Junkers Ju 188
| Industry | Aerospace, Defense |
|---|---|
| Founded | 1895 |
| Founder | Hugo Junkers |
| Headquarters | Dessau , Germany |
The Junkers Ju 188 "Rächer" ("Avenger") represented a German Luftwaffe medium bomber designed for high performance during World War II, intended as the successor to the Junkers Ju 88. It delivered enhanced payload capacity and improved flight characteristics but saw limited production due to ongoing enhancements of the Ju 88 and shifting German manufacturing priorities toward fighter aircraft amid intensified Allied bombing campaigns.
Background
In 1936, Junkers entered both the Ju 85 and Ju 88 into the Luftwaffe’s competition for a new standardized high-speed Schnellbomber tactical bomber. These models shared many design elements, differing primarily in tail configuration: the Ju 85 featured twin vertical stabilizers, while the Ju 88 employed a single fin.
Alongside these, modified variants—the Ju 85B and Ju 88B—were introduced with a distinctive "stepless cockpit," characterized by a greenhouse-style forward fuselage composed of multiple curved window panels. This "bullet-nose" configuration, which became common in German bombers starting with the Heinkel He 111P, incorporated the under-nose Bola defensive gun position more seamlessly than previous designs. Despite its innovation, this cockpit style was initially considered too unconventional; as a result, the simpler Ju 88A with its stepped cockpit secured early production contracts due to reduced aerodynamic drag and improved pilot visibility.
The Reich Air Ministry (RLM) aimed to develop a faster bomber capable of higher altitudes and increased payload under the "Bomber B" initiative. However, progress was hindered by delays in producing reliable high-output engines such as Junkers' Jumo 222. Although the Junkers Ju 288 spearheaded Bomber B development, engine availability remained uncertain.
As a stopgap measure, Junkers revisited the Ju 88B concept by adapting the short-wing Ju 88 A-1 airframe to incorporate the new stepless cockpit and the recently tested Junkers Jumo 213 engine, rated at . This adaptation necessitated redesigning an annular radiator for effective engine cooling.
The RLM also required that the design be compatible with the BMW 801 radial engine housed within a modular Kraftei power-egg unit without modifying engine nacelles. Although improvements over the Ju 88A were modest, the RLM supported prototype development and briefly considered equipping the aircraft with the canceled BMW 139 radial engine before ultimately prioritizing the more powerful BMW 801.
Prototypes, Ju 88 B-0
The initial prototype Ju 88B V1, registered D-AUVS, conducted its maiden flight in early 1940 powered by 801A/B engines. While retaining fuselage and tail elements from the Ju 88 A-1, its greater engine power () enabled heavier payloads than could be accommodated by its relatively small bomb bay. To address this limitation, external wing-mounted racks were added beyond each engine nacelle, though this arrangement negatively impacted aerodynamic efficiency.
By summer 1940, a pre-production series of ten Ju 88 B-0 units based on Ju 88 A-4 airframes was delivered. The A-4 variant featured extended wings with rounded tips designed to enhance high-altitude performance compared to the shorter span of the earlier Ju 88A-1. Aerodynamic refinements included streamlined and pointed wing tips reminiscent of late-model British Supermarine Spitfire designs to maintain drag levels. Modifications to the airframe shifted its center of gravity, prompting installation of an elongated glazed cockpit that improved crew visibility and aircraft balance.
Operational testing yielded positive feedback from pilots regarding the updated cockpit layout. Nonetheless, the RLM questioned whether these incremental performance improvements warranted further investment. Consequently, pre-production aircraft were converted into long-range reconnaissance platforms by removing armaments and installing additional fuel tanks within the bomb bay.
Several airframes remained under Junkers’ control for further experimentation; one was outfitted with upgraded 801L engines and equipped with a small power-operated turret mounted atop the cockpit housing an MG 131 machine gun.
