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Sh-Tandem
Light Attack Aircraft
Grushin

Sh-Tandem is an experienced two-seater light attack aircraft of the original tandem scheme of Pyotr Dmitrievich Grushin, the future creator of the S-300 missile system. When choosing a scheme, it was meant that it would allow, in the presence of an inevitable mass separation along the length of the aircraft, to obtain fairly good characteristics of the longitudinal stability of the aircraft.

The admissibility of using more rear alignments allowed Grushin to place a machine-gun mount directly in the tail section of the aircraft, which, in combination with the two-fin tail, provided large firing angles. The tandem scheme made it possible to reduce the diameter of the circle into which the contour of the aircraft fit in the plan, which contributed to the lesser attackability of the attack aircraft. At the same time, the distribution of payload and armor was simplified.

Small wingspan hindered the use of wood as the main structural material to a lesser extent. The main, front wing, was low-lying and the landing gear struts and wheels were retracted into it. The crutch wheel is non-retractable. The hind wing, which had an upper location, with an area equal to 45% of the main wing, also served as a horizontal tail. Ailerons were on both wings, and on the rear wing they simultaneously served as elevators. The vertical tail was made in the form of washers attached to the ends of the horizontal tail.

Initially, the aircraft was planned to be equipped with an air-cooled M-88 engine. But since it was not ready, the M-87 was put on the Sh-Tandem, and then the M-87A.


IDS - Istrebitel' dal'nego soprovozhdeniya - Long-range escort fighter

Sh-Tandem
Crew 2
Dimensions
Wing span, m 11.00
Wing area, m² 30.40
Length, m 8.50
Powerplant
1 × PE M-87, power, h.p. 1 × 930
Weight, kg:
Empty
Loaded weight 2,560
Performance
Maximum speed at the ground, km / h 406
Maximum speed at altitude, km / h 488
Ceiling, m
Armament
5 × 7.62 mm ShKAS machine gun, bombs on the suspension, kg 200

The fuselage, center section and main wing were manufactured by a team of MAI training and production workshops of 18 people in just 45 days. By January 8, 1939, the aircraft in a single-seat version and without weapons passed preliminary flight tests with the M-87 engine. A fairly high maximum flight speed was reached, which was quite consistent with the TTT for the aircraft. At the ground, it was 406 km / h, at an altitude of 4250 m - 488 km / h. According to the test results of P.D. Grushin was recommended to move the navigator's cabin a few more back on a two-seater version and equip it with an MV-5 rifle mount.

In September-October 1939, a two-seater version of the Sh-Tandem with the M-87A engine (rated power at an altitude of 4700 m - 950 hp) and with a variable pitch propeller VISH-3 underwent joint (factory and state) tests ... The test report was approved on October 10th. The navigator's cockpit was shifted back, and a shielded MV-3 ​​turret was installed. The armament of the attack aircraft was standard for light attack aircraft of that time: 4 wing-mounted ShKAS machine guns with 2400 rounds of ammunition, one ShKAS machine gun on a turret (700 rounds of ammunition) and 200 kg of bombs. During the tests, 51 flights were performed with a total flight time of 18 hours 38 minutes. With a flight weight of 2800 kg, the attack aircraft had a maximum speed at the ground of 361 km / h, and at an altitude of 5600 m - 444 km / h. Landing speed without flaps is 140-145 km / h. Takeoff run - 400 m, run - 480 m. The flights were carried out with a CAP of 34-44% of the MAR. It was noted that the aircraft is very easy to operate.

The plane did not pass the state tests due to the discrepancy between the flight data of the TTT, insufficient directional stability ("when the speed increases, the plane scours"), a cramped navigator's cabin, an unsuccessful landing gear, and insufficient strength of the front wing. The takeoff of the plane was difficult. Longitudinal stability reserves were insufficient. The plane reacted sluggishly to the rudders. It was believed that the excess of the rear wing over the front was not a very good decision. The armament was also undelivered. Since the MV-3 ​​turret "ate" 34 km / h of flight speed, it was proposed to make the rear gun mount conical, allowing the machine gun to move in a plane passing through the longitudinal axis of the mount and rotate this plane around the axis by 360 °. At the same time, it was noted that the Sh-Tandem combat scheme is of interest. It was proposed to transfer the plane to TsAGI, bring it and again submit it for testing.

