US1730951A - Automatic steering for dirigible craft - Google Patents

Description

Oct. 8, 1929. E. A. sPERRY, JR 1,730,951

'AUTOIATIC STEERING FOR DIRIGIBLE CRAFT filed July 7, 1922 4 sheets-sheet l1 www-ff] I:

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Oct. 8, 1929. E. A. sPERRY, JR I UToI-TUSTEERING FOR DIRIGIBLE CRAFT Filed .my 7. 1922 4 sneefsneet 2` 3&1 zum' Oct. 8, 1929. E. A. sPERY,'JR 1,730,951

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97 ss sa al 8. 4. I l l I l l I I I I I I I I I I I I I I l I I I I I l I Patented Oct. 8, 1929 UNITED sra'rlasA APfATl-:NT OFFICE Emma a sPEnRY, Ja., or BROOKLYN, NEWYORK, assreNon., BY masNE AssIGNQ MENTS, To srEnnY GYROSCOPECOMPANY, INC., A CORPORATION OF NEW Yom:

AUTOMATIC STEERING For. DIRIGIBLE 'CRAFT l Application med July 7, 1922. serial'No. 573,280.

This invention relates to the navigation of all kinds of craft, more especiallyl to the steering of dirigible craft, such as vessels, tor` pedoes and aeroplames, which are guided by means of a` rudder. More particularly, this invention relates tonavigation of such craft by automaticmeans which operate to hold a vessel upon its course .and preventyawing movements by introducing counteracting forces upon incipient changes in heading of the craft.

This invention has for one of' its objects keeping a ship on its true course by attacking yaw in the form of an automatic device wherebV a mean helm position is not only constantly vsought and found, but re-established for every wind, tide and'current condition through which the craft is traveling. By mean helm position is meant the position of rest of the rudder which varies fromthe trueY central position due to such causes as variationin the revolutions of the propellers in multiple shown what I now consider to be a preferred screw ships, weather, direction of tides,

winds, current, etc. Any of these forces may l operate to turn the craft constantly in. one direction resulting in a small but appreclable deviation from the true or set course. To

bring the craft back to its course would necessitate swinging the rudder outwardly through a comparatively large angular'distance. As the ship reached its course, the rudder would be returned to initial position,

, but immediately the forces mentioned above would again turn the craft ofi' its course to substantially thev same extent, necessitating swinging the rudder outwardly a second time. A large yawing movement thus takes place. This vprocess would be continuous as long as the forces were present, unless the mean position of the rudder were re-set with respect to the ship to a new, or virtual, central position which would neutralize the hereinbefore mentioned forces. Having once found the mean helm, or virtual center, position, it will be apparent that a substantlal amount `of yaw has been eliminated, 'and the yaw which takes place can be much more quickly 'attacked and corrected from the new base line of the rudder. Thisv new mean position,

of the rudder allows the yaw to be corrected and incipient changes of heading to be taken care of with less'frequent shifts of the rudder, as well as less departure from the new base-line or `virtual center, thus eliminating a large amount of drag and retardation upon the forward progress of the ship.

-I-Iither-to, the setting of the mean helm position was left entirely-to the experience of the helmsman or quartermaster. Consciously or unconsciously, themore experienced helmsof this invention.

Other objects and advantages will be in part obvious and in part specifically pointed out in the speciication.-

Referring to the drawings wherein I have embodiment ot my invention,

Fig. l' is a front elevation of that portion of the steering apparatus, which is adapted to be placed in the pilot house of a vessel.l

Fig. 2 is a plan view of a master course controller shown in Fig. I.

Fig. 3 is a verticalsection through thev master course controller.

Fig. 4 is awiring diagram of the course control mechanism. I

Fig. 5 is a plan view of the automatic helm positioning means.

Fig. 6 1s a vertical section through the device shown in Fig. 5.

Fig. 7 is a front diagrammatic view-of the contact-'controlling means forming part of the device in Fig. 5.

Fig. 8 is a plan view of aeportion of the device of Fig. 5, showing the parts indifferent operative relation to set the rudder for helln.

