German Aircraft ” Junkers Ju 87 ” ( Dive Bomber Class )

Junkers Ju 87

Ju 87
Ju 87Ds in October 1943
Role	Dive bomber
Manufacturer	Junkers
Designer	Hermann Pohlmann
First flight	17 September 1935
Introduction	1936
Retired	1945 (Luftwaffe)
Primary users	Luftwaffe Regia Aeronautica Royal Romanian Air Force Bulgarian Air Force
Number built	Estimated 6,500[a]

The Junkers Ju 87 or Stuka (from Sturzkampfflugzeug, “dive bomber“) is 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 and 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 Stuka operated with considerable success in 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. Stukas were crucial in the rapid conquest of Norway, the Netherlands, Belgium and France in 1940. Although sturdy, accurate, and very effective against ground targets, the Stuka was vulnerable to contemporary fighter aircraft, like many other dive bombers of the war. During the Battle of Britain its lack of manoeuvrability, speed and defensive armament meant that it required a heavy fighter escort to operate effectively. After the Battle of Britain the Stuka took part in the Balkans Campaign, the African and Mediterranean theatres and the early stages of the Eastern Front where it was used for general ground support, as an effective specialised anti-tank aircraft and in an anti-shipping role. Once the Luftwaffe lost air superiority, the Stuka became an easy target for enemy fighter aircraft on all fronts. It was produced until 1944 for lack of a better replacement. By then ground-attack versions of the Focke-Wulf Fw 190 had largely replaced the Stuka, but Stukas remained in service until the end of the war.

An estimated 6,500 Ju 87s of all versions were built between 1936 and August 1944.

Oberst Hans-Ulrich Rudel was the most successful Stuka ace and the most highly decorated German serviceman of the Second World War.

Development

Early design

The Ju 87’s principal designer, Hermann Pohlmann, held the opinion that any dive-bomber design needed to be simple and robust.^[1] 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.^[1]

Ernst Udet; 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.^[2] 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 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”.^[1]

Ernst Udet took an immediate liking to the concept of dive-bombing after flying the Curtiss F11C Goshawk. When Walther Wever and Robert Ritter von Greim were invited 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.^[3] The chief of the Luftwaffe Command Office Walther Wever, and the 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.^[3] Nevertheless, development continued at Junkers.^[3] Udet’s “growing love affair” with the dive bomber pushed it to the forefront of German aviation development.^[4] Udet went so far as to advocate that all medium bombersshould have dive-bombing capabilities,^[5] which initially doomed the only dedicated, strategic heavy bomber design to enter German front-line service during the war years — the 30-metre wingspan He 177A — into having an airframe design (due to Udet examining its design details in November 1937) that could perform “medium angle” dive-bombing 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 large airframe.^[6]

Evolution

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.^[7] 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 took until October 1935. 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 was later given the registration D-UBYR.^[8] The flight report, by HauptmannWilly Neuenhofen, stated the only problem was with the small radiator, which caused the engine to overheat.^[9]

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.^[10] 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.^[11] 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°.^[12]

The Stuka had 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 inverted V-12 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 stabilisers removed and a single tail fin installed due to fears over stability. Due to a shortage of engines, instead of a DB 600, a BMW “Hornet” engine was fitted. All these delays set back testing until 25 February 1936.^[13] By March 1936, the second prototype, the V2, was finally fitted with the Jumo 210Aa engine, 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.^[14]

On 27 July 1936, Udet crashed the He 118 prototype, He 118 V1 D-UKYM.^[15] 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.^[16] Immediately after this incident, Udet announced the Stuka the winner of the development contest.^[15]

Honing the design

Despite being chosen, the design was still lacking and drew frequent criticism from Wolfram von Richthofen. Testing of the V4 prototype (A Ju 87 A-0) in early 1937 revealed several problems. The Ju 87 could take off in 250 m (820 ft) and climb to 1,875 m (6,152 ft) in eight minutes with a 250 kg (550 lb) bomb load, and its cruising speed was 250 km/h (160 mph). Richthofen pushed for a more powerful engine.^[17] According to the test pilots, the Heinkel He 50 had a better acceleration rate, and could climb away from the target area much more quickly, avoiding enemy ground and air defences. Richthofen stated that any maximum speed below 350 km/h (220 mph) was unacceptable for those reasons. Pilots also complained that navigation and powerplant instruments were mixed together, and were not easy to read, especially in combat. Despite this, pilots praised the aircraft’s handling qualities and strong airframe.^[18]

These problems were to be resolved by installing the Daimler-Benz DB 600 engine, but delays in development forced the installation of the Jumo 210 D inverted V-12 engine. Flight testing began on 14 August 1936. Subsequent testing and progress fell short of Richthofen’s hopes, although the machine’s speed was increased to 280 km/h (170 mph) at ground level and 290 km/h (180 mph) at 1,250 m (4,100 ft), while maintaining its good handling ability.^[19]

Design

Basic design (based on the B series)

Junkers Jumo 211 inverted V12 powerplant on an aircraft undergoing repair (North Africa, 1941)

The Ju 87 was a single-engined all-metal cantilever monoplane. It had a fixed undercarriage and could carry a two-person crew. The main construction material was duralumin, and the external coverings were made of duralumin sheeting. Parts that were required to be of strong construction, such as the wing flaps, were made of Pantal (a German aluminium alloy containing titanium as a hardening element) and its components made of Elektron. Bolts and parts that were required to take heavy stress were made of steel.^[20]

