Ruhrstal/Kramer X-1 (or Fritz-X, because it's easier to say)

The agreed surrender of the Italian fleet to the Allies in September 9, 1943 saw the battleships Italia (damaged) and the Roma (sunk) as targets of a new type of air-launched weapon, the Ruhstahl/Kramer X-1 (or Fritz-X) guided bomb.

This was a free-fall bomb that could be guided towards its target after release from an altitude of about 19,685 ft (6000 m); by the time it had reached its target, perhaps a mile and a half away, the weapon would be traveling about the speed of sound.

Control was by means of electromagnetically operated spoilers being operated by radio control from the parent aircraft, frequently a Dornier Do 217. After releasing the weapon, the parent aircraft throttled back and was taken to a higher altitude so that it was directly over the target at the moment of impact, the bomb-pilot having kept track of the weapon with the assistance of a standard Lofte 7 bombsight. Wire-link control using transmission lines was abandoned as an economy measure.

Tests were begun in Germany during 1942, later the tests were moved to Italy. Here pneumatic power was experimentally substituted for electro-magnetic actuation of the spoilers, but variations in temperature created problems so the idea was dropped.

The Allied assault on Italy meant that the Fritz-X was pressed into increased use: the cruiser USS Savannah was successfully attacked as were some naval transports. In the confusion created as a result of the night attack two British cruisers collided. Seven days later the battleship HMS Warspite was hit by three armor-piercing Fritz-X bombs. She was so damaged that she had to be towed to Malta for repair.

About 66 of the bombs were produced each month, far short of the target figure. About half of those produced were used for tests conducted during 1943 and 1944.

The real downfall of the Fritz-X was not due to productions problems, but rather the high loss rate of launch aircraft. Since the plane had to linger at low speed over the target, they became vulnerable to fire and made inviting targets for ship gunners.


  • Type: free-fall guided bomb
  • Powerplant: none
  • Performance: maximum speed: 643 mph
  • Weight: round- 3,461 lb
    explosive- 705.5 lb
  • Dimensions: span- 4 ft 5.2 in
    length- 10 ft 8.4 in
    fuselage diameter- 1 ft 10.1 in
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