The Arado Ar 231 was a lightweight floatplane, developed during World War II in Germany as a scout plane for submarines by Arado. The need to be stored inside the submarine necessitated compromises in design that made this single-seat seaplane of little practical use.
The Göppingen Gö 1 Wolf was a single-seat glider produced in Germany from 1935.
The Aero A.42 was a Czechoslovakian bomber aircraft of 1929 that was only ever produced in prototype form. For its day, it was an advanced design, with a sleek monoplane configuration. However, the Czechoslovak Air Force was not satisfied with it for a number of reasons. In particular, the aircraft's take-off and landing runs were felt to be excessively long, and crew complained about the cramped cabin. The air force suggested a set of modifications to Aero, including replacing the wooden wing with a metal one, but Aero discontinued development.
The Arado SSD I was a biplane fighter seaplane developed in Germany in 1930, intended to be launched from catapults on warships. This was an all-new design from Walter Rethel, sharing nothing with his other fighter designs for Arado of the late 1920s. It was a conventional unequal-span, staggered biplane, with the slightly gulled top wing attached to the upper fuselage. It was equipped with a single, large float under the fuselage and two outrigger floats near the wingtips. After evaluation at Travemünde, the floats were removed and a simple, wheeled undercarriage was fitted for competitive evaluation with the Heinkel HD 38 at Lipetsk. The Heinkel was selected, and the SSD I was relegated to trainer duties with the LVS in 1932.
The Loire 70 was a 1930s French long-range maritime reconnaissance flying boat produced by Loire Aviation.
The Fieseler Fi 97 was a 1930s German four-seat cabin touring and competition monoplane aircraft designed and built by the German manufacturer Fieseler.
The Focke-Wulf A 38 Möwe was an airliner, produced in Germany in the early 1930s. It was a final development of the family of designs that commenced with the A 17 in 1927. The A 38 used the same high-mounted, cantilever wing as the A 29, but mated this to an all-new fuselage design with enclosed seating for ten passengers and three crew. Unlike earlier members of the family, the flight deck was not joined to the cabin, separated now by a lavatory and baggage compartment. The main undercarriage was strengthened and the mainwheels fitted with brakes, while the tailskid was replaced with a tailwheel. All four A 38s were originally fitted with Siemens- or Gnome et Rhône-built Bristol Jupiter engines, but in April 1933, all aircraft were refitted with Siemens Sh 20 powerplants. By mid-1934, they had been relegated to training duties.
The Fokker D.XIII was a fighter aircraft produced in the Netherlands in the mid-1920s. It was a development of the Fokker D.XI with a new powerplant and considerably refined aerodynamics, and had been designed to meet the requirements of the clandestine flying school operated by the German Army at Lipetsk in the Soviet Union. Like its predecessor, it was a conventional single-bay sesquiplane with staggered wings braced by V-struts. The pilot sat in an open cockpit and the undercarriage was of fixed, tailskid type. The wings were made of wood and skinned with plywood, and the fuselage was built up of welded steel tube with fabric covering.
The Heinkel HD 38 was a fighter aircraft developed in Germany in the late 1920s. It was a compact, single-bay biplane with staggered wings of unequal span, braced with N-type interplane struts, a refined version of the HD 37 that had been evaluated and rejected by the Reichswehr for use at the secret training facility at Lipetsk. The HD 38 was designed in the hope of capturing a different niche - that of a seaplane fighter, and was designed with a twin pontoon undercarriage that could be quickly removed and replaced with wheels. It was accepted in this role, but did not serve in it for long before being relegated to general training duties. Even then, it was not long before Germany abandoned the Lipetsk base to the Soviet Union.
The SZD-59 Acro is a single-seat glass composite glider for aerobatics and cross-country flying by PZL Allstar of Bielsko-Biala, Poland.
The Dornier Do Y was a German bomber of the 1930s, the second bomber design by Dornier Flugzeugwerke.
The Klemm Kl 32 was a touring aircraft, developed in Germany in 1932, based on the Klemm Kl 31 as a competitor in the Challenge 1932 touring aircraft competition.
The Klemm Kl 105 was a two-seat sport aircraft developed in Germany in 1938. It was a low-wing cantilever monoplane of conventional design with fixed, tailskid undercarriage, and side-by-side seating for two within an enclosed cockpit. Construction throughout was of wood, with the fuselage built using a new semi-monocoque technique which Klemm patented. Plans to produce the design in series were abandoned with the outbreak of the Second World War.
The Lioré et Olivier LeO H-43 was a reconnaissance seaplane produced in France in the 1930s. It was a strut-braced, mid-wing monoplane of largely conventional design, provided with an observation balcony underneath the fuselage. It was designed to be launched by catapult from warships and, after a first flight in 1934, trials were conducted on board Commandant Teste.
The Messerschmitt M 28 was a mail plane developed in Germany in the early 1930s to meet a requirement by Deutsche Luft Hansa. It was a single-engine, low-wing cantilever monoplane of conventional design with an enclosed cockpit and fixed, tailskid undercarriage.
The Avia B.158 was a prototype Czechoslovak twin-engined light bomber aircraft of the 1930s. Only a single example was built and it was abandoned, following the German occupation of Czechoslovakia in March 1939.
The Avia 51 was a 1930s Czechoslovakian six-passenger commercial transport, designed by Robert Nebesář and built by Avia. The type was uneconomical in use and only three were built.
The Blériot 290 was a 1930s French sesquiplane flying-boat designed by Filippo Zappata, only one was built and it was not ordered into production.
The Breda Ba.46 was a three-engined Italian bomber transport, developed from a similar but lower-powered civil transport. It was designed in Italy in the mid-1930s for colonial policing but not put into production.
The Albatros L102 / Albatros Al 102, was a German trainer aircraft of the 1930s. It was a parasol-wing landplane, seating the student pilot and instructor in separate, open cockpits. A biplane floatplane version was also built as the Al 102W, with strut-braced lower wings.
