Sure-shot igniters were also a component of a multi-staging technique using flash bulbs from old-school camera flash cubes. This technique was very useful for reliably igniting upper stages on scale models, where there was substantial distance between stages. The system was built into a payload section as part of the booster stage. A Sure-Shot wick was taped to the side of a flash bulb, and inserted into the upper stage engine nozzle. The flash would be set off by a mercury inertia switch that would close when the model decelerated after booster engine burnout. The flashbulb generated enough heat to set off the igniter wick. Power was usually supplied to the flashbulb via an appropriate sized electrolytic capacitor. A battery was sometimes used, but the modeler would run the risk of having the second stage ignite on the pad if the model was accidently bumped, closing the mercury switch. There were a few work-arounds to this; installing a small external on/off switch in the circuit that could be manually turned on just prior to launch, or an umbilical cord that would allow leaf-type switch contacts to close as the rocket lifted off. Still the best way was to go was the capacitor route. The cap could be charged on the pad just prior to launch. Another advantage of this system was that a regular short delay engine could be used in the first stage for deploying a recovery system, since the model didn't rely on the usually 'series blowthrough' method of upper stage ignition.
The flashbulb system was also useful for reliable cluster ignition.
