US3900198A

US3900198A - Expendable self-powered target with stabilizing control

Info

Publication number: US3900198A
Application number: US379415A
Authority: US
Inventors: Jack S Conner
Original assignee: Northrop Grumman Corp
Current assignee: Northrop Grumman Systems Corp
Priority date: 1973-07-16
Filing date: 1973-07-16
Publication date: 1975-08-19
Anticipated expiration: 1992-08-19

Abstract

A radar-augmented target pod to be launched from a drone aircraft and act as a flying target for weapon system crew training. The launching drone is recoverable for re-use, while the target pod is extremely simple and expendable after its one flight. It is powered by a JATO rocket unit for example, and has a simple air-driven direction-holding mechanism and an automatic weight shifting design to maintain substantially constant altitude until power burnout.

Description

United States Patent Conner Aug. 19, 1975 [54] EXPENDABLE SELF-POWERED TARGET 2,960,035 11/1960 Burton 244/3.21

WlTH STABILIZING CONTROL i333 L P 333%: s aml 011.. [75] Inventor: J k 8- nn r, p g Calif. 3,563,501 2 1971 Jensen 244/79 Assignee: Northrop Corporation, Los g y 3,735,985 5/1973 Layer 244/3.24

a 1 Primary Examiner-Richard C. Pinkham [22] Filed: July 16, 1973 Assistant Examiner-Marvin Siskind Attorney, Agent, or FirmWilliam W. Rundle' Willard 21 A l. N 379,415 I 1 pp 0 M. Graham [52] US. Cl. 273/1054; 244/79; [57] ABSTRACT 51 1 Int Cl F4 9/08 A radar-augmented target pod to be launched from a [58] Field of Search 244/3.24, 79, 3.16, 3.21; drone aircraft f f act as a flying target for weapon 273/1053 105% l 14/122 102/341 system crew training. The launching drone 1S recoverable for re-use, while the target pod is extremely sim- [56] References Cited ple and expendable after its one flight. It is powered I by a JATO rocket unit for example, and has a simple UNITED STATES PATENTS air-driven direction-holding mechanism and an auto- Miners matic design to maintain substantially 3 constant altitude until power burnout.

-. opper... 2,957,417 10/1960 Musgrave 244/3. 16 6 Claims, 4 Drawing Figures PATENTE Ans-1 9197s 3,900,198 sum 1 [IF 2 PATENTEU AUGI 9191s SWEET 2 OF EXPENDABLE SELF-POWERED TARGET WITH STABILIZING CONTROL The present invention relates to aerial targets, and more particularly, to a cheap expendable target to be launched from a carrier aircraft, which target has automatic flight control and suitable characteristics for a weapon aimed at it for test purposes.

It is known to launch radio-controlled drone targets from the ground or from piloted aircraft for gun or missile testing and gun crew training, these drones being parachute-recovered and salvaged for reuse if not destroyed by weapon hits or crash landings. It is also known to tow a flying target from an aircraft at the end of a long tow line while missiles are fired at the target. Both these expedients are wasteful and unsuitable in several respects. Recovery, rebuilding and replacement of the drones is expensive, while automatic loss of the towed target and its long tow line is also expensive. Further, in the case of the towed target, an attack angle of the weapon from a head-on direction and up to a certain angle away from head-on is prevented due to the position occupied by the towing craft. These objections have made it desirable to find a better target system, but none has appeared yet.

It is an object of this invention to provide a new target for the function described which is workable and also economically disposable whether intercepted or not.

Other objects and advantages of the present invention will be noted in the detailed description of specific apparatus to follow.

Briefly. my target invention comprises a powered flying body to be launched from a small drone aircraft, the target having a radar reflector or other simple stores, for example, and having heading control and/or constant altitude to weapon intercept. The heading control is a unique air-powered or battery-powered gyro mechanism which uses the direct mechanical output of a spinning gyro to drive a linkage connected to a control surface. To achieve level flight of the target after launching from its carrier drone or aircraft, the longitudinal position of the center of gravity may be purposely varied to move forward accompanying acceleration of the target.

The invention will be more fully understood by reference to the following detailed description of a preferred embodiment illustrated in the accompanying drawings, wherein:

FIG. 1 is a perspective view of a powered pod target embodying the present invention.

FIG. 2 is a plan view of the target of FIG. 1.

FIG. 3 is a left elevation view, partly in section, of the target of FIG. 1, showing internal control apparatus.

FIG. 4 is an isometric diagram illustrating the arrangement of the control gyro in the fuselage.

Referring first to FIG. 1 for a detailed description of the present embodiment, a flying target 1 comprises a body or fuselage-2, wing 4, horizontal tail 5 and vertical tail 6. The vertical tail 6 carries a fore-and-aft hanger slot 7 open at the trailing edge of the tail 6. Above this slot 7, the vertical tail 6 has a substantially cylindrical longitudinal launch support 9. Under the wing of the target carrier aircraft (not shown) a pipe-like member is provided. into which the launch support 9 is loaded. The target 1 is thus carried supported by the tail until the launching moment when the target thrust carries it forward off of the carrier pipe. The carrier aircraft it- As shown in FIG. 3, a J ATO type rocket unit 10 is positioned within the fuselage 2, with its nozzle 11 protruding aft. Conventional ignition wires 12 extend from the rocket unit 10 to the carrier aircraft for ignition and then break-away.

