BOEING CH-47 CHINOOK
The Boeing CH-47 Chinook was and is, arguably one of the most versatile and longest serving military aircraft in operation today.
Serving with both military services and private companies across the globe it is also one of the heaviest lifting Western helicopters in operational service.
In the late 1950s, the US Army announced their intention to replace their ageing fleet of the piston engine Korean war era Sikorsky CH-37s with a new gas turbine powered helicopter.
The new gas turbines had already proved extremely successful in the US Army’s Bell UH1 Huey Utility Chopper with its combination of ease of maintenance, light weight and superior power to its piston engined counterparts.
A design competition was announced and after a number of capability trials and submissions, Boeing were requested to develop their winning entry further.
Unfortunately this was to be severely hampered by a split amongst senior Army officials with some administrators arguing the new helicopter should be operated as a light tactical transport with the capability to carry up to 15 troops into battle. Others argued that the new helicopter should be much larger and able to airlift large artillery pieces and have enough internal storage capacity to carry the new Pershing Missile System.
The impasse was finally removed when Bell expanded their development of the UHI by updating its power plant and extending its fuselage to fulfil the troop carrying role. Boeing were now free to develop their heavy lift, large capacity chopper.
In 1957 the American rotorcraft company Vertol and their manufacturing arm Boeing Vertol, began work on a new tandem-rotor helicopter the YHC-1A but the Army considered it too heavy for their intended assault role whilst also too light for a more general heavy transport and lift role.
In 1962, a redesigned, twin-engined gas turbine derivative of the YHC was rolled out of the Boeing hangers. The Chinook CH-47A.
Named after the Chinook peoples of the Pacific Northwest, the CH-47A was powered by twin Lycoming T55 turboshaft engines, mounted on each side of the helicopter’s rear pylon and connected to the rotors by drive shafts.
The twin counter rotating blades of the Chinook eliminated the need for an anti-torque vertical tail rotor allowing the CH-47A to use its full power for lift and thrust.
The Chinook’s ability to adjust lift in either rotor made it less sensitive to changes in its centre of gravity which was of critical importance for lifting heavy cargo or dropping supplies.
In hovering mode, a twin-rotor helicopter has far greater stability than a single rotor when weight is added o removed such as a troop or cargo drop or an emergency cliff top evacuation where limited ground access may often only allow the helicopter to rest its rear door on the ground whilst the remainder of the aircraft hovers in midair.
The other advantage, particularly in a military operation was the fact that should one of the two Lycoming engines fail, the remaining engine was still capable of driving both forward and rear rotors.
With the introduction of the Chinook into the field the US Army actually got the best of both worlds by being able to use both their Bell Huey light weight rapid deployment assault choppers in tandem with the heavy lift and carrying capacity of the Chinook which accelerated their air mobility in conflict actions such as Vietnam and later, Iraq and Afghanistan.
In February 1966, the US Army took delivery of 161 Chinook heavy-lift choppers with the 1st Cavalry Division and the 147th Company despatching them to active service in the escalating conflict in Vietnam. As fighting grew fierce, Chinook crews found themselves having to mount a M60 Machine gun at each of the forward doors and occasionally, a M2 machine gun to fire from the rear cargo door.
Apart from its significant lifting and carrying capacity, the Chinook’s biggest asset was its cargo access via two forward large cargo doors and the drop down rear door.
One of the most spectacular mission in Vietnam for the Chinook was the placing of artillery batteries in perilous mountain positions inaccessible by any other means, and then keeping them resupplied. The 1st Cavalry Division found that its CH-47s were limited to a 3,200 kg payload when operating at altitude, but could carry an additional 450 kg when operating near the coast.
In 1976, Libya purchased 24 Italian-built Chinooks for use against neighbouring Chad ground forces. Without the local support required to operate or maintain the Ch-47s, Libya also recruited western pilots and technicians to keep their fleet in the air.
That purchase opened the flood gates from orders from nations across the globe and the Chinook soon become the staple heavy lift transport for the military everywhere.
Chinooks were operated by both British and Argentine forces during the Falklands War of 1982 and 163 CH-47s were later dispatched to Saudi Arabia, Kuwait and Iraq operation Desert Storm in the early 1990s.
With large coalition forces working alongside the US in Afghanistan, Chinooks were flown by Britain, Italy, the Netherlands, Spain, Canada and Australia.
Today, successive and updated variations of the Chinook are still operated by military forces as well as private industry being used in forestry, disaster relief and aero medical evacuation and firefighting and with over 60 years of operational service, this highly successful helicopter is likely to be with us for many more to come.
All Boeing CH-47 Chinook Instruments come complete with detailed Scale Model, Mango Wood Stand & Plaque plus Printed Fact Sheet featuring photo of instrument in aircraft cockpit.
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VIETNAM ERA, BOEING CH-47 CHINOOK LONGDITUDINAL CYCLIC TRIM INDICATOR
Rare Boeing CH-47 Chinook heavy-lift, helicopter Longitudinal Cyclic Trim Indicator