The Great Panjandrum
Developed by the British during WWII as a means for clearing obstacles ahead of the D-Day landings, The Great Panjandrum consisted of a large drum stuffed with a ton of explosives and affixed to rocket-propelled wheels. The idea was to ignite the rockets from a platform at sea, and the angled rockets affixed to the wheels would cause them to rotate rapidly, launching the contraption at targets and obstacles onshore, blowing them up and clearing the way for follow on troops who would land hot on the Great Panjandrum’s heels.
The device was supposed to be developed in secrecy in order to spring it as a surprise on the Germans, but testing was conducted on a beach popular with vacationers, so the trials were witnessed by huge crowds. The design’s flaw emerged at the first trial run in 1943: when the rockets were ignited and the device was launched, it made its way up the beach before rockets on one of the wheels malfunctioned, causing the Great Panjandrum to careen wildly off course. The problem persisted with additional trials, as each time it proved impossible to get the rockets on both sides to ignite simultaneously or to keep firing simultaneously.
After weeks of troubleshooting, the developers returned to the beach, this time having affixed a third wheel to the device to increase its stability. That test proved more embarrassing yet, as the device hurtled toward the beach, only to double back and turn back to sea towards the launching craft. In the meantime, some of the rockets had detached from the Great Panjandrum’s wheels to launch themselves at the observers on the beach, whistling over their heads or exploding underwater nearby.
Returning to the drawing board, the Great Panjandrum’s designers worked out the bugs, and figuring that they finally had it under control, conducted a final demonstration in front of a gathering of admirals and generals. As described in a BBC documentary:
“At first all went well. Panjandrum rolled into the sea and began to head for the shore, the Brass Hats watching through binoculars from the top of a pebble ridge […] Then a clamp gave: first one, then two more rockets broke free: Panjandrum began to lurch ominously. It hit a line of small craters in the sand and began to turn to starboard, careering towards Klemantaski, who, viewing events through a telescopic lens, misjudged the distance and continued filming. Hearing the approaching roar he looked up from his viewfinder to see Panjandrum, shedding live rockets in all directions, heading straight for him. As he ran for his life, he glimpsed the assembled admirals and generals diving for cover behind the pebble ridge into barbed-wire entanglements. Panjandrum was now heading back to the sea but crashed on to the sand where it disintegrated in violent explosions, rockets tearing across the beach at great speed.”
Unsurprisingly, the project was immediately scrapped over safety concerns.