Патент USA US2407666код для вставки
4 .Sept E7, 1946. c. G. HoLscHuH ETAL „ 2,407,665 AIRCRAFT FIRE CONTROL COMPUTER Filed Aug. 1, 1940 ` /6 5 Sheets-Sheçt 1 l g a - v Q ~ WFH-FEW@ TRANSMITTER GoNSTn/vr :SPEED Moron IN - Carl _l David ENToR ' - l'lolsc 'uh Fr _ l sept. T7, 1946. 2,407,665 c. G..Ho|_s'cHuH ETAL AIRCRAFT FIRE CONTROL COMPUTER Filed Aug. 1, 1940l 47 o.; v 3 sheets-sheet 2 Sept W, 3945 . C. G. HoLscHUH Ei- Al. 2,407,665 AIRCRAFT FIRE CONTROL COMPUTER Filed Aug. 1, 1940 's sheets-sheet 3 F“ E . TARGET WING SPREAD FLIGHT AXIS I -` PROJECTED WING SPREAD INVENTORS CARL G. HOLSCHUH DAVID FRAM +' f ff ï TH EIR ATTORNEY` Patented Sept. 17, 1946 2,407,665 UNITED STATES PATENT OFFICE ì 2,407,665 AIRCRAFT mi: CONTROL COMPUTER Carl G. Holschuh, Wood-Ridge, N. J., and David Fram, Brooklyn, N. Y., assignors to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application August 1, 1940, Serial N0. 349,336 l .6 Claims. (Cl. 235-61.5) This invention relates to apparatus for direct ing gunfire at an aerial target from an attack ing aircraft and refers more particularly to a sighting and computing device adapted to direct gunfire from a high speed pursuit airplane in an 2 The sighting and computing apparatus is pref erably housed in a single housing adapted to be ñXedly mounted on an airplane with the axes of the instrument in fixed relationship to, and preferably coincident with, the axes of the plane. attack on a slower plane, for example, a bomber. The optics of the sighting apparatus comprise a The present invention constitutes a modiñca prism I rotatable in azimuth and elevation in tion of and improvement in the apparatus dis which the line of sight experiences one total re closed in the copending application of Earl W. fiection, a prism 2 in which the line of sight is Chafee, Serial No. 211,550, iiled June 3, 1938, and 10 twice totally reflected, a dove prism 3 rotatable assigned to the assignee of the present inventors, about an inclined axis in which a single reflec which application discloses an automatic sight tion occurs, range ñnding optical wedges 4, 4' and and computer comprising apparatus adapted for eye piece 5. When a target is in the field of view sighting and tracking an aerial target together and a suitable adjustment of the wedges 4, 4' has with range finding means and a computing mech 15 been made, an observer with his eye placed at anism for obtaining from target azimuth, eleva Si sees two separate images of the target plane, tion and range data and the indicated air speed a normal and a displaced image, these images of the attacking plane the proper angle for posi being upright and unreversed as to right-left tioning a gun relative to the line of sight. The components and adjacent Wing tips of the two plan of attack for which the device of the above 20 images apparently just touching one another so application is adapted is one in which the ñring that the center to center distance is equal to the plane having the superior mobility of the two wing spread. The positioning of said two images craft, trails the target on a parallel course and in the just described relationship by the operation at a chosen range which is maintained constant. The present invention provides apparatus of the general character previously disclosed which is not limited in its functioning to a single con stant range but which has means for obtaining and introducing into the computer variable range data and for performing the more complicated computations incident thereto. Another object of the present invention is to provide means for setting up and automatically introducing into the computer a rate of change of range. of the range setting control or controls eifects a range setting, the value of the range so set being introduced into the computing mechanism. The training -of the line of sight on the target in- elevation is accomplished by means of eleva tion (En) displacement knob 'i and elevation rate knob 8 and in azimuth by means of azimuth (Ao) displacement knob 9 and rate knob lil. The motion of elevation displacement knob 'l is trans mitted by spur gears I I and bevel gears I2 to one arm of mechanical differential I3, a second arm of which is connected to shaft I4 which, in turn, Still another object is to provide in apparatus of the above character simplified sighting and range ñnding controls whereby adjustments may is connected by bevel gears I 4’ to one arm of mechanical differential I5. A second arm of diiîerential I5 drives shaft I6 which in turn ro be made and automatically continuing changes tates prism I about horizontal shaft I9’ by means of adjustment set up without shifting the hand 40 of bevel gears I1, worm drive I 8, spur gear Il', from one control