Difficult to find a suitable package. While any of these flame detectors will work if properly configured, the infrared transistor is the most popular and easiest to use. You can stack detectors vertically to cover the range of candle flame heights. Be prepared to adjust for the background level of the walls the day before the contest. Flame Extinguisher Real-world practicality is not a requirement.
Most robots use a fan, either a bare propeller or a small, self-contained unit.
The fan's efficiency depends on its nearness to the flame. If you decide to blow the flame out, make sure you can do it from 12 inches away, the maximum distance allowed. If you use water, add a fire retardant. Many squirters don't put enough water on the flame. A pump from an auto windshield washer works well.