Creation of the "150" front bomber with sweptback wing became the last OKB-1 task. In contrast to the machines described above, it was not a development of WWII German aircraft but represented an absolutely new design using the latest achievements in science and technology of the second half of the 1940s. In addition to German specialists from experimental plant OKB-1, leading TsAGI scientists took part in this work. Among them were V. N. Belyaev, A. I. Makarevskiy A. K. Martinov, G.P. Svishchev, S.A. Khristianovich, and engineers from VIAM and some other organizations.
The "150" prototype was developed from the RB-2 design initiated by Baade and his assistants in 1948. This 30-ton machine with two TR-3 turbojet engines was to have an estimated speed of about 1000 km/h.
The design was scrutinized at TsAGI and approved in general although control system and tail unit changes were recommended to improve aircraft stability and controllability. The modified version received the plant designation "150". In 1949 a mockup was made and working drawings began to'be issued.
The bomber had a high sweptback wing, T-tail, two turbojet engines mounted on pylons under the wings, and crew of four. It was armed with three paired cannon turrets.
The fuselage consisted of three parts. A pressurized cockpit forward accommodated a pilot, a co-pilot (he also was the radar operator), and a gunner who used a flexible periscope gun sight for laying the upper gun turret. The cockpit was protected by armor from below. The aft portion had another pressurized cabin housing the radio operator/gunner.
The bomb bay was in the center and could accomodate up to 6000 kg of bombs, or extra fuel tanks.
The wing had a 35° sweepback at quarter chord line. It was of monocoque construction with panels stressed with inner corrugation. Fuel tanks were placed in the center-section. High-lift devices comprised two-segment trailing edge flaps. The ailerons and elevators were of a three-segment construction, and the rudders had two segments. This separation into segments was done to enhance the machine's combat survivability.
While the "150" was being designed, a debate ensued concerning the type of engines the bomber should have. B. Baade advocated use of powerful 8000 kg AM-03 turbojet engines designed by A.A. Mikulin while S.M. Alekseyev suggested use of the A. M. Lyul'ka AL-5, which were less powerful but, on the other hand, had less drag because they were smaller. After lengthy discussions, the second alternative was chosen.
The aircraft's control system - an irreversible hydromechanical type - was rather unusual. The pilot operated hydraulics cocks through stick and pedals and the hydraulic fluid entered hydraulic motors from both sides in turn, changing the direction of their rotation. The hydraulic motors activated control surfaces through a reducer and gearing system.
Since there were no analogous control systems in the aircraft industry, this device underwent considerable testing. The tests were carried out not only on a specially built test rig but also on a Ju 388 aircraft the plant used as a "flying laboratory".
The "150" was the first aircraft with pylon-mounted engines in the USSR Such a configuration made it possible, on the one hand, to make the wing aerodynamically clean and improve its lifting qualities, and, on the other, to use the forward-positioned engines as anti-flutter loads.
The "150" design also featured new bicycle landing gear. In 1949 it was tested on the Alekseyev-designed 1-215 prototype fighter. At Baade's suggestion, the back leg was designed such that its height could be reduced at takeoff, thus decreasing the takeoff run thanks an angle of attack enhanced by 3°.
Among other technical innovations, the aircraft featured fuel tanks of cellular construction preventing the fuel from rapidly flowing out of damaged tanks, T-tail, new high-explosive action fire extinguisher system, and wide use of parts made from the new B95 duralumin alloy.
The process of building the aircraft dragged on for a very long time thanks to all these innovations. While the possibility existed to use parts from prototypes when the EF-131 and EF-140 aircraft were being designed, now everything had to be created practically anew. There often was a need to turn to other plants for help. As a result, the first prototype was not finished until late 1951. Soon the second one designated for static strength tests was ready.
The size of the airfield at Borki did not permit the testing of such heavy aircraft as the " 150" (its takeoff weight of 38 tons was greater by a factor of 1.5 than that of the "140"). That's why the bomber had to be dismantled after ground tests and transported to a new airfield at Lukhovitsy. more than 200 kilometers from the plant. Transportation, assembly, and flight preparation took several months.
Aircraft "150" took to the air on 5 September 1952 and by late autumn eight flights had been made. Their results were promising but soon the snow precluded testing being completed by the end of the year.
Flights began again in the spring of 1953. Pilots Ya. I. Vernikov and D. V. Zyuzin performed the tests. In April, during the 16th flight, thanks to premature braking action, the aircraft touched down with locked wheels and skidded. But everything ended well enough and. after the damaged wheels were replaced, new flights began.
A misfortune happened on Victory Day, 9 May. during the 18th test flight. On the landing approaching into the sun, Vernikov miscalculated the landing path and pulled the stick backwards too early. The aircraft pulled up, lost speed, and hit the run-way from a height of 5-10 meters. No one was injured but the landing gear was broken (here, the back leg pierced the fuselage), and the engines and lower fuselage damaged. After the incident, Vernikov was demoted from Pilot 1st Class to Pilot 2nd class.
Although flight-testing ended with failure, the flights showed that on the whole the bomber conformed to technical specifications and even exceeded some of them.
Despite this, the Ministry of the Aviation Industry decided not to restore the damaged aircraft and ended the testing. At the time of its development being an advanced aircraft, by 1953 Aircraft "150" was no longer of interest: by this time, the Tu-l6 jet bomber, which outperformed the Baade airplane in all aspects, had been successfullv tested.
The damaged bomber was turned over to the Moscow Aviation Institute as a training aid (some of its fragments are still there) and its drawings were sent to the Tupolev, Beriyev, and Antonov experimental design bureaus.
D.A. Sobolev, D.B. Khazanov
- "The German Imprint on the History of Russian Aviation " /D.A. Sobolev, D.B. Khazanov/