Stinson L-1 Vigilant

The Vigilant was created in response to a 1938 United States Army Air Corps design competition for a two-seat, unarmed, short-range, light observation aircraft. Common folklore suggests that the demonstration of a Fieseler Storch at the 1938 Cleveland Air Races was the impetus for this, but that story has been proved false by current research.

In September 1937, a Storch was demonstrated in a competition with auto gyros at the 4th International Air Meet in Zurich, Switzerland and several highly placed American officials were in attendance, including the American military attache to France, observers from the Office of Naval Intelligence, and the European representative of the National Advisory Committee on Aeronautics, John J. Ide. The following month, Charles Lindbergh was invited to fly the Storch while on a tour of German aircraft factories. Reports from all these men were forwarded to the War Department in Washington and a development program for a similar aircraft was initiated. The program was approved in January, 1938, the design and performance specifications drawn up in February, and a design competition was approved in April by the Adjutant General. Circular Proposal CP-39-2, inviting competitive bids from aircraft manufacturers, was released on August 15, 1938, two weeks prior to a demonstration of the Fi 156 Storch at the 1938 Cleveland Air Races. While that event caused quite a stir in both American military and public aviation circles, very few realized that a program was already quietly underway to develop such an aircraft.

Stinson won the $1.5 million contract with an initial order for 100 aircraft. Eleven competing designs included the Bellanca YO-50 and Ryan YO-51 Dragonfly that were each runners-up and garnered 3-plane contracts for further evaluation.[2] The Stinson Model 74 was a radial-engined, high-wing monoplane with large trailing-edge slotted flaps and full-span leading-edge automatic slats for low-speed, high-lift, short-field performance. The movable slats had been invented by the Handley Page company in the 1920's. The Model 74 prototype was given the Army designation YO-49 for evaluation, with the first flight by test pilot Al Schramm on 15 July 1940.[3]

The aircraft was built of chrome-molybdenum steel tubing and covered with doped cotton fabric; the engine cowling and the fuselage, forward of the wing, was fully enclosed in aluminum. Control surfaces and the empennage were fabric-covered stainless steel. The Lycoming power plant was hand-cranked with an inertial starter and was fitted with a Hamilton Standard constant speed propeller. At least 12 ambulance conversions were fitted with Edo 49-4000 floats (4,000-pound displacement)[4] for amphibious landings and takeoffs.[3]

The Vigilant could maintain stable, level flight at 31 miles per hour and in a 20 mph breeze it was capable of stopping in less than its own length. Given an adequate headwind, it gave the illusion of "hovering" and sometimes surprised onlookers by drifting backward. Under calm conditions the L-1 could land and take off again inside a 200 foot diameter circle, and landing over a 50-foot obstacle it could stop on dry sod within 300 feet with a ground roll of approximately 100 feet.[2]

1941 L-1, Reserve Grand Champion, AirVenture 2016

Ex-USAAC O-49 Vigilant in the Weeks Museum at Tamiami, Florida, in 1989 wearing RAF-style markings

The Stinson Vigilant was used in diverse roles such as towing training gliders, artillery spotting, liaison, emergency rescue, transporting supplies and special espionage flights.[5] Another contract was later awarded for the O-49A which had a slightly longer fuselage and other equipment changes. In April 1942 the aircraft were redesignated the L-1 and L-1A (liaison). Up to 17 L-1 and 96 L-1A aircraft were allocated to the British Royal Air Force under the Lend-Lease Act, with varying numbers given for aircraft actually delivered (see Variants, below). The RAF designated the aircraft the Vigilant Mk I and Vigilant Mk II respectively. General Harry Crerar, Commander of the First Canadian Army in Europe during World War II, maintained a Vigilant for his personal use.

