CH-47 Chinook

CH-47 Chinook

The Boeing CH-47 Chinook is an American twin-engine, tandem rotor heavy-lift helicopter. Its primary roles are troop movement, artillery placement and battlefield resupply. It has a wide loading ramp at the rear of the fuselage and three external-cargo hooks. With a top speed of 170 knots (196 mph, 315 km/h) the helicopter is faster than contemporary utility and attack helicopters of the 1960s. The CH-47 is among the heaviest lifting Western helicopters. Its name is from the Native American Chinook people.

The Chinook was designed and initially produced by Boeing Vertol in the early 1960s; it is now produced by Boeing Rotorcraft Systems. It is one of the few aircraft of that era – along with the fixed-wing Lockheed C-130 Hercules cargo aircraft – that remain in production and front-line service, with over 1,179 built to date. The helicopter has been sold to 16 nations with the U.S. Army and the Royal Air Force (see Boeing Chinook (UK variants)) its largest users.

Design and development

Early development

In late 1956, the United States Department of the Army announced plans to replace the Sikorsky CH-37 Mojave, which was powered by piston engines, with a new, turbine-powered helicopter.[3] Turbine engines were also a key design feature of the smaller UH-1 “Huey” utility helicopter. Following a design competition, in September 1958, a joint Army–Air Force source selection board recommended that the Army procure the Vertol medium transport helicopter. However, funding for full-scale development was not then available, and the Army vacillated on its design requirements. Some in the Army aviation corps thought that the new helicopter should be a light tactical transport aimed at taking over the missions of the old piston-engined H-21 and H-34 helicopters, and consequently capable of carrying about fifteen troops (one squad). Another faction in the Army aviation corps thought that the new helicopter should be much larger to be able to airlift a large artillery piece, and have enough internal space to carry the new MGM-31 “Pershing” Missile System.

Vertol began work on a new tandem-rotor helicopter designated Vertol Model 107 or V-107 in 1957. In June 1958, the U.S. Army awarded a contract to Vertol for the aircraft under the YHC-1A designation. The YHC-1A had a capacity for 20 troops. Three were tested by the Army for deriving engineering and operational data. However, the YHC-1A was considered by most of the Army users to be too heavy for the assault role and too light for the transport role. The decision was made to procure a heavier transport helicopter and at the same time upgrade the UH-1 “Huey” as a tactical troop transport. The YHC-1A would be improved and adopted by the Marines as the CH-46 Sea Knight in 1962. The Army then ordered the larger Model 114 under the designation HC-1B. The pre-production Boeing Vertol YCH-1B made its initial hovering flight on 21 September 1961. In 1962 the HC-1B was redesignated the CH-47A under the 1962 United States Tri-Service aircraft designation system. It was named “Chinook”, which alludes to the Chinook people of the Pacific Northwest.

The CH-47 is powered by two turboshaft engines, mounted on each side of the helicopter’s rear pylon and connected to the rotors by driveshafts. Initial models were fitted with Lycoming T-53 jet engines with a combined rating of 2,200 shaft horsepower. Subsequent versions of the Chinook were configured with improved Lycoming engines and later with General Electric turbines. The counter-rotating rotors eliminate the need for an anti-torque vertical rotor, allowing all power to be used for lift and thrust. The ability to adjust lift in either rotor makes it less sensitive to changes in the center of gravity, important for the cargo lifting role. If one engine fails, the other can drive both rotors. The “sizing” of the Chinook was directly related to the growth of the Huey and the Army’s tacticians’ insistence that initial air assaults be built around the squad. The Army pushed for both the Huey and the Chinook, and this focus was responsible for the acceleration of its air mobility effort.

Improved and later versions

Improved and more powerful versions of the CH-47 have been developed since the helicopter entered service. The U.S. Army’s first major design leap was the now-common CH-47D, which entered service in 1982. Improvements from the CH-47C included upgraded engines, composite rotor blades, a redesigned cockpit to reduce pilot workload, improved and redundant electrical systems, an advanced flight control system and improved avionics. The latest mainstream generation is the CH-47F, which features several major upgrades to reduce maintenance, digitized flight controls, and is powered by two 4,733-horsepower Honeywell engines.