Fig. 9 is aplurality of graphs or records illustrating the principles of navigation em bodied in this invention.

Referring to F ig's. 1 to 3', I locate, preferably .in the pilot-house of theship, a master controller. 1 from whichthe rudder is automatically controlled. The system of coursecontrol by the mechanism of F igs.. 1 to 4 inclusive is fully set forth and claimed in the copending application of Chester B. Mills, Serial No. 569,295, Automatic steering for dirigible craft, and for a more complete description, reference should be had thereto,

but it will be described here briefly. Said master controller is shown mounted on a stand 3 and performs the functions both of a steering repeater compass and a master controller, the standard repeater compass card 10 cooperating with the settable course indicator 11. The indicator, or pointer 11, is mounted upon a shaft 12 concentric with card 10, controlled from a repeater motor 13. The entire mechanism is enclosed in a casing 9 having the usual glass cover 14 and bezel 15. The card is rotated by the motor 13 through gears 16, 17 to rotate shaft 18 and gear 19 thereon, gear 19 mashing with ,gear 20 on a bushing 21 jounralled in a. partition plate 22, said card being fixed to the upper end of said bushing.

To set the pointer relative to the repeater card the usual handle 30 may be provided which operates by means of bevel gear 31 a differential comprising upper gear 32 and lower gears 33, 34, the gears 31 and 34 mesh-` ing with gears 35 and 36 of a planetary member 37 fixed to shaft 18. Since shaft. 18 is rotated by the repeater motor, operation of handle 30 will rotate gears 35 and 36 about their axes to rotate gear 32 and gear 40 fixed thereto, said gear 40 meshing with gear 41 fixed to the pointer shaft 12. Fixed to gear 32 is a trolley 50 meshing with contact strips 51,

{i2-arranged in the formy of rings, here shown l positioned to one side of the casing. It will be obvious that when a new course is set by handle 30, or when the ship turns off its course, so that trolley 5() is rotated by the repeatermotor along the contact strips 51, or 52, there is set in oper-ation the following means to move the ship to a new course or bring it back.- after it has moved offy its course. Y A' Any devitation of the ship from its course will cause rotation of gear 32, and hence, of the card 10 and the trolley 50. Referringl to Fig. 4, it will be .observed that the trolley 50 is in the form of a lever which carries three contacts 68, 69 andV 70, the first two upon one arm thereof and Athe` last upon the other arm. Contacts 68`and 7 0 engage contact strips 51, 52, 71, 72, 73 and` 74 of a contact ring, while Contact 69 engages a separate contact 7 6. The operation of the device is as follows: L

' Oase 1.-Assume slight yawing movement in a clockwise direction insuflicient to move contact 68 olf insulation 54 between contact strips 51 and 52. Acircuit is then established from main lead'140, contacts 69 and 7 6, to an auxiliary control `device 25. Said device comprises brushes 26, 27, 28 and 29, controlled from a repeater motor 39 similar to motor 13, and cooperating with a contactor ring or commutator 38. Said commutator has live segments 43 and 44, the former cooperating with brushes 26 and 27, and the latter cooperatino' with brushes 28 and 29. All of said brushes normally contact with insulated strips 45.

So that in the'case here discussed, brushv 28 engages contact 44, and the circuit continues through said contacts 80, 81, and relay coil 82, closing a circuit through coil 83 of a motor 84 to drive the rudder in clockwise direction and move the ship counterclockwise to counteract the yaw. The end of the rudder 46 is provided with a block 85 which closes a set of contacts 86, when said rudder moves as desired, to break the circuit through field coil 83 by 'energizing relay 80. The rudder is held in this position until the ship turns back counterclockwise sufliciently to move brush 29 into engagement with contact 44 to establish a circuit through relay cone. tacts 87, 88 and relay coil 89 which closes a circuit through oppositely-wound coil 90 of motor 84 to drive the rudder counterclockwise and turn the ship clockwise. When the rudder engages contacts 91, it breaks the circuit through coil 90 by energizin relay 87. These small oscillations of the ru der between contacts 86 and 91 are thus continued during the small yawing movements of the ship to counteract such movements. The relays 82 and '89 are normally open, and when closed, serve to close the circuit through the motor from main lead 140 to main lead 141. f

