ON A MODEL OF THE U. S. AIRCRAFT CARRIER LANGLEY. 93 
swings. So to bring out the facts in the case so that we can make proper comparisons, I 
herewith submit a substitute plate, which I have denominated Plate 4o. In addition 
to the curves of Commander McEntee’s Plate 32, I have added four other curves, three of 
which are in dotted or broken lines. Here we have introduced curves where the ship is 
released at twice the angle period. The dotted line at the extreme left shows the real con- 
tribution of the stabilizer as compared with the bilge keels, because here in two and one- 
half swings the roll has been extinguished completely instead of requiring forty swings as 
with the bilge keels, and this with the boat heeled to an angle of 2114 degrees instead of 
11% degrees. The dotted line 1A shows the contribution of the bilge keels when the 
model is released at 2114-degree heel, showing considerable roll after seventy swings. 
But the most interesting comparison on this sheet is the one now to be referred to. 
If we turn to Plate 36, we find that the eccentricity of the wave-maker was gradually in- 
creased from 4-inch eccentricity to 5, 6 and 7 inches. When the wave-maker was at 6 
inches the model rolled, without keels, through 48% degrees, and at 7 inches it rolled 
through 43% degrees owing to a trifling difference in synchronism in the action of the 
wave-maker with the natural period of the model. Now let us see what would have 
happened with the curve on the bottom of Plate 36 had we been depending on bilge keels 
instead of the stabilizer. A very excellent clue to this is found on Plate 34. Here we have 
the wave-maker working at only 3-inch eccentricity, giving the model 26.4 degrees roll 
without bilge keels; with bilge keels, 9.6 degrees roll, but under practically complete con- 
trol with the gyro-stabilizer. 
Let us now apply these same functions to the bottom curve of Plate 36. Here we see 
what the stabilizer can accomplish from a heel of 2134 degrees, this constituting the solid 
line to the left, marked ‘‘Exp. No. 3.’’ Compare this now with the upper broken line on 
the sheet, which represents the contribution of the bilge keels under the same conditions. 
Here we find that the ship would roll continuously, as it does in the upper curve of Plate 
34, but through an angle of something like 16 degrees (heel of 8 degrees +) continuous roll. 
This emphasizes the fact that with the gyro-stabilizer we are enabled to secure vastly 
more complete results without bilge keels, saving all the power that represents the drag 
due to the keels, which istcontinuous and present in calm weather as well as rough. 
In what marked contrast this stands to what the stabilizer does is shown in the full 
line to the left on the plate, marked “Exp. 3.”’ In both of these cases we must remember 
the storm is still raging to the extent of rolling the ship between 43 and 48 degrees, and 
instead of the curve of a 19-degree uniform amplitude passing off the sheet at nearly 10 
degrees, we see in the full line that within three swings practically it has completely 
stabilized the ship. 
You understand that in all the model experiments with the stabilizer the keels 
were absent, just as we have it now on the more recent ships we are stabilizing; of 
course the bilge keel is, like the poor, always with you, in calm weather as well as rough 
weather, and such losses as it entails in service are always there. 
Interest again attaches to Plate 37. You will find at the bottom of paragraph 3 
and also the second line of paragraph 8 that the stabilizing moment was operated 
at 20 pound-feet. This was pitted against artificially impressed rolling moments 
described, which were very much in excess of the quenching moments. When one and 
one-half times, shown in the first curve, Plate 37, stabilizing was very complete, which 
was also true when the moments were increased to practically twice (39 as to 20), 
although it took the gyro longer to subdue the rolling, and only when the rolling moments 
