While Northrop was working on the YA-13/XA-16 developments of the Gamma, the company was also testing a scaled-down version for the US Navy under the designation Northrop XFT-1. This was one of two Northrop prototypes which failed to attract production orders, the other being the Type 3-A of 1935. Both were all-metal fighters, the XFT-1 with fixed landing gear being intended for the US Navy. Powered originally by a 466kW Wright XR-1510 radial, it was later re-engined, as the XFT-2, with a 485kW Pratt & Whitney R-1535, but crashed three months later, in July 1936.

The Northrop 3-A was a similar design for the US Army, but differed from the navy aircraft in having retractable landing gear and a modified canopy. Developed alongside these prototypes was the XBT-1, which had semi-retractable landing gear, and this entered production as the BT-1 torpedo-bomber, the first of 54 being delivered in April 1938. The BT-1 had a 615kW Pratt & Whitney R-1535 Twin Wasp Junior radial engine, but one aircraft was modified as the BT-2 to have revised landing gear and a 597kW Wright XR-1820 Cyclone. With other modifications this was to become the Douglas SBD Dauntless as the original Northrop Corporation had by then become the El Segundo Division of Douglas.

Based on the design of the XFT, the Model 3A was developed as a contender in the US Army’s Materiel Division competition for a successor to the P-26 in service with the USAAC. A low-wing all-metal semi-monocoque monoplane with fully-retractable main undercarriage members and an enclosed cockpit, the Model 3A was powered by a Pratt & Whitney SR-1535-6 Twin Wasp Junior 14-cylinder radial engine rated at 700hp for take-off. It had provision for one 7.62mm and one 12.7mm gun in the fuselage. Completed in July 1935, it was briefly tested at Wright Field where it was found to be somewhat unstable and prone to spinning. Returned to the manufacturer for modification, the Model 3A was under test over the Pacific on 30 July, but failed to return, no trace of the aircraft nor its pilot ever being found. The design of the Model 3A was subsequently sold to Chance Vought Aircraft which further developed it as the V-141.

3A
Max take-off weight: 1769 kg / 3900 lb
Wingspan: 10.21 m / 33 ft 6 in
Length: 6.78 m / 22 ft 3 in
Height: 2.77 m / 9 ft 1 in
Wing area: 17.37 sq.m / 186.97 sq ft
Max. speed: 434 km/h / 270 mph

Despite some scepticism concerning the practicability of the monoplane configuration for the shipboard fighter, the US Navy’s BuAer issued a second requirement for such a warplane on 24 January 1933, the first having been issued seven weeks earlier and for which the Boeing Model 273 was designed and built (as the XF7B-1). To meet the later but essentially similar requirement, a contract was let to Northrop for a prototype assigned the designation XFT-1.

A single-seat all-metal cantilever monoplane with split flaps, spatted main undercarriage members and an enclosed cockpit, the XFT-1 was designed by a team led by Ed Heinemann. Powered by a Wright R-1510-26 14-cylinder radial rated at 600hp at sea level and 625hp at 1830m, and carrying two 7.62mm cowl guns, the XFT-1 first flew on 16 January 1934.

The US Navy was critical of its manoeuvrability, its tendency to spin out of certain manoeuvres, its low speed characteristics and its landing speed. During the course of initial tests, an XR-1510-8 engine affording 650hp at 2590m was substituted for the -26, and, in April 1936, the XFT-1 was returned to the manufacturer for more extensive modification. A Pratt & Whitney R-1535-72 Twin Wasp Jnr 14-cylinder radial rated at 700hp for take-off and 650hp at 2285m was installed, this having a long-chord cowling; the vertical tail surfaces were enlarged, and the mainwheel spats were revised.

Redesignated XFT-2, the fighter was now 118kg heavier in empty condition, speed and climb performance were marginally improved, but manoeuvrability and low speed characteristics were worse. It was pronounced unairworthy by the US Navy and crashed on 21 July 1936 while being returned to its manufacturer.

