A whole series of toys were designed to be hung by a string from the ceiling for play. Some of the first aircraft toys that used this design were Zeppelins.
But, there are quite a few helicopter AND airplane toys made in this design as well.
The earliest versions use a wind-up motor to spin a propeller mounted on the tail of the aircraft. The propeller would have 2 or 3 lightweight plastic blades, often transparent in color. Once wound up, and with a little shove, this rear-mounted pusher prop causes the toy to revolve in a circle, simulating flight.
On some helicopter versions, the main rotor spins.
Still other toys have wheels that are driven by the wind-up motor as well. This feature allowed a kid to play with the toy on the floor or table more like traditional wind-ups.
I'll start the post with one of the more common helicopter examples, the "H-2 Circling Helicopter" made by Modern Toys (Masudaya) of Japan:
Interestingly, Masudaya also made this toy in an "H-1" version, but the original box seems to have stayed the same:
Note that this example has it's original string still attached.
 VX 100.JPG "EHN (Emil Hausmann) VX 100.JPG (198.56 KiB) Viewed 8515 times")
