US2694869A

US2694869A - Gun sight trainer

Info

Publication number: US2694869A
Application number: US129217A
Authority: US
Inventors: Eugene M Mcnatt
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-11-25
Filing date: 1949-11-25
Publication date: 1954-11-23
Anticipated expiration: 1971-11-23

Description

Nov. 23, 1954 E. M. MCNATT 2,694,869

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 1 F I I INVENTOR. EUGENE M. McNATT Nov. 23, 1954 E. M. M NATT 2,694,869

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 2 l [30 M F162 JNVENTOR.

; EUGENE M. McNATT ATTORNEY Nov. 23, 1954 E. M. M NATT ,694,

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 5 INVENTOR.

' EUGENE M. McNATT United States Patent 6 GUN srGr-rr TRAINER Eugene M. McNatt, Tulsa, Okla, assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application November 25, 1949, Serial No. 129,217

9 Claims. (Cl. 35-25) This invention relates to a means for imparting angular motion to an apparatus, and for controlling said motion independently of the supporting framework of the apparatus.

More specifically, the invention relates to an apparatus for use in a gunsight trainer, and to a gunsight trainer for the training of anti-aircraft gun crews.

Heretofore, a means for controlling the motion of a simulated target image within a gunsight trainer, independently of the supporting framework of the trainer, has not been known. The desirability of a trainer incorporating such a means has been recognized, however, for the reason that such a trainer could simulate most effectively the conditions which a prospective gunner might meet in combat, since the trainee would be unable to exercise any degree of control over the movement of the simu lated target image.

It is therefore one object of the present invention to provide an improved gunsight trainer wherein the trainee operator does not exercise any degree of control over the movement of a simulated target derived therein.

Another object of the invention is to provide a gunsight trainer in which motion is imparted to a simulated target image by a movable mirror that is situated within the trainer and that is controlled in its movement by a precessing gyroscope, the precession of which is controlled independently of the trainer framework.

A still further object of this invention is to provide a motion imparting apparatus which comprises a gyroscope and a means for applying a precessing torque to the gimbal frame of the gyroscope, said torque being controlled independently of the housing in which the gyroscope is mounted.

Other objects and many of theattendant advantages of this invention will be appreciated readily as the same becomes understood by reference to the following detailed description, when considered in connection with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram of an entire gunsight trainer system which constitutes the present invention; and

Fig. 2 is a perspective drawing showing in detail the construction of the novel gyroscope torque applying means, that is partially illustrated in Fig. 1, and which forms a part of the present invention.

Fig. 3 is a perspective drawing showing in detail the target image movement linkage mechanism that is partially illustrated in Fig. 1.

Broadly, the present invention constitutes a gunsight trainer in which the mechanism for moving the simulated target image is independent of the framework of the trainer and consists of three separate units: an anti-aircraft, optical gunsight 1 which derives a reticle image; a target image 2 that is attached to the gunsight and which comprises a means for generating a target image and a system of gyro-controlled mirrors for focusing the target image and for imparting movement thereto relative to an eyepiece and to the reticle image; and a target image motion control unit 3 for controlling the movement imparted to the target image. Though the gunsight l. and the motion control unit 3 are essential to a proper disclosure of the gunsight trainer, their details do not form a part of the present invention and therefore they have been shown only schematically for the purpose of illustrating their function in the trainer system.

2 The disturbed computing gunsight A disturbed computing gunsight consists of a means for automatically inserting a ballistic correction angle and a proper lead angle between the line of sight of the gunsight, as it tracks a target, and the line of fire of the gun upon which the gunsight is mounted. The gunsight 1 constitutes a disturbed computing gunsight and consists of an image light source 4, a reticle 5, and a collimating lens 6 for creating a reticle image. The reticle image is focused upon a traverse control mirror 7 which has a lever arm mounted in a U-shaped upright 8 that is keyed to the rotor shaft of a traverse rate of swing gyro 7a. The traverse rate of swing gyro 7a is not shown, but has its outer gimbal frame mounted on the gunsight and serves to develop a turning torque that is proportional to the rate of change of azimuth of the gunsight, during the tracking operation. The turning torque, developed by the traverse rate of swing gyro 7a, is transmitted by the proper shafting to the U-shaped upright 8 which rotates the mirror 7 by an amount proportional to, and in the same sense as, the torque developed by the traverse rate of swing gyro; thereby offsetting the reticle image from the line of fire to a target by a proper lead angle in azimuth. Gyro controlled traverse mirror 7 imposes the reticle image upon a semi-transmissive elevation mirror 9, which is rotated in elevation by an elevation rate of swing gyro 9a that is substantially like the traverse gyro 741 but is different therefrom in that its output is proportional to the rate of change in elevation of the target being tracked. The torque developed by the elevation gyro 9a is transmitted to mirror 9 which causes the reticle image to be offset from the line of fire to a target by a proper elevation lead angle. Mirror 9 is a 50% reflecting mirror and is in alignment with a sighting window 10 and a target viewing window 11 so that the gunsight operator, who normally sights through the sighting window 14), has a direct view of the target with the reticle image superimposed when the target is being properly tracked.