Variants
By 1942, setbacks in Junkers' candidate for the Bomber B program, the Ju 288, combined with advancements in RAF and Soviet Air Force fighter aircraft, created pressure to enhance the Ju 88. The RLM endorsed gradual performance improvements for the Ju 88B and commissioned Junkers to create an upgraded version: the Ju 188.
The only Ju 88 E-0 was outfitted with extra weaponry, including a rear-firing MG 131 mounted beneath the turret, a forward-firing MG 131 installed in the nose, and twin MG 81Z machine guns in the ventral Bola gondola firing backward. Two airframes were stripped of engines and wings for water ditching trials, anticipating extended overwater missions targeting British shipping. Another test aircraft (Ju 188 V1), converted from a Ju 88 A-4, featured an enlarged trapezoidal vertical stabilizer to enhance directional stability at high altitudes—a design later adopted on Ju 88G night fighters. This particular airframe was designated Ju 188 V1 to imply it represented a new model.
In October 1942, authorization was granted to commence Ju 188 production. A second prototype delivered in January repositioned the outer bomb racks nearer to the engines and initiated dive-bombing system evaluations in February. The RLM demanded compatibility with both BMW 801 and Jumo 213 engines through modular Kraftei ("power egg") setups to allow swift engine swaps. Although Jumo 213 deliveries were delayed, its superior high-altitude performance justified waiting. The second Ju 188 prototype underwent trials at Rechlin-Lärz Airfield from September to November 1943.
Ju 188 A & E
The Ju 188 was engineered to accept either Jumo 213A or BMW 801 G-2 powerplants without modifying the airframe, aside from redesigned annular radiators on Jumo-powered A-series variants to satisfy the cooling requirements of the Jumo 213. Initially both were designated as A models but were later renamed: the Ju 188A featured the Jumo 213 engine, while the Ju 188E was powered by the BMW 801.
The first three production Ju 188 E-1 aircraft equipped with BMW engines were delivered in February 1943, followed by further batches in March and April. After completing testing, they entered operational service, with their inaugural mission targeting a factory in Lincoln, Lincolnshire on 18 August 1943. By the end of that year, a total of 283 Ju 188s (including Ju 188Fs) had been produced across two new manufacturing facilities. Most frontline units replaced the MG 131 with MG 151/20 cannons in both nose and dorsal turrets. The Ju 188 E-2 variant served as a torpedo bomber and was essentially identical to the Ju 188 A-3.
Although deliveries of both A and E models were intended to proceed concurrently, delays with Jumo engines meant that the first Jumo-powered Ju 188 A-1 arrived shortly after the BMW versions but at a slower pace. By late 1943, an upgrade incorporating MW 50 methanol-water injection increased takeoff power for the Jumo engine, leading to deliveries of the Ju 188 A-2 beginning in early 1944.
A naval strike variant fitted with low-UHF-band FuG 200 Hohentwiel sea-search radar and torpedo racks was designated as Ju 188 E-2 (BMW) and Ju 188 A-3 (Jumo), differing mainly through removal of outer wing bomb racks. Despite these enhancements, performance improvements over the Ju 88 were modest: bombload capacity and bay dimensions remained unchanged; external ordnance reduced speed; maximum velocity was approximately . The dorsal turret retained a single gun but kept an adjacent single-gun flexible position; plans for tail armament were abandoned.
Ongoing supply difficulties with Jumo 213 engines resulted in significant production only of the E series powered by BMW engines. Due to limited availability, these aircraft were primarily assigned to Ju 88 units for specialized missions requiring extended range or enhanced performance. Roughly 500 Ju 188 A and E models were constructed before production ceased in mid-1944.
Ju 188 C
The Ju 188 C was conceived as the successor to the A and E variants, deliberately bypassing a "B model" to prevent confusion with the Ju 88 B. Only a single unit was produced by converting an A-1 airframe, outfitted with a novel FA 15 tail turret that was powered and remotely controlled, armed with two MG 131 machine guns aimed through a dual-periscope targeting system. Although this setup promised to strengthen defensive capabilities—a common shortcoming in German aircraft—the system’s unreliability ultimately led to its discontinuation.
