A Failed Modernisation

In Chapter III we covered the history of the three main bomber types with which the Luftwaffe entered the war: The Heinkel He 111, Dornier Do 17, and Junkers Ju 88. The German staff did know before the war that these types would have to be replaced soon, especially the Do 17 and He 111. Unfortunately for them, the development of new bombers would largely fail.

A relatively successful project was started early in 1938 when a new specification was issued for a twin-engined bomber and reconnaissance aircraft. In June Dornier proposed to meet the demand with a new bomber, broadly based on the Do 17M, but substantially redesigned. This would not be an updated Do 17, but a new aircraft, with a larger and stronger fuselage and a longer wing span. The structural design was influenced by a requirement for maritime operations, and the resulting capabilities for bombing in dives up to 55 degrees and carrying torpedoes or sea mines. (A floatplane version was considered as well.) All this added weight and the new Do 217 was heavier than the Do 17M by several tons. The first prototype flew in October 1938 with DB 601 engines, and the third with Jumo 211 engines, but neither was adequate for the big Do 217. Versions with the BMW 801 radial or the new DB 603 in-line engine held more promise. A handful of Do 217A-0 series aircraft with DB 601 engines were completed as reconnaissance aircraft, but the version selected for production as a bomber was the Do 217E-1 with 1560 hp BMW 801 radials. The first of these aircraft were flown in October 1940, and they reached combat units in the spring of 1941. The new Do 217E were compact, somewhat ungainly aircraft. They had pleasant flying characteristics and handled very well as level bombers. The type’s performance as a dive bomber was inferior to that of the Ju 88, and Dornier began to experiment with dive brakes under the wings to replace the original cruciform dive brake installed in the extreme tail.

The performance of the Do 217 looked so good that the Luftwaffe also ordered the type into production as a heavy night fighter, the radar-equipped Do 217J. A new nose provided a powerful forward-firing armament of four MG 151/20 cannon and four MG 17 machine guns. However, as these aircraft retained their bombing equipment in addition to radar and forward-firing guns, crews soon complained about the Do 217J’s performance. It entered service in March 1942, but a decision to stop production followed in May. (On paper, at least, the Do 217J was a useful type for intruder operations, striking against British bomber bases at night.) Dornier still developed the Do 217N with DB603A engines, which was produced as 210 aircraft between the end of 1942 and September 1943, bringing the total production run of Do 217 nightfighters to 364, small enough to make it a wasted effort. Worse, the DB603 was at this time sufficiently troublesome that the operational usefulness of the Do 217N was somewhere between severely limited and non-existent.

The bomber version was further developed into the Do 217K and Do 217M, which both featured a new cockpit. This eliminated the ‘step’ between the pilot’s windscreen and the glazed nose in favour of a smooth bulbous nose contour, reminiscent of the He 177. The Do 271K-1 of early 1943 was powered by 1560 hp BMW 801L radials and had a creditable speed of 520 km/h at 5200 m. The K-2 was given longer span wings, and the Do 217K-2 and K-3 were developed for naval operations carrying guided bombs, respectively the Fritz-X guided bomb and Hs 293 guided missile. But production of the K series was curtailed by a shortage of the BMW 801 engine, and from the middle of 1943 the standard bomber was to be built as the Do 217M-1 with the DB 603A-1. The Do 217M was perceived to be a stop-gap bomber, but in the autumn of 1943 it became obvious that the DB 603 was neither reliable enough nor available in sufficient quantity to make it feasible to deploy the Do 217M in significant numbers. Production of the type was duly halted, though some would serve until the end of the war.

The career of the Do 217 was seriously curtailed by the lack of sufficiently powerful and reliable engines, but other bomber designs would fare even worse.

In the late 1930s, as 1000 hp aircraft engines were entering service, there was an expectation that 2000 hp engines were just around the corner, and a temptation to design new aircraft around them. This was by no means an exclusively German illusion. The USA started to struggle with big engine designs such as the Pratt & Whitney H-2600, Lycoming H-2470, Wright R-2160, and Chrysler IV-2220 before, late in the war, the big Wright R-3350 radial entered service with mixed results. In Britain high hopes were expressed for the Rolls-Royce Vulture, Napier Sabre, and Bristol Centaurus; the first would painfully fail and the latter two would enter service with much delay. German engine development, besides the DB603 and Jumo 213, envisaged engines such as the 18-cylinder BMW 802, the 28-cylinder BMW 803, the 24-cylinder DB604, and the 24-cylinder Jumo 222.

