Introduction
The usual epithet applied to the German Air Force (Luftwaffe) is one of defeat as in the first six months of 1944 the Luftwaffe fighter defences were shot out of the skies over the Reich by American long-range fighters. By the time of the Normandy invasion, the Luftwaffe was unable to mount anything other than a token response to Allied air forces which had achieved air supremacy. The underlying causes for this situation were the insufficient numbers of planes, low levels of pilot training and outdated aircraft. The factors behind these causes were long standing and went right back to the formation of the Luftwaffe in 1933 and will be the subject of this essay.
The studies by Allied intelligence,[1] in the immediate post war period correctly identified the principal causes of Luftwaffe defeat and the factors behind them. However the United States Strategic Bombing Survey[2] (USSBS) researchers including John Kenneth Galbraith, a leading American economist, were led astray by the views of the USSBS translator, Dr Rolf Wagenführ, a Reich economist and statistician.[3] They produced two ideas that later proved to be incorrect, the idea of a Blitzkrieg war and of Albert Speer’s economic miracle.[4] These views were given further weight in 1965 by the English economist, Alan Milward.[5] This paradigm was challenged in the early 1980s by the work of Horst Boog,[6] Williamson Murray,[7] and Richard Overy who stressed the limitations in capacity and efficiency of the German aircraft industry and dismissed the Blitzkrieg view of the Luftwaffe. They saw the Luftwaffe as a general-purpose air force, planning for strategic bombing, focussed on air superiority and with only a limited element given over to Army support. In turn this economic view was modified by the work of Adam Tooze,[8] who saw balance of payments issues as the main constraint on the German economy, especially during rearmament. This limited the supply of raw materials and meant that Germany had to pursue a sequential mobilisation, firstly the Army (Heer) to fight Poland, France and Russia and secondly the Luftwaffe and Navy (Kreigsmarine) to fight Britain and America. Finally in 2015, Phillips O’Brien[9] advanced the view that the Western Allies created an air-sea super battlefield that stressed the Luftwaffe at both front and rear, which caused its collapse of effectiveness and defeat in 1944.
This essay will concentrate on the underlying structural causes in the decline of the Luftwaffe which arose from its creation during the 1930s. The way it was formed produced an air force large in numbers, yet weak in resilience that was incapable of conducting campaigns of extended duration, such as the Battle of Britain or the invasion of the Soviet Union. Recognising that the need to fight on three fronts and in defence of the Reich against a more numerous enemy was the immediate cause of defeat, nonetheless the underlying causes created this situation and so are the main focus of this study.
Which raises the question of how to measure effectiveness, and this essay has addressed the issue by adopting Overy’s ‘five major factors that conditioned the evolution and use of air forces.’ as a framework for discussion.[10] The other factor is the definition of German air power, which in this case is deemed to be both aircraft and ground air defences.
Crashed Luftwaffe night fighter 1945
Strategic conception
The Luftwaffe was part of von Seckt’s effort to circumvent the restrictions of the Treat of Versailles during the 1920s.[11] This effort was led by General Staff officers who first created the idea of a ‘risk Luftwaffe’ as a corollary to Tirpitz’s ‘risk fleet’ of the 1890’s[12] and then in 1935 moved onto the doctrine of Colonel Wever of the Luftkommandoamt, expressed in L.Dv. 16 Luftkriegführung [Air warfare leadership]. The doctrine’s general concept matched that of the Heer, in that it envisaged a rapid, short ranged strike on one of Germany’s neighbours, using a rapid mobilisation, followed by a decisive battle close to the frontier to destroy their military forces, which would lead to imposing German will on the enemy country. The Luftwaffe doctrine saw three main tasks: firstly a pre-emptive strike to destroy the enemy air force to achieve air superiority at the opening of the campaign, secondly direct support of the Heer and Kriegsmarine, and finally war against the sources of strength of the enemy such as ports and railways.[13]
This doctrine cemented the operations staff officer (Ia) in the leading role, both in command and in management of the Luftwaffe. This domination was inappropriate for a technical and economic military service where intelligence, signals, supply, development and production were of key importance and it downplayed the role of the Flak and air transport arms in air power. This led to serious shortcomings, for example the Chief of the General Staff did not know the operational status of air units, which led to overestimation of the number of aircraft on missions.[14]
Operations staff officers (Ia) with no engineering background were appointed to technical posts over the heads of older, experienced engineers, there was a lack of promotion of engineers and many were left in menial roles. In turn this created problems with industry and the Luftwaffe testing centre at Rechlin, both with the design of aircraft aerial weapons and series production of operational models. There was little understanding of the time needed to develop a new airframe (three to four years,) or engine (four to five years,) and no understanding of serial production, so that aircraft programmes were delayed by numerous requests from the field. For instance, the key Ju-88 programme was delayed by 15,000 changes during development.
