US3479032A

US3479032A - Gunnery practice scoring apparatus

Info

Publication number: US3479032A
Application number: US557481A
Authority: US
Inventors: John Alex Ingvar Ohlund; Torsten Wilhelm Andersson
Original assignee: Saab AB
Current assignee: Saab AB
Priority date: 1965-06-17
Filing date: 1966-06-14
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18
Also published as: CH448811A; AT261453B; BE682693A; NO117285B; GB1090508A; NL6607828A; SE306483B

Description

1969 J. A. OHLUND ETAL 3,

GUNNERY PRACTICE SCORING APPARATUS Filed June 14, 19 66 4 Sheets-Sheet 1 JalzzzA/mfzy wrfil'zlund 221mm mlbelmAniprsian & m ME Nov. 18, 1969 J, A. 1. OHLUND ETAL 3,

GUNNERY PHACTICE SCORING APPARATUS 4 Sheets-Sheet 5 Filed June 14, 1966 Tarszm M/MzzzAndiriiz n N v- 8, 1969 J, A. LOHLUND ETAL. 3,

GUNNERY PRACTICE SCORING APPARATUS Filed June 14, 1966 4 Sheets-Sheet. 4

United States Patent 3,479,032 GUNNERY PRACTICE SCORING APPARATUS John Alex Ingvar Ohlund, Huskvarna, and Torsten Wilhelm Andersson, Jonkoping, Sweden, assignors to Saab Aktieholag, Linkoping, Sweden, a corporation of Sweden Filed June 14, 1966, Ser. No. 557,481 Claims priority, application Sweden, June 17, 1965, 8,005/ 65 Int. Cl. A63b 69/00, 63/00 US. Cl. 273102.2 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to signaling devices for scoring gunnery target practice, and pertains more particularly to means for producing an electrical signal in response to a hit upon a target plate, whereby indications of the results of firing at the target plate can be made available at location remote therefrom.

In a general way the present invention relates to the class of signaling devices for scoring gunnery target practice that is disclosed in Patent No. 3,158,372, to I. A. I. Ohlund et al. issued Nov. 24, 1964, comprising a target plate that defines an area in which shots are to be placed and a transducer arranged to cooperate with the target plate in producing an electrical signal in response to each hit on the target plate.

In the device of that patent the target plate was of substantially rigid vibration transmitting material, and the transducer, which was highly directional, was directly secured to an edge portion of the target plate with its axis of sensitivity substantially in the plane of the target plate. A projectile striking and penetrating the target plate forced the plate material edgewise outwardly, thus propagating through the target plate an edgewise traveling shock wave that vibrated the transducer along its axis of sensitivity and thereby caused it to produce an electrical signal.

Owing to the directional character of the transducer and the manner of its connection to the target plate, the signaling device of that patent was substantially nonresponsive to near misses and other disturbances which vibrated the target plate in directions other than edgewise. However the direct attachment of the transducer to the target plate also exposed the transducer to all fire directed towards the target plate, and the transducer was therefore likely to be struck by a projectile and destroyed at any time during the course of a target firing session. Suchdestruction of the transducer was both inconvenient and costly, because it made necessary an interruption of the target firing session and replacement of the ruined transducer.

By contrast, it is a principal object of the present invention to provide target practice signaling apparatus of the character above described, comprising a target plate of substantially rigid vibration transmitting material and a highly directional transducer, which apparatus is substantially nonresponsive to disturbances other than the striking of the target plate by a projectile, and features location of the transducer at a distance from the target plate so that the transducer can be disposed in a sheltered zone where it is not subject to the impact of projectiles or of stones and the like that are thrown up from the ground by projectiles striking near the target plate.

Another object of this invention is to provide a gunnery target practice hit signaling device of the type comprising a substantially rigid target plate and a highly directional transducer, wherein the transducer is mounted at a distance from the target plate, and can be so located as to be protected from the effects of firing at the target plate, and wherein there is a vibration transmitting connection between the target plate and the transducer which is of such character that the transducer produces signals substantially only in response to actual hits upon the target plate.

