Aviation of World War II
On the Eve of War
D.A. Sobolev, D.B. Khazanov
After the Nazis came to power in Germany, the USA and France became the main trade partners of the USSR where the aircraft industry was concerned. Several licenses were bought in these countries during the 1930s for the production of aviation engines. These were made in the USSR and designated M-25, M-85, and M-100. The US sold licenses for Douglas DC-3 (PS-84, or Li-2) passenger and cargo aircraft, the multipurpose Consolidated XPBY-1 (GST) flying boat, and the Vultee V-ll (BSh-1) ground-attack aircraft, which we put into series production.
But, it would be wrong to think that all ties with Germany in the aviation sphere were severed. Aircraft engine designer A. A. Mikulin, Main Directorate of the Civil Air Fleet chief I. F. Tkachev, and several TsAGI and Air Forces Academy aerodynamics specialists visited Germany in 1936-1937. Previous talks held in 1934-1935 were aimed at the purchase of two high-speed Heinkel He 70 mail and passenger aircraft. However, Hitler banned the deal since the German Air Ministry considered the airplane to be a prototype of a future bomber.
Several German military aircraft were brought from Spain for examination. Some were so badly damaged that they had to be examined on the ground, while others were restored and test flown. They even took part in simulated air combat with Soviet fighters. In 1937-1938, Air Forces Scientific Research Institute specialists familiarized themselves with He 51 and Bf 109 (with Jumo 210 engine) fighters, as well as Ju 52, Ju 86, and He 111 bombers.
In general, the results of testing gave some hope: the flight characteristics of the Soviet aircraft exceeded -those of German planes. As proof, I will provide a few excerpts from Scientific Research Institute reports on the results of the simulated air combat.
1. He 51 fighter (designated I-25, flown by Stefanovskiy in 1938 in the USSR): Despite its low speed (315 km/h), the I-25 can engage in active defensive combat against I-16, M25, DI-6, and DI-6Sh airplanes and be successful in a surprise attack on SB, DB-3, and R-9 planes, but it cannot retain the combat initiative. In combat against the I-16, the latter has all the advantages".
2. Bf 109B fighter (tested by pilot Suprun in 1938): "Tactical flight characteristics of the Messerschmitt-109 (as written in the document) powered by a Jumo 210 engine are lower than those of high-speed fighters in service with the RKKA Air Forces".
3. He 111 bomber (test flown by Kabanov in 1938): "1. The speed of the Heinkel-111 is lower than that of the corresponding domestically produced aircraft. 2. The Heinkel 111 rate of climb, range, and ceiling are significantly lower than what is required of modern two-engine bombers.
At the same time, Air Forces representatives pointed out the advantages of some construction elements and equipment on German aircraft: fiber self-sealing fuel tanks; oxygen equipment; and the crew intercom. But, what the military liked most of all was the Jumo 205 diesel engine installed in the Ju 86 bomber. Its fuel consumption rate and power-to-engine cubic capacity ratio noticeably exceeded those of the Soviet AM-34, M-25, and M-85 aviation engines. The Air Forces Scientific Research Institute even recommended that Jumo 205 engines be series produced at one of the Soviet plants.
The German airplanes tested in the USSR in 1937-1938 were examples of the technology of Spanish Civil War's first phase. New Luftwaffe aircraft—the Bf 109E powered by a Daimler-Benz DB 601 engine and the Ju 88 high-speed bomber —appeared in Spanish skies in 1938. They demonstrated clear superiority over the Soviet I-16 and SB.
It is amazing that, at the height of the Civil War in Spain, when the military confrontation between the USSR and Germany was at its peak, the government considered (and even approved) a project to grant to Lufthansa year-round concession rights for scheduled flights between Moscow and Berlin. This airline was to take the place of Deruluft from 1937 on. However, this plan was not implemented.
Of course, all these occasional tests, business trips, and cooperation projects were insignificant compared to the large-scale cooperation with the US and France, which were the main suppliers of Western equipment and aviation technologies to the USSR.
