Gruschin Sch-Tandem
| Gruschin Sch-Tandem | |
|---|---|
| Type: | Fighter bomb and ground attack aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
December 5, 1938 |
| Commissioning: |
- |
| Production time: |
1938 |
| Number of pieces: |
1 |
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The Gruschin Sch-Tandem ( Russian Грушин Ш-Тандем ) was a Soviet experimental aircraft of the late 1930s. The name Sch-Tandem resulted from the greatly enlarged horizontal stabilizer , which served as a smaller second wing , so that both pairs of wings together formed a tandem wing . Due to the poor flight characteristics, only a prototype was built.
development
In the course of a government decree issued on March 22, 1938 for the expansion of attack, reconnaissance, training and rescue aviation forces, engineer Pyotr Grushin , who works at the Moscow State Aviation Institute (MAI), was commissioned to develop an attack aircraft in tandem construction. The reason for the decision in favor of this unconventional design was the positive experience that Gruschin was able to gain with his light aircraft Oktyabrjonok (Октябрёнок, Oktoberkind), which had been designed two years earlier and which took off on October 23, 1936 with Alexander Zhukov for its first flight . After the tests carried out by the MAI, the aircraft had successfully passed a series of tests at the Research Institute of the Air Force (NII WWS), which led to considerations for a reconnaissance and bombing aircraft with a similar concept. The decree envisaged the M-88 engine by Sergei Tumanski , which was under development at the time , with which a maximum speed of 500 to 530 km / h and a range of 950 km should be achieved.
As with the Oktyabrjonok, construction and construction were carried out in the MAI's training workshops and completed in June 1938. However, as the development of the M-88 engine was delayed, a less powerful Tumanski M-87 had to be used, which in turn led to the required speed and range being reduced to 488 km / h and 700 km respectively. After this delay, the Sch-Tandem was handed over to the NII WWS for testing on November 16, 1938, which test pilot Pyotr Stefanowski took over. The taxiing and take-off tests carried out from November 23rd onwards revealed the first problems with the controllability, as the rotating machine-gun turret arranged in the rear had an unfavorable effect on the directional stability, which led to the aircraft breaking away. The ground tests were finished on December 3rd and two days later Stefanowski carried out the first flight, during which a speed of 250 km / h could not be exceeded due to the detected instability. Stefanowski noticed that the rudder mounted in two end disks on both sides under the horizontal stabilizer had little effect, and that the aircraft had a tendency to turn around the vertical axis . A total of more than 20 defects were found, which it was hoped to remedy by reinforcing the wings and the wing center section and installing a new M-87. In the meantime winter had come, so a ski undercarriage was installed. After being converted in this way, the test was to be continued on February 22, 1939, but it turned out that the rudder had almost no effect when steering on the ground. As a result, the Sch-Tandem took off on another flight on February 26th. Again, the stability was criticized and could not be improved even with repeated changes to the vertical stabilizer. Further testing, which in turn also included an interim use of a skid running gear, was stopped for the time being in May of that year due to the non-remediable defects and Stefanowski left the program.
At the beginning of July 1939, Wladimir Datzko carried out the tests, which this time were affected by chassis problems, until August, when a final redesign took place. As a result of the measures, among other things the tail tower was expanded and replaced by a cover, the appearance of the aircraft changed significantly, which in some publications led to suspicions about the existence of a second prototype; the use of a M-105 - V-type engine is occasionally found. On September 9, 1939, the test program was officially ended after 54 flights with 19.10 hours of flight time. The final state report of October 19, 1939 then finally certified the Sch-Tandem that it was unsuitable for a combat aircraft.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 (pilot, gunner) |
| span | 9.80 m |
| length | 8.05 m |
| height | 3.55 m |
| Wing area | 17.7 m² (wing) 8.0 m² (tail unit) |
| Preparation mass | 2336 kg |
| Payload | 814 kg |
| Takeoff mass | 3150 kg |
| drive | an air-cooled 14-cylinder double radial engine Tumanski M-87A with 960 PS (706 kW) |
| Top speed | 361 km / h near the ground 414 km / h at 3000 m altitude 444 km / h at 5600 m altitude |
| Landing speed | ≈ 145 km / h |
| Take-off run | 400 m |
| Armament (projected) | four rigid 7.62 mm MG SchKAS in the wings one movable 7.62 mm MG SchKAS in the rear stand 200 kg bomb load |
literature
- Andrej Awerin: Gruschin's hapless tandem. In: Aviation Classics. No. 05/2018, Motor Presse, Stuttgart, pp. 28–33.
- Manfred Jurleit: Gruschin "Sch-Tandem" (MAI). In: Fliegerrevue. No. 11/1972, Military Publishing House of the GDR, Berlin, p. 481.
Web links
- Грушин Ш-Тандем. Retrieved October 11, 2019 (Russian).