Perhaps the most serious failure resulting from the domination of the Ia officer, was in the field of training. In 1938, the squadrons (staffels) were at full strength, although this only allowed for one crew per aircraft and the training organisation was only large enough to cover either an expected loss rate of 25-30% or the expansion of the number of aircraft, but not both.[15] By May 1940 the Luftwaffe had 5,446 first line aircraft of which 4,020 were operational.[16] Yet a year later in June 1941, the number of first line aircraft was only 5,599 and the Luftwaffe was able to concentrate 3,032 against the Soviet Union, as it had to supply 282 for Reich Air Defence, 423 for the Mediterranean, 861 against Britain and 200 for Norway.[17] Personnel losses in the first year of the war (September 1939 to August 1940) had been 12,813.[18] In the following nine months, a further 5,899 were lost at the front with an additional 2,222 lost at home. Things would continue to deteriorate with the invasion of the Soviet Union, which by December 1941 had cost a further 20,221 casualties, exceeding the annual rate of replacement by a wide margin.
In the winter of 1941, the Soviet counter offensive surrounded German troops in large pockets at Demyansk and Kholm, which had to be resupplied by air. Yet the Luftwaffe did not possess a transport service, except for the small 8 Fliegerkorps attached to the paratroop forces and, instead Ju-52 transport aircraft had to be taken from the ‘C’ and blind flying schools. There were heavy losses of both planes and aircrew. This happened the following year during the Stalingrad encirclement and in Tunisia both of which seriously affected the training of bomber crews and the night flight programme. Expansion of aircrew training was achieved rising from 5,299 in 1942 to 12,164 in 1943 yet only at the expense of reducing the number of flight hours, a factor compounded by fuel shortages later in the war. The combination of these factors led to a large rise in training accidents with higher losses of aircraft and aircrew and, a lowering of the competence of German pilots compared to Allied ones, which in turn led to higher combat losses.[19]
This strain on training has to be taken in context with the wider decline of the strategic situation after June 1941, coupled with an increase in the number of roles taken on by the Luftwaffe that made the training problems fatal. While the campaign in Russia dragged on into 1942 and 1943, the Soviet Air Forces (VVS) recovered and began to pose a significant opposition to the Luftwaffe, using strategic reserves to concentrate forces at important battlefields, and grouping experience pilots into specific squadrons. Using these methods the VVS began to wrest air superiority from the Luftwaffe, particularly after the key Kuban bridgehead battle in early 1943.[20] At the same time, the British and American forces in the Mediterranean grew in strength and capability leading to serious Luftwaffe losses in defence of Tunisia and Sicily in 1943.
Meanwhile the growth of the British bombing campaign of the Reich in 1942 grew to be a major threat that drew fighter staffels back to Germany, and when combined with the first 1943 US daylight campaign, forced a change in production priority from bombers to fighters.[21] Adding to the Luftwaffe’s woes were demands for it to take on other roles. It had to convert bomber staffel to send to the Arctic as torpedo bombers against Allied convoys to Russia, heavy fighters had to be converted to night fighters to protect the Reich and in Russia it had to fly constant ground support missions to make up for shortages of artillery, missions that suffered heavy losses in aircraft and crew. In an attempt to deal with these increasing demands for specialised and dedicated aircraft, the Luftwaffe evolved its organisation moving from geographically based Luftflotte to one more based on mission type, yet the gains in efficiency were relatively small, when compared to the leap in training losses in 1943.
Heinkel factory with He-115 floatplane in foreground and He-111 bombers in distance
Economic Capability
The prevailing view of the German aero industry by the time of the 1926 Paris Air Agreement was that ‘Germany already possessed an efficient aircraft industry which had kept pace with current technical developments in the rest of the world. She was also maintaining a rate of production as high as that of any other European country.’[22] Despite Germany’s promising initial industrial base, her early lead in rearmament, state control of leading aero manufacturers such as Junkers, and generous funding from ‘Mefo’ bills, nonetheless by 1941 she had fallen behind. That year the UK would produce 13,200 combat aircraft, the USSR 8,200 and Germany just 8,400.[23] Germany had out produced the UK in 1939, yet in 1940 she had fallen behind and would not recover the lead until 1944, by which time she lacked the pilots and fuel to make use of this. How could this have happened?
