The Ames 40 by 80 foot wind tunnel and its staff are primarily devoted to research. When it is in the national interest, however, development testing can be done. Approval for such testing for military projects requires the request of the cognizant branch of the DoD. The wind tunnel is staffed and operated by NASA. This guide provides information to aid in the preliminary design of models for use in this wind tunnel. The information presented is subject to change without notice due to the continual evolution of techniques and test equipment. It is essential that the staff of the Large-Scale Aerodynamics Branch (LSAB) at Ames Research Center be consulted early during the planning of tests and designing of models. In no case should model construction be started before such consultation. Special devices, such as equipment for remote operation of model or airplane engines and controls, are not enumerated in this guide. The LSAB staff should be consulted concerning any special needs.