Tupolev ANT-25
| Tupolev ANT-25 (RD) | |
|---|---|
|
|
| Type: | Long-haul aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
June 22, 1933 |
| Commissioning: |
1934 |
| Production time: |
approx. 1934 to 1937 |
| Number of pieces: |
24 |
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The Tupolev ANT-25 ( Russian Туполев АНТ-25 , also: RD , РД) is a Soviet aircraft . It became famous for a long-distance record flight from Moscow to California in 1937.
history
In autumn 1931, the M-34 engine designed by Alexander Mikulin was ready for series production. Since it was relatively economical in terms of fuel consumption, the Revolutionary War Council (RWS) decided in the same year to construct an aircraft for long-haul flights and to equip it with this propulsion system in order to carry out record flights and thus help the Soviet aviation industry to gain international recognition. The RWS had been founded shortly before to promote the realization of such projects, chaired by Klim Voroshilov . In a letter, the Commander in Chief of the Air Force Yakov Alksnis and the aircraft designer and head of the ZAGI Andrei Tupolev suggested that the council take over the planning of such a flight. Then in 1932 the development contract for an aircraft called RD - Russian for long-distance record - was awarded to the design department of Pavel Sukhoi within the ZAGI. Suchoi planned a single - engine low- wing aircraft made of duralumin with a large wingspan and conventional tail unit. Compared to a fuselage length of around 14 meters, the wings, which Vladimir Petlyakov and Viktor Belyayev were responsible for, had a wingspan of over 34 meters. They also housed the 10,230 liter fuel tanks. The wheels of the main landing gear retracted halfway back into the wings. The official designation ANT-25 - Tupolev's initials as head of the design department - was only assigned to the aircraft after the first records flown. In the meantime, when Tupolev was arrested in October 1937 in the course of the Great Terror and it was forbidden to use the abbreviation ANT for his constructions, it was also called ZAGI-25 .
Two aircraft were commissioned under the designations RD-1 and RD-2 . The first flight of the RD-1 was carried out by Michael Gromow on June 22, 1933 from the Schcholkowo airfield . Because of the long taxiway, the runway had to be extended. During the tests, however, the RD-1 equipped with a standard M-17 engine only achieved a range of 6950 kilometers. Even the installation of a compressor did not result in any significant increase in performance. Therefore the RD-2 was aerodynamically improved and got an M-34R with propeller gear (R for reducer, gear). Equipped in this way, it flew for the first time on September 8, 1933 and achieved a range of 10,800 kilometers with a take-off mass of 10,000 kilograms during testing. However, at least 13,000 km were required and so the aircraft was revised again. On June 24, 1934, the first long flight took place on the Moscow – Ryazan – Tula – Moscow route with crew members Michael Gromow, Alexander Filin and Iwan Spirin . A second flight followed two months later, but ended after 34 hours of flight time due to problems with the engine in Ryazan on 23 August. Alexander Filin was arrested years later on May 23, 1941 and died in prison under unknown circumstances.
On September 12, 1934, the RD-2 took off from Shcholkowo on a flight of 75 hours and 2 minutes and had landed in Kharkov with 12,411 kilometers, her first world record on a closed route. The pilot Mikhail Gromov was then awarded the title Hero of the Soviet Union . As a result, plans began for an international record flight. It was finally decided to take a route via the North Pole to the USA. The experienced polar pilots Sigismund Levanewski , Georgi Baidukow and the navigator Viktor Levtschenko were therefore selected as crew . Levanewski - one of the first heroes of the Soviet Union and made famous for his help in rescuing the Cheliuskin crew - had previously asked Joseph Stalin in a letter in the spring of 1935 to entrust it with the execution. For the flight, the RD-2 was equipped with heating, ventilation and a metal propeller. The start took place on August 3, 1935. Levanewski broke off this flight over the Barents Sea, despite Baidukov's violent contradiction, because he mistakenly considered the overfilled and thus leaking oil tank to be an average. When evaluating the flight Levanewski attacked the designer Tupolev violently and declared that he would no longer want to fly in any of his aircraft. Baidukov therefore formed a new team with Valery Chkalov as commandant and Alexander Belyakov . Two years later, Levanewski and Levchenko, who again belonged to the crew, disappeared over the North Pole on August 12, 1937 in a second record attempt with a four-engine DB-A bomber . The crew is still considered lost today.