It has long been known that the German economy invested heavily in rearmament in the second half of the 1930s and that to a large extent that rearmament drive had failed to deliver the weapons required by 1939 or even by 1942. Overy suggests that this was due to a ‘general unwillingness of much of German industry to co-operate in preparing for total war,’[24] and that many of the long term investment projects had failed to reach maturity by the start of the war. This explains the phenomenon of Germany spending an estimated $6 billion on rearmament by 1940, while Britain spent only $3.5 billion and yet produced 50% more aircraft, and almost as many tanks.[25] Factories were built that failed to come into production, and too much of the working production was expensive, over-engineered, short runs designed to make profit rather than masses of weapons.
Tooze builds on this argument, by adding in the balance of payments problems facing Germany, as she had to import essential raw materials for rearmament, which had to be paid for by exporting finished goods, including military equipment. Conquests brought temporary relief, for instance in the form of captured Austrian gold reserves, yet generally the German economy could not be diverted fully towards rearmament as it was needed to generate export income. For instance on 14 October 1938 Goering announced a five-fold expansion of the Luftwaffe by 1942 with a fleet of 21,750 aircraft with 7,000 Ju-88 and 800 He-177 bombers. Yet only a month later, steel allocations had to be cut, due to balance of payments problems.[26] This need to overcome the resource constraint reached its apogee during the planning for the invasion of the Soviet Union:
“Here was the perverse logic of Barbarossa in a nutshell. The conquest of the oilfields of the Caucasus, 2,000km deep in the Soviet Union, was not treated as the awesome military-industrial undertaking that it was. It was inserted as a precondition into another gargantuan industrial plan designed to allow the Luftwaffe to fight an air war, not against the Soviet Union, but against the looming air fleets of Britain and the United States.[27]”
The constant shifting of priorities and scarce materials between programmes, the call up of workers and the need to disperse factories under air attack, all these changes needed months or even years to work through the system, so that production could be built up to speed.[28] For instance the change to fixed price contracts in the summer of 1938 and the reduction of the number of aircraft types built, coupled with longer production runs, demonstrated steady improvements in aero industry productivity over several years before 1942.[29]
Me262 squadron
Scientific and technical mobilisation
The reality of the interwar period was that technological advancement in design of airframes and aero engines was driven by military orders and not civil aviation.[30] European civil aviation was a small, subsidised and luxury service, often surviving only due to government mail contracts, while private aviators represented an even smaller share of the market. The British were world leaders in both airframe and particularly engine production, with Rolls Royce making inline engines and Bristol rotary engines.[31] The Bristol Jupiter engine was licensed in 14 countries including France, Germany, Japan and USSR.
While Germany had innovative firms such as Junkers, nonetheless in 1932 the aero industry was small with just eight aircraft and five engine factories[32] numbering just 3,000 workers,[33] while the five largest British firms in 1935 (before rearmament,) employed 22,000 workers (66% of British aircraft employment).[34] The German aero engine industry was less well developed and power plants were a source of constant problems for designers.[35] Similarly the German electronics industry was around one tenth the size of Britain’s and while occupied countries would soon provide access to the Dutch company, Phillips and French Thomson, there was still a deficit.[36] With such a small, initial industrial base in 1933 compared to Britain, Germany would struggle to expand both production and new aircraft designs in an economically efficient manner.
German aircraft designs are recognised to have been workmanlike, yet some underperformed.[37] The usual narrative is that at the foundation of the Luftwaffe, it’s first-generation aircraft such as the He-51 fighter were inferior to contemporary designs, while the second generation aircraft produced during the period of Erhard Milch, such as Bf-109, Bf-110 and He-111were the equal of contemporaries. However Milch was sidelined after 1935 due a scandal surrounding his Jewish father and his role taken by Ernst Udet whose third generation designs for the Ju-88, Me-210 and He-177 were brought into production before they were mature operational aircraft. After his return in 1940, Milch faced with this gap, concentrated on mass producing proven designs and leaping forward a generation to jet and rocket aircraft. This was a high risk strategy to overcome the technical challenges, nonetheless it produced a number of successful operational design in the Me-262 jet aircraft and the Me-163 rocket plane. Yet the pressure of events meant that these designs were brought into service before being fully mature and so were beset by operational issues.
