CHAPTER V 



RESISTANCE TESTS ON SERIES 60 PARENT MODELS 



The five parent models were made to lines drawn out from the new contours and had 

 the numbers and particulars given in Table 2. The lines are shown in Figures 12 through 16; 

 the area curves are given in Figure 17 and the offsets in Tables 3 through 7.* 



The models were made of wax, 20 ft LBP, and towed in the deep-water basin at the 

 Taylor Model Basin, which has a cross section 51 ft wide and 22 ft deep. 



Experiments were made with and without turbulence stimulation. The latter was 

 provided by studs, 1/8 in. in diameter, 1/10 in. high, spaced 1 in. apart along a line parallel 

 to the bow contour, the fore and aft position being controlled by the angle of entrance on the 

 LWL as described by Hughes and Allan. "^^ 



When these series experiments were begun in 1949, the question of turbulence stimu- 

 lation was under intensive study, and its im.portance, especially in full models, had only 

 recently been widely appreciated. At that time, there was no agreement as to the best method 

 of stimulating turbulent flow, and indeed the subject is not satisfactorily resolved even today. 

 Several methods were being advocated, the principal ones being sand strips, struts, trip wires 

 and studs. The Series 57 models were run with sand strips, but these were abandoned in 

 favour of studs for the Series 60 parents and LCB series. The studs were replaced by trip 



wires for the final series of variations in — and — ratios because experience had shown 



B H 



that trip wires gave slightly higher resistances than studs for the full models. Moreover, it 



was hoped that other experiment tanks would in the future use Series 60 as a point of depar- 

 ture for series work, and miost of them used trip wires. In the final presentation based on the 



LB. 



— , — Series, the contours all apply to tests m.ade with trip wires. An account of the experi- 



m.ents carried out to evaluate the different types of stimulation is given in Appendix A. 



The resistance results from the models have been converted to apply to ships of 400 ft 

 LBP and with other dimensions as listed in Table 2. In making this conversion, the ATTC 

 1947 friction form.ulation was used together with an addition of +0.0004 for model-ship correla- 

 tion allowance C ^. The ship values haye been expressed as values of C^^ and are plotted to 



V 

 a base of , in Figure 18. 



*The sections shown in all body plans are equally spaced along the length between perpendiculars, L np. 



(Text continued on page V-10) 



V-1 



