The Fieseler Fi 156 Storch (, "stork") is a liaison aircraft designed and produced by the German aircraft manufacturer Fieseler. Its nickname of Storch was derived from the lengthy legs of its main landing gear, which gave the aircraft a similar appearance to that of the long-legged, big-winged bird.
Developed during the mid 1930s in response to a request from the Reichsluftfahrtministerium (Reich Aviation Ministry or RLM), the Fi 156 was an affordable and easy to construct aircraft purpose designed for the liaison, army co-operation, and medical evacuation roles. On 24 May 1936, the Fi 156 V1 performed its maiden flight; the first deliveries took place less than a year later. It was well regarded for its excellent short field (STOL) performance and low stalling speed of 50 km/h (31 mph). Around 2,900 aircraft of various models, the most commonplace being the Fi 156C, were produced between 1937 and 1945. The Fi 156 quickly became popular on the export market, eventually being widely used by various nations.
Numerous countries deployed their aircraft in a military capacity across various theatres of the Second World War. The Fi 156 was extensively operated by the Luftwaffe, who often used it in the aerial reconnaissance role and less often as a troop transport. German aircraft saw action on the Eastern Front, Western Front, the Western Desert, and even the Arctic. During September 1943, the Storch played a pivotal role in Operation Eiche, the rescue of deposed Italian dictator Benito Mussolini from a boulder-strewn mountain-top near the Gran Sasso. On 26 April 1945, a Storch was one of the last aircraft to land on the improvised airstrip in the Tiergarten near the Brandenburg Gate during the Battle of Berlin. During the conflict, several Störche were captured by the Allies; several were used as the personal aircraft of high ranking officers such as Field Marshal Bernard Montgomery, Air Vice Marshal Arthur Coningham, and Air Vice Marshal Harry Broadhurst.
Even after the end of the conflict, production of the type continued in other countries into the 1950s, both for the private market and military operators. In addition to Germany, additional production lines had been established in France, Czechoslovakia, Romania, and the Soviet Union. Furthermore, there have been many attempts to recreate or imitate the Fi 156, including several three-quarter scale homebuilt aircraft, such as the Pazmany PL-9 Stork, RagWing RW19 Stork, and STOL King. The Slepcev Storch and French-built later variants of the original aircraft have often appeared at air shows and other flying events. Numerous flight-worthy aircraft are still operational into the twenty-first century.
Development Background and selection During 1935, the Reichsluftfahrtministerium (Reich Aviation Ministry or RLM) issued in invitation to several aviation companies to submit their proposals for a new aircraft for the Luftwaffe that was to be suitable for the roles of liaison, army co-operation (today called forward air control), and medical evacuation. The German aircraft manufacturer Fieseler quickly took an interest in the new requirement and opted to produce its own clean sheet design, which was largely conceived of by chief designer Reinhold Mewes and technical director Erich Bachem. This new aircraft, which was subsequently assigned the Fi 156 designation, was specifically designed to achieve particularly strong short take off and landing ("STOL") performance.
In addition to Fieseler's submission, competing proposals were submitted from various other aircraft manufacturers, including Weser Flugzeugbau and Siebel in the form of the Bf 163 and Si 201 respectively.Smith and Kay 1972, p. 142. While the Bf 163 broadly resembled the Fi 156, the Si 201 was a relatively unorthodox aircraft; all three designs were evaluated in depth by officials. The Fi 156 emerged as the favoured submission, in part due to its relatively cheap and straightforward construction offered in its design.
On 24 May 1936, the Fi 156 V1, registered D-IKVN, performed its maiden flight; it was quickly followed by a further four prototypes. From an early stage, the company had envisioned two different production versions, the Fi 156A and Fi 156B, the latter having movable leading edge slots instead of the formers' fixed slot arrangement. The first production standard aircraft were delivered in early 1937.
German production About 2,900 Fi 156s, the majority being of the Fi 156C model, were produced between 1937 and 1945. The principal production line was at the Fieseler Factory in Kassel. During 1942, production started in the Morane-Saulnier factory at Puteaux in France. Due to the demand for Fieseler as a subcontractor for building the Fw 190, Fi 156 production was shifted to Leichtbau Budweis in Budweis by the end of 1943. Factories in other countries under German control manufactured aircraft, including Fi 156s, for Germany.
Soviet production In 1939, after the signing of the Molotov–Ribbentrop Pact, Germany provided several aircraft, including the Fi 156C, to the Soviet Union. Oleg Antonov was made responsible for putting the aircraft into production to meet Soviet requirements, and given a choice between designing an equivalent aircraft or copying the German design, the latter was selected. The aircraft was titled OKA-38 and two versions were envisaged: the SS three seat liaison aircraft, and the N-2 air ambulance capable of carrying two stretchers plus a medic. A prototype was constructed in Factory No. 365, established on the basis of Lithuanian Military Aviation Works, in Kaunas, recently occupied Lithuania. The first prototype was built in Factory No. 23 in Leningrad and flew before the end of 1940. Production in Kaunas had just started when the factory was lost to the German advance in 1941. While Antonov's efforts had produced a heavier aircraft, which required as much as three times the field for landing and take off as the German Fi 156C (160 m vs 55 m), it also had much greater range and increased load capability. After the conflict, Antonov went on to design the legendary An-2 STOL biplane, which also has excellent STOL performance.