Oase Z-Assume greater deviations of the ship so that contact 68 engages contact 51 oi 52, contact 70 does not move out of engagement with contact 74, and contact 69 does not move out of engagement with Contact 76. If

the ship yaws clockwise, a circuit is established from main lead 140, contacts 68, 51,43, 26, relays 81 and 82 to coil 83 of the motor, and another circuit from contacts 69, 76, 44,

28, relays 80, 81, 82, also to coil 83 tol drive the rudder clockwise and turn the ship counterclockwise to counteract the yaw. When the i rudder closes contacts 92, it forms a circuit including contacts 70 and 74 to break the circuit through coil 83 by energizing relay 81.

Trolley 5() rotates through the full angle of deviation, but the commutator of the auxiliary control device 25 is limited to a very small movement by stops (not shown) and a slipfriction connection between the commutator and its shaft, which permits the shaft to con-l tinue to rotate after the commutator has been stopped.

l Because of the smallmovement of the coinmutator, as soon as the ship starts to turn clockwise, brush 26 moves olf contact 43 while p contact 68 is still on contact 51, and brush 28 I agesmovesoff `contact 44. Brush 29 now en contact 44 to establish a circuit throug the i tion, the lower set of relays is lower relays andi-coil 90 to drive the rudder until the rudder'engages contacts 93. AAs

-soonas the ship starts to turn back, the up er `set of relays is energized to return the rud er,

until the latter engages contacts 86 to energize relay 80. f

Uase 3.-Assume in case 2 that the deviations are suiiicient to move contact 70 into en -l -gagement with contact 72 or 73. The operation would be the saine as in' case 2. except y that the'circuits'which control the limiting as it nears-its Y tions '3, to swing' I ,the momentum of the positions of the rudderwould now be from contact 70, contact 72 or 73, to contacts 94or 95 instead o 92 and 93, greater swinging ofthe rudder corresponding to the gieaterangle of deviation of the ship.

Gase gif-'Assume that handle 30 is operated to movie trolley -50, vor that the ship yaws to an unusual extent,

moves beyond contact 76 and that contact 7 0 vmoves beyond contact 72 or 73. Contact 68 still engages co tact 5 1 or '52. Assumethat counterclockwise movement of Y the ship .is necessary to bring it to its new course. A circuit is established which includes lcontacts 68 and 51, rela i s 81 and 82to coil 83'to drive the rudder cloc Wise and turn thev ship counterclockwise. .When the rudder' reaches limit.- in contacts 96, it breaks the 'circuit through coil 83 by energizing relay 81. -As the ship starts to turn counterclockwise, however, no

circuit is established through coil 90 to return 41j `the rudder, as in preceding-cases, since contact 69 is oif contact 76. The .rudder therefore, holds its 'extreme'positiom causing the ship to turn rapidly and continuously, until,

course,

tact 7 6, and thereafter the device operates as in the other cases-j The rudder is returned 'before the ship reaches its. course, allowing the momentumof the ship to bringit to its course.`-

When-the .ship is toebe turned -clockwise, the lowerset' of relays venergizes coil 9() to drive the rudder counterclockwise, until it engages stop 97 to energize relay 88 and break the circuit. -When contact 69 engages contact 76, the upperset of relays is'effective to energize coil 83 Yand return the rudder. It is thus apparent that for small deviathe device operates as in cases the rudder outwardly a distance proportional to the deviation, and as soon as the Ship startsback, the rudder is returned, shipbeing suicient to carryr it to its course.- For large' deviations, however, the rudder is held in extreme position, until the ship approaches Aits course.

or yawin alarm may and thus permit a y .such that contact 69,-

'meclianism is contact 69 engages con-- tervaL Thereafter,

1', 2 andVV Before the shipreaches its course, the rudder is returned and the momentum thus imparted is suiiicient to bring the ship to its course.