Ju 188 D & F
By early 1944, development emphasis shifted toward reconnaissance adaptations of the A and E versions. These modifications involved removing the bomb aimer’s position and forward gun, while incorporating additional fuel tanks to extend operational range. The Ju 188 D-1 closely resembled the A-1 model, whereas the Ju 188 D-2 included nose-mounted radar tailored for maritime reconnaissance missions. Comparable conversions applied to the E series were designated as Ju 188 F-1 and Ju 188 F-2 respectively.
Ju 188 G & H
A major drawback shared by both the Ju 88 and Ju 188 was their limited internal bomb bay capacity, which necessitated carrying most ordnance on external underwing racks that degraded overall performance. The G and H variants sought to address this by adding a wooden pannier beneath the fuselage, thereby increasing internal bomb storage and creating space at the rear for a manned turret intended to replace the remote-controlled turret of the C model. However, this turret proved cramped and unsafe, leading the Reich Air Ministry (RLM) to reject it in favor of reintroducing the unreliable FA 15 system. Despite this, the designs retained the Bola ventral gondola for a rear gunner—a feature unnecessary in this context and detrimental to aerodynamic efficiency. With Jumo 213 engines prioritized for fighter production, the Ju 188 G-2 was equipped solely with BMW 801 radial engines; its reconnaissance counterpart was designated as the Ju 188 H-2. Neither variant reached production before the war ended; the G model remained at prototype stage. Notably, tail sections from Ju 188 G prototypes were later adapted for use on early Ju 287 jet prototypes.
Ju 188 R
During summer 1944, three E models were converted into night fighter configurations fitted with radar and armed with either four 20 mm MG 151/20 cannons or two 30 mm MK 103 cannons mounted in the nose. Although visibility improved compared to previous models, increased drag from radar equipment offset any speed gains, resulting in no production orders for the Ju 188 R-0.
High-altitude versions
In 1943, plans emerged to enhance all Ju 188 variants with enlarged wingspans and pressurized cockpits optimized for high-altitude missions. A single base airframe was proposed in three specialized forms: heavy fighter (Ju 188J), bomber (Ju 188K), and reconnaissance (Ju 188L). Mirroring the streamlined design of the Ju 88S, these late-stage models eliminated the Bola ventral gondola to achieve a sleeker nose profile. Both bomber and reconnaissance versions carried payloads within an elongated pannier beneath the central fuselage rather than utilizing the deeper fuselage extensions seen on earlier G and H types.
Stripped-down variants without defensive weaponry but featuring extended wings were developed as the Ju 188S fighter and Ju 188T intruder models. Powered by Jumo 213E-1 engines producing at takeoff and at altitude, the Ju 188T achieved speeds up to . At operational ceiling, the Ju 188S was capable of carrying only of bombs.
Prior to entering production, this series was redesignated as the Ju 388, reflecting its markedly improved performance and new RLM airframe designation.
Operators
- French Air Force (postwar period)
- Aviation Navale utilized several captured Ju 188 aircraft after the war
- Royal Air Force operated a minimum of two seized Ju 188s postwar, including models A-2 and A-3 (Werk Nr 190335 from 9./KG 26). The A-3 was surrendered following a landing at Fraserburgh on 2 May 1945.
References
- Dressel, Joachim and Manfred Griehl. Bombers of the Luftwaffe. London: DAG Publications, 1994. .
- "The Fortuitous 'Avenger'......Junkers' One Eighty-Eight". Air International. April 1982, Vol 22 No 4. Bromley, UK: Fine Scroll. . pp. 179–187.
External links
- "Ju-88's Successor." Popular Science, March 1944, p. 79. Cutaway illustration of the Ju-188.