The task for fighter (DIP) with cannon armament and two crew members, which took place at TsAGI under the code ANT-29, appeared on July 26, 1931. The DIP was created according to the scheme of a two-engine low-wing aircraft with a smooth skin, retractable landing gear and closed cockpits.

The main work on the construction of the fighter unfolded in September 1934 and lasted five months. Senior engineer D. Romeiko-Gurko was the leader in this work.

The all-metal monoplane fighter with two M-100 engines entered factory tests on February 3, 1935. Test pilot N. Blagin, later known as the culprit of the Maxim Gorky plane crash, lifted the aircraft into the air (he performed a "loop" around the wing).

The main difference between the aircraft was the 102mm APK-8 cannon. The gun passed through the entire fuselage in its lower part, the reload tray protruded forward, and a diffuser came out of the tail unit. A crew of two actually sat astride this cannon. APK-8 ammunition consisted of 16 shells: 6 were in the tubular magazine and 10 - in the additional cartridge.

The machine-gun armament included three ShKAS: two - in the center section (without synchronization) and one - on the TUR-9 turret.

Powerplant. The DIP was supposed to be equipped with M-34 engines, however, during the construction, the Hispano-Suiza 12Ybrs of 760 hp each, assembled at the Rybinsk engine plant from French parts, was installed on the plane. Wooden propellers with a diameter of 3.4 m were already in the course of testing replaced with three-bladed metal propellers "Ratier" with a variable pitch on the ground.

Photo	Description
	Drawing ANT-29

A feature of the aircraft's design was the use of a completely smooth skin with blind riveting, as well as the presence of an APK-8 dynamo-reactive cannon Kurchevsky. The barrel of the cannon, which had no recoil, passed through the entire fuselage of the DIP aircraft - from the nose to the tail section, in which its nozzle was located. At the moment such a gun was fired, the action of the gases on the bottom of the projectile was balanced by the action of the reactive force developed by the nozzle.

Based on tests, it was concluded that it is necessary to increase the stabilizer, decrease the elevator, and also improve the efficiency of the rudder. To destroy the aircraft collapse to the right, it was required to install trim tabs on the ailerons. The water radiators of the power plant did not provide normal cooling of the engines and gave a leak after each landing. In addition, the aircraft was unstable at all possible operational alignments. Retracting of the chassis, testing of weapons and radio equipment was not carried out.

In conclusion of the Testing Act it was stated: "To consider it rational in the future to use the DIP aircraft for experimental and research work, having previously eliminated the shortcomings indicated in the report." After the termination of work on the APK-8 cannon the need for the plane disappeared, and it was removed from factory tests. The order to stop work on the RIP aircraft was received on March 28, 1936.

Bibliography

• Two-seat cannon fighter / Nikolay Gordyukov. /
• Aircraft for Kurchevsky's guns / Mikhail Maslov /
• Aircraft OKB A.N. Tupolev / Vladimir Rigmant /

October 27 2020.
May 15, 1935. In the crash of "Maxim Gorky" 11 crew members and 36 passengers from among TsAGI employees and their families were killed. The disaster occurred when Nikolai Blagin performed a third half roll around the ANT-20 wing. His I-5 crashed into the tandem propulsion system of the giant aircraft. Its destruction by fragments of the tail unit and the right wing of the ANT-20 led to the disaster. Nikolai Pavlovich Blagin was buried along with all those killed in the crash, his family members were paid a lump sum and a pension.
From a letter from the head of the NKVD G.G. Berries to Stalin on June 14, 1935: "... We have brought to criminal responsibility the workers of the cinema factory for military training films Ryazhsky V.G. and Pullin A.A., guilty of the fact that, without any permission, agreed with Blagin on the production of aerobatics for filming, which was the direct cause of the death of the plane "Maxim Gorky."

November 05 2020.
ANT-20 bis was actually built purely as a civilian aircraft. After Tupolev's arrest, the aircraft received the "neutral" designation PS-124 and was developed by I.F. Nezval.
Six M-34FRNV engines were installed on PS-124. According to the documents, their rated power was equal to 1050 hp. at a maximum of 1200 hp True, they write that the actual rated power did not exceed 1000 hp. The archaic wooden propellers "Maxima" were replaced by three-blade metal variable-pitch propellers VISH-4 with a diameter of 4.1 m, the bushings of which were covered with cocks.
The PS-124 passenger plane was designed to carry 60 passengers. The fuselage housed three saloons. The six-engine giant was transferred to the Moscow Directorate of the Civil Air Fleet. Since autumn 1939 PS-124 made regular flights on the line Moscow - Kharkov - Rostov-on-Don - Mineralnye Vody.

November 05 2020.
In November 1941 the Germans were already approaching Moscow. To fly a sluggish and clumsy giant in an area where Messerschmitts were snooping around with might and main seemed to be a clear suicide. And PS-124 was sent away from the front, to Central Asia. He became part of the Uzbek Directorate of the Civil Air Fleet and settled in Tashkent. The car was used on the lines Tashkent - Chardzhou - Urgench and Tashkent - Kuibyshev (Samara). They carried not so much people as various goods.
The plane flew by the Uzbek administration for a little over a year. It was exploited there more intensively than before. The average monthly flight time was almost twice that achieved in the Moscow administration. Many more passengers were taken on board than was provided for by the design. How they were placed is not very clear, whether they put additional chairs, or simply put them on the floor in the aisles and corridors.

December 12, 1942 PS-124 flew from Urgench to Chardzhou, delivering 85 passengers and 1925 kg of cargo. Two days later, the car continued on its way to Tashkent. Onboard there were 26 passengers and cargo. Not having reached 90 km to Tashkent, the giant suddenly began to descend. The decline was smooth at first, but the angle gradually increased. It ended with the PS-124 entering a dive and crashing into the ground. All passengers and ten crew members were killed.
Investigation revealed that pilot Govyaz was not in the cockpit at the time of the crash. In his seat sat the pilot Kozlov, not a member of the crew and flying as a passenger. Govyaz allowed him to "steer". Co-pilot Tropkov was supposed to look after him. The reason for the transition of the aircraft to a dive was that Kozlov intentionally or accidentally turned on the electric drive of the stabilizer for diving, the switch of which was on the armrest. The co-pilot either did not notice what Kozlov did, or did not have time to react.
This is how the ANT-20 understudy, the heir to Maxim Gorky, died, having finished the line of low-speed multi-engine corrugated giants in our country.