Junkers F 13

Junkers
Company type	Private
Industry	Aerospace
Founded	February 5, 1895; 131 years ago in Dessau, Germany
Founder	Hugo Junkers
Headquarters	Dessau, Germany
Products	Aircraft, including Junkers F 13

The Junkers F 13 holds the distinction of being the first all-metal transport aircraft globally, developed and manufactured by the German company Junkers shortly after the end of World War I. It showcased a cantilever-wing monoplane configuration with an enclosed cabin accommodating four passengers and an open cockpit designed for two crew members. Consistent with other Junkers designs produced between 1918 and 1932, it featured a duralumin alloy framework sheathed in corrugated, load-bearing duralumin skin. The wing assembly incorporated nine circular duralumin spars reinforced by transverse bracing, while all control surfaces were equipped with horn balances.

With a production total of 322 units—a remarkable quantity for that era—the F 13 operated worldwide and represented more than one-third of the air traffic during the early 1920s. Its manufacturing period lasted thirteen years, and its commercial use extended beyond thirty years. The model was available in various configurations, including floatplane versions, ski-equipped variants, mail carriers, and diverse engine options. Several examples are preserved in museums today, and a faithful reproduction was constructed in the 2010s, bringing the type back into the spotlight nearly a hundred years after its inaugural flight.

Development

The F 13's origins trace back to Professor Hugo Junkers’ experimental work in Dessau throughout the 1910s, where he advanced lightweight metal construction techniques alongside aerodynamic innovations.

This aircraft was designed as a streamlined, all-metal low-wing cantilever monoplane—marking Junkers' initial venture into commercial aviation and standing as the world’s first passenger plane constructed entirely from metal. The letter "F" in its designation stood for Flugzeug (the German word for aircraft), replacing earlier "J" series labels; versions produced in Russia bore the designation Ju 13.

Its first flight took place on 25 June 1919, powered by a 127 kW (170 hp) Mercedes D.IIIa inline water-cooled engine. Subsequent early production models were equipped with larger wings and upgraded to a more powerful 140 kW (185 hp) BMW IIIa powerplant.

Multiple variants incorporated engines from manufacturers such as Mercedes, BMW, Junkers, Armstrong Siddeley Puma inline engines, as well as Gnome-Rhône Jupiter and Pratt & Whitney Hornet radial engines. These variants were identified by two-letter suffixes indicating their airframe and engine combinations; for instance, "-fe" referred to the long-fuselage "-f" airframe fitted with an L5 engine.

The F13 served as the developmental basis for later models like the Junkers W 33 and Junkers W 34.

Design

The Junkers F 13 stood out as an all-metal transport aircraft featuring a pioneering design element: a cantilever wing that lacked external struts or bracing wires, thereby minimizing aerodynamic drag. Its internal wing support necessitated a thicker wing profile, which contributed to efficient aerodynamic performance over diverse flight regimes.

Departing from traditional wood-and-fabric construction methods, the F 13 utilized duralumin—a lightweight metal alloy innovated by Junkers himself. This material choice enhanced structural integrity, simplified engineering calculations, improved maintainability, lowered fire hazards, and eliminated problems related to wood such as warping or termite damage. Although duralumin had a higher specific gravity than wood, careful aerodynamic refinement resulted in an aircraft lighter than comparable wooden designs. Its metal structure also provided increased durability, making it especially suitable for operations in tropical climates like those found in South America.

The wing was divided into three sections to facilitate transportation; outer panels attached to a central wing framework consisting of nine duralumin tubes ensured symmetrical assembly that could be completed swiftly by just two workers. Corrugated metal skin enhanced torsional rigidity and resistance to dynamic stresses. The fuselage was mounted atop the wing’s center section, forming a robust yet lightweight superstructure that improved occupant safety during rough landings.

Control systems followed conventional layouts: elevators and ailerons were manipulated via a control column equipped with a wheel while the rudder was controlled by foot pedals. Sliding doors allowed easy inspection of control cables, and dual control setups could be installed for extended flights. Large tail surfaces contributed to improved handling and stability. A distinctive pilot-operated trimming tank adjusted fuel distribution to maintain balance under varying load conditions.