The present invention in no way modifies the operation of the disturbed computing gunsight ll except to provide a movable, false target image which can be controlled independently of the gunsight in place of an actual target. The means for doing this are shown broadly in the target image unit 2 and the target motion control unit 3.

The target image uni! Target image unit 2 is attached to the gunsight 1 and consists of a target image source 12, a collimating lens 13, a first reflecting mirror 14- and a second reflecting mirror 15, which serve to derive an imitation target image and to impose the image upon a semi-transmissive, gyro-controlled, movable mirror 16. Semi-transmissive mirror 16 is in alignment with a trainer window 17 and the viewing window 11 and elevation mirror 9 of gunsight It so that the reticle image, that is derived in the gunsight, may he superimposed on the imitation target image depending upgn the relative positions of the mirror 16 and the gunsig t It.

Because the target image unit housing 2 is secured to the gunsight 1, some means for moving the mirror 16 independently of the housing 2 is needed, order to impart motion to the imitation target relative to the gunsight. This means constitutes a part of the present invention and consists of a double-

gimbal gyroscope

21, 18 having a precessing torque applying means mounted on the spin axis of the gyroscope for causing said gyroscope to precess independently of its housing and a linkage mechanism for conveying the movement of the processing gyroscope to mirror 16.

The construction of the gyroscopic, independent motion-imparting assembly and a preferred manner of mounting the same is best shown in Fig. 2 of the drawings, wherein the housing 2 is illustrated schematically as a rectangular frame to which is attached a frame 21. Frame 21 constitutes the outer gimbal frame of the gyroscope and is suspended from the housing 2 by a shaft 22, which is mounted in a free turning gland 23 that allows the gimbal frame 21 to rotate freely in a horizontal plane. Rotatably journaled in the outer gimbal frame 21 is a shaft 24, upon which the inner gimbal frame and rotor housing 18 is mounted, in such a manner that rotor housing 18 rotates freely in a vertical plane. Fixed to rotor housing 18 is a

hollow shaft

25, 26, which constitutes an extension from the spin or rotor axis of the gyroscope, and which has its outer end 26 swivelly mounted on its inner portion 25 by virtue of a swivel joint 28. Shaft 25, 26 also has hole 19 in the outer end thereof that serves as an air jet upon air being supplied to it from the source of compressed air shown in Fig. 1. Air is supplied to the air jet through a conduit 27, that connects from the source of compressed air through a free turning gland 23, and a sealed swivel joint 28 that serves both to supply air to the air jet and to allow the outer end 26 of

shaft

25, 26 to be rotated about the spin axis of the gyroscope by a synchro motor 20. Synchro motor 20 has its rotor fixed to the outer rotatable end 26 of

shaft

25, 26 and its stator fixed to the inner portion of said shaft so that by controlling the thrust produced by the air jet and the direction in which synchro motor 20 rotates the jet, the amount and sense m which the gyroscope precesses can be determined independently of the housing 2. The means for providing this control will be discussed more fully with relation to the target motion control unit.