Aircraft were modified for a variety of roles including as an ambulance aircraft. No further production orders were placed as the aircraft was superseded by procurement of vast numbers of both the militarized Piper J-3 Cub, the L-4 Grasshopper (in addition to Aeronca's and Taylorcraft's similar conversions), and Stinson's own L-5 Sentinel, itself produced in nearly 4,000 examples; were all generically classified as "puddle-jumper" aircraft.

A Vigilant was modified in 1943–1944 for experiments in boundary layer control.[6]

O-49 Vigilant at Patterson Field during World War II

Stinson Model 74

company designation

O-49 Vigilant

U.S. Army designation for first production batch, 142 built.[4]

L-1 Vigilant

1942 redesignation of O-49.[4]

O-49A Vigilant

Fuselage lengthened 13 in (33 cm)[7] 182 built.

O-49B Vigilant

Conversion to ambulance variant, three or four[8] converted.

L-1A Vigilant

1942 redesignation of O-49A.[4]

L-1B Vigilant

1942 redesignation of O-49B.[4]

L-1C Vigilant

L-1A ambulance variant, 113 converted.[8]

L-1D Vigilant

L-1A training glider tug, 14 to 21[8] converted.

L-1E Vigilant

L-1 amphibious ambulance variant, seven converted.[4]

L-1F Vigilant

L-1A amphibious ambulance variant, five conversions.[4]

Vigilant Mk I

RAF designation of L-1, 14[8] to 17 allocated by Lend Lease

Vigilant Mk II

RAF designation of L-1A, 96 allocated, circa 13 to 54[8] delivered

CQ-2 Vigilant

US Navy conversion of L-1A to target control aircraft, one or more[8] converted

 United Kingdom

• Royal Air Force

 United States

• United States Army Air Corps

Airworthy

• 40-3102 – operated by the Fantasy of Flight in Polk City, Florida.[9][10][11] This aircraft flew for the first time after restoration on 18 July 2013.[12]
• 41-18915 – operated by the Alaska Aviation Heritage Museum in Anchorage, Alaska.[13][14][15]
• 41-19031 – privately owned and operated in Blaine, Minnesota.[16][17]

On Display

• 41-19039 – National Museum of the United States Air Force in Dayton, Ohio.[18]

Under restoration or in storage

• 40-0283 – under restoration by G & P.M. Turner in London.[19]
• 40-3141 – in storage at the United States Army Aviation Museum at Fort Rucker, Alabama.[20]

Data from American Warplanes of World War II[21]

General characteristics

• Crew: 3
• Length: 34 ft 3 in (10.44 m)
• Wingspan: 50 ft 11 in (15.52 m)
• Height: 10 ft 2 in (3.10 m)
• Wing area: 329 sq ft (30.6 m²)
• Empty weight: 2,670 lb (1,211 kg)
• Max takeoff weight: 3,400 lb (1,542 kg)
• Powerplant: 1 × Lycoming R-680-9 9-cylinder air-cooled radial piston engine, 295 hp (220 kW)
• Propellers: 2-bladed fixed-pitch propeller

Performance

• Maximum speed: 122 mph (196 km/h, 106 kn)
• Range: 243 mi (391 km, 211 nmi)
• Service ceiling: 12,800 ft (3,900 m)
• Rate of climb: 408 ft/min (2.07 m/s)
• Wing loading: 10.3 lb/sq ft (50 kg/m²)
• Power/mass: 0.0867 hp/lb (0.1425 kW/kg)

Aircraft of comparable role, configuration, and era

• Bellanca YO-50
• Fieseler Fi 156 Storch
• Miles Messenger
• Polikarpov Po-2
• Repülőgépgyár Levente II
• Ryan YO-51 Dragonfly
• Westland Lysander

Related lists

• List of aircraft of the Royal Air Force
• List of aircraft of World War II
• List of military aircraft of the United States

Wikimedia Commons has media related to Stinson L-1 Vigilant.

• Vultee L-1A Vigilant, National Museum of the United States Air Force
• Stinson O-49 on aerofiles