Transmission mechanism for extension and retraction of ceiling propeller of low-altitude civil rotorcraft capable of vertical takeoff and landing

The invention provides a transmission mechanism for extension and retraction of a ceiling propeller of a low-altitude civil rotorcraft capable of vertical takeoff and landing. The transmission mechanism simply achieves extension and retraction of the ceiling propeller, adjusts the length of the ceiling propeller, adapts to normal takeoff of the low-altitude civil rotorcraft well, and reduces air impacts on two wings and the body of the aircraft when the low-altitude civil rotorcraft flies normally or enters a warehouse. The transmission mechanism comprises a base blade holder and is characterized in that base blades are arranged on the base blade holder and are sleeved with end blades; adjusting screw tubes are installed in the base blades; adjusting bolts matched with the adjusting screw tubes are arranged on the end blades; the adjusting screw tubes are connected to driven bevel gears; the driven bevel gears are meshed with a first transmission bevel gear; the first transmission bevel gear is connected to a transmission mandrel; the other end of the mandrel is connected to a second transmission bevel gear; a spline shaft is arranged corresponding to one end of the second transmission bevel gear and is sleeved with a sliding bevel gear; and the sliding bevel gear is meshed with the second transmission bevel gear during movement and is connected to a motor shaft and a clutch mechanism.