The SB-29 'Super Dumbo' was a version of the B-29 adapted for air-sea rescue duty after World War II. Sixteen B-29s were modified to carry a droppable A-3 lifeboat under the fuselage; redesignated SB-29, they were used mainly as rescue support for air units that flew long distances over water. The first SB-29s were received by the Air Rescue Service in February 1947. With the exception of the forward lower gun turret, all defensive armament was retained; the aircraft additionally carried a variety of radio equipment, provisions, survival kits, and extra crew. The SB-29 was used operationally throughout the Korean War into the mid-1950s.

The first SB-29s were received by the Air Rescue Service in February 1947. They served in the Korean War where A-3 lifeboats were carried by Super Dumbos over the Yellow Sea and the Sea of Japan.

From the beginning of the Korean War, the A-3 lifeboat was kept shackled underneath an SB-29 waiting in constant readiness on the ground at each rescue airbase. Inside of the aircraft, however rainwater could enter the boat and pool within an open end of the deployment parachute's bag. After one air drop which failed because of water that had frozen at high altitude, trapping the parachute, the A-3 lifeboat was stored disconnected from the aircraft and with a rain cover in place.

Later in the Korean War, the USAF worked on improving the A-3 with a butterfly fin to stabilize the boat till the parachute opened, a full cover, enabling the drop aircraft to start the lifeboat's motor and steer it to the location of persons in the water, and other improvements. Whether any of these improved A-3s were built beyond the prototype and saw active use is unknown.
A-3 lifeboat
EDO built the lifeboat of aluminum alloy to be carried by the SB-29 Super Dumbo performing air-sea rescue duties during the Korean War. Approximately 100 of these lifeboats were built?their serial numbers began at 501 and continued in sequence.

The A-3 lifeboat was 30.05 feet (9.16 m) long and it weighed 2,736 pounds (1,241 kg) when fully loaded and ready for attachment to the aircraft. The A-3 lifeboat could rescue 15 people. It was powered by a four-cylinder four-stroke Meteor 20 gasoline engine made by the Red Wing Motor Company. With an Ailsa Craig propeller it was expected to give a speed of 8 knots (9.2 mph) under calm water conditions. Nearly 100 US gallons (380 L) of fuel were on board. The airborne lifeboat was dropped from the SB-29 on a single 100-foot (30 m) parachute. Like previous airborne lifeboat designs, it was self-righting. The boat had a boarding ladder, and carried food and water for the rescued people.

In March 1951, Time magazine reported that the USAF was testing a radio controlled steering device for the A-3 lifeboat. After the boat dropped into the sea, a radio operator aboard the rescue aircraft would start the lifeboat's engine remotely, then direct the boat toward the survivors to make it easier for them to reach. After climbing aboard, the survivors could talk to the circling aircraft by two-way radio. A gyrocompass aboard the lifeboat would be set toward the nearest safe land, and the supply of fuel would allow for 800 miles (1,300 km) of range, with further range possible if additional water, food and fuel supplies were dropped along the way. The USAF expected all their A-3 lifeboats to be equipped with radio control by early 1952.

















Specifications (B-29)
Crew: 11 (Pilot, Co-pilot, Bombardier, Flight Engineer, Navigator, Radio Operator, Radar Observer, Right Gunner, Left Gunner, Central Fire Control, Tail Gunner)
Length: 99 ft 0 in (30.18 m)
Wingspan: 141 ft 3 in (43.05 m)
Height: 27 ft 9 in (8.46 m)
Wing area: 1,736 sq ft (161.3 m2)
Aspect ratio: 11.5
Airfoil: root: Boeing 117 (22%) ; tip: Boeing 117 (9%)
Zero-lift drag coefficient: 0.0241
Frontal area: 41.16 sq ft (3.824 m2)
Empty weight: 74,500 lb (33,793 kg)
Gross weight: 120,000 lb (54,431 kg)
Max takeoff weight: 133,500 lb (60,555 kg)

135,000 lb (61,000 kg) combat overload

Powerplant: 4 ? Wright R-3350-23 Duplex-Cyclone 18-cylinder air-cooled turbosupercharged radial piston engines, 2,200 hp (1,600 kW) each
Propellers: 4-bladed constant-speed fully-feathering propellers, 16 ft 7 in (5.05 m) diameter
Performance
Maximum speed: 357 mph (575 km/h, 310 kn)
Cruise speed: 220 mph (350 km/h, 190 kn)
Stall speed: 105 mph (169 km/h, 91 kn)
Range: 3,250 mi (5,230 km, 2,820 nmi)
Ferry range: 5,600 mi (9,000 km, 4,900 nmi)
Service ceiling: 31,850 ft (9,710 m) [30]
Rate of climb: 900 ft/min (4.6 m/s)
Lift-to-drag: 16.8
Wing loading: 69.12 lb/sq ft (337.5 kg/m2)
Power/mass: 0.073 hp/lb (0.120 kW/kg)