Hitler’s Last Ditch SS Interceptor; The Junkers Klf 255

April 1, 2023

The final days of the Third Reich saw some truly remarkable aircraft fly in a desperate attempt to stem the inevitable defeat. But perhaps few offered as much potential as the Junkers Klf 255.

This aircraft roots were based in its inventor, Helmut von Klagenfurt, witnessing the destruction of German aircraft by Allied fighters as they were trying to take off on several occasions throughout the latter half of 1944. Klagenfurt was a researcher at the Institute of Aerodynamic Research at the University of Göttingen and an expert in aerodynamics, apparently working on several Luftwaffe types throughout the war as part of various programs.

Seeing the effectiveness of Allied airpower in preventing German fighters getting airborne convinced Klagenfurt that a radical solution had to be found. In short, he recognised that using a conventional airfield was now far too dangerous.

Klagenfurt envisaged using a rocket launched interceptor that would use a rail-mounted trolley as a launch platform. The aircraft would be stored in an underground bunker or cave, where it could be fueled and armed, and then take the pilot on board. To launch, the aircraft would fire its rocket motors and accelerate out of its protected hanger along a length of rail track, with Klagenfurt calculating that 500 metres (1,640 feet) of track being sufficient. This would be far more discreet and easier to repair than a conventional runway.

The rail launch would enable the rocket interceptor to get airborne in a matter of seconds, at which point the trolley could be winched back into the tunnel for taking on another interceptor. All of this would minimise the amount of time the interceptor was exposed to attack and mean the “airbase”, if that’s the right term, was immune from being destroyed. It was also thought that the process could be very rapid, with a single track having the potential, with the right handling apparatus, of conducting three launches in a minute.

By late October Klagenfurt had an initial conception design drawn up and reached out to his contacts at the Reich Air Ministry (RLM). They were not receptive.

The RLM had been directed by Albert Speer to maximise production of existing types or specifically directed projects, like the He 162 “People’s Fighter”, and so they were not in a position to authorise a completely new concept, let alone aircraft.

But Klagenfurt was given contact details for the one place were such a scheme as his could be authorised, a Colonel in the SS who was a close friend of Heinrich Himmler. This seems to have worked and he was ordered to report to Berlin in early November to present on his proposal. This evidently created a favourable impression, and Klagenfurt reportedly ended up giving a further briefing on his idea not just to Himmler, but to Hitler himself.

Always a sucker for a grand idea, and not an adherent to Speer’s practicality on Germany’s war production, Hitler authorised the idea on the spot and wanted a prototype for testing built as soon as possible. And because the Luftwaffe had singularly failed to stop the Allied air forces, the intent was for the pilots to be drawn from the ranks of the SS, further cementing that organizations role, and the ambitious Himmler’s, in subverting the capabilities of the German military.

With Hitler’s interest, Himmler’s keen support and Klagenfurt’s extensive drawing and calculations, things proceeded extremely quickly. Junkers were assigned the job of overseeing the construction of the new aircraft, now designated as the Klf 255, and they built the light alloy glazed fuselage while the wings and control surfaces were built out of wood and outsourced to carpentry manufacturers. By using this mixed construction technique it was hoped, if testing was successful, that the Klf 255 would be both cheap and fast to mass produce. This proved to be the case, with the prototype largely ready by the beginning of March.

It was a truly unbelievable design.

A canard design, the pilot lay prone in the pressurized nose capsule so as to help compensate for G-forces he would experience in the rapid climb to intercept. Armament was two of the formidable MK 108 30mm cannon, though its possible the aircraft might have taken 50mm MK 112 or 55mm MK 115’s instead, though no armament was fitted in the prototype, the Klf 255 V1.

Propulsion was supplied by a Walther HWK 109-509 A-2 rocket engine that produced a maximum thrust of 3,800lbf. This engine was able to be switched to a lower cruise setting once take off and zoom to altitude was achieved, and the engine had an estimated seven minutes of burn time in combat conditions. The internal motor was supplemented by four solid-fuel rockets that produced almost 4,000lbf each and burnt for four seconds before jettisoning off the airframe.


These would be activated when the aircraft separated from the trolley and the pilot began his climb to altitude.

Though the vast majority of the aircraft was completed by the beginning of March there was a brief delay as cockpit instrumentation was in critically short supply for the Germans at this stage of the war and they reportedly had to use parts salvaged from crashed aircraft to complete the Klf 255 V1. But by the 1st of April, 1945 – seventy-eight years ago today – the aircraft was ready for its first test flight.

In front of dignitaries, technicians and scientists involved in the program, the test pilot, Major Spaßen, was sealed inside and, with everyone taking the precaution of staying in a concrete bunker, activated the aircrafts rocket motor.


The aircraft acted as hoped, swiftly accelerating along its rails and then achieved separation, lifting free into the sky. At this point Spaßen fired his rocket boosters…and things went wrong.


The Klf 255 suddenly veered off course and, performing a parabolic curve, smashed into the nearby forest that surrounded and obscured the test facility. The Major was killed and the tragedy marked the end of the program, hardly surprising as Germany was just over a month from capitulation.

The Klf 255 in fact passed into myth, only being revived when a French magazine unearthed details on the program and published them in 1973. And that is the story of Junkers Klf 255; the last-ditch SS Rocket interceptor.



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