The Northrop Delta was an

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

single-engined passenger transport aircraft of the 1930s. Closely related to Northrop's

Gamma Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...

mail plane A mail plane is an aircraft used for carrying mail. Aircraft that were purely mail planes existed almost exclusively prior to World War II. Because early aircraft were too underpowered to carry cargoes, and too costly to run any "economy class" ...

, 13 were produced by the Northrop Corporation, followed by 19 aircraft built under license by Canadian Vickers Limited.

Development and design

When

Jack Northrop John Knudsen Northrop (November 10, 1895 – February 18, 1981) was an American aircraft industrialist and designer who founded the Northrop Corporation in 1939. His career began in 1916 as a draftsman for Loughead Aircraft Manufacturing Com ...

set up the Northrop Corporation as a joint venture with the

Douglas Aircraft Company The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas; it then operated as ...

in 1932, he set out to design two closely related single-engined aircraft as the new company's first products: a mailplane/record-breaking aircraft, which was designated the

, and a passenger transport, the Delta.Francillon 1979, pp.23–24, 143. The Delta was a low-winged

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

, with a fixed

tailwheel undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynami ...

. It was of all-metal, stressed-skin construction, with streamlining spats covering the main landing gear. While the Delta's wings were common with those of the Gamma, it had a new, wider fuselage, which seated the pilot in an enclosed cockpit immediately behind the engine, and had accommodation for eight passengers in a cabin behind the pilot.Green 1967, p.57.Francillon 1979, p.157. The first Delta was flown in May 1933, and received an airworthiness certificate in August that year.

Operational history

Although it was intended that the Delta would be sold in both airliner and executive transport (initially named "Victoria") versions,''Flight'' 8 February 1934, p.123
a change to the regulations governing commercial air transport in the United States in October 1934, prohibiting the use of single-engined aircraft to carry passengers at night or over rough terrain which would prevent a forced landing, stopped the market for single-engined airliners in the United States, and only three aircraft, all ordered before the passing of this regulation, were built as airliners. These consisted of the prototype, leased to

Trans World Airlines Trans World Airlines (TWA) was a major American airline which operated from 1930 until 2001. It was formed as Transcontinental & Western Air to operate a route from New York City to Los Angeles via St. Louis, Kansas City, and other stops, with F ...

for use to carry

airmail Airmail (or air mail) is a mail transport service branded and sold on the basis of at least one leg of its journey being by air. Airmail items typically arrive more quickly than surface mail, and usually cost more to send. Airmail may be the ...

, which crashed on 10 November 1933, one sold to

Pan-Am Pan American World Airways, originally founded as Pan American Airways and commonly known as Pan Am, was an American airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States ...

for use by its Mexican subsidiary, destroyed by a fire in May 1934 and one sold to

AB Aerotransport AB Aerotransport (ABA) was a Swedish government-owned airline which operated during the first half of the 20th century and was merged into what would become the SAS Group. ABA was established on 27 March 1924 under the name Aktiebolaget Aerotr ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

, delivered in April 1934. AB Aerotransport purchased a second Delta, but this was a dedicated mailplane which more closely resembled the Gamma, with a slim fuselage carrying its cargo in a compartment ahead of the cockpit. A single aircraft was built for the

United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and law enforcement service branch of the United States Armed Forces and one of the country's eight uniformed services. The service is a maritime, military, mult ...

. Designated the Northrop RT-1, this was used as the personal transport of Henry Morgenthau, Jr., the

Secretary of the Treasury The United States secretary of the treasury is the head of the United States Department of the Treasury, and is the chief financial officer of the federal government of the United States. The secretary of the treasury serves as the principal a ...

and as a staff transport.Francillon 1979, p.163. Seven more aircraft were built as executive transports for private owners. Of these, three were purchased by the

Spanish Republicans Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Cana ...

for use in the

Spanish Civil War The Spanish Civil War ( es, Guerra Civil Española)) or The Revolution ( es, La Revolución, link=no) among Nationalists, the Fourth Carlist War ( es, Cuarta Guerra Carlista, link=no) among Carlists, and The Rebellion ( es, La Rebelión, lin ...

. Two of these aircraft were captured by the Nationalists when the ship carrying them (along with four

Vultee V-1 The Vultee V-1 was a 1930s American single-engined airliner built by the Airplane Development Corporation, designed by Gerard Vultee and financed by automobile manufacturer Errett Cord. Design and development The prototype (designated the ...

s, a

Fairchild 91 The Fairchild 91, (a.k.a. A-942), was a single-engine eight-passenger flying boat airliner developed in the United States in the mid-1930s.Taylor, Michael J.H. . ''Jane's Encyclopedia of Aviation”. Studio Editions. London. 1989. Design Fairch ...

and a Lockheed Electra) was captured at sea. These two Deltas were used as Transports by Franco's forces, while the third Delta was used by the Republican airline

Lineas Aéreas Postales Españolas LAPE, Spanish Postal Airlines ''(Líneas Aéreas Postales Españolas)'', was Spain's national airline during the Second Spanish Republic. History LAPE, often also spelt L.A.P.E. and colloquially known as ''"Las LAPE"'', replaced CLASSA (''Comp ...

(LAPE) until the end of the civil war when it was handed over to Franco's air force.Francillon 1979, pp.159–161. In 1935, Canada selected the Delta for use as a photographic survey aircraft for use by the

Royal Canadian Air Force The Royal Canadian Air Force (RCAF; french: Aviation royale canadienne, ARC) is the air and space force of Canada. Its role is to "provide the Canadian Forces with relevant, responsive and effective airpower". The RCAF is one of three environm ...

