 Scale explosions were created using substances such as fuller 's earth , petrol gel , magnesium strips and <unk> explosive . Originally filmed at up to 120 frames per second ( <unk> ) , they were slowed down to 24 <unk> during post @-@ production to increase their apparent magnitude and length . Gunpowder <unk> were <unk> 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 <unk> frequently caused problems : should the former be slow to ignite , the current quickly caused the latter to <unk> 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 <unk> in Gloucestershire . 
