HH-43 Huskie
HH-43B Huskie of the United States Air Force
Role Firefighting/rescue
Manufacturer Kaman Aircraft
Designer Anton Flettner
First flight 21 April 1953
Introduction November 1958
Retired Early 1970s
Status Retired
Primary users United States Air Force
United States Marine Corps
United States Navy
Number built 370[1]
Developed from Flettner Fl 282
Developed into Kaman K-1125

The Kaman HH-43 Huskie is a helicopter developed and produced by the American rotorcraft manufacturer Kaman Aircraft.[2] It is perhaps most distinctive for its use of twin intermeshing rotors, having been largely designed by the German aeronautical engineer Anton Flettner.

First flown on 21 April 1953, the HH-43 went into production and was operated by several military air services, including the United States Air Force, the United States Navy and the United States Marine Corps. 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. It was used as a search and rescue platform, having often been enhanced with makeshift modification and new apparatus to better suit the tropical conditions. The HH-43 was also exported to several other countries and sold commercially. It set several aviation records in its class, and was first helicopter to experiment with twin-turbine engines even though early designs used piston engines. By the 1970s, it was being replaced by newer rotorcraft that were typically bigger and capable of greater performance. Many of the helicopters made their way to the civilian market and museums.

Under the aircraft designation system used by the U.S. Navy pre-1962, Navy and U.S. Marine Corps versions were originally designated as the HTK, HOK or HUK, for their use as training, observation or utility aircraft, respectively. The Air Force Version was the H-43A, however after 1962 the designation system was consolidated, and that became the HH-43A, and the H-43B, the HH-43B. HUK-1 became UH-43C, HOK-1 became OH-43D, and HTK-1 became TH-43E.


HOK-1 prototype, 1953
HH-43C on sea trials in 1959

In 1947, the German aeronautical engineer Anton Flettner was brought to the United States as part of Operation Paperclip.[3] He was the developer of the two earlier synchropter designs from Germany during the Second World War: the Flettner Fl 265 which pioneered the synchropter layout, and the slightly later Flettner Fl 282 Kolibri ("Hummingbird"), intended for eventual production. Both designs used the principle of counter-rotating side-by-side intermeshing rotors, as the means to solve the problem of torque compensation, normally countered in single–rotor helicopters by a tail rotor, fenestron, NOTAR, or vented blower exhaust. Flettner remained in the United States and became the chief designer of the Kaman company.[4] In this capacity, he designed numerous new helicopters that used the Flettner double rotor.

On 21 April 1953, the first prototype, referred to by the manufacturer as the K-225, made its maiden flight. 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). During 1954, for an experiment jointly conducted by Kaman and the U.S. Navy, a single HTK-1 was modified and flown with its piston engine having been replaced by a pair of Boeing T50-BO-2 turbine engines totaling 380 hp (280 kW), becoming the world's first twin-turbine helicopter in the process.[5]

Subsequently, a much more powerful Pratt & Whitney R-1340 Wasp radial piston engine, capable of producing 600 hp (450 kW), powered for the far heavier HOK-1, HUK-1, and H-43A versions for the United States Marines, U.S. Navy, and the United States Air Force, respectively. The U.S. Air Force also opted to procure two models that were powered by a single Lycoming T53 turboshaft engine: the HH-43B with 860 hp (640 kW) and the HH-43F with 825 hp (615 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.[7]


The twin intermeshed rotors of this design
The prominent exhaust tube the turbine powered version
HOK-1 with SS-11 (M22) missiles

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?] would cause the rotors to warp and thus cause the helicopter to either rise or descend as desired.[7] The rotor blades were composed of laminated wood; these restricted the aircraft's use in heavy rains as it could cause blade delamination.[8] There was no conventional tail rotor; its absence gave the rotorcraft a somewhat unusual look.[9] The contra-rotating twin rotors posed a particular hazard on the ground; crews were instructed to avoid approaching or departing the vehicle from the sides, but to instead advance or leave the vehicle from the front, as the blades would be at their highest at this position.[10] Warnings that reinforced this instruction were usually painted on the sides of the pylons which supported the rotor heads.

The interior of the T53 turbine powered HH-43 was divided in two somewhat cramped compartments, the cockpit at the front and an aft crew compartment, which were connected by a small opening that was too narrow for most personnel to pass through (the original radial piston powered versions lacked the aft compartment).[11] Dependent on the mission being performed, the aft compartment would be used to house firefighters, medics, mechanics, and/or rescued personnel; folding sidewall-mounted seats were provided for up to four personnel in this space, while the cockpit normally housed the pilot and co-pilot alone. 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.[12]

On the exterior of the rotorcraft, a motorised hoist that was typically used for rescue missions was commonly fitted; control of the hoist was normally exercised from within the aft compartment, but the pilot could also directly control the hoist via the cyclic stick. For rescues at sea, a padded sling, nicknamed the 'horse collar', was fitted to the end of the hoist to aid in retrieval operations.[11] Due to unsatisfactory performance in the field, other devices were usually fitted, including the wire basket "Stokes litter" and a heavy "forest penetrator".[13]

Operational history

USMC HOK-1 (later renamed OH-43D) carries drums, 1956
A USAF Huskie aids a practice firefighting operation at Cam Ranh Bay Air Base, Vietnam in 1968
HH-43B on a firefighting exercise in the 1960s. The helicopter had an especially strong downwash that could blow the smoke away from the firefighters

The Huskie entered service in late 1958 with the Air Force. It was also adopted by the Navy and Marine Corp, but not the Army. It was used extensively in the Vietnam war, and was an important Search and rescue helicopter. It was also used to fight fires and for utility operations. The early rotory engine powered models gave way to turbine powered ones. It was also sold on the civilian market, and at least one warbird models are in flying condition in the 21st century.

