OH-1 / L-19 Bird Dog
In 1950, the Army sought a military light plane to replace the World War II L-4, L-5 and L-16 aircraft. Cessna competed with a modification of their civilian Model 170. By mid-summer, Cessna was awarded the initial contract for 418 of the newest and first ever all-metal, high-flying observation plane.
In late 1949 and early 1950, the Navy's "Revolt of the Admirals" had just ended, p. 31) and the Korean War had just begun. Public aviation attention was focused on new jet fighters, research aircraft and supersonic flight, as well as new helicopters. The post-WW II heyday of private flying had ended, and Cessna, with its range of high-wing, all-metal models, was one of the few surviving light plane manufacturers.
Largely unnoticed among higher profile events, a competition for a new all-metal, light, two-place Army liaison airplane was being conducted jointly by the Army and Air Force. The competition featured a prototype fly-off in spring 1950 which included both Air Force technical and Army operational user evaluations. Cessna beat the other light aircraft manufacturers who entered prototypes and received a contract for 418 L-19As in June 1950 as Korean combat started.
Using components from Cessna's civilian models and adapting such company special features as single-piece spring-steel landing gear, the redesigned fuselage incorporated an extended-vision cabin for pilot and observer in tandem. A single rack for a rocket or small bomb could be mounted under each wing outboard of the wing strut attachment.
Cessna exceeded competitors' as well as the Army's required capabilities, and the aircraft became the L-19 Bird Dog. Specific qualities such as short distance take-offs and landings, and low maintenance requirements quickly made it a popular commodity in the Korean Conflict. The key alteration from the civilian Cessna Model 170, was the all-window cockpit, including panels in the wing overhead. This gave the pilot greater vision for observation missions.
The Army accepted some 3,430 0-1A's and E's by March 1964 with the USMC using 0-1B's and 0-1C's. Later, the USAF utilized F's and G's in Vietnam for forward air controller missions. Nineteen other countries also purchased this versatile aircraft. The Army finally discontinued the L-19 in 1974 after 24 years service.
The structurally stronger T0-1D served as the Army's instrument trainer version in having a variable pitch propeller and an instrument panel in the rear. The latter could be enclosed for hooded flight.
The Cessna L-19 Bird Dog was used in both the Korean and Vietnam Wars as a liaison aircraft and forward air controller (FAC). Powered by a 213-horsepower, air-cooled Continental engine, the Bird Dog was easy to fly and reliable.
The L-19s were assigned a large variety of missions. They were very limited on cargo space and could only accommodate a pilot and one passenger. However, it did not limit their capabilities in the area of reconnaissance, aerial photography and artillery spotting. With slight modifications, the Bird Dogs performed additional tasks such as cargo drops, laying communication wires and medical evacuation, accommodating one stretcher.
The Bird Dog had an impressive ability to takeoff and land in short distances. Many L-19s were fitted with large all-terrain landing wheels so they could land in many of the forward combat zones that did not support major airstrips. Others had skids placed on them for landing on snow and ice. Though its cargo capacity was much lower than most other aircraft, its ease of maneuverability within the field of battle still proved to be a transportation asset.
The drawbacks of the L-19 created a few problems. First, the L-19 lacked armor protection. The small 6-cylnder engine did not have sufficient horsepower to fly a thick armored airframe, nor could it produce speeds to outmaneuver other aircraft or ground fire. Standard rifle fire cost the lives of many skilled pilots. It also did not have self-sealing fuel tanks which made it vulnerable to ground fire. And it's low capacity for cargo limited the number of flare rockets it could carry.
By December 1950, Marine observation squadron VMO-6 with its mixed complement of helicopters and OY Sentinels was working with ground Marine units in Korean combat, and the first production L-19 Bird Dogs were entering similar service in support of Army ground troops. Just as the Marines had favorably assessed the WW II Army "Grasshoppers" and obtained L-5s from Army production as OYs, the Marines selected the Army L-19s in 1951 to replace aging OYs, and subsequently procured a total of 60 as OE-1s.
Bird Dogs participated in their first combat engagements during the second liberation of Seoul on 18 March 1951. Army aviators were quick to appreciate the added safety and improved performance over the fabric-covered, heater-less L-4s, L-5s and L-19s with which they had begun the war.