A backup for the Sh-Tandem aircraft was built. On the second copy, the rear wing was lowered down. When the degree of readiness of the understudy was 65-70%, all work was stopped. The unusual layout and rather weak armament did their job. In May 1939, the NKAP decided to stop all work on the Sh-Tandem.

Photo Description

Drawing Sh-Tandem

BB-MAI

Short-Range Bomber

The next aircraft of P.D. Grushin was created at the MAI - the attack aircraft and the short-range bomber "BB-MAI". The machine is somewhat smaller, of the classical scheme, but with an M-105 engine of greater power (1050 hp). The aircraft was designed in 1938-1939. as an attack aircraft and as a close bomber. Wing "BB-MAI" - two-spar, of three C-shaped sections, molded from bakelite plywood. When the sections were inserted into each other, their leading edge formed the wall of the spar, and the shelves became the skin of the wing. The sections and the wing were assembled using VIAM B-3 glue, and when they were assembled, a monolithic caisson was obtained. The thickness of the skin on the toe of the wing is 5 mm, in the tail section up to 3 mm, and between the walls of the spar - up to 25 mm. The fuselage is a monocoque type made of bakelite plywood on the same glue. The surface of the BB-MAI, like the previous aircraft, was polished to a shine.

VIAM specialists helped master the production technology of bakelite plywood structures. The machine was equipped with a retractable turret, a CIAM supercharger was installed on the engine, which was powered by exhaust gases. For the first time in the USSR, a tricycle landing gear with a nose wheel was installed on the BB-MAI. Behind the nose wheel was a radiator. The wheels were retracted into the wing towards the fuselage with the wheels turning relative to the racks. Wing - small: area 15.2 m², narrowing 3.5. With a takeoff weight of about 3500 kg and a small wing area, the specific wing load is about 210 kg / m². (Such a large load is adopted in order to increase the maximum flight speed.) Automatic slats were installed on the wing.

The construction of the aircraft, which began in 1939, was completed at the end of 1940. Lead engineer for the construction of the machine A. A. Lebedinsky, lead engineer for testing A. A. Manucharov. Test pilot - MAI graduate A. N. Grinchik. The protracted construction led to the fact that its first flight took place only in December 1940, when the Air Force lost interest in this aircraft.

BB-MAI Specification
Crew 2
Dimensions
Wing area, m 10.00
Wing span, m² 16.80
Length, m 9.60
Powerplant
1 × PE M-105, power, hp. 1 × 1050
Weight, kg:
Empty 2,965
Loaded weight 3,490
Performance
Maximum speed, km/h 550
Service ceiling, m 9,000
Service range, km 500
Photo Description

Drawing BB-MAI Grushin

Gr-1 (IDS)

Heavy Fighter

One of the least known heavy fighters created in our country on the eve of the war was the so-called long-range escort fighter IDS, P.D. Grushin.

In 1940, Grushin was transferred to the position of chief designer of the Design Bureau of the Kharkov Aviation Plant No. 135.

The main task assigned to the designer was the creation of a heavy long-range escort fighter as part of the overall program for the development of an aircraft of this type.

Work on the project went pretty quickly. In December 1940, the still unbuilt aircraft was given the name Gr-1, that is, Grushin-first.

