Because the People's Commissariat of the military aircraft industry proposals for copying Me-163 did not expect, and tried to "pre-emptive strike." In the plan for the construction of an experimental aircraft for 1946 year, Approved February 26, 1946 Decision of the CPC № 472-193, included two almost identical design assignment missile interceptors.
Experimental Design Bureau of AI Mikoyan (OKB-155) tasked to design and build a single-seat fighter-interceptor cabin altitude, liquid rocket engine and the subsequent flight tactical features: in the land equal to the maximum speed — 1100 km per hour (M = 0.895), the maximum speed at an altitude of 10 thousand . m — 1,000 km / h (M = 0.93), the duration of flight in the small rod — 18 min. at maximum thrust — 5 min. ceiling with balance fuel at 1.2 min. — 17 thousand meters of the climb to a height of 17 sq m — 3.2 min., Weapons — two 23 mm cannons. The period for filing the first copy of the flight test — Nov. 1, 1946.
Ah well described the situation with the design of missile interceptor-270 in the report of the plant number 155 (Mikoyan OKB-155) for the year 1946:
"In the initial draft provided swept wing aircraft. Following the TsAGI calculations and research was identified scarcity of data for the detailed design of the wing itself, which was a prerequisite for a full review of aircraft project with the introduction of direct 9 per cent of the wing (March 1946 years). Forthcoming study of the Central hydrodynamic Institute revealed the inability to obtain a sufficient number of initial data for the aircraft with the wing. The work was suspended, revised the draft anew under the wing of a 12 percent (April 1946). In the coming work hampered obtaining aerodynamic and strength data on this wing. Using the geometry of the wing tips have approved the final on August 8. "
OKB Mikoyan OKB Lavochkin Unlike prefer to use conventional cannon gun. On the plane I-270 decided to install two guns NS-23 (115P) 23-mm gun with 40 rounds of ammunition and two Quadruple launchers (in German) for firing rockets.
In contrast to the Lavochkin, Mikoyan from the construction of its own missile interceptor-270 refused. Work on the fighter began in November 1945. The fighter was designed for parts of the air defense of military bases and large industrial facilities. By the end of March next year was finalized assembly of the machine, which has received factory code "F". And then began the ready drawings for the layout.
In April Belyaev VM was appointed chief engineer of the aircraft. Tips on TSAGI this month extended forward fuselage. It was made for a more streamlined aerodynamic shape. Layout by mid-May was made, and the 17th of the representatives of NII Air Force held its preparatory examination. In their observations was carried revision layout. Preliminary design of the aircraft was ready at the end of May 1946.
By calculations of the maximum speed interceptor near the ground was to be 1,000 kilometers per hour (M = 0.815), at an altitude of five thousand meters — 990 kilometers per hour (M = 0.86), 11 sq m — 925 km per hour (M = 0.87) and 15 sq m — 936 km per hour (M = 0.88). The plane was due to marked elevation gain of 88.5 sec., 150.4 sec. and 181.25 s. respectively. Service ceiling — 17,970 m, at an altitude of 15 thousand meters maximum flight duration was 4.14 (4.89 *) min. Takeoff — 895 m path length — 956 m Landing speed with the use of flaps — 137 km / h, without them — 156.5 km / h Empty weight was 1,564 kg, flight weight — 4121 kg.
Order of the MAP number 222 of 08/18/1946 to increase the duration of the flight-270 Dushkin chief designer and head of the SRI-1 undertook to create, make and submit to the state bench. tests of liquid rocket slider RD-2MZV resource having one o'clock in November 1946. In a couple of OKB-155 engines that resource must be put to 01.07. 1946.
I-270 in design is a cantilever all-metal midwing. Semi-monocoque fuselage had a circular slot number 10 on frames for easy access to the power plant. Reinforced end frame was used for fixing the rear spar of the keel and liquid rocket engine (4 points). Cut-made inside the central part of the fuselage, was designed to fit the wing, is a one-piece chetyrehlonzheronny caisson with thick metal cladding panels. Mechanization — slotted flaps and ailerons of the "Fries". The angle of the cross-wing V — 2 degrees, the angle of the 1 degree.
As shown by tests of scale models in a high tunnel and flight tests in part I-300 (F) and I-250 (H), the designers planned to have a 12% straight-wing and selected profiles (TsAGI TsAGI and-1S1012-12145) satisfactory torque properties of the composition "fuselage-wing" to the number of M = 0.85-0.9. In addition to saving satisfactory torque characteristics reducing impact on the horizontal tail wing it raised 1.2 MAR relative to the wing, and tail carried a T-shaped. Sweep of the horizontal and vertical tail was 20 degrees. The relative thickness of the profile of the horizontal tail TSAGI-08045 — 8 percent.
Straight wing in the upcoming meant to change swept. Explanatory note to the preliminary design, it was noted: "… How will purge the opportunity to start the development of the swept wing, the airplane will do so on the swept that with increased traction motor Dushkin will increase speed of the aircraft in a horizontal plane, and even eclipse the 1,100 kilometers per hour. " The plans of the NII-1 to 1946 provided for the crossing of the RD-2MZV to pull two thousand pounds.
