Kaman HH-43

Kaman HH-43
Type:	helicopter
Design country:	United States
Manufacturer:	Kaman Aircraft Corporation
First flight:	1951 (HTK-1) April 21, 1953 (HOK-1) March 1959 (HH-43B) August 1962 (K-1125)

The Kaman HH-43 Huskie is a short-range helicopter from the US manufacturer Kaman Aircraft Corporation , which was primarily used for accident rescue operations and for fire fighting.

history

precursor

The first helicopter built by Kaman (K-125) had its maiden flight in January 1947 and already used the Flettner double rotor principle used in the Huskie variants . For Kaman, the K-125 formed the basis for all other designs in the 1950s and 1960s. Kaman probably knew the Flettner double-rotor drive system through contact with Richard Prewitt, who, on behalf of the American government, found out about the status of developments in helicopter construction in Germany before the Second World War. Kaman and Anton Flettner met occasionally in the USA after 1947, but there was never any technical collaboration. Flettner founded his own company in 1949 together with Charles E. Rosendahl, in which he primarily dealt with convertible aircraft concepts.

Starts as a training helicopter HTK-1

The US Marine Corps wrote out an observation helicopter ( HO mission identification ) in 1949 , which should also serve as a rescue and transport helicopter. Kaman's proposal lost to Sikorsky's S-52 (US Marine Corps designation HO5S-1), but the US Navy ordered four HOK- 1s as "reinsurance" in the event of the S-52 failing. The Kaman plant, which was in economic difficulties, needed an interim order to survive until the delivery of this new model and therefore received an order from the Navy in September 1950 for the model K-240 (US Navy designation HTK-1 , factory designation K- 240), which largely represented a Kaman K-225 with a fuselage fairing .

The first HTK-1 was completed and delivered in April 1951 and another 29 machines between November 1951 and October 1953. However, the introduction to squadrons of the US Navy Training Command did not begin until January 1953 with the introduction to the Utility Squadron HU-2 on NAS Lakehurst . The HU-1 and HU-2, deployed on April 1, 1948, were the first two helicopter squadrons of the US Navy. In addition to training, the HTK were also used for general transport tasks. After a fatal accident in 1954, thorough aerodynamic improvements were seen as absolutely necessary. After that, the model was considered so easy to fly that it was viewed as a training machine of limited use for the much more complex “conventional” emergency planes equipped with tail rotors.

Before being used for training purposes in Pensacola, Florida, the three-seat HTK was used for a variety of other tasks. This included assignments in the Philippines and Okinawa, where they played an important role in the development of composite coatings for the wooden rotor blades suitable for the tropics. The Navy also used the machine in the Arctic. HU-2 put its last copies out of service in November 1955, but the school machines were still in use until 1957.

In 1956 the US Army evaluated an HTK-1 (USAF serial no. 50-1271) under the designation H-22 as part of a broad test program with various rotary wing aircraft. However, the tests were terminated after such a short time that not even a photo of the machine was known.

A development variant of the HTK was equipped with two Boeing 502-2 shaft turbines and was thus in March 1954 the world's first two-turbine helicopter (with a drive from two gas turbines). In 1957, an HTK ( Yellow Peril , BuNo 129344) was the first remote-controlled Kaman helicopter to be tested within a joint Army / Navy program and the starting point for a long series of other drone helicopters manufactured by Kaman.

HOK and HUK for Navy and Marine Corps

In 1953, Kaman moved to the new plant in Bloomfield, Connecticut , built by the US Navy and made available to Kaman , to build the HOK (plant designation K-600) for the US Marine Corps and the HUK for the US Navy . The HOK-1 had its maiden flight on April 21, 1953. The introduction to the fleet was delayed as a result of two fatal accidents in 1954 and 1955, so that the first operational machine was only delivered to the VMO-1 observation squadron on Marine Air in April 1956 Corps Station New River (North Carolina) could be delivered. In addition to the two prototypes, 81 series machines of the HOK-1 were produced for the US Marine Corps between 1953 and 1957. The production of the HUK-1 for the US Navy amounted to 24 copies, which were built between 1953 and 1958.

At low altitudes, the HOK-1 with a flight mass of 3084 kg was able to transport two stretchers and a medical attendant on top of each other next to the pilot. The first examples used the Continental R-975 radial engine derived from a tank engine, throttled from 600 to 450 hp , as it was also used in the Piasecki HUP -1. Although the maximum speed achieved with this was only 167 km / h, the climb rate of 31 m / min at an altitude of almost 6000 m was significantly better than that of other contemporary helicopters.

The Navy Squadron UH-2 received its first HUK-1 in 1958, while the HOK-1 was used in composite squadrons of the USMC on various ships. The last machines were still in use on the VMO-2 unit until 1965.