From September 1935, another flight to the USA was considered. In addition, two more RD were commissioned, which were built in Voronezh Plant No. 18. Before that, the Chkalov / Baidukow / Belyakov crew succeeded on July 20, 1936, in increasing the record for continuous flight to 56 hours and 20 minutes when they covered the distance from Moscow to the island of Udd near Kamchatka (9,374 km) without stopping. For this flight, all three pilots were named Heroes of the Soviet Union. On August 24, 1936, Chkalov presented the ANT-25 to the public at the Tushino Air Parade. He then flew the plane to the Paris Aérosalon in November of the same year . Michael Gromow, who had also flown an ANT-35 to the air show, met with Chkalov there and agreed with him to fly over the North Pole to the USA with two RDs. For an unexplained reason, however, shortly before the start of the company, the engine from Gromov's aircraft was removed and installed in the Chkalov ANT-25, as its M-34 was considered to be less reliable.
Only Chkalov's crew was able to start a flight over the North Pole on June 18, 1937 with the USSR-N025 . For this purpose, a concrete ramp was built to help the aircraft loaded to the limit of its carrying capacity. Due to the prevailing bad weather, the RD mostly flew blind at an altitude of 4,000 meters. On June 20, after 9,130 kilometers and 63 hours / 16 minutes of flight time, it landed in Portland / Oregon at 7:20 p.m. Moscow time. The FAI recognized the record as the direct flight route between start and destination (8,504 km). The crew stayed in the USA for about a month and left the country on July 14 with the passenger ship Normandie from New York for Europe. On July 12th, Mikhail Gromov was ready to take off with another RD ( URSS-N025-1 ). The crew had previously decided to refuel with another type of gasoline instead of the special fuel in order to be able to fly higher and therefore more fuel-efficient and ultimately further. The flight went 10,148 kilometers from Moscow via Siberia , the North Pole , Vancouver and ended at San Jacinto in California on the Mexican border because the Mexican authorities did not issue an entry permit. Gromov's plane was in the air for 62 hours / 17 minutes. This record lasted until 1946. The RD was then returned by sea and took part in the annual Tushino Air Parade on August 18th. Chkalov's plane flew one last time to the United States in December 1939, where it was presented at the World's Fair, and returned by ship in January 1941.
From the RD there was also the long-range bomber variant DB-1 (also: ANT-36 or RDD ). 50 units were ordered from the WWS, but only about 13 to 20 units were built in the Voronezh factory because they did not meet the expectations placed on them. The aircraft were, unless they were used for tests with pressurized cabins to reach greater heights, mothballed in 1937 and later scrapped.
Whereabouts
In the Chkalov Museum in Chkalovsk and in the Air Force Museum in Monino, an ANT-25 of the record version can be viewed. The Monino copy is a replica made in 1989 by OKB Tupolew. The Chkalovsk ANT-25 also seems to be a replica. A third, original RD was destroyed in attempted shelling. No copy of the DB-1 bomber has survived.
Further developments for height tests
Four aircraft of the bomber version DB-1 were handed over to the office for special constructions and converted there under the designations BOK-1, BOK-7, BOK-11 and BOK-15 for height tests.
The BOK-1 (also: SS for Stratosferni Samoljot, Stratosphärenflugzeug) received a slightly enlarged wingspan and a non-retractable main landing gear with only one wheel per side (the ANT-25 had double tires). In autumn 1936 she reached an altitude of 10,700 meters in 38 minutes with an M-34RN engine. Lightened and equipped with an M-34RNB engine and two TK turbochargers developed by W. I. Dmitrijewski, it is said to have climbed to 14,100 meters in the spring of 1937.
