Editing DFS 346 (section)

==Development==

===Concept===
[[File:Dfs346 box.JPG|thumb|250px|right|Concept art]]
[[File:DFS 228 cockpit test.jpg|thumb|250px|right|Test pilot Rolf Mödel tries out the prone position.]]
The DFS 346 was a parallel project to the [[DFS 228]] high-altitude [[reconnaissance]] aircraft, designed under the direction of Felix Kracht and his team at [[Deutsche Forschungsanstalt für Segelflug|DFS]]. While the DFS 228 was essentially of conventional [[sailplane]] design, the DFS 346 had highly-swept wings and a highly streamlined fuselage that its designers hoped would enable it to break the [[sound barrier]].

Like its stablemate, it also featured a self-contained escape module for the pilot, a feature originally designed for the [[DFS 54]] prior to the war. The pilot was to fly the machine from a prone position, a feature decided from experience with the first [[DFS 228]] prototype. This was mainly because of the smaller cross-sectional area and easier sealing of the pressurized cabin, but it was also known to help with [[g-force]] handling.

The 346 design was intended to be air-launched from the back of a large [[mother ship]] aircraft for [[air launch]], the carrier aircraft being the [[Dornier Do 217]]. After launch, the pilot would fire the 346's [[Walter HWK 109-509|Walter 509B/C]] twin-chamber "cruiser" engine to accelerate to a proposed speed of [[Mach number|Mach]]{{nbsp}}2.6 and altitude of 30,500 meters (100,000&nbsp;ft). This engine had two chambers — the main, upper ''Hauptofen'' combustion chamber as used on the earlier HWK 509A motor; but capable of just over two short tons (4,410&nbsp;lbf) of thrust at full power (more at altitude), and the lower-thrust ''Marschofen'' throttleable chamber below the main unit of either 300&nbsp;kg (B-version) or 400&nbsp;kg (C-version) top thrust levels mounted beneath the main chamber.  After reaching altitude, the speed could be maintained by short bursts of the lower ''Marschofen'' cruise chamber.  The question of what rocket-motor subtype was to be used (the 509B or -C) is not adequately addressed here.

In an operational use the plane would then glide over [[England]] for a [[reconnaissance|photo-reconnaissance]] run, descending as it flew but still at a high speed. After the run was complete the engine would be briefly turned on again, to raise the altitude for a long low-speed glide back to a base in [[Nazi Germany|Germany]] or northern [[France]].

===Prototype construction===
Since the aircraft was to be of all-metal construction, the DFS lacked the facilities to build it and construction of the prototype was assigned to [[Siebel|Siebel Werke]] located in [[Halle, Saxony-Anhalt|Halle]], where the first [[windtunnel]] models and partially built prototype were captured by the advancing [[Red Army]].

===Post-War===
On 22 October 1946, the Soviet [[OKB-2]] (Design Bureau 2), under the direction of Hans Rössing and Alexandr Bereznyak, was tasked with continuing its development.
The captured DFS 346, now simply called '''"Samolyot 346"''' (''samolyot'' means "airplane") to distance it from its German origins, was completed and tested in TsAGI [[wind tunnel]] T-101. Tests revealed some aerodynamic deficiencies which would result in unrecoverable [[Stall (flight)|stall]]s at certain [[Angle of attack|angles of attack]]. This phenomenon involved a loss of longitudinal stability of the airframe. After the wind tunnel tests, two [[wing fence]]s were installed on a more advanced, longer version of the DFS-346, the purpose of fences was to interrupt the spanwise movement of airflow that would otherwise bring the boundary-layer breakdown and transition from attached to stalled airflow with loss of lift and increase of drag.

This solution was used on the majority of Soviet planes with swept wings of the 1950s and 1960s. In the meantime, the escape capsule system was tested from a [[B-25 Mitchell|B-25J]] and proved promising. Despite results from studies showing that the plane would not have been able to pass even Mach 1, orders were given to proceed with construction and further testing.