Warplanes’ biggest vulnerability is their runways. Modern airfields are no match for modern weapons; bunker-busting munitions can crater the thickest concrete.

There was a brief period after World War II when the U.S. military thought it had a solution: simply design planes that didn’t require runways!

But it really didn’t work very well.

In the late 1940s the U.S. Navy drew up plans for a so-called ”Seaplane Strike Force” consisting of float-equipped bombers, fighters and transports able to use harbors and islands as bases.

Besides the vulnerability of land bases, the concept was also motivated by the sheer size of the day’s atomic weapons, which precluded deploying them aboard aircraft carriers. But when smaller nukes and bigger carriers came along — not to mention the Polaris sub-launched ballistic missile — the seaplane armada scheme lost its luster.

But the Navy would try again to free its planes from concrete or steel airstrips, this time via a concept initially developed by its twin mortal enemies: the Nazis and the U.S. Air Force.

The Navy’s experimental Sea Dart fighter took off from the water. Navy photo

In their heyday the Nazis cranked out huff-smoking concepts for jet tail-sitters, rocket interceptors and roto-jet fighters and other no-runway warplanes — many of which never progressed past a few blueprint drawings or a plywood mock-up or two. Most of these novel plane designs threatened their pilots with extreme discomfort and spectacular deaths.

Over in the U.S. around the same time, car designer Alex Tremulis worked out a rocket fighter for the Army Air Force that looked like Captain America’s barnstormer. Meanwhile the British fielded rocket-powered catapult-launched “Hurricat” fighters off of merchant ships in a full-throated efforts at convoy defense during the Battle of the North Atlantic.

Some of these goofy ideas were pursued by the American “Pogo” and French Coléoptère projects, but as Greg Goebel of AirVectors.net notes, “[l]anding was a frightening procedure and the concept did not inspire enthusiasm.”

After the war the Air Force was keen to avoid what it considered a “nuclear Pearl Harbor,” in which its bombers and fighters might get caught on the ground during a Soviet atomic strike. The B-47 Stratojet, America’s first jet-powered nuclear bomber, used small solid-fuel ignition packs to get its engines quickly spun up and fuselage-mounted rockets to hurl its bulk into the air using as little runway as possible.

If small strap-on rockets could shorten launch distances, bigger rockets might hurl a plane into the sky with a takeoff run of zero feet — or so the Air Force believed despite the idea’s poor reception during World War II. Goebel gives an excellent account of the USAF’s “Zero-Length Launch” concept and the Soviets’ counterpart efforts.

Submarine aircraft carrier concept. Via Scott Lowther

Using then-state-of-the-art missile technology, manned jet fighters could indeed be fired into the air from the back of truck beds. Such aircraft could be rapidly deployed from hardened shelters aboard their mobile launchers, dispersed about the countryside and hurled forth into combat on plumes of rocket fire.

The takeoffs were the easy part. Test pilots described the uncanny experience of smoothly surging into the air from atop a rail then simply taking over the controls. During one test an F-104 pilot performed a barrel roll after separating from his booster.

But landing without a runway was more challenging, and here creativity ran up against physics. Goodyear made a giant airbag — no, seriously — to catch the falling jet plane safely. It didn’t work. Later the Air Force gave up on saving the plane and pilots would be told to simply bail out over friendly territory.

The Air Force eventually abandoned Zero-Length Launch, but the Navy considered giving it another go. In 1958 Boeing proposed a submarine aircraft carrier to the Navy that relied on ZLL to hurl its aircraft into the sky. The planes would have been launched from the sub’s deck while the vessel was surfaced and would have landed … somewhere else. But no one ever figured out where, exactly, so the submarine carrier never got built.

The biggest drawback of the whole Zero-Length Launch concept was its one-way nature. For all the promise of warplanes freed from vulnerable runways, the Americans never could get comfortable with simply throwing away aircraft and their crews.

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