On 23 August 1939, everything had changed overnight when Hitler and Stalin signed the non-aggression pact between the USSR and Germany. Former sworn enemies became allies. An agreement to renew economic cooperation supplemented the military pact. The following was contained in a commentary published by the daily newspaper Pravda on 13 February 1940:
On February 11th of this year, an economic agreement between the USSR and Germany was signed in Moscow after successful negotiations. This agreement meets the desires of both governments to work out an economic program of barter between Germany and the USSR. Such wishes were expressed in letters between Comrade Molotov, Chairman of the Council of People's Commissars and Commissar of Foreign Affairs, and Mr. J. von Ribbentrop, German Minister of Foreign Affairs, exchanged on 28 September 1939.
The economic agreement envisions the export of raw materials from the USSR to Germany, compensated for by German exports of machinery to the USSR...
The agreement was signed for the term of 27 months. The USSR was to export forage grain, cotton, oil, phosphates, and chrome and iron ores. In exchange, Germany promised to familiarize Soviet technical specialists with its industry and export machine tools and manufactured goods, including examples of military equipment, to Russia based on orders placed.
The reasons for such sudden rapprochement between the USSR and Fascist Germany, and its political consequences, have been discussed repeatedly in the press and there is no point in bringing up this question again. Historians appraise this fact in different ways. However, one thing is absolutely clear. Experience from the final phase of the war in Spain demonstrated the clear superiority of German military technology over Soviet equipment. Stalin feared a •war with Germany and, taking every possible step to avoid it, banked on German know-how to reequip the Red Army from the technical standpoint.
The official signing of the economic agreement was a formality. A new phase of military and economic cooperation between the USSR and Germany had begun immediately after the signing the non-aggression pact and the subsequent capture of Poland. The Defense Commissariat back in October 1939 had compiled a preliminary list of German military equipment planned to be bought for examination. The section on aviation included Me 109 (Bf 109) and He 112 fighters, Do 215 and He 118 bombers, various trainers, Focke-Wulf helicopters, Jumo 211 and DB 601 engines, Junkers diesel aviation engines, different types of control devices, and armament. Moreover, the plan was to acquire several examples of each type. The total sum allocated for the purchase of military equipment in Germany was the astronomical figure of 1 billion German marks
At the same time, I.F. Tevosyan, a member of the Bolshevik Party Central Committee, led a large commission that went to Germany in October 1939 to study the achievements of the German aircraft industry and to select examples for purchase. Managers from different industries, designers, military specialists, and employees of scientific research institutes comprised the commission.
General A. I. Gusev headed the aviation group. It included N. N. Polikarpov, A.S. Yakovlev, V.P. Kuznetsov, A.D. Shvetsov, I.F. Petrov, P.V. Dement'yev, and S.P. Suprun, among others. As it was agreed, the German Air Ministry showed the majority of aircraft industry enterprises to the Soviet specialists. In just over a month, the delegation's members traveled all around the country, visited the production factories of Junkers (Dessau), Messerschmitt (Regensburg, Augsburg), Henschel (Berlin), Focke-Wulf (Bremen), Heinkel (Rostock), Arado (Brandenburg), Blohm und Voss (Hamburg), Dornier (Friedrichshaven), and Bucker (Ransdorf). They familiarized themselves with the engine production of BMW (Munich), Junkers (Dessau), Hirt, Argus and Bramo (all three in Berlin); visited factories making propellers (VDM, Schwarz plant), radiators for water-cooled engines (Behr plant), crankshafts (Krupp in Essen), piston rings (Goetze plant in Cologne), bearings (Admos plant), instruments (Aska-nia, Bosch, Siemens, Lorenz, and so on), aircraft armaments (Henschel, Siemens, IG Farben Industry), rubber and Plexiglas products (Continental plant, Plexiglas factory in Darmstadt); and visited the Scientific Research Aviation Institute in Goettingen and the Luftwaffe Scientific Testing Center in Rechlin.8 And this is not the entire list...
Just as the Germans hoped, the Soviet aircraft engineers highly appreciated the things they had seen in Germany. During a 27 December 1939 conference of the Technical Council of the People's Commissariat of the Aviation Industry, N. N. Polikarpov said "the German aircraft industry had taken a big step forward and had emerged in first place in the world". Not only the high quality of the German aircraft, but also the rates of their production worried Soviet leaders. In the opinion of L F. Petrov, Deputy Chief of the Air Forces Scientific Research Institute, German factories together with enterprises in occupied Poland and Czechoslovakia could, if necessary, produce 2500-3000 airplanes a month, more by a factor of three than the Soviet capability. (As it turned out later, this was an inflated estimate. During all of 1940, the Germans built 10,826 airplanes, including 7103 combat types. Prior to invading the Soviet Union, the Nazis accelerated the work of the aircraft industry and reached a production peak of 1174 airplanes in March 1941, whereupon production began decreasing. As a comparison, in 1940, the Soviet Union built 10,565 airplanes, including 8331 combat aircraft.)
