AVIATION

After 50 Years, There Is No End in Sight for the Chinook

4/1/2012
By Stew Magnuson
RIDLEY TOWNSHIP, Pa. — The Army recently sent a circa 1968 CH-47 Chinook to this sprawling helicopter factory along the banks of the Delaware River to have it refurbished so it can again be dispatched on missions.

April will mark the 50th anniversary of when the service received the first delivery of the twin-rotor, heavy-lift chopper. And of all the aircraft its manufacturer The Boeing Co. has produced since 1910, the Chinook is by far the company’s longest lasting, and most enduring product.  

So, how much longer can U.S. troops expect to look at the sky and see the familiar silhouette of a Chinook flying by?

Consider that the new F-model, which was introduced in 2007, will not replace all its D-model predecessors until 2019 or 2020, said J. Patrick Donnelly, Chinook program manager at Boeing. The best estimate for when an Army program that would introduce a new heavy lift helicopter will come to fruition is about 2030. But it takes about 14 years to swap one model’s inventory out for another.

“That leaves them around to 2040 to 2050 without batting an eye. So that puts us at 90 years, and it’s anyone’s speculation as to what happens” after that, Donnelly said.

Boeing clearly believes in the Chinook’s long-term future. It was putting the finishing touches on a $130 million project to modernize its factory here in the Philadelphia outskirts. All that remained were some new classrooms and remodeled cafeterias for the workers.

The Army has a nascent program called Future Vertical Lift, formerly known as the Joint Multirole Helicopter. When, and if, that gets going in earnest remains to be seen. The Obama administration’s fiscal year 2013 budget proposal calls for Army aviation modernization programs to be pushed back by two years.

Meanwhile, the Chinook remains a popular export. Twenty nations currently have them in their inventories. Foreign sales could keep the line going after the U.S. Army finds a replacement some two decades from now.

“My goal is to keep the Chinook technically relevant until its time is up,” Donnelly said.
One of the improvements is a new rotor blade, which the Army and company officials hope will add 1,500 pounds — and possibly up to a ton — of new lift capability.

The program just finished its critical design review, and Boeing will begin to produce the improved blades for more extensive testing. The last time the Chinook had new blades was 1980 when composite materials replaced metal, Donnelly said.

A platitude often served up when major programs are canceled before they come to fruition is that the millions or billions spent on research and development were not completely wasted. The service assures the taxpayers that the lessons learned and data gathered can be applied to some future programs.

That actually happened in this case. The new approach to the rotor blade had its roots in two failed programs, the Army’s Comanche, which was canceled in 2004, and the Air Force’s Combat Search and Rescue Replacement Aircraft, terminated in 2009.

Boeing was a bidder on both programs. The Air Force, however, was looking for more speed for its CSAR-X helicopter. In this case, the Army wanted more lift. The Chinook is already the fastest helicopter in the Army.

Despite being able to draw upon earlier research-and-development efforts, Boeing engineers had a tough challenge adapting their improved blade ideas to the Chinook.

The bulk of the current composite blade’s inside is resin and honeycombed paper with a graphite and glass composite covering. The edge that cuts through the air is made of titanium in order to stave off erosion caused by rain or sand.

The Army wanted more lift, but any solution concerning the blade could not affect the other performance parameters.

“The customer said, ‘I want to get lift up, but don’t mess up my speed capability. Don’t mess up forward flight. Don’t add more drag,’” Donnelly said.

Further, the new blade could not force alterations to any other part of the aircraft. It had to connect to the hub the same way, and had to be about the same weight and length. Making it longer could cause it to hit the blade in front or behind it. It also couldn’t be more expensive to maintain or result in any other parts of the helicopter increasing their operating costs.

The solution was changing the shape of the blade’s tip. Where it is now relatively straight, the new blade had subtle curves or “twists.” The composite materials it comprises have remained the same.

The tip travels faster than any other part of the blade. At Mach 0.9, it nearly hits the speed of sound. Generally, the more twist to the blade, the more it can lift. The tradeoff is that this degrades forward flight. Boeing had to strike a delicate balance when reshaping the blade in order to meet the Army’s requirement that it not affect the aircraft’s speed.