H-43A - Huskies for the Air Force

In 1956, the US Air Force put out a competition to acquire a helicopter for use in accident rescue in the vicinity of airfields. Kaman received a contract for the construction of 18 H-43A (factory designation K-600) from 1958. These corresponded essentially, including the engine used, to the previous HOK and HUK versions. The delivery of the last H-43A in July 1959 ended the production of piston engine-powered helicopters at Kaman. The H-43A were stationed on bases of the Tactical Air Command , where they were used for short-term alarms to rescue crews and to fight fires in the event of accidents. Firefighting included the delivery of equipment and the protection of fire fighters and injured persons by hovering over the scene of the accident to keep the fire away from them.

H-43B and HH-43F - Huskies with gas turbine

Kaman HH-43F Huskie in the helicopter museum Bückeburg

The next version was the Lycoming T53 -L-1A (later -1B) shaft turbine with an 860 HP (641 kW) output and correspondingly redesigned H-43B Huskie II (factory designation K-600-3). To test the drive, which was new at the time, Kaman equipped a HOK with a Lycoming XT-53 in advance in September 1956. The first of the 175 H-43B flew in March 1959.

With the introduction of a common designation system for Air Force, Navy and Marine Corps in 1962, the H-43A and H-43B became the HH-43A and HH-43B, with the additional code letter "H" standing for "search and rescue" . The increasingly intense fighting in Southeast Asia prompted the US Air Force to order the HH-43F variant (factory designation K-600-5), which was equipped with fuselage armor, a self-sealing tank , machine gun holding devices and the more powerful T-53-L11A engine. The Air Force received the first two of a total of 37 HH-43Fs in September 1964. Series production continued until 1968.

The Air Rescue Service's HH-43B were stationed on most US Air Force bases around the world. In June 1964, the first two machines moved to the Nakon Phanom airfield of the Royal Thai Air Force to ensure SAR coverage for American operations over Laos. The increase in the number of missions led to the huskies being further involved in the Combat SAR tasks in Southeast Asia. Until the arrival of the first Sikorsky CH / HH-3 , the HH-43B were the only helicopters available for these missions. In order to increase the huskie's actually inadequate operational radius (around 220 km for the HH-43F), separate fuel depots were set up on the secretly laid out airfields in Laos. Six HH-43B were brought up to the standard of the "F" variant on site. The losses in the rescue missions were high, as there was no space in the fuselage for a special machine gunner. Only with the use of the air-refuelable Sikorsky HH-3 and Sikorsky HH-53 could the operations of the HH-43 be limited to the area in the immediate vicinity of the airfields. In this role, too, they were eventually replaced by Bell Huey . Surprisingly, during the entire working life of the huskie, no accident should be attributed to a failure of the machine itself.

As a single example, the US Navy used the QH-43G as a remote-controlled variant from the ground, from the USS Wright to enable communication with submerged submarines using a 3000 m long antenna wire . However, this TACAMO task was ultimately taken over by EC-130 aircraft.

K-1125 Huskie III

The last Huskie development version was the K-1125, which was only built once and financed by Kaman, which was initially equipped with two Boeing YT-60-BO-10 shaft turbines and later with Pratt & Whitney PT6B . The enlarged fuselage provided space for 12 people, with 85% of the components matching those of the HH-43B. A new development was the tail unit, which now consisted of a single boom with conventional tail unit surfaces. The first flight took place in August 1962. However, neither civil nor military orders were received for this further development, so that further development was discontinued.

Users

In addition to the USAF, the US Navy and the US Marine Corps, several other air forces also used the machine. In 1962 Thailand received three HH-43Bs, Burma used 12, Colombia six, Morocco four and Pakistan six. The Imperial Iranian Air Force deployed 17 HH-43Fs, in 1967 in one case 20 people were transported instead of the planned 10 and rescued from a mountain.

Some HH-43B found their way into the commercial wood industry, where the machines could be used advantageously for tree felling work due to their high lifting capacity and the relatively low noise generated by the Flettner rotors. Until the late 1990s, Kaman still used two of these machines to train future K-MAX crews.

construction

The HH-43 has counter-rotating and intermeshing double rotors with servo flaps for control according to the Flettner principle. The rotor blades are only attached to the hub with swivel joints . The servo flaps suppress the change in the angle of attack ( pitch ) and thus also make the corresponding bearings superfluous. The movement of the servo flaps turns the rotor blade and the natural resilience of the blade material ensures the deflection required for control. The two rotors can be placed in parallel for stowage purposes, but cannot be folded.

Compared to the original HH-43A, the HH-43B / F variants have twice the cabin capacity and payload. The additional space resulted from the installation of the gas turbine above the cabin between the rotor pylons, while the original radial engine was located in the rear fuselage area. By relocating the engine, it was possible to use rear folding doors.

variants

HTK-1 (from 1962 TH-43E)

first version, differs significantly in size and drive from the other Huskie variants

HH-43A (until 1962 H-43A)

USAF version of the HOK-1, 18 copies built

HH-43B (K-600-3, ex H-43B)

first series version, 200 copies

UH-43C (ex HUK-1)

OH-43D (ex HOK-1)

TH-43E (ex HTK-1)

HH-43F (K-600-5)

42 to the USAF, ten of which were diverted to the Iranian Air Force. Many HH-43B have been upgraded to the HH-43F standard.