The nose of this target fuselage 2 carries a radar echo augmenting device 14 such as a Luneberg lens for example. Since the present target is to be small and inexpensive, the fuselage 2 may be only about 5 inches in diameter, for example, and the radar reflective device 14 is preferred to be the smallest diameter compatable with range of weapon intercept. The close-in launch requires the smaller lens. In the present illustration, the reflector 14 is slightly larger than the fuselage diameter.

Heading control of the target 1 is provided by a rate gyro-operated mechanism. As shown in FIGS. 3 and 4, a gyro wheel or rotor 15 is mounted with its axis of rotation in a horizontal and lateral direction. The gyro rim carries buckets or impeller blades 16 which extend below the bottom of the fuselage 2 and are driven by the airstream.

Rotor l5 spins about a central rotor bearing 17 on the end of a rigid cantilevered mounting shaft 19 fixed rigidly at its right-hand end, for example, to half gimbal 20 lying normally in a horizontal plane and having two

gimbal bearings

21 and 21a at its pivot ends. These

gimbal bearings

21 and 21a are mounted along a foreand-aft gimbal axis 22 on yoke arms of a bracket member 24 which is fixed solidly to the fuselage structure as by two bolts 25 attaching bracket 24 to a fixed fuselage member 26. Thus in operation, rotor 15 is spinning in a vertical plane. A caging mechanism (not shown) may be provided, and counterweights (not shown) may be provided on half gimbal 20 to the left of the axis 22 to balance the gimbal and shaft assembly.

To the left end of rotor 15, a small diameter, short flexible steel shaft 27 is fixed to the center of rotor 15 to rotate therewith. The purpose of this flexible shaft 27 will be described later.

The bracket 24 also has a bellcrank member 29 pivotally connected thereto at pin 30. Bellcrank 29 has a lower suspended portion 31 in which a curved slot 32 is provided in a fore-and-aft direction, the slot radius being centered at the pivot pin 30. The flexible shaft 27 protrudes through the center of this slot 32, and the slot width is slightly greater than the diameter of flexible shaft 27, so that when centered the shaft 27 will spin freely without contacting either the upper or lower side of the slot 32.-

A short bellcrank arm 34 extends upward from pivot pin and has its end pivotally connected to the forward end of a push-pull rod 35 which extends to the exterior through a fuselage slot. The rear end of rod 35 is pivotallyv connected to an aileron horn 36 extending upward to be operatively connected to an aileron 37 hinged to the rear of the right-hand side of the wing 4. The gyro rotor 15, bellcrank linkage, and left end of the aileron-37 are all preferably located substantially at the fuselage center line plane for simplicity.

In operation, this heading control system automatically keeps the target 1 in a substantially straight flight path. Assume that during its flight, it starts to turn toward the left, for example, thus rotating about the vertical axis. With reference to FIG. 4, this can be seen to cause gyro precession about the gimbal axis 22 in the direction to raise the end of the flexible shaft 27. The bending resistance of shaft 27 is proportional to its deflection. This shaft 27, thus acting as a rate spring, will contact the upper side of curved slot 32, and due to rotor rotation in the direction indicated, the frictional physical reaction between the shaft 27 and slot 32 moves the bellcrank lower portion 31 forward. This moves the bellcrank arm 34 rearward and the bellcrank thus acts as an actuating member to rotate the aileron horn 36 rearward, hence rotating the aileron 37 upward at its trailing edge. This of course rolls the target 1 to the right and thus causes a right turn sufficient to cancel the original left turn and therefore bring the flexible shaft 27 back to the center of groove 32 and remove the aileron correction movement. The short bellcrank arm 34 being closer to the pivot pin 30 than is the slot 32, causes a force multiplication between the frictional force on slot 32 and the force exerted in the push rod 35.

It can be likewise seen that a right turn from straight flight will produce a left bank of the target 1 to again straighten its course.

The flexible shaft 27 is preferably provided with a rough surface such as a coating of diamond grit or the like, to increase its frictional force on the bellcrank slot 32. The gyro rotation speed is restored by the airstream when the flexible shaft 27 is returned to center. It is im portant to note that the kinetic energy of the gyro rotor itself is used to cause the corrective control force, and not just the precession force alone, which is too small to use directly. No electrical power or actuation equipment is required to be carried by the target since the entire work is mechanically transferred from the airstream rotating the gyro. Rotor speed build-up is accomplished prior to launch while being carried under the carrier drone. Of course, the rotor may be driven by a battery-operated motor (not shown), if desired, but for the expendable target purpose involved here, the rotor is required to operate for only about 70 seconds, for example. After release from the carrier drone, the interception of the target lby the missile fired at it occurs considerably prior to the burnout time (70 seconds in this example) of the JATO unit 10.

