Light Observation Helicopter
Encyclopedia
The Light Observation Helicopter (LOH) program was a United States Army
program to evaluate, develop and field a light scout helicopter to replace the Army's aging OH-13 Sioux. The program gained impetus with the advent of the Vietnam War
and was aided by advances in helicopter technology, specifically the development of the turboshaft
engine. Three of the aircraft evaluated for the program would eventually enter military service, one as a training helicopter and two as observation helicopters used for battlefield reconnaissance
missions.
John Dahlquist, Chief, Army Field Forces (AFF), forwarded desirable military characteristics for a two-place reconnaissance helicopter to Army Headquarters. Nearly a year later, in May 1954, Dahlquist's office once again emphasized the need for replacement aircraft and recommended procurement of troop test quantities of the YH-32
. Preliminary evaluation of the YH-32 design revealed that the aircraft was unsuitable for the mission, and the tests were canceled.
In 1955, the Army Field Forces were transformed into the Continental Army Command (CONARC). Dahlquist, who had been promoted to 4-star General on 18 August 1954, continued in command. On 11 October 1955, CONARC recommended that the Department of the Army initiate a program to develop a replacement observation helicopter for the aging OH-13 Sioux and OH-23 Raven. Army's Chief of Research and Development agreed to include the requirement for a new helicopter in the budget for fiscal year 1957 on 19 March 1956, after CONARC highlighted the continued lack of development for replacement aircraft.
During the course of the next three years, three helicopters would be evaluated as candidates to replace the OH-13 and OH-23; the Sud-Ouest Djinn
, the Hughes 269
, and the Brantly B-2
. The aircraft were designated the YHO-1 DJ, YHO-2 HU, and YHO-3 BR, respectively. By October 1958, service testing of Sud Aviation YHO-1 DJ was completed. The following year saw the completion of the desert and temperate temperature testing of the YHO-2 HU. The YHO-3 BR did not complete user testing after engineering evaluations revealed significant deficiencies. Service testing demonstrated that the YHO-2 had been the most capable, but due to a limited load capability, it was deemed not suitable to replace the OH-13.
Bureau of Weapons issued Technical Specification 153, a request for proposals (RFP) for a four-seat, turbine-powered, light observation helicopter capable of fulfilling various roles: personnel transport, escort and attack missions, casualty evacuation and observation. 25 aircraft manufacturers were solicited for the program on behalf of the Army Chief of Transportation. By January 1961, 12 manufacturers, including Cessna
, Hughes Tool Co. Aircraft Division
, Hiller Aircraft
and Bell Helicopters, had responded with 19 designs.
The United States Navy provided technical expertise to assist the Army in evaluating the design proposals. In October 1961, the Army selected three of the designs for a flight evaluation. Bell's D-250 design was recommended by the Army team and designated the YHO-4 (later YOH-4), Hiller's Model 1100
was recommended by the Navy team and became the YHO-5 (later YOH-5), and Hughes' Model 369 was added to the competition and became the YHO-6 (later YOH-6). Each manufacturer submitted 5 test and evaluation prototypes of their designs to the Army for flight test evaluation at Camp Rucker, Alabama
.
As a result of the flight evaluation, Hiller's YOH-5 and Hughes' YOH-6 were selected to compete in a program cost analysis bid for the contract. The Hughes bid won the contract, although Hiller protested the contract award, and in 1965, the YOH-6 was redesignated as the OH-6A Cayuse.
In 1967, the Army reopened the LOH competition for bids and Bell resubmitted for the program using their model 206A design. Fairchild-Hiller failed to resubmit their bid with the YOH-5A, which they had successfully marketed as the FH-1100. In the end, Bell won the contract and the model 206A was designated as the OH-58A. Following the Army's naming convention for helicopters, the OH-58A was named Kiowa for the Native American tribe.
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...
program to evaluate, develop and field a light scout helicopter to replace the Army's aging OH-13 Sioux. The program gained impetus with the advent of 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...
and was aided by advances in helicopter technology, specifically the development of the turboshaft
Turboshaft
A turboshaft engine is a form of gas turbine which is optimized to produce free turbine shaft power, rather than jet thrust...
engine. Three of the aircraft evaluated for the program would eventually enter military service, one as a training helicopter and two as observation helicopters used for battlefield 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....
missions.
History
In July 1953, the Office of Lieutenant GeneralLieutenant General (United States)
In the United States Army, the United States Air Force and the United States Marine Corps, lieutenant general is a three-star general officer rank, with the pay grade of O-9. Lieutenant general ranks above major general and below general...
John Dahlquist, Chief, Army Field Forces (AFF), forwarded desirable military characteristics for a two-place reconnaissance helicopter to Army Headquarters. Nearly a year later, in May 1954, Dahlquist's office once again emphasized the need for replacement aircraft and recommended procurement of troop test quantities of the YH-32
YH-32 Hornet
|-See also:-References:* Display information at Museum of Flight in Seattle, Washington* "The First 100 Years of Aviation"-External links:* * *...
. Preliminary evaluation of the YH-32 design revealed that the aircraft was unsuitable for the mission, and the tests were canceled.