member to another. freely >rotatable about tubular member I5', its A further object is to provide apparatus of the meshing pinion I9 and bevel gears I8’. above character which is adapted to be used as Besides the means for tracking the target in a bombsight and also for obtaining a measure of ground speed. Other objects and advantages of this invention will become apparent as the description proceeds. Referring to the drawings, Fig. 1 (in two Parts, Fig. 1A and Fig.lB) is a schematic diagram of an improved sight, range ñnder and computer according to the invention. Fig. 2 is a diagram illustrating the method of computing range. Fig. 3 is a perspective view of the wind resolv ing unit. elevation provided by elevation displacement knob l, provision is made for automatic tracking at al constant rate by rotating prism I from the Output of a variable speed device 23 controlled by elevation rate knob 8. The rotation of knob 8 transmitted to shaft 20, rack and pinion 2IA and push rod ZI’ displaces ball carriage 22 of this device and the position of the balls retained in 'carriage 22 and driven by disc 24, rotated by con stant speed motor 25 by way of shaft 2B, deter mines the speed at which cylinder 2l rotates, this 55 speed being proportional to the displacement of 2,407,665 4 cned View of the target where the path of the target is offset from that of the pursuit plane, the angle in azimuth the line of sight takes with arriage 22 from the center of disc 24. The mo ion of cylinder 21, introduced into a third arm f differential i3 by way of gearing, results in a reference to the longitudinal axis of the pursuit ontinuous rotation of shaft i4 and hence of prism about its horizontal axis at a rate proportional CW craft is introduced. Wingspread knob E5 rotates a three-dimen o the displacement of knob B. Knobs 1 and 8 are sional cam 64 in accordance with target dimen voaxial and are arranged on their shaft and sleeve, sions. The cam is translated by means of gear yespectively, so that they may be grasped simul and rack mechanism 61 which is controlled by aneously with one hand. This is of considerable mportance since by “double gripping” an oper ttor with practice can adjust both the. displace 10 gears 5E on shaft 35, the angular displacement nent and rate of change of the line of sight with iut having to shift his hand from one control :nob to another. In order to prevent disturbing of shaft 35 being proportional to the azimuth angle of the line of sight measured from the lon gitudinal axis of the aircraft. Cam 64 is laid out so that when actuated as just described its '.he position of rate knob 8 whenv displacement 15 lift pin is displaced in proportion to the product of target dimension and the cosine of the angle rnob ‘lis turned, a detent 23 is provided acting Ythe line of sight makes with the fore and aft in shaft 2E). Also to prevent rotation of the dis line of the aircraft. The lift pin displacement -Jlacement knob by a feed-back of the motion of thus obtained, when divided by the product of ;he cylinder 21 through differential I3, a fric ;ion brake 29 is provided on the displacement 20 the sine of the angle through which the prisms are turned and a constant C is equal to range as drive which provides friction loading for the arm explained in detail in the above-mentioned co 3f the differential to which the displacement pending application. The latter operation is ac control is connected, As above mentioned, training of the line of sight on a target in azimuth is accomplished by rotation of azimuth displacement knob 9 and rate knob l0. The rotation of knob 9 is intro duced into one arm of mechanical differential 30 by way of spur gears 3l and bevel gears 32, while the output or the motion of a second arm of said differential is transmitted by gearing to shaft 33 and thence by Way of bevel gears 34 to shaft 35 and by another pair of bevel gears 35 to shaft 31. Motion of shaft 31 through gear ing 3E! rotates prism l about a vertical axis. In order to prevent the azimuth motion from af complished byV means of cam which is trans lated by lift pin 53 of cam 64. Cam 6G is rotated by long pinion 5i and gear 62 driven from shaft 5l which is displaced by a range rate mecha nism described further on. The lift pin of cam 6E! is used to effect the range adjustment of the optical wedges, the cam being so laid out that the movement of the lift pin is proportional to the sine of the angle through which the wedges are displaced and the required rotary movement of the cam for this displacement is equal to slant range, Do. Coaxial range displacement and range rate knobs are provided which enable the operator to make range settings in the same man ner in which elevation and azimuth