In the spring of 1943, the writer was requested to accompany a technical mission to the USSR as a representative of the Bell Aircraft Corp's engineering department. Our group arrived in Russia on Aug 10 and remained for approximately four months. During our stay, our headquarters were in Moscow, where the writer was present at several meetings with the Technical Staff of the Red Air Forces, had an interview with a prominent Soviet designer, and visited a branch of the Central Aerodynamic & Hydrodynamic Institute. In addition, two trips were made by air one from Moscow to a larger fighter base near the front line, the other to a large training center.
Purpose of our trip was to observe the Airacobra in action, to discuss any engineering and service problems that might have arisen in operation of the P-39 in Russia, and to learn what design improvements in the Airacobra and later Bell fighters seemed desirable in the light of Russian experience.
The Bell P-39 fighter was first sent to Russia as a result of a Lease-Lend transfer from England of a relatively small number of airplanes. These planes were assembled and flown at a base near Moscow in the winter of 1941-1942. We were introduced to some of the Russian officers who had directed this work and were told some of their early experiences. It is to the credit of the Red Air Forces technical staff and to the designers of the airplane that no serious difficulties were encountered, although it was not possible at that time for a Bell representative to be present. In fact, until last spring no Bell or Allison representative had visited the USSR, although many P-39s and Allison engines were in use.
We found that the Airacobra was performing very well as a short-range fighter at medium altitudes, although at times it is used for other purposes. Usually Russian attack airplanes are employed for strafing and low-level bombing attacks, rather than fighters.
As a Russian fighter, the P-39 is lightened by omitting the wing guns and by using somewhat less radio than is installed at the Bell factory. Certain modifications were necessary at first for earlier P-39 models because of the rigors of winter on some parts of the front, but most of these are now incorporated into the airplane's design.
In most respects, however, the P-39 as operated in Russia is identical with its sister ships in the South Pacific and other American war theaters. The original paint is altered only by replacing the American insignia with the Red Star, and the original decalcomanias which locate points for servicing operations and items of equipment are permitted to remain in English, even though at first sight they must be as confusing to the Russian mechanics as even the most familiar words were to us when written in the Russian alphabet.
The huge task of translating service literature from English to Russian is carried out continuously by technicians of the Red Air Forces. While the translation of the rapidly changing terms of our technical aeronautical language into any other language is always quite exacting. we found that once the alphabet is learned, the Russian language is not quite so formidable as it at first appears. The Airacobra's record in combats with German fighters, dive-bombers, and medium bombers is very good, some Airacobra pilots having as many as 30 victories to their credit. For the most part, fighting conditions vary from those encountered in North Africa, Italy, and the South Pacific in that the country is quite level, which permits installing airfields close to the front lines, so that operations rarely require the use of auxiliary fuel tanks. It is thus more frequently possible for the pilot to land back of his own front lines in spite of severe damage to airplane structure or power plant.
Combats usually take place at altitudes of 15,000 ft or less, rather than at the extreme altitudes sometimes required in other theaters. It is characteristic of the fighting in Russia that comparatively little long-range strategic bombing has been carried out by either side.
Russian airplane production is concentrated chiefly upon single-engine fighters, such as the Yak-9 and La-5; twin-engine dive bombers and medium bombers, such as the PE-2 and DB-3; the well-known single engined Stormovik attack airplane; and military versions of the Douglas DC-3.
Although the bulk of Russian-operated airplanes are Russian built, these have been supplemented by American planes which are of similar types, except that the Stormovik has no close American counterpart. They are operated in Russia without the help of American technicians, other than for several brief visits by technical advisors.
An excellent opportunity to see several modern Russian fighters and the PE-2 dive bomber at close range and to compare them with Allied and enemy types was afforded the writer at a branch of the Central Aerodynamic & Hydrodynamic Institute, which is in many respects a counterpart of our NACA.
This exhibit is permanent and intended to acquaint Russian aeronautical designers with arrangements, mechanisms, and methods of construction which are used by others. To make the interior details easier to see, much of the wing and fuselage covering material is removed on one side of the aircraft's plane of symmetry.
At the exhibit, undesirable as well as desirable characteristics are indicated, such as units which are installed so that they are difficult to service or remove. It was the writer's impression that the Russian airplanes were simplest, the German airplanes were best designed for servicing, and that American airplanes, characteristically, contained the most radio equipment, the best heaters and avigation instruments, and were better adapted to a wide range of operating conditions.
Russian airplanes, particularly the Stormovik and fighter types, employ wooden plastic-bonded construction extensively, or mixed wood, duraluminum, and steel structures. The most notable example of mixed construction is the Yak-9, which has wooden wing covering and ribs, steel and duralumin spars, a steel tube fuselage, and duralumin tail surfaces.
Russian fighter types employ cannon and heavy machine guns mounted near the center line of the airplane, and they are comparatively lightly armed and armored. Their low weight-to-power ratios result in good rates of climb, while their top speed is approximately the same as that of opposing enemy fighters. As noted above, Russian fighters are comparatively unencumbered by radio equipment, blind flying equipment, elaborate starting systems, heaters, life rafts, etc. Wing loadings and landing speeds are about the same as those of American fighters.
