(Repost from 2009)
We’ve covered helicopters here before, such as the Huey, the Blackhawk, the OH-58 Kiowa and of course, Cobra and Apache gunships. Let’s talk about the big boy on the block. The Chinook. Or as it became known almost instantly in the Army, the Shithook. The CH-47 is the Army’s largest helicopter, used to transport critical logistical items, troops and artillery around the battlefield.
The Chinook has been around for a long time. It’s first flight was in 1961. But the issues surrounding its development deserve a little attention. In the late 1950s, the Army and helicopter designers began to realize that piston engines would never become a very efficient way of powering helicopters. Gas turbines (jet engines that provided power through a driveshaft, rather than thrust) were finally becoming a practical option for military use. With the advent of these new engines, the Army took a long look at what the next generation of helicopters should look like. Just how big should they be? At the same time, the concept of “air assault” or landing troops directly on the battlefied started to form. What was the best way to move troop unit? Should you use a smaller helicopter that could lift a squad? Or would the better bet be to use somewhat larger helicopters that could lift 15-20 men? Smaller helicopters would cost more in the long run, but losing one helicopter in the assault wouldn’t result in as many casualties. The Army first decided to go with the larger helicopter, of about 20 men. The Vertol Company (later bought by Boeing) provided the Model 107. But the debate in the Army over helicopter size raged on. Some thought that the new UH-1B Huey could be scaled up to carry a full squad. That would handle most air assualt requirements, and still have a relatively cheap helicopter. The Model 107 would be larger than was needed. The other half of the problem was moving artillery and supplies. The Model 107 was just a bit too small for that job. The ideal was to move a 105mm howitzer, its crew, and a load of ammunition all in one lift by one helicopter. Boeing went back to the drawing board. The Model 114 was the result, and was soon bought by the Army as the CH-47 Chinook. And it wasn’t very long before the Chinook found itself in Vietnam, as part of the airmobile 1st Cavalry Division. With Hueys to conduct the initial assualt, and Chinooks bringing in the follow-on elements and moving artillery, the Army’s pattern of air assault missions was set so soundly that it is relatively unchanged 40-odd years later.
But don’t feel bad for the Model 107. Even though it wasn’t selected by the Army, its development continued. Largely because the Marines didn’t have a lot of space on the Navy’s helicopter carriers, they were forced to go with a somewhat larger helicopter. And the Model 107 fit the bill perfectly. They bought it as the CH-46 and operate it to this day.
Early Chinooks had engines of about 2,200 horsepower each. This was very quickly upgraded to about 2,600hp each. And improvements didn’t stop there. The rotor blades, rear pylon design, and transmission were all upgraded through the A, B, and C models to improve performance. In the 1980s, the design was again refreshed, with attention focusing again on more horsepower, but also greatly improved avionics and better reliability, resulting in the CH-47D. Many “D” models were conversions from older models, but there were also quite a few new built airframes. These were delivered up until 2002. And right about the time the last “D” model was delivered, the work on the latest model moved into high gear.
The newest model, the CH-47F is really an old model. While there will be some newbuild airframes, most will be remanufactured CH-47Ds. And since most of the “D” models were remanufactured earlier models, there will be some airframes well over 30 years old that will be expected to soldier on for another 20. Because of this, a large part of the program will be rebuilding them to make them easier to maintain, reducing vibration, making sure the components don’t have any fatigue issues, and making any issues easier to detect. Improvements in the avionics will include updating the instruments to the latest common “glass cockpit” standard, as well as building in the cabapility of operating in the Force XXI digital environment, which is the Army’s version of a battlefield internet. Not surprisingly, the Army is going with more powerful engines as well. The latest version of the Chinook engines put out almost 4,900 hp each. The Chinook has gone from a useful load of 7,000 pounds in its early days, to over 21,000 pounds in the “F” modeland the new models are faster. Think about that. How many of us are faster and stronger now that we’re over 40?
By now, you ought to have figured out that the ‘hook is a pretty capable helicopter. Lots of other folks have reached that conclusion as well. Very few other nations have the same air assault capability that we do, but having a few heavy lift helicopters around is handy for them as well. Several other nations, notable Great Britain, the Dutch, and the Japanese have bought various versions of the Chinook. When Great Britain attacked to recapture the Falklands in 1982, they lost several Chinooks aboard the Atlantic Conveyor. Their one remaining Chinook was put to work, doing the job of several helicopters. In one instance, instead of carrying its normal load of 55 troops, the sole Chinook lifted 105 fully loaded troops. There are several tales of Chinooks in the Vietnam war carrying over 100 people (though usually lightly loaded Vietnamese civilians). I’ve been in a Chinook with about 40 other people- I can’t imagine just how crowded it was with over 100.
It wouldn’t be much of a stretch to say that without the Chinook, the Army in Afghanistan would be crippled. Many of the smaller outposts can only be reached by helicopter. Given the high elevations and hot weather there, Blackhawks, normally very capable birds, struggle to carry a useful load. The Chinook, with its greater power, is able to support these high/hot outposts.
With the new “F’ models just beginning to come into service, we can expect this long serving veteran to serve for as much as 30 more years.
Mind you, we’ve scrimped on discussing the gunship version, or the several special operations versions. But here’s a last look at the bird for you.