A New and Improved Speed and Resistance Meter.
Year: 1890

page_text: Date of Application, 3rd Oct., 1890
Complete Specification Left. 3rd July, 1891-Accepted. 3rd Oct., 1891
PROVISIONAL SPECIFICATION.
A New and Improved Speed and Resistance Meter.
I the undersigned FRANK CAWS, Architect of 60 Fawcett Street Sunderland
do hereby declare the nature of this invention to be as follows:-
The objects of this invention are to measure, with apparatus working within a
minimum of space, the speed and resistance of any mass moving through fluid;
and also to demonstrate experimentally the laws which govern fluid-resistance, and
to render those laws applicable to commercial as well as scientific uses :-for
example, the speed of a proposed ship derivable from a given horse power; or, on
the other hand, the effective horse power due to a given speed, can, by means of
this invention, be ascertained from the ship model made to a small scale and
moving in a short tank and the effect of certain alterations in the lines of ships can
be demonstrated, and the forms of least resistance under given conditions discovered.
The means by which these objects are attained consist of, either
:
1st. Apparatus measuring the decrement of amplitude of an oscillation, the said
decrement being the effect of the resistance in question, the maximum velocity of
the said oscillation being the measure of the speed in question.
In order that results obtained with a small apparatus and in a confined space
may be accurately observed, magnifying instruments or appliances are attached.
The character of the apparatus together with its magnifying attachments may
be very varied; for example, pendulums, springs, or other oscillating mechanisms,
may be employed, either separately or in combination. Also it may or may not
be necessary to employ, in connection with such pendulum or other oscillating
mechanism, a means of imparting to the mass propelled thereby a rectilinear motion
without appreciably hampering or disturbing the curvilinear motion (if it be
curvilinear) of the oscillating motor. The character of such means of converting
curvilinear into rectilinear force may be mechanical or otherwise. Or,
2nd. Apparatus by which the mass to be moved receives from a pendulum,
spring, or from any oscillating, accelerating, or vibrating body or appliance, an
impulse, under the influence of which it travels, until the force of the impulse is
expended on fluid resistance; when, by observing the measures of travel and of
time, and relating the same to the known energy of the impulse, the speed and
resistance of the mass can be found.
For example, a ship model floating, in say a tank or any convenient receptacle,
may receive from a suspended weight, or from a spring, or otherwise, a push or
blow whose energy is expressed potentially by its initial angle of amplitude, and
by its period and by the motor's own mass; and the model after receiving this
impulse may continue to move at a retarding rate until the whole force of the
impulse has been expended in forming and maintaining the series of ever dwindling
and departing waves due to the displacement of fluid mass effected by the model's
notion. Thus, when the energy received by the model from the motor has been
wholly imparted to the waves, and the model consequently at rest; the distance
she will have travelled since parting from the motor in its ratio to the distance
travelled in conjunction of model and motor, and also the time of ship model's

page_text: retarding journey in ratio to the time of her initial or accelerating journey, can,
by means of apparatus, be noted by the observer and will serve him as the measures
of resistance and speed of model. And thus, by the known law which rules the
ratio of the model's performances to those of the full sized ship, the actual speed
and resistance qualities of the full sized ship can be ascertained by experimenting,
in the manner above indicated, upon her small scale model.
Doted this 2nd day of October 1800.
COMPLETE SPECIFICATION (AMENDED).
A New and Improved Speed and Resistance Meter.
I the undersigned FRANK CAWs, Architect 60 Fawcett Street Sunderland do
hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
The objects of this invention are to measure, with apparatus working within a
minimum of space, the speed and resistance of any mass moving through fluid; and
also to demonstrate experimentally the laws which govern fluid-resistance, and to
render those laws applicable to commercial as well as scientific uses:-for
example, the speed of a proposed ship derivable from a given horse power; or, on
the other hand, the effective horse power due to a given speed, can, by means of
this invention, be ascertained from the ship model made to a small scale (or
otherwise) and moving in a short tank (or otherwise); and the effect of certain
alterations in the lines of ships can be demonstrated, and the forms of least
resistance under given conditions discovered.
The means by which these objects are attained consist of, either
1st. Apparatus measuring the decrement of amplitude of an oscillation, the said
decrement being the effect of the resistance in question, the maximum velocity of
the said oscillation being the measure of the speed in question.
In order that results obtained with a small apparatus and in a confined space
may be accurately observed, verniers, or any magnifying instruments or appliances
may be employed. Also self registering or automatic means of obtaining
experimental measures of decrement may be resorted to.
The character of the apparatus may be very varied; for example any oscillating
mechanism such as pendulums springs or other vibrating instrument means or
appliance may be used, either separately or more or less combinedly.
Also it may or may not be necessary to employ, in connection with such pen-
dulum or other oscillating or vibrating motor, a means of imparting to the ship
model, or to any mass propelled by such motor, a rectilinear motion, without
appreciably hampering or disturbing the curvilinear motion (if it be curvilinear)
of the said motor. Such means of converting curvilinear into rectilinear motion
may be purely mechanical, or electro magnetic, or electrical, or of a combination
of these means, i.e. of all or of any of them, or otherwise.
The following example will illustrate one of the many ways in which this
invention can be operated. See drawing.
A simple natural pendulum (M) hanging above the model of a ship (D) floating in
a tank is fitted with projecting arms or trunnions (AA) which as the pendulum swings
move upwards or downwards in the vertical slots of rowlocks (R R) fitted screw
clamped to the gunwale of the model. The slots are knife edged and moreover the
trunnion arms are inclosed with little friction sheaves or runners whose grooved
rims run up and down on the knife edges of the slots so minimising friction as the
ship model moves horizontally to and fro along the level water while the pendulum
motor simultaneously describes its arcs of swing.
Immediately alongside of the pendulum string and stretching-along from end to
end of the tank close above the model is the measuring staff (J), fitted with two