settings are made. The motion of range displacement knob diiferential I5 which functions as a compensat ing or “unwinding” differential. The rotation of 40 41 by means of spur gears 43 and bevel gears 49 is introduced into mechanical differential 5o by shaft 31 also rotates prism 3 by means of gears fecting the elevation setting, the motion of shaft 31 is transmitted by gearing to a third arm of 38’ and thereby prevents the change of position of the image which would otherwise be caused by the rotation of prism l. Azimuth rate control way of one arm and a second arm of the differ into diiferential 30 by Way of a third arm and appears at the output as a rotation of shaft 33, motion is introduced into a third arm of differ ential 50 and appears at the output as a rota ential is connected by gearing to shaft 5l. Ro tation of range rate knob 52, transmitted by way of shaft 53 and rack and pinion 54, displaces ball is obtained by an arrangement similar to the ele carriage 55 of variable speed device 55 having vation rate control. The movement of azimuth disc 51 driven from constant speed moto-r 25 by rate knob lo is transmitted by shaft 39 and rack way of shaft 26 and gearing 58. Cylinder 59 of and pinion 45 tov ball carriage 4| of variable speed device 56 has imparted to it a rate of ro speed device 42. This> device has a disc 43 driven by constant speed motor V25 by way of shaft 26 50 tation proportional to the displacement of ball carriage 55 from the center of disc 51, which and a cylinder 44 whose motion is introduced this motion being combined by the differential with the rotation of displacement knob 9. A detent 45 is provided on rate setting shaft 39 and a friction brake 46 on the displacement drive tion of shaft 5|, the differential combining this motion with that of displacement knob 41. The relationships of the quantities entering into the computation of range are shown dia grammatically in Fig. 2. It is assumed that the wing spread of the target is known by the oper ment settings, as described in connection with 60 ator of the device. In practice he will be pro the elevation rate control. vided With a table of wing spreads. Range may The method of determining range by means therefore be computed. from the projection of of oppositely rotated optical Wedges is fully de this wing spread perpendicular to the line of scribed in application No. 211.550, previously re sight and the angle (0) subtended by this pro ferred to, and only the present means for eifect ing this rotation will be here described. It is 65 jected wing spread at the sight. Since 6 is usu ally a small angle, range (Do) is taken to be assumed that a dimension of the target, for in equal to projected wing spread divided by 0. Pro stance, wing spread, is known. This value is set jected wing spread is obtained from actual tar into the sight by adjusting wing spread knob 65 get wing spread by multiplication by the cosine with reference to a suitable scale, not shown. of the azimuth angle (Ao) between the flight As described in the above-mentioned applica axis and the line of sight. t is assumed that tion, slant range Do is equal to the target wing the longitudinal axis of the craft coincides with spread divided by the product of the sine of the the flight axis, that is, that no side drift occurs. angle through which the optical wedges are dis To simplify the figure, since 0 is small, Ao is placed and a constant C. Shown as the angle between one side of 6 and the In order to take into consideration a foreshort prevents interaction of the rate and displace 5 2,407,665 flight axis. An approximation of negligible im portance is made in showing the base angle of the small right angle triangle which includes wing spread as equal to Ao. The motie-n of shaft 5|, representing slant range of the target (Do), is transmitted by bevel gears 69 to shafts 'I9 and '||, the former of these two shafts feeding range to azimuth prediction cam 'I9 and by Way of the latter shaft to eleva tion prediction cam 12. 10 The means by which motions proportional to the azimuth, elevation and slant range of the tar get are introduced into the computer have been described. From the rates of change of these quantities and from ballistic data for the projec tiles used, the deflection angles of the gun in ele vation and azimuth are computed, that is, the angular offsets between the line of sight and axis of the gun bore in two perpendicular planes. Each deñection angle is considered as being made up of two parts: (1) the predicted relative an gular motion of the target during the flight of the projectile from the gun to the target, and (2) the angular offset necessary to compensate for change of trajectory of the projectile due to “wind” acting upon it during its time of flight. The “wind” which deflects the projectile both in azimuth and elevation is considered to be the rel index on said dial to match a corresponding index on a dial 89 actuated by air speed indi cator 99. The motion of knob 87 is introduced into air speed resolving unit 9| by way of shaft 92, bevel gears 93, one arm of mechanical differ ential 94 and shaft 95. This resolving unit Oper ates on> the same principle and may be similar in construction to the resolving unit described in aforementioned application Serial No. 211,550. Fig. 3 of the present application is similar to Fig. 2 of said prior application and illustrates the con struction of the resolving unit, The resolving mechanism as a whole is ori ented in azimuth from gun azimuth shaft 96, whose positioning vn‘ll be laterdisclosed, by way of bevel gears 91, shaft 98 and worm 99 meshing with teeth on the periphery of disc or gear 9| ' on which the mechanism is mounted. The two com ponent velocities into which the air speed is re solved are those in the horizontal plane across and along the line of fire. Shaft 95 which is angularly displaced in accordance with the air speed, turns shaft |16 through worm drive |15 to position rack bar Il?, by means of pinion |16’ engaging a rack thereon, proportionally to air speed. rThe plate | 'll' on which bar |'|1 is mount ed is movable in guide |l'8' secured to the face of disc 9|’ and rotating therewith. Plate |11’ ative velocity of the airplane and the air and is has a hole engaged by a pin |78 on slider |79. taken as numerically equal to the indicated air 30 By a. connection to differential 94 the displace speed (IAS) shown by an air speed meter, ment of shaft 98 is combined with that of shaft For computing the first part of the elevation 92 to remove the effect of the turning of disc 9|', deflection angle, rod l2', which is connected to in azimuth, upon the position of shaft 95 and ball carriage 22 and has a displacement propor hence upon the radial position of rack bar |'|'|. tional to the rate of change of elevation angle, 35 Differential 913 functions as a compensating dif is lcaused to translate three-dimensional cam 'l2 ferential. The-slider |19 is mounted for trans and this cam is rotated in accordance with slant verse movement in a lateral slideway in the ver range (Do) from shaft ‘1| through bevel gears tically movable T-shaped member |39 through 'i3 and pinion 'I4 meshing with a gear on the which extends an elongated pinion |8| mounted cam. The prediction component 'of the eleva 40 on shaft |83 and meshing with rack teeth |82 on tion deflection angle is equal to the rate of change the rear of slider HS. -Up and down movement of elevation angle multiplied by the time of flight of member |89 is transmitted to a pinion |84 (T) of the projectile, and since this time may meshing with rack teeth |85 on the rear thereof, be taken as a function of range (Do), cam 12 is the pinion being mounted on shaft lill. It will positioned according to D@ and En rate to obtain be apparent that the horizontal wind velocity as the lift of the follower T5 the prediction angle, introduced from shaft |76 is resolved into two that is, components, which, due to the orientation of disc 9|’, are head wind and cross wind, referred to the line of ñre. These components are both _ functions of the azimuth angle Ag through which This displacement is introduced by means of rack and pinion 'F6 and shaft 'Il into one arm of me chanical differential 18, a second arm of which is driven in accordance with the second part of the deflection angle, that is, the ballistic correc- " tion, determined in a manner described herein after. The azimuth prediction component of the total azimuth deflection angle is obtained in a man disc 9|’ is turned. The head wind or horizontal component of the air speed along the line of fire is obtained as a rotation of shaft |99, geared to shaft |83, while the component across the line of lire is taken from the resolving unit as a ro' tation of shaft IUI. Shaft |99, through rack and pinion |92, translates three-dimensional cam |93 which is rotated in accordance with gun or quadrant elevation (corrected for departure from level by means to be described) from shaft |04, Whose positioning will also beV disclosed later. ner similar to the elevation prediction by trans (it) lating three-dimensional cam 19 in accordance with rate of change of azimuth angle from push Cam | 03 is so laid out that the lift of its follower rod 8i) connected to ball carriage 4|. This cam m5 represents the ballistic correction at a fixed is rotated in accordance with slant range (Do) range as a function of wind velocity and eleva from shaft 70 by way of bevel