Production in Czechoslovakia In 1944, production was moved from the Leichtbau Budweis to the Mráz factory in Choceň which produced 138 examples of the Fi 156, locally designated as "K-65 Čáp" (i.e. stork in Czech). Production ended during 1949.
Production in France
During the Second World War, the French manufacturer Morane-Saulnier was operated under German control, during which time it built German types including the Storch. Immediately after the liberation of France in 1944, the production of the Fi 156 at the Morane-Saulnier factory was continued at the request of the Armée de l'Air. The resulting batch of aircraft produced with the remaining stock of Argus air-cooled inverted V8 engines were designated MS 500 Criquet. Aircraft with further modifications and different engines (inline and radial) received various different type numbers. The use of the aircraft in Indochina highlighted the weakness of wood for the construction of the airframe; thus it was decided to build the wings out of metal instead. Among the modifications, the defensive weapon aiming through the back window was dropped, although some aircraft were modified in the field to take a MAC 34T machine gun firing through one of the side windows. Some 141 aircraft were built before the end of the Second World War while a total of 925 aircraft were built before the end of the production of all types of Criquet by Morane-Saulnier in 1965.
Production in Romania Licence production was started in Romania in October 1943 at the ICAR factory in Bucharest. Only 10 were built by the time the ICAR factory was bombed in May 1944. Production resumed later that year, but only six were completed before repair work halted production. Between June 1945 and 1946, a further 64 aircraft were built.Axworthy et al. 1995, pp. 249–250.
Summary of production Production per factory and per type until 31 March 1945:
Type Fieseler Morane-Saulnier Mraz Leichtbau Total A-010 10 B-014 14 B-136 36 C-1286 286 C-2239 239 C-31,230525 1,755 C-7 2593263354 D-1117 117 D-2 461056 Total 1,908 784 78 73 2,867
Modern developments
Because of its superb STOL characteristics, there have been many attempts to recreate or copy the Storch, mainly in the form of various three-quarter scale homebuilt aircraft, such as the Pazmany PL-9 Stork, Roger Mann's RagWing RW19 Stork, and Preceptors STOL King.
As an example, the Slepcev Storch is a three-quarter scale reproduction of the original with some simplifications. The use of modern materials provides better STOL performance than the original with a take-off run of 30 m and landing-roll of 50 m with no headwind. It was originally designed and manufactured in Australia and is now manufactured in Serbia.
Design
The Fieseler Fi 156 Storch was a high-wing monoplane that was particularly effective at short take off and landing ("STOL"). Its nickname of Storch was derived from the lengthy legs of its main landing gear, which hung down during flight and gave the aircraft the appearance of a long-legged, big-winged bird. As a product of its relatively low landing speed, the Storch often gave the appearance of landing vertically, or even backwards, when flying directly into strong winds. The aircraft was typically crewed by three personnel seated with its enclosed cabin, which was extensively glazed as to provide generous external views.Smith and Kay 1972, pp. 142-143. The structure was composed of welded steel tubing while the covering was fabric. Both the tail unit and wings were composed of wood, the latter being clad in plywood.Smith and Kay 1972, p. 143.
The Fi 156 had relatively lengthy wings for its size. A fixed slat ran along the entire length of the wing's leading edge while a hinged and slotted set of control surfaces ran along the entire length of trailing edge. This arrangement was allegedly inspired by an earlier Junkers wing design concept, referred to as a Doppelflügel or "double-wing" aircraft wing control surface. On the Fi 156, this setup along each wing panel's trailing edge was split nearly 50/50 between the inboard-located flaps and outboard-located ailerons, which, in turn, included trim tab devices over half of each aileron's trailing edge length. This combination of flaps and slats has been heavily attributed for the aircraft's favourable STOL performance.Smith and Kay 1972, p. 145.
An uncommon feature for land-based aircraft was the ability to fold back the wings of the aircraft along the fuselage, which was somewhat similar to the wings of the Royal Navy's Fairey Swordfish torpedo bomber; when folded, the aircraft could be carried on a trailer or even directly towed (albeit slowly) behind a vehicle. The primary hinge for the folding wing was located in the wing root, where the rear wing spar met the cabin.
The long legs of the main landing gear were furnished with both oil and spring-based shock absorbers that had a travel of 40 cm (15-3/4 inches), sufficient to permit landings on comparatively rough and uneven surfaces; this was combined with a "pre-travel" distance of 20 cm, before the oleos began damping the landing gear shock.
While initial models were unarmed, starting with the C-2 variant, the Fi 156 was fitted with a raised, fully-glazed position for a flexible rear-firing MG 15 7.92mm machine gun for self-defense.
Operational history Second World War