GB2220468A - Very high velocity flare thrower - Google Patents

Description

VEM HIGH VEICCITY FUM 7HRMW DESCRIPTIM 0 0' The present invention relates

to a launcher or thrower of flashes or flares at very high velocities, i.e. several dozen kilometres per second. Such flares can be of interest for simulating impacts of well celestial bodies, for ballistic tests or for the study of controlled fusion by the sudden ccrrpressicn of the plasma by the impact of the flare.

Such velocities cannot be reached by simply placing a projectile upstream of an explosive charge in accordance with the principle of ordinary guns. It is therefore necessary to place a second projectLIc with a smaller mass than the first in the core or bore of the launcher, downstrearr, of the projectile. in accordance with we-U known shock equations (retention of the maTent= and energy), the downstream projectile acquires a higher velocity than the upstrearr.

projectile, if the integrity of said projectiles is retained after irrpact. It is therefore necessary that a very compressible light n-aterial is placed between the said projectiles.

This intermediate light rriaterial, whose compression attenuates the shock, thus prevents the spLintering of the dcwmstrea-, prr-jectile.

In place of the light material, use has alsc been rrade of an explo sive layer having essentially the sane properties but which also, as as result of its auto-ignition, makes it possible to constitute a propulsive stw,,e, which further accelerates the downstrearr. project-i- le.

The main problem which is then enc=tered is that the detonation of the explosive layer produces extremely high pressures exerted on the downstream projectile and which lead to the destruction thereof by melting. disintegration or even vaporization. This, in practice, the velocities whicl., can be reached by this process are liTited.

The invention makes it possible to obviate these disadvantages by a novel configuration of the explosive charge with zct to the B 9687.3 JCI downstream projectile, according to which between them is placed a layer of air or any other gas with a sufficiently low pressure. In practice, air at atmospheric pressure is suitable, although vacuturn leads to even better results.

The explosive charge is in fact detonated by contact with the upstream. projectile and the detonation products can then expand between the e%plosive charge and the downstream projecti-le. The compressibility of the gases is then much greater, so that the pressures transmitted to the downstream projectile are lower and in fact up to 4 tirres less. This is adequate to prevent any destruction of the dcw-nsti-,---arr, projectile.

It is then possible and advantageous to place downstream of saiii propulsive stage constituted by the explosive charge and the downstream projectile, other prcpulsive stages with a similar calstruc- tion, but of mnaller size, both with regards to the mass of the projectile and that of the explosive charge.. Launching or throwing then essentially ccaprises a succession of projectile wrpacts, each projectile accelerating the projectile positioned directly downstream. Velwities of several dozen kilometres per second can be obtained with an adequate number of propulsive stages.

The flashes or flares are either constituted by the actual downstream projectile, i.e. there is a single flare or flash thrower, or are carried by said dawnstrear. projectile, e.g. inserted in openings shape adapted in said projectile.

b In its most general form., the invention is therefore constituted by a thrower of at least one f lare at very high velocities and having, frai upstream, to downstream in a bore, an upstream explosive charge, an upstream projectile, then at least one propulsive stage, the propulsive stages succeeding upstream to downstream in the bore and each being constituted by an explosive charge, a projectile downstream of the explosive, a gap occupied by gas or vacu= extending B 9687.3 JCI between the explosive and the projectile, the projectiles having masses decreasing towards the downstream side and the flares are located on the furthest downstrean projectile.

Two train configurations will be described in greater detail herein after. In one of thar. the core or bore is cylindrical and the explosive charges are planar, in the same way as the projectiles, or plates. In the second configuration, the bore is conical and con verges towards the downstream side, whereas the explosive charges and plates are concave portions of cylinders or hollow spheres in an exerrp Lif ied rranner.

SaTpling rules are also given, which in particnila show that the pm:pulsj. ve stages advantageously have an identical geometrical configuration, to within the hamothetic transforactim.

Another objective of the inventive is to project the flares without disturbing the tests by the projection of undesired matter, e.g.

cx:rrdng f = the debris of the plate located furthest dcwnstrew and carrying the f Lares. For this purpose, it is possible to place down stream of said plate, a screen which is oblique with respect to the bore and which has openings facing the flares. During detonation, the screen is normally destroyed by the debris and projected in a direction close to that noimal to its surf ace, whilst the debris is deflected by the screen prior to its destruction in an opposite direction.

