Billy inspects a Hellstorm Fireball. (TV: Delta and the Bannermen)
Hellstorm Fireball engines were high technology devices used in space cruisers. They were capable of warp 5 in a good tailwind.
Nostalgia Tours converted a space cruiser with a Hellstorm Fireball engine to give it the appearance of a 1950s tour bus. When it crashed into a satellite, the Quarb crystal powering the engine was damaged and Murray accidentally broke the Doctor's replacement. He grew another in twenty-four hours with the TARDIS' thermo-booster and the engine was repaired. As it prepared to take off, the bus was destroyed by the Bannermen. (TV: Delta and the Bannermen)
