You can use a double-acting cylinder as a single-acting. Simply use a 3-way solenoid and only supply air to the bottom of the cylinder. Leave the top air port of the cylinder open (or optionally install an exhaust muffler into open port as shown in the image).
The weight of the prop or mechanism is responsible for pushing the cylinder shaft back down.
Running a double-acting cylinder as a single-acting makes it very fast. This makes it a great option for simple pop up props.
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