It Will also be apparent that it-is imniaterial how trolley comes-into engagement with the contact strips, whether through yaw- 'l .of energy 99 may be provided in circuit with trolley 50 and contacts 71, so that an alarm is sounded whenever such unusual turning.

of the ship takes place, cause trol ey 50 to engage said contacts. The

thus serve to warn against unusual atmospheric orv tidal conditions or faults arising from the ship proper.

The motor 84 maybe arranged to control a steering mechanism, such as a telemotor of the usual type. Thus tlie`motor shat 110 may operate va' pinion 111 which engages two as will l racks 112 and 113 on opposite sides thereof.

vSaid racksoperate 'as plungers in cylinders 114, 115, so that rotation of pinion 111 Will cause one plunger to move inwardly in its cylinder and the' other plunger to move outuardly. This causes a displacement of the 'fluid to one side which is transmitted byV pipes 116, 117 connected to cylinders 114, 115, respectively, to the opposite sides of the steering engine 120, 121, whichis geared tothe sector l22,integral with the rudder. Further details of the steering' engine are not essential vfor the purposes of disclosing vthe present invention, since such enginesa're standard commercial units and -well known in the art.

It will be observed that it is the rudder ,that controls the course control mechanism by a follow-'up mechanism. This follow-up therefore independent of the steering engine used to operate the rudder, and hence all errors arisingin the telemotor. its gearing transmission, etc. Vare eliminated so far as the course control mechanism is concerned.

Motor 65 is a' series\ motor, one of the characteristics o f which is the picking up'in speed the longer it runs,'witliin afgiven inas the counter E. M. F. builds up, the speed diminishes. This action .of the motor isdesirable because for small movements of' the rudder only the initial, comparatively slow speed of the motor is utilized, but Where the rudder is to be operatedthrough greater distances, the motor picks up speed the longer it rotates and thus drives the rudder more rapidly than for small angular distances.; It may occur, however,

that the rudder isopera-ted through so great an angular distance that the motor rotates long enough for the second phase, i. e., the diminishing speed, to set in. To prevent such diminution in speed, there may be provided a relay 125, the coil 126 vof which is in series e with a resistance 127 the inotoincircuit.

When the counter E. M. F. builds up, relay 125 is operated to short circuit resistance-127 and thus increase the speed of the motor. .The system may be made sensitive by employing a plurality of relays similar to 125 adapted to be operated successively to cutout an increasing amount of resistance and thus If a vessel yaws equally from .side to side,

the rudder will be operated through equal angular distances to either side of the true course, in orderlto counteract these. yawing movements. Due, however, to such forces as the direction of the wind, the variation in the revolutions of the propellers in multiple screw ships, the tides and currents, the vessel is often continually forced off` its course in one direction. The rudder instead of being operated equally to either side of the true course must now be operated through a segmental portion whose central axis Iis considerably to one side ofthe true course, thus causing the ship to follow a new course which 'slightly deviates from the true course. This variation of the mean position of the rudder from the true mean position (i. e.,`th e true course of the ship) is termed the helm- In the present invention as hereinbefore describe-d, to counteract these additional forces, the rudder would be thrown outwardly an angular distance sufficient to bring the ship back to its course. 'Ihe rudder would be returned shortly before the ship reached its course, withthe result that the ship would again be turned.I olf its course by these extraneous forces, necessitating operation of the rudder in the same direction again. There thus results a continuous yawing movement of the ship mostly to one side of the true course, and to avoid repeating this process as long as the extraneous forecsare operative, means are provided for preventing this lyaw by Y changing they relationship which exists between the compass and the rudder and automatically determining the helm, i. e., .estab-v lishing a' virtual center which 1s such a position of rest of the rudder varying from the true center position, as will be sufficient to counteract ,the effects of the extraneous forces and keep the ship on its true course. In other words, where heretofore the indications of the ships course on the compass corresponded to the true central position of the rudder, the same indications will correspond to the mean position of helm.

through link lrelative to segment'155.

