Stinson L-1 Vigilant

https://en.wikipedia.org/wiki/Stinson_L-1_Vigilant

The Stinson L-1 Vigilant (company designation Model 74) was a 1940s American
light observation aircraft built by the Stinson Aircraft Company at Wayne,
Michigan (by November 1940 a division of Vultee Aircraft Corporation). The
aircraft was operated by the United States Army Air Corps as the O-49 until
1942.

The Vigilant was designed in response to a 1938 United States Army Air Corps
design competition for a two-seat light observation aircraft. When the
German-manufactured Fieseler Storch was demonstrated at the Cleveland Air Races,
the Air Corps revised its specifications in an attempt to match the performance
of the Storch. Stinson (later a division of Vultee), won the $1.5 million
contract over 11 competitors, including the Bellanca YO-50 and Ryan YO-51
Dragonfly.

The Model 74 was a single radial engined high-wing monoplane with trailing-edge
high-lift devices for low speed and high lift performance. The prototype
aircraft was built full-span leading-edge automatic slots manufactured by
Handley Page, and slotted flaps. The Model V-74 was given the Army designation
YO-49 for evaluation, with the first flight by test pilot Al Schramm on 15 July
1940.

The aircraft was built of steel tubing and fabric, with the fuselage forward of
the wing enclosed in sheet metal. Control surfaces and the empennage were
fabric-covered stainless steel. The Lycoming power plant was hand-cranked
inertia starting, and was fitted with a Hamilton Standard constant speed
propeller. At least 12 ambulance conversions were fitted with Edo 49-4000
pontoons (4,000-pound displacement) for amphibious landings and takeoffs.

The Vigilant was capable of stopping in less than its own length, and could
maintain stable flight at 31 miles per hour. Anecdotally, the Vigilant was said
to be capable of backwards flight in a strong headwind.


Role
Light Observation, Liaison

Manufacturer
Stinson Aircraft Corporation

Designer
A.P. Fontaine

First flight
15 July 1940

Introduction
1941

Primary users
United States Army Air Corps
Royal Air Force

Number built
324

The Stinson Vigilant was used in diverse roles such as towing training gliders,
artillery spotting, liaison, emergency rescue, transporting supplies and special
espionage flights. 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 the L-5 Sentinel and L-4
Grasshopper "puddle-jumper" aircraft.

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

Specifications (L-1A)

General characteristics
Crew: 3
Length: 34 ft 3 in (10.44 m)
Wingspan: 50 ft 11 in (15.52 m)
Height: 10 ft 2in (3.10 m)
Wing area: 329 ft² (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 radial piston engine, 295 hp (220 kW)

Performance
Maximum speed: 106 knots (122 mph, 196 km/h)
Range: 243 nm (280 mi, 451 km)
Service ceiling: 12,800 ft (3,900 m)
Rate of climb: 408 ft/min (124.36 m/min)
Wing loading: 10.3 lb/ft² (50.4 kg/m²)
Power/mass: 0.0867 hp/lb (0.143 kW/kg)



*