Actually, as described above, the motion of the air jet and therefore of the simulated target image will not be entirely independent of the motion of housing 2. Because of the manner in which the gyroscope assembly is suspended from housing 2, motion of the housing 2 about its gyroscope spin axis 25 will result in imparting a corresponding motion to the air jet 19 with reference to the earth. Consequently, the direction of the torque applied to the gyroscope is in part affected by motion of the housing 2 about gyroscope spin axis 25. Should it prove desirable to diminish the eifect of any motion of the housing about spin axis 25, a

pendulum assembly

29 and 30 may be added to the mechanism described above. The pendulum assembly is suspended from the inner gimbal frame 18 and consists of two parts, a supporting framework 29 that is rotatably mounted on rotor shaft extension 25 and a pendulum arm 30 which is suspended from the ends of the framework 29. Mounted on framework 29 and aligned with rotor shaft extension 25, in place of being mounted directly on extension 25 as described above, is the synchro motor 20. Thus, any motion imparted to the housing 2 about spin axis 25 is taken up by the pendulum assembly, and the air jet remains fixed relative to the ground.

The linkage mechanism for conveying the movement of the gyroscope to semi-transmissive mirror 16 is best shown in Fig. 3 of the drawings wherein the outer gimbal frame 21 having one of its vertical sides 31 extended to form a support for semi-transmissive mirror 16 is shown suspended from housing 2. Journaled in the outer gimbal frame 21 is a shaft 24 that supports the inner gimbal frame and rotor housing 18, upon which the air jet 19 and synchro motor 20 are mounted. The lower end of the extended side 31 is forked to form a bifurcated journal for a rotatable shaft, that is secured to a bracket 32 which holds mirror 16, and that causes mirror 16 to rotate in a substantially horizontal plane in accordance with the precession of the gyroscope about a substantially vertical axis, i. e. the shaft 22; such precession occurring when the air jet 19 produces a couple on the shaft 25 having a component parallel to the shaft 22 tending to rotate the rotor housing 18 about the shaft 24. The rotatable shaft is extended through both branches of the bifurcated end section of extension arm 31, and a lever arm 33 is fixed to the shaft between the two sections of the bifurcated end section. Inner gimbal shaft 24 is extended beyond the frame 21 and has a similar lever arm 34 attached to it which is properly aligned with the lever arm 33. A connecting rod 35 links the two lever arms together so that rotation of inner gimbal frame 18 causes mirror 16 to be rotated in a substantially vertical plane, in accordance with the precession of the gyroscope about a substantially horizontal axis, i. e. the shaft 24; such precession occurring when the air jet 19 produces a couple on the shaft 25 having a component parallel to the shaft 24 tending to rotate the rotor housing 18 about the shaft 22.

In addition to the imitation target image source and the mirror moving-assembly described in the two preceding paragraphs, the Target Image Unit contains a scoring unit for indicating how well the operator tracks the target image. This unit consists of a collimating lens 36 which focuses the portions of the reticle and target images that do not pass through 50% reflecting mirror 16 on a mask 37 in front of a photocell scoring tube 38; mask 37 being positioned so that Whenever the reticle beam is superposed on the target beam, i. e. whenever the operator is properly tracking the target image, the reticle image passes through the mask and falls upon the photocell scoring tube.

Target motion control unit In order to externally control the amount of turning or precessing torque applied to the inner gimbal frame of the gyroscope by the air jet 19 as well as the direction in which the jet is rotated by synchro motor 20, a target motion control unit 3 is furnished. The target motion control unit is mounted separately from the Target Image Unit and the gunsight 1 and comprises a source of compressed air 40 which is connected to a cam controlled, regulating valve 41. Valve 41 has its valve stem 42 linked to a connecting arm 43 that is driven by a rotating cam 44. Cam 44 can be of any desired shape and is one of a plurality of cams that can be selected by a cam selecting apparatus 45 to drive the connecting arm 43. Regulating valve 41 regulates the amount of air passing to the air jet 19 through conduit 27 in accordance with the shape of the driving cam to thereby cause the gyroscope to precess at a rate which is dependent upon the cam selected.

The direction in which the gyroscope precesses is dependent upon the direction in which the air jet 19 is rotated by synchro motor 20. This direction is determined by a synchro generator 46 which is electrically connected to the synchro motor 20 by conductor 47. Synchro generator 46 has its rotor shafted to a flywheel 48 that is linked to a connecting arm 49 and a rotating cam 59 that is one of a second group of selectable cams mounted in the cam selecting assembly 45. The shape of the cam selected to drive flywheel 48 determines the direction to which the

synchro system

46, 20 rotates the air jet 19 to thereby provide a means for controlling the direction in which the gyroscope precesses.

