Complex sentence: The simulated reentry of the Apollo command module is really a drop from a Lockheed C-5 Galaxy transport aircraft; the astronauts are flown to Hawaii, where they enter the Apollo Command Module, which is dropped out of sight of the recovery ship.
Split into simpler sentences: The simulated reentry of the Apollo command module is really dropped from a Lockheed C-5 Galaxy. The astronauts are flown to Hawaii, where they enter the Apollo Command Module, which is dropped out of sight of the recovery ship.