LAUNCHING DATA FOR A BATTLESHIP. 99 



After edge of rudder at start, up from intersection of pro- 

 longed keel line and water, about 9 ft. 



After perpendicular to after poppet bearing on ways 66 ft. 



After perpendicular to after poppet bearing on ship 78 ft. 



Forward perpendicular to forward end of sliding ways. . 44 ft. 



Forward perpendicular to center of fore poppets ' 59 ft. 



Means for distributing pressure at fore poppets Rocker formed as a seg- 

 ment of a trunnion 



PRESSURE^ VELOCITY, COEFFICIENTS^ ETC. 



Total weight on ground ways 12,435 tons 



Initial pressure per sq. ft : 2.82 tons 



Maximum pressure per sq. ft. over ground way ends 5.3 tons 



Center of gravity forward of center between perpendiculars 7.9 ft. 



Distance traveled to calculated pivoting 459 ft. 



Distance traveled to observed pivoting 560 ft. 



Distance traveled from calculated pivoting to end of ways 181 ft. 



Calculated buoyancy at pivoting 8,875 tons 



Pressure on fore poppets at pivoting (neglecting buoyancy 



of packing) 3,090 tons 



Pressure per sq. ft. under fore poppets at pivoting 14-05 tons 



Pressure per sq. ft. on projected area of trunnion segment 



at pivoting 14.85 tons 



Distance traveled to bring center of gravity over end of 



ways ; 410 ft. 



Depth of water over ends of ways (actual corresponding to 



5 ft. 10 ins. tide) 9 ft. 6 ins. 



Least excess of calculated moment to prevent tipping 52,200 ton- ft. 



Static drop of vessel where poppets leave the end of ground 



ways 6 ft. 4>4 ins. 



Average velocity first 100 feet (5.8 ft. per second) 3.3 knots 



Maximum velocity (23.6 ft. per second) Nearly 15 knots 



(Ship hung 2 to 3 seconds and then started slowly without 



application of rams or other means.) 



Travel before rudder entered water, about 25 ft. 



Travel to point of maximum velocity, about 100 ft. 



Time to point of maximum velocity 17-25 sec. 



Travel to point of drop, fore poppet at end of ways, about. 640 ft. 



Time to point of drop, about 41.6 sec. 



Coefficient of starting (sticking) friction, about 0.0575 



Coefficient of friction, average first 50 feet, about 0.026 



Coefficient of friction and resistance, average first 100 feet, 



about 0.016 



