The Ultimate Weapon: Submarine Aircraft Carriers
If submarines possessed the high vision and quick speed of aircraft, they could dramatically extend their reach. If aircraft took off and landed from underwater platforms, their staging and strikes would be stealthier and more secure.
But combining the two epoch-making weapons has proved difficult. Only one country really pulled it off—and too late to win a war. But the tremendous potential of the aircraft-sub combo may make an historic comeback thanks to drones and Special Operations Forces.
The underwater stealthiness of submarines comes with a great downside—blindness. Subs rely on a few sensors—and help from other military assets—to comprehend their environments.
By carrying and deploying a small airplane, a submarine could dramatically expand its ability to look around itself.
But even a small sub-launched plane needs a large and heavy pressure-proof hangar to ride in while the sub submerges. Early on, only the largest subs had room for such bulky hangars.
After World War I, the British replaced an M-class sub’s 12-inch gun with an aircraft hangar. The sub-carrier sank when the hangar flooded. The French “submarine cruiser” Surcouf, the largest undersea boat in the world in the 1930s, carried a small folding plane for spotting targets for its twin eight-inch guns.
A Soviet designer came up with a submersible airplane. Though never built and full of technical loose-ends, U.L. Ushakov’s 1934 design featured a thick, manta-ray-style wing and narrow fish-like body, complete with a conning tower. Ushakov did not specify how he would seal the three radial engines against saltwater.
The machine supposedly would have flown out to sea, landed on its pontoons like a normal seaplane then flooded spaces within its wings and hull to sink. Approaching its target under electrical power while submerged, the flying sub could observe using its periscope or fire its two torpedoes.
We have no idea how well Ushakov’s clever concept would have worked in combat because the Soviets never built it. But we do have a good idea of how the Japanese would have used their submarine aircraft carriers, because they almost actually used them in battle.
Adm. Isoroku Yamamoto, who led Japan’s raid on Pearl Harbor, believed Japan had to carry the war to the American mainland. Japanese subs had already launched individual aircraft over U.S. shores. Bigger submarine carriers could get past U.S. defenses to launch air strikes on strategic targets like the Panama Canal.
Yamamoto’s vision drove Japan to create the largest non-nuclear subs ever. The Sen-Toku subs carried three Seiran bombers and enough fuel to steam around the planet. Ace crews could surface, load and launch the Seirans at night in just 45 minutes.
But the emperor’s broadcast surrender decree in August 1945 stopped the five giant subs of SubRonOne from attacking the huge U.S. Navy anchorage at Ulithi Atoll. The Americans seized the Sen-Tokus, studied them and subsequently sank them to prevent the Soviets from discovering their secrets.
In the 1950s both Soviet and American engineers explored the idea of submarine aircraft carriers. Between 1958 and 1964 the U.S. Navy installed Regulus nuclear-armed cruise missiles aboard specially-equipped subs, including USS Halibut, pictured.
Regulus was essentially a drone with a three-megaton warhead and a 500-mile range. Like the Sen-Tokus, a Regulus missile sub had to surface to launch the big drones, potentially exposing it to detection.
Guided missile submarines like Halibut and later ballistic-missile boats successfully melded the undersea and aerospace realms. But they were essentially very-long-range naval artillery rather than aircraft carriers. The sub-launched missiles were one-shots, not recoverable aircraft.
The “Flying Sub”—the yellow object seen here—became one of the pop icons of the 1960s when Irwin Allen introduced the craft on his TV show Voyage to the Bottom of the Sea. Even 50 years later, the manta-shaped sub looks incredibly futuristic, but it’s possible it drew inspiration from a real concept.
In 1962, Convair pitched the Navy a submersible aircraft design. Like the Ushakov plane, the Convair design would fly to a search area then land on water and submerge to continue its mission.
Convair released some details from the study in 1965. Like the Ushakov, the High Density Seaplane had pressure-proof compartments, floodable voids and three engines with watertight doors. Also like the Ushakov, there is no sign it was ever built.