The Ju 87 was fitted with detachable hatches and removable coverings to aid and ease maintenance and overhaul. The designers avoided welding parts wherever possible, preferring moulded and cast parts instead. Large airframe segments were interchangeable as a complete unit, which increased speed of repair.^[20]

Stuka engine and wing

The airframe was also subdivided into sections to allow transport by road or rail. The wings were of standard Junkers double-wing construction. This gave the Ju 87 considerable advantage on take-off; even at a shallow angle, large lift forces were created through the aerofoil, reducing take-off and landing runs.^[20]

In accordance with the Aircraft Certification Centre for “Stress Group 5”, the Ju 87 had reached the acceptable structural strength requirements for a dive bomber. It was able to withstand diving speeds of 600 km/h (370 mph) and a maximum level speed of 340 km/h (210 mph) near ground level, and a flying weight of 4,300 kg (9,500 lb). Performance in the diving attack was enhanced by the introduction of dive brakes under each wing, which allowed the Ju 87 to maintain a constant speed and allow the pilot to steady his aim. It also prevented the crew from suffering extreme g forces and high acceleration during “pull-out” from the dive.^[20]

The fuselage had an oval cross-section and housed a water-cooled inverted V-12 engine. The cockpit was protected from the engine by a firewall ahead of the wing centre section where the fuel tanks were located. At the rear of the cockpit, the bulkhead was covered by a canvascover which could be breached by the crew in an emergency, enabling them to escape into the main fuselage. The canopy was split into two sections and joined by a strong welded steel frame. The canopy itself was made of Plexiglas and each compartment had its own “sliding hood” for the two crew members.^[20]

The engine was mounted on two main support frames that were supported by two tubular struts. The frame structure was triangulated and emanated from the fuselage. The main frames were bolted onto the engine’s top quarter. In turn, the frames were attached to the firewall by universal joints. The firewall itself was constructed from asbestos mesh with dural sheets on both sides. All conduits passing through had to be arranged so that no harmful gases could penetrate the cockpit.^[21]

The fuel system comprised two fuel tanks between the main (forward) and rear spars of the (inner) anhedral wing section of the port and starboard wings, each with 240-litre (63 US gal) capacity.^[22] The tanks also had a predetermined limit which, if passed, would warn the pilot via a red warning light in the cockpit. The fuel was injected via a pump from the tanks to the engine. Should this shut down, it could be pumped manually using a hand-pump on the fuel cock armature.^[21] The powerplant was cooled by a 10-litre (2.6 US gal), ring-shaped aluminium water container situated between the propeller and engine. A further container of 20-litre (5.3 US gal) was positioned under the engine.^[21]

The control surfaces operated in much the same way as other aircraft, with the exception of the innovative automatic pull-out system. Releasing the bomb initiated the pull-out, or automatic recovery and climb, upon the deflection of the dive brakes. The pilot could override the system by exerting significant force on the control column and taking manual control.^[23]

The Ju 87 at the RAF Museum, London, with its wing outer sections temporarily detached, May 2016

The wing was the most unusual feature. It consisted of a single centre section and two outer sections installed using four universal joints. The centre section had a large negative dihedral (anhedral) and the outer surfaces a positive dihedral. This created the inverted gull, or “cranked”, wing pattern along the Ju 87’s leading edge. The shape of the wing improved the pilot’s ground visibility and also allowed a shorter undercarriage height. The centre section protruded by only 3 m (9 ft 10 in) on either side.^[23]

The offensive armament was two 7.92 mm (.312 in) MG 17 machine guns fitted one in each wing outboard of undercarriage, operated by a mechanical pneumatics system from the pilot’s control column. The rear gunner/radio operator operated one 7.92 mm (.312 in) MG 15 machine gun for defensive purposes.^[20]

The engine and propeller had automatic controls, and an auto-trimmer made the aircraft tail-heavy as the pilot rolled over into his dive, lining up red lines at 60°, 75° or 80° on the cockpit side window with the horizon and aiming at the target with the sight of the fixed gun. The heavy bomb was swung down clear of the propeller on crutches prior to release.^[24]

Diving procedure[edit]

Ju 87 diving procedure

Flying at 4,600 m (15,100 ft), the pilot located his target through a bombsight window in the cockpit floor. The pilot moved the dive lever to the rear, limiting the “throw” of the control column.^[25] The dive brakes were activated automatically, the pilot set the trim tabs, reduced his throttle and closed the coolant flaps. The aircraft then rolled 180°, automatically nosing the aircraft into a dive. Red tabs protruded from the upper surfaces of the wing as a visual indicator to the pilot that, in case of a g-induced black-out, the automatic dive recovery system would be activated. The Stuka dived at a 60-90° angle, holding a constant speed of 500–600 km/h (350-370 mph) due to dive-brake deployment, which increased the accuracy of the Ju 87’s aim.^[25]

When the aircraft was reasonably close to the target, a light on the contact altimeter came on to indicate the bomb-release point, usually at a minimum height of 450 m (1,480 ft). The pilot released the bomb and initiated the automatic pull-out mechanism by depressing a knob on the control column.^[25] An elongated U-shaped crutch located under the fuselage swung the bomb out of the way of the propeller, and the aircraft automatically began a 6g pullout.^[25]Once the nose was above the horizon, dive brakes were retracted, the throttle was opened, and the propeller was set to climb. The pilot regained control and resumed normal flight. The coolant flaps had to be reopened quickly to prevent overheating. The automatic pull-out was not liked by all pilots. Helmut Mahlke later said that he and his unit disconnected the system because it allowed the enemy to predict the Ju 87’s recovery pattern and height, making it easier for ground defences to hit an aircraft.^[26]