Advances in composite manufacturing processes have made forming the irregularly shaped tip possible, Donnelly said.

Boeing has completed some wind tunnel testing on the blade to ensure it did not affect forward flight. It has yet to be determined how much extra lift capability will be added.

“Our initial goal is 1,500 pounds. We’re predicting more than that, but I guess we’ll have to wait and see what happens,” Donnelly said. “Almost a ton of lift is what we see coming out of this rotor-blade capability.”

He is uncertain of whether it will reduce the acoustic signature, because that has not been looked at yet. “It could very well, but that’s not a requirement we have on this blade.”

Now that Boeing has the go-ahead to build more blades, further testing may show reduced noise.

Next the company will be sending some blades to a special facility that can simulate lightning strikes. Chinook blades attract bolts, and all blades have to be able to absorb the strike and disperse the energy into the airframe without causing damage.

Until the company can gather more data on manufacturing, it won’t be known whether the new blades will be less expensive, and can save the Army money.

“As we figure out how to build this blade, we certainly will be targeting that it will be no more expensive — and certainly would like to drive it to be cheaper to make — than existing blades. But that’s not proven yet,” Donnelly said.

The long-term plan is to replace all the F-model blades with the advanced composite blades, Donnelly said. The new blade will also be available on export aircraft, he added.

The Army, meanwhile, will continue to look for ways to improve the Chinook. The F-model was a major redesign compared to its predecessors. Its fuselage, for example, has almost 50 percent fewer parts than the D-model. A new cargo roller system that makes life easier for those loading pallets into and off the aircraft was introduced last year, as was a health unit monitoring system that tells maintenance crews and pilots when systems are wearing down. These two new capabilities are being retrofitted on older F-models, but will be standard on new builds.

Next, Boeing will be reevaluating the engines and transmission, Donnelly said. Again, the goal will be to see if improvements will allow the aircraft to lift more.

Also, reducing the weight to other parts of the aircraft would allow the Army and other customers to put in more cargo or personnel.

“Over the life of the aircraft, we have increased its empty weight by 100 pounds a year because I’m putting in new features. I’m changing things. I’m making this better,” Donnelly said.

“But I am taking away soldiers out of the back of that aircraft. I’m taking away water. I’m taking away bullets.”

 The F-models will be in production until about 2020.

“You can get more radical after that. Can I make the Chinook longer?” he asked. Could the blades be extended? If so, that would mean redesigning the hub.  

“That is all under discussion with our customer [the Army], and the requirements guys,” Donnelly said.

The newly refurbished factory has doubled the number of CH-47Fs it produces each month for the Army from about two to four. Boeing increased the number of work stations from eight to 11, and every four days, a helicopter moves up the line.

That number does not include custom aircraft for special operations forces and international orders. A separate manufacturing line that can accommodate the unique specifications of those customers is alongside the F-model line.   

Variants for Canada, Italy and the Netherlands are all in various stages of manufacturing this year.

The factory was originally built in the early 20th century for locomotives. Boeing has been here since 1966. For most of its life, it was a windowless concrete structure with no air conditioning in the summer. Employees had to open massive doors to let in air, which only brought in coal dust from a nearby power plant.

Along with the upgrades that allowed for more efficiency, the factory is now climate controlled, features windows to let in natural light, and has been certified as a Leadership in Energy and Environmental Design facility.

At the end of the line, a Chinook covered in yellow primer paint was waiting to go into a special room that simulates heavy rain. Once that test was complete, it would get its final coat of paint, and would then be ready for a test flight over the Delaware River.

On the day Donnelly spoke, the office of the secretary of defense approved a second multi-year contract for the CH-47F. The decision to give Boeing a five-year contract as opposed to a series of one-year deals must clear Congress, but the news bodes well for the program, Donnelly said.

So, is there any end in sight for the Chinook?

“I hope not,” Donnelly said.               

Topics: Aviation, Rotary Wing

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