The Sikorsky YR-4B "hoverfly" was the first craft to have the honor of flying combat missions for ... at the Sikorsky R-4B and some of the other little-known helicopters that laid the foundations ...

Resembling a small flying saucer, the Avrocar was only 18 feet in ... and produced 920 pounds of thrust each. These powered a 5-foot-diameter central fan, which drew air in from the top of the ...