US2374892A

US2374892A - Radio antenna controlling system

Info

Publication number: US2374892A
Application number: US463981A
Authority: US
Inventors: Edward S Peterson
Original assignee: Automatic Electric Laboratories Inc
Current assignee: Automatic Electric Laboratories Inc
Priority date: 1942-10-30
Filing date: 1942-10-30
Publication date: 1945-05-01
Anticipated expiration: 1962-05-01

Description

May 1, 1945.

E. S. PETERSON RADIO ANTENNA CONTROLLING SYSTEMS Filed Oct. 30, 1942 FIG.2

BELLY LINE OF THE AIRCRAFTW SOURCE OF DIRECT CURRENT 4 Sheets-Sheet l INVENTOR. EDW RD S. PETERSON BY v Z TQBM May 1, 1945. E. s. PETERSON .V| RN E 00 N TS R m m 2 VW a mE A e P h J cw S. m e

A, M N W... 4 m D T E m w N m m I s2 6 Y MM H 8 I1 m O0 7 R3 T G s N 2 0+- I w F Ma m ml Ti L .M W O I m R y 1 1945- E. s. PETERSON ,3

RADIO ANTENNA CONTROLLING SYSTEMS Filed Oct. 30, 1942 4 Sheets-Sheet 3 INVENTOR. EDWARD S. PETERSON ATTORNEY y 1945. E. s. PETERSON RADIO ANTENNA CONTROLLING SYSTEMS Filed Oct. 30, 1942 4 Sheets-Sheet 4 Rm mm Wm mP S. WU M D 5% m m w L $323 09 o: E Q: m: 3. f v NQ mm a r q 3% gi 02 ZT 50 ATTORNEY Patented May 1, 1945 RADIO ANTENNA CONTROLLING SYSTEM Edward S. Peterson, Elmwood Park, 111., assignor to Automatic Electric Laboratories, Inc., a corporation of Delaware Application October 30, 1942, SerialNo. 463,981

8 Qlairns;

.Tliis invention relates in general to radio antenna controlling systems, and more particularly to novel arrangements for controlling and indicating the operation of aircraft antenna reels.

It is well known to employ a trailing wire antcnna in aircraft and to provide, within the body of the craft, a reel or bobbin upon which the antenna is wound when it is not in use. Further, it is well known to unwind different amounts of the antenna at different times whereby to vary the length of antenna trailing the aircraft; since each frequency (or wavelength) of transmission has its own optimum antenna length, it will at once be apparent that this control over the length of the extended antenna affords a ready means for securing optimum performance of the antenna on whatever transmission frequency (or wavelength) is to be utilized in any given instance.

While an antenna reel may be provided with extend or retract the antenna, it is, for obvious reasons, highly desirable that he be relieved of this task and that the operation be made semiautomatic. Moreover, the advent of larger aircraft with increasingly complex controls frequently makes it desirable to place the reel at a considerable distance from the operator, in a part of the aircraft which is less congested than that in the immediate vicinity of the operator.

The primary object of the invention, therefore, is to provide a semi-automatic antenna reeling system wherein the reel itself is remote from the operator and wherein, for the sake of utmost flexibility of control, the operator is able to adjust the length of the trailing antenna with the same certainty and freedom as though he had a direct manual control over the reel. With this end in view, I have provided a semi-automatic, remotely controlled antenna reeling system wherein the reelis operation is at all times subject to the oper ators will. giving him the power to start, stop or reverse its rotation whenever he desires, .and wherein :the operator is instantly apprised of every change made by the reel in the length of antenna extended. A feature of the invention is the provision of a rotatable antenna reel having means for at all times indicating at a remote point the number of x trical conductors interconnecting the two. Other features include the provision of means under control of the reel for causing said remote motor to operate in diiierent directions at diiierent times, the direction at each time depending upon the direction of the reels rotation; the provision of means under control of the reel for starting and stopping said motor, as the reel itself starts and stops; and the provision of means under control of the reel mechanism for automatically disconnecting said remote motor from its source of current each time the antenna is completely retracted and thereafter reconnecting it just prior to a subsequent extension of the antenna, so that said motor will not be an undue drain on the aircrafts power su ply during the long periods wh en the antenna is'retracted.

A further feature is the provision of means for operating a remote electric motor by electrical impulses transmitted thereto under control of the antenna reel mechanism. Another feature is the transmission of said impulses over a plurality of circuits in a sequence depending upon the direction of rotation of the reel, the remote motor operating in a direction depending upon the sequence of said impulse transmission.

(Still another feature is the provision of an 'antenna reel mechanism and a remote indicator lay whose delayed operation bridges the period of the transient condition and absorbs its effect.

Further features and objects of the invention will be apparent from the following description of one embodiment thereof, reference being made to the accompanying drawings, in which Fig. 1 is a front elevation of'the control unit for the reel, showing the cable connected thereto,

Fig. 2 is a side elevation of the control unit with the cable disconnected,

Fig. 3 is a perspective viewof the box.which covers the rear of the control unit.

Fig. 4 is a front elevation of the reel and its driving unit, showing the cables connected thereto, v

Fig. 5 is a top elevation of the reel and its driving unit,

Fig. 6 is an end elevation of the reel and its driving unit, as seen when viewed from the left side of Figs. 4 and 5, the cables'having been detached from said driving unit,

Fig. 7 is an enlarged back view of the control unit illustrated in the Figs. 1, 2 and 3,. with the back cover removed to show the mechanism contained therein,

Fig. 8 is a sectional view taken along the line 8-8 of Fig. '7,

Fig, 9 is a sectional view taken along the line 9-9 of Fig. '7, certain parts having been omitted for the sake of clarity,

Fig. 10 is aside elevation of the control unit, as 'seen when viewed from the right-hand side of Fig. 7, certain parts having been omitted in the interest of clarity,

Fig. 11 is an enlarged top view of the driving unit for the reel, with the top cover removed and with part of the motor casing cut away to show, in cross section, the clutch mechanism,

Fig. 12 is a front view of the driving unit, without its motor and with the front cover-removed to show the contactor and limit'springs.

Fig. 13 is a sectional view taken along the line I3|3 of Fig. 11, the motor being omitted,

Fig. 14 is a perspective view. of the contactor.