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Soviet designers who had been to Germany thought that the high production culture, good labor management, and the excellent scientific and experimental foundation of the design offices, along with the work of scientific aviation centers in Goettingen and Rechlin, were among the reasons why Germany had achieved superb results in developing its aircraft industry. Here are extracts from the speech A. S. Yakovlev gave at the aforementioned conference:
Research and development work in Germany is very well organized. The DVL Institute is well ahead in its work. In some disciplines, the German designers have permission (prospects) and can look ahead a year or two. If we compare this with what we have, then it must be admitted that there are a number of questions the TsAGI has to work out and provide guidance to us, but we do not have any such guidance. ...The problem of radiators remains unsolved. Our radiators still are heavy and this does not allow us to provide a high-speed machine. This question is very murky and here the TsAGI only monitors. It does not provide a methodology allowing certain measures to be taken against it. This can be tested only on a manufactured airplane.
If we take the problem of airfoils, then we have two or three airfoil types and the designer holds on to them. No new atlas of TsAGI airfoils is planned until late 1940.
...German designers have wind tunnels at their disposal, where the main tests are run. They also have smoke tunnels where a number of practical questions can be tested. Then, every experimental plant designer has a strength laboratory and vibration laboratory at his disposal. We see that every designer tests aircraft parts, and the airplane as a whole, at his plant, in a testing shop. We saw many parts undergoing fatigue and buffeting tests on special machines. This way, the characteristics of individual parts are learned before the machine appears. ...Further, concerning strength standards. In Germany, there are exhaustive strength standards but, as we were told, they are not obligatory for the designer, they are consultative. If the airplane has been designed according to the strength standards and it turns out otherwise, you are responsible for it. If you act as you think best in using strength standards and the machine turns out well, then no one will make any particular complaints.
...Then, the exchange of experience is very helpful for German designers. The work is organized in such a way that every factory builds two to three types of designs. The Messerschmitt plant produces the Messerschmitt 109 and also makes wings (for other firms' aircraft). This applies to Heinkel and all others as well. This leads to a natural exchange of know-how and results in the German aircraft industry not being greatly exposed to some act of sabotage or an air raid as a factory that builds the machine as a whole, from the very beginning till the end. This circumstance is extremely important and is of great help to designers.
To our shame, we have to admit that almost all of us work very exclusively and there are no incentives for us to familiarize ourselves with what many other designers are doing. Very often we have to decide issues already solved by others and run into mistakes from which other designers have already learned.
...Besides having an opportunity to use the experience of other plants, German designers have other help and it is very significant. It is special technical literature and periodicals. Several scientific journals publish all modern materials. In addition they have remarkable books—reference books for designers. These are the most valuable works where you find solutions for a series of elementary things over which we rack our brains. We do not have this, which is sad....
Technological processes were also evaluated. There were things to learn since Germany had modernized its aircraft industry in 1935-1938. We believed that Junkers managed to organize production in the most rational way, where everything had been done to rapidly assimilate a model that had gone into series production. Of course, Soviet aircraft factories were interested in such industrial equipment as hydraulic drawing presses, gun-rivets, and drop hammers. Reports contained information that the German aircraft industry began using Dowmet-al alloys (both in castings and forged parts) and almost completely stopped using wood in airplanes.
Based upon recommendations of the delegation that visited Germany earlier, an order for German aircraft and equipment for their detailed examination in our country was arranged through the Commissariat of Foreign Trade in early 1940. It included more than 100 items. In particular, the plan was to acquire five He 100s with evaporative-cooled engines, five He 100s with water-cooled engines, five Me 109Es, five Me 1 lOCs, two Ju 88 and Do 215 bombers, Biicker Bii 131 Jungmann, Bii 133 Jungmeister and Fw 58 trainers (three of each type), a record-holder Me 209, as well as two Fa 226 helicopters. Each airborne vehicle had to be fully equipped and have a set of spare parts. Three spare engines were additionally ordered for each of the He 100, Me 109 and Me 110. Besides that, the plan was to get from Germany two Jumo 207 diesel aviation engines, two Jumo 211 engines, two 1400hp Daimler Benz boosted engines, examples of fuel injection pumps and nozzles, 1500 Bosch spark plugs, 10,000 piston rings, more than 1000 flexible gasoline and oil pipes, 30 propellers, many sets of test equipment (including five Braun Boweri high-altitude test facilities), gun sights, various types of bombs and ammunition for airborne armament, and so on and so forth. The delivery term for most items was 12 months; sometimes (the Me 209, for instance), it could be 15 months. The order totaled tens of millions of rubles. It is known that the Soviet government paid 25 million rubles just for some of the equipment that was delivered to the USSR by the summer of 1940."