XFT-1
Max take-off weight: 1704 kg / 3757 lb
Empty weight: 1120 kg / 2469 lb
Wingspan: 9.75 m / 31 ft 12 in
Length: 6.43 m / 21 ft 1 in
Height: 2.87 m / 9 ft 5 in
Wing area: 16.44 sq.m / 176.96 sq ft
Max. speed: 378 km/h / 235 mph
Range: 1570 km / 976 miles

While the Gamma was being developed, Northrop was working on a nine-seat transport, which was basically a new fuselage married to Gamma wings. Unfortunately for Northrop, the US 1926 Air Commerce Act was amended to prohibit the use of single-engine aircraft for carrying passengers by night, or over rough terrain where emergency landings could not be made. Consequently, airline use for its intended role was nonexistent in the USA, although three had been sold before the new regulation was announced. Eight others were used as executive transports, and one was bought by Swedish AB Aerotransport, which subsequently acquired a second.

The US Coast Guard operated a Delta under the designation RT-1, as the Secretary of the Treasury’s personal aircraft.

The last Delta was supplied to Canada as a pattern aircraft for assembly in that country by Canadian Vickers, who built 20 of various marks with both wheel and float landing gear. Deltas were flown with various engines, including the 529kW and 548kW Wright SR-1820, 485kW, 492kW and 522kW Pratt & Whitney Hornets.

In January 1932 John Northrop and Donald Douglas formed the Northrop Corporation and the first aircraft from the new corporation was the Northrop Gamma, several of which were built to special order for record-breaking flights and research work. The first two aircraft, a Gamma 2A and a Gamma 2B, were powered respectively by a 585kW Wright and 373kW Pratt & Whitney Wasp radial. Both were delivered at the end of 1932, the first to Texaco who loaned it to Frank Hawks for record-breaking flights.

Gamma NR12265 was built for Lieutenant Commander Frank Hawks of the Texas Company, as a long-range, high speed mail transport in 14/2/33. Named Texaco Sky Chief, it was flown out to the Antarctic via South America to assist with the search for Lincoln Ellsworth when he and pilot Herbert Hollick-Kenyon were declared missing in late 1935. Later sold to “Gar’ Wood and renamed Kinjockety II, it exploded in midair during the 1936 Bendix Trans¬continental Race.

The second, 2B NR12269, being the first to fly after being completed in August 1932. Sold in early 1933 to millionair explorer Lincoln Ellsworth, it was shipped to the Antarctic in late 1933 and test flown on skis by Bernt Balchen before being damaged in an unseasonable ice breakup. The aircraft was back in Dunedin, New Zealand, on 28/1/34 for transshipment on to California for repairs. Returned to the United States after the successful trans polar cap flights between 23/11 and 9/12/35, the Gamma was presented to the Smithsonian on 25/4/36.

TWA bought three Gamma 2D aircraft with 529kW Wright Cyclone engines as single-seat mailplanes in 1934. The second was later re-engined with a 578kW Wright and was used by Texaco to test oil temperatures and flows before being sold to the US Army Air Corps, which designated it UC-100.

A number of Gammas were delivered to individual customers, including two to the UK, a 2E for the Aeroplane & Armament Experimental Establishment and a Gamma 2L, the last to be built, was used by the Bristol Aeroplane Co. as a test-bed for its Hercules engines.

The Chinese government ordered 24 Gamma 2E aircraft as light bombers, with 529kW Wright engines. They could carry a 726kg bombload and had four 7.62mm forward-firing machine-guns in the wings, and one rearward-firing in the rear cockpit. A further 25 Gamma 2Es were assembled in China from components provided by Northrop.

Engine: Pratt & Whitney Wasp, 500 hp
Seats: 2
Range: 2000 miles

In 1931 Northrop built the prototype of an all-metal low-wing sporting monoplane X/NC12214, the Beta (ATC 2-401), a two-seater with a 119kW Menasco Buccaneer inline engine.

Designed by Don Berlin, a dorsal fairing and canopied cockpit were later added. An advertisement in Dec 1932 Aero Digest quoted a $5,000 sale price.

It was converted to single-seat high-speed mailplane configuration in 1933 and fitted with a 300 hp / 224kW Wright Whirlwind radial engine, in which form it became the first aircraft of such power to exceed 200mph / 322km/h. Reported speeds up to 212 mph were reached.

Damaged in a landing accident on 16 January 1933, it was rebuilt by Stearman for planned testing of various wing flaps, but destroyed in a crash on 5 June 1934.

