Stinson L-1 Vigilant

Summary

The Stinson L-1 Vigilant (company designation Model 74) was an American liaison aircraft designed by the Stinson Aircraft Company of Wayne, Michigan and manufactured at the Vultee-Stinson factory in Nashville, Tennessee (in August 1940 Stinson became a division of Vultee Aircraft) Corporation).[1] The aircraft was operated by the United States Army Air Corps (later Army Air Forces), and Army Ground Forces as the O-49 until April 2, 1942 after which the liaison category of airplanes was established and the designation changed to L-1.

L-1 (O-49) Vigilant
Vultee L-1A Vigilant USAF.jpg
Role Light Observation, Liaison
Manufacturer Stinson Aircraft Corporation
Designer A.P. Fontaine[citation needed]
First flight 15 July 1940
Introduction 1941
Primary users United States Army Air Corps
Royal Air Force
Number built 324

Design and developmentEdit

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]

Operational historyEdit

 
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]

VariantsEdit

 
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

OperatorsEdit

  United Kingdom
  United States

Surviving aircraftEdit

Airworthy
On Display
Under restoration or in storage

Specifications (L-1A)Edit

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)

See alsoEdit

Aircraft of comparable role, configuration, and era

Related lists

ReferencesEdit

NotesEdit

  1. ^ Eden and Moeng 2002, p. 1100.
  2. ^ a b Sentinel Owners & Pilots Association,2021, L-5 History Blog #17.
  3. ^ a b Merriam 2002, p. 26.
  4. ^ a b c d e f g Merriam 2002, p. 27.
  5. ^ Adcock 2005, p. 7.
  6. ^ "Money-box Slottery." Flight, 4 August 1949, p. 124.
  7. ^ "Vultee L-1A Vigilant." National Museum of the United States Air Force, 17 April 2009.
  8. ^ a b c d e f "Stinson O-49." Aerofiles, 17 April 2009.
  9. ^ "1941 Stinson Vultee L-1E". Fantasy of Flight. Fantasy of Flight. Retrieved 13 August 2016.
  10. ^ "Airframe Dossier – Stinson L-1 Vigilant, s/n 40-3102 USAAF, c/r N63230". Aerial Visuals. AerialVisuals.ca. Retrieved 13 August 2016.
  11. ^ "FAA Registry: N63230." faa.gov Retrrieved: 16 August 2021.
  12. ^ "Fantasy of Flight's Stinson L-1 Flew Today!". Warbirds News. Warbirds News. Retrieved 13 August 2016.
  13. ^ "1941 STINSON L-1". Alaska Aviation Museum. Alaska Aviation Museuma. Retrieved 12 February 2020.
  14. ^ "Airframe Dossier – Stinson L-1F Vigilant, s/n 41-18915, c/r N1ZS". Aerial Visuals. AerialVisuals.ca. Retrieved 13 August 2016.
  15. ^ "FAA Registry: N1ZS." faa.gov Retrieved: 16 August 2021.
  16. ^ "Airframe Dossier – Stinson L-1 Vigilant, s/n 41-19031 USAAF, c/r N1377B". Aerial Visuals. AerialVisuals.ca. Retrieved 13 August 2016.
  17. ^ "FAA Registry: N1377B." faa.gov Retrieved: 16 August 2021.
  18. ^ "Vultee L-1A Vigilant". National Museum of the US Air Force. Retrieved 13 August 2016.
  19. ^ "Airframe Dossier – Stinson L-1 Vigilant, s/n 40-283, c/r GCIGB". Aerial Visuals. AerialVisuals.ca. Retrieved 12 February 2020.
  20. ^ "Airframe Dossier – Stinson L-1B Vigilant, s/n 40-3141, c/r 79". Aerial Visuals. AerialVisuals.ca. Retrieved 12 February 2020.
  21. ^ Donald 1995, p. 236.

BibliographyEdit

  • Adcock, Al. US Liaison Aircraft in action (Aircraft in Action: No. 195). Carrollton, Texas: Squadron/Signal Publications, 2005. ISBN 978-0897474870.
  • Donald, David (ed.). American Warplanes of World War II. London: Aerospace Publishing, 1995. ISBN 1-874023-72-7.
  • Eden, Paul and Soph Moeng (eds.). The Complete Encyclopedia of World Aircraft. London: Amber Books Ltd., 2002. ISBN 0-7607-3432-1
  • Gray, James H. L-5 History Blog #17 (2021), and notes from the Wright Field Liaison Program papers at the National Archives. www.sentinelclub.org.

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  • Ogden, Bob. Aviation Museums and Collections of North America. Tonbridge, Kent, UK: Air-Britain (Historians ) Ltd, 2007. ISBN 0-85130-385-4.
  • The Illustrated Encyclopedia of Aircraft (Part Work 1982–1985). London: Orbis Publishing, 1985.

External linksEdit

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