A sharp increase in maximum speed compared to the previous generation of machines, in particular the MiG-19, gave rise to a kind of euphoria - both for the customer and for the management of the MAP. The support was at the highest level, since the interests of both the MAP coincided (after all, it needed high performance for reporting), and the customer, the Air Force (who quite reasonably wished to have a new machine in service that would become a worthy response to the "American challenge" in the person of fighters of the 100th series). It should be noted that the rivals in the person of OKB-155, headed by A. I. 5 with the standard R-11 engine. In the spring of 1956, the cars literally walked toe-to-toe through the stages of the factory test program, gradually increasing speed in an unofficial competition.
As a result, for some time the game went on, one might say, honestly, and the first winner (they, as already mentioned, became the Sukhoi Design Bureau) was given the right to launch the machine into mass production. Soon a government decree was issued, according to which the S-1 under the designation Su-7 was launched into a small series at the plant number 126 in Komsomolsk-on-Amur. By the mid-50s, this plant, like many others, was Mikoyan's "patrimony": here they produced the MiG-17 and prepared for the production of the MiG-19. But, unlike the "head" factories of the MAP No. 21 (Gorky) and No. 153 (Novosibirsk), it was as if it were not "native": it was located far away, and the production volumes were smaller, and the equipment was flatter … And therefore, the attitude to that that they were going to "take away" him, the Mikoyanites were quite calm. Well, the Sukhovites did not have to choose, and the set of working documentation was handed over to the serial plant on time. In 1957, even before the end of the tests, preparations for production began there.
State joint tests of the front-line fighter Su-7 ended on December 28, 1958. The Su-7 had a thrust-to-weight ratio of about unity and a wing load of 290 kg / m2. The aircraft developed a maximum speed of 2170 km / h and had a ceiling of 19100 meters, which was the best indicator for domestic aircraft at that time. At the same time, in the course of military tests, a lot of shortcomings, natural and inevitable for the head series, came to light. They demanded immediate elimination, both in production and in the ranks. To this end, a team of factory specialists modified the onboard systems and the airframe in parts with complete disassembly of equipment, loosening of electrical harnesses and their re-laying along new routes with thermal protection and soldering in the connectors. At the same time, the improved automatic control system ESUV-1V was introduced and the LFF was replaced with an expanded one due to the replacement of the AL-7F engine with the AL-7F-1 with a new automation system. As already mentioned, the mastering of the MiG-15 and MiG-17 series was carried out by plant No. 126 following the leading related enterprises, using their technological developments. But in the production of the Su-7, the plant acted as an independent serial enterprise, fully providing the design and technological development of the aircraft. Ultimately, the whole rush to launch a still very crude car in the series went sideways for the "seven" - the initial release plan was repeatedly thwarted due to the need for numerous improvements. In fact, in 1959, 96 Su-7 aircraft were manufactured.
Production vehicles carried armament consisting of two 30-mm NR-30 cannons installed in the root parts of the wing consoles with ammunition for 65 rounds per barrel (with an allowable cartridge sleeve capacity of 80 rounds). On the ventral beam holders of the BDZ-56F, two PTBs of 640 liters each could be suspended or, in overload, aviation bombs with a caliber of up to 250 kg. Since, due to the "gluttonous" engine, most of the flights were carried out with PTBs, two more BDZ-56Ks were installed under the wing for bombs of caliber up to 250 kg or ORO-57K blocks with unguided rockets. Initially, ORO-57K were developed at OKB-155 by A. I. Mikoyan for the MiG-19 fighter, but later found limited use on the Su-7. Each unit was equipped with eight 57-mm NARS S-5M with a high-explosive warhead. The projectile was detonated with a V-5M instantaneous mechanical percussion fuse. Aiming was carried out using an ASP-5NM aviation rifle sight, and to determine the range to air targets, the aircraft were equipped with an SRD-5M radio range finder installed in a container of a retractable air intake cone. The Su-7 equipment included the RSIU-4 radio station, the ARK-54I "Ilim" radio compass, the MRP-56P "Marker" marker radio, the SOD-57 and SRO-2 "Chrom" transponders, and the SPO-2 radiation warning station "Siren-2".
