Excerpted from General Dynamics Aircraft and their Predecessors by John Wegg, 1990.

Further development by [A.P.] Fontaine of the Model 75, the tandem-seat military version of the Model 10 Voyager, resulted in the heavier Model 76 Sentinel with a larger fuselage and considerably higher operating weights yet the same 34ft span wing (of all-wood construction, as was the tail, to save strategic materials). The cabin was glazed aft and the enlarged side windows sloped outwards to improve vision, and a fuel tank was installed in each wing root instead of only on the right as in the Model 10.

The prototype (NX27772 msn 76-1) was fitted with a 175hp Lycoming and first flown by [Al] Schramm at Wayne [Michigan] on 28 June, 1941. An almost fatal spin test revealed that the full-span leading-edge slots provided asymmetric lift depending on direction of rotation and led to an uncontrollable flat spin. The problem was solved by using half-span slots, as on the Model 10, and slightly larger tail surfaces.

The result was a viceless and exceptional STOL aircraft with a capability of operating from and to 50ft in 630ft and orders for 3,608 followed from the Army for the following versions.

O-62-ST, 185hp O-435-1, 12-voIt electrical system, 275 built (42-14798/15072), redesignated L-5 during production. A further 1,538 (42-98036/99573) produced as the L-5-VU and L-5-VW. In 1962, any surviving aircraft were designated U-19A-VW.

USAAF L-5-VW 42-14879 (82nd production aircraft). -Convair

L-5B-VW, right-side downward opening hatch aft of observer’s door in deeper rectangular fuselage to enable loading of stretcher or 200lb of cargo, and provision for floats, 730 built from 1944 (42-16703/17252).

L-5C-VW, similar to L-5B with a K-20 camera installed, 200 built (44-17253/17452).

L-5D-VW, conversions to L-5C standard made from L-5s in service.

L-5E-VW, as L-5C but STOL capability was enhanced with 15-degree drooped ailerons operating in conjuction with the flaps. The L-5E-1 had larger brakes; 750 built (44-17453/ 18202).

XL-5F-VW, one aircraft only converted from an L-5B (44-17103) with a 24-volt electrical system and a different radio installation.

L-5G-VW, as XL-5F with a 190hp O-435-11, controllable-pitch propeller, radio changes, and maximum weight increases; 115 built (45-34911/35025) with another 785 cancelled.

Production ceased in November 1945, with 3,608 serials allocated. However, USAAF documents state that a total of 3,590 aircraft was delivered with the discrepancy in the L-5 and L-5E batches. In addition, 900 more aircraft on order were cancelled. The designation L-5A applied to a version with a 24-volt electrical system but all were cancelled. However, this change appeared on some later production aircraft.

Some 306 L-5/B/Es were transferred to the Navy/Marines as the OY-1 with new serials (BuA 02747/ 02788, 03862/04020, 60460/60507, 75159/75182, 120442/120474) and there were a further 152 transfers without renumbering. In December 1948, all OY-1s with a 24-volt electrical system were redesignated OY-2s. The OY Sentinel was used to establish direct support Marine observation squadrons and the final combat service of the OY-2 was with VMO-6 from August 1950 until April 1952 in Korea.

US Coast Guard OY-1 42-14870. -Cmdr Jess Barrow collection

The RAF took delivery of forty L-5s (Sentinel I, KJ368/407) and sixty L-5Bs (Sentinel II, KJ408/467) for use in Burma by No.194 Squadron. One USAAF aircraft (42-99129) was loaned to the RAAF and another was interned in Switzerland with the serial A-96.

OY-2 03877 Nasty Break # V of VMO-6 over North Korea in 1951. – US Navy

Undoubtedly the most widely used Allied utility aircraft, the Sentinel became known as the ‘Flying Jeep’ for its ability to go almost anywhere. Used widely in all theatres for communications, air observation, and casualty evacuation, some Marine OY-1s mounted a bazooka on the wing struts.

In 1948, NACA Langley Field modified L-5E 44-17939 with a five-blade paddle propeller driven at 1,000 rpm by an engine geared down in a ratio of 2.8 to 1, and a muffled exhaust. Noise was reduced from 99 decibels to 66 (a reduction of 90 per cent) but the extra weight made it an impractical conversion as a low-flying ‘stealth’ reconnaissance aircraft.

With the outbreak of the conflict in Korea, the L-5 was returned to service in its former roles. The USAF officially retired the type in 1953, but four years later acquired one additional L-5G (57-6278) as a glider tug for the Air Force Academy, it was redesignated U-19B-VW in 1962.

Stinson L-5B Sentinel II

At least one was used by the Indonesian Air Force and larger quantities were supplied to the air forces of Ethiopia, Greece, Japan, Republic of Korea, Mexico, the Philippines, Thailand, and Italy. Large numbers from the last source were passed to the Aero-club d’Italia in 1954. The other major civil user of the Sentinel outside the United States was India, with over 200 registered.

In the USA the Sentinel was certified under TCu 764 (17 December, 1945) and the remaining inventory of aircraft and spares at Wayne acquired by Sentinel Aircraft Inc, Dexter, Michigan. Possibly, further production was undertaken using the spares supply.

Several hundred were civilianised and Clevenger Aircraft converted several to biplanes for crop dusting from 1955 with the 220hp Continental W-670-16, clipped top wing and lower wing from a Piper Cub. Today, over one hundred and fifty L-5s of various types remain active in the United States and there are a few others still registered in Canada and overseas.

Clevenger L-5, N69083, c/n 76-017. -Geoff Goodall

L-5 Specifications

One 190 hp Lycoming O-435-A six-cylinder air-cooled opposed engine.
Span 34ft 0in; length 24ft 1in; height 8ft 11 1/2 in; wing area 155sq ft.
Weight empty 1,472lb; gross weight 2,185Ib.
Maximum speed 129mph, cruising speed 115mph; climb 975ft/min; ceiling 15,800ft; range 390 miles (36 US gal fuel capacity).

OY-2 Specifications

One 190hp Lycoming O-435-11 six cylinder air-cooled opposed engine.
Weight empty 1,600Ib; gross weight 2,265Ib.
Maximum speed 126.5mph at sea level; climb 900ft/min; ceiling 15,600ft; range 357 miles.

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