The Northrop Alpha represents a notable point of transition in modern airline design, for it combined features of the past and of the future in a very utilitarian package. The passengers were enclosed in a comfortable cabin, while the pilot remained exposed—and sensitive—to the elements. The modern aspects of the Alpha—an all-metal structure, semimonocoque fuselage, and cantilever wing—were partially offset by the use of a single engine and fixed gear.

John K. Northrop, who had previously designed the Lockheed Vega, conceived of the Alpha as a means of proving his ideas for quantity production of an all-metal airplane with the machine tools existing in the early 1930s. Always pioneering new ideas and new techniques, Northrop became one of the most influential men in the aviation industry.

The Alpha was designed to be a high-performance plane that could carry mail and passengers out of small fields. The plane was attractive to airlines because of its comparatively high top speed (177 mph for later models) and high reliability. The latter was due in large part to the use of the dependable air-cooled Pratt and Whitney Wasp engine of 420 horsepower.

With the advent of the larger twin-engine Boeing and Douglas transports, the Northrop Alphas were relegated to carrying freight, serving well in this capacity. The Alpha could fly from coast to coast in twenty-three hours, carrying such commodities as freshly cut gardenias, silk worms, medical serums, and auto parts. Stops were made at Winslow (Arizona), Albuquerque, Amarillo, Wichita, Kansas City, St. Louis, Terre Haute, Indianapolis, Columbus, Pittsburgh, Philadelphia, and New York.

Although the Alpha served well, its real importance was its demonstration of Northrop’s multicellular wing and stress skin construction. These concepts were of fundamental importance to the Douglas DC-2 and DC-3.

Transcontinental & Western Air (which was to become TWA) was the launch customer and ordered 5 alphas. Those aircraft began services on April 20, 2020 from San Francisco to New York with 13 intermediate stops. The entire trip took just over 23 hours.

Alpha - Model 2

Capacity: Pilot + 6 passengers
Powerplant: P&W R-1340 Wasp (420 hp)
Length: 28 ft 4-1/2 in Height: 9 ft Wingspan: 41 ft 10 in Wing Area: 295 sq ft Airfoil: Clark Y (18% at Root, 12% at tip)
Gross Weight: 4,500 lb Empty Weight: 2,590 lb Useful Load: 1,910 lb Payload with full fuel and 170 lb pilot: 940 lb Wing Loading: 14.4 lb/sq ft Power Loading: 10.7 lb/hp
Top Speed: 170 mph Cruising Speed: 145 mph Landing Speed: 60 mph Climb at Sea Level : 1400 fpm Climb at 10,000 ft : 650 fpm Time, SL to 10,000 ft: 10.5 min Service Ceiling: 19,300 ft Absolute Ceiling: 21,100 ft Takeoff Ground Roll: 535 ft Landing Ground Roll: 475 ft Fuel: 116 gal Oil: 13 gal Years Manufactured: 1930-31 Quantity Manufactured: 12 Certification: ATC 381

Alpha - Model 3

Capacity: Pilot + 2 passengers + Cargo or Pilot + Cargo
Powerplant: P & W R-1340 Wasp C (420 hp)
Length: 28 ft 4-1/2 in Height: 9 ft Wingspan: 41 ft 10 in Wing Area: 295 sq ft Airfoil: Clark Y (18% at Root, 12% at tip)
Gross Weight: 4,500 lb Empty Weight: 2,679 lb Useful Load: 1,821 lb
Top Speed: 170 mph Cruising Speed: 145 mph Landing Speed: 60 mph Climb at Sea Level : 1400 fpm Climb at 10,000 ft : 650 fpm Climb SL to 10,000 ft: 10.5 min Service Ceiling: 19,300 ft Absolute Ceiling: 21,100 ft Takeoff Ground Roll: 535 ft Landing Ground Roll: 475 ft
Fuel: 116 gal Oil: 13 gal Years Manufactured: 1931 Certification: Group 2-335
Quantity Manufactured: 5 as original equipment. A number of Model 2's were converted to Model 3's by the factory.

Alpha - Model 4

Capacity: Pilot + Cargo
Powerplant: P&W R-1340 Wasp C (420 hp)
Length: 28 ft 4-1/2 in Height: 9 ft Wingspan: 43 ft 10 in Wing Area: 312 sq ft
Gross Weight: 4,700 lb Empty Weight: 2,800 lb Useful Load: 1,900 lb
Top Speed: 177 mph Certification: ATC 451
Quantity Manufactured: None as original equipment. Most Model 3's were converted to the Model 4 configuration.

Alpha - Model 4a

Capacity: Pilot + Cargo
Powerplant: P&W R-1340 Wasp C (420 hp)

Length: 28 ft 4-1/2 in Height: 9 ft Wingspan: 43 ft 10 in Wing Area: 312 sq ft
Gross Weight: 5,100 lb Empty Weight: 2,650 lb (2,660 for NC11Y as equipped) Useful Load: 2,450 lb
Top Speed: 177 mph Certification: ATC 461
Quantity Manufactured: None as original equipment. Most Model 4's were converted to the Model 4a configuration.