The Junkers Ju 87 or Stuka (from Sturzkampfflugzeug, "dive bomber") was a German dive bomber and ground-attack aircraft. Designed by Hermann Pohlmann, it first flew in 1935. The Ju 87 made its combat debut in 1937 with the Luftwaffe's Condor Legion during the Spanish Civil War. It served the Axis forces in World War II.
The aircraft was easily recognisable by its inverted gull wings and fixed spatted undercarriage. Upon the leading edges of its faired main gear legs were mounted the Jericho-Trompete ("Jericho trumpet") wailing sirens, becoming the propaganda symbol of German air power and the blitzkrieg victories of 1939–1942. The Stuka's design included several innovative features, including automatic pull-up dive brakes under both wings to ensure that the aircraft recovered from its attack dive even if the pilot blacked out from the high g-forces.
The Ju 87 operated with considerable success in the close air support and anti-shipping at the outbreak of World War II. It spearheaded the air assaults in the Invasion of Poland in September 1939 and the Norwegian Campaign in the following year. In May 1940, the Ju 87s were crucial in the rapid conquest of the Netherlands, Belgium and France against all targets. Although sturdy, accurate, and very effective against ground targets, the Ju 87, like many other dive bombers of the war, was vulnerable to modern fighter aircraft. During the Battle of Britain a lack of manoeuvrability, speed and defensive armament meant that the Stuka required a heavy fighter escort to operate effectively.
The Stuka operated with further success after the Battle of Britain, and its potency as a precision ground-attack aircraft became valuable to German forces in the Balkans Campaign, the African and Mediterranean theaters and the early stages of the Eastern Front where it was used for general ground support, but also in the anti-shipping role and as an effective specialised anti-tank aircraft.
Once the Luftwaffe lost air superiority, on all fronts, the Ju 87 again became an easy target for enemy fighter aircraft. Despite these developments, because there was no better replacement, the type continued to be produced until 1944. By the end of the conflict, the Stuka had been largely replaced by ground-attack versions of the Focke-Wulf Fw 190, but was still in use until the last days of the war. An estimated 6,500 Ju 87s of all versions were built between 1936 and August 1944.
Some notable airmen flew the Ju 87. Oberst Hans-Ulrich Rudel was the most successful Stuka ace and the most highly decorated German serviceman of the Second World War. The vast majority of German ground attack aces flew this aircraft at some point in their careers.
The Ju 87's principal designer, Hermann Pohlmann, held the opinion that any dive-bomber design needed to be simple and robust. This led to many technical innovations, such as the retractable undercarriage being discarded in favour of one of the Stuka's distinctive features, its fixed and "spatted" undercarriage. Pohlmann continued to carry on developing and adding to his ideas and those of Dipl Ing Karl Plauth (Plauth was killed in a flying accident in November 1927), and produced the Ju A 48 which underwent testing on 29 September 1928. The military version of the Ju A 48 was designated the Ju K 47.
; the greatest proponent of the dive-bomber and the Ju 87 (photo 1928)
After the Nazis came to power, the design was given priority. Despite initial competition from the Henschel Hs 123, the Reichsluftfahrtministerium (RLM, the German aviation ministry) turned to the designs of Herman Pohlmann of Junkers and co-designer of the K 47, Karl Plauth. During the trials with the K 47 in 1932, the double vertical stabilisers were introduced to give the rear gunner a better field of fire. The main, and what was to be the most distinctive, feature of the Ju 87 was its double-spar inverted gull wings. After Plauth's death, Pohlmann continued the development of the Junkers dive bomber. The Ju A 48 registration D-ITOR, was originally fitted with a BMW 132 engine, producing some 450 kW (600 hp). The machine was also fitted with dive brakes for dive testing. The aircraft was given a good evaluation and "exhibited very good flying characteristics".
