DFS 346 – German designed, Soviet trialed rocket plane

DFS 346 rocket-powered aircraft

The DFS 346 was a rocket-powered reconnaissance aircraft prototype developed by the Germans in the later stages of the Second World War. It was designed by Felix Kracht who at the time was working for DFS (Deutsche Forschungsanstalt für Segelflug) – or in English, the German Research Institute for Sailplane Flight. The DFS 346 was developed alongside the DFS 228 project which was a high-altitude low-speed reconnaissance sailplane. In sharp contrast however, the DFS 346 was envisaged as a super high-speed rocket powered aircraft with swept wings and a streamlined fuselage. Interestingly the aircraft also featured an unusual prone-pilot cockpit, not dissimilar to the one used in the later Gloster Meteor “Prone Pilot” experimental aircraft.

The idea behind the DFS 346 project was to create an aircraft which could take reconnaissance photos of England before returning to base in either northern France or Germany. The mission would involve the aircraft being transported close to its intended surveillance target by a carrier aircraft – in this case the Dornier Do 217. After release, the pilot would fire up the rocket motor and accelerate to an estimated top speed of Mach 2.6 while climbing to an altitude of 100,000 ft (30,500 metres). The pilot would then glide over his target while descending, using the rocket motor in bursts to maintain speed. After taking photos the pilot would then head for home, gliding his aircraft back to base. Well that was the idea anyway. The war ended before the aircraft was finished.

But like so many futuristic German aircraft, after the war ended, the plans ended up in the hands of the allies. In this case the Soviets. In October 1946 the Soviet design bureau OKB-2 was tasked with carrying on where DFS had left off, finalizing the design and constructing a series of prototypes. Early wind tunnel tests showed the original design was susceptible to unrecoverable stalls in certain scenarios. Engineers managed to rectify this by adding two small vertical stabilizers – called wind fences – to each wing, and also lengthening the fuselage. At the same time the unusual escape capsule system was also tested and it proved to be effective.

DFS 346 rocket-powered aircraft

In 1947 the first full size prototype was built. It was a glider, no engines were fitted, although ballast was added to compensate. It was carried to altitude by a captured B-29 (the Soviets, to the great annoyance of the US, interned 3 aircraft and their crews during the war). The DFS 346 test pilot was Wolfgang Zeise, and the first flights were successful, leading to a further three prototypes being constructed.

In 1948 the first of the three new prototypes flew. It featured a few minor aerodynamic alterations and in place of the ballast it had a dummy engine fitted. Zeise was again the pilot. After release at 9,700 metres (31,800 ft), Zeise realised he had very little control of the aircraft. He brought it in for landing at too fast a speed and descended to rapidly. The aircraft bounced several metres into the air and continued to glide for several hundred metres. The second time it touched down the landing ski collapsed and the fuselage slammed into the ground. Zeise was knocked unconscious in the accident after hitting his head on the canopy. Analysis of the incident placed the blame on Zeise for not fully deploying the landing ski. Although it was also acknowledged that it was a very difficult aircraft to fly. Any thought of rocket-powered flight was put on the back burner, so to speak, until control of the glider version was more predictable.

DFS 346 rocket-powered aircraft

Late in 1950 and in early 1951 a number of test flights of the DFS 346 was undertaken by another pilot, P. Kamsin. Most of these were successful, but again the landing skid proved to be unsatisfactory, and the second prototype aircraft ended up on its belly. Later in 1951 Zeise returned to the program, and flew the now repaired second prototype and also the third prototype several times without accidents. In the summer of 1951 the first powered flight of the DFS 346 took place with Zeise at the controls. He flew it again under power on September 2nd without incident. On both these flights the aircraft broke the sound barrier. Then in on September 14th he took the DFS 346 for what was to be its final flight.

After being dropped from the carrier aircraft at 30,500 ft (9,300 m), Zeise fired up the rocket and accelerated to 560 mph. He began to climb, and soon passed the B-29 from which he had been released. Shortly after however, Zeise radioed that the aircraft was not responding to the controls, and furthermore he was losing altitude. At this point mission controllers told him to bail out of the unresponsive aircraft. Fortunately the escape capsule system worked perfectly, and after exiting the doomed DFS 346 at 21,000 ft (6,500 metres) Zeise safely floated down to earth by parachute.

After the complete destruction of the third and final prototype, the project was abandoned. It had never lived up to its promise of Mach 2.6, in fact it had only twice broken the sound barrier, just. Furthermore its unpredictable handling meant it was clearly only a matter of time before someone got killed.

I imagine Wolfgang Zeise was a very happy man the day the DFS 346 got canned.

Leave a Reply