The SB-17, also known as the B-17H, was developed as a variant of the iconic B-17 Flying Fortress and was primarily designed for air-sea rescue missions, gaining the nickname “Dumbo” due to its rescue role.
Heavy bombers, specifically modified to manage the lifeboat’s external load, carried this robust airborne Lifeboat.
Intended for parachute drop during Dumbo missions, the SB-17 would drop a A-1 Rescue boat, which was aimed to land near downed airmen.
Contents
- SB-17
- A-1 Lifeboat
- SB-29 Superfortress
- Gasoline-Powered Distiller
- Gallery
SB-17
Approximately 130 B-17Gs underwent modifications for USAAF air-sea rescue missions, which included equipping them with an Airborne Lifeboat.
Twelve of these modified planes were given the new B-17H designation, and out of those, five were subsequently turned into TB-17Hs. In 1948, both the B-17H and TB-17H variants were re-designated as SB-17G.
Higgins Boat
Uffa Fox in the United Kingdom designed the first airborne lifeboat in 1943, and it was utilized starting in February of that year.
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Upon evaluation in the United States, Andrew Higgins deemed the Fox boat too fragile for emergency operations.
Thus, in November 1943, Higgins tasked his company’s engineers to create a more robust version, equipped with two air-cooled engines.
Higgins Industries, recognized for crafting landing craft (LCVP) and PT boats, produced the A-1 lifeboat.
This 27-foot (8 m), 3,300-pound (1,500 kg) airborne lifeboat, constructed from laminated mahogany and featuring 20 waterproof internal compartments, ensured it wouldn’t sink even if swamped or capsized.
Intended for deployment by modified Boeing B-17 Flying Fortresses, it was production-ready in early 1944.
The vessel, painted yellow, was stocked with enough food, water, and clothing for 12 survivors for approximately 20 days at sea.
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Its sails were deliberately kept small for ease of use by inexperienced operators. It was equipped with a “Gibson Girl” survival radio and a kite-elevated antenna.
100 to 150 Miles
The two engines propelled the boat at 8 miles per hour (13 km/h); using just one reduced the speed to 5 miles per hour (8 km/h).
It had an effective cruising range of about 1,500 miles (2,400 km), achieving 100 to 150 miles (160 to 240 km) per day.
Higgins also crafted a smaller, 18-foot (5.5 m) version of the A-1 for the US Coast Guard, which PBY Catalinas could drop. This version weighed half as much as the A-1.
Contrasting the larger USAAF version, the smaller Higgins lifeboat aimed to rescue only eight individuals or fewer.
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Though a November 1945 article in Popular Mechanics mentions it being in USCG service, the smaller version of the A-1 has few public references.
A-1 Lifeboat
The Higgins A-1 lifeboat was designed to be deployed by an SB-17, moving at an airspeed of 120 miles per hour (190 km/h) and at an altitude of approximately 1,500 feet (500 m).
The boat was to be released directly above the target requiring rescue. Initially free-falling, the boat was soon tethered by static lines connected to the aircraft’s bomb bay walkway, which deployed three 48-foot (15 m) parachutes of a standard U.S. Army design.
Descending under the parachutes, the boat adopted a 50° bow-downward angle, descending at 27 feet (8.2 m) per second, or about 18 miles per hour (29 km/h).
Similar to Fox’s airborne lifeboat, upon seawater contact, rocket-projected lines automatically extended 200 yards (180 m) to each side to assist survivors in reaching the Higgins lifeboat.
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The parachutes then acted as a sea anchor, stabilizing the boat while survivors approached.
Inside, a map providing the boat’s approximate location and a suggested compass setting for rescue would have been placed by the aircraft crew that dropped the lifeboat.
Downed P-51
The inaugural emergency use of the Higgins airborne lifeboat took place on March 31, 1945, in the North Sea, roughly 8 miles (13 km) from the Dutch island of Schiermonnikoog.
On the previous evening, a PBY Catalina landed amidst six-foot (2 m) swells to rescue a downed P-51 Mustang pilot, but a loss of oil in one of the Catalina’s engines prevented it from taking off.
The Catalina crew could not establish contact with the Mustang pilot, who was drifting in a raft, due to nightfall, distance, and limited visibility, and he was ultimately captured as a prisoner of war.
The following morning, a Vickers Warwick identified the Catalina and dropped a Fox-designed airborne lifeboat nearby.
However, after retrieval, the lifeboat began to disintegrate, repeatedly colliding with the Catalina amidst escalating sea conditions.
Destroyed
Instead, the six aircrew lashed three of their own inflatable rubber dinghies together and abandoned the aircraft in ten-foot (3 m) swells.
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Another Warwick dropped another Fox airborne lifeboat some distance away, but its parachute didn’t open and it was destroyed upon striking the water.
