Nazi Germany (1934)
Dive-bomber – 262-400 Built

Prior to the Second World War, the Germans were experimenting with how to increase the accuracy of air bombing attacks. One solution was to use dive attacks, which greatly increased the chance of hitting the desired targets. By the mid-30s, a number of German aircraft manufacturing companies were experimenting with planes that could fulfill these dive bomb attacks. The Junkers Ju 87 proved to be the most promising design and would be adopted for service.  The Ju 87 would become one of most iconic aircraft of the Second World War, being feared for its precise strikes, but also for its unique use of sirens for psychological warfare.

History

After the First World War, the Germans began experimenting with ideas on how to make aircraft more precise during ground attack operations. The use of conventional bombers that dispatched their payload from straight and level flight could effectively engage larger targets, such as urban centers, industrial facilities, infrastructure, etc. This method was less effective for destroying smaller targets, like bunkers or bridges. A dive-attack, on the other hand, provided a greater chance of hitting smaller targets and, to some extent, reduced the chance of being shot down by ground based enemy anti-aircraft fire. This concept of dive-attack aircraft would be studied and tested in detail by the Germans during the 1930s. These aircraft would be known as Sturzkampfbomber (dive-bomber), but generally known as Stukas. 

The development of such aircraft was greatly hindered by the prohibitions imposed by the Treaty of Versailles. To overcome this, some German companies simply opened smaller subsidiaries in other countries. In the case of the Junkers, a subsidiary company known as Flygindustri was opened in Sweden. There, they developed a K 47 two-seater fighter in 1929. It was tested for the role of dive-bomber and proved successful. But its price was too high for the German Luftwaffe to accept, so it was rejected.

As a temporary solution, the Germans adopted the He 50 in 1932. The following year, a more comprehensive test of the dive-bombing concept was undertaken at airbase Juterbog-Damm. During these trials, Ju-52 bombers were used. The overall results were disappointing, thus development of a completely new dedicated design was prioritized by the Germans. For this, Luftwaffe officials placed an order with all aircraft manufacturers to present their models for the dive-bomber competition.

In late 1933, the Junkers dive-bomber development project was carried out by engineer Herman Pohlmann. He stressed the importance of an  overall robust aircraft design in order to be able to withstand steep diving maneuvers. Additionally, it should have had fixed landing gear and be built using all-metal construction. 

The next year, a fully completed wooden mock-up with inverted gull wings and twin tail fins was built by Junkers. Officials from the German Aviation Ministry (Reichsluftfahrtministerium RLM) inspected the mock-up during late 1934, but they were not impressed and didn’t place a production order. Despite this, Junkers continued working on the project. Junkers soon began construction of a full scale prototype. Due to many delays with the design, construction of the project dragged into October 1935. The first prototype received the Ju 87 V1 designation, bearing serial number 4921. Somewhat surprisingly, it was powered by a 640 hp Rolls-Royce Kestrel 12 cylinder engine. The first test flight was completed in September 1935 by test pilot Willi Neuenhofen. While the first flight was generally successful, the use of a foreign engine was deemed unsatisfactory and it was requested that a domestic built engine be used instead.  The V1 prototype would be lost in an accident when one of the twin tail fins broke off during a dive test near Dresden. Both the pilot Willi Neuenhofen and the second passenger, engineer Heinrich Kreft, lost their lives. The examination of the wreckage showed that the fin design was too weak and thus had to be replaced with a simple conventional tail fin. 