Beta 3D
Engine: 300hp P&W Wasp Jr
Wing span: 32’0
Seats: 1

Northrop’s first aircraft for his new company was known as the Flying Wing but of more immediate consequence was the next design, the Northrop Alpha, an all-metal seven-seat single-engine low-wing monoplane. In 1929 Avion Corporation became the Northrop Aircraft Corporation, a division of United Aircraft and Transport Corporation of which Boeing was also a part.

Northrop Alpha Article

First flown in 1930, Trans Continental and Western Air Inc, (later to become Trans World Airlines) ordered five Alphas with 313kW Pratt & Whitney Wasp engines and began services on 20 April 1931 from San Francisco to New York, with 13 intermediate stops, the journey taking just over 23 hours.

The Alphas were configured for three passengers and 211kg of mail and cargo, for mail flying was a plum contract at that time, but regularity and reliability was required. To achieve all-weather and night-flying capability, the Alphas had the most modern radio and navigation equipment, and for winter operations became the first commercial type to be fitted with Goodrich rubber de-icer boots on wing “and tail surface leading edges.

Thirteen of the 17 Alphas built saw service with TWA, and three were supplied for evaluation to the US Army Air Corps where, had production orders been given, they would have been designated C-19.

Various configurations carried the designations Alpha 2, Alpha 3, Alpha 4 and Alpha 4-A, and a number of changes were made between individual aircraft as late modifications were made retrospectively to earlier aircraft, including fitting of streamlined ‘trousers’ over the original rather utilitarian landing gear.

The 1931 Alpha 3 was certified under ATC 2-335. The 1931 Alpha 4 (ATC 451) prototype was built at Northrop, the rest at Wichita. Eleven were built, of which 7 were modified from Northrop Alpha 2 and 3. ATC 2-371 was for Alpha 4 NC127W powered by a 420hp Wasp installation.

The 1932 Alpha 4A (ATC 461) was a single-place cargo conversions of Alpha 4. Ten were built.

The last conversion was the Gamma 4-A, an all-cargo aircraft which could carry 567kg; the Gamma 4 and Gamma 4-A had a 336kW Wasp engine and most of the earlier aircraft were similarly retrofitted.

The last surviving Alpha, the third built, served with the US Assistant Secretary of Commerce for Aeronautics, the Ford Motor Company, National Air Transport (part of United Airlines) and TWA. It was re-acquired by the airline in 1975 and superbly restored before being placed in Washington’s Smithsonian Institution National Air and Space Museum.

Alpha 3
Engine: 420hp P&W Wasp
Seats: 3

Alpha 4
Engine: 450hp P&W Wasp
Wingspan:
43’10”
Length: 28’5″
Useful load: 1900 lb
Max speed: 177 mph
Cruise: 155 mph
Stall: 62 mph
Range: 650 mi

Alpha 4
Engine: 420hp P&W Wasp

Alpha 4A
Seats: 1
Useful load: 2450 lb
Max speed: 177 mph
Cruise: 155 mph
Stall: 62 mph
Range: 900 mi

Jack Northrop in 1928 wanted to “do his own thing”, which was to start investigating all wing aircraft, He decided to keep a tail, for the time being. So the Northrop Flying Wing, with experimental registration X 216H, was intended to solve only some of the problems. The wing was a fairly conventional shape, apart from the thick centre section so that the pilot and passenger could sit comfortably inside it on each side of the centre line. The whole structure was a duralumin cellule with multiple spars and a stressed skin. To the rear projected an extremely, light pair of duralumin monocoque tail booms carrying a twin finned tail, the whole assembly weighing less than half as much as a conventional rear fuselage and tail. The main wheels were well forward under the leading edge, and under the trailing edge was a large steerable tailwheel.

The 90 hp / 67kW Menasco Pirate engine was carried just ahead of the leading edge, with cooling air ducted to an outlet near the trailing edge. Northrop was deeply concerned to secure smooth airflow over his flying wings and never again put a propeller in front of one.

The aircraft, built by Northrop’s newly formed Avion Corporation (later the Northrop Aircraft Corporation), initially driving a pusher propeller but modified later to tractor configuration.

X 216H flew perfectly well. Reports say it flew well and was 25% faster than anything else in its class. It had conventional controls, and Northrop wanted to explore alternative arrangements and ultimately take the giant step of removing the tail, but he was prevented by financial and business difficulties.