Complex sentence: Ejector seat parachutes made with ripstop are woven with an elastic like fabric so that they stretch to allow more air to pass through them at high speed, then as they slow up the weave closes and acts like a normal parachute.
Split into simpler sentences: Ejector seat parachutes made with ripstop are woven with an elastic like fabric so that they stretch to allow more air to pass through them at high speed. Then as the ejector seat slows, the weave closes and acts like a normal parachute.