Heinkel HD 37
The Heinkel HD 37 was a German fighter aircraft that was designed by Ernst Heinkel to the end of the 1920s for the Soviet Air Force. In the Soviet Union it was built under the name I-7 under license. HD stands (Russian for fighter aircraft ) for " Heinkel Biplane " I for " Istrebitel ".
History
Under the impression of from 1926 tested at the secret testing facility in the Reichswehr Lipetsk Hunter HD 17, the Soviet military leadership Heinkel gave the order to create a succession pattern with a BMW -VI - drive. Intended were two specimens should be tested extensively. With a positive cutting off the purchase of the manufacturing license was provided. The construction of the two test patterns began in late 1927 in violation of the arms limitations of the Versailles Treaty and was followed by Soviet specialists. The first flight took place in April 1928 by the Head of the DVL Joachim von Koppen on the grounds of the Heinkel works in Warnemünde. Subsequent tests were carried out by the Swedish test pilots Nils Söderberg, who, among other things, the succession pattern tested for Heinkel HD 43. The HD 37 had an impressive for its time rate of climb. However, the high angle of attack during takeoff and landing proved to be disadvantageous.
In April, the two HD were taken 37 from a Soviet commission and transferred to the USSR. In July, there began the test flights of the first machine with the pilots I. F. Kozlov and W. O. Pissarenko. In Trudel Try the aircraft fell on July 20, out of control and crashed, Pissarenko could jump with a parachute. Heinkel then sent to the factory drivers from Prodzynski to investigate the incident. It turned out that some passages of the German Operations Manual had not been translated into the Russian language. From Prodzynski began on 14 August, the testing of the second HD 37 and brought them without further incident to an end.
From the Soviet side some suggestions for changes to improve the spin properties were submitted in response to the incident. Therefore, the Heinkel HD 43 developed with modified airfoil, control and suspension and wing area. It also made two copies, which went into the testing at the end of 1929. Contrary to all predictions had the HD 43 is worse flying characteristics than its predecessor, and so ultimately the HD 37 has been approved for series production. Heinkel received 150,000 Reichsmarks for the sale of the license.
The production began in 1931 under the name I-7 with the BMW VI engine license M- 17 in the Moscow plant # 1, after the work had been No. 39 refused. During production, tailored changes were made to the local possibilities. This applied, for example, the cooler assembly and the bonnet. Since the domestic industry was not able to make the necessary framework for the short - molybdenum steel tubes, they had to be imported. The license aircraft had over the built by Heinkel poorer performance. This mainly concerned the speed and climb performance. Since about the same time produced local Polikarpov I-5 reached approximately the same data, it was finally. The standard fighter of WWS in the first half of the 1930s The production of the I- 7 was discontinued after only 131 copies in 1934, which were also retired after a very short time from the first line.
Technical structure
The HD 37/I-7 was a tense biplane. The fuselage consisted of a molybdenum steel pipe scaffold and was planked from bow to cockpit with aluminum; behind it was covered with fabric and partially covered with plywood. The wings of different span consisted of a wooden structure with fabric covering and were connected by N- struts with each other and with the fuselage. Due to the cockpit along narrow " camel" hull and the low rate upper wing, the pilot had a very good view. The tail unit was conventional and braced with I- stems and braced. The main wheels of the chassis were rigid and had no connection with each axis. At the rear, there was a tail skid. As with most Soviet aircraft of the time, there was also the I-7 a ski landing gear for the winter.
Technical data of HD 37
The values given in parentheses refer to the license model I-7