If desired the air regulating valve 41 and synchro generator 46 may be controlled manually in place of the grseset-cam control provided by cam selecting assembly Operation of the trainer Having described the construction of the Gunsight Trainer, its operation is as set forth hereinbelow. As previously described, the gunsight 1 is normally mounted in gimbal frames on a training stand and can be rotated freely in both the vertical and horizontal planes. The target image unit 2 is mounted on the gunsight with the

trainer window

17 and 50% reflecting mirror 16 aligned with gunsight window 11 and the gyro-controlled, elevation mirror 9. To operate the trainer, a trainee operator rotates the entire assembly consisting of gunsight 1 and the image unit 2 about the stand upon which they are mounted while tracking the target image. The movement of the target image is controlled by an instructor who operates the target motion control unit. The instructor controls the movement imparted to the target image by operating the cam selecting apparatus 45 or alternatively manually controlling the air supply regulating valve 41 and synchro motor 46. As the instructor causes the target image to be moved relative to the eyepiece 17, the trainee operator swings the trainer assembly 2 and 3 in azimuth and in elevation, to thereby track the movement of the target image. The skill with which this operation is performed is recorded by the

photocell scoring unit

36, 37 and 38.

Having described the present invention and its operation, obviously many modifications and variations are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A target simulator for attachment to an optical gunsight to provide a moving target image in the field of view of the gunsight, comprising, a housing, means supported by said housing for providing a simulated target image, a gyroscope having a rotor, an outer gimbal frame and an inner gimbal frame, a vertical axle supported by said housing, said outer gimbal frame being rotatably mounted on said vertical axle, a horizontal spindle rotatably supported by said outer gimbal frame, said inner gimbal frame being mounted on said horizontal spindle, a semi-transmissive mirror pivotally mounted on said outer gimbal frame and upon which said target image is imposed, a mechanical linkage connecting said mirror with said spindle to transmit the rotation of said inner gimbal frame to said mirror, a shaft aligned with the rotor axis of said gyroscope and supported by said inner gimbal frame, an air jet rotatably mounted on said shaft for applying a torque perpendicular to said rotor shaft, and a synchro motor having its stator fixed to said shaft and its rotor fixed to said rotatable air jet, whereby said gyroscope is caused to process to move said target image relative to and independently of the gunsight,

2. A target simulator as set forth in claim 1, further characterized by a reservoir of compressed air, and means for supplying compressed air from said reservoir to the air jet at a varying rate.

3. A target simulator as set forth in claim 1, further characterized by a synchro generator for energizing the synchro motor and means for selectively and variably positioning the rotor of said synchro generator to correspondingly turn the rotor of said synchro motor.

4. A target simulator for attachment to an optical gunsight to provide a moving target image in the field of View of the gunsight, comprising, a housing, means supported by said housing for providing a simulated target image, a gyroscope having a rotor, an outer gimbal frame and an inner gimbal frame, a vertical axle supported by said housing, said outer gimbal frame being rotatably mounted on said vertical axle, a horizontal spindle rotatably supported by said outer gimbal frame. said inner gimbal frame being mounted on said horizontal spindle, a semi-transmissive mirror pivotally mounted on said outer gimbal frame and upon which said target image is imposed, a mechanical linkage connecting said mirror with said spindle to transmit the rotation of said inner gimbal frame to said mirror, a shaft aligned with the rotor axis of said gyroscope and supported by said inner gimbal frame, an air jet rotatably mounted on said shaft for applying a torque perpendicular to said rotor shaft, supporting means mounted on said shaft and maintaining a vertical position with relation to the earth, and a synchro motor having its stator fixed to said supporting means and its rotor connected to said rotatable air jet for rotating said air jet.

5. A target simulator as set forth in claim 4, wherein the supporting means includes a framework rotatably mounted on the shaft, and a pendulum suspended from said frame Work.

6. A gunsight trainer, comprising, an optical gunsight having a sighting window through which the reticle image derived therein can be seen, and an arrangement fixed to said gunsight for providing an imitation target image and for causing said imitation target to move relative to and independently of said gunsight, said arran ement com rising a housing mounted upon said gunsight and having a viewing window which is ali ned with said gunfight-sighting window and through which said gun-sight reticle image can be observed, a movable, semi-transmissive mirror suspended within said housint: in the line of sight between said viewing and sighting windows, an imitation target image source, means for imposing said target image on said semi-transmissive mirror, means moving said mirror relative to and independently of said gunsight and housing including a gyroscope having an outer gimbal frame and an inner gimbal frame, said outer gimbal frame being rotatably supported by said housing so as to rotate freely in a horizontal plane, a shaft aligned with the rotor axis of said gyroscope and mounted on said inner gimbal frame, means rotatably mounted on said shaft for applying a torque perpendicular to said rotor axis, means for rotating said torque ap lying means about said shaft, and means for transmitting the motion produced upon precession of said gyroscope to said movable mirror.