Variants

HC-1B

The pre-1962 designation for Model 114 development aircraft that would be re-designated CH-47 Chinook.

CH-47A

The all-weather, medium-lift CH-47A Chinook was powered initially by Lycoming T55-L-5 engines rated at 2,200 horsepower (1,640 kW) but then replaced by the T55-L-7 rated at 2,650 hp (1,980 kW) engines or T55-L-7C engines rated at 2,850 hp (2,130 kW). The CH-47A had a maximum gross weight of 33,000 lb (15,000 kg). allowing for a maximum payload of approximately 10,000 lb (4,500 kg) Initial delivery of the CH-47A Chinook to the U.S. Army was in August 1962. A total of 349 were built.

ACH-47A

The ACH-47A was originally known as the Armed/Armored CH-47A (or A/ACH-47A). It was officially designated ACH-47A by U.S. Army Attack Cargo Helicopter and unofficially Guns A Go-Go. Four CH-47A helicopters were converted to gunships by Boeing Vertol in late 1965. Three were assigned to the 53rd Aviation Detachment in South Vietnam for testing, with the remaining one retained in the U.S. for weapons testing. By 1966, the 53rd was redesignated the 1st Aviation Detachment (Provisional) and attached to the 228th Assault Support Helicopter Battalion of the 1st Cavalry Division (Airmobile). By 1968, only one gunship remained, and logistical concerns prevented more conversions. It was returned to the United States, and the program stopped.

The ACH-47A carried five M60D 7.62 × 51 mm machine guns or M2HB .50 caliber machine guns, provided by the XM32 and XM33 armament subsystems, two M24A1 20 mm cannons, two XM159B/XM159C 19-Tube 2.75-inch (70 mm) rocket launchers or sometimes two M18/M18A1 7.62 × 51 mm gun pods, and a single M75 40 mm grenade launcher in the XM5/M5 armament subsystem (more commonly seen on the UH-1 series of helicopters). The surviving aircraft, Easy Money, has been restored and is on display at Redstone Arsenal, Alabama.

CH-47B

The CH-47B was an interim solution while Boeing worked on a more substantially improved CH-47C. CH-47B was powered by two Lycoming T55-L-7C 2,850 shp (2,130 kW) engines. It featured a blunted rear rotor pylon, redesigned asymmetrical rotor blades, and strakes along the rear ramp and fuselage to improve flying characteristics. It could be equipped with two door-mounted M60D 7.62 mm NATO machine guns on the M24 armament subsystem and a ramp-mounted M60D using the M41 armament subsystem. Some CH-47 “bombers” were equipped to drop tear gas or napalm from the rear cargo ramp onto NLF (aka Việt Cộng) bunkers. The CH-47 could be equipped with a hoist and cargo hook. The Chinook proved especially valuable in “Pipe Smoke” aircraft recovery missions. The “Hook” recovered about 12,000 aircraft valued at over $3.6 billion during the war. 108 built.

CH-47C

The CH-47C featured more powerful engines and transmissions. Three versions of the “C model” were built. The first had Lycoming T55-L-7C engines delivering 2,850 shp (2,130 kW). The “Super C” included Lycoming T55-L-11 engines delivering 3,750 shp (2,800 kW), an upgraded maximum gross weight of 46,000 lb (21,000 kg) and a pitch stability augmentation system (PSAS). Due to difficulties with the T55-L-11 engines, which were hurriedly introduced to increase payload, they were temporarily removed and the reliable Lycoming T55-L-7C’s were installed. The type was distinguishable from the standard “C” by the uprated maximum gross weight.

The type was unable to receive FAA certification to engage in civil activities due to the non-redundant hydraulic flight boost system drive. A redesign of the hydraulic boost system drive was incorporated in the succeeding CH-47D, allowing that model to achieve certification as the Boeing Model 234. A total of 233 CH-47Cs were built. Canada bought a total of eight CH-47Cs, deliveries of the type began in 1974. Receiving the Canadian designation “CH-147”, these were fitted with a power hoist above the crew door, other changes included a flight engineer station in the rear cabin, Boeing referred to the configuration as the “Super C”. The CH-47C saw wide use during the Vietnam war, eventually replacing the older H-21 Shawnee in the combat assault support role.