While this narrative covers the design history, it downplays the very real challenges faced by all air forces in grappling with the rapidly evolving technology of the period. For instance the RAF developed two fighters in response to Air Staff Requirement F.10/35, the Spitfire and Hurricane which underwent development right through to the end of the war, as did the Bf-109. Yet the RAF ran into many of the same problems of making the next leap forward in capability to a 2,000 hp engined aircraft. The F.18/37 Typhoon came into service in 1941 but offered no improvement in high altitude capability over existing marks of Spitfires, until the improved Tempest entered service in 1944, seven years after the Staff Requirement was issued.38 Similarly the three designs of heavy bomber produced to B.12/36 did not enter service until 1941-2, some six years later, even give the highest priority. Likewise the He-177 started life in 1937, yet never gained sufficient priority before 1940, as it was felt that the Ju-88 could meet most of the requirements, and after 1942 it was not possible to assemble sufficient resources to overcome the design flaws and start mass production and operation.[39] In the end Germany only produced 1,169 He-177 and never got past the prototype stage with its replacement four-engined replacements.
In spite of this the Luftwaffe successfully built an integrated air defence system covering much of western Europe, combining electronic detection, with fixed defences gun defences. mobile day and night fighters and much of the civil defence service. Flak posed a real threat to Allied bombing aircraft throughout the war, forcing their aircraft to fly at high altitude and avoiding major targets, which reduced bomb loads and endurance. The gun technology was easy to produce and the crews were provided by men unfit to be soldiers, teenagers and POWs while large parts of the control rooms were run by women. Yet by 1942 increasing aircraft speeds and altitudes brought antiaircraft gun technology to the limits of technical capability and required a leap forward to guided missiles.[40]
Ju-88
Political and social reception
The Luftwaffe was closely integrated into an overall war effort, providing support to the other branches of the military to achieve a combined military objective. Much of its early success was due to a well thought out plan of operations, albeit in the limited scope of achieving air superiority in a short military campaign. It started to struggle once it was asked to conduct operations outside the narrow confines of this original remit, such as the bombing campaign against Britain or the attritional campaign in Russia, for which it was neither structured nor equipped. Nonetheless as a generalpurpose air force, the Luftwaffe proved adaptable to changing circumstances, providing long range maritime patrol aircraft, short range anti-shipping and ground attack staffels.
Much of this was due to a capable and competent officer corps. At the top Hermann Goëring, was the number two man in the Reich, leader of the Four-Year Plan and commander-in-chief of the Luftwaffe. He provided political support and his position in the Four-Year Pan gained his service in excess of 40% of German weapons production41 and its own place in the economic hierarchy outside the other military services, a position that was only reversed by Albert Speer in 1944. Germany had very limited manpower reserves and yet the Luftwaffe grew to 3,000,000 personnel (1,500,000 soldiers, 600,00 Flak troops, 600,000 civilians and 400,00 auxiliaries such as schoolboys, Volksturm and Hiwis,) by November 1943.[42]
While Goëring took the traditional figurehead role of a Prussian general, the day to day running of the Luftwaffe was left in the hands of State Secretary Erhard Milch for production and development and the Chief of the Air Staff for operations. The relationship between the older technical engineers around Milch, and the younger officers of the Staff, with their Heer General Staff backgrounds, was poor resulting the resignation of Kesselring as Chief of Staff in 1938 and a lack of coordination both within and between the two section:
From the modifications in organisation and chain of command described above, it is apparent that the wartime, top-level organisational structure in effect at the beginning of the war was inadequate to meet the demands of effective military leadership, The overly simplified organisation of the General Staff, with the resultant diversion responsibility for important sectors of military activity, also proved to be unsatisfactory in the long run.[43]
This situation deteriorated further during the tenure of Ernst Udet between 1939 and 1941, who lacked Milch’s technical knowledge of design and production. In large part the problems of the introduction of new aircraft and the inefficiency of aircraft manufacture can be laid at the door of these personality clashes and the inadequate organisational structure of the Luftwaffe during the late 1930s and early war years.
Luftwaffe ground crew load a Ju-87 in Russia
Conclusion
The period of rearmament followed by the Second World War represented a unique period of rapid technological advance, as in 1935 the standard British fighter was the 600 hp Gloster Gauntlet fabric covered biplane, by 1939 the 1,000 hp Hawker Hurricane, by 1941 the 2,000 hp Hawker Typhoon and by 1944 the jet engined Gloster Meteor. All this happened within ten years, while the life of the Third Reich was just twelve years. This exponential advance in technology was accompanied by a similar rise in costs. Advances were becoming far more difficult to achieve, fewer new types of aeroplanes were produced and they were growing ever more expensive. Middle ranking European powers, could no longer afford to produce the full range of aeroplanes and the most expensive types such as inter-continental, multi-engine bombers were beyond their pockets. Only the United States possessed sufficient size and resources to fill all of the niche’s in the air power environment, and to build sufficient number of prototypes to ensure success in any particular class of aircraft.
