This is a merry-go-round plane launcher. Here’s how it works.

This has got to be the greatest horrible idea in the history of aviation: merry-go-round plane launchers.

Think about it: Runways take up a lot of space. So much space that airports are often built on the outskirts of cities, far from the centers of commerce they are servicing. So why not try a circular runway instead?

Popular Mechanics explained how such an apparatus might work in its July 1941 issue.

"The device would whirl the plane around and around until it attained sufficient speed to be released into the air," the magazine reported. If all went well on release, the airplane would continue in a straight-line path tangent to the arc of the motor arm. The military could find it useful, launching heavy bombers from compact bases.

While there's no evidence (that I could find) that this death trap contraption was ever built, plans for similar machines have been circulating since the very early days of aviation.

Here's US patent No. 1,033,148: "Launching device for flying machines" (a fantastic-sounding invention if I ever heard one):

This one, patent No. 1,925,212 — from 1930 — seems extra dangerous, combining a refueling apparatus with the centrifugal carousel:

Even the US Post Office — an early adopter of aviation technology — was intrigued by the possibility of circular takeoff.

In 1918 — the year airmail routes began — a Post Office official told the New York Times the service was considering installing a merry-go-round launcher on the post office in New York City. It would only cost $50,000, and would save about an hour in travel time between New York and Washington.

(Never mind the terrifying logistics of controlling air traffic control in Midtown Manhattan. I'm assuming the post office referenced in the clip below is the the General Post Office building — now called James A. Farley Post Office Building — which was built in 1912.)

So did this ever happen?

"I wish I had better news for you but the Post Office never implemented a merry-go-round launcher," Nancy Pope, a curator at the Smithsonian's National Postal Museum, wrote me in an email. "I would imagine that a big issue would have been that in 1920 the Post Office operated the airmail service with its own airplanes, none of which were designed to be spun around." What a shame.

The Smithsonian's Air and Space Museum was similarly convinced that neither the Post Office nor any aviator had ever used such a system.

"The passengers would have been plastered to one side of the cabin and the pilots wouldn’t have known which way was up when it released," a representative from the Air and Space Museum wrote me. "In other words, a pure flight of fantasy with little real consideration."

Alas, there is at least one written account of a pilot testing out a merry-go-round launch. In 1951, a University of Wisconsin physicist named J. G. Winans wrote in Flying magazine about his successful experiment. His setup was simple: A plane was connected to a central hub like a tether ball. The takeoff was powered by the plane's engine alone.

"The acceleration toward the center of nearly one G may or may not be pleasant — depending on whether you like to ride on certain carnival devices," Winans wrote. "We mostly found it uncomfortable."

Overall, the physicist declared the contraption a plausible replacement for a runway. Circular takeoff with a 250-foot radius provided an extra "180 feet of clearance over that obtainable with a straight take-off," he reported.

His conclusion: "The evidence presented here it [merry-go-round takeoff] has great advantages under specialized circumstances."

Maybe it's time to dust off those old plans.