Meanwhile, competitors represented by OKB-155 A. I. Mikoyan more and more "stepped on the heels." As already mentioned, they were the first to start in the race for the best fighter - on February 14, 1955, test pilot of the OKB G. K. Mosolov lifted into the air an experienced E-2 with a swept wing and an RD-9B engine with an afterburner thrust of 3250 kgf, previously installed on the MiG-19. This was a temporary solution, since the projected E-1 fighter was supposed to be equipped with the new AA turbojet engine. Mikulin AM-11 with afterburner thrust 5110 kgf and delta wing - the last "squeak" of aviation fashion of those years. Due to the lack of thrust, the E-2 did not reach the set maximum speed of 1920 km / h and the ceiling of 19000 m. the speed was only 1290 km / h, and the ceiling was 16400 m. Against this background, the results shown by Sukhovsky S-1 looked more preferable. The E-5 cocked hat with a modified wing and the AM-11 turbojet engine (in the P11-300 series) did not correct the situation either. The aircraft, due to the still insufficient engine power, did not reach the TTT of the Air Force and was then regarded by the customer as unsuccessful and unpromising. The serial production of the E-5, which had already begun, received the designation MiG-21 in the series, was quickly phased out at the Tbilisi aircraft plant No. 31. At the same time, there were practically no complaints about the range of flight characteristics of the new Sukhov aircraft. Air Force Commander Air Marshal K. A. Vershinin on January 9, 1958, in a letter to the Central Committee of the Communist Party of the Soviet Union, indicated that "the Air Force, as a customer, is interested in fine-tuning a large number of experimental aircraft in order to be able to choose … In terms of flight characteristics, the Su-7 has an advantage over the MiG-21 in speed of 150 -200 km / h and the ceiling - 1-1.5 km, while it can be, after making minor changes, a fighter-bomber. The Su-7's coverage is more encouraging than the MiG-21."
It seemed that the fate of the MiG-21 hung in the balance, but the next day K. A. Vershinin together with the Chairman of the SCAT P. V. Dementyev sends another letter to the same address, but with a request to release 10-15 MiG-21s from the existing reserve. It is very difficult to understand the secrets of the "Madrid court". The last request was ignored. However, the MiG-21 was "rescued" by someone; it is quite possible that OKB-300 also said its word, arriving in time with a proposal for a forced version of the R11F-300 engine.
On July 24, 1958, Council of Ministers Resolution No. 831-398 and nine days later - GKAT order No. 304 on the construction of a MiG-21F aircraft (E-6, product "72" of plant No. 21) with an R11F-300 engine based on the MiG-21. The new R11F-300, the production of which began in 1958, had an afterburner thrust of 6120 kgf, acceptable reliability and made it possible to significantly improve almost all the flight characteristics of the fighter. May 20, 1958 V. A. Nefedov tore off the E6-1, the first prototype of the fighter, later designated MiG-21F. With a forced TRDF, a sharp leading edge of the air intake, a two-jump cone and other improvements, the MiG-21F developed a maximum speed of 2100 km / h, reached an altitude of 20700 m and had a flight range with one PTB of 1800 km. Its armament consisted of two 30-mm NR-30 cannons (the same as on the Su-7), NARS, bombs and incendiary tanks. The machine had good stability and controllability, it could be quickly mastered by pilots of combat units. In addition, with practically equal flight characteristics with the Su-7, the simpler and lighter (6850 kg versus 9245 kg) MiG-21F was better suited for the Air Force FA, since it had better aerobatic and maneuverable characteristics, a lower landing speed and, therefore, required airfields with a shorter runway (the takeoff run of the MiG-21F was 900 m, and the Su-7 was 1350 m). The R11F-300 engine turned out to be less susceptible to surging, the Achilles heel of the "seven", and the use of a promising delta wing at that time added more points to the OKB-155 fighter.