For automatically determining the mean position of helm, the rudder 46 (see Figs. 5 to 8) is connected by means of an adjustable link to a segment 151 mounted upon a vertical shaft 152 journaled in a boss 153, forming part ofa base 154. Fixed upon said shaft between segment 151 and boss 153 is a second and larger segment 155. The latter ca'rries operating links 156, 157 extending therethrough, and preferably having rollers 158 at their lower ends, which are normally pressed into engagement with base 154 by springs 149. Said operating links are adapted to cooperate with cams 16() and 161 positioned on said base, said links andeams being so' positionedthat equal angular movements of segment 155 to either side of center line Y-Y will causeoperating link 156ito engage cam 16() or operating link 157 to'engage cam 161 to force the respective'link upwardly and operate a ratchet 165 or an oppositely toothed ratchet 166, respectively. Said ratehets are fixed to the ends of a shaft 168 journaled upon segment 155 and having akwor'm 170 formed thereon meshing with a rack 171 on the peri phery of segment 151. It will thus be seen that rudder 46y is movable integrally with segment y155, as well as relatively thereto, 150, worm 170 and gear 171 and any movement of the rudder will` cause corresponding movement of segment 155. Assuming that there are no extraneous forces,

the rudder 46 moves equal angular distances to either side of line X-X to counteract yawing movements of the ship. Segment 155 therefore also moves equal angular distances to either side of line Y-Y. If these distances are very small, links 156, 157 will not reach cams 159, 160, but if the distances are comparatively large, each operating link will engage its respective cam. Operating link 156 will engage cam and be raisedV against the action of spring 149 to cause a pawl member 175 carried at the upper end of the link to engage ratchet which is thus operated to rotate worm and so move rudder 46 relative to segment 155. As the rudder moves to the opposite sidel of line X-'-X, link 157 engages cam 161 to cause a pawl 180 carried hy said link to operate ratewt 166 in the reverse direction to ratchet 165 and so restore the original relative positions ofthe rudder -and segment 155. Springs 177 may be provided to engage the pawls, and move them out of engagement with the ,ratchets when the operating links are lowered.

Assume, now, that extraneous yforces arev acting upon the ship, necessitating in'vement of the rudder toward the right, counter-clockwise, to bring the ship back to its course. In so moving the rudder to the right, link 156 engages cam 160 to operate ratche166- and move segment 151 and rudder 46 to the right its course, the rudder is returned until seg--` When the ship nears of the ru ation of the'rudder to act the uextraneous ment 155 is on its center line Y-Y, but the rudder is now positioned slightly to the right of X-X. Instead of swinging to the left of line Y-Y, as in ordinary yawing, the extraneous forces again move the ship off its course, before link 157 has engaged cam 161 to operate ratchet 165, necessitating operation of the rudder to the right to operate ratchet 166 again. The continued operation of the ratchet 166 moves the rudder continuously to the right of center line X--X and relative to segment 155, thus giving the rudder a permanent set or helm ofi' .its 'true center suficient to counteract the effect of the eX- traneous forces. The ship is thusheld upon its course except for those yawing movements which give rise to equal -angular movements dder to either side of its mean position of helm indicated by line' Z-Z in Fig. 8, causing equal operation` of ratchets 165 and 166 -to maintain therelative positions of the rudder and segment 155. The lineZ-Z is the new or virtual center position of the rudder and there is thus avoided the necessity of re )eatedly swinging the rudder from line X to line Z-Z, to counterforces which necessitate the settingofhelm. Large yawing movements of the craft are therefore prevented by this automatic helm positioningdevice.

If extraneous forces should now operate on the ship, to turn it off its course in a direction so as to necessitate repeated operthe left, clockwise, ratchet 165 will be operated' more frequently than ratchet 166 to move the rudder to the left relative to segment 155. Thus, any extraneous force which would tend to throw the ship steadily off its course is automatically compensated by the positioning of helm effected by the unequal operation of - ratchets 165 and 166, to counteract such force, so that steering of the ship may progress as if such force were not present. The mean position of helm -is thus the base linefrom which the steering mechanism operates. The device is thus constantly setting itself to the scientifically accurate virtual center or mean posivariations.

tion of helm for maintaining the true course. A v

The adjustable link 150 comprises two portions connected by a turn-buckle 190 whichv ermits the initial relative positions of the rudder and the segment 155 to be adjusted to take care of such variations as are due to the particular vessel, or any other' known By referring tothe graphs of Fig. 9, the principles of navigation embodied in this in-` l,vention may be illustrated. In all of these graphs the rudder movements are recorded. Referring to graph 1, it will be seen that theY rudder was operated for small angular distances (shown here as'about 2) which would correspond to movements between contacts 86 steadily to the right.

