A growing/shrinking spaceship consists of two spaceships and an accompanying flotilla. The front ship is a wick stretcher that extrudes a wick and the rear end is another spaceship of the same velocity that eventually collides with the end of the expanding wick, but instead of being destroyed by it, ignites the wick so it burns cleanly at a higher speed than that of the spaceships, until it reaches the front spaceship, at which point a new wick is extruded. The wick eventually reaches the flotilla and generates another rear spaceship, starting a new cycle, like a moving oscillator. The population is a sawtooth that oscillates between that of the two spaceships and the flotilla alone, and that of the two spaceships with a fully extruded wick.[1]