NOW 5,1946. ~ H. c. VAN AUKEN ETAL 2,4Í0’468 BOMB SIGHT Filed April 9, 1941 5 Sheets-Sheet 2 l . » uur' ` EN oRs, Ham-wo C’. l/mv w/E/v 0, Feâpfe/ck N. 55H52, p " l ` ` " nu’ ? „ _ Tusm ATTORNEY . ' Nov. 5, 1946. 2,410,468 H. C. VAN AUKEN ET_AL BOMB SIGHT Fì1ed.Apríl 9, 1941 5 sheets-sheet s 77ML- or FALL I INVENTORJ, ?/.C VmvAu/a-w ma Y Ell/.551152, ¿47 EIR- ATTORNEY - NOV- 5, 1945 y _ ' H. c. VAN AU'KENy ET AL > BOMB SIGHT - " 2,430,468 ' Filed April 9,l 1941 - 5 sheets-sheet 4 INVENTQRS HOWARD c. vAN AuKx-:N F DERICKN. ESHER `*'LIFRYAÍK' , _ Nov. 5, 1946. 2, 410,468 H. C. VAN AUKEN ET AL BOMB SIGHT Filed April 9, 1941 5 Sheets-Sheet 5 jF-IE. INVENTORS HOWARD C. VAN AUKEN FREERICK N. ESHER ` THEIR ATTORNEY.` ` Patented Nov. 5, 1946 2,410,468 BOMB SIGHT Howard C. Van Auken, Bloomfield, and Frederick N. Esher, Rutherford, N. J., assignors to Sperry Gyroscope Company, Inc., Brooklyn, N. Y. , a corporation of New York Application April 9, 1941, Serial No. 387,574 6 Claims. (Cl. 244-76) 1 . This invention relates to improvements in the art of bomb sights for aircraft which are designed to direct the course of the craft so that its ground tracks, except for odset, would pass through the target in a straight line and which determine the exact point at which the bombs should be dropped to strike the target. rï‘his mechanism also pref erably computes and sets in automatically the 2 « Fig. 5 is a plan View of the same. Fig. 6 is a side elevation of the two-scale time of flight dials which are shifted from one position to theother for low altitude and for high altitude bombing. Fig. '7 is a diagram illustrating the trigonometry of bombing. The optics of the present invention are sub stantially the same as shown in the aforesaid prior amount of offset necessary to compensate for side drift due to side winds. 10 application Ser. No. 375,900. According to this The general principles of such sights are well system, the reticle I of the system (Fig. 1B) is sta understood in the art and this invention con bilized in all planes by being mounted on the top stitutes improvements in certain elements there of a suitable form of gyrc-vertical 2 which, in of, whereby simplification is secured as well as turn, is mounted on a platform 3 stabilized in improved operation. More particularly, our in 15 azimuth by remote control from a directional gyro vention constitutes improvements in the method ' «i (Fig. 2). The line of sight, after passing down . in the type of sight shown in the prior patent toV E. W. Chafee and H. C. Van Auken (one of the present joint inventors), No. 2,162,699, dated June 20, 1939, for Bomb sights. . Another improvement consists in further de 20, wardly through the telescopic sight 5 and through the reticle, is reflected by a mirror 6, thence by a prism 'l to a prism 8,'and thence to a, target fol lowing prismv 9. The latter is shown as pivoted on the gimbal ring Ill of the gym-vertical so as to be stabilized about fore and aft trunnion axis il, and it is tilted through the angle 0 to follow the target by means of a bell-crank lever I.2 which velopment of plural scale sights designed t0 op 25 is moved from the sight angle cam I3. The prism l, on the‘other hand, is turned around a Vertical erate efficiently at more than one altitude range, axis to impart the offset angle F to the line of such as shown in the prior application of H. C. sight by means similar to that shown in the afore Van Auken and G. N. Hanson, ñled January 25, said prior application and comprising, brieñy, a 1941, Serial No. 375,900. ' long bell-crank lever I4 pivoted on axis l5 and Another improvement consists in the tie-in be having its horizontal arm I4’ adjusted up and tween the azimuth gyro, automatic pilot and bomb down by the cross trail mechanism I6 to swing sight, whereby the same directional gyroscope in the Vertical arm Il about the pivot I5 and thereby the automatic pilot may be utilized both for steer rotate the curved -lever i8 and turn the shaft I3 ing the craft and for stabilizing the optics in azi to which prism l is secured, as explained in the muth. ' aforesaid application. Referring to the drawings illustrating our in The time of fall is preferably set into .the mech~ vention in diagrammatic form, anism by adjusting the time of fall fine and coarse Figs. 1A, 1B and 1C are a diagrammatic per dials 29 and 3B (Fig. 1C) from charts prepared in spective layout of the elements of the invention, in which the three figures taken together repre 40. accordance with variable bomb characteristics sent a complete