Junkers A50 Junior


The Junkers A50 Junior is a German all-metal sports plane first produced by Junkers in 1929. A modernized version, produced since 2022 by Junkers Aircraft Works, features updated materials, safety systems, and avionics.
Designed by Hermann Pohlmann during the late 1920s, it incorporated the all-metal construction and various other principles practiced on Junkers' larger aircraft of the era. The A50 had a streamlined fuselage composed of corrugated duralumin, a low-mounted cantilever wing, and proportionally large flight control surfaces. It could be outfitted with conventional landing gear, skis or floats to suit a variety of different operational conditions; the aircraft was reportedly suitable for use in the tropics or near-arctic conditions as well as from austere airstrips. It was typically powered by a single Armstrong Siddeley Genet II engine, although other powerplants could also be fitted.
In 1930, a floatplane variant of the Junkers A50 Junior set eight Fédération Aéronautique Internationale world records for altitude, distance, and average speed. In 1931, German aviator Marga von Etzdorf became the first woman to fly solo from Berlin to Tokyo, completing the journey in a Junkers A50 Junior, the first woman to do so.

Development

The Junkers A50 was the first sports plane designed by Hermann Pohlmann in Junkers works. It had the same modern all-metal construction, covered with corrugated duralumin sheet, as larger Junkers passenger planes. On 13 February 1929, the A50 conducted its maiden flight. Four additional prototypes followed, several equipped with different engines for testing.
Junkers expected to produce 5,000 aircraft, but halted manufacturing only 69 A50s, only 50 of which were ever sold. Sales remained modest; the aircraft was priced between £840 and £885 in 1930. Apart from Germany, they were used in several other countries and some were used by airlines. The purchase price in 1930 in the United Kingdom was between £840 and £885. Starting from the A50ce variant, the wings could be folded for easier transport.
Three Junkers A50 participated in the Challenge International touring plane competition, placing 11th and 17th. At the Challenge 1930, three A50 competed again, achieving 15th, 27th, and 29th place rankings. In June 1930, a series of eight FAI world records for altitude, range and average speed were set on a floatplane variant of A50, powered by the Armstrong Siddeley Genet II 59 kW engine. During 1931, Marga von Etzdorf flew an A50 solo from Berlin to Tokyo, the first woman to do so.