Physical stress on the crew was severe. Human beings subjected to more than 5g in a seated position will suffer vision impairment in the form of a grey veil known to Stuka pilots as “seeing stars”. They lose vision while remaining conscious; after five seconds, they black out. The Ju 87 pilots experienced the visual impairments most during “pull-up” from a dive.^[27]

Eric “Winkle” Brown RN, a British test pilot and Commanding Officer of No. 1426 Flight RAF (the captured enemy aircraft Flight), tested the Ju 87 at RAE Farnborough. He said of the Stuka, “I had flown a lot of dive-bombers and it’s the only one that you can dive truly vertically. Sometimes with the dive-bombers…maximum dive is usually in the order of 60 degrees.. When flying the Stuka, because it’s all automatic, you are really flying vertically… The Stuka was in a class of its own.”^[28]

G-force test at Dessau

Extensive tests were carried out by the Junkers works at their Dessau plant. It was discovered that the highest load a pilot could endure was 8.5g for three seconds, when the aircraft was pushed to its limit by the centrifugal forces. At less than 4g, no visual problems or loss of consciousness were experienced.^[29] Above 6g, 50% of pilots suffered visual problems, or “greyout”. With 40%, vision vanished altogether from 7.5g upwards and black-out sometimes occurred.^[30] Despite this blindness, the pilot could maintain consciousness and was capable of “bodily reactions”. After more than three seconds, half the subjects passed out. The pilot would regain consciousness two or three seconds after the centrifugal forces had dropped below 3g and had lasted no longer than three seconds. In a crouched position, pilots could withstand 7.5g and were able to remain functional for a short duration. In this position, Junkers concluded that ⅔ of pilots could withstand 8g and perhaps 9g for three to five seconds without vision defects which, under war conditions, was acceptable.^[31]During tests with the Ju 87 A-2, new technologies were tried out to reduce the effects of g. The pressurised cabin was of great importance during this research. Testing revealed that at high altitude, even 2g could cause death in an unpressurised cabin and without appropriate clothing. This new technology, along with special clothing and oxygen masks, was researched and tested. When the United States Army occupied the Junkers factory at Dessau on 21 April 1945, they were both impressed at and interested in the medical flight tests with the Ju 87.^[31]

Other designs

The concept of dive bombing became so popular among the leadership of the Luftwaffe that it became almost obligatory in new aircraft designs. Later bomber models like the Junkers Ju 88 and the Dornier Do 217 were equipped for dive bombing. The Heinkel He 177 strategic bomber was initially supposed to have dive bombing capabilities, a requirement that contributed to the failure of the design,^[32] with the requirement not rescinded until September 1942 by Reichsmarschall Hermann Göring.^[6]

Once the Stuka became too vulnerable to fighter opposition on all fronts, work was done to develop a replacement. None of the dedicated close-support designs on the drawing board progressed far due to the impact of the war and technological difficulties. So the Luftwaffe settled on the Focke-Wulf Fw 190 fighter aircraft, with the Fw 190F becoming the ground-attack version. The Fw 190F started to replace the Ju 87 for day missions in 1943, but the Ju 87 continued to be used as a night nuisance-raider until the end of the war.^[33]

Variants

Ju 87A

Formation of Ju 87A dive-bombers, with the A’s characteristic large wheel “trousers”, each having one transverse bracing strut

The second prototype had a redesigned single vertical stabiliser and a 610 PS (601.7 hp; 448.7 kW) Junkers Jumo 210 A engine installed, and later the Jumo 210Da. The first A series variant, the A-0, was of all-metal construction, with an enclosed cockpit under a “greenhouse” well-framed canopy; bearing twin radio masts on its aft sections, diagonally mounted to either side of the airframe’s planform centreline and unique to the -A version. To ease the difficulty of mass production, the leading edge of the wing was straightened out and the ailerons‘ two aerofoil sections had smooth leading and trailing edges. The pilot could adjust the elevator and rudder trim tabs in flight, and the tail was connected to the landing flaps, which were positioned in two parts between the ailerons and fuselage. The A-0 also had a flatter engine cowling, which gave the pilot a much better field of vision. In order for the engine cowling to be flattened, the engine was set down nearly 0.25 m (9.8 in). The fuselage was also lowered along with the gunner’s position, allowing the gunner a better field of fire.^[34]

The RLM ordered seven A-0s initially, but then increased the order to 11. Early in 1937, the A-0 was tested with varied bomb loads. The underpowered Jumo 210A, as pointed out by von Richthofen, was insufficient, and was quickly replaced with the Jumo 210D engine.^[34]

The A-1 differed from the A-0 only slightly.^[35] As well as the installation of the Jumo 210D, the A-1 had two 220 l (58 US gal; 48 imp gal) fuel tanks built into the inner wing, but it was not armoured or protected.^[35] The A-1 was also intended to be fitted with four 7.92 mm (0.312 in) MG 17 machine guns in its wings, but two of these – one per side – were omitted due to weight concerns; the pair that remained were fed a total of 500 rounds of ammunition, stored in the design’s characteristic transverse strut-braced, large-planform undercarriage “trousers”, not used on the Ju 87B versions and onward. The pilot relied on the Revi C 21C gun sight for the two MG 17s. The gunner had a single 7.92 mm (0.312 in) MG 15 machine gun, with 14 drums of ammunition, each containing 75 rounds. This represented a 150-round increase in this area over the Ju 87 A-0. The A-1 was also fitted with a larger 3.3 m (11 ft) propeller.^[35]

