| A research effort has been undertaken to investigate critical aspects of launch vehicle performance as affected by variations in specific launch vehicle parameters. The major portion of the study involves liquid propellant systems. However, since solid propellant systems also play a role in today's launch systems, a representative solid-propellant launch vehicle has also been analyzed. The research undertaken determined that the payload capability of a space launch vehicle, or, conversely, the vehicle total liftoff mass, is highly sensitive to the manner in which the space launch vehicle is staged. The research has led to the development and programming of a model for determining optimum staging relationships for given mission requirements. The research then utilized this optimum staging algorithm as a means of computing the sensitivities of the vehicle's payload and liftoff mass to variations in the vehicle's key propulsion and related performance parameters. It has been seen that significant gains in payload weight can be achieved through modest to substantial changes in specific impulse and structure factor. As an example, for a four-stage solid propellant space launch vehicle, and using the above tables, a 33% gain in payload weight can be achieved by increasing specific impulse by only 5%. As a second example, for a two-stage liquid-propellant launch vehicle, and using the above tables, a 41% gain in payload weight can be achieved through an increase in specific impulse of 10%. |