The choice of aircraft bought for examination in the USSR was, in general, correct. Most of the aforementioned airplanes were widely employed by the Luftwaffe and for several war years were its backbone. Nevertheless, mistakes were made. The first was the heightened attention paid to the He 100 airplane that Germany passed off as a series-produced fighter superior in speed to the Me 109- The Russians swallowed the bait and ordered 10 He 100s in Germany, more than any other type.16 But, in reality, because the evaporative cooling system was not developed properly and an aircraft with wing surface radiators was highly vulnerable in combat, not to mention a series of other technological and operational deficiencies, the He 100 never entered operational service. It was designed as a racing airplane and remained such, despite the two machine-guns it carried. The following was noted in the conclusion of an Air Forces Scientific Research Institute report written when He 100 testing in the USSR concluded: "The airplane is not developed to the requisite level for combat duties".
The scornful attitude towards the Ju 87 dive-bomber was the second mistake. In his memoirs A. S. Yakovlev wrote: "When in October 1939 we were granted an opportunity not only to see, but to purchase the German aircraft, then these woeful tacticians flatly refused to buy the Ju 87. 'Why should we spend money for nothing? An obsolete, low-speed type,' were their arguments. However, on the first days of the war, these 'obsolete, low-speed machines' inflicted innumerable miseries on us".
And finally, the selection of the Do 215 instead of the more modern Do 217 is hard to understand. The Germans employed this airplane in limited numbers mainly for reconnaissance duties and withdrew it from production in 1941.
Many groups of specialists went to Germany in February-March 1940 to supervise this order, which was unprecedented in scope and variety. They included aircraft industry and scientific research institute managers, factory directors, test pilots, Air Forces representatives, specialists on engines, armament, instruments, radio equipment, and so forth — more than 40 persons in all.
At the Soviet delegation's request, General Udet allowed German pilots to ferry the aircraft to speed up their delivery to the USSR. Thanks to this decision, there was no need for long procedures to legalize the entry of Soviet crews into Germany. Flights were to be carried out via the well-known Berlin- Koenigsberg-Moscow route.
Soon all the ordered German aircraft were delivered to Moscow. Most of them came under their own power, while some (five He 100, in particular) came by train. The ordered engines, equipment and instruments were also shipped by rail. The "sanitary cordon" between the USSR and Germany no longer existed and deliveries of all goods were carried out unhindered and unmonitored.
The German aircraft and other aviation equipment were brought for examination to the Air Forces Scientific Research Institute, the newly founded Flight Research Institute (LII), TsAGI, TsIAM, and other organizations. Moreover, at the request of the People's Commissariat of the Aviation Industry, some airplanes were flown to factory airfields of aviation enterprises in Gor'kiy, Voronezh, Kazan', and Khar'kov. Many specialists came to Moscow to the Air Forces LII to see the airplanes brought from Germany. As V. Ye. Chertok, an engineer from Plant No. 293 in Khimki (subsequently a famous missile and aerospace designer who was one S. P. Korolev's closest assistants) provided his impressions:
We carried out the inspection of German equipment in groups, without haste. I was most interested in electrical equipment, piloting and navigational instruments, radios, bomb launchers, and bomb sights.
The other specialists and I were simply jealous of the neatly made instrument panels and consoles. The Siemens electrical bomb release unit was really beautifully designed... We turned the aircraft radios on and saw that air-to-air radio communications were reliable. Our airplanes in service for the most part did not have any air-to-air, or air-ground, radio communications.
First-hand familiarization with the German aircraft showed that the Soviet Air Forces, among the world's mightiest, were going through a crisis and taking a back seat to the German Luftwaffe.