The Ju 87 was capable of carrying a 500 kg (1,100 lb) bomb, but only if not carrying the rear gunner/radio operator as, even with the Jumo 210D, the Ju 87 was still underpowered for operations with more than a 250 kg (550 lb) bomb load. All Ju 87 As were restricted to 250 kg (550 lb) weapons (although during the Spanish Civil War missions were conducted without the gunner).^[36]

The Ju 87 A-2 was retrofitted with the Jumo 210Da fitted with a two-stage supercharger. The only further significant difference between the A-1 and A-2 was the H-PA-III controllable-pitch propeller.^[37] By mid-1938, 262 Ju 87 As had been produced, 192 from the Junkers factory in Dessau, and a further 70 from Weser Flugzeugbau (“Weserflug” – WFG) in Lemwerder near Bremen. The new, more powerful, Ju 87B model started to replace the Ju 87A at this time.^[38]

Prototypes^[39]

• Ju 87 V1 : W.Nr 4921. Flown on 17 September 1935
• Ju 87 V2 : W.Nr 4922, registration D-IDQR. Flown on 25 February 1936. Flown again as registration D-UHUH on 4 June 1937
• Ju 87 V3 : W.Nr 4923. Flown on 27 March 1936
• Ju 87 V4 : W.Nr 4924. Flown on 20 June 1936
• Ju 87 V5 : W.Nr 4925. Flown on 14 August 1936

Production variants

• Ju 87 A-0 : Ten pre-production aircraft, powered by a 640 PS (471 kW or 632 hp) Jumo 210C engine.^[40]
• Ju 87 A-1 : Initial production version.
• Ju 87 A-2 : Production version fitted with an improved 680 PS (500 kW or 670 hp) Jumo 210E engine.

Ju 87B

Junkers Ju 87 B during the Battle of Stalingrad

The Ju 87 B series was to be the first mass-produced variant. A total of six pre-production Ju 87 B-0 were produced, built from Ju 87 An airframes.^[41] The first production version was the Ju 87 B-1, with a considerably larger engine, its Junkers Jumo 211D generating 1,200 PS (883 kW or 1,184 hp), and completely redesigned fuselage and landing gear, replacing the twin radio masts of the “A” version with a single mast mounted further forward on the “greenhouse” canopy, and much simpler, lighter-weight wheel “spats” used from the -B version onwards, discarding the transverse strut bracing of the “A” version’s maingear design. This new design was again tested in Spain, and after proving its abilities there, production was ramped up to 60 per month. As a result, by the outbreak of World War II, the Luftwaffe had 336 Ju 87 B-1s on hand.^[25]

The B-1 was also fitted with “Jericho trumpets”, essentially propeller-driven sirens with a diameter of 0.7 m (2.3 ft)^[42] mounted on the wing’s leading edge directly forward of the landing gear, or on the front edge of the fixed main gear fairing. This was used to weaken enemy morale and enhance the intimidation of dive-bombing. After the enemy became used to it they were withdrawn. The devices caused a loss of 20–25 km/h (10-20 mph) through drag.^{[citation needed]} Instead, some bombs were fitted with whistles on the fin to produce the noise after release.^[43] The trumpets were a suggestion from Generaloberst Ernst Udet (but some authors say the idea originated from Adolf Hitler).^[44]

The Ju 87 B-2s that followed had some improvements and were built in several variants that included ski-equipped versions (the B-1 also had this modification)^[45] and at the other end, with a tropical operation kit called the Ju 87 B-2 trop. Italy’s Regia Aeronautica received B-2s and named them the “Picchiatello”, while others went to the other members of the Axis, including Hungary, Bulgaria and Romania. The B-2 also had an oil hydraulic system for closing the cowling flaps. This continued in all the later designs.^[46]

Production of the Ju 87 B started in 1937. 89 B-1s were to be built at Junkers’ factory in Dessau and another 40 at the Weserflug plant in Lemwerder by July 1937. Production would be carried out by the Weserflug company after April 1938, but Junkers continued producing Ju 87 up until March 1940.^[47]

Ju 87R

A standard 300 litre drop tank from a Bf 109 – similar in appearance to those used by the Ju 87R.

A long range version of the Ju 87B was also built, known as the Ju 87R, the letter being an abbreviation for Reichweite, “(operational) range”. They were primarily intended for anti-shipping missions. The Ju 87R had a B-series airframe with an additional oil tank and fuel lines to the outer wing stations to permit the use of two 300 litres (79 US gal) standardised capacity under-wing drop tanks, used by a wide variety of Luftwaffe aircraft through most of the war. This increased fuel capacity to 1,080 litres (290 US gal) (500 litres in main fuel tank of which 480 litres were usable + 600 litres from drop tanks). To prevent overload conditions, bomb carrying ability was often restricted to a single 250 kg (550 lb) bomb if the aircraft was fully loaded with fuel. The Ju 87 R-1 had a B-1 airframe with the exception of a modification in the fuselage which enabled an additional oil tank. This was installed to feed the engine due to the increase in range with the extra fuel tanks.^[48]