diagram. Fig. 2 is a similar diagram illustrating the auto matic pilot portion of the invention with its con nections to the bomb sight. Fig. 3 is a wiring diagram illustrating the prin cipal electric connections involved, in simpliñed form. Fig. 4 is a sectional View, on a larger scale, of the special dual variable speed device for intro and altitude. A knob 2l! is used to set in this time, said knob rotating a shaft 2l which rotates fine dials 29 through worm and worm wheel Iûû’ and shaft I?l , and rotates coarse dial 30 through screw 45 gears |02, reduction gearing IilS and shaft Illli’. Shaft 2l also has a thread IM thereon, threaded in a ball `carriage 22 between a cylinder 23 and a.> disc 24, thereby moving the carriage radially to and from the center of the disc. 'I'he cylinder 23 50 is normally rotated at a constant speed from av motor 25 through a suitable gear train 26 and a change speed gear 27 controlled by push knob 28. In one position of the knob„the cylinder is driven into the mechanism, both for low altitude and at a relatively slow speed from the motor 25 for high altitude bombing. 55 high altitude bombing, and in the other position at 2,410,468 and 43 is positioned a spring pressed roller Si and 6l’ so as to maintain the disc iirmlyagainst the bells of each ball carriage and ñrmly against the is shifted. ln either position of knob 28, there fore, it will be seen that the dise 2d will be driven from the motor 25 at a rate dependent upon the radial position of the ball carriage 22 over the disc, as determined by the time of fall setting of dials E@ and 3i) through knob 2B. Preferably, two dials are provided for both coarse and ñne readings .t0-3B' and 29-29’, one pair Sii-29 being read when the device is ad justed for the high altitude range and the other Sfr-29’ for the low altitude range by the Vknob 28. ïn order that the proper dials only may be visible at one time, we have shown a connection from the knob 23 to masks 3l and 32 on the two sets of dials. Said connection is shown in the 4 rality of guide rollers Eil. Also, on the opposite side from each of the adjustable ball carriages 22 a higher or multiple speed for relatively low al titude bombing, so that by shifting from one posi tion to the other, the range scale of the machine respective cylinders 23 and 64. Tilting of the disc is prevented by additional rollers B2 and 52’ on the bottom thereof and positioned at right ~ angles to the rollers el and >6 l ’. l’n normal operation, after the sight is placed on the target through knob '56, the ground speed (G. S.) knob fili is »adjusted until the sight is kept continuously on the target. When this is accom plished, the radial position of the ball carriage (i3 on the dis-c represents whole range (PF1) (Fig. 7) with reference to the altitude ratio H) T17 form of a pin 33 on the back of a clutch shifting fork 34 on the shaft 28’ of knob 28 which pin 20 of the machine, the variable speed mechanism solving the equation engages a slotted arm 35 pivoted at 36 (Fig. 6) A and carrying at its upper end a gear sector 3'! meshing with an annular rack bar 38. Said bar is pivotally connected at each end to the two masks Si and 32, In the position shown in Fig. 6, only the upper dials 29 and 30 are visible through the rectangular windows 39, 39’ in the two masks, which are in this position aligned with the layer rectangular windows 4Q, dii’ in the outer cover iii of the instrument. When, how ever, the knob 28 is shoved to the right in Fig. 1C, pushing the pin 33 to the right in Fig. 6, the masks will be rotated to the left, moving the windows S9" out of alignment with the win dows fit, fiil’ and moving the lower windows 42, ft2’ into alignment with the windows 40, lill', thereby concealing the upper dials 29, 3l! and ren dering visible the lower dials 29' and 30’. It will be understood that the two sets of dials 29, 29’ and 3i), are graduated differently for the dif 25 The adjustment of the knob riß is therefore trans mitted through bevel gears 63 and shaft 64 to ro 30 tate the whole range shaft 65 which rotates, through universal coupling ëíì, the threaded shaft El Said shaft 51 is threaded in a bomb release Contact device 58 so as to position the same in ccordance with the whole range (FP1). The trail correction (PiT) is shown as intro 35 duced from a knob ’iQ having a trail scale 'El thereon which is set in accordance with tables from the known altitude air speed and terminal velocity of the bomb. Said adjustment rotates a shaft 'E2 through worm and worm wheel 73 and 40 also