Early seventies; a trial to fly an Air Portable Baily Bridge.
This was a lightweight Baily Bridge designed to be placed across a river so that vehicles could cross unhindered. It was on an 80 ft strop and had two large plywood fins attacted to one end to encourage it to fly longways. It lifted OK and at about 40 knots it turned straight and it was so long that you could see the leading end through the bubbles. When you turned it would continue flying straight and then slowly turn and formate underneath you.
Trying to place it was a disaster. As soon as it lost airspeed it started spinning. We managed to bounce it off a covenient hillock a couple of times to slow it so that we could put it down without wrecking it.
The project was abandoned. Somebody decided that an assault across a river with a helicopter hovering at 100 ft with mutiple ZSU 23-4s firing at it was likely to be unsuccessful.