CH-47D

The CH-47D shares the same airframe as earlier models, the main difference being the adoption of more powerful engines. Early CH-47Ds were originally powered by two T55-L-712 engines, the most common engine is the later T55-GA-714A. With its triple-hook cargo system, the CH-47D can carry heavy payloads internally and up to 26,000 pounds (12 t) (such as 40-foot or 12-metre containers) externally. The D-model was first introduced into service in 1979. In air assault operations, it often serves as the principal mover of the 155 mm M198 howitzer, accompanying 30 rounds of ammunition and an 11-man crew. The CH-47D also has advanced avionics, such as the Global Positioning System. Nearly all US Army CH-47D were conversions from previous A, B, and C models, a total of 472 converted into D-models. The last U.S. Army D-model built was delivered to the U.S. Army Reserve, located at Fort Hood, Texas, in 2002.

The Netherlands acquired all seven of the Canadian Forces’ surviving CH-147s and upgraded them to CH-47D standard. Six more new-build CH-47Ds were delivered in 1995 for a total of 13. The Dutch CH-47D feature a number of improvements over U.S. Army CH-47Ds, including a long nose for Bendix weather radar, a “glass cockpit”, and improved T55-L-714 engines. As of 2011, the Netherlands shall upgrade 11 of these which will be updated to the CH-47F standard at a later date. As of 2011, Singapore has 18 CH-47D/SDs, which includes twelve “Super D” Chinooks, in service. In 2008, Canada purchased 6 CH-47Ds from the U.S. for the Canadian Helicopter Force Afghanistan for $252 million.

MH-47D

The MH-47D variant was developed for special forces operations and has in-flight refueling capability, a fast-rope rappelling system and other upgrades. The MH-47D was used by U.S. Army 160th Special Operations Aviation Regiment. 12 MH-47D helicopters were produced. 6 were conversions from CH-47A models and 6 were conversions from CH-47C models.

MH-47E

The MH-47E has been used by U.S. Army Special Operations. Beginning with the E-model prototype manufactured in 1991, there were a total of 26 Special Operations Aircraft produced. All aircraft were assigned to 2–160th SOAR(A) “Nightstalkers”, home based at Fort Campbell Kentucky. E models were conversions from existing CH-47C model airframes. The MH-47E has similar capabilities as the MH-47D, but includes an increased fuel capacity similar to the CH-47SD and terrain following/terrain avoidance radar.

In 1995, the Royal Air Force ordered eight Chinook HC3s, effectively a low cost version of the MH-47E for the special forces operations role. They were delivered in 2001 but never entered operational service due to technical issues with their avionics fit, unique to the HC3. In 2008, work started to downgrade the HC3s to HC2 standard, to enable them to enter service.

CH-47F

The first CH-47F, an upgraded D model, took it maiden flight in 2001; the first production rolled out on 15 June 2006 at Boeing’s facility in Ridley Park, Pennsylvania, and first flew on 23 October 2006. Upgrades included new 4,868-shaft-horsepower (3,630 kW) Honeywell engines, an upgraded airframe featuring greater single-piece construction for lower maintenance requirements. The milled construction reduces vibrations, eliminate flexing points, and reduces inspection and repair needs; it is also expected to increase service life. The CH-47F can fly at speeds of over 175 mph (282 km/h) with a payload of more than 21,000 lb (9.5 t). New avionics include a Rockwell Collins Common Avionics Architecture System (CAAS) cockpit, and BAE Systems’ Digital Advanced Flight Control System (DAFCS).

Boeing has delivered 48 F-model helicopters to the U.S. Army through August 2008; at that time Boeing announced a five-year contract with the Army, worth over $4.8 billion for 191 more, plus 24 options. In February 2007, the Netherlands became the first international customer, ordering six CH-47Fs, expanding their current fleet to 17. The Netherlands also plans to upgrade its current 11 CH-47Ds to the CH-47F configuration. On 10 August 2009, Canada signed a contract to purchase 15 CH-47Fs for delivery in 2013–14, entering service with the Royal Canadian Air Force. On 15 December 2009, Britain announced its Future Helicopter Strategy, including the purchase of 24 new CH-47Fs to be delivered from 2012. Australia ordered seven CH-47Fs in March 2010 to replace its six CH-47Ds between 2014 and 2017.

