Junkers F 13

https://en.wikipedia.org/wiki/Junkers_F_13

The Junkers F 13 was the world's first all-metal transport aircraft, developed
in Germany at the end of World War I. It was an advanced cantilever-wing
monoplane, with enclosed accommodation for four passengers. 322 planes of the
type were manufactured, an exceptionally large number for a commercial airliner
of the era, and were operated all over the globe. It was in production for
thirteen years and in commercial service for more than thirty.

Design and development

The F 13 was a very advanced aircraft when built, an aerodynamically clean
all-metal low-wing cantilever (without external bracing) monoplane. Even later
in the 1920s, it and other Junkers types were unusual as unbraced monoplanes in
a biplane age, with only Fokker's designs of comparable modernity. It was the
world's first all-metal passenger aircraft and Junkers' first commercial
aircraft.

The designation letter F stood for Flugzeug, aircraft; it was the first Junkers
aeroplane to use this system. Earlier Junkers notation labelled it J 13.
Russian-built aircraft used the designation Ju 13.

Like all Junkers duralumin-structured designs, from the 1918 J 7 to the 1932 Ju
46, (some 35 models), it used an aluminium alloy (duralumin) structure entirely
covered with Junkers' characteristic corrugated and stressed duralumin skin.
Internally, the wing was built up on nine circular cross-section duralumin spars
with transverse bracing. All control surfaces were horn balanced.

Behind the single engine was a semi-enclosed cockpit for the crew, roofed but
without side glazing. There was an enclosed and heated cabin for four passengers
with windows and doors in the fuselage sides. Passenger seats were fitted with
seat belts, unusual for the time. The F 13 used a fixed conventional split
landing gear with a rear skid, though some variants landed on floats or on skis.

The F 13 first flew on 25 June 1919, powered by a 127 kW (170 hp) Mercedes D
IIIa inline upright water-cooled engine. The first production machines had a
wing of greater span and area and had the more powerful 140 kW (185 hp) BMW IIIa
upright inline water-cooled motor.

Many variants were built using Mercedes, BMW, Junkers, and Armstrong Siddeley
Puma liquid-cooled inline engines, and Gnome-Rhône Jupiter and Pratt & Whitney
Hornet air-cooled radial engines. The variants were mostly distinguished by a
two letter code, the first letter signifying the airframe and the second the
engine. Junkers L5-engined variants all had the second letter -e, so type -fe
was the long fuselage -f airframe with a L5 engine.


Role
small passenger transport

Manufacturer
Junkers

Designer
Otto Reuter

First flight
June 25, 1919

Introduction
1920

Retired
late 1930s

Primary users
Junkers Luftverkehr
DLH, LAB, LOT, ÖLAG

Produced
1919–1932

Number built
322

Operational history

Any manufacturer of civil aircraft immediately after World War I was faced with
competition from the very large numbers of surplus warplanes that might be
cheaply converted – for example, the DH.9C. German manufacturers had further
problems with the restrictions imposed by the Inter-Allied Aeronautical
Commission of Control, which banned the production of warplanes and of any
aircraft in the period of 1921–2. Junkers picked up orders abroad in 1919 in
Austria, Poland and the USA and, in the following years with SCADTA (Colombia)
and the United States Post Office Department. John Larsen Aircraft in the USA
purchased a production licence, their machines being designated JL-6. In 1922
there were sales in England, France Italy and Japan.

In Bolivia, LAB's first airplane was a Junkers F-13; first flight took off from
Cochabamba on September 23, 1925.

Junkers set up its own airline – Junkers Luftverkehr AG in 1921 – to encourage
the acquisition of the F 13 by German airlines which was flying 60 of them by
1923. They also established a branch of this airline in Iran. Other marketing
techniques were used, providing F 13s on cheap leases and free loans, with such
effect that some 16 operators across Europe were flying them. When Junkers
Luftverkehr merged into Luft Hansa in 1926, 9.5 million miles had been flown by
them. Luft Hansa itself bought 55 aircraft and in 1928 were using them on 43
domestic routes. Even in 1937, their F 13s were flying over 50 flights per week
on four routes. They were finally withdrawn in 1938.

Most of the F 13s produced before completion of the marque in 1932 were built at
Junkers German base at Dessau. During the difficult 1921–3 period production was
transferred to Junkers plants at Danzig and Reval. In 1922–3, Hugo Junkers
signed a contract with the Soviet Union to produce the aircraft in a Soviet
factory at Fili near Moscow which became known as "Plant no. 22". Some of these
aircraft served Soviet airlines and some the Red Army.

A feature that made the F 13 popular internationally was the ease with which its
landing gear could be converted to floats. During the formative years of
commercial aviation, bodies of water such as rivers, lakes, seas and oceans were
more abundant than landing strips and civil airports in many parts of the world,
so seaplanes were commonplace and even, in some places, more useful than regular
aircraft. Aside from the obvious addition of floats, little modification was
needed for this conversion; however, the different configuration could cause
issues with directional control, and so some models had their rudder extended to
compensate for this.

From their introduction in 1919, commercial F 13s were in service for more than
thirty years; the last commercial F 13 was retired in Brazil in 1951.

Back in Production 2009-2019

Junkers F13 Replica 'HB-RIM' Sep. 2019 Airport Moenchengladbach (MGL), Germany
A German-Swiss project to build a reconstruction of the F 13 was launched in
2009; the aircraft first lifted off in September 2016. The reconstruction is
equipped with radio and a transponder, and uses a 1930s Pratt & Whitney R-985
Wasp Junior motor, but is otherwise as close as possible to the original.
Additional reconstructions are to be sold for $2.5 million apiece.

Junkers Flugzeugwerke (SD303) has resurrected the Junkers F 13 as an all-new
airplane to honor Hugo Junkers’ achievements. The company completed the aircraft
in 2016 and it is at EBACE commemorating the type's maiden flight 100 years ago.
The model is available for purchase, and three others like it are currently
under construction. Work is currently in progress on the second and third
aircraft, with airframe number two's maiden flight planned for early this
summer.

Specifications (F 13)

General characteristics
Crew: two
Capacity: four passengers or 689 kg (1,519 lb) payload
Length: 9.59 m (31 ft 6 in)

F 13fe: 10.50 m (34 ft)Wingspan: 14.8 m (48 ft 7 in)

F 13fe: 17.75 m (58 ft)Height: 3.50 m (11 ft 6 in)

F 13fe: 3.60 m (12 ft)Wing area: 34.50 m2 (371.4 sq ft)

F 13fe: 44 m2 (474 sq ft)Empty weight: 951 kg (2,097 lb)

F 13fe: 1,480 kg (3,263 lb)Max takeoff weight: 1,640 kg (3,616 lb)

F 13fe: 2,318 kg (5,110 lb)Powerplant: 1 × Mercedes D.IIIa 6-cyl.water-cooled
in-line piston engine, 118 kW (158 hp)

F 13fe: 1 x 228 kW (306 hp) Junkers L5 6-cyl. water-cooled in-line piston engine

Performance

Maximum speed: 173 km/h (107 mph, 93 kn)

F 13fe: 198 km/h (123 mph)Cruise speed: 160 km/h (99 mph, 86 kn)

F 13fe: 170 km/h (106 mph)Range: 1,400 km (870 mi, 760 nmi)
Service ceiling: 5,000 m (16,000 ft)

F 13fe: 5,090 m (16,699 ft)Rate of climb: 2.40 m/s (472 ft/min)
Power/mass: 0.0712 kW/kg (0.0443 hp/lb)


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