QH-43G

an OH-43D converted as a drone for the US Navy

production

As part of the Mutual Defense Aid Program (MDAP), the Kaman 255 was also delivered to allied countries.

Approval of the Kaman 225 by the USAF, US Army and the US Navy / Marine-Corps / Coast Guard (only until 1957):

version	1950	1951	1952	1953	1954	1955	1956	1957	1958	1959	1960	1961	1962	1963	1964	1965	1966	1967	1968	TOTAL
K-225	1																			1
HOK-1 US Navy				7th	10	11	28	25th												81
HTK-1 US Navy		1	13	15th																29
H-43A									2	16										18th
H-43B										12	57	42	27	37						175
H-43B MDAP													15th	3	14th		1			33
HH-43F MDAP															3	9	6th		6th	24
HH-43F US Army															7th	11				18th
TOTAL	1	1	13	22nd	10	11	28	25th	2	28	57	42	42	40	24	20th	7th	0	6th	379

Technical specifications

Parameter	TH-43E (HTK-1)	HH-43F
crew	2-3	2 or 1 + medical supervisor
Passengers	-	10 or 4 patients on couches
Hull length	6.28 m	7.67 m
Max. Cabin width inside		1.60 m
Max. Cabin height inside		1.17 m
Wingspan of the tail unit	2.44 m	4.52 m
Height to the tip of the hub	3.79 m	3.84 m
Rotor diameter (each)	12.20 m	14.33 m
Total rotor circle	13.67 m
Max. Payload	? kg	1800 kg
Empty mass	? kg	2095 kg
Max. Takeoff mass	1135 kg	4150 kg (normal: 2950 kg)
Cruising speed	113 km / h
Top speed	? km / h	193 km / h at sea level
Service ceiling	3050 m	7010 m
Floating height with ground effect		6100 m
Floating height outside of the ground effect		4880 m
Range	312 km	810 km (at an altitude of 1500 m, 3750 kg TOW, no external loads)
Engines	a Lycoming O-435 boxer engine with 235 hp	a Lycoming T53 -L-11A shaft turbine with 1150 WPS, throttled to 825 WPS

See also

• List of aircraft types

literature

• Howard Levy: Kaman Helicopters (Database) . In: Airplane Monthly, June 2006, pp. 61–75
• Frank Colucci: Kaman's' copters . In: AIR International, April 1996, pp. 221-229
• Leonard Bridgman (ed.): Jane's All The World's Aircraft - 1959-60 , Sampson Low, Marston & Company Ltd., London, 1959, pp. 321 f.
• John WR Taylor (Ed.): Jane's All The World's Aircraft - 1965-66 , Sampson Low, Marston & Company Ltd., London, 1965, pp. 249 f.

Web links

Commons : Kaman HH-43 Huskie  - Collection of pictures, videos and audio files

• HTK-1K, the first unmanned helicopter (youtube video)
• Photos on flickr.com
• HTK-1 at the Tillamook Air Museum
• Kaman HH-43 F Huskie in the helicopter museum Bückeburg

Individual evidence

1. ^ Kyrill von Gersdorff, Kurt Knobling: Helicopter and Gyrocopter (Die deutsche Luftfahrt Volume 3) , Bernard & Graefe Verlag, Munich, 1982, ISBN 3-7637-5273-0 , p. 97
2. ^ David A. Anderton: German Rotorcraft Pioneer Comes Back . In: Aviation Week November 29, 1954, p. 28
3. ↑ Photo of the HTK with two shaft turbines
4. ↑ Mike Tooley, Antonio Filippone, THG Megson, Michael V. Cook, PW Carpenter, EL Houghton, David Wyatt, Lloyd R. Jenkinson, Jim Marchman, Filippo De Florio, John Watkinson, Pini Gurfil, Howard D. Curtis: Aerospace Engineering Desk Reference , Verlag Butterworth-Heinemann, 2009, ISBN 9781856175760 , p. 939
5. ^ List of "Lima Site Airfields" in Laos
6. ↑ Use of the QH-43G on the USS Wasp
7. ↑ Statistical Digest of the USAF 1948 , p. 16; 1949, p. 164 f .; 1951, p. 158; 1952, p. 158; 1953, p. 185 f .; 1954, pp. 70 f .; 1955, p. 80 f .; 1956, p. 91 f .; 1957, p. 97 f .; 1958, p. 72; 1959, p. 68; 1960, p. 62; 1961, p. 70; 1962, p. 72 f .; 1963, p. 71 f .; 1964, p. 58 f .; 1965, pp. 60 f .; 1966, p. 115 f .; 1967, p. 122 f .; 1968, p. 132 f.