(RCAF), to be built by

Canadian Vickers Canadian Vickers Limited was an aircraft and shipbuilding company that operated in Canada during the early part of the 20th century until 1944. A subsidiary of Vickers Limited, it built its own aircraft designs as well as others under licence. C ...

under license. One aircraft, the last Delta built by Northrop, was supplied as a part assembled pattern to Canadian Vickers, first flying on 16 August 1936 and being delivered to the RCAF on 1 September that year.Green 1967, p.58. It was followed by a further 19 aircraft built wholly by Canadian Vickers, production continuing until October 1940.Green 1967, p.60. The Northrop Delta was the first completely all-metal, stressed-skin aircraft built in Canada, however it was closely preceded by the

Fairchild Super 71 The Fairchild Super 71 was a Canadian parasol-mounted high-wing monoplane cargo aircraft built by Fairchild Aircraft Ltd. (Canada). The Super 71 was an entirely new design that was one of the first purpose-built civilian bush planes for use in re ...

, whose stressed skin construction was limited to the fuselage and not the flying surfaces. The Deltas, which were capable of being operated from wheeled, ski or float undercarriages, proved capable survey aircraft, well suited to operations in the North of Canada, but in August 1939, when the outbreak of the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

loomed, Canada found itself short of coastal patrol aircraft, and the Deltas were diverted to this role, being fitted with floats and carrying out long anti-submarine missions. The Deltas were less successful as patrol floatplanes, as they were damaged by ocean swell and by salt water corrosion, and they were forced to revert to landplane use after two months. The Delta was withdrawn from operations in late 1941, then being used as instructional airframes in training schools.Green 1967, p.60.

Variants

Aerovias Centrales Northrop Delta 1B X-ABED

Richfield Oil Company - The Richfield Eagle - Northrop Delta 1D NC13777 (cropped)

RCAF Canadian Vickers-built Northrop Delta Mk

;Delta 1A :Prototype. Powered by Wright SR-1820-F3 Cyclone radial engine. One built. ;Delta 1B :Passenger airliner for Pan-Am. Powered by

Pratt & Whitney Hornet The Pratt & Whitney R-1690 Hornet was a widely used American aircraft engine. Developed by Pratt & Whitney, 2,944 were produced from 1926 through 1942. It first flew in 1927. It was a single-row, 9-cylinder air-cooled radial design. Displacemen ...

. One built.Francillon 1979, p.158. ;Delta 1C :Passenger airliner for AN Aerotransport. Powered by Hornet. ;Delta 1D :Executive aircraft, powered by Cyclone or Hornet engines. Eight built, including one Northrop RT-1, powered by Cyclone for United States Coast Guard. ;Delta 1E :Airmail carrier for AB Aerotransport. One built. Powered by Hornet.Francillon 1979, p.159. ;Delta I :Survey aircraft for RCAF. Powered by SR-1820-F52 Cyclone. Three built, including pattern aircraft and two license built. Based on the 1D-8. ;Delta IA :Partial modification to Mk.II standards, with bomb racks fitted. ;Delta II :Revised version with provision for armament, including bombs, a dorsal turret mounting a .30 in

Browning machine gun Browning machine guns are a family of machine gun designs by John Browning, a prolific weapon designer. These include: *M1895 Colt–Browning machine gun, based on a design dating to 1889, was the first successful gas-operated machine gun to ent ...

(later removed) and two wing mounted machine guns. Nine built.Green 1967, p.593 ;Delta III :Unofficial designation for Mk.II fitted with enlarged tail surfaces to counter tail buffeting from turret. Eight built. ;RT-1 :United States Coast Guard designation for its sole Delta 1D-7, which was named "Golden Goose".

Military operators

; *

Royal Australian Air Force "Through Adversity to the Stars" , colours = , colours_label = , march = , mascot = , anniversaries = RAAF Anniversary Commemoration ...

– Operated one impressed Delta from December 1942 to September 1943. ; *

No. 8 Squadron RCAF No. 8 Squadron RCAF was a unit of the Royal Canadian Air Force (RCAF) that was in operation from 1936 to 1945. History No. 8 Squadron was formed on the 14 February 1936 as a General Purpose (GP) squadron at Winnipeg, Manitoba. The squadron moved ...

** No. 119 Squadron RCAF ** No. 120 Squadron RCAF ; *

Spanish Republican Air Force The Spanish Republican Air Force was the air arm of the Armed Forces of the Second Spanish Republic, the legally established government of Spain between 1931 and 1939. Initially divided into two branches: Military Aeronautics ('' Aeronáutica M ...

– ex-Swedish Northrop 1C Delta with

LAPE LAPE, Spanish Postal Airlines ''(Líneas Aéreas Postales Españolas)'', was Spain's national airline during the Second Spanish Republic. History LAPE, often also spelt L.A.P.E. and colloquially known as ''"Las LAPE"'', replaced CLASSA (''Compa ...

*Nationalist Air Force - Northrop 1D Delta captured on Mar Cantabrico ; *

Civil operators

; * Civil Aviation Authority of Australia ; * Aerovias Centrales SA (a

Subsidiary) ; *

(now part of SAS) ; *

(aka TWA) *

Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...

(executive aircraft) * Richfield (executive aircraft)

Specifications (Delta 1D-5)

References

;Notes ;Bibliography *
The Latest Northrops: The "Victoria" and "Delta" Models
. ''

Flight Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...

'', 8 February 1934. pp. 123–124. * Francillon, René J. ''McDonnell Douglas Aircraft since 1920''. London:Putnam, 1979. . * Green, William. ''War Planes of The Second World War:Volume Seven – Bombers and Reconnaissance Aircraft''. London:Macdonald, 1967.

External links

Canadianwings.com
{{ADF aircraft designations 1930s United States civil utility aircraft

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

1930s United States airliners Low-wing aircraft Single-engined tractor aircraft Aircraft first flown in 1933