Given this environment, Germany could easily build a large, advanced air force by 1939. With a continental commitment to a large land army, funding and building the leap from 1,000 hp engines to 2,000 hp engines and then onto jet engines, at the same time as building a heavy bomber fleet was always going to be challenging. By contrast, Britain was able to use her maritime position to concentrate her resources on air warfare and limit her army to 50 divisions, (at the time of the invasion of Russia the German Army had 180 divisions.)
Yet the Luftwaffe attempted this herculean task of rearmament, with serious structural and personnel issues that limited its productive capacity, wasted its design talent, led to poor decision making and wasted finance on a large scale. A focus on short term wars, led to poor decisions regarding training, replacement aircraft and aerial transport services. This produced a Luftwaffe that was large in numbers by contemporary standards, yet it lacked depth and the ability to sustain combat for more than a few months. The early campaigns fitted the Luftwaffe’s conception of warfare and posed few problems, however the extended campaigns against Britain and the USSR in 1941 soon exposed the weaknesses in organisation and the lack of depth in capability which led to fatal declines in aircrew, aircraft numbers and in replacements.
Despite every effort to recover from this position, the need to fight on three fronts robbed the Luftwaffe of any respite and the service declined in experienced pilots, modern aircraft and in aircraft numbers until they were finally overwhelmed in 1944. Yet it is easy to overstate this decline, as the Flak arm continued to effectively defend the Reich and the Heer right up to 1945.
He-177 Urals bomber
1 Air Ministry Intelligence Branch, The Rise and Fall of the German Air Force 1933-1945 (London: Arms and Armour Press, 1983).
2 ‘United States Strategic Bombing Survey: Summary Reports’, 1984, https://www.airuniversity.af.edu/AUPress/Display/Article/1541846/the-united-states-strategic-bombing-surveys/.
3 Mr. J. Selwyn, ‘Symposium of Interrogations and Reports on German Methods of Statistical Reporting’, 1946, p.13, https://www.cdvandt.org/bios-273.htm. Interrogation of Dr Rolf Wagenführ by British Intelligence Objective SubCommittee
4 Richard Overy, ‘An Economy Geared to War’, History Today 51, no. 11 (November 2001): 27, http://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=5859170&site=ehost-live. Overy argues that the original authors of the Blitzkrieg economy were Burton Klein (USSBS) and the British historian, A.J.P. Taylor
5 Alan Steele MILWARD, The German Economy at War. (London: Athlone Press, 1965).
6 Horst Boog, Die deutsche Luftwaffenführung 1935-1945: Führungsprobleme, Spitzengliederung, Generalstabsausbildung, Beiträge zur Militär- und Kriegsgeschichte ; Bd.21 (Stuttgart: Deutsche Verlags-Anstalt, 1982).
7 Williamson Murray, Air University (U.S.), and Airpower Research Institute, Strategy for Defeat: The Luftwaffe, 1933- 1945 (Maxwell Air Force Base, Ala.: Air University Press, 1983).
8 J. Adam Tooze, The Wages of Destruction: The Making and Breaking of the Nazi Economy (London: Penguin Books, 2007).
9 Phillips Payson O’Brien, How the War Was Won : Air-Sea Power and Allied Victory in World War II, Air-Sea Power and Allied Victory in World War II (Cambridge, United Kingdom : Cambridge University Press, 2015., 2015)
10 Horst Boog, ed., The Conduct of the Air War in The Second World War: An International Comparison : International Conference of Historians : Papers (New York; Oxford: Berg, 1992), 10–11, https://books.google.co.uk/books?id=d8N8AAAAIAAJ.
11 James S. Corum, ‘From Biplanes to Blitzkreig: The Development of German Air Doctrine Between the Wars’, War in History 3, no. 1 (1996): p.90, http://www.jstor.org/stable/26004494. 12 Wilhelm Deist et al., eds., Germany and the Second World War: Volume 1: The Build-up of German Aggression: 1, trans. P. S. Falla, Dean S. McMurry, and Ewald Osers (OUP Oxford, 2015), p.481.
