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Avion Experimental No.1 (Northrop) “N” Listings Northrop Alpha 3

Northrop Alpha 2
Single-engine seven-seat closed cabin land monoplane

Archive Photos

Northrop Alpha 2 (3600x2400 pixel 3-view drawing by Skytamer.com)

Northrop Alpha 2 (NC11Y, c/n 2, mfg 11/1930) on display at the National Air & Space Museum, Washington, DC (2/20/2004 photo by Jim Hough)

Northrop Alpha 2 (NC999Y, c/n 4) (Historic photo from the NASA Langley Research Center Photo Collection)

Northrop Alpha 2 (NC942Y, c/n 6) (Historic photo by Northrop Aircraft from the Skytamer Archive)

Overview

Northrop Alpha 2
Type: Single-engine seven-seat closed cabin land monoplane.
Original Engine: 1 x 420 to 450-hp Pratt & Whitney Wasp "C"
Wing span: 41 ft 10 in
Wing area: 295 ft²
Length: 28 ft 5 in
Height: 9 ft 0 in
Weight empty: 2,679 lbs
Weight gross: 4,500 lbs
Top speed: 170 mph
Year built: 1930-31
ATC: 381
Comments: TWA and Army Y1C-19

The Northrop Alpha was an American single-engine, all-metal, seven-seat, low-wing monoplane fast mail/passenger transport aircraft used in the 1930s. Design work was done at the Avion Corporation, which in 1929, became the Northrop Aircraft Corporation based in Burbank, California.

Design & Development

Drawing on his experience with the Lockheed Vega, John K. Northrop designed an advanced mail/passenger transport aircraft. In addition to all-metal construction, the new Alpha benefited from two revolutionary aerodynamic advancements: wing fillets researched at the Guggenheim Aeronautical Laboratory at the California Institute of Technology, and a multicellular stressed-skin wing of Northrop's own design which was later successfully used on Douglas DC-2 and Douglas DC-3. In addition, the Alpha was the first commercial aircraft to use rubber deicer boots on wing and empennage leading edges which, in conjunction with state-of-the-art radio navigation equipment, gave it day or night, all-weather capability. The aircraft first flew in 1930, with a total of 17 built. The Alpha was further developed into a dedicated fast transport Northrop Gamma.

Operational History

The Alpha entered service with Transcontinental & Western Air (future TWA) making its inaugural flight on 20 April 1931. The trip from San Francisco to New York required 13 stops and took just over 23 hours. TWA operated 14 aircraft until 1935, flying routes with stops in San Francisco, California; Winslow, Arizona; Albuquerque, New Mexico; Amarillo, Texas; Wichita, Kansas; Kansas City, Missouri; St. Louis, Missouri; Terre Haute, Indiana; Indianapolis, Indiana; Columbus, Ohio; Pittsburgh, Pennsylvania; Philadelphia, Pennsylvania; and New York. Three Alphas were operated by the US military as C-19 VIP transports until 1939.

The third Alpha built, NC11Y, was re-acquired by TWA in 1975, and is preserved at the Smithsonian National Air and Space Museum.

Variants

Northrop Alpha 2: Seven-place (six-passenger) closed-cabin land monoplane.
Northrop Alpha 3: One/three-place (two-passenger plus cargo) closed-cabin land monoplane. Several Alpha 2s were converted to this configuration.
Northrop Alpha 4: One-place open-cockpit land monoplane cargo version with 2 ft (0.6 m) increased wingspan, all converted from Alpha 3s.
Northrop Alpha 4A: One-place open cockpit land monoplane cargo version, all converted from Alpha 4s.
Northrop YC-19 & Y1C-19: USAAC military VIP transport, seating reduced to 4 passengers, serial numbers 31-516 to 31-518, YC-19 had a Pratt & Whitney R-1340-7, while the Y1C-19s had the R-1340-11 engine.

Operators

United States
Trans World Airlines
US Army Air Corps

Specifications (Alpha 2)

Type:

Seven-place (six-passenger) closed-cabin all-metal land monoplane.

