HOME

TheInfoList



OR:

The Boeing Vertol YUH-61 (company designation Model 179) was a twin turbine-engined, medium-lift, military assault/utility
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 ...
. The YUH-61 was the runner-up in 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 ...
Utility Tactical Transport Aircraft System (UTTAS) competition in the early 1970s to replace the
Bell UH-1 Iroquois The Bell UH-1 Iroquois (nicknamed "Huey") is a utility military helicopter designed and produced by the American aerospace company Bell Helicopter. It is the first member of the prolific Huey family, as well as the first turbine-powered helic ...
helicopter. At the end of the flyoff program,
Sikorsky Aircraft Sikorsky Aircraft is an American aircraft manufacturer based in Stratford, Connecticut. It was established by aviation pioneer Igor Sikorsky in 1923 and was among the first companies to manufacture helicopters for civilian and military use. Pre ...
was awarded a contract to develop and build its UH-60A entry.


Development

Under a contract awarded in August 1972, Boeing Vertol designed and delivered three prototypes to compete UTTAS program.Gunston, Bill: ''The Illustrated Encyclopedia of the World's Modern Military Aircraft'', page 205. Crescent Books, New York, NY USA, ca. 1978. When Boeing Vertol failed to win the Army competition, it pinned its hope on winning civil orders and the US Navy's LAMPS III program. In the end, a variant of the Sikorsky design, the
SH-60B The Sikorsky SH-60/MH-60 Seahawk (or Sea Hawk) is a twin turboshaft engine, multi-mission United States Navy helicopter based on the United States Army UH-60 Black Hawk and a member of the Sikorsky S-70 family. The most significant modificatio ...
, won the Navy contract, and the civil orders received were canceled. Three aircraft were built and a further two were cancelled and not completed. An attack helicopter design, using the YUH-61's dynamic system (engines, rotor systems and gearboxes), was proposed for the
Advanced Attack Helicopter The Advanced Attack Helicopter (AAH) was a United States Army program to develop an advanced ground attack helicopter beginning in 1972. The Advanced Attack Helicopter program followed cancellation of the Lockheed AH-56 Cheyenne. After evaluat ...
(AAH) competition, but did not make the downselect that resulted in the
Bell YAH-63 The Bell YAH-63 (Model 409) was an experimental attack helicopter for the Advanced Attack Helicopter (AAH) competition. Hughes' ''Model 77/YAH-64'', later developed into the AH-64 Apache, was selected over Bell's entry. Design and development ...
and Hughes YAH-64 being built. The Boeing Vertol AAH design was unique in that the crew were seated in a laterally staggered tandem configuration.


Design

The YUH-61 was designed to meet the UTTAS requirements for improved
reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * High availability * Reliability (computer networking), a ...
,
survivability Survivability is the ability to remain alive or continue to exist. The term has more specific meaning in certain contexts. Ecological Following disruptive forces such as flood, fire, disease, war, or climate change some species of flora, fauna, ...
and lower life-cycle costs, resulting in features such as dual-engines with improved
hot and high In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. The lower air density reduces the power output from the airc ...
altitude performance, and a
modular design Modular design, or modularity in design, is a design principle that subdivides a system into smaller parts called ''modules'' (such as modular process skids), which can be independently created, modified, replaced, or exchanged with other modules ...
(reduced maintenance footprint); run-dry
gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
es; ballistically tolerant, redundant subsystems (hydraulic, electrical and flight controls);
crashworthy Crashworthiness is the ability of a structure to protect its occupants during an impact. This is commonly tested when investigating the safety of aircraft and vehicles. Depending on the nature of the impact and the vehicle involved, different crit ...
crew (
armored Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...
) and troop seats; dual-stage oleo main
landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
; ballistically tolerant, crashworthy main structure; quieter, more robust
main Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany * Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries ...
and
tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...
rotor systems; and a ballistically tolerant, crashworthy fuel system. Transport aboard the
C-130 The Lockheed C-130 Hercules is an American four-engine turboprop military transport aircraft designed and built by Lockheed (now Lockheed Martin). Capable of using unprepared runways for takeoffs and landings, the C-130 was originally desig ...
limited the UTTAS cabin height and length. This also resulted in the main rotor being mounted very close to the cabin roof. While Sikorsky chose a fully articulated rotor head with
elastomeric An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic p ...
bearings, Boeing Vertol chose a rigid main rotor design, based upon technology supplied by MBB, which was partnered with Boeing Vertol at the time.Leoni 2007 Boeing Vertol also selected to use a
tricycle landing gear Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle g ...
and a pusher tail rotor, as opposed to the tail wheel configuration and canted tractor tail rotor that Sikorsky chose, meaning that the thrust produced by the tail rotor was directed away from the vertical stabilizer, while the Sikorsky's flowed around it.


Variants

*Model 237: naval version of the YUH-61 for the
USN The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage o ...
's LAMPS II competition (ship-based multi-purpose helicopter) and lost out to
Sikorsky SH-60 Seahawk The Sikorsky SH-60/MH-60 Seahawk (or Sea Hawk) is a twin turboshaft engine, multi-mission United States Navy helicopter based on the United States Army UH-60 Black Hawk and a member of the Sikorsky S-70 family. The most significant modificatio ...
; no models built *Model 179: civilian 14–20 passenger utility helicopter later canceled; 1 model built


Surviving aircraft

Two of the three aircraft (73-21656 and 73-21658) built are preserved at the
United States Army Aviation Museum The United States Army Aviation Museum is an aviation museum located on Fort Rucker near Daleville, Alabama. It has the largest collection of helicopters held by a museum in the world.Phillips 1992, p. 37.Purner 2004, p. 204. The museum features ...
in
Fort Rucker Fort Rucker is a U.S. Army post located primarily in Dale County, Alabama, United States. It was named for a Civil War officer, Confederate General Edmund Rucker. The post is the primary flight training installation for U.S. Army Aviators and ...
,
Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...
.


Specifications (YUH-61A)


See also


References

;Bibliography *Leoni, Ray D. ''Black Hawk, The Story of a World Class Helicopter''. American Institute of Aeronautics and Astronautics, 2007. .


External links


UTTAS program
€”YUH-61 origins {{USAF helicopters H-061 Boeing YUH-61 Boeing H-61 1970s United States helicopters Aircraft first flown in 1974