Question: The ANT-8 was an experimental flying boat designed by a pioneering aircraft designer of what nationality?

full_context: Document 1: Tupolev ANT-37: The Tupolev ANT-37 (or DB-2) was a Soviet twin-engined long-range bomber designed and built by the Tupolev design bureau, the design team operating under the guidance of Pavel Sukhoi. The aircraft did not enter production, but three examples of the type were used for research and record breaking flights.
Document 2: Antonov An-225 Mriya: The Antonov An-225 "Mriya" (Ukrainian: Антонов Ан-225 "Мрія" (dream or inspiration) , NATO reporting name: "Cossack") is a strategic airlift cargo aircraft that was designed by the Antonov Design Bureau in the Ukrainian SSR within the Soviet Union during the 1980s. It is powered by six turbofan engines and is the longest and heaviest aircraft ever built, with a maximum takeoff weight of 640 t . It also has the largest wingspan of any aircraft in operational service. The single example built has the Ukrainian civil registration UR-82060. A second airframe with a slightly different configuration was partially built. Its construction was halted in 1994 because of lack of funding and interest, but revived briefly in 2009, bringing it to 60%-70% completion. On 30 August 2016, Antonov agreed to complete the second airframe for Aerospace Industry Corporation of China (not to be confused with the Aviation Industry Corporation of China) as a prelude to AICC commencing series production.
Document 3: Chyetverikov ARK-3: The Chyetverikov ARK-3 ("ARKtichyeskii" - arctic) was an Arctic multi-role flying boat designed and built in the USSR from 1933 featuring a conventional flying boat hull, with high cantilever wings equipped with floats at mid-span. The two engines were mounted in tractor-pusher fashion on a pylon above the fuselage.
Document 4: Andrei Tupolev: Andrei Nikolayevich Tupolev (Russian: Андрей Николаевич Туполев ; November 10, 1888 – December 23, 1972) was a pioneering Soviet aircraft designer.
Document 5: Mikhail Gurevich (aircraft designer): Mikhail Iosifovich Gurevich (Russian: Михаи́л Ио́сифович Гуре́вич ) (12 January 1893 [O.S. 31 December 1892] – November 12, 1976) was a Soviet Jewish aircraft designer, a partner (with Artem Mikoyan) who co-founded the famous MiG military aviation bureau. MiG is an abbreviation of their surnames. The bureau now simply known as Mikoyan, is famous for its fighter aircraft, rapid interceptors and multi-role combat aircraft which were staples of the Soviet Air Forces throughout the Cold War. The main focus in designing the aircraft were on high speed, fast ascent, and high flight altitude. The bureau designed 170 projects of which 94 were made in series. In total 45000 aircraft of "MiG" brand have been manufactured domestically, of which 11000 aircraft were exported. Over 14000 "MiG" fighters have been produced under licence abroad. The last plane which Gurevich personally worked on before his retirement was the Mig-25.
Document 6: Boeing XF8B: The Boeing XF8B (Model 400) was a single-engine aircraft developed by Boeing during World War II to provide the United States Navy a long-range shipboard fighter aircraft. The XF8B was intended for operation against the Japanese home islands from aircraft carriers outside the range of Japanese land-based aircraft. Designed for various roles including interceptor, long-range escort fighter, dive-bomber, and torpedo bomber, the final design embodied a number of innovative features in order to accomplish the various roles. Despite its formidable capabilities, the XF8B-1 was fated never to enter series production.
Document 7: Sukhoi: Nine years prior to the creation of the bureau, Pavel Sukhoi, a Soviet Russian aerospace engineer, took over team no. 4 of the CAHI's AGOS aviation, flying boat aviation and aircraft prototype engineering facility, in October 1930. Under Sukhoi's leadership, the team of the future design bureau started to take shape. The team, under the Tupolev OKB, produced experimental fighters such as the I-3, I-14, and the DIP, a record-breaking RD aircraft, the Tupolev ANT-25, flew by famous Soviet aviators, Valery Chkalov and Mikhail Gromov, and the long-range bombers such as the Tupolev TB-1 and the Tupolev TB-3.
Document 8: Semyon Lavochkin: Semyon Alekseyevich Lavochkin (Russian: Семён Алексе́евич Ла́вочкин ; September 11, 1900 - June 9, 1960), a Soviet aerospace engineer, Soviet aircraft designer who founded the Lavochkin aircraft design bureau. Many of his fighter designs were produced in large numbers for Soviet forces during World War II.
Document 9: Tupolev: Tupolev (Russian: Ту́полев , ] ) is a Russian aerospace and defence company, headquartered in Basmanny District, Central Administrative Okrug, Moscow. Known officially as Joint Stock Company Tupolev, it is the successor of the Tupolev OKB or Tupolev Design Bureau (OKB-156, design office prefix Tu) headed by the Soviet aerospace engineer A.N. Tupolev. The company celebrated its 90th anniversary on October 22, 2012. The Russian government merged Tupolev with Mikoyan, Ilyushin, Irkut, Sukhoi, and Yakovlev as a new company named the United Aircraft Corporation.
Document 10: Tupolev ANT-8: The ANT-8 was an experimental flying boat designed by Tupolev. It was designated the "MDR-2" (MDR meaning "Morskoi Dalnii Razvedchik", or Naval Long-Range Reconnaissance) by the military.
Document 11: Artem Mikoyan: Artem (Artyom) Ivanovich Mikoyan (Russian: Артём Ива́нович Микоя́н ; Armenian: Արտյոմ (Անուշավան) Հովհաննեսի Միկոյան "Artyom (Anushavan) Hovhannesi Mikoyan" ; 5 August [O.S. 23 July] 1905 – 9 December 1970) was a Soviet Armenian aircraft designer. In partnership with Mikhail Gurevich he designed many of the famous MiG military aircraft.
Document 12: Boris Lisunov: Boris Pavlovich Lisunov (Russian: Борис Павлович Лисунов , 19 August 1898 – 3 November 1946) was a Soviet aerospace engineer.
Document 13: Pavel Sukhoi: Pavel Osipovich Sukhoi (Russian: Па́вел О́сипович Сухо́й ; Belarusian: Па́вел Во́сіпавіч Сухі́ ) (22 July 1895 – 15 September 1975) was a Soviet aerospace engineer. He designed the Sukhoi military aircraft until the 1970s, and founded the Sukhoi Design Bureau.
Document 14: Tupolev TB-3: The Tupolev TB-3 (Russian: Тяжёлый Бомбардировщик , Tyazholy Bombardirovschik, Heavy Bomber, civilian designation ANT-6) was a heavy bomber aircraft which was deployed by the Soviet Air Force in the 1930s and during World War II. It was the world's first cantilever wing four-engine heavy bomber. Despite obsolescence and being officially withdrawn from service in 1939, the TB-3 performed bomber and transport duties throughout much of World War II. The TB-3 also saw combat as a Zveno project fighter mothership and as a light tank transport.
Document 15: Alexei Tupolev: Alexei Andreyevich Tupolev (Russian: Алексе́й Андре́евич Ту́полев ; May 20, 1925 – May 12, 2001) was a Soviet aircraft designer who led the development of the first supersonic passenger jet, the Tupolev Tu-144. He also helped design the Buran space shuttle and the long-range heavy bomber Tu-2000, both of which were suspended for lack of funding.
ground_truth: Soviet