It is also an object of this invention to provide a novel highly directional transducer for producing an electrical signal in response to high but brief acceleration of the transducer along its axis of sensitivity, such as occurs when the transducer is subjected to a shock wave produced by a projectile striking a substantially rigid target plate with which the transducer is mechanically connected.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiments of the herein disclosed invention may be made as come within the scope of the claims.

The accompany drawings illustrate several complete examples of physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a rear perspective view of :an array of fixedly supported target plates, each of which is provided with a signaling device embodying the principles of this invention;

FIGURE 2 is a fragmentary longitudinal sectional view through a bottom portion of one of the target plates shown in FIGURE 1 and through its associated transducer, particularly showing the connection between the target plate and the transducer;

FIGURE 3 is a longitudinal sectional view of a modified form of connection between the target plate and the transducer;

FIGURE 4 is a longitudinal sectional view on a larger scale of the transducer;

FIGURE 5 is a rear perspective view of another form of target equipped with modified signaling apparatus of this invention;

' FIGURE 6 is a view generally similar to FIGURE 3 but illustrating details of the connection between the target plate and the transducer of the apparatus shown in FIGURE 5;

FIGURE 7 is a rear perspective view of another modified form of the invention, comprising a tiltable target plate;

FIGURE 8 is a view generally similar to FIGURE 2 but illustrating another modified embodiment of the invention; and

FIGURE 9 is a longitudinal sectional view of the transducer of the embodiment of the invention illustrated in FIGURE 8.

Referring now to the accompanying drawings, FIG- URES 1 and 2 illustrate gunnery target practice apparatus embodying the principles of this invention and comprising an array of upright target plates 5 mounted in substantially coplanar side-by-side relationship, each associated with a transducer 6 which produces an electrical signal when a hit is scored on the target plate. The several transducers 6 are electrically connected, by suitable conductor means 7, with a recording device 8 of known type. The recording device 8, which may be located remotely from the array of target plates 5, produces readily observable indications of the results of firing at the target plates.

The target plates are rigidly connected along their adjacent side edges to posts or standards 9 which support them. The lower ends of the posts 9 are fixed to the ground by any suitable means, and are preferably located in a pit 10 above which the target plates project and in which the transducers 6 are disposed directly beneath their respective target plates, so that the transducers are thereby protected from the effects of weapons fire directed at the target plates.

Each of the target plates comprises a sheet of a substantially rigid vibration transmitting material, such as hardboard of the type available under the trademark Masonite. As mentioned hereinabove, when such material is struck by a projectile there is a displacement of the plate material in directions edgewise of the plate, by which an edgewise traveling shock wave is propagated through the plate. Each of the transducers 6 has a vibration transmitting connection with its target plate whereby the shock wave produced by a projectile hitting the plate is imposed upon the transducer to cause it to emit an electrical signal. Such connection comprises an elongated, substantially rigid vibration transmitting member 11, a U-shaped connecting member 12 by which one end of the vibration transmitting member is maintained firmly connected with an edge of the target plate, and means providing a rigid connection between the other end of the connecting member and the transducer.

The vibration transmitting member 11, which can comprise a metal rod, must be capable of transmitting vilbrations along its length, and the transducer must have its directional axis substantially in the plane of the target plate and substantially coinciding with the axis of its adjacent end portion of the vibration transmitting member. Under these conditions the transducer will respond to edgewise traveling shock waves in the target plate but wil be substantially nonresponsive to other oscillations and vibrations of the target plate.

The U-shaped connecting member 12, by which a vibration transmitting connection is maintained between the rod 11 and the target plate, straddles the lower marginal edge portion of the target plate with its

legs

14 and 15 overlying the opposite faces thereof. A set screw 16 through the leg 14 of the U-shaped member engages its adjacent face of the target plate to clampingly secure the U-shaped member thereto.

In the embodiment of the invention illustrated in FIG- URE 2 the vibration transmitting member or rod 11 6X- tends through a loosely fitting hole 17 in the bight portion of the U-shaped member, between and parallel to the

legs

14 and 15 thereof. A coiled expansion spring 18 surrounding the upper end portion of the rod 11 reacts between the bight portion of the U-shaped member and a nut 19 threaded onto the tip portion of the rod to bias the rod upwardly toward firm endwise abutting engagement with the lower edge of the target plate. The nut 19 can be adjusted axially along the upper portion of the rod to vary the load on the spring 18 and thereby adjust the force under which the rod engages the edge of the target plate. To insure good transmission of vibrations, a small load distributing plate 21 can be confined between the lower edge of the target plate and the top of the rod.

