86 SESSION OF FRIDAY MORNING, NOVEMBER 12, 1920. 
THIRD SESSION. 
FripaAy Morninc, NOVEMBER 12, 1920. 
The Acting President, Mr. Homer L. Ferguson, called the meeting to order at 
10.30 o'clock. 
Actinc PRESIDENT :—The first paper on the program this morning is No. 6, entitled 
‘‘Comparative Tests of Bilge Keels and a Gyro-Stabilizer on a Model of the U.S. 
Aircraft Carrier Langley,’’ by Commander William McEntee, of the Construction Corps, 
U. S. Navy, Member. 
CoMMANDER McENTEE:—The paper may be of interest in showing the first 
published results of the experiments carried on with the wave-making apparatus in the 
Model Basin. This apparatus was installed by Admiral Taylor and was almost in work- 
ing condition when he left the Model Basin. In all of our models of real ships we roll 
them in waves, with and without bilge keels, to determine quenching characteristics and 
their stability under rolling conditions. The Langley was formerly the Jupiter, being 
converted for an airplane carrier, and as the airplanes are to land on her deck and to fly 
from her deck, it is highly desirable to stabilize the ship and keep it from rolling, particu- 
larly when the machines are attempting to land on the deck. 
We first made the experiments with and without bilge keels, in the ordinary course 
carried out for all naval vessels. The results are given, as you will see, on Plates 32 and 
33. These do not require much comment, possibly the marked damping effect of a 
bilge keel may seem greater than what is ordinarily to be expected. It may be remarked, 
however, that on this particular vessel there is a very square and full midship section, 
with about, as I remember it, 30 per cent parallel middle body, which offers a very excel- 
lent form for fitting bilge keels. The corners of such a square section are the best pos- 
sible place on which to put the bilge keels, because, in rolling, the velocity of water 
around the corner is very much greater than for vessels of easier bilge; so that, although 
the bilge keel is only 15 inches in depth and 180 feet in length, it has a decided influence 
in reducing the roll. As you will see, in a system of waves which would roll the vessel, 
without bilge keels, over an arc roll of approximately 27 degrees, the bilge keels reduce 
the roll to less than ro degrees; in other words, the arc of roll with bilge keels is about one- 
third what it is without bilge keels. 
Commander McEntee then read the paper. 
CoMMANDER McENTEE:—I had some moving pictures taken of the experiments as 
they were carried on. Unfortunately the views are not labeled and have no legends on 
them to indicate when the stabilizer was thrown in and when it was thrown out. When 
you see the pictures on the screen, you will see the model rolling and will see it 
stop again. That is not due to the fact that it moves out of synchronism with the 
waves. When you see it stop, it means that the stabilizer has been thrown in, and when 
it starts rolling again the stabilizer has been released. The picture should have had a 
legend to indicate that particular fact. 
The moving pictures were then shown on the screen. 