rotates a spur gear 'iti which meshes with a ferent altitude ranges. As stated, as knob 2t is adjusted, it also ad justs the radial position of ball carriage 22 on disc 2li, so that the disc 2li will be rotated in in 45 verse proportion to the time of flightV (T) or pro portional to l T Driven from said disc is a second ball carriage 50 ‘t3 which is also radially positioned over the sur face of the disc and drives a cylinder 44 at a variable speed dependent both on 1 55 collar V'lâ rotatably but non-slidably mounted on theshaft :'ìl' and having on its periphery a-circu' lar rack. Therefore rotation of the spur gear 14 will move contact block 68 longitudinally inde pendently of the rotation of the screw shaft 61 to introduce the trail correction. A cooperating contact 16 is shown as secured to a rack bar 11 positioned from a gear 'i8 on the shaft lâ of the range angle @am i3 so that, `as the range angle cam rotates, it will finally advance the contact i5 into contact first with the warning contact E8’ and then the final bomb release contact 68". The setting of the trail mechanism also longi tudinally positions a cam »pin Si! on a three dimensional cam 8l which is positioned rota tionally in accordance withl a function (the tan gent) of the range angle 0 and is so laid out and the radial distance of the ball carriage 43 that the lift of the pin is proportional to Y cos from the center of the disc 24 (Figs. 1C, 4 and 5). 6, where Y represents the trail (PiT). Hence the The radial position of said ball carriage is con trolled from shaft 45’ threaded in said carriage, 60 cam is shown as rotated from the shaft '19 and the range angle cam I3 through bevel gears 82. which in turn is rotatably adjusted from a ground The lift of the pin 80 governs the tilt of the long speed and range setting knob llt on shaft lil, lever M9 of the cross trail linkage through cam having a gear £8 thereon meshing with a pinion surface I6 in a manner similar to that disclosed lill on »shaft fifi. The rotation of the cylinder 44 ' in the aforesaid application No. 375,900, to finally drives a shaft 50 which positions the sight angle tilt the arm |74’ of the bell-crank lever M to cam i3 through train of gears 5l, differential '52, thereby rotate the prism l to introduce the cross gearing 53, shaft 513 and worm and worm gear 55. trail angle F. As explained in the aforesaid ap A direct and quick positioning of the sight angle plication, the cross trail angle F is proportional cam may also be obtained from the knob 5S , through gearing 5l and the other arm of the 70 to Y cos 6 sin D, where D is the drift angle, and the latter is set into the mechanism by knob differential 52. |43, which is turned to bring the drift angle rI‘he preferred detailed construction of the indicator |44 into the position indicated by the variable speed drive is shown in Figs. 4 and 5. index §45 driven from a shaft M5, in turn posi The driven disc 2li, as shown, has no central shaft but is rotatably guided at its periphery by a plu 75 ltioned from the shaft 98 which turns the optics 2,41 0,468 5 6 in azimuth, away from its normal fore and aft turns, through gears H5, the shaft >|03 directly, ~ position and which therefore represents the drift angle. Rotation of the knob |43 operates to shift laterally a rack bar |41 which carries the pivot pin |48 of a lever |43. ' In orderto adapt the machine to be used also at high altitudes, the bar TI is also provided with an additional contact '16’ adapted to en gage alternative bomb release contact block |03. Said block is also mounted on a threaded sha-it 6l’ which may also have swiveled thereinV a circular rack sleeve 15', similar -in lfunction to the rack sleeve 15, for introducing the trail from slipping the cylinder under the ball carriage. ‘ - At the same time that the optics are turned, we dudit preferable also to turn the :craft either through the automatic pilot or through the human pilot who observes the pilot director in dicator |39. Preferably, a two-speedv drive is interposed in these connections so that the craft may either be turned at the same rate as the optics or at a greater rate, which latter is dee sirable when the correct course is beingsought for. To this end, the shaft |03 is shown as driv ing a shaft || 6 leading to the automatic pilot the spur gear 14’ on shaft 12. The threaded through change speed gearing H1. AV three-` shaft 61’ is shown as rotated through a universal 15 position clutch H8 controls the rvariable speed. coupling 66' from a shaft 83 »also driven from gear. In the central or open position, as 'indi the shaft (i4,r but at a slower speed than shaft cated in Fig. 3, the shaft H6 stands still, but 65, as through` direct- bevel gear connection 8e. when pushed to the left in Fig'. 