Fig. 15 is an enlarged longitudinal section of the worm and limit disc assembly illustrated in. I

Figs. 11 and 13, and

Fig. 16 is a schematic diagram of the apparatus illustrated in the above figures together with the electrical circuits comprising the control system therefor.

The apparatus disclosed in the drawings is divided into two electrically interconnected units, and before explaining their interdependent operation as components of a single system, the

mechanism of each unit will be described sep arately. I

The control unit (Figs. 1, 2, 3, 7, s, 9 and 10) The control unit is housed within agenerally rectangular box 2|] having cover 2|, and should be positioned in the aircraft within the sight and reach of the pilot or radio operator. It may be mounted upon any suitable support by means of the screws 22 which pass through the holes in the back of the box, the cover thereafter being across the bottom of the box to permit a receptacle or jack 26 to be mounted therein. When the cover is in place, the upper part of this receptacle fits into a wide slot 29 provided in the bottom wall of box 20. All electrical connections to the control unit are made over a ten conductor cable 21 having a plug 28 which is insertable into said receptacle or jack.

Mounted on the inside face of the cover by means of two L-shaped' brackets 30 and 3|, is a three-gang motor of the type disclosed in my copending application Serial No. 450,102, filed July 8, 1942. This motor has three generally U-shaped

stator pole pieces

32, 33, and 34 spaced apart one above another. They are supported thus by a pair of

vertical rods

35 and 36 passing through holes in the brackets 30 and 3 I, through corresponding holes in the free ends of each pole piece and through spacing sleeves such as 37. Nuts at both ends of each rod securely clamp the stator pole pieces between said brackets, forming a rigid field structure. The pole pieces are of softiron or other magnetic material, and each has a magnetizing

coil

38, 39, 4B) wound around its center section.

Parallel to the

rods

35, 36 and centrally disposed between the ends of the pole pieces is a rotatable shaft 4| supported at both ends by selfaligning bearings such as 42. The top bearing is seated in a concave socket stamped in the bracket 30, and is held there by a resilient retaining plate 43, similarly stamped, which is secured to the

rods

35, 36 by nuts. The'lower bearing is held in like manner between the bracket 3| and a re silient retaining plate 44.

Three

rotor elements

45, 46, and are rigidly fastened to the shaft 4|, each lying in the space between the open ends of one of the pole pieces. Like the pole pieces, these rotor elements are of soft iron or other suitable magnetic material, and as best seen in Fig. 16 they are staggered at angles of from each other.

Linked to the shaft 4| by means of a worm 48 and a gear 49 is a counter 50 of the Veeder type.

'This is secured by screws to the inside of the cover of the control box, its registration being visible from outside the box through a window 5|. The ratio of the worm-to-gear linkage just mentioned preferably is such that the counter will read directly in terms of revolutions of the shaft 4|; in other words the total registration visible through window 5| should increase one unit for each revolution of the motor shaft in one direction and should decrease one unit for pressing the reset knob against the force of spring 54 the outer edge of disc '55 will be brought into engagement with the periphery of the rubber disc, and if the knob then is rotated while thus depressed the disc 55 will rotate the shaft '4! through its frictional engagement with the rubber disc, causing the counter reading to be changed accordingly.

A tell-tale lamp assembly 5'? of well-*known type is mounted in the lower corner of the cover. This has a miniature incandescent lamp '58 suitably supported in a socket 58 and is clearly visible from the front of control box when lighted. Also mounted on the inside of the cover is a three position rotary switch 60, which may, for

When the switch is displaced either to its in position or to its out position ,a sprin member, 53, fastened to the swtich shaft, will maintain it in that position until it is manuall restored to its normal, or on, position.

On an L-shaped bracket 63 which is attached by screws to the inside of the cover there is mounted a horizontal relay of the telephone type. This relay has a core 64, an Leshaped heel piece 65, .andan L-shaped armature 66., all of magnetic material. the heel piece and the armature is pivoted on a knife edge 61 at the other end of the heel piece. Around the free end of the core .is wound ,a coil 58 which when energized attracts the armature '65, thereby opening an electrical contact 69 mount- .ed on the heel piece. A heavy copper collar, or slug, 1D is mounted on the core adjacent to the winding '58 which, as is well known, makesthe relay .slow-to-zrelease '(i. -e., delays the restoration of the armature to normal upon deenergization of the winding) Since the entire mechanism of the control unit is mounted on the cover .2! as explained above it may easily be removed for inspection, adj-lash mcnt, or repair simply by removing the screws .23 which-hold the cover in place, and it may be disconnected from the driving unit simply by removing the plug 28 from the jack 26.

The dTiving (F'igS. 4, 5, 6, 11, 12, 13, 14 and 15) The antenna reel H is rotatably mounted ona spindle to the channel-shaped member 12. The latter member may be positioned anywhere in the aircraft Without regard to the location of the control unit, and hence should be so situated within the available space as to achieve the most efllcient operation of the antenna that is possible. The reel is provided with an emergency hand crank 13 by means of which it may be rotated manually in the event that the drivin unit should for any reason become inoperative.

Also secured by screws tothe member 12 is the casing "M of the driving :unit. This casing is subdivided into tour compartments 15, 136, H and 78, three of which are separated from one .another by a pair of vertical partitions l9 and Bil, the fourth (compartment 13) being separated from the first two but communicating with the The core is fixed rigidly to one end of (compartment Tl). Access may be had to compartments T5 and 16 by removing a cover M which is attached by screws to the top of casing 1 1. Access maybe had to compartments ll and it by removing a cover 82 which is attached by screws to the front side of casing 14.

Within compartment T! is a fiat plate 83 mounted on the partition 80 by means of screws. A portion 84 of this plate is bent outwardly at right angles to the remainder and forms a support for a pair of

electrical contacts

85 and 86. Also within the same compartment is an electrical contractor :8 which is controlled by a discshaped cam 88 securely fastened to one end :of the rotatable shaft 89. This cam is :made of insulating'material.