Unlike the OKO-6 heavy twin-engine fighter built here, Grushin's IDS was designed for two AM-37 liquid-cooled engines designed by A.A. Mikulin with a capacity of 1200 hp. According to its aerodynamic design, the aircraft quite strongly resembled the well-known German multi-role fighter Messerschmitt Bf .110 at that time and had overall dimensions close to it. Even outwardly, especially when viewed in plan, both cars were very similar. True, unlike the Messerschmitt, the Gr-1 was single-seat, and the radiators of the engine cooling system were located under the wing center section and were made retractable. The exhaust manifolds of the engines were brought to the upper surface of the wing, as was done on the Mikoyan-Gurevich DIS and Polikarpov TIS. The cockpit was armored. It is interesting to note that this factor was taken as the basis for determining the number of crew - one pilot or two. In terms of weight, the double version of the cabin with equipment for the gunner-radio operator was by no means heavier than the armored box, welded from steel sheets and completely protecting the pilot. Nevertheless, Grushin gave his weightmen the task of analyzing both options, so they ended up with a fully armored cabin for a single-seat variant that would be 18 kg lighter. That's how this plane came out single. Perhaps this decision was somewhat hasty, since the need for a second crew member on machines of this class was subsequently confirmed by the war.

It should be noted that the armament of the IDF was extremely powerful and was in no way inferior to its main enemy - the Bf.110. Two ShKAS machine guns were located in the forward fuselage, and above them were two 20-mm ShVAK cannons. Two more ShKASs were installed in the wing fairings, firing outside the propeller sweep area. All machine guns had 1250 rounds of ammunition for each barrel. The ammunition load of the guns included 300 shells. Another lower ventral mount was envisaged with two 37-mm guns with 200 rounds of ammunition per gun.

Under the wing of the aircraft, it was possible to install four beam holders for hanging eight 100-kg bombs or four RS-82 or PC-132 rocket projectiles. In addition, instead of the ventral cannon container, up to 500 kg of bombs could be placed on the internal suspension.

Despite the apparent similarity with the German Messerschmitt Bf.110, the Grushinsky IDS had a design that was fundamentally different from it. The wing spars had a box-shaped cross section. Their walls and shelves were made of tapered steel strips welded into a closed loop. Spars connectors had an original design with transverse combs.

The aircraft was designed and built in just nine months. Static strength tests took several days and by the early spring of 1941 the aircraft was put into flight. After lengthy refinements and the elimination of a large number of minor problems, they remembered that the aircraft did not undergo full-scale purges at TsAGI. The car had to be dismantled and sent to Moscow. After this stage of testing, the aircraft was again transported to the plant number 135 to eliminate the comments. The date of the first flight was approaching, but then the war began. When trying to evacuate the plant to the East, on the way from Kharkov, the echelon came under bombardment. At the same time, the aircraft was badly damaged, all design documentation burned down, and work on the aircraft was no longer resumed.

Sam P.D. Grushin was sent to work at plant number 21, where he held the position of chief engineer, and then deputy chief designer S.A. Lavochkin.

Gr-1 Specification
Crew 1
Dimensions
РWing span, m 16.80
Wing area, m² 42.00
Length, m 11.60
Height, m 3.88
Powerplant
2 × PE AM-37, power hp. 1 × 1250
Weight, kg:
Empty 5,420
Loaded weight 7,650
Performance
Maximum speed over ground, km/h 448
Maximum speed at altitude, km/h 650
Service ceiling, m 11,700
Service range, km 1,380
Armament
4 × 7.62 mm ShKAS machine guns (1250 rounds each)
2 × two 20 mm ShVAK cannons (300 rounds each)

Petr Dmitrievich Grushin began working in the field of aircraft construction while still a student at the Moscow Aviation Institute with the construction of the Stal aircraft at the MAI. Having received a diploma in mechanical engineering in aircraft construction, Grushin was left at the institute and worked at the department 101 (Aircraft construction), and then became the chief designer of the MAI Design Bureau. Working in this position from 1934 to 1940, he built a number of aircraft, among which the BB-MAI light bomber was the most famous.

After the war, he worked on the creation of anti-aircraft missiles, including the S-300 anti-aircraft complex, and was subsequently awarded the title twice Hero of Socialist Labor.

Photo Description

Drawing Gr-1 (IDS) Grushin

Bibliography

  • The History of Designs of Planes in USSR 1938-1950 /Vadim Shavrov/
  • Red Army stormtroopers / Vladimir Perov, Oleg Rastrenin /
  • Transformer engineer Grushin / Andrey Averin /
  • Long-Range Escort Fighter Gr-1 / Ivnamin Sultanov. A&K/