The DFS 346 was developed in Germany in the closing stages of the Second World War as a jet glider and reconnaissance aircraft. It was developed by Felix Kracht in tandem with a similar project as part of Nazi Germany’s research into jet and rocket technology. Unusually for Nazi military projects though, the DFS 346’s full construction and testing began in the immediate aftermath of the war.
The Soviets gathered much of Kracht’s research and sought to exploit the idea to their advantage. Tests yielded interesting results in terms of aerodynamics, but the project was stopped after several accidents.
The DFS 346 was the brainchild of designer and aerospace engineer Felix Kracht. At the time, Kracht was working for the Deutsche Forschungsanstalt für Segelflug (German Institute for Sailplane Flight, DFS) which focused on developing glider technology. In the run-up to the war it had been tasked by the Nazi government to build leisure and military sailplanes to help train members of the Hitler Youth and the Luftwaffe.
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Kracht had established himself as a skilled engineer and pilot and made headlines after crossing above the Alps in 1937 using one of his own glider designs.
During the war, the Nazi regime began to explore rocket and jet engine technology for potential cruise missiles, bombers or interception aircraft. A small but significant degree of research was also devoted to building rocket-powered high-altitude reconnaissance aircraft.
In 1944, Kracht began work on the DFS 228, an experimental glider aircraft. He had conceived most of the drawing work before the war broke out but was given financial backing by the German Ministry of Aviation in 1940 to complete the project.
Kracht conceived this first design as a fixed-wing glider with fixed skid landing gear and a pressurized cabin to allow for comfortable high-altitude flight. Most importantly, the glider would also have the capability of carrying a rocket power for powered flight.
Test flights with the rocket were due to have taken place in early 1945. Shifting priorities led to the project stalling as the German high command was preoccupied with Allied advances into occupied Europe and then Germany itself.
However, Kracht had also worked on a design in tandem with his DFS 228 creation and applied lessons he had learned from developing it.
The result was the DFS 346.
Unlike his other glider concept, Kracht developed the 346 with backwards swept wings and a streamlined fuselage to ensure a high speed. Kracht hoped his new design would be capable of breaking the sound barrier. The glider would also feature an all-metal skin and airframe.
To compensate for the increased g-forces faced by the pilot, the cockpit was designed for the pilot to be in the prone position: lying on their front to fly the aircraft rather than in a traditional seated position.
The DFS 346 was also designed with an escape capsule should it be struck by enemy fire.
Power would be provided by two Walter HWK 109-509 rocket units which could propel the glider to a top speed of Mach 2 and an average cruising ceiling of around 100,000 feet. The idea was that one rocket unit would propel the DFS 346 to its top speed and altitude before the second unit would activate, providing bursts of power to keep the glider airborne and at a speed where it could outrun Allied fighters.
For launching, Kracht envisaged that the DFS 346 would be carried into the air by a mother aircraft, which would have likely been a Dornier Do 217 bomber. The bomber would get within range of the launch spot before the pilot would release the glider.
The glider’s rocket would power the aircraft to perform a reconnaissance run over Britain before gliding home to a Luftwaffe base in Germany or occupied France.
A working prototype was to be built by German aircraft manufacturer Siebel. A wind tunnel model was made and tested by Siebel. The initial results were deemed satisfactory and construction on a working prototype began. However, the new glider project met the same initial fate as its DFS 228 cousin by being shelved shortly before the end of the war.
Although the end of the war could have killed the project altogether, the DFS 346 fell into interesting circumstances that led to its revival.
The Siebel facilities with the 346 models were captured by the advancing Soviet Red Army in 1945 and the project was deemed something of strategic interest by the Soviet authorities.
Although the Soviets had found a common cause in defeating the Nazi regime with the British and Americans, growing ideological tensions between the two powers marked the beginning of the Cold War.
The Soviets attempted a similar strategy to the American government by clandestinely transporting or forcibly recruiting former Nazi scientists and engineers along with their research into Russia in an attempt to exploit their knowledge and gain a technological advantage.