The use of wooden construction apparently involves some, but not excessive increases in structural weight. Its resistance to explosive projectiles is poorer, although the damage done by solid projectiles is comparable with that done to duraluminum structures. The extensive use of wood for smaller types of airplanes is apparently dictated by shortages of duraluminum, machinery, and skilled labor.
In early September, our group was flown to a large fighter base on the central front, from which Bell Airacobras, Douglas A-20s, and a variety of Russian fighters were being operated. There we were given opportunities to discuss the Airacobra with pilots and technicians.
We were introduced to the pilots and technicians of the P-39 squadron at the base. The pilots were apparently about the same age as those performing similar duties in our own AAF, although some of the technicians appeared to be younger and the latter group included several girls. The writer was impressed by the difficulties of performing maintenance operations under combat conditions, with little shelter available in which to work. Since most combat operations take place during the day, it is common to service the airplanes at night.
In discussions which took place with pilots and technicians, we were made acquainted with the good and bad points of the Airacobra as operated at that base. Certain difficulties were noted to be peculiar to operating conditions in Russia. Necessity for the use of very-high-octane fuels was particularly objectionable, since such fuel is not required for Russian-built airplanes and thus presents a special transportation difficulty.
To an American, the entire transportation problem in Russia seems staggering, since few good roads exist between populated places. This puts a very heavy load on the railroads and results in extensive use of transport airplanes to move personnel and light types of equipment. There can be no doubt that the large Lease-Lend exports of all-wheel-drive American Army type trucks is of great importance in the success of the recent Russian drives because these vehicles are capable of operation on very poor roads.
It seems probable that in postwar development of the Soviet Union, the transport airplane will play a very important part, inasmuch as the present railroad system is likely to be expanded only where the tonnage to be transported precludes the use of airplanes and highway transportation.
Shortly after returning to Moscow we began another trip, being transported in a Russian-built Douglas to a training center about 180 mi away. Here we were acquainted with the best and worst points of the P-39 from the standpoint of the instructor-pilots and local maintenance men. We were able to exchange service information and describe changes that had been made, in order to overcome the maintenance difficulties which the Russians were then experiencing, on airplanes then on the production line. Here again the general impression was gained that the P-39 was performing well.
As has been obvious in our experiences with airplanes that are operated by our AAF, training and combat service often result in differing types of service troubles; for instance, training units have more difficulty with brakes and landing gear. It was noted that Russian technicians, even at advanced bases, usually must make repairs with fewer powered tools than would normally be available to our own technicians.
After returning from the training base, the writer was given the opportunity to discuss design problems with Alexander S Yakovlev and Prof Shiskin, the latter a prominent Russian aeronautical engineer, and the former a designer of fighter airplanes who is best known for the Yak-1 fighter and its more recent versions, including the Yak-7 and the Yak-9 mentioned earlier in this article. These are single-engine fighters powered with a liquid-cooled V-12 engine. The Yak-1 was first used in 1941.
We discussed the combination of metal spars with wooden skin and ribs that is used on the Yak-9, in which a thin strip of wood is riveted to the spar caps and the wood covering is then glued to the strip. I was told that the Yak-1 originally had an all-aluminum-alloy wing of conventional construction, but that material shortages had forced a redesign in wood. The present type of construction was adopted after running careful vibration tests of sample parts, and in actual service very little trouble has been experienced.
It was mentioned that flutter speeds were likely to be low for wooden wings. Prof Shiskin agreed and said that they made an extensive flutter analysis of each new design.
It was indicated that the flight load factors for fighter aircraft that are used by Russian designers are slightly higher than are used for US Army fighter types and that the height of drop for the landing gear is greater. However, no landing load factor is specified but depends upon the shock-strut characteristics.
It is quite likely that we can learn much about front line air warfare from the Soviet Air Forces, which have made very successful use of certain specialized types of airplanes. The most outstanding of these is the Stormovik, or Il-2, a very heavily armed and armored single-engine attack airplane. Escorted by fighters, it operates at low levels and deals very effectively with artillery positions, machine gun nests, and tanks. Although relatively slow and not highly maneuverable, its ability to resist the effects of small caliber fire permits it to operate at heights of about 80 ft from the ground, where it is fairly safe from large caliber anti-aircraft installations. Its heavy armor plating forms the forward fuselage structure, and it is equipped with bombs in wing bomb bays, cannon of from 20 mm to 37 mm, machine guns, and rocket guns.
During the present war, there has been considerable interest among American engineers in Russian aeronautical developments, and several articles have been published dealing with Russian airplanes, though they unfortunately often have contained inaccurate or obsolete information, partly because of language difficulties and the fact that the information was gathered by writers having insufficient technical training.
In postwar years, it is to be hoped that such difficulties can be overcome to the extent that more accurate articles are published dealing with Russian airplanes and with Russian technical progress.
This article was originally published in the May, 1944, issue of Aviation magazine, vol 43, no 5, pp 122-123, 249, 251, 253.
The original article includes 4 photos: