The official basis for the creation of A. N. The Tupolev front-line bomber "98" (Tu-98) became the already mentioned December government decrees of 1952. In accordance with the terms of reference, a high-speed front-line bomber had to have the following data: a maximum speed of 1300 … 1400 km / h when flying at an altitude of 10000 … 11000 m; a practical range of at least 2300 km with 3 tons of bombs; practical ceiling 13000 … 13500 m. In December 1955, the OKB A. N. Tupolev was supposed to submit the car for state tests.
It is safe to say that by the beginning of work on a supersonic front-line bomber A. N. Tupolev was much better prepared than others. Since the end of 1949, the A. N. Tupolev, together with TsAGI, carried out a whole series of theoretical and applied works aimed at substantiating the existence and selection of the main parameters of promising heavy aircraft designed to achieve high transonic and supersonic flight speeds. Work on the formation of the appearance of the new front-line bomber relied primarily on the TsAGI research of 1948-1952 on the wings with a large sweep angle. In the course of preliminary studies on the topic, in search of the most optimal solution for the aircraft, options with a wing from 35 ° to 55 ° were considered. Finally, for the project of the supersonic first-born, a swept wing with a sweep angle along the line of quarter-chords of 55-57 ° was chosen. The fundamental factor in choosing such a wing was that by this time the theory of such a wing had been largely developed at TsAGI. As a result, the layout designers and structural engineers of the Design Bureau, under pressure from the aerodynamics of TsAGI, settled on just such a wing. Although many leading experts of the Design Bureau, in particular, the "chief" strength specialist, Tupolevtsev A. M. Cheremukhin (and many strength specialists at TsAGI) knew as a first approximation that the choice of such a wing would entail a large number of design and operational problems. In TsAGI itself, there was also no complete unity on this issue: which wing, triangular or swept, is more optimal for supersonic machines from an aerodynamic and design point of view. At TsAGI, two directions collided: a group of V. V. Struminsky, for the delta wing - a group led by P. P. Krasilytsikov and R. I. Steinberg. At that stage, the arguments, the stock of theoretical groundwork, and most importantly, the authority of V. V. Struminsky, turned out to be stronger, the corresponding recommendations of TsAGI appeared and the first supersonic machines designed and built in the Tupolev Design Bureau ("98" and "105") received swept wings with a sweep of 55-57 °, a relatively large aspect ratio. The wing turned out to be quite difficult for the designers and showed its difficult disposition in operation: problems with rigidity, when flying at high speeds, flutter, etc. In the future, this choice was retroactively justified by the disasters of the American B-58 supersonic bomber. The operation of heavy aircraft with large swept wings required extensive research. The relative thickness of the wing profile had to be reduced to reduce drag when flying at supersonic speed, but such a wing turned out to be either too heavy or not rigid enough. In an effort to ensure high aerodynamic quality of the wing at cruising supersonic modes, the developers abandoned the location of the main landing gear in the wing and completely placed them in the fuselage compartments. At the same time, there was a search for the most rational placement of engines, air intakes, as well as the choice of the type of engines. As alternative options for the power plant, there were provided two "twin" Mikulin AM-11 engines or two Klimov VK-9 engines. As a result, we settled on two AL-7 engines. Two AL-7 engines (later AL-7F with non-afterburner thrust 6500 kgf and afterburner thrust 9500 kgf) were located in the rear fuselage, and the air intakes were located on the sides of the fuselage in front of the wing. The requirement to achieve supersonic speeds also made it necessary to abandon all sorts of additional superstructures on the fuselage: they completely abandoned the turret fuselage cannon installations, leaving only the stern installation, the dimensions of the cockpit lights in the spirit of the times were minimized as much as possible.