1C (up inFig. Referring now to the wiring diagram in Fig. 3), the shaft ||6 is rotated at one speed, while . 3, it will be seen that when the switch S is 20 when pushed to the right in Fig. A1C (down vin rotated counter-clockwise, the contacts on bomb Fig. 3), shaft ||6 is rotated at a multiplespeed. release block 68 will be in control, while when The higher ratio is automatically rendered ef vrotated clockwise, release block |03 will be in fective when the sight is being uniformly turned control to actuate the bomb release solenoids at a predetermined rate from the knobz |09, 85. Preferably the switch S is connected to and When knob |09 is turned, it lifts a switch block directly operated from the knob 28 (see Fig. 1C) H9 out of a notch |20 in a cam |2|, thereby so that when the scale of the machine is changed closing the back contact |22 (Fig. 3) and there by pushing the knob from one position to the by exciting a clutch winding (not shown) to other, the switch S is also moved to connect draw the armature downwardly in Fig. 3 or to the proper switch block into the circuit with the 30 the right in Fig. 1C. The unit ratio, on the release solenoid.. other hand, can only be. put into operation when As stated above, the optical unit is preferably the block ||‘9 is in the notch, thus closing front maintained iixed in azimuth from a suitable di contact |23, and also when a separate switch |24 rectional gyroscope. `¿l and preferably also the is closed as shown in Fig. 3. Preferably, also, we entire aircraft is automatically steered from a 35 interpose an interlock between knobs |09 and |-|li directional gyrcscope, preferably the same direc so that the latter cannot be moved except when tional gyroscope 4 which serves as a directional the former is in its zero or inoperative position, reference. A diagrammatic layout for accom i. e., except when switch H9 is in notch |20. For plishing this purpose is shown in Fig. 2. The this purpose, we have shown. a locking detent directional gyro 4 is shown as having a two-part 40 |60 on one end of a lever |6| pivoted at |62 and inductive pick-oli" associated therewith, one part loosely Ipinned at its- opposite end to switch "_bar having three windings 80, 86’ and 81 shown as H9 so that said detent is pressed into engage attached to the vertical ring 90 of the directional ment with the teeth on elongated pinion |64 gyroscope and the other part being a soft iron when the bar H9 is raised. The elongated pin bridge 89 attached to the follow-up member 88. ion l5@ is» ñxed to gear H5 thereby preventing Such pick-olf is well known in the art and the turning of the knob lili when. a- rate of turn is A. C. signal therefrom is ampliiied in an amplifier set into the machine through operation oi knob 9| to actuate reversible follow-up motor 92. Said |08. As shown in the drawings, the displacement motor is shown as driving, through reduction knob ~||fl may slide with elongated pinion |64 gears 93 and slip clutch 94, the shaft 95 which to disconnect the gear | I5. This prevents the drives the follow-up gear 88 on the gyroscope shaft |03 from becoming locked when detent and also `runs to the bomb sight, where it is |60 engages the pinion |613. ' ' shown as connected through a clutch 93 to one The shaft 95 may bef entirely disconnected arm of a diiîerential gear train 91 to the vertical from the optics by pulling a` knob |25y to the right shaft 98 driving, through bevel gear 93, a shaft 55 in Fig. 1C. This also operates the switch S’ for |00> which is shown as turning the base of the controlling the erection rate of the gyroscope, gyro-vertical through skew gear |0|'. By this as more fully explained in the prior application means the optics are stabilized in azimuth. of E. W. Chafee andv H. C. Van Auken, Serial For displacing the optics in azimuth to direct No. 128,034, iiled February 26, 1937, for Bomb the line of sight on the target and thereby set 60 sights, the erecting winding being shown in Fig. up the drift angle D, the other arm of the dif 3 at |29 and the resistance controlling the erec ferential 91 is turned from a gear |02 on the tion rate at |30. shaft |03 of a cylinder |04, forming one element As hereinbefore Stated, the sight may be used> of a variable speed drive AVSD, the disc |05 of either with the automatic pilot or without, de' which is continuously