44 RECENT PROGRESS WITH THE ACTIVE TYPE 



is also the case with submarines ; then again the condition where a limited power sup- 

 ply is available for spinning the gyro or gyros and handling the equipment. 



Inasmuch as the roll quenching power of the gyroscope varies as the square 

 of its diameter and only directly as its speed and weight, and inasmuch as another 

 factor, i. e., the power required for spin at the higher rates, varies almost directly 

 as the cube of the peripheral velocity, it will at once be seen that where ample 

 space is available and the matter of weight is not critical the rotor and spread of 

 bearings may be so adjusted as to require a minimum of power for maintaining the 

 spin of the wheel for a maximum of gyroscopic moment; and vice versa where only 

 a limited space and weight are permissible and an abundance of power available, 

 a small gyro spinning at higher velocity may be utilized for developing compara- 

 tively large stabilizing moments. 



As is characteristic of western enterprises, it has come to pass that the first 

 commercial gyroscope stabilizing equipment to be installed has been placed upon the 

 beautiful little yacht Widgeon plying on the Great Lakes, owned by Mr. H. M. 

 Hanna, Jr., of Cleveland, Ohio. This was placed in service in the autumn of 191 5, 

 and is of the full active type. The characteristics of the Widgeon, after some in- 

 vestigation, were determined to be as follows: — 



Displacement 165 tons 



Metacentric height 1.75 ft. 



Period of roll, over and back 4.75 sec. 



Water line length 120 ft. 



Water line beam 18 ft. 2 inches 



Total submerged amidship section 80 sq. ft. 



For this ship a gyro was selected giving a K^W 2,700 lbs. -ft. ^ 2,750 revolu- 

 tions per minute, roll quenching power per increment, 5°, the gyro rotor, shaft and 

 armature weighing 2,150 pounds. 



The space selected as best suitable under all conditions for the location of the 

 plant was on deck just abaft the stack, where it has been surrounded by a cabin- 

 like housing (shown in process of building in Fig. i, Plate 30), conforming with 

 the superstructure of the yacht, provided with windows permitting full observa- 

 tion of all of the movements and oscillations of the gyro, which are known to be 

 more or less unusual and interesting in character. The total weight of the equip- 

 ment is about I per cent of the displacement. 



This yacht was looked upon as being a very free roller and has been reported 

 to have rolled through an arc of 70° or thereabouts. The gyroscopic roll recorder 

 (see Fig. 18, Plate 36) afterwards employed in this ship showed, however, that 

 the estimate of roll from the ship's clinometer may have exaggerated this arc to 

 some extent. After installation it was found that when the gyro was thrown "off" 

 a free roll of from 24 to 40° of total arc was quickly developed while running in the 

 trough of the sea, and when the gyro was thrown "on" this was quickly reduced 

 and held at 2 or 3°. 



