Vertical Motion Due to Pitch 



CENTER OF 

 PITCH 



U-FRAME 

 (ROPE-SUSPENSION POINT) 



p = -^(44)^ + (23)^ = 49.7' 



23 



<t>o = fan' = 27.6P 



44 



Yp = p \sin ( <i>p + <i> q) - sin, <P q 

 from Section G, for sea state 3, 4>p = +pP 



Yp = 49.7 sin (27.^ + 2P ) - sin 27.^ 



Yp = 1.54 ft. 



Computations 



The curves shown in figures D-1 through D-4 were plotted using data generated by a 

 computer program based on the above analysis. Table 2 shows a typical set of calculations 

 for plotting line tension versus line length curves. 



CONCLUSIONS AxND RECOMMENDATIONS 



The results of the dynamic analysis performed in this study indicate that 4y2-inch cir- 

 cumference Plimoor nylon rope will be suitable for lifting ALVIN in sea states less than 3. 

 For this condition, lift line loads will not exceed 15,000 pounds for line lengths greater than 

 150 feet. NAVSEC evaluation of the 4V'2-inch Phmoor rope indicates that loads of this mag- 

 nitude are permissible under the short time operating conditions anticipated in this applica- 

 tion. A 15,000 pound maximum load provides a factor of safety of 3 based on the breaking 

 strength of 45,000 pounds. 



Based on the analysis performed, it is recommended that a load cell (tensionometer) be 

 provided in the rope system to monitor the lift line loads at all times since it is apparent that 

 severe resonant conditions could develop under the right conditions. The load cell used 

 should be sensitive enough to measure transient dynamic loads as well as static tension. 



73 