' (shown here as ap der, are here mounte ,way

lof the rudder varies and 91, or sufficient to counteract ordinary yaw. The aph shows an occasional rudder movement eyond these points, but on the `whole the yaw takes place eq;i lly to either sidev of the actual center X- The condition where an extraneous force sets in to turnthe craft constantly o' its course is illustrated in graphs 2 a force is acting to turn the craft constantly toward the right. Graph 2 is a record of the rudder movements which are due `to an inexperienced helmsman, or to automatic steering means which makes no provision for automatic determination of helm. Between the points A and B the vessel yawed nornally. Thereafter, forces tended to turn it off its course constantly toward the right. The helmsman or automatic steering mechanism hereinbefore mentioned threw the rudder outwardl (to a point here shownas 8) and broug t the craft back to its course, Whereupon the rudder was returned to center position X-X, but no sooner did the craft reach and 3, where its course, than it was turned off toward the right again, necessitating operating the rudder outwardly again, through 8 in the same direction. This operation was continued as long as the said force acted to turn the ship 3, there is illustrated the manner in which an automatic steering mechanism equipped with the automatic mean helm determining mechanism of this invention met the situation or condition present in graph 2. The portion A--B corresponds to the portion A--B of graph 2,. lThe portion B-C, however, illustrates the operation of giving the craft helm. Instead'of returning the rudder (which has been swung outwardly the same 8 as in (graph 2) to center line X-X, it is stopped short of said line by constantly increasing angular distances intil a new center line position wasA found. In the graph this line is shown as 6 to the right of thev actual center X--X, indicating that lby offsetting the rudder 6, thet force which tends to turn the craft steadily off its course is neutralized. Thereafter, ordinary to and fro movements of therudder roximately 2) takes lace to either side of t e virtual center Z- instead of the large rudder movements (about 8) in graph 2 under the same conditions. This of course also means that the am litude of the yaw is correspondingly reduced.'

The follow-back contacts, which in the diagrammatic representation of Fig. 4 are shown as engaged directly. b the bar on the rudon base 154 and so positioned as to be engaged bythe bars 178 and 179 on the segment 155, since the latter alsmaintains the same initial position relative Referring to graph according to the mean position of helm. Said bars 178, 179 are l to said contacts, while the initialposition l spaced in planesone above the other. The contacts 91, 93, 95 and 97 are arranged in the path of bar 178, while contacts 86, 92, 94 and 96 are arranged in the path of bar 179. L In accordance with the provisions of the patent statutes, I have' herein described the principal of operation of my invention, together wlth the apparatus, which I now consider to represent the best embodiment thereof, but I desire to have it understood'that the apparatus shown is only illustrative and that the invention can be carried out by other.

combination with the compass governed con-l troller and rudder, of means responsive to' persistent yawing movements ot the ship in one direction from the course, and means operated thereby for changing the relation between the compass controller and rudder to centralize the oscillations of the controller and rudder. i, v

2. In combination with a steering mechanism of a dirigible craft 4including a rudder, a control member actuated in accordance with movements of said craft on opposite sides of its course, adjustable means connected between said rudder and said member whereby the relation of said rudder with respect to said member and said craft may be varied, and means for automatically actuating said adjustable means upon persistent movements of said member to one side of its cent-ral position to change the normal relationship between the rudder and control member for the purpose specified.

