Air launch is an incredibly tricky operation. Even something as trivial as a 500 lb. bomb undergoes lots of trials before it is accepted for use. The US Space

Air launch is an incredibly tricky operation. Even something as trivial as a 500 lb. bomb undergoes lots of trials before it is accepted for use. The US Space Shuttle program only ever did glide testing of the orbiter off the back of the 747 carrier. A real launch of an orbital vehicle off the back of an AN-225 would mean serious envelope pushing and would be putting an extremely expensive aircraft at risk every time.