gears 8| and pinion tion angle and to introduce the further factor of 82 which meshes with a gear 0n the cam. The lift of cam follower 83 is the azimuth prediction angle which is introduced into one arm of me chanical differential 84 by way of rack and pin variable range, cam pin |05 translates a second three-dimensional cam M36 which is rotated in accordance with slant range (Do) by shaft |97 driven from shaft -5| by bevel gears I B8. The O lift of cam follower |99, positioned by cam |06, ion 85 and shaft 86, a second arm of said differ ential receiving the azimuth ballistic correction. is the elevation ballistic correction taking into For computing the ballistic corrections in ele vation and azimuth, indicated air speed (IAS) is introduced into the computer by turning air account head wind, quadrant elevation and range. This lift is converted into a rotation by means of rack and pinion |||l and introduced speed knob 81, geared to a dial 88, to cause an 75 into mechanical differential 'I8 by means of bevel 2,407,665> 7 8 follower |53 which is positioned by a second three-dimensional cam |52. Cam |52 is rotated gears ||| actuating one arm of the differential, where it is combined with the elevation predic from shaft lil? by way of p-inion |93’ and a gear tion introduced by shaft 'l1 and the combined on the cam in accordance with gun elevation (Eg) displacement positions one arm of mechanical (corrected for departure of the sight from a Cn differential H2, a second arm of which is posi level condition) and is translated in accordance tioned by cylinder l|3 of variable speed device with range (3D0) from shaft |61 by way of rack Hä, this speed device functioning as a torque and pinion i511. The lift of follower |5| on cam ampliñer. läíl therefore combines functions of cro-ss Wind, Torque or force amplification is desirable at and range and represents azimuth bal this stage of the computing operation since the 10 elevation listic correction which is fed by way of rack two components of the deflection angle (predic and pinion |56, shaft |55, bevel gears |51 and tion and ballistic corrections) are obtained as shaft |5d into differential 64, Where it is com lifts of cam followers and these followers nor bined with the azimuth prediction angle to give mally can exert insufñcient force to drive the total azimuth deflection. succeeding elements of the computing mecha 15 theFor supplying suñicient torque to position suc nism. The action of the variable speed device ceeding members in accordance with total azi l ill as a torque amplifier is as follows: Disc ||5 is muth deflection angle, variable speed device |39 driven at a constant speed from motor 25 by is connected to operate in a manner similar to way of shaft 28 and gears lit. The elevation variable speed device lid and receives the com 20 prediction angle introduced into differential T8 bined azimuth prediction and ballistic correction as the displacement of shaft 'El and the eleva angles from differential 3ft by way of differential tion ballistic correction intro-duced into the same US5 and transmits this motion as a displacement differential by way of bevel gears HI are addi of shaft HH, bevel gears |42 and shaft |43 to tively combined by the differential and intro duced into one arm of differential ||2 by gear 25 mechanical differential |124, where it is added to the present azimuth of the target, introduced Hl. A second arm of said differential is con nected to cylinder H3, while the resultant dis placement of the third arm is transmitted by means of rack and pinion H8 and displaces ball carriage H9. Increasing displacement of ball 30 carriage il@ from a central position causes cyl inder l i3 to be rotated at an increasing rate un til the rotation of the differential shaft mount ing gear lll’ is at the same rate as that of the shaft mounting gear lil’ by means of which the combined prediction and ballistic corrections are introduced into differential it?. The angular displacement of shaft |25), mounting gear |28’ into differential It@ from shaft 33 by Way of bevel gears M5 and shaft |45. The output of differen tial ifiëë representing the sum of the present tar get azimuth and the azimuth deilection angle, i. e., the gun azimuth (Ag), is transmitted by shaft ¿it to high and low speed gun azimuth transmitters H38 and líiû, respectively, rotating relative to one another at the ratio of gears |41. As in the case of the elevation transmitters, these transmitters are preferably of the self-synchro nous or “selsyn” type adapted to actuate self synchronous receivers |48’ and Mil' at the gun or guns through suitable transmission lines. meshing with gear H1', therefore represents the The theory of operation of the computer in 