Tricycle landing gear, a front support. Amortization of air-oil, gear actuation was carried out with the help of compressed air. Track main landing was very narrow (1.60 meters), and was removed in the central part of the fuselage — spec. niche under the wing between the frames number number 10, 14. Under the pressurized cabin housed niche bow rack, and two NS-23 cannon and ammunition. Dining car produced specials. Blower "198a". To protect the pilot serves as the front armored plate width of 8 mm and 15-mm armored glass. To rescue the pilot in an emergency plan to put the car on the ejection seat.
Special equipment consisted of: red dot scope CRP-1, radiopolukompasa RPKO-10 radio RCI-6 Identification System "friend or foe" and the oxygen device KP-14.
The power plant — two-chamber liquid-fuel rocket engine RD-2MZV. Both the combustion chamber arranged above one another in the aft fuselage. Liquid rocket slider worked consistency of 96% percent nitric acid and kerosene, and a turbopump unit, which supplies the fuel and oxidant into the combustion chamber working at 80% hydrogen peroxide. The supplies of fuel component — 2120 kg. In fuel system included three types of tanks 4 acid (1620 kg), 1 kerosene (440 kg) 7 for hydrogen peroxide.
On-board electrical system consisted of: generator that runs from the turbopump assembly liquid rocket motor and generator GS-1000, located in the forward fuselage having a drive from a small two-bladed rotor and rotating from the incoming air stream.
In the manufacture of fighter I-270 also increased emphasis on protecting the structure from the damaging effects of nitric acid fumes. For this purpose we developed acid-resistant fittings and special anti-acid coating. Depending on the degree of the damaging effects of HNO3 car was broken into four zones: the first — which has at normal temperatures the greatest degree of anger, the second zone — too, but at elevated temperatures (110 to 150 degrees), the third area — the smallest the degree of anger, the fourth area — the rest of the design, which is exposed to a brutal environment.
All aluminum parts are located in areas of brutal, apply several layers of Aviation Materials developed in the protective coating. The number of layers depending on the location of parts came to 9. A protective coating made prior to installation plane. The design of the entire machine after assembly further coated with paraffin and ceresin paste.
To monitor the condition of the structure, gain access to the aircraft installed so called "witnesses", represent three records (one iron and two aluminum) with a different cover. Galvanized iron plate, aluminum anodnooksidirovali one and the other — coated antacid solid composition.
In accordance with the schedule of the design and manufacture of the product "F" approved May 15, the roll-out of the airfield first instance planned for 20.10.1946. But due to repeated adaptations aircraft project, working drawings only managed to finish on October 2. By this time the completed assembly of the head of the fuselage and a pressurized cabin, set up for testing in the thermal vacuum chamber, and started static tests tail.
The pace of work declined because the main workers and craftsmen were sent to the aircraft factory number 1 after Stalin (Kuibyshev) to assist in the construction of a series of head-I-300. Because the deadline to finish the assembly and transmission of the aircraft for flight tests failed. In addition, businesses fifth and eighth State MAP supply the necessary equipment was broken.
3-year-old copies of the fighter-interceptor-270 was built two. First received index "F-1", the assembly line rolled out December 28, 1946. Responsible for carrying out industrial tests have been appointed chief engineer Turchkov AF and test pilot VN Yuganov Delivery of the flight has been delayed motor. The aircraft mockup installed engine, acquired on October 21, which is not allowed to start the real flight tests. Since there was no conditioned engine tests were divided into two steps.
At first, "engineless" step interceptor shall be towed behind bombers Tu-2. To conduct these tests, the aircraft facilitated the removal of all unnecessary goods: fuel tanks, engine mock-up, weapons and power wiring motor. By towing tests "F-1" began February 3, 1947. Yuganov this day completed the first 13-minute flight. Aircraft-towing TU-2 number 1041 ran the test pilot Shelest II
Before Gliding tests were carried out preparatory training. 11 and 13 January, ground-towing to the most experienced cutaway interceptor speed and flying up to a height of about 2-meters. February 3 Yuganova was made a training flight in the Yak-9, towed by the Tu-2 number 1041 as a glider. To simulate the characteristics of the transverse and longitudinal resistance, similar to the calculated characteristics of the new aircraft, Yakovlevskaya car was loaded with lead ingots.
Uncoupling of I-270 and Tu-2 bomber in flight on a leash occurred after a set of 5000-7000 m Then the prototype commit solo flight and landing following a glider. At the planning got a small airspeed coast 220 km / h and the highest 600 km / h The first step of the test, allowed to find properties agility and endurance aircraft maneuvering properties and remove the balancing curves, was completed on June 25. Produced eleven towing operations with cutaway.
On subsequent instance (ind F-2) May 8, 1947 established the flight engine RD-2MZV. It is possible to start the second step of the test. Lead engineer on the engine was appointed Kovunovskogo NI, and a mechanic — Lukashev AI July 16 at the end of working off the engine on the ground exploded a small camera, which resulted in damage to the aft fuselage. The car went for repairs, ending August 2. A test pilot Lt. Col. AK Pakhomov, coaxed the tests as Yuganov fell ill, performed on "F-2" on Aug. 26 and two taxiing podlet.