In October 1946, the Soviet Design Bureau 2 (OKB-2) packed up all of the equipment and unfinished parts of the glider and ordered the resumption of the prototype under the direction of engineers Hans Rössing and Alexandr Bereznyak.
The Soviets renamed the prototype the Samolyot 346 and resumed wind tunnel tests in the late 1940s. The Soviet tests yielded signs of potential flaws in the design. For example, it was found that the aerodynamics of the glider would result in an uncoverable stall if the pilot increased the angle of attack during takeoff or climb out. It was also believed the glider would not be capable of reaching Mach 1 despite its premise of being an incredibly fast aircraft.
Nonetheless, the Soviet regime ordered that production and research into the DFS 346 continue. It was worked on under a team of German scientists and aero engineers who were transported by the Soviets to Russia.
The engineers placed wing fences on the design to mitigate the risk of a stall and tested the escape capsule by fitting it to a B-25 bomber. The tests indicated the capsule design worked as intended and was kept.
In 1947, the working DFS 346 prototype was taken for its maiden flight. It was not fitted with a rocket motor and the first flight would be without power, but it had incorporated design improvements from its wind tunnel trials.
The test pilot for the run was Wolfgang Zeise, a German national who had worked as a chief test pilot for Siebel. The glider was carried into the air on a Tu-4, which was a Soviet carbon-copy of the American B-29.
In his feedback, Zeise found that the glider had no issues in flight and that its performance was good although some minor improvements could be made to increase its abilities. Spurred on by Zeise’s reports, the Soviets ordered three more prototype units to be built.
Based on the recommendations that Zeise provided after his first flight, the DFS 346 was developed into an updated model and sent for a second engineless test flight on the 10th of September 1948. Unfortunately, the second flight produced a number of issues, some of which were found to be potentially fatal.
Zeise found the updated glider difficult to control in the air. While attempting to land, the glider flew too fast and initially contacted the ground at around 195 miles per hour.
The glider bounced about 12 feet in the air and kept flying for almost half a mile down the runway before crashing into the ground for a second time causing the ski landing gear to collapse. The crash also showed weaknesses in the safety harness which broke on impact and resulted in Zeise being thrown about the cockpit before being knocked unconscious.
Fortunately for Zeise, he was not seriously injured in the crash. The 346 was repaired and handed to another test pilot, a Russian national known as P. Kazmin who conducted a number of test flights from 1950 to 1951 at a Soviet Air Force base near Lukhovitsy. Some of these test runs also resulted in belly landings and minor accidents before Zeise returned as a chief test pilot in May 1951.
The Soviet authorities demanded a powered test to see if the rocket unit was capable of producing the power that Kracht had intended for it. Kracht was again put at the controls and a powered flight using the rocket motor was scheduled for the 13th of August 1951.
The first part of the powered flight went without incident. The glider was towed above Lukovici in Yugoslavia and was released successfully. Zeise fired up the rocket unit and powered the glider to a speed of 560 miles per hour. The rocket worked as planned, with it using bursts to fire up and power down while maintaining the glider’s momentum and speed.
However, midway into the flight, Zeise radioed to say the controls had stopped responding and the aircraft was rapidly losing altitude. He was able to get out using the escape capsule and parachuted back to earth. The DFS 346 then plummeted into the ground and exploded on impact.
With the loss of the working prototype, the Soviet government decided to abandon the project and no further updates were made to the design.
Despite its mixed results in test runs, the DFS 346 did show promise. Unlike other former Nazi jet or rocket projects which remained consigned to an unfinished prototype stage, the DFS 346 did see extended research life under the Soviet government.
Although Kracht played no formal role in the glider’s continued development after it was taken by the Soviets, Kracht himself remained active as an aerospace designer and worked in France after the war before returning to Germany to take up a position with Airbus. He passed away in 2002.
- Crew: One pilot
- Length: 44 ft 1 in (13.45 m)
- Height: 11 ft 7 in (3.54 m)
- Empty weight: 4,806 lb (2,100 kg)
- Loaded weight: 11,506 lb (5,230 kg)
- Powerplant: 1× Walter HWK 109-509 rocket, 33.4 kN (7,500 lbf) 33.4 kN