US 2887057 A
Description (OCR text may contain errors)
May 19, 1959 v R. H. sEVERANcE 2,887,057
' FUZE ARMING MECHANISM Filed Aug. 1o. 1955 Unite States arent FUzE ARMnvG MECHANISM Ralph' H. Severance, Fort Wayne, Ind., Iassignor to The MagnavoxCompany, Fort Wayne, 1nd., a corporation Application August 10,1955, Serial No. 527,614
1 Claim. (Cl. 102-79) This invention relates generally to fuze arming mechanisms and more particularly it relates to a mechanism responsive to lineal acceleration and angular acceleration for arming fuzes in spin stabilized rockets or other projectiles of like nature.
In connection with rocket projectiles or other types of projectiles, it is conventional to stabilize their flight by the use of ns attached to the rear of the projectile, the ns acting in response to air pressure to keep the projectile on a pre-determined course. Another method of stabilizing all types of projectiles is to cause the projectile to spin duriugits flight. In rockets, a typical method of producing such spinning action is by directing the ilow of exhaust gases at an angle to the line of flight, which causes the rocket to rotate and thereby tend to follow a predetermined course.
Conventional fuze arming mechanisms are arranged to respond to linear acceleration of projectiles or rockets.
vIn the case of rockets having fins, it is necessary to assume that the rockets Will be stabilized by the fins and hence it is safe to arm the rocket only in response to its acceleration whereby a fuze arming mechanism responsive only to linear acceleration may be used with comparative safety, as the rocket will not be armed until it has progressed a predetermined distance along its course.
On the other hand it may be possible that a spinning type of rocket can be launched and for one reason or another it may fail `to spin with sufficient angular velocity to be fully stabilized. If the rocket is not fully lstabilized so that it follows its pre-determined course, lthen it is dangerous to arm the rocket. Accordingly, there is denite advantagein providing a fuze-arming mechanism which will arm the rocket fuze only after the rocket is launched and only after it has accelerated linearly and angularly to a pre-determined degree.
The principal object of this invention is to provide, for
spinning projectiles, a fuze arming mechanism responsive to linear acceleration and angular acceleration for arming the projectile fuze only after the projectile has been accelerated linearly and angularly to a pre-determined degree.
Another object of this invention is to provide a fuze arming mechanism for spinning projectiles of such character that the force generated by linear acceleration of the projectile must attain a certain value, and the force generated by angular acceleration of the projectile must attain a certain value before the arming mechanism can operate to arm the projectile.
In accordance with this invention there is provided a fuze arming mechanism comprising a mass adapted to be mounted within a spinning type of projectile in such a way that it may move in response to a pre-determined degree of linear acceleration and in response to a predetermined degree of angular acceleration into an arming position.
The full nature of the invention will be understood from the accompanying drawings and the following description and claim:
Fig. 1 is a longitudinal cross-section of a projectile embodying the fuze arming mechanism as provided in accordance with the invention.
Fig. 2 is a graph showing the relationship between linear acceleration of a projectile and distance of ight of such a projectile.
Fig. 3 is a graph illustrating the relation between angular velocity of a projectile and linear distance of Hight of that projectile. v
Fig. 4 is a graph illustrating the relation of centrifugal force, existing on a body within the projectile, to distance of flight of the projectile. v
Fig. 5 is a graph showing the relation of linear force exerted by a mass within the rocket in response to linear acceleration and icentrifugal force existing on thatl body, both with respect to distance of flight of Vthe projectile.
In a typical rocket projectile there may be providedra casing 10, the nose portion of which may enclose a ymain explosive charge 11. To the rear of a transverse wall member 12 there may be a booster charge 14. Immediately to the rear of the booster charge there may be provided a wall member 15 having a central aperture within which is supported a lead 16 adapted to initiate ignition of the booster charge 14.
In accordance with this invention there is provided an arming mechanism consisting of a mass or weight member 17 pivotly mounted to casing 10 by means of a pin 18. It will be noted that the pin 18 should be located to one side of the center of gravity of weight 17. Since the direction of ight of the projectile will be to the right as shown in the drawings, the pin 18 is located forwardly of the center of gravity of the weight 17.
The weight 17 may be utilized as an arming mechanism by providing a suitable conventional detonator 19 located Within a bore in the weight 17 as shown in Fig. 1. In its normally disarming position, the detonator 19 is disposed vertically out of contact and out of line with the lead 16. The detonator is also completely isolated from a detonator initiating mechanism 20 supported on awall 21. The details of this mechanism 20 are not shown, as they may be conventional and it will be obvious to those skilled in the art that any conventional detonator may be utilized n in conjunction with this invention.
The weight 17 may be held in its normal disarming position in engagement with la stop member 22 mounted in v any suitable fashion on the interior surface-.of casing 10.
