As the carrier of this miracle weapon, the Dornier Do 217 bomber was supposed, at that time in the earlier versions it was still diving. A huge 12-meter rifled gun barrel was located on the external suspension under the fuselage of the aircraft. 700 kg of projectile was loaded into the barrel, the length of which was 1.2 meters, containing 35 kg of explosive, then 70 kg of accelerating charge of smoke powder and the whole system was closed by 700 kg of a counterweight located on the breech. According to the developers's idea, during the shot, the charge accelerated the projectile to an initial speed of 280 m / s, and the counterbalance flying out of the breech in the opposite direction compensated for the return. The mass of the loaded gun was 4237 kg. The estimated speed of the projectile in flight was about 125 m / s, which was clearly not enough for lay shooting at a long distance, so the developers formulated a certain tactic for using this weapon. The booster plane SG 104 was supposed to launch an attack at high altitude, after which it would enter a steep peak at an angle of 50 to 80 ╟ and fire a shot from a height between 6,000 and 2,000 meters. The estimated flight time of a projectile during a shot at a 50-degree peak from 6 thousand meters was 16 seconds, if you dive at an angle of 80 degrees when shooting from a height of 2 thousand meters, the time was reduced to 4.4 seconds. At the same time, the projectile, receiving additional acceleration under the influence of gravity, at the moment of meeting with a potential target would have a quite acceptable speed, respectively 449 and 468 m / s.
But, as usual, "it was smooth on paper ..."
Tests of the experimental installation were carried out on October 19, 1940, for which the trunk of the experimental installation was placed on a wheeled trolley mounted on rails, and the nose and tail of the Dornier Do 217E-1 bomber were mounted on top of it, which was important for assessing the potential impact of muzzle gases on an airplane glider . In this case, the charge mass was reduced. However, when fired, the tail of the aircraft was seriously damaged. In addition to the direct effect of the gas jet, an additional wave was reflected on it, reflected from the ground.
Ground tests continued until mid-1941, during which 14 shots were fired from three manufactured SG 104 guns.
We experimented with the mass of the charge, the angles of installation of the barrel, but did not achieve satisfactory results. By this time, there were problems with the media. The Do 217 bomber, originally developed as a dive, did not take place in this capacity, turning over time into a regular horizontal one. And the load of more than 4 tons was close to the limit for him. In this regard, the Junkers Ju 288 promising bomber began to be considered as a carrier in the later stages of the project. The Junkers version with a gun inside the company bore the unofficial designation Ju 288G √ from "G" - "gerät", although it was never built "in iron". In all likelihood, the projects of the Ju 288G carrier and the Sondergerät SG 104 Münchhausen developments moved in parallel courses, since when the SG 104 project was finally buried in mid-1941, the development of the Ju 288G carrier continued for some time. And at a later stage, as an armament, it was considered another, more modest in size, sample of the work of the Rheinmetall company - a 280-mm recoilless gun Düsenkanone 280 or otherwise Düka 280.
This tool was developed by Rheinmetall Borzig engineer Kleinschmidt, the author of all projects recoilless guns born in the company. Unlike the Sondergerät SG 104's 355.6-mm non-recoil recoil, the Düka 280 was even larger in size - 14.7 meters, but fired with lighter shells weighing "only" 400 kg. No counterweight was provided; the gun was designed according to the classical scheme, with the removal of "unnecessary" gases through the gas outlet channel back. The estimated initial velocity of the projectile was about 560 m / s, which made it possible to do without steep diving when firing to achieve acceptable characteristics. The estimated armor penetration of the projectile from a distance of 2 thousand meters was 200 mm. In the Ju 288G project, the Düka 280 gun was supposed to be placed already inside the aircraft, organically fitting into the fuselage. A gas outlet can be discharged by analogy with the Düka 8.8 project up and down from the axis of the barrel.
The Düka 280 gun was tested in late 1941 - early 1942, however, even such a reduced caliber was excessive for installation on an airplane. By the end of 1942, the theme of the "air battleship" was finally buried, and prototypes of recoilless guns Düka 280 and SG 104 were sent to the scrap. Missile weapons, actively developed in Germany, promised significantly greater prospects for development.
A little later, closer to the end of the war, the theme of recoilless guns for mounting on an airplane received a new breath in terms of the appearance of special devices Sondergerät 113 "Förstersonde", Sondergerät 116 and Sondergerät 118 "Zellendusche", Sondergerät 500 "Jägerfaust", which are much more modest in size and power designed to combat both armored vehicles on the battlefield, and with enemy bombers. But these devices are somewhat beyond the scope of the story and deserve a separate description.
Modification
SG 104 Münchhausen
Düka 280
Caliber mm
Rate of fire, rds / min
Muzzle velocity, m / s
Gun mass, kg
Gun length, mm
Projectile weight, kg
355.6
single charge
280
4237
11.25
700
280
single charge
560
14.7
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