driven from the motor 25 65 pending on the position of theswitch |73| `(Fig. through a suitable gear train, as shown. The 2. When the switch is in the down position, position of the ball carriage |08 may be radially the rudder servomotor |32 is controlled through adjusted by means of the azimuth rate knob amplifier |33 from a signal generator ,|34-v |09 which turns, through gears H0 and |||, a geared to shaft 95. This Signal generator is pinion ||2 meshing. with rack teeth H3 on car preferably in the form of a Selsyn transmitter riage |08. By this means the proper rate of (Figs. 2 and 3) in which both the armature and. turn of the optics may be set up to keep the neld are rotatable. As shown, the y.field |35 is lineof sight on the> target. If desired, a direct rotated from the shaft» 95 while the armature setting of the optics may be `obtained from an |35 is mounted on va shaft v| 31 rotated from the aiuriliaryazimuth displacement knob H4- which 75 follow-back. shaft ~| I6. When used with the auto» 2,410,468 7 8 matic pilot, only the three windings of the. field said follow-up system, a visual pilot director, a repeater motor normally actuated from said transmitter for turning said pilot director, a rud der servomotor for controlling the heading of the aircraft, and means for transferring the output are connected to a Selsyn signal generator (not shown) in the amplifier |33, which gives a, signal proportional to the angular displacement of the generator and transmitter. When, however, the switch |3| is in the up position in Figs. 2 'and 3, said windings |34 of the ñeld are connected to corresponding windings on the Selsyn repeater motor |38 which operates a pilot directing indi cator |39, which may be synchronized with the transmitter by means of a knob |40 operating to adjust the ñeld of said repeater. In Fig. 2, the rudder servomotor |32 is shown in the form of a hydraulic cylinder and piston |4| which oper ates the rudder |42 of the craft. The sight angle may also be set up directly by a, knob |58 and at tached scale | 5|, which rotates a shaft |52 geared directely through bevel gears |53 to the sight angle shaft 19. From the foregoing it is believed the operation of the bomb sight will be readily apparent. When it is desired to displace the sight quickly to ini tially ñnd the target, for instance, the kno-b H4 is turned with the switch |24 open. After the target is sighted and the pilot is desirous of get ting on the straight ground track toward the tar get, the knob |09 is adjusted. Turning of this knob not only sets up the desired rate of turn of the optics, but also throws switch ||9 to thereby of said transmitter to control said rudder servo motor. 2. In a combined bombV sight and automatic pilot for aircraft, a displacement control member, 10 means actuated by said displacement control member for causing displacement of the line of sight of the bomb sight through any desired angle, means actuated by said displacement con trol member for causing the aircraft to turn 15 through a corresponding angle, a rate control member, and means actuated by said rate control member for causing said two first-named means to turn said line of sight at a selected rate and to turn said aircraft at a faster rate. 3. In a combined sight and automatic pilot for 20 aircraft, a displacement control member, means actuated by said displacement control member for displacing the line of Sight of said bomb sight through any desired angle, means actuated by 25 said displacement control member for causing the aircraft to turn through a corresponding angle, a rate control member, means responsive to said rate control member for setting up a pre determined rate of turn of said line of sight and cause a more rapid turn of the craft through the 30 of the aircraft, and means responsive to move ment of said rate control member from its neutral automatic pilot or pilot director by throwing in the clutch ||8, thereby turning the shaft il@ rapidly to displace the iield of the transmitter |34 at the desired rate of turn. As the ground position for preventing operation of said dis placement control member. track is approached, the azimuth rate is re pilot for aircraft, a manually adjustable variable speed drive having an V.output member for setting duced by turning the knob |89 backwardly until 4. In a combined bomb sight and automatic it becomes zero when the straight ground track is reached, at which time switch ||9 drops into notch |2íl and the turn of both the sight and up respectively a rate of turn of the