THE CESSNA O-1 ‘BIRD DOG’
submitted by: Alva Leon Matheson
In the late 1940s the US Army saw the need for a new observation and liaison aircraft which (based on wartime experiences) would be free of the shortcomings of earlier aircraft. As a result, a specification for an all metal, two seat observa- tion and liaison monoplane was circulated to US light aircraft manufacturers. Cessna’s submission, the Model 305A, was declared the winner and an initial contract for 418 aircraft was awarded on May 29, 1950. Powered by a 213 hp Continental O-470-11 engine, the 305A was a strut braced, high wing, lightweight mono-plane based on the Model 170. It differed from the 170 by having the aft fuselage lowered so a rear window could be added. Transparent panels were installed in the cockpit roof and the fuselage narrowed from the top giving a good downwards view. A wider access door enabled the loading of a standard stretcher for which support brackets were installed. Steel spring landing gear reduced the chances of a ground loop and made operation from rough fields possible. Slotted high lift flaps were fitted along the trailing edge of each wing increasing performance during short field landings and slow flight (the aircraft could takeoff and land over a 50 foot obstacle in as little as 167 yards). Deliveries to the US Army, who gave it the designation L-19A, began in December 1950. The aircraft’s more common name, “Bird Dog”, was chosen by General Mark Clark following a competition held among Cessna workers. It is believed that the winning worker won $200 cash, a week off work on full pay and rides for four people in any Cessna aircraft.
The outbreak of the Korean War on June 25, 1950 saw production of the Bird Dog increase dramatically and on February 16, 1951 it was pressed into service in the conflict. During the war, the Bird Dog earned the nickname “jeep with wings” due to the multitude of tasks that were assigned to it. Not only was it used for the obvious roles of artillery spotting and as an observation platform for commanders in the field, but also for such diverse missions as evacuating wounded, laying communications wire and dropping supplies and flares. By 1954, 2,486 Bird Dogs had been delivered, 60 were diverted to the US Marine Corps where they were re- designated the OE-1. A dual control instrument training version, the L-19A-IT, was developed in 1953. This version had blind flying curtains and full instrumentation fitted to the rear cockpit and was followed by the constant speed propeller equipped TL-19D trainer in 1956. The final production version of the Bird Dog was the 1957 L-19E which featured a strengthened airframe as well as other detail changes. 1962 saw the US Military adopt the Tri-Service designation system (which is still used today) and as a result the designation of all the Bird Dogs still in active service was changed. The L-19A, TL-19D and L-19E became the O-1A, TO-1D and O-1E respectively while the USMC OE-1 became the O-1B.
The war in Vietnam saw the Bird Dog assigned a new mission, that of Forward Air Control. The US Air Force acquired many TO-1Ds and O-1As which were modified for the FAC role by the addition of under wing hardpoints, a VHF radio and (in the case of the TO-1D) the removal of the rear controls. Not surprisingly, the modified USAF Bird Dogs received new designations with the TO-1D becoming O-1F and the O-1A becoming the O-1G. The US Army also undertook FAC missions, initially using helicopters. However, early combat experience saw them revert back to fixed wing aircraft and borrow a number of Bird Dogs from the Air Force. Forward Air Control missions in Vietnam usually involved having attack aircraft circling at high altitude while an FAC Bird Dog would fly low and slow over a specific area as the crew looked for enemy activity. If ground targets were spotted they would mark them, normally with white phosphorus or smoke rockets, and call in the waiting fighter-bombers. Following the attack, the Bird Dog remained on the scene to report the results and, if necessary (or possible), call in another strike.
As can be imagined, these missions began to take their toll on the Bird Dog. The low altitude and slow speeds involved combined with a lack of armour or self sealing fuel tanks made the aircraft an easy target for even small arms fire from the ground. As a result they eventually started being replaced from 1967 onwards by the bigger, and more powerful, Cessna O-2 and North American OV-10 Bronco. Consequently, a large number of Bird Dogs were assigned to the
South Vietnamese Air Force, one of which was to achieve limited fame during the evacuation of all US military forces from Saigon in 1975. A South Vietnamese Air Force major squeezed his wife and five children into the cockpit of a Bird Dog and took off from Con Son Island. With his fuel running low, the major spotted the aircraft carrier USS Midway and dropped a note requesting permission to land. The deck was cleared and a Vietnamese interpreter communicated with the major by radio. He made a slow approach and successful landing despite the fact that, not only had he never landed on an aircraft carrier before, he had never even seen one.
By the time production ceased in 1964, some 3,431 Bird Dogs had been built. As well as the US military, where it was finally retired in the mid- 1970s, the aircraft was operated by the military forces of around 15 other countries. They were also built under license in Japan by Fuji Heavy Industries and 42 civilian versions were built new from surplus parts between 1962 and 1979 by the Ector Aircraft Company in Texas as the “Ector 305”.
SPECIFICATIONS
Power Plant: One 213 hp Continental O-470-11 flat-six.
Wingspan: 10.97 m (36 ft).
Length: 7.89 m (25 ft 10 in).
Max T-O weight: 1,103 kg (2,430 pound).
Max level speed: 184 km/h; 115 mph; 100 knots. Range: 848 km (530 miles).
PRACTICAL FLIGHT TEST RESULTS
Max speed in a dive: Real Fast. Afraid to look. Could not see it for the noise. I hope it zooms after this.
Max +ve g: Pull until the door pops open.
Text © 2002 Stuart Russell.