The primary focus of this paper is to describe the development of a highly modified aircraft that carries a twenty ton telescope to the stratosphere and then loiters at this desired altitude to act as the observatory platform and dome. When the aircraft has reached its nominal cruise condition of Mach 0.84 in the stratosphere, a large cavity door opens (the dome opens), exposing a large portion of the interior of the fuselage that contains the telescope optics directly to the Universe. The topics covered in this paper include: the relevant criteria and the evaluation process that resulted in the selection of a Boeing 747-SP, the evolution of the design concept, the description of the structural modification including the analysis methods and tools, the aerodynamic issues associated with an open port cavity and how they were addressed, and the aeroloads/
disturbances imparted to the telescope and how they were measured in the wind tunnel and extrapolated to full size. This paper is complementary to a previous paper presented at the 2000 Airborne Telescope Systems conference which describes the challenges associated with the development of the SOFIA Telescope.
For completeness, this paper also provides a brief overview of the SOFIA project including the joint project arrangement between NASA and DLR, a top level overview of the requirements, and finally the current project status.