The Great Panjandrum, two 3-meter-wide (10 ft) rocket-powered wheels attached to a drum filled with explosives, was as peculiar and powerful in practice as it sounds. The Panjandrum was supposed to accelerate across a beach to the speed of a car and blow a massive hole in the German defenses that British troops and tanks could roll through.
Unsurprisingly, the rocket-powered speeding explosive was unpredictable in practice. The Panjandrum was critically unstable and could never be relied upon to go entirely in the direction in which it was pointed.
The designers tried adding a third wheel and steel cables for steering, but nothing really helped. On top of that, when the Panjandrum reached its top speed of 97 kilometers per hour (60 mph), the rockets had a habit of detaching.
Despite this, the Panjandrum was tested in front of top members of the militaryin January 1944. The test began well. The Panjandrum rolled through the surf in a straight line and began to accelerate. As it started to reach higher speeds, though, the rockets began to detach and fire off in all directions.
The Panjandrum became a spinning wheel of flames that nearly ran down the official cameraman. As the Great Panjandrum disintegrated into a flaming pile of wreckage on the beach, so did any hopes of it ever seeing real battlefield usage.