7. A gunsight trainer, comprising, an optical gunsight having a sighting window through which the reticle image derived therein can be seen, and an arrangement fixed to said gunsight for providing an imitation target image and for causing said imitation target to move relative to and independently of said gunsight, said atrangement comprising a housing mounted upon said gunsight and having a viewing window which is aligned with said gunsight-sighting window through which said gunsight reticle image can be observed, a movable, semi-transmissive mirror suspended within said housing in the line of sight between said viewing and sighting windows, an imitation target image source, means for imposing said target image on said semi-transmissive mirror, means for moving said mirror relative to and independently of said gunsight and housing including a gyroscope having an outer gimbal frame and an inner gimbal frame, said outer gimbal frame being rotatably supported by said housing and free to rotate in a horizontal plane, a shaft mounted on said inner gimbal frame and aligned with the rotor axis of said gyroscope, a torque applying means rotatably mounted on said shaft, means for rotating said torque applying means about said shaft. means for transmitting the motion produced by precession of said gyroscope to said movable mirror, and a pendulum assembly suspended from the inner gimbal frame of said gyroscope.

8. A gunsiizht trainer, comprising, an optical gunsight having a sighting window through which the reticle image derived therein can be seen, and an arrangement fixed to said gunsiqht for providing an imitation target image and for causing said imitation target to move relative to and independently of said gunsight, said arrangement comprising a housing mounted upon said gunsiuht and having a viewing window which is aligned with said gunfight-sighting window and through which said gunsiaht reticle image can be observed, a movable, semitransmissive mirror suspended Within said housing in the line of sight between said viewing and sighting windows, an imitation target image source, means for imposing said target image on said semi-transmissive mirror, means for moving said mirror relative to and independently of said gunsight and housing including a gyroscope having an outer gimbal frame and an inner imbal frame, said outer gimbal frame being rotatablv supported by said housing so as to rotate freely in a h rizontal plane, a shaft aligned with the rotor axis of said gyroscope and mounted on said inner gimbal frame, an air jet rotatably mounted on said shaft, and a svnchro motor having its stator mounted on said shaft and its rotor fixed to said r tatable air jet for controlling the direction in which said air jet reacts.

9. A target simulator for attachment to an optical gn sight to provide a moving target in the field of vi 1 of said optical gunsight, comprising, a housing, a target image source supported by said housing, a gyroscope having a rotor, an outer gimbal frame and an inn r gimbal frame rotatably sup orted bv said outer gimbal frame, said outer gimbal frame be ng rotatably supported by said housing, a semi-transmissive mirror up n which is imposed the target image derived fr m said target image source, said mirror being pivotally mounted on said outer gimbal frame and in the field of vie of said gunsight, a shaft aligned with the rotor axis of said gyroscope and sup orted by said inner imbal frame. air jet means rotatably mounted n. sa d sh ft for ap lying a tor ue perpendicular to said shaft, and a synchro motor having its stat r fixed to the shaft its rotor fixed to said rotatable air jet means for rotating said air jet means about said shaft, thereby causing said gyroscope to precess and said image to move relative to and independently of said gunsight.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,096,254 Lang May 12, 1914 2,269,410 New Jan. 6, 1942 2,293,707 Braddon Aug. 25, 1942 2,313,480 Reid Mar. 9, 1943 2412.453 Grimshaw Dec. 10, 1946 2,420,633 Wittel et al. May 13, 1947 2,424,088 Furman et al. July 15, 1947 2,432,613 Tedde Dec. 16, 1947 2,442.240 Hooker et al. May 25, 1948 2,442,748 Blood et al June 8, 1948 2,471,368 Ekstrom et a1 May 24, 1949 2,473,524 Hubbard et al. June 21, 1949 2,502,834 Dreyer Apr. 4, 1950