[2] It is perhaps most distinctive for its use of twin intermeshing rotors, having been largely designed by the German aeronautical engineer Anton Flettner.

It was primarily intended for use in aircraft firefighting and rescue in the close vicinity of air bases, but was extensively deployed during the Vietnam War.

In 1947, the German aeronautical engineer Anton Flettner was brought to the United States as part of Operation Paperclip.

It was later adopted by the United States Navy as the HTK-1, by which point it was outfitted with a single Lycoming O-435 flat-six piston engine, producing 240 hp (180 kW).

[6] The HH-43B variant established several world records for helicopters in its class during the early 1960s, including for rate of climb, altitude, and distance traveled.

Flight control on the HH-43 was primarily effected by a series of servo-flaps, or large tabs, that was located on the trailing edge of each rotor blade; the actuation of these flaps[how?]

In a typical configuration, a pair of clamshell doors would be fitted that could open up into the aft area of the rear compartment; in tropical conditions, these doors would often be removed to help cool the interior; in such a configuration, an aft net would be installed to prevent any personnel from falling out of the aircraft.

No weapons mounts were officially approved, but some improvised arrangements did see the use of a Browning Automatic Rifle at the aft ramp position.

For rescues at sea, a padded sling, nicknamed the 'horse collar', was fitted to the end of the hoist to aid in retrieval operations.

[13] Due to unsatisfactory performance in the field, other devices were usually fitted, including the wire basket "Stokes litter" and a heavy "forest penetrator".

[15] Also called a "Jungle penetrator", it had spring loaded arms and a seat, that could be ridden up or down from the helicopter with the hoist.

[7] The USAF primarily procured the type to perform local base rescue operations and to fight aircraft fires.

Huskies were usually capable of reaching crash sites before ground vehicles could, saving often-critical time in the rescue.

[17] A Huskie performed the first combat medevac in March 1965, for an airmen downed in the Vietnamese Demilitarized Zone during Operation Rolling Thunder.

[18] Noting the shortcomings of the HH-43, the procurement of newer aircraft, such as the Sikorsky CH-3C and HH-3E, was accelerated; their arrival in quantity supplanted the type and saw its being entirely replaced during the early 1970s.

[16] (See also List of aircraft losses of the Vietnam War) Pakistan procured three HH-43Bs in 1964 for Search and rescue and general support missions in its hot and multi-terrain environment.

During the 1965 Indo-Pakistani War, the Huskies were employed in logistic support missions for the Army, transporting artillery pieces and 31,000 lb (14,000 kg) of ammunition to inaccessible battlefields in the mountains of Kashmir.

[21][22] On 8 July 1976, an H-43B from PAF Base Masroor was scrambled for a rescue mission in the Arabian Sea after receiving an SOS call from an Egyptian merchant ship "Latakia".