US3913870A

US3913870A - Stable gyro reference for projectiles

Info

Publication number: US3913870A
Application number: US322803A
Authority: US
Inventors: R Glenn Bolick
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1973-01-05
Filing date: 1973-01-05
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

A stable gyro reference for enabling flight corrections to spinstabilized projectile trajectories. A drive plate on the projectile body engages and supports the gyro during launch to transfer projectile spin to the gyro. After launch, the gyro separates from the drive plate permitting it to spin freely. Because of the mechanical support given by the drive plate to the gyro during the high acceleration launch, various conventional gyros are suitable for use. Control of range and dispersion errors can be effected through the use of such a gyro system in conjunction with suitable aerodynamic or thruster methods.

Description

United States Patent 1191 Bolick Oct. 21, 1975 [54] STABLE GYRO REFERENCE FOR 2,386,686 10/1945 l-lunsdorf 244 123 PROJECTILES 2,402,718 6/1946 Albree 244/3.l 3,304,029 2/1967 Ludtke 244/32 [75] Inventor: R. Glenn BOllCk, Fred'encksburg,

Primary Examiner-Stephen C. Bentley [73] Assignee: The United States of America as A istant Ex minerC. T. Jordan represented by the Secretary of the Navy, Washington, ABSTRACT [22] Filed: 1973 A stable gyro reference for enabling flight corrections [21] AppL NOJ 322,803 to spin-stabilized projectile trajectories. A drive plate on the projectile body engages and supports the gyro during launch to transfer projectile spin to the gyro. U-Sn CL 3 After launch the gyro eparates from the drive plate [51] Int. Cl. F42B 15/14 permitting it to Spin f l Because f the mechanical Fleld of Search support given the drive plate to the gyro during the 5 R, 541; loz/DIG- 3 high acceleration launch, various conventional gyros are suitable for use. Control of range and dispersion References Clted errors can be effected through the use of such a gyro UNITED STATES PATENTS system in conjunction with suitable aerodynamic or 1,181,136 5/1916 Hayden 244/31 thruster methodsl,3l6,363 9/1919 Hayden 244/3.l 1,459,198 6/1923 Dunajeff 244/3.1 8 1 D'awmg F'gure z/ 1 I9 Ill I6 H l9 A; II

i 11 22 GUIDANCE B A CONTROL 7 POWER SYSTEM I SOURCE STABLE GYRO REFERENCE FOR PROJECTILES BACKGROUND OF THE INVENTION 1. Field of Invention This invention relates generally to gyroscopic space sensing and more particularly to a gyroscope arrangement which will provide a stable reference for spinstabilized projectiles. Various techniques have been evolved in the past to provide control of spinning projectiles during flight. For example, canards or fins mounted on a despun section of the projectile can provide aerodynamic surfaces which control the flight path of the projectile in response to commands from a guidance system. Also, virtually straight-lined trajectories have been obtained by selectively detonating small charges located circumferentially on the base in response to command signals. Additionally, gas ejection has been utilized to produce control forces on bodies of revolution in flight.

2. Description of the Prior Art All of the foregoing techniques have been used successfully in the past. Each requires a reference or datum by means of which the actual trajectories canbe compared to the desired trajectory. Such references have usually taken the form of gyroscopes. These gyroscopes have customarily been provided with their own drive to spin up the gyroscope and have also required extremely rugged construction in order to withstand the high g loads imposed during gun launch. U.S. Pat. No. 3,304,029 discloses such a gyro arrangement in a guided missile. US. Pat. No. 3,369,772 illustrates such complex gyro arrangements in a spin-stabilized rocket.

SUMMARY OF THE INVENTION The present invention obviates the aforementioned problems by holding the gyro in contact with the drive plate on the projectile body during launch to transfer the projectile spin to the gyro and spin up the gyro. The setback forces and release devices hold the gyro against the drive plate during launch. This mechanical support eliminates the need for ruggedized bearings and since during part of the time period of interest the projectile body is rotating with almost the same radial velocity as the gyro, the bearings are less critical than on fixed systems. The gyro is held against the drive plate by a suitable releasable coupling and this means that no orientation of the gyro is required since it is automatic with the axis of rotation being always aligned with the gun tube at launch.

STATEMENT OF THE OBJECTS OF INVENTION It is a primary object of this invention to provide a new and improved stable gyro reference for spinstabilized projectiles.

It is another object of this invention to provide a gyro reference for projectiles wherein projectile spin is utilized to spin up the gyro and obviate the need for a separate gyro drive.

It is a further object of this invention to provide a stable gyro reference for gun launched projectiles wherein the gyro is mechanically supported during the gun launch and thus the need for massive gyro components is precluded.

It is yet another object of this invention to provide a gyro reference which possesses indefinite shelf life because no power unit is required for spin up.

It is a still further object to this invention to provide a stable gyro reference for spin-stabilized projectiles in which the gyro spin axis will be automatically aligned with the gun tube at launch.

