US1774825A - Method of stabilizing ships - Google Patents

Description

Sept. 2, 1930. H. H. Dow

- 7 METHOD OF STABILIZING SHIPS Filed Sept. 1928 STAR.

PORT

I N VEN TOR.

W QM D mm H m a. m w H a HERBERT n."ijowfoniirrnnhnn, iuroiire'lm, As'sIG oRrro marrowCamembert: l

i i The present improvementhas regard Patented Sept.

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method. forreducing the-roll of a ship and has more particular-regard to a 'method of reducing theroll of-a propeller-driven ship. The object of the invention-is'to; provide .a method that will -accomplishthe stated result without requiring the expenditure of excessive energy andthat may be madeto operate automatically; i.- e., be brought into action by initial' rolling movement of the VesSel 'itself. Itiwill, of 'course be undere stoodthat'a stabilizing method of the char-[ actor in' hand may be employed upon anyv which h g a Propeller, drive "and the equivalent o a; yant supPQrt-A" I To the accomplishment of the -'foregoing and o related ends, jthe invention, them-Q con-, sists'of the steps and'mean'shereinafter fully describedand particularly pointed out infthe claims, the annexed drawings and-the following description setting forth in detailcer tain means and one mode ofjcarrying out the invention,- such disclosed means and mode illustrating, howeveig'but one-"of variousways inwhich the principle of the inyention be used. 7

Figure 1 represents steam-driven vesseloutlined'by the broken "line sif A pro v I peller is shown-:at'Rdriven by the 'engineE,

steambeing derived from; the boilers I;

Figure 2 intlicatestoadarger scalea stern view' of: such a-boat e-with propeller-P. f

It is well'known 'thata buo'yantly su 7 ported vehicle such as ashipinzwater;rollsp to port th'en to starboard,-backtoport and so on indefinitely; with a pendulum like motion,

- i. 13., it exhibits a periodic roll.; The forces tending 5 to producefthis rolling movement may notbe verygr'eatrelative to the weight of the ship or the forces employed in drivingthe ship on its way,fbut theapp'lioation is rhythmic and the pendu'lum-like swinger roll of the boat is built up gradually to large proportions by thefp'ersis'tentfiand repeated rhythmic application --of-the said relatively i small forces. The present-invention is designed to utilize forces 'developedl'by' the shipsiengine or motor to resist or neutralize the forces that; thus'te'ndto produce the roll o PANIOFJYLIDLANDZ MICHIGAN, a ooiarora'A'rro1a or MICHIGAN ship -ac'cordingly.-" i A :Since action" andreact-ionare equal and I opposite in direction it follows'thatr halving ,7 I the torque willfalso halve j its reaction upon tillbeinotecl that inoidentally to i'ng by means of. ascrew propeller; 'the'axial n thrust which propels the: boat through the,

water or other medium" in which it is float-C ng azturning moment or torque 1s first; de

veloped; that is,- the: engine which is :fixedly mounted in the ship transmits tothe propeller (or propellers; where more than one is employed) its turningmoment; To increase'i-the rate of revolution of the propeller, increased turning moment ortorqueisrequired'anolthis turning moment or torque may therefore be varied by varying the rate :ofrevol'ution' of the propeller. Thefreaetion; upon theof this turning momentisto cause' -the ship to -list or roll slightlyin a direction opposite I to that in which thetpropelleris being' turned; and-if the rate of revolution be variedthe torque or tu'rning;m oinentfwill vary; and'the tendency of the reaction upon the fship to list it will vary accordinglyfi Similar p lersare used and, as I lfi-ven-in opposite' directions at equal sp d v and are 5 respectively made right and "left hand, then the turning moments or "torques developed by such propellers will beequal the two propellers be varied; the difference and: opposite and will'be neutralized one by o the other so long as the moments 'iemain V V I "equal? :If, howeve'n the relative speeds-of;

v between the altered moments of the port, and

starboard propellers whichnow arenoxlonger equalmay be m'a'deto act at will-toward port or towards starboard-and the ship; and 'doublingthe torque will double its 'reaetion upon "the" ship. 'f Itfollo'ws, further, that given aship floating in-iquiet water' unacte'd' upon'by' outside forces, the

shipmay bemadeto roll rhythmically with p a' pendulumv-like action by*varying ,the rate of revolution of. her propeller or propellers instep with the natural period of oscillation of the-ship,

