The HZ-1 Aerocycle, also known as the YHO-2 and by the manufacturer's designation DH-4 Heli-Vector, was an American one-man "personal helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

" developed by de Lackner Helicopters in the mid 1950s. Intended to be operated by inexperienced pilots with a minimum of instruction, the HZ-1 was expected to become a standard reconnaissance

Reconnaissance

Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....

 machine with the United States Army

United States Army

The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. Although early testing showed that the craft had promise for providing mobility on the atomic battlefield

Nuclear warfare

Nuclear warfare, or atomic warfare, is a military conflict or political strategy in which nuclear weaponry is detonated on an opponent. Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage...

, 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.

Design and development

During the early 1950s, Charles H. Zimmerman

Charles H. Zimmerman

Charles Horton Zimmerman , was an aeronautical engineer, whose work on novel airfoil configurations led to several notable experimental aircraft programs.-Early work:...

 of the National Advisory Committee for Aeronautics

National Advisory Committee for Aeronautics

The National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...

 (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 the mechanics of riding a bicycle or a surfboard

Surfboard

A surfboard is an elongated platform used in the sport of surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding a breaking wave...

, it was hoped that the concept would allow for 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

Bensen Aircraft

The Bensen Aircraft Corporation was established by Dr. Igor Bensen at Raleigh-Durham International Airport in North Carolina in 1952 to develop and market a variety of helicopters and autogyros of Bensen's own design....

, Hiller Aircraft

Hiller Aircraft

Hiller Aircraft Company was founded in 1942 as Hiller Industries by Stanley Hiller to develop helicopters.- History :Stanley Hiller, then seventeen, established the first helicopter factory on the West Coast of the United States, located in Berkeley, California, in 1942, under the name "Hiller...

, and de Lackner Helicopters, began development of rotorcraft using the concept.

The concept proposed by de Lackner Helicopters was a one-man flying platform, and it received the company designation "DH-4". The DH-4 was expected to be able to carry up to 120 pounds (54.4 kg) of cargo or an auxiliary 5 gallons (18.9 l) fuel tank to extend its range up to 50 miles (80.5 km) in addition to its pilot; in addition, a cargo lifting line could be threaded through the rotor shaft for the carrying of slung loads underneath the craft.

The machine was a simple, cross-shaped frame, with the pilot standing on a platform, secured by a safety harness

Safety harness

A safety harness is a form of protective equipment designed to protect a person, animal, or object from injury or damage. The harness is an attachment between a stationary and non-stationary object and is usually fabricated from rope, cable or webbing and locking hardware...

. The harness also secured the aircraft's engine, which was an outboard motor

Outboard motor

An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom and are the most common motorized method of propelling small watercraft...

 manufactured by Mercury Marine

Mercury Marine

Mercury Marine, founded in 1939, is a division of Brunswick of Lake Forest, Illinois, in the United States. Mercury provides engines for private, commercial and government sales. Mercury also has its own line of very successful racing engines tailored for power and speed. The company's primary...

. The engine was controlled by a twist-grip, motorcycle-style throttle and transferred power to the 15 feet (4.6 m) diameter, contra-rotating rotors via belt drive with 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, allowing for amphibious capability, although this arrangement was later replaced by a pair of conventional helicopter-type skids.

Testing

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 the Brooklyn Army Terminal

Brooklyn Army Terminal

The Brooklyn Army Terminal is large complex of piers, docks, warehouses, cranes, rail sidings and cargo loading equipment on between 58th and 63rd Street in Sunset Park, Brooklyn. During World War II, the terminal was responsible for shipment of 85% of army equipment and personnel overseas;...

. 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

Cavalry

Cavalry or horsemen were soldiers or warriors who fought mounted on horseback. Cavalry were historically the third oldest and the most mobile of the combat arms...

, providing airborne "eyes and ears" for the Army.

In 1956, the test program was transferred to Fort Eustis

Joint Base Langley–Eustis

Joint Base Langley–Eustis is a United States military facility located in Hampton and Newport News, Virginia. The facility is under the jurisdiction of the United States Air Force 633rd Air Base Wing, Air Combat Command...

, Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

, 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 five minutes of instruction were required. In addition, the HZ-1 proved to be faster than other flying platfom designs evaluated by 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 – 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

Wind tunnel

A wind tunnel is a research tool used in aerodynamic research to study the effects of air moving past solid objects.-Theory of operation:Wind tunnels were first proposed as a means of studying vehicles in free flight...

 at the Langley Research Center

Langley Research Center

Langley Research Center is the oldest of NASA's field centers, located in Hampton, Virginia, United States. It directly borders Poquoson, Virginia and Langley Air Force Base...

, 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 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

Distinguished Flying Cross (United States)

The Distinguished Flying Cross is a medal awarded to any officer or enlisted member of the United States armed forces who distinguishes himself or herself in support of operations by "heroism or extraordinary achievement while participating in an aerial flight, subsequent to November 11, 1918." The...

 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

Vietnam War

The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

 before retiring with the rank of colonel

Colonel (United States)

In the United States Army, Air Force, and Marine Corps, colonel is a senior field grade military officer rank just above the rank of lieutenant colonel and just below the rank of brigadier general...

.

Parachute development

An entirely new type of parachute

Parachute

A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

 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- and at altitudes as low as 25 feet (7.6 m), the XMP-2 proved to have insufficient reliability for use as a personnel parachute.

Aircraft on display

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

U.S. Army Transportation Museum

The U.S. Army Transportation Museum is a United States Army museum of vehicles and other transportation-related equipment and memorabilia. It is located on the grounds of Fort Eustis, Virginia, in Newport News, on the Virginia Peninsula.-History:...

 at Fort Eustis, Newport News

Newport News, Virginia

Newport News is an independent city located in the Hampton Roads metropolitan area of Virginia. It is at the southeastern end of the Virginia Peninsula, on the north shore of the James River extending southeast from Skiffe's Creek along many miles of waterfront to the river's mouth at Newport News...

, Virginia.

Specifications

See also

External links

• "The Sky-High Invention" on howtoadvice.com
• Science: Vertical Mobility. TIME, 9 January 1956.