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Old 09-26-2010, 03:01 PM   #1
copeab
 
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Location: near Houston
Default [WWII] Grumman J2F Duck utility seaplane (USA)

Grumman J2F Duck
Copyright 2010 by Brandon Cope

The J2F was a floatplane used widely by the United States Navy in several roles. It was a biplane with one large central float and two underwing stabilizing floats. One distinctive feature is that the gap between the fuselage and main float was fared over, providing an enclosed section for two passengers or rescued aircrew. Because of this, some sources refer to the Duck as a flying boat rather than a floatplane. Additionally, the main landing gear retracted (via hand crank) into the sides of the main float. The Duck was a utility seaplane, used to carry small packages (such as documents) and one or two men to ships at sea, rescue downed airmen, non-strategic recon, target towing and anti-submarine patrols and could operate from aircraft carriers, water, land bases or be catapult-launched from ships. Over 630 were built, with the majority (330) the J2F-6, which was built by Columbia Aircraft Company after Grumman devoted it's assembly lines to more important types (like the F4F Wildcat).

The most famous media appearance of the Duck was in the 1971 film Murphy's War.

The J2F-6 had a crew of three: pilot (who dropped any bombs or depth charges), a navigator/radio operator and observer/gunner (who manned fired the Browning MG). The navigator/radio operator was often not included. The J2F-6 uses 30.2 gallons of aviation gas at routine usage.

Subassemblies: Waterproofed Light Fighter-Bomber chassis +3, Medium Fighter Wings with Biplane option +2, one sealed Small TD pontoon +3, two sealed Small Weapon pontoons [Body:U] +0, three retractable wheels +0.
P&P: 670-kW supercharged HP aerial gasoline engine with 670-kW prop and 195-gallon standard fuel tanks [Body] and main Pontoon; 2,000-kW batteries.
Occ: 3 CS, 2 PS Cargo: 3 Body

Armor
All: 2/3

Weaponry
Aircraft LMG/Browning M-1919 [Body:B] (750 rounds)
2325-lb depth charges [Wings:U]

Equipment
Body: Medium radio receiver and transmitter, navigation instruments, autopilot, bombsight, arrestor gear. Wings: One 325-lb hardpoint each.

Statistics
Size: 34'x39'x13'
Payload: 1.1 tons
Lwt: 3.85 tons
Volume: 312
Maint.: 54 hours
Price: $17,700

HT: 9
HP: 165 Body, 80 each Wing, 143 main Pontoon, 38 each Stabilizing Pontoon, 16 each Wheel.

aSpeed: 190
aAccel: 5
aDecel: 15
aMR: 3.5
aSR: 2
Stall: 70 mph
-2 mph per loaded hardpoint

wSpeed: 51
wAccel: 5
wDecel: 10
wMR: 0.1
wSR: 3

Draft: 1.3'
Float: 3.86 tons

Design Notes
The historical wing area of 409 sf has been used. Design speed was 165 mph and stall speed 63 mph. Weight, cost and HP of the wings and floats were divided by two, with design weight reduced by 2.6%. Performance numbers assume a crew of two and fully loaded hardpoints, but no passengers. The hardpoints were generally only loaded for ASW patrols.

Late in the war, the arrestor gear was usually removed (or simply not installed in new production aircraft) as the ability to operate from carriers was no longer needed.

Some fuel tankage was assigned to the main float. Likewise, the space for the landing gear was transferred to the main float. This still gave ample flotation rating for the three pontoons.

A radio direction finder could be installed, but not with the rear MG in place, as the antenna obstructed the gun's fire arc.

Variants
The 48 JF (1934) used a 522-kW engine. The JF-1 and JF-2 were very similar.

The J2F-1 (1936) used a 559-kW engine. 29 built.

The J2F-2 was the first armed version, with one gun in the nose and one for the observer, plus wing bomb racks. Engine improved to 589-kW. 21 built for the USMC, plus 9 of the very similar J2F-2A.

The J2F-3 (1939) was built for use by ranking naval officers and thus had more plush passenger seating. 20 built.

The J2F-4 (1939) was similar to the J2F-2. 32 built.

The J2F-5 (1941) was the first to officially be known as the Duck and the last to be manufactured by Grumman. It mounted the 633-kW engine with aSpeed 188. 144 built.*
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