A pneumatic
landing gear retraction and extension
system with mechanical
sequence control and rapid unloading capability includes: a
gas supply mechanism, an unloading valve, and a retraction and extension mechanism; the unloading valve has a left-position functional state and a right-position functional state; when the unloading valve is in the left-position functional state, the outlet of the unloading valve is connected to the inlet; when the unloading valve is in the right-position functional state, the outlet of the unloading valve is connected to the exhaust port; when the retraction and extension mechanism needs to be deployed, the unloading valve is in the left-position functional state; the
gas supply mechanism supplies gas to the unloading valve, which enters the hatch retraction and extension mechanism and the positioning trigger valve of each retraction and extension mechanism; when the gas drives the hatch retraction and extension mechanism to deploy to the position, the positioning trigger valve switches to the conducting state, delivering gas to the
landing gear retraction and extension mechanism to drive it to deploy to the position; when the retraction and extension mechanism is deployed to the position, the unloading valve is in the right-position functional state; the residual gas in the retraction and extension mechanism is discharged to the
atmosphere through the exhaust port of the unloading valve, realizing rapid pneumatic unloading.