the company requested that a Spirit of Ecstasy be fixed to the chassis and that the characters avoid referring to the brand with abbreviations such as "Rolls". Scale explosions were created using substances such as fuller's earth, petrol gel, magnesium strips and Cordtex explosive. They were originally filmed at up to 120 frames per second (f.p.s.), so that when slowed down to the regular 24 f.p.s., their apparent magnitude and length would be increased. Gunpowder canisters were ignited to create rocket jets. The wires that electronically fired the rockets also allowed a member of the crew, holding a cruciform and positioned on an overhead gantry, to "fly" the model over the set. By far the most unwieldy model was Thunderbird 2, which Meddings remembered as being "awful" to fly. A combination of unreliable rockets and weak wiring frequently caused problems: should the former be slow to ignite, the current quickly caused the latter to overheat and snap, potentially damaging the model and even setting fire to the set. Conditions above the studio floor were often dangerous due to the heat and smoke. Although many of the exhaust sound effects used in the series were drawn from an audio library, some were specially recorded during a Red Arrows display at RAF Little Rissington in Gloucestershire. By 1966, Meddings' commitments were split between Series Two and Thunderbirds Are Go. While Meddings worked on the film, camera operator Jimmy Elliott assumed the responsibility of directing the TV effects. By this stage, the basic frame of Thunderbird 2 had been damaged so many times that the model had needed to be rebuilt from scratch. Meddings was displeased with the result, reflecting that the replacement was "not only the wrong colour, it was a completely different shape ... I never felt our model-makers managed to recapture the look of the original." Critic David Garland suggests that the challenge facing the Thunderbirds effects department was to strike a balance between the "conventional science fiction imperative of the 'futuristic'" and the "seeping hyper-realist concerns mandated by the Andersons' approach to the puppets". Thunderbirds has been praised for the quality of its effects. Jim Sangster and Paul Condon, writers of Collins Telly Guide, consider the model work "uniformly impressive". To Paul Cornell, Martin Day and Keith Topping, writers of The Guinness Book of Classic British TV, the effects are "way beyond anything seen on TV previously". Impressed by