Based on the foregoing l have discovered I that by varying the {moment oftorque delivered' bytheship tothe'ivvater through'the I propeller orpropellers' in such a way as to augment that torque when such augmentation will resist the forces tending to roll the Y ship and toidecrease that torque. when such torqueisassistingthe forces" tending to roll I the ship, the roll-ingmay "be;measurably reduced orprevented. With a single propeller the rate of revolution and turning moment I .pellers having opposing turningmoments, the same result'is accomplishe'dby increasing the speed and'res ulta'nt torque of that propeller turningin the direction-in which the; ship; tends to roll and 'reducing the speed 'I and. resultant torque .ofthose propellers turning in. a direction opposite .to'that. in which 1 theship tends to roll. It will be understood that such changes in rate. of rotation ofthe propeller; maybe applied to one or all propellerswhether single or plural to vary the I rate of rotation, within suitable limits rhythmically in step with the natural period of oscillation of the ship thus bringing into play changes in the torque between ship and waterjwhich changes will either act'toresist theforces tending momentarily to roll the ship or willreduce the tendency of the ship :to roll by reason of the torque" developed 1 through its propeller orpropellers when'the outside forces act therewith.

. In its simplest application the rate ofrevolution of the engine :Ejin Figure l'will be controlled by varying the steam delivered toit throughthe valveV by opening and closing same to such an'extent, in rhythmic,

' consonance awith the tendency to roll that the engine speed will riseand fall with that tendency causing the torque developed be-:

'tweenthe ship: and the water and its reaction i uponthe ship to rise, and fall in like manner.

7 Such controlmay be manual or automatic.

gyroscopic rotor suitably mounted'in. the ship One forrn ofvautomatical. control would involre sultable 1 mechanical or electrical con.- nect ons and'iactua-tin-g devices between a and the valve V. It is known that a gyro ;-scopic c'ompass may be connected with the steer ng gear of ajship ma slmllar manner I to maintain" same on her course. f

Such an application of automatic control indicated in Figure Iwherein -X- represents a; gyroscopic rotor connected electricallyormechanically by the" dotted lines to the actuating device :Y in turn connected 7 with the valve V. The action of such ade- I vice will be to automatically open-or close the valve V in consonance with the roll of the ship-which opening and. closing action g may be made controllable and adjustable as to extent 1 any s ita le wayi 1 e 1. am" aware that iniBritish patent to ialfififihof 139.8, a method of balancing an airplane having two propellers was proposed. Forbes discloses a heavier 3 than air craft fitted with two propellers driven'by a single motor through a common drive shaft and differential gear. By means of brakes applied to the individual propeller drives, either could be retarded thereby causing the other to accelerate in a like degree.

There is a distinct difference in the problemsattacked by Forbes and by my invention. A heavier than air airplane is in unstable equilibrium and only supported while in motion and is subject to complete overturning unless balancing forces are properly applied. A ship or other craft supported buoyantly, .as by floating in water, is in I stable equilibrium but is subject to periodic oscillation or roll. Forbes device is applied to the balancing of unstably supported airplanes. My invention is applied to preventing or moderating periodic oscillation or roll of buoyantly supported craft. Forbes does indeed balance the airplane by means of the forces brought about by accelerating and retarding propellers. He does. not, however, disclose what forces are thus broughtyinto use. It may be readily inferred, however, that since he illustrates propellers set at a considerable angle with the line of forward travel of the craft, he relies upon the verti-, cal component of the propeller pull in the inclined direction-which vertical component will be increased with the rate of revolution of the propeller and decreased as such rate is decreased. By accelerating a. propeller on-that side of the "airplane which is depressed and retarding that upon the side which is elevated, the lifting components of the two propellers are changed to increase that upon the depressed side and decrease that upon the elevated side.

