The HZ-1 Aerocycle , also known as the YHO-2 and by the manufacturer's designation DH-5 Aerocycle , was an American one-man "personal helicopter " developed by de Lackner Helicopters in the mid-1950s. Intended to be operated by inexperienced pilots with a minimum of 20 minutes of instruction, the HZ-1 was expected to become a standard reconnaissance machine with the United States Army . Although early testing showed that the craft had promise for providing mobility on the atomic battlefield , more extensive evaluation proved that the aircraft was in fact too difficult to control for operation by untrained infantrymen , and after a pair of crashes the project was abandoned. A single model of the craft was put on display.
27-494: During the early 1950s, Charles H. Zimmerman of the National Advisory Committee for Aeronautics (NACA) developed a system for control of a rotorcraft in which, with the rotors mounted on the underside of the aircraft, the machine could be steered by the pilot through the simple shifting of his weight and kept stable through the actions of his natural reflexes. Known as kinesthetic control and similar in principle to
54-855: A CH-21 Shawnee near the Laotian-Vietnamese border with the death of four aviators in July 1962 were some of the U.S. Army's earliest casualties in the Vietnam War . Despite these events, the Shawnee continued in service as the U.S. Army's helicopter workhorse in Vietnam until 1964 when it was replaced with the Bell UH-1 Huey . In 1965, the Boeing CH-47 Chinook was deployed to Vietnam and later that year, most CH-21 helicopters were withdrawn from active inventory in
81-558: A chain reduction unit. The aircraft's landing gear consisted of airbags at the end of each arm of the frame along with a large rubber float in the middle, providing amphibious capability, although this arrangement was later replaced by a pair of conventional helicopter-type skids. Originally designated YHO-2 by the U.S. Army, then later re-designated HZ-1 and named "Aerocycle", the prototype made its first tethered flight on 22 November 1954, with its first free flight taking place in January 1955 at
108-528: A personnel parachute. Of the dozen examples of the type ordered by the U.S. Army, only a single example of the HZ-1 has survived, and this aircraft is currently on display in the U.S. Army Transportation Museum at Fort Eustis, Newport News , Virginia. Data from General characteristics Performance Aircraft of comparable role, configuration, and era Related lists Charles H. Zimmerman Too Many Requests If you report this error to
135-484: The Brooklyn Army Terminal . Over 160 flights totaling more than 15 hours of flight time were conducted, and the results of this early test flight program were considered promising enough that a dozen examples of the type were ordered (serial numbers 56-6928 to 56-6939). Predictions were made that the craft could provide transport to a modern version of the old horse cavalry , providing airborne "eyes and ears" for
162-548: The United States Marine Corps (USMC) to evaluate the helicopter as an airborne tug to tow disabled landing ships and amphibious landing vehicles to the beach. During the evaluation, the H-21B towed an LST at 5 kn (9.3 km/h; 5.8 mph) and a simulated tracked amphibious vehicle from the water to the beach. The uprated 1425 hp Wright engine used in the H-21B was also used in subsequent variants sold to both
189-559: The United States Navy a series of tandem rotor helicopters, starting with the HRP-1 of 1944. The HRP-1 was nicknamed the "flying banana" because of the upward angle of the aft fuselage, which ensured that the large rotors could not strike the fuselage in any flight attitude. The name was later applied to other Piasecki helicopters of similar design, including the H-21. In 1949, Piasecki proposed
216-573: The Army. In 1956, the test program was transferred to Fort Eustis , Virginia , where Captain Selmer Sundby took over test-flying duties. The HZ-1 had been designed to be very easy to fly, and early testing indicated that untrained soldiers could learn to operate the craft in less than 20 minutes, and some claiming that only 5 minutes of instruction were required. In addition, the HZ-1 proved to be faster than other flying platform designs evaluated by
243-467: The Army. Sundby, however, quickly determined that the craft was much more difficult to fly than had been expected and would not be safe in the hands of an inexperienced pilot. In addition, the low-mounted rotors proved to be prone to kicking up small rocks and other debris. Over a series of tethered and free-flying test flights lasting up to 43 minutes, the HZ-1 suffered a pair of accidents. Both crashes occurred under similar conditions –
270-657: The CH-21's unprotected control cables and fuel lines proved vulnerable to the Vietcong , which were increasingly well supplied with automatic small arms and heavy (12.7 mm) anti-aircraft machine guns. The H-21, which was designed for cold weather operations, performed poorly in the hot weather of Vietnam. Despite being capable of carrying 20 passengers, it could lift only nine when operating in Vietnam. Pilots reported that engines that were rated for 600 hours of flying time were lasting only 200 hours or less in Vietnam. The shooting down of
297-665: The H-21 had been removed from ground-attack, official U.S. Army evaluations at the time indicated that the type was actually more likely to survive hits by ground fire than was the Sikorsky CH-34; this was assumed to be a consequence of the location and construction of the CH-34's fuel tanks. By the close of the Algerian War, troop-carrying H-21C helicopters were being used in concert with H-34 ground-attack helicopters in large counterinsurgency operations. The H-21C saw extensive service with
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#1732869154880324-684: The H-21A and H-21B were put into service by the USAF and the Royal Canadian Air Force (RCAF) to maintain and service Distant Early Warning Line (DEW) radar installations stretching from the Aleutian Islands and Alaska across the Canadian Arctic to Greenland and Iceland . In 1952, some H-21As were evaluated by USMC helicopter squadron HMX-1 for air assault. In 1957, an H-21B was loaned to