A spring 23 may be secured to Weight 17 and the interior surface of casing 10 normally to hold weight 17 in engagement with stop 22. The spring 23 is in the nature of a creep spring adapted to prevent any movement of weight 17 during shipment or other handling of the projectile prior to its being launched.
To the rear of the wall 21 which supports the detonator initiating mechanism 20 there is provided within casing 10 a rocket propulsion unit 24 in accordance with conventional practice.
In operation, it will be assumed that the rocket illustrated in Fig. l is of the spinning type and provided with any conventional mechanism or structure adapted to induce spinning of the rocket after it is launched. As the rocket motor is started thrust is built up in the rocket and accelerates it linearly along its course. If the spin inducing mechanism, such as angularly directed nozzles,
functions properly the rocket also accelerates angularly or commences toj spin with constantly increasing velocity. It might be noted that linear acceleration and angular iacceleration endure in a rocket until the fuel in the propulsion unit is consumed. As a result, the linear velocity V and the angular velocity W increase simultaneously.
Fig. 2 illustrates the relationship of linear acceleration and distance of ight. Thus the curve 25 illustrates in- In Fig. 'l of drawings, ai jfo'rce, line'FL' indicates' graphi-y cally the amount of linear force on `weight 17 during the init'ialiighty ofl the rocket. n
,Fig Y3 rof 'the drawings illustrates the relationship of angular velocity W to linearl distance of flight D. The
yresultant curve 26 shows constantly increasingangula velocity 'as the linear-'distance yof ight increases. f f Fig. `4shows`thei centrifugal force C existing on the weight 17,r which maybe calculatedhythe formula:
yFaro/V2 Where/Kris a constant, F is the force shown inPig. 2and yW; yis the angular velocity shownfin Fig.y 3.v Thus it is apparent that'the centrifugal force illustrated by thev curve f v27 increases substantially exponentially with linear dis- The centrifugalfforceline 'Fc shown in `Fig. k1 is' therefore substantially less than'the'linear forcer v during .the initial flight of the, projectile yand hence the f 'weight 17 maintains itsy normali positionfas vsl'iownin Pig.r
' 1 duringthe initialpart'of rthe vrockets tlight.r v y1 f v Fig.y 5 shows the force curvev 25 and centrifugal force` f curve 27 superimposed with respect to one another, and
from this figure itk will'be apparent kthat ythe linear forcev due to acceleration on the weight 17 equals the centrifugal f force on weight 17 aty somepre-determined distance from thelaunching point. At otherfdistances the linear force l kF is always greater or; always less than the centrifugal yt'orcefC.y It is also apparentzfro'm Fig. 5v that theangular velocity 'increases at some pre-determined distance from the launcher to sucha degree that the centrifugal force Since theline Fcis of greater length thany the iline FL'y this indicateslthat the centrifugal `force on weight 17 vexceeds the lineary force and'consequently the weight rotates into dotted line position in Fig. l, thereby aligning the detonator 19 with the detonator initiating mechanism 20 and the lead 16. When this occurs the rocket is fully armed. t It should be noted that no arming can occur unless the linear force and the centrifugal force on the weight 17 have increased to a pre-determined degree as indicated in Fig.v 5. Consequently the fuze-arming mechanism does not operate to arm the fuze unless the rocket example, the inventionmay be utilized to detonate the yr yis proceeding on its course with a pre-determinedlinear acceleration and a pre-determined angular acceleration ory velocity of spin. f
While the invention yhas, been disclosed with specicr reference to a fuze arming mechanism forfrockets, it will be readily apparent to .thoser skilled kin the art that the 'invention may also be utilizedy for initiating the action of any other mechanism within a spinningfprojectile. For
rocket when a pre-'determined ydegree of spin is attained.
v The invention claimed is:
In a spinning projectile, a casing having a nose porr tion, a detonatorfinitiating ymechanisml disposed rearywardly of said nose portion, an explosive charge in said nose portion, an arming mechanism disposed between said detonator initiating mechanism and said explosive v4`chargecomprising'a Aweight having a detonator disposed disa'rrning position where saidr detonator is out of line ywith said initiatingmechanism, andy anarming position where said major portion .extends `transversely vof said i casing andi said detonator isz aligned with said initiating f mechansim and said charge, a vstop member xed' to said 1 f C exceeds 'the lineal forcei Rand this is shown graphically by the force lines FL' and Fc in Fig. l.y f f lcasing `and extending radially vinwardly ythereof yinto en- `gagernent with said rmajor portion, and single spring means directly connectedfto saidfcasing and rsaid Weighty L to the 4rear ofisaidpin and tensioned normally 'to bias f said.` weight into engagement with said stop .member with its center ofy gravity to therear of` said pivot pin and said detonator out of line with said vinitiating mechanism, f
' whereby said Weight vrotates about said` pivot ypin from' said `dis-arming position to said arming position when angular acceleration of said vprojectile exceeds` linear acccleration. v v f References Cited in the le of this patent UNITED STATES PATENTS