The HH-43 Huskie was procured by the U.S. Air Force; the first H-43As were delivered to the service in November 1958 while the first H-43Bs were accepted in June 1959.[7] The U.S. Air Force primarily procured the type to perform local base rescue operations and to fight aircraft fires. For the latter capacity, the H-43 was commonly outfitted with an airborne fire suppression kit that hung beneath it; this kit, which was developed at Wright-Patterson AFB, weighed only 1,000 pounds yet could output almost 700 gallons of fire-fighting foam. Huskies were usually capable of reaching crash sites before ground vehicles could, saving often-critical time in the rescue.[7] The helicopter had an especially strong down-wash that was useful in fighting fires.[14] During 1962, the USAF opted to change the H-43 designation to HH-43 to reflect the rotorcraft's role as a rescue vehicle. The HH-43F was the last model delivered to the U.S. Air Force, these differed from earlier models primarily by engine and rotor modifications that produced greater lift.[7]

The Huskie was deployed overseas during the Vietnam War; several detachments of the Pacific Air Rescue Center, the 33d, 36th, 37th, and 38th Air Rescue Squadrons, and the 40th Aerospace Rescue and Recovery Squadron operated the type. Personnel came to commonly refer to the aircraft by its call sign "Pedro". Early on, the rotorcraft's limited range proved to be a hindrance to operations; some crews resorted to an improvised additional fuel tank housed within the aft compartment, increasing fuel capacity by roughly 75 percent.[15] During the conflict, the HH-43 flew more rescue missions than all other rotorcraft combined, largely due to its unique hovering capability; between 1966 and 1970, the type performed a total of 888 combat rescue, comprising 343 aircrew rescues and 545 non-aircrew rescues.[7] The type was also occasionally used as a firefighting vehicle in the theatre as well.[16] 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.[17][18]

Many retired Huskies were used in the logging industry until spares were difficult to get, then the price dropped and they were harder to keep in operation.[14] A HH-43 operating in the logging industry had a crash in 2006, with a failure of main gear box due to cracks.[19] The FAA said the helicopter gearbox had likely developed cracks from carrying heavy loads of logs.[19]

There is one known flying and restored Huskie by the 2020s, which is sometimes flown at the Olympia Air show.[20] There is not many spare parts available for the Huskie by this time, in particular the rotor blades.[14]


HH-43B Huskie in museum
OH-43D Huskie in 1960
HH-43F (K-600)
company designation from HTK-1/TH-43E
proposed civilian counterpart of HOK-1[21]
civilian counterpart of H-43B[21]
company designation of HOK-3 development[21]
two two-seat aircraft for evaluation
three-seat production version powered by a 240 hp (180 kW) Lycoming O-435-4 flat-six piston engine for the United States Navy,[23][24] later became TH-43E, 29 built
one example for evaluation by the United States Coast Guard
one example for static tests as a drone
prototype of United States Marine Corps version, two built
United States Marine Corps version powered by a 600 hp (450 kW) R-1340-48 Wasp radial piston engine; later became OH-43D, 81 built
proposed development powered by a Blackburn-Turbomeca Twin Turmo 600 turboshaft powerplant.[21]
United States Navy version of the HOK-1 with R-1340-52 radial piston engine; later became UH-43C, 24 built
USAF version of the HOK-1; later became the HH-43A, 18 built
post-1962 designation of the H-43A
H-43A powered by an 860 shp (640 kW) Lycoming T53-L-1B turboshaft engine, three-seats and full rescue equipment; later became HH-43B, 200-built
post-1962 designation of the H-43B
post-1962 designation of the HUK-1
post-1962 designation of the HOK-1
post-1962 designation of the HTK-1
HH-43B powered by an 825 shp (615 kW) Lycoming T53-L-11A turboshaft engine with reduced diameter rotors, 42 built and conversions from HH-43B
One OH-43D converted to drone configuration


One of 12 HH-43 Huskies acquired by the Imperial Iranian Air Force in 1965
A Thai Kaman HH.34B at the Royal Thai Air Force Museum (2014)
 United States

Surviving aircraft

In addition to those on static display and the airworthy example at the Olympic Flight Museum, many H-43s are still in use with private owners.[citation needed] While various HH-43s still exist, some models can be quite rare. For example, only of two of the 18 USAF HH-43A survived and neither is on display.[35]

A HH-43B on display at Hubschraubermuseum Bückeburg, Germany
United Kingdom
United States
Kaman HOK-1 (OH-43D) Huskie on display at Pima Air & Space Museum (March 2006)
HH-43 on display at the Museum of Aviation
HH-43B Huskie at Castle Air Museum
Side view of the same Castle Air Museum example

Specifications (HH-43F / K-600-5)

3-view line drawing of the Kaman HUK-1
3-view line drawing of the Kaman HUK-1

Data from Jane's All the World's Aircraft 1965-66,[22] National Museum of the United States Air Force : Kaman HH-43B Huskie[7]

General characteristics

12 ft 7 in (4 m) to top of rotor pylons


See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

External link



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