351-461: The H-21C lacked the maneuverability and performance needed for ground-attack. The H-21C was far more successful as a troop transport, and most H-21Cs in service were eventually fitted with flexible door-mounted guns such as the .50 cal. (12.7 mm) M2 Browning machine gun or the (ex- German ) MG 151/20 20 mm aircraft autocannon, for defensive use when landing assault forces under fire. Though
378-499: The U.S. Army (as the H-21C Shawnee ) and the military forces of several other nations. In 1962, the H-21 was renamed the CH-21 in U.S. Army service. In 1959 Vertol Aircraft, the new name for Piasecki Helicopters, came up with a concept for heavy lift over short distances where between two and six H-21Bs would be linked by beams to lift heavy loads. It was considered to be unsafe, because if one helicopter had mechanical problems during
405-516: The U.S. Army, primarily for use in transporting troops and supplies. On 24 August 1954, with the assistance of inflight refueling provided by a U.S. Army U-1A Otter , a H-21C known as Amblin' Annie became the first helicopter to cross the United States non-stop. Experiments were made by the Army in arming the H-21C as a gunship; some Shawnees were armed with flex guns under the nose, while others were fitted with door guns. One experimental version
432-566: The Wikimedia System Administrators, please include the details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 827201845 Upstream caches: cp1108 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 08:32:35 GMT Piasecki H-21 The Piasecki H-21 Workhorse/Shawnee is an American helicopter, the fourth of a line of tandem rotor helicopters designed and built by Piasecki Helicopter (later Boeing Vertol ). Commonly called "the flying banana", it
459-665: The YH-21 Workhorse , which was an improved, all-metal derivative of the HRP-1, to the United States Air Force (USAF). Using two tandem, fully articulated three-bladed counter-rotating rotors, the H-21 was powered by one nine-cylinder Curtis-Wright R-1820-103 Cyclone supercharged 1,150 hp (858 kW) air-cooled radial engine . After the first flight of the YH-21 on 11 April 1952, the USAF ordered 32 H-21A SAR models and 163 of
486-533: The contra-rotating rotors intermeshed and collided, the blades shattering, causing an immediate loss of control resulting in a crash. Aerodynamic testing was conducted in the full-scale wind tunnel at the Langley Research Center , and it was discovered that the Aerocycle's forwards speed was limited by an uncontrollable pitching motion, but rotor-tip clearance was always sufficient. The inability to determine
513-413: The craft. The machine was a simple, cross-shaped frame, with the pilot standing on a platform, secured by a safety harness . The harness also secured the aircraft's engine, which was an outboard motor manufactured by Mercury Marine . The engine was controlled by a twist-grip motorcycle-style throttle and transferred power to the 15-foot (4.6 m) diameter, contra-rotating rotors via belt drive with
540-752: The lift it could unbalance the structure and cause all helicopters to crash. In 1956, seeking a way to use helicopters for ground-attack in the Algerian War , the French Air Force and French Army Aviation ( Aviation Légère de l'Armée de Terre ) experimented with arming the Sikorsky S-55 , then being superseded in service by the more capable Piasecki H-21 and Sikorsky H-34 helicopters. Some French Air Force and Army aviation H-21C helicopters were subsequently armed with fixed, forward-firing rockets and machine guns. A few even had racks for bombs but tests found that
567-400: The mechanics of riding a bicycle or a surfboard , it was hoped that the concept would allow pilots to operate an aircraft with little to no training time. NACA testing proved that the idea had merit, and several companies, including Bensen Aircraft , Hiller Aircraft , and de Lackner Helicopters, began development of rotorcraft using the concept. The concept proposed by de Lackner Helicopters
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#1732869154880594-546: The more powerful H-21B assault transport variant. The H-21B was equipped with an uprated version of the Wright 103 engine, developing 1,425 shaft horsepower (1,063 kW) and featured rotor blades extended by 6 inches (152 mm). With its improved capabilities, the H-21B could carry 22 fully equipped infantrymen or 12 stretchers, plus space for two medical attendants, as a medevac helicopter. With its Arctic winter capabilities,
621-525: The precise cause of the intermeshing, combined with the fact that the "personal lifting device" concept was failing to live up to its expectations, led to the decision to terminate the project. Sundby was awarded the Distinguished Flying Cross for his test-flying work with the HZ-1, going on to test-fly the H-21 and H-34 helicopters, as well as seeing combat in the Vietnam War before retiring with
648-468: The rank of colonel . An entirely new type of parachute with extremely fast opening characteristics, the "Ultra-Fast Opening Personnel Parachute Type XMP-2", was developed for use in testing of the HZ-1 and Hiller VZ-1 flying platforms. Designed for use from 0 to 50 miles per hour (0–80 km/h) and at altitudes as low as 25 feet (7.6 m), the XMP-2 proved to have insufficient reliability for use as
675-399: Was a multi-mission helicopter, capable of being fitted with wheels, skis or floats. The H-21 was originally developed by Piasecki as an Arctic rescue helicopter. The H-21 had cold-weather features permitting operation at temperatures as low as −65 °F (−54 °C) and could be routinely maintained in severe cold weather environments. Piasecki Helicopter designed and successfully sold to
702-410: Was a one-man flying platform and received the company designation "DH-4". The DH-4 was expected to be able to carry up to 120 pounds (54 kg) of cargo or an auxiliary 5-US-gallon (19 L; 4.2 imp gal) fuel tank to extend its range up to 50 miles (80 km) in addition to its pilot. A cargo lifting line could be threaded through the rotor shaft for the carrying of slung loads underneath
729-596: Was tested with a Boeing B-29 Superfortress .50 cal. remote turret mounted beneath the nose. The H-21C (later designated CH-21C) was first deployed to South Vietnam in December 1961 with the Army's 8th and 57th Transportation Companies, in support of Army of the Republic of Vietnam troops. In Army service, the CH-21C Shawnee could be armed with 7.62 mm (.308 in) or 12.7 mm (.50 in) flexible door guns. Relatively slow,
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