A Ju-87 towing a DFS 230 over Italy

The Ju 87 R-2 had the same airframe as the B-2, and strengthened to ensure it could withstand dives of 600 km/h (370 mph). The Jumo 211D in-line engine was installed, replacing the R-1s Jumo 211A.^[48] Due to an increase in overall weight by 700 kg (1,500 lb), the Ju 87 R-2 was 30 km/h (19 mph) slower than the Ju 87 B-1 and had a lower service ceiling. The Ju 87 R-2 had an increased range advantage of 360 km (220 mi).^[47] The R-3 and R-4 were the last R variants developed. Only a few were built. The R-3 was an experimental tug for gliders and had an expanded radio system so the crew could communicate with the glider crew by way of the tow rope. The R-4 differed from the R-2 in the Jumo 211J powerplant.^[49]

The powerplant; a Jumo 211D installed in a Ju 87 B — the “Jericho Trumpet” siren housing is faired over on the maingear leg

Known prototypes^[50]

• Ju 87 V6 : W.Nr 0870027. Flown on 14 June 1937 (A-0 to B-0 conversion)
• Ju 87 V7 : W.Nr 0870028. Prototype of the Ju 87B, powered by a 1,000 PS (735 kW or 986 hp) Jumo 211A. Flown on 23 August 1937 (A-0 to B-0 conversion)
• Ju 87 V8 : W.Nr 4926. Flown on 11 November 1937
• Ju 87 V9 : W.Nr 4927. Flown on 16 February 1938 as D-IELZ. Flown again as WL-IELZ on 16 October 1939
• Ju 87 V15: W.Nr 0870321. Registration D-IGDK. Destroyed in a crash in 1942.
• Ju 87 V16: W.Nr 0870279. Stammkennzeichen code of GT+AX.
• Ju 87 V17 and Ju 87 V18 may never have been built.^[41]

Ju 87C

On 18 August 1937, the RLM decided to introduce the Ju 87 Tr(C). The Ju 87 C was intended to be a dive and torpedo bomber for the Kriegsmarine. The type was ordered into prototype production and available for testing in January 1938. Testing was given two months and was to begin in February and end in April 1938.^[51] The prototype V10 was to be a fixed wing test aircraft, while the following V11 would be modified with folding wings. The prototypes were Ju 87 B-0 airframes powered by Jumo 211 A engines.^[51] Owing to delays, the V10 was not completed until March 1938. It first flew on 17 March and was designated Ju 87 C-1.^[51] On 12 May, the V11 also flew for the first time. By 15 December 1939, 915 arrested landings on dry land had been made. It was found that the arresting gear winch was too weak and had to be replaced. Tests showed the average braking distance was 20–35 metres (66–115 ft).^[52] The Ju 87 V11 was designated C-0 on 8 October 1938. It was fitted out with standard Ju 87 C-0 equipment and better wing-folding mechanisms. The “carrier Stuka” was to be built at the Weserflug Company’s Lemwerder plant between April and July 1940.^[53]

Among the “special” equipment of the Ju 87 C was a two-seat rubber dinghy with signal ammunition and emergency ammunition. A quick fuel dump mechanism and two inflatable 750 L (200 US gal) bags in each wing and a further two 500 L (130 US gal) bags in the fuselage enabled the Ju 87 C to remain afloat for up to three days in calm seas.^[53] On 6 October 1939, with the war already underway, 120 of the planned Ju 87 Tr(C)s on order at that point were cancelled. Despite the cancellation, the tests continued using catapults. The Ju 87 C had a takeoff weight of 5,300 kg (11,700 lb) and a speed of 133 km/h (83 mph) on departure. The Ju 87 could be launched with a SC 500 kg (1,100 lb) bomb and four SC 50 kg (110 lb) bombs under the fuselage. The C-1 was to have two MG 17s mounted in the wing with a MG 15 operated by the rear gunner. On 18 May 1940, production of the C-1 was switched to the R-1.^[54]

Known prototypes^[50]

• Ju 87 V10: Registration D-IHFH (changed to Stammkennzeichen of TK+HD). W.Nr 4928. First flown 17 March 1938
• Ju 87 V11: Stammkennzeichen of TV+OV. W.Nr 4929. First flown 12 May 1938

Ju 87D

Despite the Stuka’s vulnerability to enemy fighters having been exposed during the Battle of Britain, the Luftwaffe had no choice but to continue its development, as there was no replacement aircraft in sight.^[55] The result was the D-series. In June 1941, the RLM ordered five prototypes, the Ju 87 V21–25. A Daimler-Benz DB 603 powerplant was to be installed in the Ju 87 D-1, but it did not have the power of the Jumo 211 and performed “poorly” during tests and was dropped.^[56] The Ju 87 D-series featured two coolant radiators underneath the inboard sections of the wings, while the oil cooler was relocated to the position formerly occupied by the single, undernose “chin” coolant radiator. The D-series also introduced an aerodynamically refined cockpit with better visibility and space.^[57] Armour protection was increased and a new dual-barrel 7.92 mm (.312 in) MG 81Z machine gunwith an extremely high rate of fire was installed in the rear defensive position. Engine power was increased again, the Jumo 211J now delivering 1,420 PS (1,044 kW or 1,400 hp).^[57]Bomb carrying ability was nearly quadrupled from 500 kg (1,100 lb) in the B-version to 1,800 kg (4,000 lb) in the D-version (max. load for short ranges, overload condition), a typical bomb load ranged from 500–1,200 kg (1,100–2,600 lb).^[58]