Three

electrical contacts

90, 91 and :92 are mounted in operative relationship with com 88, supported on appropriate insulators 93 which are positioned :at equal intervals around a circle concentric with said cam. Each of the contacts comprises a pair of superposed springs spaced apart at one end by an insulator 9.4. The three bottom springs (i. e., those which are mounted nearest the partition 80) are arcuate in shape; each of the top springs has :a corresponding arouate portion and, at its free end, a radial portion 85 which extends inwardly to .a point underneath cam :88 where it :is-embossed to present a generally dome-shaped surface to the cam. The latter springs are tensioned toward the cam so that the boss on each spring engages the underneath face o f said cam. This face is divided into two seg orients 8G and 91, one raised :and the other recessed. As the-cam is rotated, the raised segment 96 depresses each top spring in turn, maintaining it depressed until the rotation of the cam brings the recessed segment 91 over the radial portion of that spring, whereupon the spring restores due to its own tension. During the period that it is thus depressed, each top spring engages its assoslated bottom spring. Preferably, one or both springs will .be :provided with a small, preciousmetal contact at :the point of engagement. It will be seen that during rotation of the cam the three contactssfl, 9.! and 82 are closed in sequence and that each, when closed, remains closed While the cam rotates through an angle of approxima-tely 200. This :angle may be altered, of course, by changing the proportions of the two segments of the cam, but 200 has been found to give very satisfactory performance.

A pair of receptacles or

jacks

98 and 99 are mounted in one wall of a compartment 18. All electrical connections to the driving unit are made over two cables: the ten-conductor cable 21 which has a plug lllfl insertable into jack 98 and a battery cable H]! which has a similar plug insertable into jack 99. The wiring between the jacks .and the various contact springs in compartment I? has been omitted from Fig. 1.2 for the sake of clarity but it will be appreciated that the electrical connection conform with the circuits shown in Fig. 16.

Secured to the one end of the casing 14 by means of screws is a reversible, series-wound, di rect current motor M2 which has a built-in electromagnetic clutches shown in cross-section in ll. The driving element H13 of the clutch is firmly attached to the shaft I04 of the motor,

and supports a ring -J05 of non-magnetic friction =i;naterial. This ring has one face conforming with the cone-shaped portion of the driven element I08. The latter element is free to slide axially on the shaft I09, but a pin IIO extending through shaft I09 and having it ends in appropriate slots or keyways in the driven element prevents any rotary displacement between the two. The drivingelement, the driven element, and

, the casing of the motor are all formed of suitable magnetic material. Within said casing is mounted a coil I I I which when energized attracts the driven element I08 toward the driving element I03, the principal path of the flux being indicated in Fig. 11 by the heavy dotted line. This causes the driven element to slide along the shaft I09 against the force of the light spring I'I2 until the conical portion thereof engages the ring I05. While thus engaged any rotation of themotor shaft I04 will drive the element I08 and hence produce a'corresponding rotation of the shaft I09. Upon deenergization of the coil III, the spring II2 forces the driven element away from the driving element and brings the conical portion into engagement with the face of the stationary braking member H3. This-quickly halts the rotation of theshaft I09.

The rotation of shaft I09 which occurs when the clutch is engaged and the motor is running is communicated to the shaft H4 by a pair of spur gears H5 and IIS securely fastened to the respective shafts. A key II! in shaft II4 causes the worm H8" to turn with said shaft, and this (through the worm wheel II9) rotatesthe shaft 09. As previously pointed out, cam 88 is firmly attached to one end of the shaft 89. A chain drive I having a sprocket at'the other end of shaft 89 links said shaft with the antenna reel TI the ratio of the sprockets being such'that two revolutions of shaft 89 will cause but a single revolution of the reel.

It should be noted that the key II! in keyway IZI of the worm II8 (see Fig. 15) permits said worm to slide in an endwise direction on the shaft I I4 although preventing any rotary displacement between the two. On one end of the worm and integral therewith is a disc I22 which hereinafter will be referred to as the out limit disc. A second disc I23 which will be called the in limit disc is slidably mounted on shaft II4 adjacent to the same end of said worm. The

helical spring I24 urges the in limit disc to the left, normally holding its collar against the end of key II? a shown in Fig. 15; a lighter helical spring I25 between the in limit disc and worm II8 urges the wormto the left. Movement of the worm to the left, however, ordinarily is opposed by a force resulting from the weight of the fish I26 attached to the end of the antenna I21. Assume, for example, that the antenna is partially reeled out. Due to the weight of the fish (plus, of course, the weight of the extended portion of the antenna) there is a tangential pull on the reel tending to rotate the reel (and hence shaft 89) in a clockwise direction. It will be seen from Fig. 13 that, because of this tendency, the worm wheel H9 urges the worm to slide to the right along shaft II4. This force is suificient to overcome the light spring I25, thereby bringing the out limit disc into engagement with the in limit disc, but is not great enough to overcome spring I24, since the initial compressive strength of the latter spring is greater than the force produced by the rotational pull of the antenna. Accordingly spring I24 maintains the in limit" disc where it is shown in Figs. 11 and 13, this being the position in which its collar is in contact with the key II! as shown in Fig. 15.

Under special circumstances which will be set forth more in detail presently, the worm will slide along shaft H4, either in one direction or the other from the position in which it is shown in Figs. 11 and 13. When it slides to the left (such movement being limited by the collar of spur gear IIB which acts as a stop) the out limit" disc engages a bushing on the lever I29 urging it to the left. This makes the shaft I30 to which the lever I29 is rigidly fixed rotate in a clockwise direction, whereupon the arm I3I, also fixed to said-shaft, rotates in the same direction, causing the electrical contact 85 to close. A second lever I33 similar to the one just described has its shaft I 34 passing through the partition 80 adjacent to shaft I30 of the first lever. When the worm IIB slides to the right along shaft II4 it displaces the in limit disc against the force of spring I24 ntil said disc is stopped by sleeve I35. On such movement, the in limit disc engages a bushing on lever I33, rotating this in a counterclockwise direction and hence causing the arm I3! to open electrical contact 86.

Mode of operation (outline) Having described in detail the structure of the control unit and of the driving unit for the reel, the manner of their operation will now be explained briefly, attention being directed particularly to Figs. 1 and 4.