40 total angular correction, and since the power for computing ballistic correction angles is based on driving shaft |20 comes from disc H5 by way of the assumption that the axes of the optical sys the balls of ball carriage ||9 and cylinder H3, tem are truly horizontal and vertical. The effect a considerable load may be imposed upon this of head Wind, for example, is computed as a func Shaft |20 by way of bevel gears |2| and shaft f; tion of the elevation of the gun from the hori zontal~ If the craft is climbing or diving, its |22 drives one arm of mechanical differential longitudinal axis is tilted relative to the hori |23, a second arm of which is driven from shaft zontal and the elevation angle fed to the ballistic Ul by way of bevel gears |2¢l and shaft |25. lThe computing cams, which is an angle measured sum of the motions of shafts |25 and |"| ap relative to the craft, cannot be used directly for in) pears as the rotation of shaft |26 driven from ballistic correction computation. A correction the third arm of the differential. Since the factor must be introduced and means for intro motion of shaft I4 is proportional to the present ducing this factor are provided by level knob elevation angle of the target, the addition of §32 geared to ball level indicato-r |33, having an the prediction and ballistic correction angles, i. e., arcuate tube |34| adapted to be rotated about a the elevation deflection angle, causes the dis horizontal axis parallel to the craft’s lateral axis placement of shaft |26 to be proportional to the by rotation of knob |32` When the ball indi angle at which the gun should be elevated (Eg). cator |3¿l’ is not centralized, thereby indicating The displacement of the shaft |25 is trans that the longitudinal axis of the craft is not hori mitted by way of bevel gears |21 and shaft |23 zontal and therefore that the sight is not level, to high and low speed gun elevation (Eg) trans the rotation of knob §32 necessary to bring the mitters |29 and |35, respectively. The relative ball to a central position is transmitted by wal7 motion of these transmitters is in a ratio deter of shaft |35 and bevel gears |3ä5 to mechanical mined by the ratio of spur gears ISI, for exam differential |31, where it is added to the gun ele ple 36:1. These transmitters are preferably of shaft.V the self-synchronous type, that is “selsyn” trans mitters, connected by transmission lines to self synchronous receivers |29’ and |39’ by means of which elevation data is indicated at the gun 260. vation (Eg) entering the differential from shaft i218 before the combined motion is transmitted to the ballistic cams by shaft |04 and thereby nism 9| as the displacement of shaft lill and three-dimensional cam |50 is rotated in accord ance therewith. This cam is translated by cam If the sight is not level as shown by the posi tion of the ball of level indicator |33, the opera tor ûrst introduces a correction for this condi corrects the settings of these cams. It is assumed as before noted that the craft’s longitudinal axis For obtaining the ballistic correction in azi- ' coincides with the flight axis, which is the axis . along which relative wind acts. muth, the cross wind or wind component across rl‘he operation of the device is as follows: the line of fire is derived from resolving mecha 9T 2,407,665 tion by rotating level knob |32 to bring the ball indicator |34’ back to a central position, and by this operation sets into the ballistic correction computing mechanism a compensating displace ment by way of shaft |35, bevel gears |36 and differential |31. Upon sighting the target, it is assumed the operator will be able to identify the type of plane 10 may then be caused to remain stationary in the iield of view by setting in the proper elevation rate, from which ground speed may be calculated when altitude is known. As many changes could bc made in the above construction and many apparently widely diiîer ent embodiments of this invention could be made without departing from the scope thereof, it is and from a table of values furnished him the intended that all matter contained in the above wing spread will be found. This value of wing 10 description or shown in the accompanying draw spread is set into the computing mechanism by ings shall be interpreted as illustrative and not rotation of knob 55. At this time a further nec essary preliminary operation is the matching of in a limiting sense. Y Having described our invention, what we claim the pointer on dial 88 with the pointer on dial and desire to secure by Letters Patent is: 89 of air speed indicator 9|). The operator then 15 1. Apparatus for compensating for the effect estimates the target azimuth and elevation an gles, or a