Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1898-01-13

Models to Determine the Possible speed of
ships.


ships.
II has cost the government over
So 600, 600 in speed premiums TO verify
by performance tho calculations Of the
designing bureaus of the Navy Depart
ment, says tine New York Sun, but
hereafter, by means of AN experimental
model tank at the navy yard. Washing.
ton, the possibilities of the heaviest OF
our future ships may be determined to
a nicely. The last regular session of
Congress completed total provision OF
S1C0, 900 for the construction OF this
experimental plant, and by industrious
work the establishment has already
been hastened halfway to completion.
Easily within a year the place will be
ready for practical application.
Based upon the Investigations OF the
late DR.. William Froude of England, it
is known that the performance OF a
model bears mathematical ratio 10
the performance of full-sized ship,
and by multiplying the known tunG-
tions OF tho miniature by its ratio to
the proposed craft the possibilities and
peculiarities of the contemplated vessel
arc predetermined beyond question.
The application OF the model tank APP
plies as we'll TO merchant craft as to
naval vesselH and il is tho purpose of
the Navy Department to place tho es
Enlistment at the disposal of civilian
and commercial undertakings.
Tho completed structure will consist
primarily Of a concrete lined basin sur
rounded by one story brick building,
which is 5urmounted by a stsel -trussed
roof Of an approved pattern. the main
basin is $40 feet long and 40 feet wide,
and will have uniform depth Of II
fat. At ono end will he a narrow, shoal
extension, 10 feet long and q feet vice,
from which tho trial runs will DO
started, anl at the other end, one "a
feet long and feet wide, into which
the mudels will lie carried upon the
completion Of the runs.
On tho innur lip, so TO speak. OF the
main foundation of concrete, will rest
the tracks upon which the carriage will
travel during the runs, These tracks
OF which there are two on each eide OF
the basin, extend from end to and Of
tho building, and are of the honvirst
railroad type, and are so fastened to
the foundation us to maks them as
nearly rigid as possible The object of
this is to obtain surface over which
the carrisgo-whiCh spans the basin
and tows tho models may be run at
high speeds and with the least amount
of iar.
The towing carriage is also rigidly
constructed and is driven by four
electric motors run on tho trolley sys.
tom. Two will he needed for runs at
speeds from 10 to Il knots, while all
four will he required from that up TO
the maximum of 20 knots. 1t may be
stated bers that a 20-knot run on the
part OF q model is the correlative of a
speed of perhaps 40 knots or more in
the contemplated craft.
In starting the experimental runs it
will be needful, in utilizing the whole
length Of the deem main basin, that the
carriage with the model shall attain the
full speed of the intended tBst by the
time it energies from the extension at
the starting end, otherwise the length
of the runs, especially at high speeds,
would be materially reduced. To this
ond ample power will be provided to
overcome the inertia of the heavy car
riage, which when once in motion, will
be kept at uniform speed by the ex-
penditure of very little power--its own
weight contributing to that end while
absorbing whatever slight vibration
may be present.
Tine dynamometer for measuring the
distance OF the models, together With
the apparatus for recording the results
and the necessary fixtures and electri.
cal arrangements required, are grouped
on platform at the centre OF the car.
riRge.
In addition to these more simple OK
perimentH arrangements will be PRO.
vided for testing the functions or quail
ties Of the models; the etlecta of pro.
pellers OF various sorts ana ut different
speeds, and their relations to the form
of the hull about the stern where the
water runs in to the Screws; and also
to tell what proportionate parts of the
| total resistance Of the model 10 due to
| friction Of the under water surface,
what to wave resistance and what to
eddies.
The models to be experimental upon
| will BIZ as nearly as possible of uni
| form length OF 20 feet as an even scale
proportionate to The full-sized craft
will allow, They will be of pine wood.
accurately cut by q special machine
from the lines of the proposed vessel,
and then carefully measured and
checked before being launched into the
basin. They will then be prepared in
the balancing hRsin, prior 10 starting,
| and nicely ballasted sO 10 represent
accurately the Intended craft when she
is ready for her trial.