Kette of Ju 87 Ds in flight, October/November 1943

The internal fuel capacity of the Ju 87D was raised to 800 L (of which 780 L were usable) by adding wing tanks while retaining the option to carry two 300 L drop tanks.^[59] Tests at Rechlin-Lärz Airfield revealed it made possible a flight duration of 2 hours and 15 minutes. With an extra two 300 L (80 US gal) fuel tanks, it could achieve four hours flight time.^[57]

The D-2 was a variant used as a glider tug by converting older D-series airframes. It was intended as the tropical version of the D-1 and had heavier armour to protect the crew from ground fire. The armour reduced its performance and caused the Oberkommando der Luftwaffe to “place no particular value on the production of the D-2”.^[57] The D-3 was an improved D-1 with more armour for its ground-attack role. Some Ju 87 D-3s were designated D-3N or D-3 trop and fitted with night or tropical equipment.^[57] The D-4 designation applied to a prototype torpedo-bomber version, which could carry a 750–905 kg (1,653–1,995 lb) aerial torpedo on a PVC 1006 B rack – this setup would have had the capacity to carry the Luftorpedo LT 850, the German version of the well-proven Japanese Type 91 aerial torpedo of 848 kg (1,870 lb). The D-4 was to be converted from D-3 airframes and, in place of the carrier-specific Ju 87C series designs, operated from the aircraft carrier Graf Zeppelin.^[60] Other modifications included a flame eliminator and, unlike earlier D variants, two 20 mm MG 151/20 cannon, while the radio operator/rear gunner’s ammunition supply was increased by 1,000 to 2,000 rounds.^[61]

The Ju 87 D-5 was based on the D-3 design and was unique in the Ju 87 series as it had wings 0.6 metres (2-feet) longer than previous variants. The two 7.92 mm MG 17 wing guns were exchanged for more powerful 20 mm MG 151/20s to better suit the aircraft’s ground-attack role. The window in the floor of the cockpit was reinforced and four, rather than the previous three, aileron hinges were installed. Higher diving speeds were obtained of 650 km/h (400 mph) up to 2,000 m (6,600 ft). The range was recorded as 715 km (444 mi) at ground level and 835 km (519 mi) at 5,000 m (16,000 ft).^[58]

The D-6, according to “Operating instructions, works document 2097”, was built in limited numbers to train pilots on “rationalised versions”. Due to shortages in raw materials, it did not go into mass production.^[62] The D-7 was another ground attack aircraft based on D-1 airframes upgraded to D-5 standard (armour, wing cannons, extended wing panels), while the D-8 was similar to the D-7 but based on D-3 airframes.^[62] The D-7 and D-8 were both were fitted with flame dampers, and could conduct night operations.^[62]

Production of the D-1 variant started in 1941 with 495 ordered. These aircraft were delivered between May 1941 and March 1942. The RLM wanted 832 machines produced from February 1941. The Weserflug company was tasked with their production. From June to September 1941, 40 Ju 87 Ds were expected to be built, increasing to 90 thereafter.^[63]Various production problems were encountered. One of the planned 48 was produced in July. Of the 25 the RLM hoped for in August 1941, none were delivered.^[63] In September did the first two of the planned 102 Ju 87s came off the production lines.^[64] The shortfalls continued to the end of 1941. During this time, the WFG plant in Lemwerder moved production to Berlin. Over 165 Ju 87s had not been delivered and production was only 23 Ju 87 Ds per month out of the 40 expected. By the spring of 1942 to the end of production in 1944, 3,300 Ju 87s, mostly D-1s, D-2s and D-5s had been manufactured.^[64]

In January 1943, a variety of Ju 87 Ds became “test beds” for the Ju 87 G variants. At the start of 1943, the coastal Luftwaffe Erprobungsstelle test centre at Tarnewitz tested this combination from a static position. Oberst G. Wolfgang Vorwald noted the experiments were not successful, and suggested the cannon be installed on the Messerschmitt Me 410.^[65]Testing continued, and on 31 January 1943, Ju 87 D-1 W.Nr 2552 was tested by Hauptmann Hans-Karl Stepp near the Briansk training area. Stepp noted the increase in drag, which reduced the aircraft’s speed to 259 km/h (161 mph). Stepp also noted that the aircraft was also less agile than the existing D variants. D-1 and D-3 variants operated in combat with the 37 mm (1.5 in) BK 37 cannon in 1943.^[65]

Known prototypes

• Ju 87 V 21. Registration D-INRF. W.Nr 0870536. Airframe conversion from B-1 to D-1. First flown on 1 March 1941.
• Ju 87 V 22 Stammkennzeichen of SF+TY. W.Nr 0870540. Also airframe conversion from B-1 to D-1. First flown on 1 March 1941.
• Ju 87 V 23 Stammkennzeichen of PB+UB. W.Nr 0870542. Also airframe conversion from B-1 to D-1. First flown on 1 March 1941.
• Ju 87 V 24 Stammkennzeichen of BK+EE. W.Nr 0870544. Also airframe conversion from B-1 to D-1/D-4. First flown on 1 March 1941.
• Ju 87 V 25 Stammkennzeichen of BK+EF. W.Nr 0870530. Also airframe conversion from B-1 to D-4 trop. First flown on 1 March 1941.
• Ju 87 V 30, the only known prototype of the Ju 87 D-5. W.Nr 2296. First flown on 20 June 1943.
• Ju 87 V 26-28, Ju 87 V 31, and V 42-47 were experiments of unknown variants.^[50]

Ju 87G

Ju 87 G-1 “Kanonenvogel” with its twin Bordkanone 3.7 cm (1.46 in) underwing gun pods.