The placement of powerful turbojet engines with afterburners in the aft fuselage required air supply to them through long air ducts, the introduction of air intakes with fixed central bodies in the form of small half-cones at the inlet and the use of a boundary layer drain system made in the form of a gap between the air intakes and the fuselage. In general, the new scheme was more than innovative, especially for such a conservative designer as A. N. Tupolev. To reduce the wave drag in the transonic zone, the aerodynamic layout of the "98" aircraft provided for a slight compression of the fuselage in the area of its articulation with the wing, which corresponded to the "area rule" that was then part of the practice of world aircraft construction. It should be noted that in Western publications the discovery of this law in 1954 is attributed to the Americans, although this rule was used in the layout of various elements of the A. N. Tupolev since the 40s with the Tu-2, having given the greatest effect on the Tu-16. This can be clearly seen even from photographs. (Another myth about US priority.)
For the first time in the practice of A. N. Tupolev agreed to the introduction of irreversible boosters on his plane in all control channels (the boosters were developed under the leadership of Chief Designer T. M. Basht in a specialized design bureau). The entire aviation industry knew the "great" dictum of Andrei Nikolaevich: "The best booster is the one that stands on the ground. The booster is good for a steam locomotive," very low reliability, and in addition, the managers did not yet know how to competently build aircraft control systems with irreversible hydraulic boosters). Simultaneously with the transition to irreversible boosters, spring loaders and steering dampers were installed in the control system. The crew of the aircraft, which consisted of three people, was provided with ejection seats. For the first time in practice, the OKB on a Tu-98 aircraft used a stern cannon installation with two AM-23 cannons, remotely controlled by a gunner from the cockpit. A PRS-1 "Argon" radar sight was used to guide the barrels of the stern defensive installation. In front of the fuselage, another AM-23 cannon was mounted, from which the pilot fired. An antenna of a panoramic-sighting radar of the "Initiative" type was located under the cockpit in a radio-transparent fairing. All strike weapons were located inside a rather capacious bomb bay and on external suspensions. The bomb armament system provided for the following loading options: 24 FAB-100 bombs, of which 8 were on the external sling, or 16 FAB-250, of which 4 were on the external sling, or 10 FAB-500, of which 2 were external sling. The missile system provided for the placement of unguided rockets in the bomb bay and on external suspensions in the following combinations: up to 300 NURS type ARS-85, or up to 61 TRS-132, or up to 18 TRS-212. NURS was supposed to be placed in special installations of the type used on an experienced attack aircraft - dive bomber "91". In the variant of use in the maritime theater of operations, the "98" aircraft was supposed to be armed with PAT-52, MAN, MAV and TAN-53 torpedoes, as well as with AMD-500 and AMD-1000 mines. Aiming during bombing was carried out using an OPB-16 optical sight, synchronously connected with the Initiative radar.
The construction of the prototype aircraft at the plant No. 156 was completed by July 1955, but until February 1956 the car was waiting for the AL-7F turbojet engine. It should be noted that this engine during the indicated period of time was absolutely "raw", not ready for serial production. Plant No. 45, which received an assignment for its development, managed to produce several dozen products by the end of the year, but due to repeated cases of destruction of turbine blades, all AL-7Fs were returned to the manufacturer with penalties. The question of replacing the AL-7F in production with V. Ya. Klimov, but their reliability also left much to be desired. The finishing of the AL-7F was continued at two plants (experimental # 165 of the AM Lyulka design bureau and serial # 45), and the serial design bureau received broad powers to make changes. It was a gesture of despair.
