Development of an Environment for Determining Vehicle Mass Properties of a Reusable Booster Design

Abstract

The Air Force Research Laboratory has identified a Reusable Booster System (RBS), consisting of a reusable first stage and an expendable upper stage, as a concept of interest for future U.S. Air Force launch needs. In order to streamline ground operations, a Return To Launch Site (RTLS) trajectory with a runway landing is needed. Studies have shown that reusable first stages have less desirable trim characteristics throughout their large flight regimes; however, the increased responsiveness and cost benefits are desirable. The trim problem during the glide back to the launch site is non-trivial. In addition to the large flight envelope during RTLS, the propellant burning causes major shifting of the center of gravity to a far aft position. The trim issue needs to be addressed as a multidisciplinary problem early in the design process. An effort was conducted to create an integrated trim analysis and packaging environment for a fully parameterized RBS vehicle. This paper focuses on a component of that environment for packaging and the calculation of vehicle mass properties of an RBS design. The final product integrated dozens of Mass Estimating Relationships into a relationship repository within the integrated trim analysis andpackaging framework. Example trade study results are presented showcasing the packaging capabilities of the completed environment. Nomenclature AFRL = Air Force Research Laboratory AFWAT = Air Force Weights Analysis Tool CG = center of gravity ELV = expendable launch vehicle HLV = hybrid launch vehicle MEL = main equipment list MER = mass estimating relationships OML = outer mold line PMF = propellant mass fraction RBS = reusable booster system RCS = reaction control system RTLS = return to launch site TPS = thermal protection system