The invention discloses a liquid
rocket engine airtight clamp and a using method thereof. The clamp comprises a
handle, a large nut, a jacking hand wheel, a supporting disc, a long pull rod, a short pull rod, a spring, an air inlet
pipe, a sealing disc and a turning plate. When the airtight clamp enters the engine, the turning plate is in an inclined state, after the turning plate completely enters the
throat part of the engine, the
handle is pulled to enable the turning plate to be in a state perpendicular to the axis of the engine, and the turning plate is clamped above the
throat part of the engine; then the large nut is rotated, the sealing disc moves towards the
throat of the engine until the large nut cannot rotate, at the moment, the turning plate and the throat sealing ring on the sealing disc clamp the engine, meanwhile, the supporting disc is attached to the large end of the engine under the action of the spring, and the airtight clamp is fixed to the engine. An external air source is connected with the air inlet
pipe to inflate the inner cavity of the engine. The airtight test clamp can be widely applied to the field of sealing of small
rocket engines, and has the advantages of being novel in structure, reliable in sealing and easy to operate.