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OY-1 Sentinel

Aircraft Details
& Specifications

Manufacturer: Stinson Aircraft Division, Consolidated-Vultee Aircraft 

Type: Observation/liaison 

Bureau number: Serial numbers 42-14893 and 42-14918 (aircraft built from two USAAF L-5 wrecks) 

Year delivered: 1943



Length: 24 ft, 1 in 

Wing Span: 34 ft

Height: 7 ft, 11 in


Max Speed: 110 kts (127 mph) 


Ceiling: 15,800 ft

Range: 375 nm (no reserve) 

Powerplant: One 185 hp Lycoming 0-435-1 six-cylinder, horizontally opposed air-cooled engine




Crew: Pilot and observer

The OY-1 was originally built by the Stinson Division of Consolidated Váltee as the commercial Model 105 "Voyager". Following the outbreak of war, the "Voyager" was redesigned to meet the role of a military liaison aircraft. Originally produced for the US Army Air Force and renamed ""Sentinel"", the L-5 is a single-engine, two-place, high-wing design, with a fabric covered aluminum and wood frame. The L-5 was used for general liaison, light transport, artillery spotting and medical evacuation.

The Marine Corps acquired 306 L-5s and designated them as the OY-1. The first aircraft was delivered on January 11, 1943, with deliveries continuing through August 1945. In early 1944, four artillery spotting squadrons were reorganized into Marine Observation Squadrons (VMOs) 1 through 4, each to serve with a Marine combat division. VMOs 2 and 4 were first to participate in a major island invasion, flown ashore from escort carriers (CVE) on D-day plus 2 onto Saipan in June 1944.

Through the remainder of the Pacific island campaigns, OY-1s were at the heart of the battles. In preparation for the Iwo Jima invasion, VMOs 4 and 5 experimented with launches from tank landing ships (LST) using a device called the Brodie gear, but aircraft losses due to ship rolling and other difficulties terminated this experiment.

The use of OY-1's for casualty evacuation was a high priority. Army experience had previously recognized this use so subsequent models of the L-5 (B through G) had a boxy rear fuselage and revised rear cabin door, accommodating a stretcher patient aft of the cabin. Regardless of the Army model, all Marine Corps aircraft were designated OY-1s. V-J Day saw the OYs continue to operate with Marine ground troops as they took up their occupation duties in Japan and postwar activities in Guam and China, After WWII, the OY-1 served with distinction in the Korean War and continued in active service with the USMC until at least November 1954.

This aircraft is on loan from the National Museum of the Marine Corps.

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