BRIEF DESCRIPTION OF THE DRAWING Other objects, advantages and novel features of the invention will become apparent upon consideration of the following detailed description of the invention when considered in conjunction with the accompanying drawing wherein the single FIGURE of the drawing illustrates a full section through a fragment of a projectile body and showing the various components of applicants invention in their storage or pre-launch positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there can be seen a projectile body 10 provided with an interior spherical cavity 11. A spherical gyro 12 is disposed within the cavity 11. A pair of pins 13 are disposed in aligned apertures in the projectile body 10 and gyro 12 and serve to hold the gyro firmly against a drive plate 14 which is formed of a high friction composite material. This is the normal storage position of the gyro 12 with its transverse axis represented by the line 15.

A plurality of bearings 16 are arranged about the surface of the cavity 11 for supporting the gyro 12 when it is rotating. The bearings 16 may be hot or cold gas, electromagnetic, electrostatic, or any other type of non-friction gyro bearings. A bearing power source 18 of the appropriate type is provided for energizing or powering the bearings 16.

A plurality of sensors 19 are disposed on the surface of the cavity 11 and are used to provide flight position data by detecting the relative orientation of the projectile body 10 and gyro 12 during operation. The output of the sensors 19 is fed into a guidance control system 20 to enable flight corrections when necessary. The guidance control system 20 may be any of the systems described above in the background of the invention or may be any other type suitable for guiding spinstabilized projectiles during flight.

OPERATION In order that better understanding of the invention might be had, its mode of operation will now be described. The projectile 10 is loaded into a gun barrel (not shown) with the gyro 12 in contact with the drive plate 14 and the pins 13 in the positions shown in the drawing. When the propulsive charge (not shown) is fired, the projectile 10 rapidly accelerates (accelerations of 10,000 gs are not uncommon) down the gun barrel, and begins to spin rapidly about the spin axis 21 due to the rifling in the gun barrel. The high setback forces hold the gyro 12 firmly against drive plate 14 and thus the spin of the projectile (normally about 300 RPS) is imparted to the gyro which likewise spins around the axis 21. While the projectile body 10 is being spun up, the pins 13 are retracted'by centrifugal force from the gyro 12 into the apertures in the projectile body 10.

When the projectile exits from the gun barrel, the projectile body 10 is no longer accelerating and the bearings 16 then function to shift the gyro along its spin axis until the transverse axis 15 of the gyro coincides with the transverse axis 22 of the cavity 11. The gyro 12 is now freely spinning with its spin axis oriented with the longitudinal axis of the gun barrel. During flight, the relative orientation of the projectile body and gyro 12 is continuously monitored by the sensors 19 and the guidance control system 20. These changes in relative orientation may be due either to the normal ballistic trajectory of the projectile 10 or they may be perturbations due to outside sources. The guidance control system 20 will function to correct the path of the projectile 10 whenever it tends to deviate from the desired trajectory.

It should be appreciated that the invention may be practiced other than as specifically described. For example, the drive plate 14 could be replaced by a serrated surface or other releasable mechanical connection between the projectile body 10 and gyro 12. Also, the setback force alone could be relied upon to maintain sufficient frictional contact between the projectile and gyro to insure spin up of the gyro. Although the gyro 12 has been shown as spherical in configuration, it should be appreciated that conventional gyros of disc configuration would be suitable for use with short range projectiles where the firing trajectory were relatively flat. And further, the pins 13 could be replaced by shear pins or any other releasable device which would serve to retain the gyro in contact with the drive plate during the storage and handling and yet release it subsequent to launch. Obviously, many modifications and variations of the present invention are possible in the light of the above teachings.

What is claimed is:

l. A stable gyro reference for spin-stabilized projectiles comprising:

a projectile body; I

a gyro disposed within a cavity in said projectile body;

means for releasably coupling said gyro to said pro jectile body during launch whereby the stabilizing spin of the projectile will be imparted to said gyro, said coupling means allowing said gyro to spin freely following launch;

bearing means on said projectile body for supporting said gyro following release; and

means responsive to the relative orientation of said projectile body and said gyro for generating error signals to enable correction of the trajectory when necessary.

2. The gyro of claim 1 wherein said coupling means comprises pins disposed in mating apertures of said projectile body and said gyro and retractable into said projectile body by centrifugal force during spin up to release said gyro.

3. The gyro of claim 2 wherein said coupling means includes a drive plate on said projectile body and engaging said gyro during launch to spin up said gyro.

4. The gyro of claim 3 wherein said drive plate is formed of high friction composite material.

5. The gyro of claim 3 wherein said drive plate is serrated and engages corresponding serrations on said gyro.

6. The gyro of claim 1 wherein said bearing means comprise gas bearings.

7. The gyro of claim 1 wherein said bearing means comprise electromagnetic bearings.

8. The gyro of claim 1 wherein said bearing means comprise electrostatic bearings.

Claims

1. A stable gyro reference for spin-stabilized projectiles comprising: a projectile body; a gyro disposed within a cavity in said projectile body; means for releasably coupling said gyro to said projectile body during launch whereby the stabilizing spin of the projectile will be imparted to said gyro, said coupling means allowing said gyro to spin freely following launch; bearing means on said projectile body for supporting said gyro following release; and means responsive to the relative orientation of said projectile body and said gyro for generating error signals to enable correction of the trajectory when necessary.

6. The gyro of claim 1 wherein said bearing means comprise gas bearings.