|MadSci Network: Engineering|
You don’t need anything as complicated as a motor if all you wish is to move the flap from the closed to open position. I motor might be used if there was a need to locate the flap at various intermediate positions much as is done with a damper in an air stream. What you need is called a “Solenoid.” A solenoid is an electrical to mechanical transducer [I love that word. I just means “changer.”] that converts electrical current to mechanical motion. It is just a coil of wire with a hole in the center. An iron bar is placed in that hole and held partially extended out of the hole by a weak spring. When the coil is electrically energized, its magnetic field pulls the bar into the coil, thus creating the mechanical motion that can be used to open your light-weight flap. Solenoids come in all sizes, all voltages, and either push or pull. What you need would be small, and probably energized with a battery and should be available from any electrical or electronic supplier. You could refer to the manufacturer’s data to determine the answers to your other question, but that would only tell you the maximum values of current, etc. that would be needed when the solenoid was used at it’s highest load conditions. When not fully loaded, those values depend strictly on the load, and if they are really necessary to know, would be determined by test. You set up the operation configuration and measure the current, etc.
Try the links in the MadSci Library for more information on Engineering.