It will be assumed that an aircraft equipped with the two units is in flight and that the pilot or radio operator wishes to extend the antenna. To do this, he throws the switch lever 52 to its out position, which immediately operates the magnetic clutch associated with motor I02 and causes said motor to begin to turn the reel II in a clockwise direction to unreel the antenna. At substantially the same time, the driving mechanism also causes the tell-tale lamp 5? in the control unit to light, thereby indicating to the operator that unreeling' has begun. As unreeling progresses, the contactor 8'! in the'driving unit transmits electrical impulses to the three-gang motor in the control unit, causing the latter to operate the Veeder counter in such a way that, for each revolution of the reel, the counter will add'one unit to the reading visible through window 5|. At the start of unreeling, this reading is 000, and hence at every instant thereafter it will show the exact number of turns of antenna which have been unreeled.

As already indicated, the optimum performance of the aircrafts antenna system will occur on a wavelengthwhich is proportional to the length of antenna trailing the aircraft; therefore it is self-evident that the operator ordinarily will not wish to extend the whole antenna, but only a certain length, that length being the one whose operation is optimum on the wavelength which he intends to use for radio communication on this particular occasion. Knowing how much antenna he wants extended, the operator will watch the dials on the Veeder counter as the driving mechanism pays out the antenna, and when the counter indicates that the desired number of. turns have been unreeled, he will bring the mechanism. to a halt by restoring the switch lever 52 to its "ofi'position. This manual operation stops the motor I02, releases the magnetic'clutch and causes the three-gang motor to stop operating the Veeder counter; it has, howfore remains lighted as a positive reminder to the operator that a portion of the antenna is extended.

While the antenna is thus extended it may be used in the conventional way for radio communication, it being assumed that the aircrafts radio transmitter is coupled to the antenna in some suitable manner, such as, for example, via a con. nection (shown dotted in Fig. 4) to the small metallic trolley wheel which engages the antenna at a point intermediate the reel and the fairlead.

, Assuming now that the operator has finished the radio communication for which he extended the antenna, he will throw the switch lever 62 to its in position to retract the antenna once more. .This again operates the magnetic clutch and initiates the operation of motor I02, the latter now rotating in such a direction as to turn the reel II in a counterclockwise direction. Con tactor 81 again transmits electrical impulses to the three-gang motor in the control unit causing'this motor to rotate the shaft of the Veeder counter in the reverse direction, whereby the counter subtracts one unit from its reading for each revolution of the reel as the antennais reeled in. When the fish I26 at least enters the mouth of the fairlead, the driving mechanism automatically stops itself, halts the operation of the,,Veede r counter (which now will have been restored to normal, i. e., its 000.position) and causes the lamp 51 to be extinguished.

. Although ordinarily operating in the above way, the driving mechanism can, under certain abnormal conditions, refuse to unreel the antenna eventhoughthe switch lever 62 is thrown to its out position,- These guarding arrangements will be made clearpresently.

Detailed operation (reeling out the antenna) this displacement, but it is unable to force the displaced members to theleft on shaft H4 .because to do so it would have to rotate worm wheel H9 in a counterclockwise direction, such rotation being prevented by the fact that the fish 26, isalready pulled into the fairlead as far as .it will go and will not permit the reel (hence the worm wheel) to turn further in said counterclockwise direction. I

In order to reel the antenna out, the operator throwsswitch 611 to its on position and leaves it there, as already indicated. This switch at contact I40 thereupon closes the following circuit for operating the motor" I 02 in the direction indicated-by arrow A: positive battery, conductor HI, contacts I40 and 69, resistor I42, conductor I43, winding I, motor I82,-andnegative battery. At the same time the clutch is operated over the following circuit: positive battery, conductor; MI, contacts I 40, 69,.and I45, conductor 14$, winding II I, and negative battery. With the clutch operated andthe motor turning in the direction indicated byarrow A thegear H begins to rotatewith its top coming toward the observer. .Accordinglythe gear H6 (and hence the. worm H8) rotates'with its top going away from the observer.

When the, worm rotates in this direction, it necessarily follows that one of two things must happen: Either the Worm will begin to screw itself to the left on shaft I I4 (assuming that the worm wheel H9 remains stationary and acts as a rack for the worm) or else the worm wheel 'I I9 will begin to turn in a clockwise direction (assuming that the rotating worm remains in its original position on shaft II I). Were it not for spring I24 urging the worm to the left it i clear that the latter would happen, for the antennas tangential pull on the reel due to the weight of fish I26 tends to rotate the worm wheel in a clockwise direction and, at the same time, tends to hold the rotating worm in its original position on shaft 1 I4. However, as already pointed out the compressive strength of spring I24 which urges the worm to the left is greater than the force resulting from the rotational pull of the antenna which urges the worm to the right; accordingly, upon commencing to rotate, the worm at once begins to screw itself tothe left along shaft I I4 under the influence of spring I24. This spring obviously will keep the in limit disc I23 in contact with the out limit disc I22 as it moves to the left and, through worm IIB, it also exerts on theworm wheel sufficient force to prevent the latter from rotating in a clockwise direction.

Themovement of the members along shaft H4 continues until the worm and the two discs reach the position in which they are shown in Figs. 11 and 13. At that time the collar on the in limit disc I23 comes into contact with the key II'I (see'Fig. 15) which prevents the spring I24 from urging the members further to the left. Being no longer overpowered by the pressure of the spring I24, the rotational pull of the antenna nowbecomes effective to start the reel and worm wheel II9 turning in a clockwise direction, as they would have done at the outset except for thepresence of said spring. It should be understood that the fish I26 is sufficiently heavy to turn the reel and the worm wheel at as high a speed as the rotating worm will permit. In effect, .then, the weighted antenna unreels itself, the worm functioning as a motor-driven governor or escapement which merely controls the speed at which suchunreeling takes place. The tangential pull of the antenna on the reel is, of course, present throughout the whole time that the antenna is unreeling, and it is this force, transmitted to the worm through worm wheel H9, whichurges the worm to the right, maintainingthe out limit disc in contact with the fin limit disc as seen in Figs. 11 and 13.