Ernst Udet took an immediate liking to the concept of dive-bombing after flying the Curtiss F11C Goshawk. When he invited Walther Wever and Robert Ritter von Greim to watch Udet perform a trial flight in May 1934 at the Jüterbog artillery range, it raised doubts about the capability of the dive bomber. Udet began his dive at 1,000 m (3,300 ft) and released his 1 kg (2.2 lb) bombs at 100 m (330 ft), barely recovering and pulling out of the dive. The chief of the Luftwaffe Command Office, Walther Wever, and Secretary of State for Aviation Erhard Milch, feared that such high-level nerves and skill could not be expected of "average pilots" in the Luftwaffe. Nevertheless, development continued at Junkers. Udet's "growing love affair" with the dive bomber pushed it to the forefront of German aviation development. Udet went so far as to advocate that all medium bombers should have dive-bombing capabilities, which initially doomed the only dedicated, strategic heavy bomber design to enter German front-line service during the war years — the 30 meter wingspan He 177A — into having an airframe design (due to Udet examining its design details in November 1937) that could perform "medium angle" divebombing missions, until Reichsmarschall Hermann Göring exempted the He 177A, Germany's only operational heavy bomber, in September 1942 from being given the task of such a mismatched mission profile for its 30-meter wingspan airframe.
The design of the Ju 87 had begun in 1933 as part of the Sturzbomber-Programm. The Ju 87 was to be powered by the British Rolls-Royce Kestrel engine. Ten engines were ordered by Junkers on 19 April 1934 for £ 20,514, two shillings and sixpence. The first Ju 87 prototype was built by AB Flygindustri (sv) in Sweden and secretly brought to Germany in late 1934. It was to have been completed in April 1935, but, due to the inadequate strength of the airframe, construction was not completed until October 1935. However, the mostly complete Ju 87 V1 W.Nr.c 4921 (less non-essential parts) took off for its maiden flight on 17 September 1935. The aircraft originally did not carry any registration, but later was given the registration D-UBYR. The flight report, by HauptmannWilly Neuenhofen, stated the only problem was with the small radiator, which caused the power plant to overheat.
The Ju 87 V1, powered by a Rolls-Royce Kestrel V12 cylinder liquid-cooled engine, and with a twin tail, crashed on 24 January 1936 at Kleutsch near Dresden, killing Junkers' chief test pilot, Willy Neuenhofen, and his engineer, Heinrich Kreft. The square twin fins and rudders proved too weak; they collapsed and the aircraft crashed after it entered an inverted spin during the testing of the terminal dynamic pressure in a dive. The crash prompted a change to a single vertical stabiliser tail design. To withstand strong forces during a dive, heavy plating was fitted, along with brackets riveted to the frame and longeron, to the fuselage. Other early additions included the installation of hydraulic dive brakes that were fitted under the leading edge and could rotate 90°.
The most notable feature of the Stuka was its inverted gull wings, as shown in this photograph. Also visible are the two separate sliding "hoods" of the canopy.
The RLM was still not interested in the Ju 87 and was not impressed that it relied on a British engine. In late 1935, Junkers suggested fitting a DB 600 in-line engine, with the final variant to be equipped with the Jumo 210. This was accepted by the RLM as an interim solution. The reworking of the design began on 1 January 1936. The test flight could not be carried out for over two months due to a lack of adequate aircraft. The 24 January crash had already destroyed one machine.
The second prototype was also beset by design problems. It had its twin stabilizers removed and a single tail fin installed due to fears over stability. Due to a shortage of power plants, instead of a DB 600, a BMW "Hornet" engine was fitted. All these delays set back testing until 25 February 1936. By March 1936, the second prototype, the V2, was finally fitted with the Jumo 210Aa power plant, which a year later was replaced by a Jumo 210 G (W.Nr. 19310). Although the testing went well, and the pilot, Flight Captain Hesselbach, praised its performance, Wolfram von Richthofen told the Junkers representative and Construction Office chief engineer Ernst Zindel that the Ju 87 stood little chance of becoming the Luftwaffe's main dive bomber, as it was underpowered in his opinion. On 9 June 1936, the RLM ordered cessation of development in favour of the Heinkel He 118, a rival design. Udet cancelled the order the next day, and development continued.
On 27 July 1936, Udet crashed the He 118 prototype, He 118 V1 D-UKYM. That same day, Charles Lindbergh was visiting Ernst Heinkel, so Heinkel could only communicate with Udet by telephone. According to this version of the story, Heinkel warned Udet about the propeller's fragility. Udet failed to consider this, so in a dive, the engine oversped and the propeller broke away. Immediately after this incident, Udet announced the Stuka the winner of the development contest.