3. In combination with the steering mechanism of dirigible craft, means for counteracting movements of the craft to either'side of its course and means operated by the unequal `movements of the craft on opposite Sides of its-course for automatically altering the mean position of the rudder to equalize said movements.

lll The combination with the automatic steering mechanism for dirigible craft including a compass and automatic means governed thereby forv actuating the rudder, of means for altering the relationship between the compass and rudder, and automatic means brought into action by successive unequal movements of steering mechanism to one'side of the neutral position for operating said first-named means.

5. The combination with automatic steering mechanism for dirigible craft having a ments of the craft on opposite sides of itsv course for operating said member, an intermediate adjustable member connectmg said first-named member and rudder, and means actuated by unequal excursions of said member for operating said adjustable memberto change the relation between the rudder and controller for the purpose specified.

G. The combination with automatic steering mechanism for dirigiblc craft having a compass governed controller and a rudder,

of means for preventing deviation from the' course by side winds and the lilre, said means comprising a member mo.'ably connected to said lcraft, adjustable nieans connecting said member and rudder, and means'actuated in accordance with unequal movements of the craft on opposite sides of its course for operating said adjustable means to change the normally fixed relationship between the rudder and controller. l

7. 'The combination with automatic steer'- ing niechanism for'dirigible craft having a rudd .-r, o'f means for automatically determining the mean. position of helm, said means comprising a member movably connected to said rudder and craft, and means whereby unequal movements of said member on opposite sides of its central position operates said member and rudder to set a new'base line for said rudder.

8. The combination with automatic steering mechanism for dirigible craft having a` rudder, Aof means for reducing the rudder movements, said means comprising a member movably connected to said rudder and craft and means whereby unequal movements lot' said member on opposite sides of its base line operates said `member-and rudder to set a new base line for said rudder.

9. The combination with automatic steering mechanism for dirigible craft having a rudder, of means for automatically determining the mean positionof helm, said means comprising a member movably connected to said rudder and craft and means whereby unequal movements of said member on opvpositeI sides of its base line operates said member and rudder to set anew base line for said rudder, the deviatlon of said new base lin'e from the old base line being m proportion to the degree of inequality of said rudder f movements. f

10. In automatic steering mechanism for dirigible craft having a rudder, the combination with a' master controller of means for altering the relation between the rudder and controller to alter the neutral position of the former, said means comprising mechanism whereby unequal movements of said rudder on opposite sides of its neutral position moves the rudder with respect to said controller in a direction of said greater rudder .movements from said position.

11. In automatic steering mechanism for dirigible-craft having a rudder, the combination with a master controller of means for altering tlierelation between the rudder and controller to alter the neutral position of the former, said means comprising mechanism whereby unequal movements of said rudder on opposite sides of its neutral position moves the rudder with respect to said controller in a direction of said greater rudder movements from said neutral position.

12. The combination with automatic steering mechanism for dirigible craft having a rudder, of means for reducing the rudder movements, said means comprising means for offsetting the neutral position of said rudder with respect to said 'automatic steering mechanism when the` rudder is continuously operated more to one side of its normal neutral position than to the other and means for offsetting the neutral position in the 0pposite direction when the rudder is continuously operated more to said other side of its said normal neutral position than to the 'first side, for the purpose specified 13. The, combination with automatic steering mechanism for dirigible craft having a rudder, of means for automatically determining the mean position of helm, said means comprising a member connected to said rudder, a second member adjustably connected to said first-member, and means for operating said irst member relative to said second'member, when the rudder operates to one side or the other of its base line, to move said first member and rudder in a corresponding direction relative to said second member and Oifset the base line in said direction.

14. The combination witlr automatic steering mechanism for dirigible craft having a rudder, of means for automatically determiningv the mean position of helm, said means comprising a member connected to said rudder, a sec-ond member adjustably connected to said first member, and means for operating said first member relative to said second member, when the rudder operates to one side or the other of its base line, to move said first member and rudder relative to said' second member to offset the base line.