iirst approximation of their values may be obtained from the pilot of the craft Who has before him crossed lines on the front window to of wind on a shell ñred from an airplane mount ed gun comprising sighting and computing means for determining a line of ñre to a target which consists of gun elevation and gun azimuth angles, aid in estimating these angles. The approximate 20 means positioned according to indicated air angles are set by means of elevation displace ment knob l and azimuth displacement knob 9, speed, resolving means actuated thereby and ac cording to the indicated gun azimuth angle for respectively, Upon looking through the sight, obtaining a measure-of component airspeed in the target should then be in the ñeld of view a direction perpendicular to the vertical plane which, in a preferred form of the invention, may 25 of the gun axis, means providing a measure of have an angular value of 18°. target range, a mechanism actuated in acord rl‘he target will normally appear to be moving ance with the elevation angle of the gun in said across the field of view and in order to maintain plane and said measures of component wind and the image or images centralized, the operator will range for computing a windage correction to the normally ñnd it necessary to manipulate both 30 azimuth aiming angle of the gun, means for regu displacement and rate knobs, which may be done lating the windage correction in proportion to in the present arrangement by “double gripping” deviation of the airplane from a level course, and owing to the proximity of these two knobs and means automatically correcting the azimuth an their coaxial arrangement, With practice, al gle for the gun relative to the line of sight in though manipulated by one hand, the tWo knobs 35 accordance with said regulated windage correc may be turned independently to a limited but tion. suiiicient extent. If a target is moving at an 2. In apparatus for applying a Windage cor apparently steady rate across the field of view, rection to the indicated elevation aiming angle the setting up of suitable elevation and azimuth of a line of ñre of an airplane mounted gun dur rates will maintain the image centralized once 40 ing substantially level flight of the plane, means it has been brought to this position by manipu positioned in accordance with the indicated azi lation of t-he two displacement knobs, When the muth aiming angle of the gun relative to a nor target image remains centered with respect to mally horizontal axis of the plane, means posi the cross hairs of reticle E', the operator sets the tioned in accordance with a measure of the air range by operating range displacement knob 4l 45 speed of the plane as representing relative Wind until the Wing tips of the two target images velocity eiîective in deliecting a projectile fired touch, as described in aforementioned applica from the gun, means receiving azimuth angle tion No. 211,550. and wind velocity from the first two means and When the range has been set, the mechanism supplying a measure of the horizontal component is in a completely operative condition and correct 50 of wind velocity along the line of ñre, means posi aiming data is supplied to the gun or guns from tioned in accordance with the indicated gun ele elevation transmitters |29 and |30 and azimuth vation angle, means providing a measure of tar transmitters M8 and |49, When range varies, a get range, means receiving said horizontal com constant rate of change of range is set by rotat ponent of Wind velocity, gun elevation angle and ing knob 52 and by “double gripping” the two 55 target range from said several means to eiiect range knobs lll and 52, the operator will be able automatically an offset of the indicated and gun to keep the two images of the optical range finder angle in elevation, which compensates for the in their predetermined relative positions indica joint effect of said last three received quantities, tive of a _correct range setting. and means for varying the gun elevation angle Any error in the azimuth and elevation angles 60 received by the last-mentioned means in propor transmitted to the gun or guns is directly re tion to inclination of the longitudinal axis of the flected in ñring errors, whereas an error in range airplane to correct said oiïset when the airplane introduces only a secondary error in the ballistic is not on a truly horizontal course. and prediction corrections. 