The experiments have been made in two series. In the first, the effect of forebody 

 length-to-diameter ratio (L/D) was investigated by measuring the resistance and transition 

 locations of four models with forebodies having different bow entrance L/D's and a fixed 

 bow prismatic coefficient of 0.667. The data obtained in this series were also used in 

 developing the new method of analysis given in Reference I. For completeness, most of the 

 results from the Series 1 experiments, reported in Reference 1, are repeated. 



In Series 2, the effect of very large values of bow prismatic coefficient on resistance was 

 investigated. Properly shaped blunt forebodies could create strong favorable pressure gradients 

 in the forward regions of the forebodies where transition could be expected to take place at 

 full-scale Reynolds numbers. These pressure gradients would extend laminar flow further aft 

 when compared with flow on more conventional forebodies, possibly producing a more 

 favorable operating environment for sensors, in the bow region. In Series 2, five blunt fore- 

 bodies were investigated, including two that were flat faced. 



MODELS 



To conduct the resistance experiments, nine models were constructed, all bodies of 

 revolution. Each model consisted of a forebody, parallel middle body, and fixed afterbody: 

 see Figure 1. Seven of the models had rounded forebodies, and two had flat faces. The 

 volume and the maximum diameter of ail models were kept constant. In this section, the 

 method used to generate forebody shapes, the selection of the forebodies, and the construction 

 of the models will be discussed. 



GENERATION OF FOREBODIES 



Rounded Forebodies 



Six of the rounded forebody shapes were developed using the Granville family of 

 quadratic polynomials' ; the seventh "rounded" forebody was hemispherical in shape. The 

 nondimensional offsets of the polynomials and the hemispherical shape are given by the 

 following two equations 



McCarthy, J.H. et al., "The Roles of Transition, Laminar Separation, and Turbulence Stimulation in the 

 Analysis of Axisymmetric Body Drag," Eleventh Symposium on Naval Hydrodynamics, London (1976). 



2 Granville, P.S., "Geometrical Characteristics of Noses and Tails for Parallel Middle Bodies, " NSRDC 

 Report 3763 (Dec 1972). 