15. The combination with automatic steer.

ing mechanism for dirigible craft having a ',rudder, of means for automatically 4ing` the mean position of helm, said means comprising a member connected to said member adjustably connectdeterminrudder, a second ed tov said first member, a plurality of mechanisms vfor movingsaid first, member and rudder relative to said means for operating one of said mechanisms to oset'the base luie of the rudder 1n one second member anddirection when said rudder is operated to one side of said base line and for operating the other of said mechanisms to offset the base line in the other direction when said rudder is operated to the other side of said base line.

1.6. The combination with automatic steeringmechanism'for dirigible craft having a rudder, of a member connected to said rudder, a second member adjustably connected to said first member, means for varying the relation between said two members, including a plurality of mechanisms for moving said rst member4 and rudder relative'to said second member, one of said mechanisms operating said means to' oset the base line of the rudder in one direction and the other of said mechanisms operating said means to offset the base line in the other direction and means for 'operating one of said mechanisms when said rud der is operated to one side of said base line and for operating the other of said mecha-- nisms when said rudder is operated to the other side of said base line.

17. The combination with automatic steering mechanism for dirigible craft having al rudder, of a member connected to said rudder` a second member adjustably connected to said first member, gearing between said members, a pluralityof mechanisms for operating said gearing to move said-first member .and rudder relative to said second member, one of said mechanisms operating said gearing to offset the' base line of the rudder in one direction and the other of said mechanisms operating said gearing to offset the base line in the other direction, said mechanisms each' comprising'a pawl and ratchet and an oper- 4 ating member carried by said seoondmember for operating said pawl and ratchet and means for operating one of said mechanisms when the rudder is operated to one side of the base line and for operating the other of said mechanisms when the rudder is operated to the other side of said base line.

18. The combination with automatic steering mechanism for dirigible craft having a rudder, of' means for automatically determining the mean position of helm, said means comprising a member connected to said rudder, asecpnd member adjustably connected to said first member, gearing between said members, a plurality. of mechanisms for operating sald gearing to move said member and rudder relative to said second member, one of said mechanisms operating said gearing to oset the base line of the rudder in one direction and the .other o fsaid mechanisms operating said gearing to oset the base line inthe other direction, said i'nechanisins` Jeach,comprising; a pawl and ratchet and an operating member carried by said second memberfor operating said pawl and ratchet and a plurality of cams, eachpof said operating members being adapted tov engage one ofl said cams to be operated thereby when said rudder is operated to one side or the other of the base line. i v

19. 'The combination withv automatic steering mechanism for-diiigible craft having a rudder, a membei' m'ovably connected to said rudder and craft, and means actua-ted in accordance with the movements of the craft on opposite sides of its course for operating said member and settingsaid rudder, said member being adjustably connected to said rudder to vai'y the position of the rudder.

- relative tothe steering mechanism.

erned -thereby for actuating `the rudder, of:

20. In an automatic steering mechanism for dirigible craft having a rudder and course indicating means. means for setting said rudder in predetermined relation to said indicating means, and means controlled by the movements of the rudder for automatically changi'ng thel relationship between said indicating means and said rudder.

21A. In an automatic steering Imechanism for dirigible craft having a rudder land course indicating means, said rudder being normally set in predetermined relationto -said means, `means-'whereby said rudder is operated to counteractmovements of the craft off its course,'and means for -,automatically changing the relationship between said l a follow-back systembetween the rudder and said means, and means for altering the position of the rudder with respect to said foliow-baclcsystem to change the relation between tliecompass and the rudder.

24. In an automaticy steering device, a means 'for preventing deviation of a ship from'itscourse comprising means responsive to yawing of the ship to oneside of the course, and means operated by said second named means forcorrecting the relative positions of the controller and rudder to maintain the ship on its original course.

Q5. In an automatic steeringdevice for ships, a mea-ns for preventing the deviation 'of a ship from its course, comprising the conibination with the compass and rudder, ofurieans responsive to yawi'ng of".the ship to one side of its course, thereto for 'changing the relation between the compass and rudder to maintain the ship on its original course.

and means responsive 26. In an automatic steering device, a means for preventing deviation of a ship from its course, comprising means responsive to yawing of the ship to one side of the course, and automatic means operated by said second named means for correcting the setsignature.

ELMER A. SPERRY, JR.

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