But, however, in whatever manner it may be conceived that his invention functions, his problem was to prevent overturning of an unstable heavier than air ship in air and was not concerned with preventing or moderating a natural periodic oscillation or roll of.- a buoyantly supported craft such as a ship floating in water. 7 The present invention is distinguished therefrom not onlyin the problem to be solved but in other respects. Power is not absorbed by my method as by brake resistance. I vary the power input'to the driving engine or other motor to effect a change in torque reaction upon the ship through change in the torque transmitted without adding power losses. Forbes requirestwo propellers located upon opposite sides of the craft, preferably, at considerable distance to either side of the center line so as to increase the lifting moment of the vertical component of the propeller pull. He does not disclose balancing with'a single; propeller located on the center line or in any other position. My

v, 1,774,825 I I or more of a pluralityo'fpropellers and no reliance is; placed upon a lifting component of the driving forces developed. Although for securing automatic stabilizationl'prefer to employ mechanical means toefiect speed variations, yet my invention maybe applied to the existing craft which are already provided with means for stopping orstarting the engine or other driving motor or to vary the speed thereof by operating said means by hand without the installationof further de vices.

This application is adivision in'part of my application Serial No. 228,852, filed Octo- I Y 1 roll, into a such ship lesssub ect thereto,

her-'26, 1927.

' Other modes of applying the principleof my invention may be employed instead of the one ex lained chan es bein made a'sre ards the means and the steps herein disclosed, provided those stated by one of the following claims or their equivalent be empl0yed.

I, therefore, particularly point out and distinctly claim as my invention:-

propeller-driven water-borne ship subject to a the axis of such roll, the stepwhich consist-s in automatically varying the rate of revolu-- 1. In a method of reducing the roll ofa propeller-driven water-borne ship subject to periodic roll and having a propeller revolving upon an axis substantially parallel with the axis of such roll, the step which consistsin automatically varying the rate of revolution of the power unit drivingsuch propeller in harmonic step with such periodic roll.

2. In a method ofreducing the roll of a periodic roll and having a propeller revolving upon an axis substantially parallel with tion of the power unit driving. such propeller in harmonic. step with the initial stage of A such periodicroll. 7 a

3. In a method of reducing theroll of a propeller-driven water-borne ship subject to periodic roll and having a propeller revolving upon an axis substantially parallel with the axis of such roll,the step which consists in automatically increasing the torque delivered to such propeller when the ship'tends the ship with the rolling action thereof,

- 5. Ina method' 'of reducing the roll of a propeller-driven water-borne ship subject to p'eriodic roll andhaving at least one inde varythetorquereaction-of the propeller upon f pendently driven propeller revolving upon an axis substantiallysparallel ton-the 'axisgof roll oit' -the ship, the steps which consistin} tion of such propeller as" the ship rolls so'as to vary the torque reaction of the propeller upon the ship with the rolling action thereof,

automatically increasing the rate of revels;

and automatically decreasing the rate'of" revolution when the ship tends to. rollcounterwise'." a

6. The method of converting a propellerwhich consists in employing existing means 1 adapted to change the rate of revolution of said powerdrlveandpropeller to vary the rate of revolutionthereof in harmonic step.

with the said tendency toperiodic roll.

7. The method of converting a} propellerdriven water-borne ship subject to a tendency to periodic roll into a-such ship 'lesssubject thereto, which consists in adding to existing means adapted to change'the' rate of revolution of. a power unit driving "said propeller,'means to automatically vary the said 7 c rate ofrevolution ofsaid power unit in har- 1 driven water-borne ship subject to a tendency ,monic step withthe said tendency to periodic roll; 0

to periodic roll into 'a such ship less subject thereto, which consists in adding to existing means adapted hange the rate of revolu-' tionof a power unit driving said propeller,

said added means being adaptedto automati-. cally cause said existing means to change the rate of revolution of-the power unit and pro- '1neans to automatically vary the said rate of revolution of said power unit in harmonic p step withthe said tendency to periodic roll,

no I peller in responsetoa roll of the ship, in its initialstage. v c I r I Signed this'9th day of'June, 1928.. a v I '-I I E; RBERT II. oW.

to roll in the direction of rotation, and automatically decreasing such torque when the ship tends to roll counter to'the, directionot periodic roll and having at least one independently driven propeller revolving upon an axis substantially parallel to the axis of roll of the ship, thestep which consists in automatically varying the rate of revolution of such propeller; as the shiprolls so asto

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