It willbe appreciated that the mass of the reel H and of the antenna wound thereon is so distributed as to give the reel considerable inertia, and that, accordingly, an appreciable interval will elapse before the fish I 26 can accelerate the reel from. a state of rest to its full speed. At the beginning of this brief interval the rotating worm will continue to screw itself to the left along shaft H6, but as the reel gains speed the worm will be returned to the right until it finally reaches the position shown in Figs. 11 and 13,

where it remains throughout the balance of the unreeling process, as indicated above. This slight axialmovement of the worm during the period that the reel is accelerating represents atransient condition which, if not carefully controlled, is capable of bringing about a highly undesirable result. If, for example, the worm moves to the extreme left on shaft II4, the out limi disc I22 will rotate the lever I29, closecontact 85, and at once halt the mechanism by operating relay'88, as-will be made clearer from the ensuing description; To prevent such'action, the resistor I42 is included in the circuit for motor I02 for the purpose of limiting the motors starting torque; this insures that the shaft II4 will not reach an excessive speed before the rotation of reel H is initiated, and hence limits the distance whichthe worm will move to the leftduring this transient period, thereby preventing the out limi disc from closing contact 85.

- Returning now'to the initial axial movement of the worm and limit discs (i. e., that movement whichtakes place before the antenna begins to unreel) it will be seen that when the in limit disc moves to the left it causes the lever I33 to rotate in a clockwise direction, closing contact 88. This contact completes the following 'circuit: positive battery, contact 86, conductor I41, lamp 58, conductor I48, and negative-battery, therebylighting lamp 58 in the control unit to indicate that the driving unit has started to operate as a result of the operation'of switch 60. The closing of contact 88 also completes preenergizing circuits for the-field coils 38, 39- and lfl'of the three-gang motor; The preenergizing circuit for winding 38 extends from positive battery 'over contact 88, conductor [81, winding 38, resistor i l-9, conductor I48, tonegative battery. Similar circuits for

windings

39 and 40 extend over the resistors I50 and i5! respectively. It should be noted, however, that resistor I5I is short-circuited over a path which may be-traced from nega-' tive battery, via conductor I48, resistor IEI, conductor I58, contact 90 of the contractor (this being shown schematically in Fig. 16- as a metallic cam 88 having an insert I52 of insulating material).,back to negative battery; accordingly themotor winding 30 is connected directly to the battery in the following circuit; positive battery contact 88, conductor- I iI, winding 40, conductor I53,,.contact.90, and negative battery. v

The resistors I09 and 150 in series with

windings

38 and 39, respectively, maintain the current flowing through these windings at'a low value, whereby the

stator pole. pieces

32 and 33 are magnetized onlyslightly. The pole piece-34 on the other hand is strongly magnetized, since there is no, resistance in series with windingflll; but, because the rotor element 41 is already positioned directlyacross the open ends of this pole piece, there is no tendency for-the shaft H to rotate.

With the. windings of the three-gang motor thus energized as a result of the in limit disc moving to the left and closing contact '86, the worm wheel II 9 now begins to turn in a clockwise direction under control of the rotating worm as already explained, and hence theantenna begins to unreel. Cam 8, driven by the worm wheel', also begins, to, turn in a clockwise. direction and soon causes contact 9| to short-circuit resistor I59. Therefore the motor winding 38 is connected directly to the battery in the following circuit: positive battery, contact 86, conductor WI, winding 88, conductor I54, contact 9|, and negative battery. This obviously increases the flow of current through winding 38, and consequently the pole piece 32 (now stronglymagnetized) attracts the rotor element diturning the shaft 4| .in a clockwise direction. Were it not for thefact that thepole piece 80 is also strongly magnetized at this time, it isapparent that the shaft would be across the open ends of that-pole piece.

rotated 60 from its initial position (i. e., the amount which would align the rotor element 45 directly across the open ends of the pole piece 32) actually, however, the shaft will 'not rotate more than 30 because the attraction of the rotor elements 45 and 'l-by their respective pole pieces becomes equal at that point.-

As cam 88 continues to rotate, it next opens the circuit extending over contact 90, whereby the motor winding 40 is now is energized only by current reaching it over its preenergizing circuit which includes the resistor I5I. The resultant drop in the magnetization of pole piece 34 permits the shaft 4| to rotate an additional 30 in a clockwise direction under the influence of pole piece 32 which still is strongly magnetized. Rotor element 45 now is aligned directly acrossthe ends of pole piece 32, and it will be clear that shaft 4I'has rotated a total of 60.

While it has been indicated that this rotation takes place in two equal steps, it should be mentionedthat in actual practice the first step may be slightly less than 30 and the second step slightly more. The exact point at which the 60 rotation is divided will depend somewhat upon the magnitude of the load on the three-gang motor, and therefore varies slightly with changes in the viscosity of the bearing lubricant at different altitudes. Since the dividing-point in all cases approximates a 30 rotation very closely, no error will result if it is assumed, for the purpose of this description, that in the above case and all similar cases the two steps which make up the 60 rotation are equal. I I

As cam 88 continues to rotate it next causes contact 92 to short-circuit the-resistor I50 whereby the motor winding 39 is connected directly to battery over following circuit: positive battery, contact 88, conductor I41, winding 39, conductor I55, contact 92 and negative battery. Consequently pole piece 33 becomes strongly magnetized'and attracts the rotor element 46 this tends to turnthe shaftI through an additional 60 in a clockwise direction'but-because the pole piece 32 still is strongly magnetized at this time the rotation again is limited to 30 as explained before. Next, the rotating cam 88 opens the circuit extending'over contact-9I,-thereby causing the motor winding 38 to be energized only by current reaching it over its preenergizing circuit. Since'pole'piece- 33 nowis the only one strongly magnetized, it isable to rotate theshaft an additional 30 bringing the rotor element 48 directly Shaft 4| now. has rotated a total of 120 From the preceding description it will-be clear that the cam 88-, by continuing to turn in a clockwise direction under the influence of the worm wheel'I I9 as the antenna unreels, next will short-circuit resistor I5I over contact 90 (thereby causing'the pole 'piece' lll to be strongly magnetized) and then will interrupt the short-circuit 'of resistor I50 which extends over contactj 92 (thereby reducing the ,magnetization of pole piece 39). At each of these times the shaft 4| will bejtlirne d an additional30? in a clockwise direction.