Only at the end of the spring of 1956 did the experimental Tu-98 receive engines manufactured by Experimental Plant No. 165. After the completion of the installation of the turbojet engine and the implementation of the relevant checks, the car was transported to the LII airfield. September 7, 1956 pilot V. F. Kovalev and navigator K. I. Malkhasyan performed the first flight on Tu-98. The flight tests were rather difficult. Difficulties with the A-pillar control system were identified. The landing gear of the aircraft was made according to a three-support scheme with a nose wheel. The nose strut with two paired wheels was retracted into the compartment under the cockpit back upstream. The main landing gear struts were attached to the powerful beams of the bomb bay and retracted back into the fuselage compartments, while the four-wheeled chassis bogies, together with the struts, occupied a horizontal position in these compartments. This innovative design solution made it possible to obtain an aerodynamically clean wing, free of landing gear units. However, the chassis of this design had a small track and was very difficult for flight operation in the Air Force, primarily due to significant crosswind restrictions and the need to train highly qualified pilots (the standard phrase of all factory flight test reports is "available to intermediate pilots" for this aircraft obviously did not fit anymore). As an engineering solution, such a landing gear design was original and interesting, and later, when the second aircraft came to TsAGI for statistical tests, the chassis design of the 98 aircraft aroused keen interest among specialists from other domestic aircraft design bureaus, but there was no direct repetition of this design. In addition, the narrow-gauge landing gear layout made the aircraft virtually uncontrollable on slippery runways. In total, until the end of 1957, it was possible to complete 30 flights. In one of them, the Tu-98, breaking the sound barrier, reached a speed of 1238 km / h at an altitude of 12000 m.
Meanwhile, in December 1956, the General Staff formulated new proposals for the appearance of a promising front-line bomber. An opinion was expressed about the expediency of having two types of vehicles in service: a high-altitude high-speed front-line bomber with a maximum speed of about 2500 km / h, a working ceiling of 25000 … speed 1100… 1200 km / h and flight range up to 2000 km. It was planned to arm it with an air-to-ground K-12 projectile with a launch range of 100 … 150 km and a speed of up to 3000 km / h.
As you can see, in the four years that have passed since the beginning of the creation of the Tu-98, the Tupolev project has ceased to suit the customer (the same thing happened with the Il-54). In order for the machine to at least to some extent meet the requirements of the Air Force, it was necessary to sharply increase its flight speed and modernize the strike weapons system. New, even more powerful engines were nowhere to be found. The only real way to increase the aircraft's flight speed was associated with a radical reduction in the flight mass, and therefore with an inevitable decrease in the range and combat load. In July 1957, specialists from the Tupolev Design Bureau began developing a lighter and faster version of the "98A" (Tu-24). They planned to revise the design of the airframe, remove the cannon armament, and reduce the crew to two people. The takeoff weight should have been reduced by about 30%. Working on the Tu-24, the designers tried to eliminate many of the shortcomings of the base machine. So, the main struts began to be retracted into the wing fairings, so the track became wider, and the stability of the car at the stages of the take-off and run should have increased significantly. The aerodynamic forms of the bomber have become more perfect.
With a proposal to create a Tu-24 A. N. Tupolev appealed to the country's political leadership. Signed by R. Ya. Malinovsky, K. A. Vershinin, P. V. Dementieva and A. N. Tupolev on January 9, 1958, a letter was sent to the Central Committee of the CPSU with the following content: We are reporting considerations about the need to accept for production a front-line bomber Tu-98A (lightweight) … As a front-line bomber, as well as a bomber for naval aviation, at this time, the developed design bureau can be adopted under the leadership of Comrade Tupolev, on the basis of the Tu-98 aircraft, the Tu-24 (Tu-98A) aircraft with the following data: take-off weight 28-30 tons, maximum speed 1700-1900 km / h, practical flight range with a cruising speed of 950-1000 km / h - 2000 km (2400 km in overload), a practical ceiling with forcing engines 16-17 km, bombs weight 2000-3000 kg The aircraft is adapted for launching shells and using atomic bombs …
The aircraft has good ground cross-country ability. The aircraft's performance data in terms of speed and altitude exceed those of front-line bombers in service with the US and British Air Forces.
Entering into service with the Tu-24 will dramatically increase the combat effectiveness of front-line and naval aviation …"
The ink on the signature of the GKAT chairman P. V. did not have time to dry. Dementyev, as he … turned to the Deputy Chairman of the Council of Ministers D. F. Ustinov with a directly opposite proposal: The prototype of the Tu-98 front-line bomber has a maximum speed of 1200-1380 km / h, a flight range at a speed of 900 km / h at an altitude of 14-15 km - 2400 km, a flight weight of 38 tons.