An SB-17 flying in the 35-mile-per-hour (56 km/h), 40 °F (4 °C) breeze dropped its load—Higgins Airborne Lifeboat No. 25—from an altitude of 1,200 feet (370 m) to land about 100 feet (30 m) from the men.
As it hit the water, one of the lifeboat’s tethering rocket lines snaked out over the junction of two of the dinghies, making an ideal shot.
The six airmen transferred to the Higgins lifeboat where they huddled down and waited for three days in the worst North Sea storm of 1945.
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Two more Fox airborne boats were dropped with gasoline and supplies on April 3, the lifeboats either swamping or breaking up upon hitting the water.
Heavy Bombing Operations
On April 4 in continuing rough seas, the airmen were picked up by two Rescue Motor Launch (RML) boats, and the Higgins A-1 lifeboat, unable to be towed, was intentionally sunk by gunfire.
In the last eight months of World War II, Dumbo operations supported simultaneous United States Army Air Forces heavy bombing operations against Japanese targets.
On any one large-scale bombing mission carried out by B-29 Superfortresses, at least three submarines were patrolling along the air route, and Dumbo aircraft sent to patrol the ocean where they searched the water’s surface and listened for emergency radio transmissions from distressed aircraft.
At the final bombing mission on August 14, 1945, 9 land-based Dumbos and 21 flying boats covered a surface and sub-surface force of 14 submarines and 5 rescue ships
Korean War
In the early 1950s, the United States Coast Guard (USCG) conducted Dumbo flights along the West Coast, utilizing the PB-1G, a variant of the B-17.
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Such an operation is briefly showcased in the 1954 film, “The High and the Mighty.” Throughout the Korean War, the USCG and the U.S. Navy jointly managed additional Dumbo missions.
The A-1 lifeboat was subsequently complemented and eventually replaced by the A-3 lifeboat, starting from 1947. The A-3 was utilized up until the mid-1950s. By that point, helicopters equipped with winches had become sufficiently prevalent, serving as a means to lift survivors directly rather than deploying a lifeboat to assist them.
SB-29 Superfortress
The primary objective of the SB-29 was to conduct air search and rescue operations for personnel marooned in the ocean.
Predominantly to facilitate rescue support for units traversing extensive distances over the vast expanses, employing radar and a disposable A-3 lifeboat.
Throughout the Korean War, SB-29s were operational, bearing A-3 lifeboats across the Yellow Sea and the Sea of Japan.
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As B-29s conducted bombing raids, the SB-29s would hold a position near the enemy shoreline, scouring for downed aircrews.
Once the stranded teams were located, the SB-29 would deploy an EDO A-3 rescue boat, which was parachuted down at a controlled descent rate to reach the crews in need.
The effectiveness of the B-17H, which was later dubbed the SB-17 Dumbo, inspired trials with a comparable air-sea rescue aircraft, modeled on the B-29, as early as 1944.
The enhanced range, augmented lift capacity, and sophisticated attributes of the Superfortress were all considered advancements over the capabilities of the SB-17.
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Starting in 1949, a sequence of conversions for a chosen group of SB-29 aircraft began. Recent investigations by Robert A. Mann indicate that primarily 25 aircraft underwent conversions, predominantly conducted at Tinker Air Force Base.
EDO A-3 lifeboat
The A-3 Airborne Lifeboat, also known as EDO Model 98, was developed by the EDO Corporation in 1947 to serve the United States Air Force, succeeding the Higgins Industries A-1 lifeboat.
With a length of 30.05 feet and a fully loaded weight of 2,736 pounds, this lifeboat had the capacity to save up to 15 survivors.
It was powered by a Meteor 20 gasoline engine, achieving speeds of 8 knots, and was deployed from the SB-29 using a 100-foot parachute.
Featuring various safety and utility elements, the A-3 lifeboat came equipped with a sail, a self-draining cockpit, and 20 watertight compartments.
It also housed bow and stern self-righting chambers that inflated automatically upon deployment, ensuring the boat could right itself.
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As it descended from altitudes between 800 and 5,000 feet, the lifeboat’s 100-foot parachute stabilized its aerial trajectory.
Metal guards shielded the boat’s propellers and rudder, and the parachute was engineered to minimize impact shock upon water entry.
Additionally, the parachute activated valves to fill self-righting chambers with carbon dioxide and turned on a white electric beacon for visibility during night operations.
Gasoline-Powered Distiller
While lacking in luxury, the A-3 lifeboat was outfitted with vital survival equipment for aircrews stranded at sea.
It boasted ladders for effortless boarding, a waterproof plexiglass casing to shield the engine, and storage spaces for warm clothing, food, medical supplies, and additional provisions for a 15-person crew.
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Moreover, the lifeboat was equipped with a gasoline-powered distiller to transform saltwater into drinking water, along with other crucial items including a sea anchor, fire extinguisher, compass, navigational aids, bilge pump, heaving quoit, tool kit, saltwater soap, and a cockpit compartment heater.
Gallery
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