Ju 87 V2 (serial number 4922 and with tail code  D-UHUH (later changed to D-IDQR) was built with the 610 hp Jumo 210 A engine and had a redesigned tail fin. Another addition was the installation of special slats that could be rotated at 90° forward, perpendicular to the underside of the wing, acting as dive brakes. The V2 also received a specially designed bomb release mechanism, meant to avoid accidentally hitting the lowered radiator and the propeller. When the pilot activated the bomb release during a dive, the specially designed cradle would simply swing forward. In essence, this catapulted the bomb safely away from the plane while still maintaining its trajectory toward the target. There were a number of delays with the redesign of the airframe, which led to V2’s first flight being made during late February 1936. While the test flight was successful, the Luftwaffe officials showed some reluctance with regards to the project, given the fate of the first prototype. Nevertheless, the Ju 87, together with the He 118, Ha 137 and Ar 81, were used in a dive-bomber competition. The initial results favored the Heinkel, but when the He 118 was lost during one of its  test flights together with the engine problems, the RLM proclaimed the Ju 87 as the winner.

Winning the competition for the new dive-bomber design, Junkers was instructed to build more prototypes to improve the overall performance of the Ju 87. The V3 (serial number 4923 and designation D-UKYQ) received a number of modifications. It had an enlarged tailfin, added counterweights on the elevators, a modified landing gear, and a redesigned engine cowl to improve forward visibility. The first test flight was made in March of 1936. 

The V4 (serial number 4924 and with D-UBIP) was further modified by once again increasing the size of the tailfin, adding forward firing machine guns, a rear defensive machine gun, and again redesigning the front engine compartment. It was powered by the Jumo 210 Aa engine. It was flight tested for the first time in June 1936. During its test flight, the maximum cruising speed achieved was 250 km/h (155 mph). The RLM would become increasingly concerned about the Ju 87 design, as this cruising speed was the same as that of the older He 50. Despite this, the handling and resilience of the whole airframe were deemed satisfactory. The V4 prototype would later serve as the base for the A-0 pre-production series. The last prototype, V5 (serial number 4925), was built in May 1936. It was built to test the installation of the DB 600 and Jumo 210 engines. 

The Ju 87 ‘Anton’ Introduction

Following the success of the prototype series, the RLM officials issued orders for more Ju 87 aircraft. This would lead to a small production run of between 7 to 10 aircraft of the Ju 87A-0 pre-series aircraft (A for Anton, according to the German phonetic alphabet). While the first A-0 aircraft were to be built starting in November 1935, due to a number of delays, the actual production began in the spring of 1936. Following a series of tests conducted on the A-0 aircraft at the end of 1936, it was determined that these planes, equipped with the Jumo 210 Aa engine, were underpowered. A number of the A-0 aircraft would receive a new 680 hp Jumo 210 D engine as an upgrade. The A-0’s rear fuselage was also lowered to provide the rear gunner with a better firing arc. For the radio equipment, two ‘V’ shaped antennas were placed around the cockpit. 

Further development led to the Ju 87A-1, which was powered by the Jumo 210 D as standard. The A-1 series was able to carry one 250 kg (550 lbs) bomb in its standard two man crew configuration. Alternatively, it could carry one 500 kg (1100 lbs) bomb but, in this case, the rear machine gunner had to be left behind. 

The last version of the series was the Ju 87A-2. It was slightly improved by adding better radio equipment. In addition, the engine performance was improved, along with a new two-stage compressor, and a new propeller.

Technical Characteristics 

The Ju 87A was designed as a single-engined, twin-seat all metal dive bomber. Its fuselage was built by connecting two oval-shaped sections with a simple structure design. The longerons consisted of long shaped strips which spanned across the longitudinal direction of the aircraft. These had a ‘U’ shape which was connected to the duralumin skin by rivets. 

For construction of the Ju 87’s wings, Junkers engineers employed the doppelüger (a double wing construction). This meant that the full-span ailerons were hinged near the trailing edge of the wings. Another feature of the wings was that they had an inverted gull design. This was done intentionally by the Junkers engineers in an attempt to provide the crew members with the best possible all around visibility. The Ju 87 fuselage and wings were covered with a combination of duralumin and magnesium alloy sheeting. While the V1 prototype was equipped with twin tail fins, the A-series was equipped with a more orthodox tail design. The tailplanes had a rectangular shape, while the rudder had a square shape.