Washers

22 and 23 carry the reaction forces of the spring 18 into the nut 19 and the bight portion of the U-shaped member, respectively.

It will be observed that this spring biased connection between the target plate and the rod 11 minimizes the transmission to the rod of vibrations of the target plate in directions other than edgewise.

In the embodiment of the invention illustrated in FIG- URE 3 the upper end portion of the vibration transmitting rod 111 is threaded through the bight portion of the U-shaped connecting member 112 so that the rod can be screwed through the U-shaped member to an axial position in which the top of the rod has firm engagement with the lower edge of the target plate. A transverse pin 24 through the rod 111 facilitates turning the rod for the purpose of adjusting it to such position. In this embodiment, too, a load distributing plate 21 is preferably confined between the top of the rod 111 and the bottom edge of the target plate. A pad 25 of resilient vibration damping material is confined between the leg 15 of the U- shaped member and its adjacent surface of the target plate to minimize the transmission of flatwise oscillations.

of the target plate to the vibration transmitting rod.

The directional transducer 6, as illustrated in FIGURE 4, comprises a rigid closed housing 26 of insulating material which can be generally drum shaped, but with a coaxial nipple 27 on its top into which the lower end of the vibration transmitting rod 11 projects. A transverse pin 2-8 extends through the nipple and the rod to provide a rigid vibration transmitting connection between them which insures that the housing 26 partakes of axial vibrations of the rod. Secured to and extending through the side wall of the housing 26 are a pair of spring metal strips 30 and 31, which have at their inner ends relatively fixed and

movable contact members

32 and 33 that are normally in circuit making engagement with one another. The projecting outer end portions of the spring strips 30 and 31 provide terminals 34 that are connectable with the conductors 7 by which the

contact members

32 and 33 are connected in series circuit with a suitable current source and with the recording device 8. The inwardly projecting arm 35 of the spring strip 30, which carries the relatively fixed contact member 32, is fairly short and therefore comparatively rigid, while the inwardly projecting arm 36 of the spring strip 31, which carries the movable contact member 33, is relatively long and resilient and has a mass load 37 near its free end so as to be inertia responsive. The

arms

35 and 36 project substantially radially into the housing from opposite sides thereof, with the longer arm 36 disposed above the shorter arm 35.

The

contact members

32 and 33 are normally held engaged under a biasing force which can be adjustably varied by means of a set screw 38 threaded up through the bottom of the housing and acting upon the shorter arm 35 to force it upwardly to a greater or lesser extent and thereby vary the flexing load on the longer arm 36. However, a shock wave transmitted to the housing through the rod 11, by which the housing is abruptly accelerated downwardly, flexes the longer arm 36 upwardly under the inertia of the mass load 37, thereby momentarily separating the

contact members

32 and 33 and opening the electrical circuit through them.

Since the spring arm 36 is disposed with its surfaces normal to the housing axis, vibrations and oscillations of the transducer in directions transverse to its axis do not cause separation of the contact members. The transducer housing can be filled with oil to damp motion of the spring arm 36.

To protect the transducer from. air pressure shock waves due to passing projectiles and from other vibrations such as those arising from stones thrown up against it, it is embedded in a body of spongy material 40 that is enclosed in a metal shell 41, and the shell is in turn enclosed in a cage 42 of rubber or similar elastic material that protects it from damage. The conductors 7 pass through a resilient nipple or grommet 43 in the shell.

In the embodiment of the invention illustrated in FIG-

URES

5 and 6, the target plate 5 is suspended from a rigid frame 9' by means of elastic supporting strips 45 of a material such as rubber cloth, so that the target plate is insulated from vibrations of the frame. As in the previously described embodiment of the invention, the transducer 6 is located in a protected position, in a pit 10 beneath the target plate, and a rod-like vibration transmitting member 211 connects the target plate with the transducer. The medial portion of the vibration transmitting rod 211 is formed as a helical spring, as at 46, so as to be substantially incapable of transmitting vibrations and oscillations in directions perpendicular to its axis, such as oscillations of the target plate in directions normal to the plane thereof.