With the G variant, the ageing airframe of the Ju 87 found new life as an anti-tank aircraft. This was the final operational version of the Stuka, and was deployed on the Eastern Front.

The reverse in German military fortunes after 1943 and the appearance of huge numbers of well-armoured Soviet tanks caused Junkers to adapt the existing design to combat this new threat. The Henschel Hs 129B had proved a potent ground attack weapon, but its large fuel tanks made it vulnerable to enemy fire, prompting the RLM to say “that in the shortest possible time a replacement of the Hs 129 type must take place.”^[66] With Soviet tanks the priority targets, the development of a further variant as a successor to the Ju 87D began in November 1942. On 3 November, Erhard Milch raised the question of replacing the Ju 87, or redesigning it altogether. It was decided to keep the design as it was, but the power-plant was upgraded to a Junkers Jumo 211J, and two 30 mm (1.2 in) cannons were added. The variant was also designed to carry a 1,000 kg (2,200 lb) free-fall bomb load. Furthermore, the armoured protection of the Ilyushin Il-2 Sturmovik – a feature pioneered by the 1916-17 origin Junkers J.I all-metal sesquiplane of World War I Imperial Germany‘s Luftstreitkräfte – was copied to protect the crew from ground fire now that the Ju 87 would be required to conduct low level attacks.^[67]

Hans-Ulrich Rudel, a Stuka ace, had suggested using two 37 mm (1.46 in) Flak 18 guns, each one in a self-contained under-wing gun pod, as the Bordkanone BK 3,7, after achieving success against Soviet tanks with the 20 mm MG 151/20 cannon. These gun pods were fitted to a Ju 87 D-1, W.Nr 2552. The first flight of the machine took place on 31 January 1943, piloted by Hauptmann Hans-Karl Stepp.^[65] The continuing problems with about two dozen of the Ju 88P-1, and slow development of the Henschel Hs 129B-3, each of them equipped with a large, PaK 40-based, autoloading Bordkanone 7,5 7.5 cm (2.95 in) cannon in a conformal gun pod beneath the fuselage, meant the Ju 87G was put into production. In April 1943, the first production Ju 87 G-1s were delivered to front line units.^[65] The two 37 mm (1.46 in) Bordkanone BK 3,7 cannons were mounted in under-wing gun pods, each loaded with two six-round magazines of armour-piercing tungsten carbide-cored ammunition. With these weapons, the Kanonenvogel (“cannon-bird”), as it was nicknamed, proved very successful in the hands of Stuka aces such as Rudel. The G-1 was converted from older D-series airframes, retaining the smaller wing, but without the dive brakes. The G-2 was similar to the G-1 except for use of the extended wing of the D-5. 208 G-2s were built and at least a further 22 more were converted from D-3 airframes.^[68]

Only a handful of production Gs were committed in the Battle of Kursk. On the opening day of the offensive, Hans-Ulrich Rudel flew the only “official” Ju 87 G, although a significant number of Ju 87D variants were fitted with the 37 mm (1.46 in) cannon, and operated as unofficial Ju 87 Gs before the battle. In June 1943, the RLM ordered 20 Ju 87Gs as production variants.^[69] The G-1 later influenced the design of the Fairchild Republic A-10 Thunderbolt II, with Hans Rudel’s book, Stuka Pilot being required reading for all members of the A-X project.^[70]

Night-harassment variants

The Soviet Air Force practice of harassing German ground forces using antiquated Polikarpov Po-2 and R-5 biplanes at night to drop flares and fragmentation bombs, inspired the Luftwaffe to form its own Störkampfstaffeln (harassment squadrons). On 23 July 1942, Junkers offered the Ju 87 B-2, R-2 and R-4s with Flammenvernichter (“flame eliminators”). On 10 November 1943, the RLM GL/C-E2 Division finally authorised the design in directive No. 1117.^[71] This new equipment made the Ju 87 more difficult to detect from the ground in darkness.

Pilots were also asked to complete the new “Blind Flying Certificate 3”, which was especially introduced for this new type of operation. Pilots were trained at night, over unfamiliar terrain, and forced to rely on their instruments for direction. The Ju 87’s standard Revi C12D gunsight was replaced with the new Nachtrevi (“Nightrevi”) C12N. On some Ju 87s, the Revi 16D was exchanged for the Nachtrevi 16D. To help the pilot see his instrument panel, a violet light was installed.^[72] On 15 November 1942, the Auxiliary Staffel were created. By mid-1943, Luftflotte 1 was given four Staffeln while Luftflotte 4 and Luftwaffe Kommando Ost (Luftwaffe Command East) were given six and two respectively. In the first half of 1943, 12 Nachtschlachtgruppen (“night battle groups”) had been formed, flying a multitude of different types of aircraft, including the Ju 87, which proved itself ideally suited to the low-level slow flying needed.^[73]