3. An apparatus according to claim 1 in which By suitable adjustment of the elevation, azi 65 said mechanism is actuated by means comprising muth and range iinder controls, the apparatus a dilîerential having a plurality of input arms, of the present invention may be used to obtain one of which is displaced in proportion to the in a measure of ground speed and also to establish dicated gun elevation angle, and another in pro certain of the angular relationships necessary for portion to the inclination of the longitudinal axis aerial bombing, Thus, to use the apparatus as a 70 of the airplane. ground speed measuring device the line of sight 4. In apparatus for applying a windage cor is directed vertically downward by rotating prism` | about its horizontal axis, and a suitable azi rection to the indicated azimuth aiming angle of a line of fire of an airplane mounted gun dur muth angle is set in by rotating the prism about ing substantially level -ilight of the plane, means its vertical axis. Images of terrestrial objects 75 positioned in accordance with the indicated azi 2,407,665 11 muth angle of the gun relative to a normally horizontal axis of the plane, means moved in accordance with the airspeed of the plane as representing relative wind velocity effective in de ?lecting a projectile fired from the gun, means receiving said azimuth angle and Wind velocity from said ñrst two means and supplying as a function or” said two quantities a measure of the horizontal component of wind velocity across the line of nre, means positioned in accordance with indicated gun elevation angle, means providing a measure of target range, a mechanism receiv ing said wind component, gun elevation and tar get range from said several means and actuating wind correcting apparatus for altering the azi muth- aiming angle of the gun in accordance with a function of said three received quantities, means for indicating the inclination of the lon gitudinal axis of the airplane on departure from level flight», and means adjustable according to the inclination indicating rneans for Proportion ately varying the gun elevation angle received by said mechanism whereby a corresponding cor rection in the azimuth aiming angle is effected. 5. In an inter-plane iire control device for an airplane. mounted gun, a sight having members determining a line o-f sight, means controllable at the sight for simultaneously indicating the angles for. guidance in positioning the gun- i-n azimuth 12 automatically relatively offsetting the indicated gun elevation position angle and line of sight in accordance with said computed correction an gle, and means for regulating the magnitude of the elevation angle in proportion to the inclina tion of the longitudinal axis of the firing air plane. 6. In an apparatus for directing fire from a gun mounted on an aircraft and aimed at a tar get thereby' deñning a line of fire, a computing mechanism comprising a îirst three-dimensional cam, means for positioning said cam in one di mension controlled in part in accordance With indicated gun elevation (Eg), means for con-tinuously positioning the cam in another dimeni sion in accordance with slant range (D0), the last-mentioned means including a variable speed device and a control therefor for obtaining an adjustable constant rate of change of range, a follower for said cam, the cam being so laid out that the lift of the follower is proportional to a ballistic function of elevation and range, a re solving uni-t having an output member, means for adjusting the unit in one sense according to a measure of wind velocity relative to the craft, other means for adjusting the unit in a different sense in accordance With indicated gun position in azimuth whereby the output member is dis placed in proportion to the horizontal component of wind velocity across the line of ñre of the gun, and elevation deíining a line of ñre and for 30 a second three-dimensional cam disposed so as positioning the line of sig-ht in azimuth and ele vation, means moved- in` accordance withv a meas urev of airspeed of the ñring crait, a computing mechanism having means controlled in accorde ance with indicated gun` azimuth and elevation angles and range and the means for setting wind in accordance withv the measured airspeed, said mechanism furtherl including means for deriving from said azimuth and wind settings a head wind component along the line of ñre and for comput ingV a wind correction angle in indicated gun ele... vation as a function of said head wind, range, and said elevation angle, together with means to 15e displaceable in one dimension by the fol lower of the iirst cam, and in another dimension by the output member of the resolving unit, a follower for the second cam,l said cam being so laid out that its follower is adjusted continuously in proportion to the azimuth correction for the wind component across the line of fire, and gun angle transmitting means operatively connected with the last-mentioned follower. CARL G. HOLSCHUH. DAVID FRAM.