The Jumo 222, with six banks of four cylinders in a radial pattern and liquid cooling, appeared to be the most promising of the future engines. It was running on the bench in 1939, but development of this engine encountered difficulties that were no doubt enhanced by the wartime lack of the materials required to create high-strength steel alloys. When approval for series production was finally given in the middle of 1942, it was expected to enter production in the autumn of 1944. The Jumo 222A/B was then expected to deliver 2300 hp, with the 3000 hp Jumo 222C/D being expected in the autumn of 1945. The obvious problem was that the “Bomber B” specification for a new fast medium bomber, designed around such engines, had been issued in July 1939! By 1944 the arrival of jet engines and the growing potential of the V-12 engines made the Jumo 222 largely superfluous and it never entered full service. (Its development nevertheless continued.)

That 1939 “Bomber B” program for a new medium bomber (the “Bomber A” being the heavy bomber) was certainly ambitious, as it sought a fast, three-seat high-altitude bomber with a pressure cabin and defensive armament in remote-controlled gun turrets. The specification called for an aircraft packed with modern technology, a maximum speed of 600 km/h at 7000 m, a range of 3600 km, and a bomb load of 2000 kg. The engines envisaged where the Jumo 222 or the DB 604. The closest equivalent elsewhere was probably the North American XB-28, a beautiful aircraft powered by two turbo-supercharged R-2800 radials. The B-28 project was initiated in November 1939 and the first prototype flew in 1942. Significantly, the B-28 would not enter production as the USAAF concluded that the medium bombers that it had (the A-20, B-25, B-26 and the new A-26) met its wartime needs, but it was considered a technical success. With a loaded weight of 17,250 kg, the XB-28 benefited from the famous Pratt & Whitney R-2800 engine, a rugged and reliable radial that delivered 2000 hp. The closest German equivalent to the R-2800 was BMW 801, but although the BMW 801 was a successful engine that set new standards for streamlined installation and ergonomic engine control, it wasn’t as powerful.

The RLM sent out the request for proposals to Junkers, Focke-Wulf, Dornier, Henschel, and Arado. (Incidentally, most German aviation firms were named after their founders, but Arado was not. It owed it existence to the industrialist Hugo Stinnes, and its name, Spanish for plough, was apparently given by Walter Hormel and Felix Wagenführ.) Arado’s unconventional twin-tail E 340 design was never built, but the Fw 191, Do 317, and Ju 288 made it into metal. The Ju 288 promised to make fast progress because Junkers had already done a fair amount of work on its design, as project EF73. Apparently undeterred by the production problems and delays encountered with the Ju 88, Junkers indicated that it would be able to start delivering the Ju 288 in January 1942, and industrial plans were prepared to build 300 per month! Even after the problems with the Jumo 222 became apparent, Junkers’ representatives foolishly promised that production could start by June 1942, if necessary with other engines.

The Ju 288 V1 prototype flew in January 1941, with BMW 801 engines as the Jumo 222 was not ready. (The Ju 288 V5 would fly with the Jumo 222 in October.) The aircraft featured a long and slender fuselage of nearly-rectangular cross-section, a bulbous cockpit with all-around glazing, twin tail fins, and dive brakes under the outer wing panels. A series of prototypes were built representing the three-seat Ju 288A, the Ju 288B with the crew increased to four, and the Ju 288C redesigned around the DB 606. The latter, in effect a pair of DB 601 engines joined side-by-side to a single reduction gear, was the only viable alternative to the Jumo 222, but it was substantially bigger and heavier. (It also meant that the Ju 288C was to have the same engines as the He 177A heavy bomber.) The Ju 288 program finally ground to a halt in June 1943. No less than twenty-two prototypes were completed, of which seventeen were lost in accidents. The Ju 288C, as represented by the V103 prototype, would have had a crew of four, gun turrets under the nose, in the tail and under the belly, a wing span of 22.66 m and a loaded weight of 21,800 kg. Whatever promise it held was irrelevant by mid-1943, as Germany could no longer afford to put it into production, even if it had the engines.

Focke-Wulf’s competing Fw 191 design suffered a similar fate, but besides struggling with the unavailability of the planned engines, development was affected by a heavy reliance on electric instead of hydraulic systems on the first prototype. The very successful Fw 190 fighter had introduced a number of electric systems, but on the Fw 191 they proved to be a source of major problems. Though the Fw 191 V1 was flown early 1942, it was only in the spring of 1943 that the V6 flew with the troublesome electrics replaced with hydraulics and Jumo 222 engines. Soon thereafter, the Bomber B program was abandoned. The sleek Fw 191 would be a major influence on the design of the Ta 154 twin-engined fighter.