Production

Despite teething problems with the Ju 87, the RLM ordered 216 Ju 87 A-1s into production and wanted to receive delivery of all machines between January 1936 and 1938. The Junkers production capacity was fully occupied and licensing to other production facilities became necessary. The first 35 Ju 87 A-1s were therefore produced by the Weser Flugzeugbau (WFG). By 1 September 1939, 360 Ju 87 As and Bs had been built by the Junkers factories at Dessau and Weserflug factory in Lemwerder near Bremen. By 30 September 1939, Junkers had received 2,365,196 Reichsmark (RM) for Ju 87 construction orders. The RLM paid another 243,646 RM for development orders. According to auditrecords in Berlin, by the end of the financial year on 30 September 1941, 3,059,000 RM had been spent on Ju 87 airframes.^[74] By 30 June 1940, 697 Ju 87 B-1s and 129 B-2s alone had been produced. Another 105 R-1s and seven R-2s had been built.^[74]

A Ju 87D during wing installation

The range of the B-2 was not sufficient, and it was dropped in favour of the Ju 87 R long-range versions in the second half of 1940. The 105 R-1s were converted to R-2 status and a further 616 production R-2s were ordered. In May 1941, the development of the D-1 was planned and was ordered into production by March 1942. The expansion of the Junkers Ju 88 production lines to compensate for the withdrawal of Dornier Do 17 production delayed production of the Ju 87 D. The Weserflug plant in Lemwerder experienced production shortfalls. This prompted Erhard Milch to visit and threaten the company into meeting the RLM’s Ju 87 D-1 requirements on 23 February 1942.^[75] To meet these demands, 700 skilled workers were needed.^[75] Skilled workers had been called up for military service in the Wehrmacht. Junkers were able to supply 300 German workers to the Weserflug factory, and as an interim solution, Soviet prisoners of war and Soviet civilians deported to Germany.^[75] Working around the clock, the shortfall was made good. WFG received an official commendation.^[75] By May 1942, demand increased further. Chief of Procurement General Walter Herthel found that each unit needed 100 Ju 87s as standard strength and an average of 20 per month to cover attrition. Not until June–December 1942 did production capacity increase, and 80 Ju 87s were produced per month.^[75]

By 17 August 1942, production had climbed rapidly after Blohm & Voss BV 138 production was scaled down and licence work had shut down at WFG. Production now reached 150 Ju 87 D airframes per month, but spare parts were failing to reach the same production levels. Undercarriage parts were in particularly short supply. Milch ordered production to 350 Ju 87s per month in September 1942. This was not achievable due to the insufficient production capacity in the Reich.^[75]

The RLM considered setting up production facilities in Slovakia. But this would delay production until the buildings and factories could be furnished with the machine tools. These tools were also in short supply, and the RLM hoped to purchase them from Switzerland and Italy. The Slovaks could provide 3,500–4,000 workers, but no technical personnel.^[76] The move would only produce another 25 machines per month at a time when demand was increasing. In October, production plans were dealt another blow when one of WFGs plants burned down, leaving a chronic shortage of tailwheels and undercarriage parts. Junkers director and member of the Luftwaffe industry council Carl Frytag reported that by January 1943 only 120 Ju 87s could be produced at Bremen and 230 at Berlin-Tempelhof.^[76]

Decline and end of production

After evaluating Ju 87 operations on the Eastern Front, Hermann Göring ordered production limited to 200 per month in total. General der Schlachtflieger (“General of Close-Support Aviation”) Ernst Kupfer decided continued development would “hardly bring any further tactical value”. Adolf Galland, a fighter pilot with operational and combat experience in strike aircraft, said that abandoning development would be premature, but 150 machines per month would be sufficient.^[76]

Two Junkers Ju 87 Ds near completion

On 28 July 1943, strike and bomber production was to be scaled down, and fighter and bomber destroyer production given priority. On 3 August 1943, Milch contradicted this and declared that this increase in fighter production would not affect production of the Ju 87, Ju 188, Ju 288 and Ju 290. This was an important consideration as the life expectancy of a Ju 87 had been reduced (since 1941) from 9.5 months to 5.5 months to just 100 operational flying hours.^[77] On 26 October, General der Schlachtflieger Ernst Kupfer reported the Ju 87 could no longer survive in operations and that the Focke-Wulf Fw 190F should take its place. Milch finally agreed and ordered the minimal continuance of Ju 87 D-3 and D-5 production for a smooth transition period.^[77] In May 1944, production wound down. 78 Ju 87s were built in May and 69 rebuilt from damaged machines. In the next six months, 438 Ju 87 Ds and Gs were added to the Ju 87 force as new or repaired aircraft. It is unknown whether any Ju 87s were built from parts unofficially after December 1944 and the end of production.^[77]

Overall, 550 Ju 87 As and B2s were completed at the Junkers factory in Dessau. Production of the Ju 87 R and D variants was transferred to the Weserflug company, which produced 5,930 of the 6,500 Ju 87s produced in total.^[78] During the course of the war, little damage was done to the WFG plant at Lemwerder. Attacks throughout 1940-45 caused little lasting damage and succeeded only in damaging some Ju 87 airframes, in contrast to the Focke-Wulf plant in Bremen.^[79] At Berlin-Tempelhof, little delay or damage was caused to Ju 87 production, despite the heavy bombings and large-scale destruction inflicted on other targets. The WFG again went unscathed. The Junkers factory at Dessau was heavily attacked, but not until Ju 87 production had ceased. The Ju 87 repair facility at the Wels aircraft works was destroyed on 30 May 1944, and the site abandoned Ju 87 links.^[80]