' In the FIGURES and 6 embodiment of the invention the vibration transmitting rod has its upper and immovably anchored to the U-shaped connecting member 212 that straddles a lower marginal edge portion of the target plate, and the set screw 16 by which the U-shaped member is secured to the target plate is inclined downwardly and inwardly and engages an obliquely upwardly facing bevel 48 on the target plate, so that tightening the screw 16 tends to force the bight portion of the U-shaped member upwardly toward snug engagement with the edge of the target plate. Again, a load distributing plate 21 is interposed between the edge of the target plate and the bight portion of the U-shaped member to promote transmission to the vibration transmitting rod of edgewise traveling shock waves in the target plate; and a pad 25 of vibration damping material is interposed between the leg 15 of the U-shaped member and its adjacent surface of the target plate. The transducer 6 and its connections with other elements of the apparatus can be the same as in the previously described embodiments of the invention.

In the embodiment of the invention illustrated in FIG- URE 7 the target plate 5 is mounted between frame members 49 which are pivoted on

coaxial trunnions

50 and 50 carried on short upright posts 9" so that the target plate can be swung between a substantially horizontal inoperative position, in which it is practically invisible, and an upright operative position in which it is shown. An arm 51 on one of the frame members, projecting beyond the axis of the trunnions, is connected with a double acting hydraulic or pneumatic cylinder 52 by which the target plate can be tilted to and from its operative position.

In this instance the transducer 6 is mounted on an inward extension 53 of the trunnion 50, with its axis coinciding with that about which the target plate tilts. The vibration transmitting rod 311 is L-shaped, and has its upper end connected with the lower marginal edge portion of the target plate, as by means of any of the above described U-shaped connectors, while its lower portion extends horizontally along the tilting axis of the target plate and is connected with the transducer 6 in the manner previously described. The conductors 7 that are connected with the transducer are brought out of the shell around the transducer on its axis, the trunnion 50" upon which the transducer is mounted being tubular so that the conductors can extend through it.

In the embodiment of the invention illustrated in FIGURES 8 and 9, which features a modified embodiment of the transducer, the connection between the target plate 5 and the vibration transmitting rod 11 is the same as in the embodiment of the invention illustrated in FIGURE 2, but the vibration transmitting rod 11 must be formed of electrically conductive material inasmuch as its lower end comprises the fixed contact member 32 of the transducer 6. The tranducer housing 26' is a sleeve of insulating material that is firmly secured to the lower end portion of the rod 11 in telescoped relation thereto, preferably by being threaded onto the rod. The lower end of the sleeve 26' is closed by an electricaly conductive set screw 38' threaded upwardly thereinto and p a washer 34 confined between a pair of locking nuts 55 on the set screw 38. The locking nuts of course maintain the set screw in any axial position to which it may be adjusted. Such adjustment of the set screw, by regulating the preload on the spring 36', controls the sensitivity of the transducer.

It will be apparent that upward axial acceleration of the lower end of the rod 11 causes inertia produced relative movement of the ball 37' downwardly out of engagement with the bottom of the rod, breaking the electrical connection between the conductors 7 that normally exist through the bottom of the rod 11, the ball 37, the spring 36' and the set screw 38'.

From the foregoing description taken together .with the accompanying drawings it will be apparent that this invention provides very reliable signaling apparatus for scoring gunnery target practice, which apparatus is responsive to direct hits scored upon the target but is substantially nonresponsive to other distrurbances; and it will also be apparent that in the apparatus of this invention the sensitive and relatively expensive transducer, which produces an electrical signal in response to a shock wave due to a hit on the target, can be located at a distance from the target and in a protected location where it is safe from projectiles fired at the target.