The BOK-7 received an M-34FRN engine and was equipped with a hermetically sealed GK (Germeticheskaya Kabina) cabin designed by Alexei Shcherbakov for a circumnavigation of the world. The pressurized cabin - one of the first in the Soviet Union - had previously been tested in the BOK-1 by Pyotr Stefanowski and I. F. Petrow. It consisted of a cylinder with a wall thickness of 1.8–2.0 mm and a volume of 2 m³. The two-man crew, consisting of the pilot and navigator, who simultaneously acted as radio operator and observer, sat one behind the other. The first flight of the BOK-7, also known as the K-17 (K stands for Krugoswetnoje puteschestwije, circumnavigation of the world), with its wingspan reduced to its original length, also took place in 1938 by Stefanowski and Petrow. Afterwards the two crews, Gromow, Jumaschew, Danilin and Baidukow, Belyakow, Spirin - Tschkalow had died in a crash in 1938 - prepared for the rigors of the flight by spending days in the pressure cabin. At the beginning of the Second World War, however, the program was discontinued.
The most obvious change to the two predecessors of the BOK-11 was an ATsch-40 diesel engine designed by A. D. Tscharomski, which was expected to increase the range, as well as a cabin with space for three crew members again. Two aircraft were converted in this form and tested in 1940, but the tests were discontinued for unknown reasons.
The BOK-15 with a further increased range did not get beyond the planning stage because the BOK was closed in 1941.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 3-4 |
| length | 13.92 m |
| span | 34.98 m |
| height | 5.50 m |
| Wing area | 87.90 m² |
| Wing extension | 13.75 |
| Undercarriage track width | 7.29 m |
| Preparation mass | 4200 kg |
| Payload | 7300 kg |
| Takeoff mass | 11,500 kg |
| Wing loading | 128.5 kg / m² |
| Power load | 13.4 kg / hp |
| Engine | a Mikulin M-34R |
| power | 550 kW (approx. 750 PS) |
| Top speed | 246 km / h |
| Cruising speed | 165 km / h |
| Service ceiling | 7000 m |
| Range | 13,000 km |
| Take-off run | 1590 m |
literature
- Rudolf Höfling: Tupolev . Airplanes since 1922. 1st edition. Motorbuch, Stuttgart 2012, ISBN 978-3-613-03459-4 , p. 42/43 .
- Wilfried Copenhagen , Jochen K. Beeck: The large aircraft type book. Commercial, transport, military, sport and touring aircraft and helicopters . Motorbuch, Stuttgart 2005, ISBN 978-3-613-02522-6 , p. 532 and 738/739 .
- Wilfried Bergholz: Russia's great aircraft manufacturer. Jakowlew, Mikojan / Gurewitsch, Suchoj. The complete type book . Aviatic, Oberhaching 2002, ISBN 3-925505-73-3 , p. 154 .
- Peter Alles-Fernandez (Ed.): Aircraft from A to Z. Volume 3: Koolhoven FK 56 – Zmaj . Bernard & Graefe, Koblenz 1989, ISBN 3-7637-5906-9 , pp. 372 .
- Heinz A. F. Schmidt: Soviet planes . Transpress, Berlin 1971, p. 147 .
Web links
Individual evidence
- ↑ Mikhail Maslow: Tupolev ANT-25. In: Aviation Classics 6/2011. Motor Presse Stuttgart, p. 33.
- ↑ Mikhail Maslow: Tupolev ANT-25. In: Aviation Classics 6/2011. Motor Presse Stuttgart, p. 30.
- ↑ Wilfried Bergholz In: Flieger Revue. 5/2000, section reader service, p. 64.
- ^ Ulrich Unger: 1937 - Moscow – North Pole. In: Flieger Revue. 3/1997, p. 51.
- ^ Karl-Heinz Eyermann , Wolfgang Sellenthin: The air parades of the USSR. Central Board of the Society for German-Soviet Friendship, 1967. p. 33.
- ↑ Valerij Tschkalow: Our transpolar flight (Moscow - North Pole - North America). SWA, Berlin 1946, p. 68
- ^ Ulrich Unger: 1937 - Moscow – North Pole. In: Flieger Revue. 3/1997, p. 52.
- ↑ Wilfried Copenhagen : Encyclopedia Soviet aviation. Elbe – Dnjepr, Klitzschen 2007, ISBN 978-3-933395-90-0 , pp. 34-35.