Design

The Junkers A50 was a sports plane that featured a conventional configuration, all-metal construction, a low-mounted cantilever wing, and a stressed corrugated duralumin exterior. It was promoted for its adaptability, being as equally suitable for use during summer as it was during the winter, on land or at sea, and in the tropics or near-arctic conditions. The A50 conformed with several conventions for Junkers-built aircraft, such as the placement of the pilot in the rear seat while the passenger sat in the forward position. Both positions were provided with dual flight controls and two complete sets of instruments.
The fuselage was a precisely streamlined tube of corrugated duralumin; in spite of its extensive use of metal, it was carefully designed so that it achieved the typical weight limits of mixed-construction aircraft. It was supported by a number of formers and bulkheads that had provisions for easy access that permitted both inspection and repairs to be performed. The nose of the fuselage accommodated the aircraft's single engine while the rear of the fuselage tapered into a vertical wedge that extended upwards to form the fin.
Having been designed to serve as a touring aircraft, several aspects of the aircraft, such as the comfort and convenience of the occupants, were addressed in detail. The two seats present in the cockpit, used by the pilot and a single passenger, were relatively well-upholstered, broad, and fitted with an adjustable back and arm rests. Two separate baggage compartments were provided for the carriage of even particularly heavy suitcases; one, positioned between the two seats, was within easy reach of either occupant throughout the flight. The second baggage compartment, behind the pilot's seat, was large enough for a single streamer trunk. Piping in the vicinity of the cockpit was concealed by the aircraft's double bottomed fuselage.
The wing was divided into a central section, which was integral with the fuselage, and two outer sections that were joined to the centre using no more than four screws each; this aided ground transportation as well as repair work, the outer sections being readily replicable by a substitute. Akin to the fuselage, the wing was covered in stressed corrugated duralumin. Structurally, it was relatively simplistic, dispensing with many typical supporting devices, such as ribs; this simplicity benefitted both production and service staff alike. Several mundane defects, such as bulges, were felt to be reasonably addressable by the owner themselves. For more space-efficient storage of the aircraft, the wings could be folded rearwards on some models.
It had a two-part elevator that was hinged to the stabilisor; it could be adjusted while on the ground. The rudder was hinged to both the fin and the tip
of the fuselage. The elevator, rudder and ailerons all used ball bearings, which were relatively easy to operate and service. The aircraft's proportionally large flight control surfaces, thus only necessitating slight deflections, were actuated using a series of adjustable push rods. The forces and deflections of the control stick and rudder bar were harmonised. Contemporary reviews highlighted the A50 Junior’s handling qualities, noting its suitability for pilot training.
The aircraft could be alternatively furnished with either conventional landing gear, skis or floats without the use of any special fittings. The floats were relatively large, to the extent that the aircraft could remain afloat if only one of them were to be attached; to maximise buoyancy in the even of damage, the floats had internal bulkheads that formed multiple water-tight compartments. Whichever undercarriage was opted for, it would be attached to supporting points underneath the centre section of the wing. The landing gear had a relatively wide track, which reduced the likelihood of the winds making contact with the ground, and lacked a continuous axle, which hindered ground movements in the presence of long grass or undergrowth. The rudder effectively offset the traditional manoeuvrability penalty incurred by the use of wide track landing gear. The wheels were relatively large and sturdy, and thus suitable for use on unprepared or austere airstrips. Furthermore, the landing gear was furnished with rubber-cable style shock absorbers that were designed for durability.
It was typically powered by a single Armstrong Siddeley Genet II air-cooled radial engine, which was mounted on an easily-removable frame upon the forward bulkhead, which functioned as a firewall. It possessed considerable reserve power and reliability, which led to its selection to power the aircraft. The engine was enclosed by smooth sheet duralumin that left only the cylinder heads exposed. The propeller was directly-driven by the engine. A special starter that involved the injection of atomized fuel into the intake manifold and a light magneto. Fuel was stored in two primary tanks in the centre section of the aircraft; it was supplied to a single gravity tank via a fuel pump. The oil tank was directly adjacent to the gravity tank.

New production

In 2022, Junkers Aircraft Works began production of a modernized version of the A50 known as the A50 Junior. This new A50 features modern avionics, a Rotax 912iS engine driving a composite MT-Propeller, and a ballistic parachute. As of May 2023, 27 new A50s have sold in Europe, and plans have been made for WACO Aircraft Corporation to produce aircraft for American customers.
During the 2024 Sun 'n Fun Aerospace Expo, Junkers unveiled the A50 Heritage. The A50 Heritage is marketed as a more authentic version closer to the original A50. It is powered by a Verner Scarlett 7U radial engine and features a two-piece glass windscreen and analog instruments.

Variants

Original production

  • A50 - Armstrong Siddeley Genet radial engine
  • A50ba - Walter Vega radial engine
  • A50be - Armstrong Siddeley Genet engine
  • A50ce - Armstrong Siddeley Genet II engine or for export Genet Major I 74 kW, folding wings
  • A50ci - Siemens-Halske Sh 13, radial engine, folding wings. Originally designed to be mass-produced as a "Volksflugzeug".
  • A50fe - Armstrong Siddeley Genet II, engine, modified airframe, folding wings
  • KXJ1 - A single Junkers A-50 supplied to the Imperial Japanese Navy Air Service for evaluation.
The -ce and -ci variants were produced in the largest numbers with about 25 of each on the German civil register. Due to their construction, the A50 were durable aircraft and they lasted long in service. The last plane was used in the 1960s in Finland. There is one A50 preserved in Deutsches Museum in Munich and another in Helsinki airport. One A50 is in airworthy condition in Australia.

New production