page_text: sliding verniers (FF). When the pendulum bob is hanging plumb it is opposite the
zero mark (F) on the measuring staff.
The ship and pendulum are drawn backwards and fastened back so that the
string of pendulum barely touches a suspended needle (X) which hangs from a
short arm (Y) standing square out from the initial or starting vernier which has
been set to some definite distance from zero on the measuring staff.
The other vernier has a similarly projecting short arm (Y) from which a
needle (X) likewise hangs horizontally sustained by two little slings of thread.
This other is the final or arrival vernier. It is placed at some definite distance
from plumb line zero on the opposite side from the starting vernier so that the
two vernier needles stand out ready to catch the string of the pendulum, and facing
each other at nearly equal distances from the plumb line zero.
By means of a leash line (L) one end of which is fastened to the model, or to the
pendulum bob attached by rowlocks-connection to the model; and the other end
of which is fastened to a winding capstan planted on the end of the tank, the ship
and pendulum together are wound or towed backwards till the pendulum string
exactly touches, and no more than touches, the initial vernier needle.
Then the leash line is burnt and the model propelled by pendulum shoots forward
and, if the final vernier is not too far away from plumb line, the pendulum string
will come in contact with the suspended needle of that final vernier and cause it
to oscillate in its slings. If the final vernier be placed, after repeated experiments
by trial and error, in that exact position at which the pendulum string starting
from the given position of the initial needle, swings forward just and only just far
enough to barely touch the final needle, it will be found that the initial needle is
a little more distant from zero than the final needle is, the difference of distance
being the loss of amplitude due to the resistance.
Now when if a pendulum of lead or some such dense material is employed its own
resistance in one stroke of a small are of amplitude is too infinitesimal to be
observed, and it may be neglected without sensible error of results. That is to say
the whole observed decrement of amplitude may in such case be attributed to the
resistance of the ship, or if the resistance of the bob itself be measurably observable it can
be allowed for.
And thus a measure of resistance is found corresponding to the speed of the
model at the moment of passing vertex.
The actual decrements of amplitude thus observed experimentally are obtained
in tangent measure, from which their value in versine measure is found by ordinary
trigonometrical process.
Let M
D
-
=
Mass of pendulum bob.
Mass of model displacement.
t = Time of half beat of pendulum when towing or propelling ship.

page_text: g M H = Energy potential at initial angle of amplitude.
g M = Energy kinetically engaged at the vertex-moment in propulsion
of MD potential at final angle of amplitude.
-
|g M (H) = Energy kinetically engaged at the vertex moment in pro-
pulsion-of-r expended on resistance during the beat, i.e. during t.
g M (H – h) =P -
t
=
rate of work performed in continually
power engaged
propelling the M + D + at the uniform speed (i.e. vertex velocity S) due
to r, in spite of the continual escape of r's momentum.
That is to say,
only the momentum of M + D is effective, while the momentum of con-
tinually escaping with the wave necessitates the continual supply by P of
fresh momentum, to maintain the r at its constant measure, in order that
the corresponding constant measure of speed (S) may be maintained.
lbs. ft.
MH
1,\
D, neither changes in
M, do not can produce change in
For a given S, and a given model of displacement mass, =
the pendulum radius nor in the pendulum mass,
the E HP.
=
The pendulum radius may be of any convenient length; the longer the radius,
the longer the tank must be, and the larger will be the scale of results.
The above is an outline of one some of the mathematical and dynamical processes
by which the results experimentally obtained from the resistance meter are
translated into useful measure of E HP for given S.
2nd. Apparatus by which the mass to be moved receives, from a pendulum,
spring, or from any oscillating, accelerating or vibrating body, or appliance, or
meaus, an impulse, under the influence of which it travels, until the force of the
impulse is expended on fluid resistance; when, by observing the measure of travel
and of time, and relating the same to the known energy of the impulse, the speed
and resistance of the mass can be found.
For example: a ship-model floating in say a tank, or any convenient receptacle,
may receive from a suspended weight, or from a spring, or otherwise, a push or
blow, whose energy is expressed potentially by its initial angle of amplitude, and
by its period, and by the motor's own mass.
The model, after receiving this impulse may continue to move at a retarding
rate until the whole force of the impulse has been expended in forming and main-
taining the series of ever dwindling and departing waves due to the displacement
of fluid mass effected by the model's motion.
Thus when the energy received by the model from the motor has been wholly
imparted to the waves, and the model is consequently at rest, the distance she will
have travelled since parting from the motor in its ratio to the distance travelled in
conjunction of model and motor, and also the time of ship model's retarding journey
in ratio to the time of her initial or accelerating journey, can-by means of
measuring and timing appliances-be accurately noted by the experimenter, and
will serve him as measures from which the speeds and resistances of models can be
ascertained by properly dynamical processes of translation and calculation.
Having, by either Method 1 or Method 2 as above described, found the model's
speeds and resistances then-by the known law of correspondence between the
performances of the model and those of the full sized ship-the speeds and
resistances of full sized ships can be ascertained.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
A new and improved speed and resistance meter embodying and including new
and improved means and methods of ascertaining the speeds and corresponding
resistances of ships and other solids moving through fluids, substantially as above
herein described and specified.