In 1955, the Army Field Forces were transformed into the Continental Army Command (CONARC). Dahlquist, who had been promoted to 4-star General on 18 August 1954, continued in command. On 11 October 1955, CONARC recommended that the Department of the Army initiate a program to develop a replacement observation helicopter for the aging OH-13 Sioux and OH-23 Raven. Army's Chief of Research and Development agreed to include the requirement for a new helicopter in the budget for fiscal year 1957 on 19 March 1956, after CONARC highlighted the continued lack of development for replacement aircraft.
During the course of the next three years, three helicopters would be evaluated as candidates to replace the OH-13 and OH-23; the Sud-Ouest Djinn
Sud-Ouest Djinn
|-See also:-References:* The Illustrated Encyclopedia of Aircraft , 1985, Orbis Publishing, Page 2975- External links :* rare photo of the single seat SO.1220 that tested the power concept -- ie bottom of page 128**...
, the Hughes 269
TH-55 Osage
The Hughes TH-55 Osage was a piston-powered light training helicopter produced for the United States Army. It was also produced as the Model 269 family of light utility helicopters, some of which were marketed as the Model 300...
, and the Brantly B-2
Brantly B-2
-See also:-References:Bibliography*Taylor, John W.R.. Jane's All The World's Aircraft 1976-77. London:Jane's Yearbooks, 1976. ISBN 0-354-00538-3.-Further reading:...
. The aircraft were designated the YHO-1 DJ, YHO-2 HU, and YHO-3 BR, respectively. By October 1958, service testing of Sud Aviation YHO-1 DJ was completed. The following year saw the completion of the desert and temperate temperature testing of the YHO-2 HU. The YHO-3 BR did not complete user testing after engineering evaluations revealed significant deficiencies. Service testing demonstrated that the YHO-2 had been the most capable, but due to a limited load capability, it was deemed not suitable to replace the OH-13.
LOH
On 14 October 1960, the United States NavyUnited States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
Bureau of Weapons issued Technical Specification 153, a request for proposals (RFP) for a four-seat, turbine-powered, light observation helicopter capable of fulfilling various roles: personnel transport, escort and attack missions, casualty evacuation and observation. 25 aircraft manufacturers were solicited for the program on behalf of the Army Chief of Transportation. By January 1961, 12 manufacturers, including Cessna
Cessna
The Cessna Aircraft Company is an airplane manufacturing corporation headquartered in Wichita, Kansas, USA. Their main products are general aviation aircraft. Although they are the most well known for their small, piston-powered aircraft, they also produce business jets. The company is a subsidiary...
, Hughes Tool Co. Aircraft Division
Hughes Helicopters
Hughes Helicopters was a major manufacturer of military and civil helicopters from the 1950s to the 1980s.The company began in 1947, as a unit of Hughes Aircraft, then was part of the Hughes Tool Company after 1955. It became the Hughes Helicopter Division, Summa Corporation in 1972, and was...
, 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 Bell Helicopters, had responded with 19 designs.
The United States Navy provided technical expertise to assist the Army in evaluating the design proposals. In October 1961, the Army selected three of the designs for a flight evaluation. Bell's D-250 design was recommended by the Army team and designated the YHO-4 (later YOH-4), Hiller's Model 1100
Fairchild Hiller FH-1100
|-See also:-External links:* , current Type Certificate holder.* *...
was recommended by the Navy team and became the YHO-5 (later YOH-5), and Hughes' Model 369 was added to the competition and became the YHO-6 (later YOH-6). Each manufacturer submitted 5 test and evaluation prototypes of their designs to the Army for flight test evaluation at Camp Rucker, Alabama
Fort Rucker
Fort Rucker is a U.S. Army post located mostly 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 base for Army Aviation and is home to the United States Army Aviation Center of Excellence and...
.
As a result of the flight evaluation, Hiller's YOH-5 and Hughes' YOH-6 were selected to compete in a program cost analysis bid for the contract. The Hughes bid won the contract, although Hiller protested the contract award, and in 1965, the YOH-6 was redesignated as the OH-6A Cayuse.
In 1967, the Army reopened the LOH competition for bids and Bell resubmitted for the program using their model 206A design. Fairchild-Hiller failed to resubmit their bid with the YOH-5A, which they had successfully marketed as the FH-1100. In the end, Bell won the contract and the model 206A was designated as the OH-58A. Following the Army's naming convention for helicopters, the OH-58A was named Kiowa for the Native American tribe.
See also
- Bell YOH-4Bell YOH-4|-See also:-References:* Spenser, Jay P. "Bell Helicopter". Whirlybirds, A History of the U.S. Helicopter Pioneers. University of Washington Press, 1998. ISBN 0295980583.-External links:*...
- Fairchild Hiller YOH-5Fairchild Hiller FH-1100|-See also:-External links:* , current Type Certificate holder.* *...
- OH-6 Cayuse
- OH-58 KiowaOH-58 KiowaThe Bell OH-58 Kiowa is a family of single-engine, single-rotor, military helicopters used for observation, utility, and direct fire support. Bell Helicopter manufactured the OH-58 for the United States Army based on the 206A JetRanger helicopter. The OH-58 has been in continuous use by the U.S...
- HAL Light Observation HelicopterHAL Light Observation Helicopter-External links:* *...