While rotation ofshaft III thus takes place in increments of 30, itshould not be assumed that the shaft comes to. a complete stop. aftereach 30 rotation; actually thefield

windings

38, 39 and 40 are energized in such rapid sequence .that the momentum of the rotating system of the three-gang tendsto sustain the shafts movement between successive 30 steps. This, together with,

the fact that the" field windings are never completely deenergized. makes the motors operation considerably smoother than would otherwise be the'case.

As long as the. antenna continues tounreel, the three-gangmotor will continue to operate inthe manner described; its mode of operation will be made somewhat clearer by reference to the fol-' lowing table which shows the status of the field coils and shaft of the three-gang motor at the end of each successive 60 rotation of the cam 88 throughout the first three complete revolutions of said cam:

Position of cam 88 rela- Field coils which Position of shaft 41 tive toits Fig. 16 posiare completely relative to its Fig. 16 tion energized position 60 clockwise 38 and 40 30 clockwise.

120cl'ockwise 38' 60 clockwise.

180 clock-wiser 38 and 39 90 clockwise.

240 clockwise 39 120 clockwise.-

1,080 clockwise 540 clockwise.

It will be noted from the above that each 120 rotation of cam 88 causes the shaft 4| of the three-gang motor to rotate through. 60. If the cam turns through 240", shaft 4| will turn 120; if the cam turns 360, the shaft will turn 180; and so on, the ratio of the angle of the cams rotation to that of the shaft always being 2:1.

As the antenna unreel's, each revolution of reel 'II' produces two revolutions of the worm wheel H9 and hence two revolutions of cam 88. Cam 88 by its two revolutions produces one revolution of the shaft 4|. Therefore it will be apparent that for every revolution of the reel in a clockwise direction there is a corresponding revolution of the shaft 4l'in a clockwise direction. The counter 50, driven by the shaft 4|, registers each revolution taken by the latter and hence in effect, registers each revolution taken by the reel. If its reading was 000 at the time rotation of the reel' began, the reading will be 001 at the end of the first revolution of the reel, 002 at the end of the second, etc., at every instant indicating the exact total number of revolutions which the reel has made.

With this indication as a guide, the operator may stop the reeling out process at any desired point. To do this he simply observes the counter reading asunreeling progresses, and, when the counter indicates that the desired number of turnsv of antenna have been unwound, he restores the switch 60 to normal, thereby opening the circuit of motor I02 at contact I40 and opening the circuit of the clutch magnet III at contacts I40 and I45. Although the motor I02 may coast for a short interval after its circuit is interrupted, the rotation of shaft H4 is quickly halted due to the driven element of the clutch engaging thebraking member II3 as already explained. This, of course, stops the rotation of worm I I8, so that the worm wheel IIS (and hence the reel H) can turn no further. Cam 88 also ceases to rctate,ha lting the shaft 4| of the three-gan its top coming toward the observer.

motor in aposi-tion. corresponding to the position in which the reel was stopped, whereby the operation of counter 50 stops with an exact registration of the total number of turns of antenna which have been unreeled. All movable parts now are'motionless, the two limit discs remaining in the position shown in Figs. 11 and 13, and lamp 58 remaining lighted as an additional reminder that a portion of the antenna is extended.

Detailedoperation (reeling the antenna in) When the operatoris ready to reel the antenna in, he throws switch 60' toits in position and leaves it there. This at contact I56 completes the following circuit for operating motor [02 inthe direction indicated by arrow 13-: positive bat-- tery, contact 8t",v conductor I t'I, contact I56", con ductor r51 field winding I58 motor I02, and negative battery. At the same time, the follOWlllg circuit is completed for operating the magnetic clutch-z positive battery, contact 86, conductor I47, contact I59, winding III, and. negative battery. With. the clutch operated and motor I02 turning in the direction indicated by arrow B, gear H5 begins to rotate with its top going away from the observer. Accordingly, ear H6 (and hence worm. H8) begins to rotate with When this happens it isobvious that either the worm must screw itself to the right along shaft II'4 (assuming that worm wheel II9 remains stationary) or the. worm wheel. IIS must begin to turn in a counterclockwise direction (assuming that worm remains in its initial position on shaft I I4). Here again, the compressive strength of spring I24 is sufiieient to prevent the worm from moving to the right along shaft II4 (although the drag of the antenna manifestly urges it to do so) and therefore the rotating worm begins to turn the worm wheel- H0 in a counterclockwise direction. This causes the cam 88 to turn in the same direction, and causes the reel to commence winding up the antenna.

Assuming that the counterclockwise rotation of cam 88 starts from the position in which said cam is shown in Fig. 16, it will be seen that, at the start, resistor I5'I is short-circuited, while resistors I49 and I50 are not; accordingly, pole piece 30 of the three-gang motor is the only one strongly magnetized. As cam 88 turns, it first causes contact 02 to short-circuit resistor I50, thereby strongly magnetizing the stator pole piece 33, whereupon the resultant attraction of rotor element 40 causes shaft 4| to turn through 30in a counterclockwise direction. Next, cam 88 causes contact 00 to open the short circuit across resistor I5I. Consequently, the field winding 40 is energized only by current reaching it via said resistor over the preenergizing circuit for that winding, and the resultant drop in magnetization of pole piece 34 permits shaft M to rotate an additional 30 in'a counterclockwise direction (due to the attraction of rotor element 46 by pole piece 33, which still is strongly magnetized). Next, contact 9| short-circuits resistor I49, increasing the energization of winding 38; then contact 92 opens the short circuit across resistor I50, reducing the current flow through winding 39. At each of these times it will be apparent that shaft 4-I rotates anadditional 30, the operation being set forth more in detail in the following table, which shows the status of the field coils and shaft of the three-gang motorat the end of each successive 60 rotation of the cai'n'88 throughout the first three complete revolutions of said cam:

Position of cam 88 rela- Field coils which Position of shai t 41 tive to its Fig. 16 posi are completely relative to its Fig. 16

tion energized position 40 0. 60 counterclockwise... 39 and 40 counterclockw se. 120 counterclockwise. 39 60 counterclockw se. 180 counterclockwise.-. 38 and 39 90 counterclockwise. 240 counterclockwise.-- 38 120 counterclockw se. 300 counterclockwise.. 38 and 40 150 counterclockw se. 360 counterclockwise. 40 180 countreclockw se. 420 counterclockwise.-. 39 and 40 210 counterclockw se. 480 counterclockwise.-- 240 counterclockw se. 540 counterclockwise- 38 and 39 270 counterclockw se. 600 counterclockwise..- 38 300 counterclockw se. 660 counterclockwise... 38 and 40 330 counterclockw se. 720 counterclockwise..- 40 360 counterclockw se. 780 counterclockwise--- 39 and 40 390 counterclockwise. 840 counterclockwise. 39 420 counterclockw se. 900 counterclockwise--. 38 and 30 450 counterclockw se. 960 counterclockwise.-. 38 480 counterclockw se. l,020 counterclockwise. 38 and 40 510 counterclockw se. l,080 counterclockwise. 40 540 ocunterclockwlse.