The landing gear comprised steel tubing reinforced with four streamlined spring struts arranged in a V-shaped configuration to ensure rigidity. A wide wheelbase reduced tipping hazards during uneven landings. The tail skid featured a jointed shock absorber protecting the fuselage and was designed for quick replacement. Conversion to floatplane configuration using duralumin floats or fitting skis for snow or ice operations could be accomplished rapidly.

Thanks to its aerodynamic refinement, the F 13 accommodated engines from several manufacturers with ease of maintenance due to accessible components. A Junkers-designed frontal radiator optimized cooling efficiency while maintaining low weight; pilots could adjust it during flight, and tropical variants included an additional radiator unit. Propeller development emphasized pitch optimization along with blade shape and diameter adjustments. Early laminated wooden propellers incorporated metal leading edges for durability; later metal propellers featured interchangeable blades and adjustable pitch hubs to optimize either cruising speed or climb performance.

The semi-enclosed cockpit offered overhead protection but lacked side windows for the crew. Passengers enjoyed an enclosed, heated cabin furnished with windows, doors, and seat belts—features that were uncommon at that time—accommodating four passengers plus an additional seat adjacent to the pilot. The F 13 employed fixed conventional split landing gear with a rear skid; some variants could be outfitted with floats or skis as required. Its cabin was spacious and elegantly appointed compared to contemporaneous aircraft designs.

Operational history

Following World War I, manufacturers of civilian aircraft encountered competition from surplus military planes, such as the DH.9C, which were adapted for non-military purposes. German companies faced additional challenges due to production bans imposed by the Inter-Allied Aeronautical Commission during 1921–22. Despite these obstacles, Junkers secured early international contracts in 1919, supplying aircraft to Austria, Poland, the United States, SCADTA (Colombia), and the United States Post Office Department. In the United States, John Larsen Aircraft obtained a license to produce the model as the JL-6. By 1922, sales had expanded to countries including England, France, Italy, and Japan.

The F13 became a dominant force in early commercial aviation, reportedly accounting for approximately 40% of worldwide air traffic in the early 1920s.

In Bolivia, LAB initiated its operations in 1925 using a Junkers F 13 based out of Cochabamba.

To boost domestic adoption of the F 13, Junkers established its own airline, Junkers Luftverkehr AG, in 1921. By 1923, this airline operated a fleet of 60 F 13s and expanded internationally with a branch office in Iran. Innovative marketing strategies such as low-cost leasing and interest-free loans helped secure around 16 European operators flying this model. After merging into Luft Hansa in 1926, the combined fleet had accumulated 9.5 million miles flown. Luft Hansa acquired 55 aircraft and deployed them across 43 domestic routes by 1928; even as late as 1937, more than 50 weekly flights continued on four routes until their retirement in 1938.

Most of the F 13 units were produced at Junkers’ Dessau facility; however, during the restrictive period between 1921 and 1923, manufacturing shifted to factories located in Danzig and Reval. A major contract with the Soviet Union led to licensed production at "Plant no. 22" situated in Fili near Moscow. These aircraft were utilized by Soviet airlines as well as the Red Army.

Among military users, the Colombian Air Force employed F 13s and related variants as bombers during the Colombia–Peru War (1932–33). The Republic of China operated modified scout bombers until their destruction during the January 28 Incident (1932) by Japanese forces. The Turkish Flying Forces also incorporated several units into their fleet.

A notable international feature of the F 13 was its easily interchangeable landing gear that could be swapped for pontoons, facilitating seaplane operations—an essential capability in regions where water bodies were more prevalent than airstrips. Apart from fitting floats, only minor adjustments were necessary; occasionally extended rudders were added to enhance directional control.

First introduced in 1919, F 13 aircraft remained in commercial service for over thirty years, with the final units retiring in Brazil by 1951.

Back in production 2009-2019

A German-Swiss initiative to recreate the F 13 began in 2009, culminating with its inaugural flight in September 2016. This reproduction incorporates modern radio and transponder systems while employing a period-authentic 1930s Pratt & Whitney R-985 Wasp Junior engine, maintaining fidelity to the original design. Additional replicas are available for purchase at $2.5 million each.