The landing gear was fixed. It consisted of two larger front wheels, with one smaller tailwheel to the rear. The front landing gear and wheels were covered in large protective fairings, sometimes known as “spats.” This arrangement would prove to be problematic, and would later be replaced with a much simpler design.

The Ju 87 engine was mounted specifically to provide easy access for replacement or maintenance. It was powered by an inline Jumo 210 D water cooled engine, with a variable pitch propeller with a 3.3 m diameter. The fuel capacity was 480 liters, placed in two tanks. The fuel tanks were located in the center part of the curved wings. 

The Ju 87 had a large cockpit where the pilot and the rear gunner were positioned in a back-to-back configuration. The center of the canopy assembly was reinforced by a durable section of cast magnesium, meant to provide better structural integrity. The cockpit was also protected with a fire-resistant asbestos firewall. On the A-series, the pilot was responsible for operating the radio equipment. This task would be allocated to the rear gunner in later versions. The radio equipment consisted of a FuG VII radio receiver and transmitter. 

The Ju 87A-1 was armed with one forward mounted 7.92 mm MG 17 and a rear positioned MG 15, also firing 7.92 mm, fitted on a flexible mount. The offensive armament consisted of either a 250 kg or 500 kg bomb (550 to 1100 lbs). When the larger bomb was used, the rear crew member had to be left behind. A small number of aircraft were equipped with bomb racks for four 50 kg (110 lbs)  mounted under the wings. These were actually used for training purposes, as the bombs were actually made of concrete. 

Diving Operation

The Ju 87 pilot would commence the dive-bombing run once the target was identified. The target would be located through a bombsight which was placed in the cockpit floor. The attack would usually be carried out from an altitude of less than 4,600 meters. The aircraft would then be rolled around by the pilot until it was upside down. The Ju 87 would then engage its target at an angle of attack of 60 to 90°, with a speed of 500 to 600 km/h (310-370 mph). During these dive-bombing runs, there was a chance the pilot could  temporarily lose consciousness due to extensive G-forces. If the pilot was unable to pull up, a ground collision was a strong possibility. To avoid this, the Ju 87 was equipped with automatic dive brakes that would simply level out the plane at a safe altitude. Once the plane reached a level flight, the brakes would then disengage. The Ju 87 was also equipped with warning lights that informed the pilot when it was time to release the bomb. 

Germans conducted extensive research to determine how much G-force a pilot could endure without any medical problems. The testing revealed that the pilot could overcome a 4G force without problems. At 5G , the pilot would experience blurred vision. The maximum G-forces were noted to be 8.5 G but only for three seconds. Any more could lead to extensive injuries or even death. 

Organization

The Ju 87 were used to equip the so-called Sturzkampfgeschwader or simply StG (dive-bomber flight unit). The StG was divided into three Gruppen (groups). Each of these groups was further divided into three Staffel (squadrons).  

In Combat

The Ju 87 saw its first combat action during the Spanish Civil War that lasted from 1936 to 1939. The Germans saw this war as the perfect place to test their new aircraft designs. For this reason, one V4 prototype was secretly disassembled and transported on a passenger ship to Spain in August 1936. It was part of the experimental unit (Versuchskommando) VK/88 (or VJ/88, depending on the source) of the Condor Legion. The overall performance or even the use of this aircraft is generally unknown. During this conflict, it received the designation 29-1. It may have taken part in the Battle of Bilbao  in June of 1937, after which it was shipped back to Germany. 

In early 1938, three more aircraft of the A-1 series were shipped to Spain. These received the 29-2, 29-3, and 29-4 designations. They were given to the 1st Staffel of Sturzkampfgeschwader  162 (dive bomber wing).  While only three aircraft were used by this unit  their original designations were often replaced with higher numbers in an atempt to decive the enemy.  The initial pilots of these aircraft were Ernst Bartels, Hermann Hass, and Gerhard Weyert. The Germans would replace them with new crew members after some time, in the hope of increasing the number of pilots with experience operating the aircraft under combat situations. 