From the above it will be seen that the three element motor functions the same general .way that it did when the antenna was being unreeled; however, because cam 88 now is turning in a counterclockwise direction, the field coils 38, 39 and 40 become active (1. e., completely energized) in the reverse sequence, causing shaft 4i to turn in a counterclockwise direction, instead of clockwise as it did during unreeling. Accordingly, the 5 reading of counter decreases with each revolution of the reel until it finally reaches 000. Simultaneously, the fish I26 enters the mouth of the fairlead I39, and, being unable to advance into the constricted throat there-of, prevents the reel from rotating further. This halts the worm wheel I I9, the came 88 and shaft 4! of the threegang motor. Worm wheel H9, now being maintained stationary, acts as a rack for the rotating worm, so that the latter screws itself to the right along shaft I I4, moving the in limit disc I23 against the force of spring I24. The in limit disc soon engages lever I33, and turns it in a counterclockwise direction, opening contact 86. This interrupts the circuit for the clutch magnet III whereupon rotation of the worm is quickly stopped. It also opens the circuit for motor I02; for the field coils of the three element motor; and for the lamp 58.

The operator, seeing that lamp 58 no longer is lighted, knows that the antenna is completely retracted and that the mechanism has come to rest with each part occupying the position it occupied before the antenna was unreeled. He may now restore switch 60 to normal, although no harm will be done if he leaves the switch thrown to its in position until he again wishes to reel out the antenna. In any event,'nochange will be produced until switch 60 once more is thrown to its out position, at which time the reeling-out'process will again start, as already described.

It. will be clear that the operator can, if he so desires, stop the reeling-in process at any time before the antenna is wholly retracted. To do this he simply restores switch 60 to normal, which interrupts the clutch circuit at contact I59 and interrupts the motor circuit at contact I56, thus halting the reel. Moreover, having stopped the reel with the antenna still partially extended, he may thereafter initiate rotation of the reel in whichever direction he chooses, by throwing switch 60 either to its in or out position. If he does the former, the circuit for motor winding I 58 will be completed at contact I; if he does the latter, the circuit for motor winding I44 will be completed at contact I40. In either case the-clutch will be reoperated (due, in one instance, to the closing of contact I59, and, in the other, to the closing of contacts I40 and I45). Accordingly the operator may make the extended antenna longer orshorter at will, changing its length as many times as he. wishes before he causes it to be retracted.

Function of the out limit disc If the operator, having thrown switch 60 to its out position to start the mechanism to reel out tendency of the reel to rotate in a counterclockwise direction is transmitted to the worm wheel H9 which therefore urges the worm to the left on shaft II4. It will be remembered that if the worm wheel remained stationary, the worm would screw itself to the left along shaft II4 due to its own rotation, as pointed out earlier, and accord ingly'with this sudden encouragement of worm wheel I I9 to move in that direction the worm does so. Consequently as the out limit disc I22 slides to the left it rotates lever I29 in a clockwise direction, closin contact 85, which thereupon energizes the winding of relay 68 over the following circuit: positive battery, contact 35, conductor I60, relay 68, conductor I48 and negative battery. At contact 69, the relay opens the circuit of motor I02 and also the circuit of the winding III for the magnetic clutch, whereupon the mechanism rapidly is brought to a halt in the manner already described.

In the event that the reeling out ,process is started by throwing switch 60 to its 'out position While the aircraft is on the ground, the mechanism will operate in the usual way until the fish -I 26 comes to rest on the earth. When this happens its weight no longer tends to rotate the reel and worm wheel II 9 in a clockwise direction,

and accordingly there is in the force urging the worm II8 to the right on shaft H4. Under this condition the pressure of the light sprin I25 (see Fig. 15) urging the worm to the left is sufficient to cause the rotatmg worm to screw itself along shaft H4 toward gear H6. The out limit disc quickly operates the lever I29, closing contact and thereby causing relay 68 to halt the mechanism, as" before. Since unreeling stops automatically as soon as the fish strikes the ground, the antenna is prevented from becoming tangled.

Similarly, if the antenna should, while unreelmg, become snagged on some projecting part of the aircraft, of if the fish I26 should become detached from the antenna, there will not be sufiicient clockwise rotational pull on the reel to keep the spring I25 compressed. Under such circumstances, as in the cases already described the spring I25 will cause the rotating worm to move to the left along shaft II4 until the out limit disc I22, by closing contact 85, operates relay 68 and thereby halts the mechanism. In fact, it should be clear that if the rotational pull on the reeldue to the drag of the antenna and fish I26 is reduced materially below its normal value for a substantial reduction any reason, it thereby becomes impossible to op- 'erate, the motor H12 in such a direction as will unwind the antenna further. (Whenever unreeling stops, the operation of the three-gang motor Function of the slow acting relay In most of the cases described in the preceding section it will be noted that the reeling out process was in full swing at the time the out limit disc became operative to prevent the antenna from being unreeled further. Whenever such is true, the inertia of reel H makes it impossible for the reel to come to rest as quickly as shaft I it stops rotating. Assuming, then, that the shaft has been halted due to the operation of relay 68 (which, as explained above, is due, in turn, to a sufiicient reduction in the antennas tangential pull to permit the out limit disc to move to the left) the tendency of the reel to continue rotating will result in a rotation of the worm wheel I :9 in a clockwise direction. This causes the worm and out limit disc to slide to the right alon shaft lit, first compressing spring l25 and then com;

pressing spring I24. Much of the kinetic energy of the reel is expended in compressing these springs, so that when the "in limit disc strikes the sleeve lt'Ei the reel is halted without imposing an excessive strain upon any of the parts. Since the reel now is stationary it will be apparent that the springs will at once return the two limit discs to their respective extreme left-hand positions on shaft H4 (it being remembered that, under the condition assumed, the antenna is not exerting sufficient force on the reel to maintain spring 25 compressed) From these facts it will be clear that after re lay (it has operated and caused shaft IM to halt, its circuit frequently is interrupted at contact 85 for a brief interval, as a result of the reel momentarily sliding the out limit disc to the right. During this interval the relay remains operated due to its slug, and hence maintains the contact 69 open.