Wings:

Low-wing cantilever monoplane.
Outer sections are attached to short wing stubs, which are built integral with the fuselage.
Outer sections are of the multi-cellular stressed-skin type and are built entirely of "Alclad."

Fuselage:

Oval section structure, monocoque construction.
A smooth Alclad skin, with integrally-formed longitudinal stiffeners, carries the entire fuselage stresses.
The structure is strengthened with ring-shaped bulkheads built up with a channel cross-section.

Tail Unit:

Normal monoplane type.
It is of all-metal construction and entirely cantilever.
The structure is of the multi-cellular type, as used in the wings.

Undercarriage:

Divided type.
Consists of two Vees, incorporating oleo and rubber-in-compression springing, attached to the extremities of the wing stubs and two axles, the inner ends of which are hinged to the center-line of the underside of the fuselage.
Wheel-brakes and full swiveling tail-wheel.
Wheel undercarriage interchangeable with floats.

strong>Power Plant:

One 420 Hp Pratt & Whitney Wasp air-cooled radial engine, enclosed in an NACA cowling.
Fuel tanks (two) are carried in the wing stubs.

Accommodation:

Enclosed cabin for six passengers over the wing.
Open pilot cockpit located aft of the cabin and the rear baggage compartment.
Cubic capacity of the cabin is 120 ft³.
Standard equipment consists of a hand inertia-starter, navigation lights, rate of climb and turn and bank indicators, in addition to the usual instruments.
Special equipment such as generator, landing lights, flares and wireless can be installed if desired, at slight extra cost.

Dimensions:

Span: 41 ft 10 in (13 m)
Length: 28 ft 4½ in (8.65 m)
Height: 9 ft 0 in (2.7 m)
Wing area: 295 ft² (27.4 m²)

Weights and Loadings (Landplane):

Weight empty: 2,660 lbs (1,208 kg)
Weight loaded: 4,500 lbs (2,043 kg)
Wing loading: 15.25 lb/ft² (74.4 kg/m²)
Power loading: 10.7 lbs/hp (4.8 kg/hp)

Weights and Loadings (Seaplane):

Weight empty: 2,900 lbs (1,317 kg)
Weight loaded: 4,700 lbs (2,134 kg)
Wing loading: 15.9 lb/ft² (77.6 kg/m²)
Power loading: 11.2 lbs/hp (5.08 kg/hp)

Performance (Landplane):

Maximum speed: 170 mph (272 km/h)
Cruising speed: 145 mph (232 km/h)
Stalling speed: 60 mph (96 km/h)
Initial rate of climb: 1,400 ft/min (427 m/min)
Climb at 10,000 ft (3,050 m): 650 ft/min (198 m/min)
Climb to 10,000 ft (3,050 m): 10.5 min
Service ceiling: 19,300 ft (5,886 m)
Absolute ceiling: 21,100 ft (6,435 m)

Performance (Seaplane):

Maximum speed: 165 mph (264 km/h)
Cruising speed: 140 mph (224 km/h)
Initial rate of climb: 1,250 ft/min (381 m/min)
Climb at 10,000 ft (3,050 m): 550 ft/min (168 m/min)
Service ceiling: 18,000 ft (5,490 m)
Absolute ceiling: 20,000 ft (6,100 m)

References

Photos, Jim Hough, 2004
Historic photo, NASA Langley Research Center Photo Collection
Historic photo, Northrop Aircraft from the Skytamer Archive
Grey, C. G. and Bridgman, Leonard, Jane's All The World's Aircraft 1931, Sampson Low, Marston & Company, Ltd., London, 1931, pp. 303c-304c
Allen, Richard Sanders, The Northrop Story 1929-1939, Orion Books, New York, 1990, ISBN 0-517-56677-X, pp. 154-155
Aeronautical Chamber of Commerce of America, Inc., The Aircraft Year Book For 1931, D. Van Nostrand Company, Inc., New York, 1931, pp. 337
Wikipedia, Northrop Alpha, 8/2/2010.