13 Deist et al., p.494
14 Boog, Die deutsche Luftwaffenführung 1935-1945, pp.20.
15 Boog, p.27.
16 Klaus A. Maier et al., eds., Germany and the Second World War: Volume 2: Germany’s Initial Conquests in Europe, Germany and the Second World War (Oxford, New York: Oxford University Press, 2015), p.279.
17 Horst Boog et al., Germany and the Second World War: Volume 4: The Attack on the Soviet Union: The Attack on the Soviet Union Volume I, (Oxford : Oxford ; New York: Clarendon Press, 1998), p364-371.
18 Maier et al., Germany and the Second World War, p304. Killed, wounded and missing
19 Horst Boog, Gerhard Krebs, et al., Germany and the Second World War: Volume 7: The Strategic Air War in Europe and the War in the West and East Asia, 1943-1944/5, Germany and the Second World War (Oxford, New York: Oxford University Press, 2006), 162.
20 Richard Müller, The German Air War in Russia (Baltimore, Md.: Nautical & Aviation PubCoof America, 1993), pp.110- 112
21 O’Brien, How the War Was Won : Air-Sea Power and Allied Victory in World War II, pp.291.
22 Air Ministry Intelligence Branch, The Rise and Fall of the German Air Force 1933-1945, p.2.
23 Mark Harrison, ed., The Economics of World War II: Six Great Powers in International Comparison (Cambridge: Cambridge University Press, 1997), table 1.6
24 R. J. Overy, ‘Hitler’s War and the German Economy: A Reinterpretation’, Economic History Review 35, no. 2 (May 1982): 279, https://doi.org/10.2307/2595019.
25 Overy, 286.
26 Tooze, The Wages of Destruction, 288–93.
27 Ibid. p.452
28 Ibid. p.342.
29 Jochen Streb, Jonas Scherner, and Lutz Budrass, ‘Demystifying the German Armament Miracle During World War II: New Insights from the Annual Audits of German Aircraft Producers’, SSRN Scholarly Paper (Rochester, NY, 1 January 2005), 4, https://papers.ssrn.com/abstract=661102.
30 Sebastian Ritchie, Industry and Air Power: The Expansion of British Aircraft Production, 1935-41 (London: Frank Cass, 1997), 8–28; David Edgerton, England and the Aeroplane: Militarism, Modernity and Machines (London: Penguin, 2013), 59.
31 Ritchie, Industry and Air Power, 113.
32 Prof Richard Suchenwirth, The Development of the German Air Force 1919-1939, USAF Historical Studies 160 (USAF Historical Division, 1957), 119, https://www.afhra.af.mil/Information/Studies/Numbered-USAF-Historical-Studies151-200/.
33 Deist et al., Germany and the Second World War, 488
34 Ritchie, Industry and Air Power, 21.
35 R. J. Overy, ‘From “Uralbomber” to “Amerikabomber”: The Luftwaffe and Strategic Bombing’, Journal of Strategic Studies 1, no. 2 (1978): p.172, https://doi.org/10.1080/01402397808436996.
36 Boog, Krebs, et al., Germany and the Second World War, p.198.
37 A. D. Harvey, ‘German Aircraft Design during the Third Reich’, Air Power History 61, no. 2 (2014): 28–35, https://www.afhistory.org/air-power-history/2014-air-power-history-archive/
38 Colin Sinnott, The RAF and Aircraft Design: 1923-1939 : Air Staff Operational Requirements (London: Cass, 2001), pp.181-184.
39 Overy, ‘From “Uralbomber” to “Amerikabomber”’, pp.164-169.
40 Horst Boog, Werner Rahn, et al., Germany and the Second World War: Volume 6: The Global War (OUP Oxford, 2001), p.614; Boog, Krebs, et al., Germany and the Second World War, p.228
41 Rolf-Dieter Muller, Hans Umbreit, and Bernhard R. Kroener, Germany and the Second World War: Volume 5 Part 2: Organization and Mobilization of the German Sphere of Power : Wartime Administration, Economy, and Manpower Resources 1942-1945 (Clarendon Press, 1990), p.598 Table II.iv.2.
42 Boog, Krebs, et al., Germany and the Second World War, p.225
43 Gen-Lt Andreas Nielsen, The German Air Force General Staff, USAF Historical Studies 173 (USAF Historical Division, 1957), p.83, https://www.afhra.af.mil/Information/Studies/Numbered-USAF-Historical-Studies-151-200/
He-277 Amerika Bomber