 nmi (2,785 mi, 4,482 km)
Service ceiling: 39,700 ft (12,100 m)
Rate of climb: ft/min (m/s)
Power/mass: 0.14 hp/lb (230 W/kg)
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