In February 1952, an L-19 was hit by enemy anti-aircraft fire at an altitude of 6,000 feet. Twelve feet of the right wing was shot off but the pilot and observer regained control and miraculously landed the aircraft. Within three hours, a new right wing had been installed and the pilot was able to fly it once again.
In spring, Korea was plagued with hordes of biting flies that made life miserable for the forward-based Army troops. In April 1952, a 2nd Division aviator and a mechanic rigged an L-19 with a crude spray rig - a 20-gallon drum filled with DDT and tubes running from the drum to the exhaust stacks. The hot exhaust atomized the mixture into a fog that drifted down over the area to kill the flies, making life a little less miserable.
An additional 25 were ordered by the Marines in 1952. However, OE-1 operations showed performance limitations, particularly at elevated terrain levels. The helo was also particularly vulnerable to ground fire. To correct these problems, an upgraded model included crew armor protection, increased wing rocket or bomb carriage capability and a supercharged engine. Again, Cessna used wings and tail surfaces from commercial production designs for the new OE-2. Correction of engine installation deficiencies and extended flight testing delayed deliveries until after the 1953 Korean armistice, and there was no further OE-2 production.
For the rest of the 1950s, the three VMO squadrons operated mixed inventories of OE-1s and -2s, with helicopters taking over more of the "low and slow" support functions both in the U.S. and the western Pacific area. Carrier operations were authorized and individual OEs operated from a number of carriers as Marines explored various approaches to expeditionary operations. A few OE-1s were procured either for the Marines or for foreign air forces as military assistance, but the Army handled almost all further Bird Dog procurement. While OE peacetime attrition was low, the operating inventory continued to decrease.
Airplane enthusiasts generally remember 1962 as the year that the Department of Defense established joint service designations for all military aircraft. Both Army L-19s and Marine OEs were folded into the new O-1 model, and OE-1s and OE-2s became O-1Bs and O-1Cs, respectively. For the Marines and their remaining OEs, two 1962 events were significant. A Marine helicopter transport squadron, with a few Bird Dogs for liaison duties, was deployed to Vietnam as part of the U.S military assistance program for the South Vietnamese. Back home, a new turboshaft engine-powered Bell helicopter, to be delivered as the UH-1E, was ordered. It would take over the O-1's VMO roles as part of its mission. Like the OE-1 originally, it was adapted from Army production.
As US military involvement in Vietnam expanded, especially as it became a full-fledged war beginning in 1964, O-1 activities were adapted to the widespread warfare. Army and Air Force units found their O-1s to be ideal forward air controller (FAC) aircraft supporting ground force combat, particularly in limited arms jungle fighting, and the South Vietnam air force used its O-1s similarly. FACs would spot and mark targets with the O-1s' smoke rockets for destruction by attack aircraft.
Initially, the Marines preferred to use their VMO squadron helicopters for this purpose, but by 1967 the effectiveness of the O-1s for Marine ground fire support was recognized and VMO-6 began using O-1Cs in combat. Eight O-1Gs (Army O-1As modified for FAC use) were obtained to augment the remaining O-1Cs.
Most light observation planes like the L-19 Bird Dog fell back under US Air Force control in 1965. The L-19 continued use throughout the Vietnam conflict, redesignated as the O-1, and was found useful in tactical air support.
As the ground war intensified with more effective North Vietnamese weapons, the need for attack-capable FAC aircraft was met with armed UH-1Es and new joint service short-takeoff-and-landing OV-10s. Marine O-1 combat losses were not replaced, and by 1969 O-1s were being withdrawn from Vietnam. The last Marine Bird Dogs were transferred to Futenma, Okinawa, and retired there in 1970.
Later, one special flight closed out Naval Aviation's ties to the O-1. On 30 April 1975, as US personnel were being evacuated from Saigon to carriers offshore, a South Vietnamese Air Force major boarded his wife and five children into a Vietnamese Bird Dog and flew out toward the carriers receiving helicopter-delivered evacuees. Spotting Midway (CV 41), and with his fuel tanks almost empty, he requested permission to land by means of dropping a note onto the deck as he circled above. After the deck had been cleared he was given permission to land by means of an interpreter over the radio. Without assistance of a tail hook or a barrier, the South Vietnamese pilot made a slow approach to a successful landing, becoming the first Bird Dog to land on a carrier deck. Their airplane is now on display at the National Museum of Naval Aviation, Pensacola, Fla., to recognize the unusual event.
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