Their initial base of operations was an airfield near Zaragoza, Spain. There were some problems with the forward landing gear covers, which would dig into the ground on the sandy soil of the airfield. To resolve this issue, the crews simply removed them. The use of a larger 500 kg bomb required the removal of the rear gunner, so the smaller 250 kg bomb load was more frequently used.

In March 1938,, the three Ju 87s attempted to attack retreating Spanish Republican units at the Aragon with somewhat limited success. The attacks were less successful, mainly due to the inexperience of the pilots. From July 1938 on, the Ju 87 showed more promising performance during the Spanish Republican failed counterattack at the Ebro River and Mequinenza. By October, all three Ju 87 As were shipped back to Germany. 

The overall performance of the A-series was deemed insufficient for combat operations early on. This, together with the fact that the improved Ju 87B version was becoming available in increasing numbers, leading to a withdrawal of the A version from service. These would be reallocated to training units, and would be used in this role up to 1944. 

In Hungarian Service 

During the war the Germans provided their Hungarian ally with four Ju 87A aircraft. These were used mostly for crew training in later stages of the war. 

Production and Modifications

Production of the Ju 87 ended by the summer of 1938. By that time, some 262 were built by the Junkers factories located in Dessau (192) and Bremen (70). These numbers are according to M. Griehl (Junkers Ju 87 Stuka). Author D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka), on the other hand, notes a number of 400 aircraft being built. 

The main versions were:

• Ju 87 Prototype series – Five prototypes were built and used mostly for testing. 
• Ju 87A-0 – A small pre-production series.
• Ju 87A-1 – Main production version.
• Ju 87A-2 – Slightly improved A-1 aircraft.

Conclusion

While the Ju 87A fulfilled the role of dive-bomber well, it was shown to be inadequately developed to meet military requirements. For this reason, it was mainly issued for crew training. Its main success was that it provided the German with an excellent base for improvement and development of further aircraft. It also provided the German pilots with valuable experience in such dive-bombing flights.

Ju 87A-1  Specifications
Wingspans	45 ft 3 in / 13.8 m
Length	35 ft 4 in / 10.78 m
Height	12 ft 9  in  /  3.9 m
Wing Area	104 ft² /  31.9 m²
Engine	Junkers Jumo 210D 680 hp engine
Empty Weight	5,070 lbs / 2,300 kg
Maximum Takeoff Weight	7,500 lbs / 3,400 kg
Fuel Capacity	480 liters / 127 US gallons
Maximum Speed	200 mph / 320 km/h
Cruising speed	170 mph  / 275 km/h
Range	620 miles / 1,000 km
Maximum Service Ceiling	22,970 ft / 7,000 m
Crew	One pilot and the Rear Gunner
Armament	One forward mounted 7.92 mm MG17 and one 7.92 mm MG15 positioned to the rear One 550 lb (250 kg) bomb for two-seaster Or one  1100 lb (500 kg) bomb in the single-seater configuration.

Gallery

Illustrations by Carpaticus

Credits

• Article by Marko P.
• Edited by Stan L. & Ed J.
• Illustrations by David Bocquelet & Carpaticus
• M. Griehl (2006) Junkers Ju 87 ‘Stuka’, AirDOC.
• M. Guardia (2014) Junkers ju 87 Stuka, Osprey Publishing 
• D. Nešić (2008). Naoružanje Drugog Svetsko Rata-Nemačka. Tampoprint S.C.G. Beograd.
• D. Monday. (2006). The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
• Z. Bašić (2018) Građanski Rat U španiji 1936-1939, Čigoja Štampa. 
• G. Sarhidai, H. Punka and V. Kozlik. (1996) Hungarian Air Forces 1920-1945, Hikoki Publisher