First independent flight fighter interceptor-270 (ind F-2) was held on 2 September 1947. Rise at the working engine was the usual aircraft was recruited three thousand meters altitude Then the pilot, in accordance with the flight plan, and began to plan for the landing, but due to inaccurate calculations, with a huge "blunder" seat restraints, performed outside an airport landing . 7-minute first flight was the last. Was smashed nose of the aircraft fuselage, but the pilot did not get injuries. The car did not recover.
Meanwhile, on the F-1 engine installed instead of mock-conditioned, and August 14, the plane entered the LII naletnyh for testing. September 29 Yuganov performed taxiing, and on 4 October the aircraft was flown.
During the flight, along with spices LII measured the line of motion, rate of climb and speed interceptor-270. To register characteristics performed photographing with 2 kinoteodolitami of "Ascanius," which placed apart at a distance of 1737 m was shooting speed of 4 frames per sec., From start to start off the engine.
During his return to the airfield to release it did not work. All samples pilot to let him have not met with success. Yuganov decided to put the car on the fuselage. By choosing not a bad place, professionally landed on a rather limited area, this car received minor injuries. Flight duration — 12 min.
After processing the acquired disk imaging testers received the following data: the time and length of the runway were 20 seconds and 697 meters, the lift-off speed was 233 km / h, the engine went off at an altitude of 4450 m over 130.5 sec., The speed at an altitude of 2900 m was adjusted to 615 miles per hour.
The accuracy of the results acquired given the opportunity to advise the use of fotokinoteodolitov in flight testing to determine the vertical and horizontal projections of the line of motion, rate of climb and speed, especially in the transient regime of flight.
Testers continued to pursue woes. So, for example, on October 21, after repairs on the ground when you run the motor blew a great camera, resulting in a liquid rocket engine nozzle is pulled out. Repairs were completed on November 20.
I-270 (F-1) for the flight was quite prepared in January 1948. But subsequent tests were suspended. It was found that the operation in the winter criteria of acid liquid rocket engine is not fulfilled.
After each flight, it was necessary to flush the system with water, and create these works within the airfield criteria in the cold problem. Also, for high-altitude flight was unsuitable weather. Mikoyan, agreeing with the question Dushkin, gave instructions not to carry out flights and March 1948 to preserve the aircraft.
The military provided work on the fighter-270 close attention. Since mid-1946, the order of the latest technology, observation of con
struction, as subsequent tests of the prototype was engaged once again made Aviation Technical Committee (ATC Air Force). According to the results of tests of the fighter-interceptor-270 in March 1948, experts at the agency made the following conclusions:
— iron parts under the influence of acid vapors very corrode, even in spite of the application of the safety cover;
— in-flight engine restart is not allowed, because of the risk of explosion due to the likelihood of accumulation in the cell motor acid;
— calculation of a plane landing without engine running is difficult, due to its off the air because of the non-long-time work;
— used to neutralize the acid water, which is not acceptable for use with the aircraft engine in the winter;
— need serious follow the operating instructions of acid tanks because of the strong effects of acid vapors acid tanks (acid tank rupture occurred during his inspection control under pressure after a two-month operation by air);
— by annotations after 2 months operation tank on the aircraft under its acid fumes should be removed for inspection of hard, since acid tank has a huge storage capacity, works on his substitution on this aircraft designs were very labor-intensive;
— tehsostava outfit used in the operation is cumbersome and awkward (jacket and pants — rubberized), from the effects of acid wear out quickly (rubber gloves, boots).
The military was busy waiting position. On the one hand, the military did not want to get a similar interceptor into service, on the other hand believed that the MAP to bring RD-2MZV to the highest degree of safety and reliability, and to continue the trial operation of the rocket plane to experience congestion.
After the reopening of the aircraft 31 May 1948 test pilot Pakhomov AK made a 13-minute test flight, held without incident. But the Ministry of the aviation industry did not want to "accumulate operating experience" as a dangerous technology, in connection with which plane in the air is not ascended. Issue of non-governmental decree of 02.26.1946 on mutual consent is no longer open a discussion.
Flight and technical properties of the fighter-interceptor-270:
Wingspan — 7.75 m;
Length — 8.77 m;
Height — 2.80 m;
Wing area — 12.00 m2;
Empty weight — 1893 kg;
The biggest take-off weight — 4120 kg;
Mass of fuel — 2120 kg;
Motor type — liquid-propellant rocket engine RD-2M-3V;
Rod — 1450 kg;
The highest speed at the ground — 1000 km / h;
The highest speed at altitude — 936 km / h;
Duration of flight at an altitude of 5 km on the small chamber — 6.72 min;
Duration of flight at an altitude of 15 km at maximum thrust — 4.15 min;
The highest rate of climb — 4220 m / s;
Service ceiling — 17 km;
The crew — 1 person;
Armament — two guns NS-23 23 mm;
Ammunition — 80 rounds.