Kramer X-4 Air-To-Air Missile

red admiral

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16 September 2006
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One of the air to air missiles closest to use was the German X-4 wire guided missile. After reading of the British efforts in BSP4 I'm wondering how effective it would have been. Most of the British designs were rejected from lack of range but the X-4 is fairly similar. At the same time, the postwar beam riding missiles were a bit of a failure. How is a manually guided missile going to do? I have some concerns over the liquid fuel engine as well.

Any thoughts?

There were two pretty comprehensive articles in Flugzeug Classic last year. Apart from
the liquid fuel rocket engine, a solid fuel rocket was tested, too, although, IIRC, mainly due
to delays in the development of the chosen engine. The development of the X-4 was hampered,
too, by delays with the proximity fuse.
Against a bomber sized target, this missile probably could have been effective, if the attacker
wasn't shot down in time by escorting fighters ! A single seat fighter perhaps wasn't the best
choice, as the pilot couldn't maneuver freely, as long as he was guiding his missile.

P.S.: If you are interested in the mentioned article (in german !), just send a PM ...
From "Hitler´s guided weapons" by Dr. Alfred Price , "Aeroplane" January 2005


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The air-to-air rocket-propelled winged missile X-4 was designed by Max Kramer beginning in June, 1943. About 250 missiles were built and about 150 tested. The gross weight is 132 lb of which 44lb is war head. Propulsion is by means of a liquid fuel rocket weighing 31 lb (empty) and giving a thrust of 242 lb for 17 sec. About 19 lb of fuel were provided.

The missile is approximately 75 in. long, 8.7 in. in diameter, with wing span of 23 in. The speed is about 790 ftl sec, the horizontal range about 1.2 miles.

The missile has four sharply swept-back wings near the center of gravity and four tail fins. Aerodynamic control is by means of spoilers on the tail fins. Tabs on the wings cause the missile to spin. Two of the wings carry at the tips spools of fine wire 0.009 in. in diameter and long enough to permit a range of about three miles while maintaining direct-wire connection to the control aircraft. A gyrostabilized commutator in the missile and a suitable filter system permit direct electrical transmission of the control from the operator to the spoilers on the control surfaces of the missiles by means of the connecting. wires which can feed out at speeds of more than 650 ft/sec.

A document dated 11 January 1945 stated that 130 trials had been made. It was stated that the missile was in the early testing stage to prove its fundamental correctness of functioning. At one time the Air Ministry had a requirement for 5000 missiles by the middle of 1945 but this was later reduced. In February, 1945, SS leader Kammler ordered a lower priority and the closing out of the project at the end of the development period.

Kramer designed an acoustic proximity fuse for this missile known as "Kranich." About 30 were built and some preliminary fly-over and fly-by tests were made. The effective range was expected to be 45 ft. The tests which had been completed were promising. Work was also under way to develop an acoustic homing device with a hoped for range of from 1650 to 3300 ft.

Source: Guidance and Homing of Missiles and Pilotless Aircraft, May 1946


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Given how desperate they were for defensive weapons, and how much of an advance their guided weapons (including the surface-to-air ones) represented over AA artillery, cannons and unguided RP, it's surprising the Nazis never fired a few off in anger. What did they have to lose, after all?
pathology_doc said:
... What did they have to lose, after all?

After first tests (AFAIK still unguided) with single seat fighters (Fw 190), the X-4 was intended to be used from
multi seat/twin engined fighters only, because of problems with guiding the missile and flying the aircraft. Additionally
the guiding wires were endangered to be cut by the propeller in single engined fighters. The X-4 was limited to daylight
attacks, as the operator had to guide it visually. That would have meant daylight attacks by aircraft like the Me 110/410
or Ju 88 from distances of about 4000m, something that had already be proven to be more or less suicidal with the
appearance of escort fighter like the P-51 or P-47.

I am looking to get more info on the Rheinmetall-Borsig Feuerlilie F25. I am a rocket modeler from Germany. I built and flew successfully a 90% scale Kramer X4




Now I want to build a flying full scale Feuerlilie F25.

I am particularly looking for:

- accurate drawings (Post war from Allied Services?)

- pictures, especially from the F25 that is exposed in RAF Museum Cosford. The issue at the moment is to picture out the tailcone. Has anyone a detailled picture from the back/thrust plate of the F25? I cannot find anything. The tail cone looks really particular...

Thx for your help

I have a photo I took of the X-4 at Cosford a couple of years ago. It might be of some use to you.


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Thx, the X4 pics and text was only to inroduce myself to the forum. At the moment I look for plans, drawings or pics of any sort to start building a full scale Feuerlilie F25..

If someone has or can make a series of pictures of the F25 exposed in Cosford I would be really thanksfull, especially pictures from the aft of the bird.

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