AgustaWestland also domestically assembles a variant of the CH-47F under license, the Chinook ICH-47F, for several European nations. Boeing and the US Army are planning a CH-47F Block 2 to be introduced after 2020. The Block 2 is aiming at a payload of 22,000 lb with 4,000 ft/95 °F high/hot hover performance, with an eventual increase up to 6,000 ft/95 °F, to carry the Joint Light Tactical Vehicle. It is to feature the advanced Chinook rotor blade (ACRB), derived from the canceled RAH-66 Commanche, 20 percent more powerful Honeywell T55-715 engines, and the active parallel actuator system (APAS). The APAS is to enhance the Chinook’s digital advanced flight-control system, and provide an exact torque split between the rotors for more efficient use of performance.

MH-47G

The MH-47G Special Operations Aviation (SOA) version is currently being delivered to the U.S. Army. It is similar to the MH-47E, but features a more sophisticated avionics including a digital Common Avionics Architecture System (CAAS). The CAAS is a common glass cockpit used by different helicopters such as MH-60K/Ls, CH-53E/Ks, and ARH-70As. The MH-47G also incorporates all of the new sections of the CH-47F.

The new modernization program improves MH-47D and MH-47E Special Operations Chinook helicopters to the MH-47G design specs. A total of 25 MH-47E and 11 MH-47D aircraft were upgraded by the end of 2003. In 2002 the army announced plans to expand the Special Operations Aviation Regiment. The expansion would add 12 additional MH-47G helicopters. On 10 February 2011, leaders and employees from the H-47 program gathered for a ceremony at Boeing’s helicopter facility in Ridley Park, PA, to commemorate the delivery of the final MH-47G Chinook to U.S. Army Special Operations Command. Modernization of MH-47D/E Chinooks to MH-47G standard is due for completion in 2015.

CH-47J

The CH-47J is a medium-transport helicopter for the Japan Ground Self-Defense Force (JGSDF), and the Japan Air Self-Defense Force (JASDF). The differences between the CH-47J and the CH-47D are the engine, rotor brake and avionics. To use it by the general transportation, SAR and disaster activity like U.S. forces. The CH-47JA, introduced in 1993, is a long range version of the CH-47J, fitted with enlarged fuel tank, an AAQ-16 FLIR in a turret under the nose, and a partial glass cockpit. Both versions are built under license in Japan by Kawasaki Heavy Industries, who produced 61 aircraft by April 2001.

The Japan Defense Agency ordered 54 aircraft of which 39 were for the JGSDF and 15 were for the JASDF. Boeing supplied flyable aircraft, to which Kawasaki added full avionics, interior, and final paint. The CH-47J model Chinook (N7425H) made its first flight in January 1986, and it was sent to Kawasaki in April. Boeing began delivering five CH-47J kits in September 1985 for assembly at Kawasaki.

HH-47

On 9 November 2006, the HH-47, a new variant of the Chinook based on the MH-47G, was selected by the U.S. Air Force as the winner of the Combat Search and Rescue (CSAR-X) competition. Four development HH-47s were to be built, with the first of 141 production aircraft planned to enter service in 2012. However, in February 2007 the contract award was protested and the GAO ordered the CSAR-X project to be re-bid. In February 2010, the U.S. Air Force announced plans to replace aging HH-60G helicopters. The Air Force is deferring secondary combat search and rescue requirements that called for a larger helicopter.

Specifications

Crew 3
Capacity 55
Length (rotors running)
98 ft 10 in (30.1 m)
Fuselage length (including tail rotor)
60 ft 0 in (18.3 m)
Height 8 ft 11 in (5.7 m)
Main rotor diameter 60 ft 0 in (18.3 m)
Loaded weight 26,680 lb (12,100 kg)
Maximum weight 50,000 lb (22,680 kg)
Empty weight 23,400 lb (10,185 kg)
Maximum speed (Vne)
170 knots (196 mph, 315 km/h)
Cruising speed at sea level
130 kt (149 mph, 240 km/h)
Ascent speed at sea level
1,522 ft/min (7.73 m/s)
Ceiling in service
18,500 ft (5,640 m)
Passable distance at sea level with standard reserve
400 nmi (450 mi, 741 km)
Powerplant 2 x 3,631 KW

Operators

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