The Piasecki CH21-C, referred to as the Flying Banana, was used extensively by the U.S. Navy, Air Force, Army, and many foreign militaries.
The Piasecki "Flying Banana" entered service in the 1950s.
Frank Piasecki
Before developing the tandem helicopters for which he is known, Frank Piasecki built and flew the PV-2 single-rotor craft in 1943. A result of three years' research by his company, the P-V Engineering Forum, it had a three-bladed, 25-foot (7.6-meter) rotor and was 22 feet (6.7 meters) long.
Piasecki's "Flying Banana" served as a forerunner to this Boeing-Vertol CH-47.
This CH-46 Sea Knight performs sea-based support functions.
The CH-47 Chinook helicopter is the U.S. Army's only medium-lift helicopter. It is a twin-engine, tandem rotor, cargo helicopter. Beginning in 1975, it was modernized to include new fiberglass rotor blades, transmission and drive systems, modularized hydraulics, electrical systems, advanced flight controls, triple hook cargo system, and an auxiliary power unit.
The CH-46E Sea Knight helicopter is used by the U.S. Marine Corps as a medium-lift assault helicopter primarily to move troops. It provides all-weather, day-or-night assault transport of combat troops, supplies, and equipment. The CH-46 Sea Knight was first procured in 1964 to meet the medium-lift requirements of the Marine Corps in Vietnam.
The U.S. Coast Guard and Navy have used the Piasecki "Dogship" (PV-3/HRP-1) as a rescue craft. It has ten seats and is powered by a 600 hp Pratt & Whitney R-1340 engine.
The Soviet firm Yakovlev manufactured a tandem-rotor craft starting in the 1950s, designated the Yak-24.
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Piasecki—The Dogship and the Flying BananaAlthough Frank Piasecki was born in Philadelphia in 1919, the son of an immigrant Polish tailor. He earned degrees in aeronautical and mechanical engineering by the age of 20 and in 1940, he gained the support of a few friends and started a small aeronautical company. He built a single-person, single-rotor helicopter designated the PV-2 and test-flew it by 1943. Piasecki realized that Piasecki decided to build a helicopter that had The Dogship weighed 5,000 pounds (2,268 kilograms) empty and less than 7,000 pounds (3,175 kilograms) fully loaded. Its fuselage had an enormous 400 cubic feet (11.3 cubic meters) of space. The fuselage was constructed of tubular steel filled with wooden ribs and covered with fabric. A 450-horsepower (336-kilowatt) Continental R-975 radial engine was housed amidship with shafts angling forward and aft to the rotors. Automotive gears were used in its transmission. During the first test flight, the Dogship flew without its fabric covering, looking like a skeletal praying mantis. Soon after, during another early test, the craft rose off the ground and pitched up suddenly, its rear rotor coming alarmingly close to the ground. During a later test flight, the helicopter's transmission grew dangerously hot. Piasecki did not want to perform repairs at the Navy field and let Navy personnel see that he was having problems with his aircraft, so he sent his flight engineer to buy ice and soda pop, which they then poured over the transmission to cool it. After a harrowing low-level flight back to the factory outside Philadelphia, the Dogship landed and its rotors came to an unusually abrupt halt. The engineers opened the transmission and realized in horror that all the gears had been stripped nearly clean. They had to redesign the transmission using parts much more tough than the automotive parts they had started with—learning a lesson that aircraft required more robust designs and parts than automobiles. Despite these early problems, the tandem-rotor configuration soon proved itself highly capable. After the war, Piasecki received a contract to build a military prototype called the XHRP-1, which was similar to the Dogship. The Navy then ordered several more to use as rescue craft, since they could retrieve more than one person at a time. The craft could carry ten men in addition to the pilot and copilot. Navy leaders still had little interest in helicopters at this stage and passed most of the HRP-1s onto the Marines and Coast Guard. To ensure that the rotors did not hit each other, the rear end of the fuselage curved upwards so the rear rotor was higher than the forward rotor. Because of this odd shape, the craft soon acquired the nickname Flying Banana. This nickname would also be applied to later Piasecki craft, such as the HRP-2 and the highly successful H-21, which entered service in the 1950s and which was used by the U.S. Navy, Air Force, Army and many foreign militaries. All had the same tandem-rotor configuration pioneered by the Dogship. Piasecki eventually became Vertol and was later acquired by Boeing. The Dogship and later the Flying Banana would serve as the forerunners to a number of tandem-rotor craft ultimately produced in the hundreds, such as the Navy/Marines CH-46 Sea Knight and the Army's heavy-duty workhorse CH-47 Chinook. Both types saw extensive use in Vietnam and later. The CH-46 was still in naval use in 2000 for "Vertical Replenishment" or "VERTREP" at sea, where a helicopter is used to lift cargo from one ship to another. The Marines also still use the Sea Knight, but hope to replace it with the V-22 Osprey. The CH-47 was also in use carrying jeeps, artillery, and other supplies slung under its fuselage on cables. Special Operations versions, equipped with refueling probes and night vision equipment, are used to place troops deep behind enemy lines. The Chinook has been exported to a number of countries where it has been highly successful and serves in a number of foreign militaries including Argentina, Egypt, Greece, Iran, Italy, Japan, Morocco, Netherlands, Singapore, South Korea, Spain, Taiwan, and the United Kingdom. Both the CH-46 and CH-47 were produced in civilian versions, although not in large numbers. In the civilian role, they are often used as heavy-lift "skycranes." One other helicopter manufacturer, the British firm Bristol, copied the basic tandem-rotor layout. Bristol produced the Belvedere in the early 1960s. The Belvedere, which looked like a baguette with rotors on either end, saw service in Borneo. The Soviet Union design firm Yakovlev manufactured a tandem-rotor craft starting in the 1950s known as the Yak-24. But by far the most successful helicopter of this type is the Chinook, which has also been produced under license in Italy by Agusta and in Japan. Over a thousand have been built. Dwayne A. Day Sources: Carey, Keith. The Helicopter. Blue Ridge Summit, PA: Tab Books, 1986. Gunston, Bill. Helicopters of the World. New York: Crescent Books, 1983. Simpson, Rod. Airlife's Helicopters & Rotorcraft. Shrewsbury, England: Airlife, 1998. Spenser, Jay P. Whirlybirds: A History of U.S. Helicopter Pioneers. Seattle, WA: University of Washington Press, 1998. Young, Warren R. The Helicopters. Alexandria, VA: Time-Life Books, 1982. Further Reading: Simpson, Rod. Airlife's Helicopters & Rotorcraft. Shrewsbury, England: Airlife, 1998. Spenser, Jay P. Whirlybirds: A History of U.S. Helicopter Pioneers. Seattle, WA: University of Washington Press, 1998. Young, Warren R. The Helicopters. Alexandria, VA: Time-Life Books, 1982. Hirschberg, Michael J. and Daley, David K. "US and Russian Helicopter Development in the 20th Century. American Helicopter Society International, 2000. http://vtol.org/History.htm.
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