sight and a proportionate rate of turn of the aircraft for aircraft is stopped. means ' If side wind is present, it is necessary to set in the proper cross trail, which is done by turn ing knob |43 to match the drift angle indicated at |44. This will displace the optics slightly (an gle F), and therefore it is necessary to readjust the same by turning knob ||4| and at the same time to readjust the course through substan tially the same angle. Therefore switch |24 is closed at the time knob ||4 is adjusted, so that target tracking purposes, variable ratio gear driven from the , output member and coupled with the automatic pilot for controlling the turning of the aircraft, a clutch for changing the ratio of the gear means operable by the ad justment of the variable speed drive to zero out 2‘ put rate, and manual means thereupon effective for displacing directly the output member of the variable speed drive to turn the sight and air craft for searching purposes, at a proportionate rate differing from the proportion effective dur the course is also changed through the proper ing tracking. offset angle. When bombing at low altitude, the knob 28 is 5. In a combined bomb sight and automatic pilot for aircraft, the combination with an optical pushed in a direction to expose scales 29’ and Bü’ system rotatable in azimuth on an aircraft of a while, when bombing at high altitude, it is pushed ’ ` manually displaceable member for rotating di rectly said system to position the sight on a target and causing at the same time the turning of the aircraft through said automatic pilot, means for thereafter Ytracking the target comprising a is released in each case at the proper time. variable speed drive having a manual control As many changes could be made in the above construction and many apparently widely dif GO member and an output member operatively con nected with the sight and with the automatic ferent embodiments of this invention could be pilot so as to cause the sight and aircraft to made Without departing from the scope thereof, turn at rates varying in accordance with the it is intended that all matter contained in the setting of the manual control member, interlock above description or shown in the accompanying drawings shall be interpreted as illustrative and 65 means operated by the manual control member in the opposite direction to expose scales 2e and 3i). 'I'his adjustment will change the ratios with in the machine, as explained, so that the bomb not in a limiting sense. Having described our invention, what we claim and desire to secure by Letters Patent is: l. In a combined bomb sight and automatic pilot for aircraft, an optical system, a single di rectional gyroscope for both stabilizing said opti on its initial displacement from a zero output rate position for disabling the manually displace able member, and further means operated by the manual control member on said initial displace ment for changing the relative rates atl which the sight and aircraft are turned. 6. In a combined bomb sight-and automatic pilot for a dirigible craft, a variable speed drive having a control member and an output member, cal system in azimuth and controlling the head ing of the aircraft, a follow-up device at said gyroscope, a connection from said device to turn said optical system, a transmitter driven from 75 a line of sight defining instrument on the craft, 2,410,468 a directional reference, separate means driven by the output member for turning the instrument and also the craft with respect to the directional reference at either of two different relative rates, 10 displaced to turn directly the output member of the variable speed drive to turn the craft and also to position initially the instrument so that the line of sight is on the target, means controlled said means including a two speed shiftable gear 5 by the control member on movement away from mechanism connecting the automatic pilot with its zero output rate position for shifting the gear the output member for controlling the turning of mechanism in another sense to select the other the craft, means for shifting said gear mecha of the relative rates, the control member being nism in one sense actuated by the control mem then used t0 so adjust the variable speed drive ber on being displaced to its zero output rate 10 as to keep the line of sight on the target. position for selecting a predetermined one of the relative rates, a manually operable displacement knob effective when the control member is thus HOWARD C. VAN AUKEN. FREDERICK N. ESHER.