To improve the flight performance of this aircraft, Tupolev proposed, by lightening the design and reducing the weight of the bombs, to reduce the flight weight to 26-28 tons, increase the maximum speed to 1800-2000 km / h, the ceiling to 17-18 km and the range to 3500 km. He proposes to complete the prototype of the improved aircraft by the end of 1959 and, without waiting for the results of flight tests, to launch this aircraft into serial production according to the OKB's drawings.
Reducing the flight weight from 38 tons to 26-28 tons will require practically a new aircraft and will load most of the OKB for a long time …
In accordance with the Decree of the Council of Ministers of the USSR of March 28, 1956, Yakovlev built a light front-line bomber Yak-129 with two P11-300 engines weighing 13-14 tons with a maximum speed of 1600-1800 km / h, a practical ceiling of 16-17 km and a range of 2400 km at a speed of 900 km / h. The Yak-129 aircraft is undergoing factory tests. In addition, by the Resolution of the Council of Ministers of August 15, 1956, Yakovlev was obliged to build a light high-altitude supersonic bomber with a flight weight of 20-22 tons with a maximum speed of 2500 km / h and a practical ceiling of 20-21 km. In the draft of the presented plan for experimental construction, we propose to build this aircraft as a carrier of projectile aircraft with its transfer to state tests in the fourth quarter of 1959.
Taking into account the front-line bomber built by Yakovlev and the existing task for a new carrier bomber at a speed of 2500 km / h, I consider it inappropriate to carry out further work with the Tu-98 aircraft. The State Committee considers it more expedient to concentrate all the means and forces of the OKB and Plant No. 156 in 1958 on the fulfillment of more important tasks set by the Government …"
After this letter, the question of further work on the Tu-24 ceased to be relevant. What made Dementyev change his point of view so dramatically? Perhaps he really analyzed the workload of the Tupolev Design Bureau and came to the conclusion that the distribution of his efforts was irrational. Perhaps the special relationship between Dementyev and Yakovlev was influenced (at one time they were both deputy ministers of the aviation industry and closely interacted)? Be that as it may, the Tu-24 remained only in the project, but on the basis of the studies carried out by the OKB A. N. Tupolev subsequently created the Tu-128 heavy interceptor.
Even during factory tests, the Air Defense Aviation Commander, Marshal E. Ya. Savitsky. After getting to know him better, he came to A. N. Tupolev with a proposal to create an air defense aviation aircraft structurally close to the "98th" aircraft, but with a completely different purpose. The air defense urgently needed a long-range fighter-interceptor armed with heavy air-to-air missiles and equipped with a powerful airborne radar system for detecting air targets and guiding airborne missiles at them. The decision to create a long-range intercept complex Tu-28-80 extended the life of the experienced Tu-98 already as a flying laboratory for testing the weapons system of the new interceptor. In the order of the State Committee for Aviation Technology, dated September 1958, it was said, in particular: "… Create an experimental laboratory aircraft on the basis of the experienced Tu-98 for testing the jet weapon control system in flight, starting its flight tests in the first half of 1959. Work on Tu-98 to stop …"
Specifications:
Crew: 3 people.
Length: 32,065 m.
Wingspan: 17, 274 m.
Maximum speed: 1365 km / h (1.29M).
Practical range: 2440 km.
Service ceiling: 12,750 m.
Armament:
Shooting and cannon:
1 × 23 mm cannon AM-23 with 50 rounds, in front.
2 × 23 mm cannon AM-23, in the aft installation DK-18.
Unguided missiles: 300 × TRS-85, 61 × TRS-132 or 18 × TRS-212.
Bombs:
4 × FAB-1000 in the bomb bay.
10 × FAB-500 (of which 2 are suspended).
16 × FAB-250 (of which 4 are suspended).
24 × FAB-100 (of which 8 are suspended).
Torpedoes: RAT-52, MAL, MAV, TAN-53.
Mines: AMD-500 or AMD-1000.
