The Soviet Union redefined heavy bombers in 1930 with the introduction of the Tupolev TB-3, a four-engine behemoth so large that it could serve as a mothership to five little fighters, which could be released in flight and even hooked back onto the aircraft in order to refuel.

A TB-3 once did manage to take off with four fighters attached, then joined up with a fifth while circling the airfield, with a combined nine engines going. Then all five fighters were released at once. “The thing about events like that is, you always wonder how they entered the flight in their log books afterwards,” writes James Gilbert in The World’s Worst Aircraft. “I mean, if you were the pilot of one of the fighters, you could hardly log the take-off because you hadn’t made it, except as a passenger. But how can you log a landing with no prior take-off?”

The whole contraption, known as Vakhmistrov’s Circus, saw some early wartime service, but it was too complex and vulnerable to be adopted widely. Today it’s a historical curiosity.