What is claimed as our invention is:

1. A signaling device for scoring gunnery target practice comprising:

(A) a target plate of substantially rigid vibration transmitting material defining an area in which shots are to be placed;

(B) a substantially rigid transducer housing;

(C) an elongated member capable of transmitting vibrations in its lengthwise direction, said member having vibration transmitting connections at its opposite ends with the target plate and with the transducer housing, respectively, and having its axis substantially in the plane of the target plate surface so as to transmit to the housing edgewise traveling shock waves in the target plate;

(D) a first contact member fixed in the housing and connectable with an electrical conductor;

(E) a second contact member in the housing, movable toward and from engagement with the first contact member in directions substantially parallel to the length of the elongated member, said second contact member having substantial mass and being connectable with an electrical conductor; and

(F) biasing means reacting between the housing and the second contact member to urge the latter in the direction toward the first contact member, said biasing means being yieldable to permit inertia produced separation of the contacts in consequence of abrupt motion of the housing in the opposite direc tion.

2. The transducer of claim 1 further charatcerized by:

a covering of soft vibration absorbing material around said housing for substantially preventing the transducer from being affected by shock and vibration forces other than shock waves traveling edgewise through the target plate.

3. In a signalling device for scoring gunnery target practice, of the type comprising a target plate of substantially rigid vibration transmitting material defining an area in which shots are to be placed, and a shock Wave responsive transducer for producing an electrical signal in response to a shock wave traveling through the target plate as the result of a projectile hitting the same:

(A) means for mounting the transducer in a protected location spaced edgewise from the target plate and near the plane thereof with the axis of sensitivity of the transducer substantially parallel to the plane of the target plate surface;

(B) an elongated member capable of transmitting vibrations in its lengthwise direction;

(C) means providing a first vibration transmitting connection between one end of the elongated member and an edge portion of the target plate, said last named means comprising (1) a substantially U-shaped member having legs overlying opposite marginal edge surface portions of the target plate and clampingly engaging the same, and

(2) cooperating means on said U-shaped member and said end portion of the elongated member by which the latter is forced axially toward said edge portion of the target plate and is held with its axis substantially in the plane of the target plate; and

(D) means providing a second vibration transmitting connection between the transducer and the other end of the elongated member, whereby the elongated member transmits to the transducer shock waves traveling edgewise through the target plate.

4. The signaling device of claim 3, further characterized by:

(A) the elongated member comprising a rod having its said one end portion extending through the bight portion of the U-shaped member; and

(B) spring means reacting between the U-shaped member and the elongated member to maintain biasing force upon said one end portion of the elongated member urging it axially toward said edge portion of the target plate.

5. The signaling device of claim 3, further characterized by:

said cooperating means on the U-shaped member and on the elongated member comprising a screw threaded connection between them.

6. The signaling device of claim 3, further characterized by:

(A) resilient means confined between one of said legs of the U-shaped member and its adjacent surface of the target plate for minimizing transfer to the elongated member of vibrations of the target plate in directions other than edgewise; and

(B) securement means on the other leg of the U- shaped member clampingly engaged with its adjacent surface of the target plate to secure the U- shaped member thereto.

7. In a signaling device for scoring gunnery target practice, of the type comprising a target plate of substantially rigid vibration transmitting material defining an area in which shots are to be placed, and a shock wave responsive transducer for producing an electrical signal in response to a shock wave traveling edgewise through the targetplate in consequence of a hit upon the same by a projectile:

(A) means mounting the tranducer in a protected location spaced edgewise from the target plate and near the plane thereof and with the axis of sensitivity of the transducer substantially parallel to the plane of the target plate surface; and

(B) means providing -a vibration transmitting connection between the target plate and the transducer by which the force of an edgewise traveling shock wave in the target plate is imposed upon the transducer, said means comprising an elongated member which is substantially rigid along its length to be capable of transmitting vibrations in its lengthwise direction said elongated member (1) having one end rigidly connected with the tranducer,

(2) having its other end firmly connected under axial biasing force with an edge portion of the target plate by means yieldable in directions transverse to the length of the elongated member so that the transducer is substantially unaflected by vibrations of the target plate in directions other than edgewise, and

(3) having its axis substantially in the plane of the target plate.

References Cited UNITED STATES PATENTS 3,097,848 7/1963 Massa 273-l 02.2

3,158,372 11/1964 Ohlund et a1 273l02.2

FOREIGN PATENTS 1,009,068 5/ 1957 Germany.

ANTON -O. OECHSL'E, Primary Examiner M. R. PAGE, Assistant Examiner