Junkers Flugzeugwerke (SD303) revived production of the F 13 as a tribute to Hugo Junkers’ heritage. Completed in 2016, this aircraft was presented at EBACE to commemorate the type’s centenary and is offered for sale with three further units under construction. By 2019, assembly of the second and third airframes was underway; the second was scheduled for its first flight by early summer.

The replica’s maiden flight on September 15, 2016 marked a significant milestone following extensive development efforts. Built using original blueprints alongside laser scans from the Museum of Air and Space’s model at Le Bourget, Paris, it consists of approximately 2,600 components and tens of thousands of rivets and is powered by a Wasp radial engine.

Variants

F 13: initial prototype featuring reduced wing dimensions (wingspan 14.47 m/47 ft 5.75 in, wing area 38.9 m²/419 ft²) and powered by a less potent 127 kW (170 hp) Mercedes D IIIa inline engine.
F 13a: the first series production model equipped with a 140 kW (185 hp) BMW IIIa engine.
F 13ba, ca, da, fa: variants fitted with a 149 kW (200 hp) Junkers L2 upright inline water-cooled powerplant along with structural enhancements; the fa model was approximately one meter longer.
F 13be, ce, de, fe: similar to the above but upgraded with a 230 kW (310 hp) Junkers L5 upright inline water-cooled engine.
F 13dle, fle, ge, he, ke: versions powered by the Junkers L5 engine.
F 13bi, ci, di, fi: models incorporating a 186 kW (250 hp) BMW IV engine.
F 13co, fo, ko: variants driven by a 230 kW (310 hp) BMW Va engine.
Junkers-Larsen JL-6: American-manufactured variant produced by Junkers-Larsen with eight units built.
Junkers-Larsen JL-12: An armed ground-attack adaptation of the JL-6, equipped with a 300 kW (400 hp) Liberty L-12 engine and reinforced armor including a downward-firing array of thirty Thompson submachine guns.
Rimowa Junkers F 13: Contemporary reproduction that first flew on 15 September 2016. Sanctioned by the Junkers family and rebranded as Junkers Flugzeugwerke AG based in Altenrhein. It integrates modern avionics while preserving the traditional aesthetic reminiscent of the Junkers-Larsen JL-6.

Operators

(post-1926)

Afghan Air Force procured four units between 1924 and 1928.

Argentine Air Force operated a fleet of three aircraft.

Austrian Air Force (1927-1938)
Österreichische Luftverkehrs AG (ÖLAG) utilized twenty-four F 13 aircraft.

SNETA

Lloyd Aéreo Boliviano received its inaugural F 13 as a commemorative gift from Bolivia's German community in honor of the country's centennial independence.

Bulgarian Air Force
Bunavad operated two aircraft during the period from 1927 to 1928.

Chilean Air Force

Avianca (formerly SCADTA)
Colombian Air Force

Free City of Danzig

Aeronaut operated F 13 aircraft from 1922 until 1927.

Junkers Luftverkehr, principal operator until its merger with Deutscher Aero Lloyd forming Deutsche Luft Hansa
Deutsche Luft Hansa managed approximately one hundred ten aircraft, many inherited from Junkers Luftverkehr.

Aero R.T. flew six aircraft between 1923 and 1927.
Aeroexpress Rt. operated from 1923 to 1930
Royal Hungarian Air Force

Air Iceland employed three aircraft between 1928 and 1931.

Imperial Iranian Air Force

Latvijas Gaisa Satiksmes Akciju Sabiedriba utilized three aircraft from 1922 to 1925.

Lithuanian Air Force briefly used one aircraft which crash-landed after unauthorized border crossing in 1919.

Mexican Air Force

Mongolian People's Army Air Force operated three aircraft from 1925 through 1931.

Aero-Targ leased six units from Danziger Luftpost during 1921.
Aerolloyd, later renamed as Aerolot, flew sixteen aircraft between 1922 and 1929.
LOT Polish Airlines inherited fifteen remaining Aerolot aircraft and continued operation until 1936.

