When building the world’s finest aircraft for the world’s finest fighting force, experimentation is key to getting it right, and one aircraft provided the trial and error necessary to keep Army Aviation’s heavy lifter flying high.
In 1969, the Army and then-Boeing Vertol entered into a partnership to improve upon their cargo helicopter fleet, and thus the BV-347 was borne from a CH-47A Chinook that was provided by the Army as a technology demonstrator, according to retired CW5 Jim Kale, who now serves as a tour guide for the U.S. Army Aviation Museum.
The aircraft, which sits on the west lawn of the museum, was created for the sole purpose of trying out new technologies, said Kale.
“Within the program, they took an existing aircraft that they knew had real history and they tried a bunch of new technologies on it to see how it would work,” he said.
The most noticeable experimental feature of the aircraft is its wings that extend from the center of the helicopter. The wings were added as a means to improve lift, and although the addition served its purpose, the added weight canceled out any positive effects it provided, said Kale.
The BV-347 was tested for more than two years and flew about 350 hours with the intention to meet five primary goals: improve flying qualities with external loads and instrument flight; improve stability, control and maneuverability in hover flight and forward flight with high gross weight; reduce rotor noise; reduce vibration stress; and create a modern cockpit environment with improved instrument and navigation displays.
While attempting to reach these goals, improvements made to the test helicopter included extending the fuselage about 110 inches, raising the aft pylon 30 inches, installing a four-blade rotor system, installing retracting landing gear, installing an enclosed flight engineering station, testing advanced fly-by-wire control systems and installing an advanced moving map navigation system.
Many of the additions did improve upon the aircraft, said Kale, but the gains were negated by other drawbacks, such as cost or inconvenience.
For example, in an attempt to reduce the noise of the aircraft, a four-bladed rotor system was installed, which helped to reduce noise and vibration by splitting the load between more rotor blades, he said. The issue with installing the new rotor system was that it required the aircraft’s fuselage to be extended and the aft pylon to be raised, essentially rebuilding the entire aircraft.
“The problem with that was that it was too expensive to make the change to the entire fleet of aircraft, so it wasn’t feasible,” said Kale. “It’s advantageous, but just too expensive. The next time (the Army) builds another big helicopter, they can go back and revisit that.”
That’s what the benefit of a program like this is, he added. The Army may not be able to use it in the near future, but in the far future it may be something developers can utilize.
Another improvement that was installed on the aircraft was the moving maps that used paper maps on rollers to pinpoint the location of the aircraft. The issue with the new navigation system was that it took too much additional training and setup to implement across the entire fleet, and the idea was eventually scrapped. The introduction of GPS later negated the need for the paper map system, added Kale.
Not all of the technology that was put into the BV-347 was scrapped, though. The quality of flight was much improved with the addition of fly-by-wire systems, which improved on the control stability of the aircraft and was later incorporated into the CH-47D and later models.
“It’s because of programs like the BV-347 that leads the industry to innovate aircraft into the fleet that Army Aviation uses today,” said Kale.