Meanwhile, the continuing problems with the AL-7F against the background of a new competitor did not add supporters to the Sukhov machine. It is quite clear from the tables below that Sukhoi has made a large fighter. Nevertheless, comparing his and Mikoyan's planes, it is clear that the maneuverability characteristics of the Su-7 turned out to be quite good. There is a significant advantage of the Su-7 in the bend radius, which persists with increasing altitude. But there is a slight lag in the rate of climb. The Air Force command was satisfied with the new P. O. Sukhoi. However, the military also supported Mikoyan's alternative project, which was better suited as a front-line fighter. Naturally, problems arose with the MiG-21, but the number of these aircraft in the Air Force units grew. In 1959, the aircraft was put into production at the Gorky aircraft plant №21, giving a start to the production of one of the most popular and famous jet fighters "of all times and peoples". And by the beginning of 1960, the factories had already built more than 200 (!) Machines. The concept of a light front-line fighter for air combat was winning. The MiG-21 was distinguished by an easier-to-operate power plant, lower fuel consumption, was less noticeable in the air, had better takeoff and landing characteristics, and for its adoption it was not required to increase the runways throughout the country, which ultimately predetermined the choice of the military …
In contrast to the success of the MiG-21F in OKB-51, on the basis of the experimental S-41, which reached a speed of 2230 km / h and a ceiling of 19,500 meters during tests, the project of the S-21 fighter was developed. But it never came to the construction of a prototype.
Well, what about the situation in the United States, with a constant eye on which military customers issued TT?
F-104G
In the United States, Johnson with his F-104 deviated greatly from the initial plans and instead of a light fighter created a manned rocket to achieve record performance. In general, the overseas rival turned out to be the most unsuccessful fighter. Actually, all this determined the further fate of the projects. The Americans took the non-maneuverable F-104A into service with the air defense units (and at the same time pushed it against common sense to the allies as the main one), the MiG-21 became the "workhorse" of front-line aviation, and the Su-7, as suggested in his letter to the Commander-in-Chief, began to remake into a bomber. The last "clean" Su-7 series 12 left the assembly shop in December 1960. A total of 133 fighters were built, of which 10 pre-production and the first 20 production aircraft had AP-7F engines. Considering the huge need of the Air Force for such fighters, the number of built Su-7s is simply scanty - they were in service with only two fighter regiments - 523rd and 821st. Both units were based in the Primorsky Territory, closer to the manufacturing plant. Some of the aircraft entered the Yeisk VVAUL, where pilot training was deployed. Officially, the Su-7 was never adopted.
Today, from the height of the past years, one can critically examine the results of the work of that time. I remember that in the 1960s there was a saying in aviation: "The designer is dry, the plane is wet, and the technician is wet", but we will try to refrain from hasty and lightweight conclusions. One could refer to "objective" factors that made it difficult for the designers to choose the general layout and parameters of the new machine. Such, for example, as the clearly overestimated requirements of the customer and his lack of a clear concept of using the aircraft, and the OKB team has a lack of practical experience in creating supersonic machines. Already in the process of construction and testing, the situation was greatly complicated due to non-fulfillment of tasks by subcontractors (first of all, engine operators), weighting of equipment and a decrease in its characteristics. But all this is everyday life and routine, since the buyer is not interested in the complexity of the seller, the quality of the product is important to him, and any design bureau can make such excuses.
All this, of course, does not relieve the designers of responsibility for the mistakes made in the design of the aircraft, but even here one should still distinguish between errors, so to speak, “conceptual”, associated with the general level of aviation science and ideas about the subject of design. Such claims can be attributed, perhaps, to the entire generation of aircraft, both Soviet and foreign. Much more interesting for us is the question - who and how solved these problems? As an example, it can be attested that in terms of airframe design, the Su-7 was an extremely reliable machine. According to the statistics of flight accidents, during the entire period of its operation in the USSR Air Force, there was not a single case of aircraft destruction in the air due to insufficient strength. And this is despite the fact that at the time of the design of the machine, the designers were practically unaware of the load repetition rates for this type of aircraft.
