Over 1700 of these Sikorsky helicopters were manufactured beginning in the late 1940s, serving both military and civilian use throughout the world. Sikorsky referred to this model as S-55 and the military numbered it H-19. It was also built under license in England by Westland and called the Whirlwind. The American military gave this helicopter the nickname Chickasaw.
The model is comprised of a little under 200 pieces and has a 3-blade main rotor and tail rotor that spin manually, rolling front and rear wheels, pilotís window that lifts to reveal a cockpit with instrument panel, and nose cover that lifts to reveal an engine with fan blade that spins manually. The red and white model in the splash picture above has a rescue hook and spring-loaded winch that retracts by push-button (seen next to the mini-fig standing by the door). The black model shown in pictures below has a winch that operates via a thumbwheel at the back of the fuselage below the tail.
The helicopterís contours and scale dimensions closely resemble those of the actual helicopter. When constructed, it is about 12 inches long and 5 inches high, with main rotor span of 15 inches. In the past (but not currently) I have sold on eBay a few of these helicopters as kits with printed assembly instructions.
Shown below: a mini-figure on the rescue hoist with the copter "in flight." The line retracts via a thumb-wheel behind the lower cabin. In the red-and-white version shown in the digital rendering above, there is a Lego self-winding motor (the 2x2 gray square next to the blue mini-figure) that operates the winch.
Shown below: The copter has landed, the mini-fig stands by the lower cabin entrance.
Shown below: The Sikorsky S-55 is pretty unusual in that the engine sits in front of and below the pilot's cabin! In the real aircraft, access to the engine is through a pair of gull-wing doors that have the characteristic round nose of both the S-55 and S-58 models. Here, I used a Lego half-sphere with top hinge to create the engine door. I placed an engine fan within so that there was no mistake about what surprise hides behind the door!
Shown below: The windscreen over the pilot's cabin is also a hinged Lego piece, so the pilot can be added or removed.
Photos below from the USAF and the National Museum of the Marine Corps.