for scopes of 400 and 200 feet where the average differences are about 6% and 



8.7% respectively. 



The relationships between f (<(>), f.(<t>) and C have been discussed previously. 



n t K 



With respect to the problem of fitting predicted-to-measured configurations 

 another factor should be considered. In this methodology the term C accounts for 

 the effect of Reynolds number on both the normal and tangential components of 

 hydrodynamic force. However, it should not be expected that the Reynolds number 

 effects are physically the same for the normal component at steep cable angles 

 where pressure drag predominates and for the tangential component at shallow angles 

 where frictional drag predominates. The final curve fits shown in Figures 6 and 

 7, therefore, reflect a compromise in the expression of C with Reynolds number. 



Ribbon represents a type of "fairing" unlike streamlined rigid fairing in 

 that the geometry changes with speed and with cable angle inclination. It has 

 been observed that at an angle of the cable 90 to the flow, the ribbons stream 

 out normal to the cable axis. At shallow angles, the ribbons have been observed 

 to lay down along the trailing edge of the cable. In addition to cable angle, 

 intuitively such factors as ribbon material stiffness, percent cable coverage, 

 and method of attachment are judged to influence the detailed geometry of the 

 ribbons and therefore the hydrodynamic loading. Some insight into this is given 

 in Appendix A. However, primarily because of a lack of knowledge of how to scale 

 the material stiffness factor, caution must be exercised in applying these loading 

 functions to a cable of significantly different diameter. Scaling should not be 

 attempted outside of the Reynolds number range covered in these tests. 



20 