Serious "conceptual" errors include the relative imperfection of the aerodynamic layout (frontal air intake, and, consequently, large losses of internal volumes due to the long air channel; weak wing mechanization, and, as a consequence, deterioration of takeoff and landing characteristics, etc. etc.). These reproaches would be quite fair, since there is practically nothing to object to them, with the exception of the already mentioned references to the designers' lack of practical experience in the development of such machines and the firm, directive nature of TsAGI's recommendations for choosing the layout - only from those tested and worked out at the institute.
The underestimation of takeoff and landing mechanization is especially worth noting. This oversight, which led to high takeoff and landing speeds, was the "Achilles' heel" of all second generation aircraft, both Soviet and American. As a result, we had to fight hard to improve them, but it was not possible to fundamentally solve the problem. Another example is the adjustment of the air intake to ensure stable joint operation of the turbojet engine with an axial compressor and the inlet device. Here, the OKB learned from its mistakes, not knowing much then due to ignorance of the subject, and already during the tests found acceptable solutions to the problems. OKB-155 faced similar difficulties when testing machines of the "E" series.
More interesting is the question of choosing an engine. Was there an alternative to the AL-7F? As you know, Mikoyan, who created the machine of a smaller dimension, took the R-11F-300 as the power plant. And he made the right decision, because, despite a somewhat prolonged starting period, over time this engine reached the specified parameters (with the exception of weight), and in terms of reliability and resource it far outstripped its rival. How it all reminds of the story with front-line bombers … Of course, from the standpoint of today it is easy to condemn P. O. Sukhoi for his choice of the AL-7F, but is this justified? Indeed, at a time when the choice still had to be made, everything was by no means so obvious. To ensure the specified characteristics, instead of one AL-7, two R-11s would have to be installed, and this complicated and made the vehicle heavier.
The stake made by P. O. Sukhim on the AL-7F with high traction characteristics was justified when creating a high-altitude fighter, which this aircraft was originally intended to be. In this capacity, it would probably be in no way inferior to the T-3 interceptor, which was being created in parallel with it.
If, however, fantasize in the style of an alternative history, it is clear that the Su-7, due to its higher cost and higher requirements for the runway, could not have received the same widespread distribution as the MiG-21. At the same time, a larger midsection of the fuselage, in the event of a rearrangement of the nose of the Su-11 interceptor, would be able to accommodate a more powerful radar. Since 1973, the Su-7 fighter would most likely receive an R-23 missile and be able to fight at medium distances. From the same year, the Su-7 could be equipped with the P29-300 engine, which would increase the flight range to 1,500 km without outboard tanks. With outboard tanks, it would be possible to get quite a decent range. But the release of the updated Su-7 in these years would no longer make sense: with the same engine and in the same dimension, the more progressive MiG-23 was preparing for the series. I think that the Su-7 could not have become a long-liver like the MiG-21.
It is difficult to predict what performance the Su-7 could show in the Vietnam conflict. In close maneuvering combat, it was not inferior to the MiG-21. However, the large size would allow the F-4 pilots to detect it more often and earlier than the small MiG-21. This could be partially offset by a more powerful airborne radar, which was mentioned above. In addition, a more powerful engine produced a more powerful thermal footprint. It would be much more difficult for the pilot of the Su-7 to jettison the missiles with the IR seeker from the tail than his counterpart on the MiG-21. It is even more difficult to analyze the battle with Mirages. If the Mirages were pulling the MiGs into horizontal turns, then the Su-7 has an advantage here, but all the same, I personally find it difficult to imagine the best performance of Sukhoi. In any case, the management did the right thing by giving preference to the MiG-21 in this competition.
References:
Adler E. G. Earth and sky. Aircraft designer's notes.
Markovsky V. Yu., Prikhodchenko I. V. The first supersonic fighter-bomber Su-7B. "Get out of the shadows!"
Aviation and time // 2011. №5. "The plane of the era of jet classicism."
AviO. Anthology of Su-7.
Wings of the Motherland // Adler E. G. How the Su-7 was born.
Tsikhosh E. Supersonic aircraft.
Wings of the Motherland // Ageev V. On the threshold of the "second sound".
Astakhov R. Front-line fighter Su-7.
The history of aircraft designs in the USSR 1951-1965