Dornier’s Do 317 was perhaps the least ambitious, as it was essentially an enlarged development of the Do 217 described above. It had a larger bomb bay than the Do 217, a pressure cabin, and armament in remote-controlled turrets. A fairly chunky design in its initial form, it would have been given a longer-span wing if it had entered production. But the Do 317 V1 did not fly until 8 September 1943, powered by DB 603 engines. By this time the programme had already been abandoned. German requirements were shifting away from the complex Bomber B towards a simpler high-speed bomber requirement, which would be met by the selection of the Do 335. It is noteworthy that early in the war, the RAF expected attacks by German high-altitude bombers, which prompted the development of Spitfire variants with a pressure cabin, as well as the highly specialised Westland Welkin interceptor. But relatively few Spitfires Mk.VII would be built, and the Welkin was never issued to a squadron, as the threat did not materialise.

By May 1942 the RLM understood that it was in a difficult position. The old bombers were ageing and the new ones were delayed. Reluctantly, it considered the options for an interim bomber. The best available solution was offered by Junkers, who had continued development of the Ju 88 as back-up scenario. By October 1942 the this option was picked up to create the Ju 188, a derivative of the Ju 88 that incorporated features from the Ju 88B and Ju 88E designs and the Ju 88G nightfighter. The new bomber would lack advanced features such as remote-controlled gun turrets, and have a modest bomb load, but thanks to improved aerodynamics and 1750 hp Jumo 213A-1 (on the Ju 188A) or 1700 hp BMW 801D-2 or G-2 engines (on the Ju 188E), it was faster than the Ju 88A. Externally, it was distinguished by longer-span wings with pointed tips, squared-off tail surfaces, and a smoother cockpit that incorporated a lightweight turret mount for a MG 131 or MG 151/20. It also had a MG 151/20 in the nose, a MG 81Z in a ventral position, and a dorsal MG 131. (Both unmanned and manned tail turrets were developed, but neither was practical.) It was clearly a warmed-up Ju 88 and most Ju 188s were distributed to existing Ju 88 units. They were well-liked aircraft, but production only ran to about 1000 Ju 188s until June 1944, when the worsening war situation shifted production to fighters.

The Ju 88 story still didn’t end there, as in September 1943 the so-called Hubertus Programm called for a fast high-altitude bomber. On an airframe that was based on the robust and reliable Ju 188, this reintroduced some of the technology of the Ju 288: High-altitude engines, a pressure cabin, and a remotely-controlled FHL 131Z tail turret made a new appearance. The engines were to be the turbo-supercharged BMW 801TJ, the Jumo 213E-1, or on some projected models, again the Jumo 222! The program continued the multi-role tradition of the Ju 88 by planning the Ju 388K bomber, Ju 388L reconnaissance aircraft, Ju 388J nightfighter, and Ju 388M torpedo-bomber.

Production models of the Ju 388 were powered by versions of the BMW 801 radial and never added up to a significant total. It saw most service as the Ju 388L reconnaissance aircraft, of which 47 were completed, while 15 Ju 388K bombers and maybe three Ju 388J fighters were built until the program was canceled early in 1945. Disappointing performance may have contributed to this decision. And while the Ju 388 was at least on paper a useful high-altitude reconnaissance platform, it was arguably superfluous when the Luftwaffe was receiving the jet-powered Ar 234, even though this too was only available in small numbers.

There have been many what-if and fantasy scenarios based on aircraft that the Third Reich could not have built or supported, such as large fleets of four-engined bombers or fanciful jet fighter and bomber designs. In contrast, a modern twin-engined medium bomber was within practical reach. The Luftwaffe needed such aircraft, and if engine and airframe development had been managed better, it could have received them in significant numbers. They would not have changed the outcome of the war, because after December 1941 (at the latest) the Axis cause was lost. But in the German reality, a modern medium bomber would have been very useful on the Eastern Front to support the army by interdicting Soviet supply lines; it would have been valuable in the Mediterranean and the Atlantic coast for anti-shipping operations; and it could have been used against airfields and ports in the UK to disrupt bomber operations and the assembly of the D-Day invasion force.

But the combination of over-ambitious goals, the scattering of effort over too many projects and variants, the dependency on unavailable engines, and industrial mismanagement cost the Luftwaffe dearly. The increasingly obsolescent equipment of the Kampfgruppen made them ineffective in a context of growing enemy air superiority, and this allowed the Allies to build up their forces for offensives largely unhindered by bombing attacks, and often unseen by reconnaissance. Criticism of the Luftwaffe’s bomber policy has usually overlooked the consequences of its failure to modernise its medium bomber force.

Chapter VIII: American Mediums