A giant jet-propelled helicopter for catching rockets was once a real idea

I do love a good dose of sheer, semi-mindless audacity.

But back in 1965 the company made a proposal so bold that it bordered on insane: a giant helicopter with a rotor diameter bigger than the length of a football field, capable not merely of transporting a Saturn 5 first stage, but of actually catching it in midair as it fell on a parachute. Strike that—it did not border on insane, it was insane. But those were heady days in the mid-1960s, a time when NASA was getting nearly five percent of the federal budget—ten times more than today—and when the agency was doling out study contracts for everything from nuclear rockets to ion engines to 100-man space stations. The United States was kicking the Soviets’ asses in space. There was nothing we couldn’t do. So why should a small helicopter company that had never gained a major contract, or built a helicopter capable of carrying more than six people, think small?

It would be a monster. The rotor diameter would be over 120 meters (400 feet). Empty weight would be over 200,000 kilograms (450,000 pounds), with a useful load of nearly 250,000 kilograms (550,000 pounds)—for a gross weight of a whopping 453,000 kilograms (1,000,000 pounds).

Oh, and did we mention that this would not be any old helicopter? No, it would utilize a concept that Hiller had worked on for years and tried unsuccessfully to sell to the Army: the rotor-tip-powered lifting system. This involved putting a jet engine, or more likely two jet engines, on the tip of each of the three rotors—six jet engines in all, plus a seventh in the rear fuselage to power the tail rotor. The rotors would not have to turn very fast by helicopter standards, only about once per second. But even that would result in the advancing rotor tip approaching the speed of sound. Not only would it be big, it would be noisy. A mighty roar from a mighty monster chopper.

http://www.thespacereview.com/article/1045/1