Air-support concept for a large telescope

The advantages that accrue to a large telescope mounting concept in which air pressure is used to support over 250 metric tons, in the case of a 7.5-m diameter primary mirror, are discussed. This air support concept obviates the conventional external dome and accomodates such comparatively long focal ratios as those in the f/3-4 range, thereby yielding a less limited field and superior optical figuring and collimation. The telescope is housed within a sphere, and manipulated from below in either an altazimuth or equatorial mode. The cost of a telescope of this design will compare favorably with other designs recently proposed in the literature.