Serviços Aéreos Portugueses operated one unit between 1929 and 1931.

Deruluft
Aviaarktika operated several units.
Soviet Air Force

South African Airways flew four aircraft acquired from Union Airways.
South African Air Force

Ad Astra Aero operated at least four F 13s (registrations CH-91/92/93/94) between approximately 1919 and circa 1930.

Turkish Air Force flew three aircraft from 1925 to 1933.
Turkish Air Post utilized two former military aircraft between 1933 and 1938.
The General Command of Mapping (Turkey) operated one ex-military aircraft outfitted with aerial photography equipment from 1933 to 1938.

Civil aviation registers document five F 13s active during the 1930s

Accidents and incidents

On 1 September 1920, a Junkers-Larsen JL-6 experienced a fire and crashed near Morristown, New Jersey. Max Miller, the inaugural pilot for the United States Air Mail Service, along with mechanic Gustav Reierson, perished after successfully ejecting all nine mail bags.
A SCADTA F 13 stalled during takeoff from Barranquilla, Colombia, on 8 June 1924, resulting in a crash that claimed the lives of all five individuals onboard.
On 10 March 1926, a Latvijas Gaisa Satiksmes F 13 flying for Aero O/Y crashed while approaching Helsinki, though no fatalities occurred.
A Zakavia F 13 crashed during takeoff from Tiflis, Georgia, on 22 March 1925. The accident resulted in five fatalities, including three senior Soviet officials who were traveling to meet Trotsky.
On 24 July 1926, adverse weather conditions caused a Deutsche Luft Hansa F 13 to crash at Juist, Germany, killing all four passengers and crew.
A SCADTA F 13 collided with terrain between Honda and La Victoria, Colombia, on 3 September 1926. The crash injured two crew members and two passengers while destroying the aircraft.
Following engine failure, a Deutsche Luft Hansa F 13 made an emergency landing at Amöneburg, Germany, on 27 July 1927; all five occupants died in the crash.
Pilot error led to the crash of a Deutsche Lufthansa Junkers F 13 at Hahnenberg, Germany, on 26 May 1928. Three of the five people onboard lost their lives.
Structural failure caused a Walcot Air Line F 13 to crash near Gravesend, Kent on 21 July 1930; all six onboard were killed, including Lieutenant Colonel George L P Henderson.
Czech industrialist Tomáš Baťa and pilot Jindrich Broucek died in a Junkers J13 crash shortly after takeoff in dense fog on 12 July 1932.
On 2 November 1932, wing separation resulted in a Deutsche Luft Hansa F 13 crashing at Echterspfahl, Germany; all five occupants died.
The aircraft registered CF-ALX "City of Prince George" crashed into a tree during takeoff in the Canadian wilderness on 23 July 1933; the wreckage was recovered in 1981 for museum restoration.
An Aero O/Y F 13 crashed into the Gulf of Finland amid fog on 9 October 1935, causing six fatalities.

Survivors

Currently, five Junkers F 13 airframes remain intact and are exhibited in various museums.

Aircraft exhibited

Part of the reserve collection at Musée de l'Air et de l'Espace, Le Bourget, Paris, France
Displayed at the Deutsches Museum in Munich, Germany
Exhibited within the Transport Museum of Budapest, Hungary
SE-AAC, formerly D-343, located at Tekniska museet, Stockholm, Sweden
Preserved at the Tomas Bata Memorial in Zlín, Czech Republic

Stored or undergoing restoration

Wrecked aircraft held at Deutsches Technikmuseum Berlin, Germany

Related developments

Bibliography

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Andersson, Lennart. "Talkback". Air Enthusiast, No. 18, April – July 1982. p. 80.
Andersson, Lennart. "Round-Out". Air Enthusiast, March–April 1999, Issue 80, p. 80.
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"All-metal Junkers airplane, type F 13". National Advisory Committee for Aeronautics, May 1926.

External links

Junkers F13 at the Hugo Junkers Homepage
Photographs of Junkers F 13 from the Budapest Aviation Museum