The relays ability to absorb this momentary circuit interruption is of considerable importance, for if it failed to do so the circuit for windings l l l and HM would be re-established at contact 69 as soon as contact 85 opened. This would cause shaft H4 to resume its rotation, giving fresh impetus to the rotation of reel H and causing the worm to slide back to the left on shaft I I4. As a result of the latter movement, the out limit disc would again close contact 85, thereby operating relay 68 and bringing shaft H4 again to a halt. No sooner would shaft Ill be halted than would the reel, due to its continued rotation, once more cause the worm and out limit disc to slide back to the right on the shaft. This, by opening contact 85, would again release relay 68, thereby reestablishing the circuits for the motor and clutch with the result that shaft I I4 would again resume its rotation, beginning another cycle substantially identical to the first. An undesirable mode of operation such as this has been found capable of sustaining itself through a suflicient number of successive cycles like the one indicated to defeat the purpose of the apparatus.

Relay 68 successfully prevents this manner of operation by maintaining contact 69 open despite the transitory interruption of its circuit at contact 85. In this way the reel is brought to a swift, sure halt, whereas it otherwise would be alternately accelerated and decelerated over a prolonged period, coming to a stop in a jerky, stutterin fashion which would not only impose considerable stress on the mechanism but would unreel additional antenna contrary to the purpose of the arrangement.

It will be observed that contacts 89 and Hill in series are shunted by a condenser 56! which, in the Well known Way, absorbs any inductive surge occurring when either of these contacts is opened, thereby preventin the surge from creating an are at the opencontact. Likewise, contacts 86 and I E56 in series are shunted by a condenser 162 which inthe same way eliminatesarcing at either of the latter contacts.

Having described the invention, what is considered new and is desired to be protected by Letters Patent is set forth in the following claims.

What is claimed is:

1. In an arrangement of the kind described, an antenna occupying a certain position, a mechanism operative to move said antenna away from said certain position and through a plurality of successive intermediate positions to another position, anelectrical circuit, means controlled by said mechanism for preparing said circuit just prior to said movement, and other means then controlled by said mechanism over said circuit for registering, at substantially every instant during the time that said antenna is moving from said certain position to said other position, the amount by which the position of said antenna has been changed at that instant.

2. In combination, a first member and a second member linked by a yieldable coupling, a motor associated with said first member for driving said first member and hence driving said second member via said coupling, a circuit for starting and stopping the driving of said first member by said motor, thereby to start and stop said second member, each of said members effective to subject said coupling to varying forces in accordance with changes in the motion of that member, said cou-- pling effective to yield in the presence of a certain degree of unbalance in the forces to which it is subjected by said two members, a circuit, means governed by the yielding of said coupling for controlling said last circuit, and a slow relay in said last circuit operated responsive only to a prolonged control of that circuit by said last means for altering said first circuit.

3. In combination, a first movable member, a motor for moving said member, a circuit for controlling the movement of said member by said motor, a yieldable coupling, a second movable member linked to said first member via said coupling, whereby said first member causes said second member to be moved at a speed varying in accordance with the speed of said first member, each of said members effective to subject said coupling to forces varying in accordance with the variations in rate of change of the speed of that member, said coupling effective to yield in the presence of a certain degree of unbalance in the forces to which it is subjected by said two members, a circuit, means governed by the yielding of said couplin for controlling said last circuit, and a slow relay in said last circuit operated responsive only to a prolonged control of that .circuit by said last means for altering said first circuit.

4. In an extensible antenna control system, a rotatable antenna reel, a mechanism for rotating said reel in either direction thereby to extend or retract the antenna, a source of current, a plurality of circuits, means controlled by Said mechanism for establishing a flow of current from said source over said circuits just prior to the extension of said antenna from a retracted position, a

circuits sequentially, and register means under the f joint control of said circuits operated progressively during the extension of said antenna due to said influencing of the current flow i said circuits.

5. In an extensible antenna control system, a

rotatable antenna reel, a mechanism for rotatin said reel in either direction thereby to extend or retract the antenna,a source of current, a plurality of circuits over which current from said source flows whenever said antenna is in an extended condition, register means under the joint control of said circuits, a cam mechanically coupled to said reel and hence rotated whenever the reel is rotated, contact means controlled by said cam for influencing the flow of current in said circuits sequentially whenever said cam is r0- tated, thereby to operate said register means progressively throughout such rotation of said cam, and means operated responsive to the antenna reaching its fully retracted position for interrupting the flow of current over said circuits.

6. In an arrangement of the kind described, an antenna occupying a certain position, a register, a source of current for said register, means for preventing current from flowing from said source to said register so long as said antenna remains in said position, a mechanism for moving said antenna away from said position, and means controlled by said mechanism independently of said antenna for causing a flow of current from said source to operate said register progressively throughout said movement of the antenna by said mechanism.

'7. In an arrangement of the kind described, a movable antenna, a mechanism operative to move said antenna, a register, a source of electrical current for said register, mean for operating said register from said source under control of said mechanism thereby to change the registration progressively throughout the movement of said antenna, and means controlled by said mechanism at the end of said movement for terminating the flow of current from said source tosaid register.

8. In a mechanism of the kind described, a movable antenna having a normal position, mechanism for moving said antenna, means operated when said antenna is at normal for initiating the operation of said mechanism, delay means in said mechanism whereby said mechanism begins to move said antenna away from normal a brief interval after the operation of said first means, a

' motor, means controlled by said delay means during said interval for preparing an electric circuit for said motor, means then controlled by said mechanism upon initiation of the movement of said antenna for starting to operate said motor over said circuit, and a register driven by said motonupon' the latters operation.

EDWARD S. PETERSON.