As a result, the tail of the rocket normally remains at the rear during flight. The passing air twists the tail of the rocket until it's at the rear of the moving object. A rocket engine works by ejecting stored material. It pushes on this material to make the material accelerate and the material pushes back on the engine. If the force that the ejected material exerts on the engine is upward and greater than the rocket's weight, the rocket will accelerate upward.
Most rocket engines are chemical engines.
They combine stored chemical fuels to produce hot, high-pressure gas. Gases always accelerate toward lower pressure, so the high-pressure gas moves faster and faster as it rushes out of the nozzle. By the time the gas leave the engine completely, it's traveling several thousand meters per second. A liquid fuel rocket has an exhaust velocity of about 4,500 meters per second or about 3 miles per second. The gas pushes back and propels the rocket upward.