50 Years of the Chinook

29 January 2008 (Last Updated January 29th, 2008 18:30)

David Mackay reminisces about past versions of the Chinook and its new capabilities as a new incarnation is launched.

50 Years of the Chinook

The Chinook is one of the iconic helicopters of the modern age. It is familiar all over the globe and it is hard to realise that it was first designed and operated in 1962. But today more than 15 countries use over 1,000 Chinooks, making it one of the most widely deployed transport and cargo craft of all time.

Australia's military recently welcomed the latest version of the Chinook – the CH-47F – into service. This new version is designed for greater soldier safety and marks the latest stage of a multi-success story.

"The Chinook is one of the iconic helicopters of the modern age."

The CH-47 Chinook Helicopter is a twin-engine, tandem rotor helicopter designed for transportation of cargo, troops and weapons during day and night in visual and instrument conditions.

It was produced in A, B, C and D models, first delivered to the US Army in 1961.

The aircraft fuselage is approximately 50ft long, but with a 60ft rotor span, on each rotor system, the effective length of a CH-47 (with blades turning) is approximately 100ft from the most forward point of the forward rotor to the most rearward point on the aft rotor. Is a big helicopter, the fourth-largest ever built.

Development of the medium-lift Boeing Vertol CH-47 Series Chinook began in 1956, and since then the effectiveness of the Chinook has been regularly upgraded by successive improvements, namely the CH-47A, CH-47B, CH-47C, and CH-47D.

Its primary mission is moving artillery, ammunition, personnel and supplies on the battlefield, and it also performs rescue, aeromedical, parachuting, aircraft recovery and special operations missions. The CH-47A, first used in Vietnam in 1962, was a tandem-rotor medium transport helicopter. However, the hot mountainous conditions of Vietnam limited this model's performance capabilities and identified a requirement for increased payload and better performance.

CHINOOK DEVELOPMENT

The US Army's ongoing need for improved performance led to the development of the CH-47C. This was designed to transport a 15,000lb sling load over a 30-mile radius; the C model boasted an increased gross weight to 46,000lb, increased fuel capacity, with Lycoming T55-L11 engine developing 3,750shp, and addition structural improvements.

"The Chinook fuselage is approximately 50ft long, with a 60ft rotor span."

The first C model flew in late 1967 and was the mainstay of the Chinook fleet until the advent of the CH-47D.

Production of the C model continued until 1980 with improvements such as the crash-worthy fuel system and fibreglass rotor blades being incorporated into the fleet.

During this time, the Chinook became a familiar sight with military forces and was prominent in the Falklands War in 1982. It was essential to the movement of men and materials in that conflict and managed to cram in more than 70 passengers on one notable occasion.

In March 1979, the CH-47D was rolled-out as the modernised Chinook. From 1980 until 1993, the early CH-47 models (A, B and C) were rebuilt to the CH-47D configuration. By 2005, 46% of the army's CH-47D fleet had originally been manufactured prior to 1966.

The three existing airframes were stripped-down and then rebuilt with improved systems to provide the CH-47D. Improvements included: upgraded power plant and rotor transmission, integral lubrication and cooling for the transmission system, fibreglass rotor blades, redesigned cockpit to reduce pilot workload, redundant and improved electrical system, modularised hydraulics, advanced flight control system and improved avionics.

The CH-47D is powered by two Allied Signal Engines T55-L-712 3,750shp turboshaft engines with a maximum speed of 195mph (170kt). The CH-47D carries twice the load of a CH-47A and has improved performance. It can operate at night and in nearly all weather conditions and is equipped with an air-to-air refuelling probe, as well as carrying 44 passengers.

"The CH-47F helicopter has undergone operational testing with the 101st Airborne Division at Fort Campbell, Kentucky."

THE NEW CHINOOK

The CH-47D was upgraded to the CH-47F improved cargo helicopter configuration, and was delivered in 2006. The CH-47F improvements includes: a new-machined airframe, an upgraded T55-GA-714A 4,868hp engine to restore performance capability, common avionics architecture system, and the Air Warrior, common missile warning system.

It also contains enhanced air transportability features, a digital automatic flight control system (DAFCS), and an extended-range fuel system II for self-deployment missions. All of these features make it a much safer aircraft.

The CH-47F (and Special Operations Command MH-47D/E) incorporates reliability and maintainability improvements including airframe tuning for vibration reduction, corrosion protection, digital source collectors, and an automated maintenance programme with a 400-hour phase interval. It will remain the US Army's heavy lift helicopter until at least 2025.

The CH-47F has many technologically advanced systems. It provides crews with configurable flight displays for more efficient mission performance, in addition to a communications suite for greater situational awareness.

Avionics include terrain following / avoiding radar and an integrated forward looking infrared system for nap-of-the-earth and low-level flight operations in reduced visibility conditions. The digital automatic flight control system will provide an enhanced and safer low-speed flight capability, and the airframe enhancements will yield a safer and more reliable combat system.

The CH-47F has undergone operational testing with the 101st Airborne Division at Fort Campbell, Kentucky. The pilots are impressed with its performance and chief warrant officer Andrew Sentiff and staff sgt Michael Luna, state. "This is an impressive machine; we have enjoyed its performance and look forward to using when it is deployed on combat missions."

CHINOOKS IN ACTION

During Operation Desert Storm in 1991, the CH-47D was the main mode of transportation to shift personnel, equipment and supplies. This requirement was repeated in Afghanistan in 2002 and Iraq in 2003.

"The Chinook was essential to the movement of men and materials in the Falklands conflict."

The US Army secured its forward operating base in 1991 by an air assault of the 101st Airborne Division. This air assault, involving 5,000 soldiers, was principally accomplished by 60 Chinooks. In Bosnia, Chinooks carried over 3,000 passengers and lifted more than 3.2 million pounds of cargo over a six-month period.

The German Army Aviation Regiment is now modifying 40 of its 80 Chinooks currently in service.

This will focus on avionic improvements, such as a glass cockpit, as well as introducing four large screens and colour LCDs to replace the flight instruments. An advanced communications suite with datalinks will enable the aircraft to integrate with other advanced systems.

After 50 years of flight service, the Chinook still retains its supreme position in its field.