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
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
" 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
In military operations, reconnaissance or scouting is the exploration of an area by military forces to obtain information about enemy forces, terrain, and other activities.
Examples of reconnaissance include patrolling by troops (skirmisher ...
machine with the
United States Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
. 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
Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and marine i ...
, 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 of the
National Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics (NACA) was a United States 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 ...
(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
A surfboard is a narrow plank used in surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding an ocean wave. They were invented in ancient Hawaii, where they were known as ''papa he'e ...
,
[Hiller Aviation Museum] 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
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.
History
The most successfu ...
,
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 Berkel ...
, 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 of cargo
[Goebel 2011] or an auxiliary fuel tank to extend its range up to
[''Mechanix Illustrated'' 1955] in addition to its pilot, 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
A safety harness is a form of protective equipment
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards a ...
. The harness also secured the aircraft's engine, which was an
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. They are the most common motorised method ...
manufactured by
Mercury Marine
Mercury Marine is a marine engine division of Brunswick Corporation headquartered in Fond du Lac, Wisconsin. The main product line is outboard motors. It also produces the MerCruiser line of sterndrives and inboard motors. Some manufacturing ...
.
The engine was controlled by a
twist-grip
A twistgrip is a handle that can be twisted to operate a control. It is commonly found as a motorcycle's right handlebar grip to control the throttle, but is sometimes found elsewhere, such as on a bicycle as a gearshift, and in helicopters.
Hi ...
motorcycle-style throttle
and transferred power to the diameter, contra-rotating rotors via belt drive
with a chain reduction unit.
[Champlin 1953] 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.
[Harding 1997, p. 112.]
Testing
![De Lackner HZ-1 test flown by Captain Sundby](https://upload.wikimedia.org/wikipedia/commons/8/8c/De_Lackner_HZ-1_test_flown_by_Captain_Sundby.png)
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,
[''The Aeroplane'', v. 88, 1955. p. 443.] with its first free flight taking place in January 1955 at the
Brooklyn Army Terminal
The Brooklyn Army Terminal (BAT) is a large warehouse complex in Sunset Park, Brooklyn, New York City. The site occupies more than between 58th and 63rd Streets west of Second Avenue, on Brooklyn's western shore. The complex was originally u ...
.
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
Historically, cavalry (from the French word ''cavalerie'', itself derived from "cheval" meaning "horse") are soldiers or warriors who fight mounted on horseback. Cavalry were the most mobile of the combat arms, operating as light cavalry ...
, providing airborne "eyes and ears" for the Army.
In 1956, the test program was transferred to
Fort Eustis
Fort Eustis is a United States Army installation in Newport News, Virginia. In 2010, it was combined with nearby Langley Air Force Base to form Joint Base Langley–Eustis.
The post is the home to the United States Army Training and Doctrine Co ...
,
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
, 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,
[''Flight and Aircraft Engineer'', 2 November 1956, p. 724.] and some claiming that only five minutes of instruction were required. In addition, the HZ-1 proved to be faster than other flying platform designs evaluated by the Army.
Sundby, however, quickly determined that the craft was much more difficult to fly than had been expected,
[U.S. Army Transportation Museum] 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 tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...
at the
Langley Research Center
The Langley Research Center (LaRC or NASA Langley), located in Hampton, Virginia, United States of America, is the oldest of NASA's field centers. It directly borders Langley Air Force Base and the Back River on the Chesapeake Bay. LaRC has fo ...
, 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 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
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
before retiring with the rank of
colonel
Colonel (abbreviated as Col., Col or COL) is a senior military officer rank used in many countries. It is also used in some police forces and paramilitary organizations.
In the 17th, 18th and 19th centuries, a colonel was typically in charge of ...
.
Parachute development
![HZ-1 Aerocycle following crash](https://upload.wikimedia.org/wikipedia/commons/0/08/HZ-1_Aerocycle_following_crash.png)
An entirely new type of
parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who ...
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 and at altitudes as low as , the XMP-2 proved to have insufficient reliability for use as a personnel parachute.
"Ultra-fast Opening Personnel Parachute Type XMP-2"
Defense Technical Information Center. Accessed 27 May 2010.
Variants
;DH-4 Heli-Vector: Initial prototype of the Aerocycle design; one built.
;DH-5 Aerocycle: Company designation for the development prototype of the HZ-1.
;HZ-1 Aerocycle: the limited production aircraft delivered to the US Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
; 12 built.
;HO-2 Aerocycle: Designation in the US Army HO series
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 at Fort Eustis, Newport News
Newport News () is an independent city in the U.S. state of Virginia. At the 2020 census, the population was 186,247. Located in the Hampton Roads region, it is the 5th most populous city in Virginia and 140th most populous city in the Uni ...
, Virginia.
Specifications (HZ-1 Aerocycle)
See also
References
;Notes
;Bibliography
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External links
The Sky-High Invention
at howtoadvice.com
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{{DISPLAYTITLE:de Lackner HZ-1 Aerocycle
HZ-1
United States military helicopters
1950s United States experimental aircraft
Coaxial rotor helicopters
1950s United States helicopters
Cancelled military aircraft projects of the United States
Single-engined piston helicopters
Aircraft first flown in 1954