Introduction T HE purpose of this study is to determine the benefits of airlaunching expendable or reusable launch vehicles (LV) by using quantitative methods. Air-launch vehicles consist of at least two stages, a carrier aircraft and a rocket-powered LV. The carrier aircraft can be either subsonic or supersonic capable and can even include balloons. Air launch is one of the leading concepts that can meet today’s launch requirements of both responsive and low cost. Previous work in this area has identified nonquantitative benefits and drawbacks of air-launch methods.1 In this Note, many different air-launch scenarios associated with different release, launch conditions, and vehicle aerodynamics are modeled and simulated using trajectory optimizations. The trajectory optimization is conducted using POST, a numerical integration program based on the three-degree-of-freedom equations of motion of a flight vehicle.2 More than 160 simulations were conducted in which launch altitude, speed, and flight-path angle were varied, and the effect of adding a wing was also modeled.