Level flight of the target 1, within limits, is maintained by utilizing the target center of gravity shift due to propellant burning. ln flight, the target 1 accelerates from launch to burnout. The increased velocity of this simple craft would normally causes simultaneous climb. A forward-burning propellant is used in the rocket unit 10, thus reducing the weight on the rear side of the center of gravity and causing a nose-heavy condition which keeps increasing throughout the powered flight. The climb normally due to acceleration is calculated to be equal and opposite to the reduction in altitude normally due to the nose heavy condition, thus providing a substantially level target flight until burnout.

To enable economy, the fuselage 2 is preferably a simple tube sized to fit closely around a standard JATO unit, say of 5 to 6 inch diameter for example. The horizontal and

vertical tail

5 and 6 can be pressed steel. The gyro is placed in a forward position necessary to keep the major weight components well forward. Also, the gyro is preferably made of as large a rotor diameter as is possible, this being provided by the availability of most of the fuselage height.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise the preferred form of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

What is claimed is:

1. An airborne target comprising a body, a thrust motor in said body, means for launching said target into flight and starting said motor, radar reflecting means in said body, a gyro rotor, means for spinning said rotor, a movable direction control member on said target for controlling the course heading of said target, and means responsive to gyro precession for deflecting said direction control member in a turn-nulling direction, said latter means including a rotor-driven element movable solely and directly by the rotational energy of said rotor, said rotor-driven element being brought into direct physical mechanical contact with a spinning portion of said rotor by precession due to heading change of said target.

2. Apparatus in accordance with claim 1 including a wing on said target body, and wherein said direction control member comprises a single aileron on said wing.

3. Apparatus in accordance with claim 1 wherein said rotor spinning means comprises blades on the periphery of said rotor, said rotor extending partially into the airstream where the airstream spins said rotor by impinging on the blades so exposed.

4. An airborne target comprising:

a. a body having a thrust motor and radar reflecting means in said body;

b. means for launching said target into flight and starting said motor;

c. means in said target for maintaining substantially constant altitude until stoppage of said motor;

d. direction maintaining control means in said target including a gyro rotor and means for spinning said rotor;

e. a movable direction control member on said target;

f. a rigid axle shaft concentric with the spin axis of said gyro rotor, said rotor being cantilevermounted at one end of said rigid shaft;

g. a half gimbal having the other end of said rigid shaft connected to its midpoint, said rigid shaft extending normally laterally of said target, and the ends of said half gimbal located on a fore-and-aft gimbal axis in said target body;

h. a short flexible spring shaft attached to the center of said rotor and rotating therewith on the other side of said rotor from said rigid shaft, said flexible shaft having a roughened surface;

i. a rotor-driven element having a slot fitting over said flexible shaft and normally spaced therefrom, said slot positioned such that precession of said rotor caused by a directional change of said target brings said flexible shaft against one side of said slot in frictional driving relation; and

j. actuating means connected from said rotor-driven element to said direction control member.

5. Apparatus in accordance with claim 4 wherein said actuating means comprises force-multiplying means.

6. Apparatus in accordance with claim 4 wherein said rotor-driven element is pivotally mounted in said target about a pivot point, said slot being arcuate with the center of are at said pivot point, and wherein said actuating means comprises a force-multiplying linkage means.

Claims

1. An airborne target comprising a body, a thrust motor in said body, means for launching said target into flight and starting said motor, radar reflecting means in said body, a gyro rotor, means for spinning said rotor, a movable direction control member on said target for controlling the course heading of said target, and means responsive to gyro precession for deflecting said direction control member in a turn-nulling direction, said latter means including a rotor-driven element movable solely and directly by the rotational energy of said rotor, said rotordriven element being brought into direct physical mechanical contact with a spinning portion of said rotor by precession due to heading change of said target.

4. An airborne target comprising: a. a body having a thrust motor and radar reflecting means in said body; b. means for launching said target into flight and starting said motor; c. means in said target for maintaining substantially constant altitude until stoppage of said motor; d. direction maintaining control means in said target including a gyro rotor and means for spinning said rotor; e. a movable direction control member on said target; f. a rigid axle shaft concentric with the spin axis of said gyro rotor, said rotor being cantilever-mounted at one end of said rigid shaft; g. a half gimbal having the other end of said rigid shaft connected to its mid-point, said rigid shaft extending normally laterally of said target, and the ends of said half gimbal located on a fore-and-aft gimbal axis in said target body; h. a short flexible spring shaft attached to the center of said rotor and rotating therewith on the other side of said rotor from said rigid shaft, said flexible shaft having a roughened surface; i. a rotor-driven element having a slot fitting over said flexible shaft and normally spaced therefrom, said slot positioned such that precession of said rotor caused by a directional change of said target brings said flexible shaft against one side of said slot in frictional driving relation; and j. actuating means connected from said rotor-driven element to said direction control member.

6. Apparatus in accordance with claim 4 wherein said rotor-driven element is pivotally mounted in said target about a pivot point, said slot being arcuate with the center of arc at said pivot point, and wherein said actuating means comprises a force-multiplying linkage means.