Fig. 4 The invention is described in greater detail hereinafter with respect to its various aspects in a non-limitative manner and with reference to the drawings, wherein show:

Fig. 1 A possible construction of the invention. Fig. 2 Another construction of the invention. Fig. 3 A possible configuration of the furthest downstream plate carrying the flares. Another possible ccnfiguratim of saird plate where there is only a single flare.

B 9687.3 JCI Fig. 5 A different construction of the launcher or thrower corc or bore.

is Fig. 1 shows the main cmpanents of the invention. Within the bore 1 are located from upstream to downstream an upstream detonating explosive charge 2, an upstream plate or projectile 3 and a certain number, in this case four, propulsive stages 4, and which in each case are constituted, from the upstream to the downstrear, side, by a detonating explosive charge 5, an air or vacuum. gap 6 and a plate 7. The bore 1 can be tubular, or is more generally constituted by a rigid structure, whose assaTuly ensures tkie fixing of its content and the longitudinal guidance of the plates 3 and 7. An assembly of longitudinal rods 15 connected by rings 16 (fig. 5) can also be suitable.

An unoccupied space 12 appears between each stage 4, which can be f i 1 led with air or vacuum and whose thickness is adequate to ens; ire that each plate 3 or 7 only strikes the explosive charge 5 of the following propulsive stage 4 after having been sufficiently accelerated. In this construction, the bore 1 is e.g. cylindrical and the projectiles 3 and 7 are planar plates, w-d-Ist the explosive charges 5, gaps 6 and unoccupied spaces 12 are also substantially planar volumes. The propulsive stages 4 taper frcrr, the upstream to the downstream side, the ratios of the thicknesses of the explosive charge 5, the gap 6 and the plate 7 being constant within each propulsive stage 4. In addition, tl-x-- ratio of tlie- thicknesses of the two ccaponents of the same space, e.g. the plates 7 is uniform between two consecutive propulsive stages 4, no rratter which stages are involved. TIis leads to a qeaTetrical confiauration 2.n which each propulsive stage 4 can be deduced fr= the preceding stages by a bcrmthetic trarisfonration of constant or slightly variable ratio between the individual stages.

The outer surface 8 of bore 1 has c-i=unfenmtia'L channels or narrm, deep groaves 9. As is explained by Fbnmch patent 87 16888, the shock wave produced by the detonation circulates faster in bore 1 than in B 968-7.3 X1 the interior thereof and leads to a contraction or pinching of bore 1, which jams the projectiles. Grooves 9 are intended to filter said shockwave.

The upstream explosive charge 2 partly projects beyond the outside of bore 1, tl-,e tl-zn,;er having no breech. The upstream explosive charge 2 is fired by a detonator 10 connected to a random firing device 11. This detonator firstly primes or starts a planar detonation wave generator 21 forming part of the upstream, explosive charge 2 and liarin; a lLrunw-.cd cone. shape.

As a function of the envisaged application, the flare which it is wished to throw or la.L-ich can be constituted by the furthest dOWMstream plate o.-E the th"rower or launchex, which, in this case is 107, or by smaller flares 20 included in said do%;nstream plate 107 and Eig. 3. As a function of needs, the flares 20 can have also shown in 16 different shapes and sizes. They are inserted prior to launching in the downstrear plate 107 after appropriate openings have been made therein and am detached fromn said plate 107 at the tim of the explosion. In the case when all that is sought is the inpact of flares 20 on a target 21 shown in f ig. I f acing bore 1, it can be of interest to place between bore 1 and target 21 a screen 22 which is positioned oblu-mely with. respect to borE 1 and -It-ie trajectory of flares 20. Screen 22 is e.g. connected to the downstream end of bore 1 by metal rods 23 and is provided with. openings 24 f acing the f lares 20 and paral I el to their traj ectories.

The launching or throwing of the f lares 20 takes place by acting an the firing device 11, which thus brings about the preferably planar detonation of the upstream explosive charge 2. The energy produced by this detonation in turn leads to the movement of the upstream plate 20, which passes through the first unoccupied space 12. An ct occurs with the explosive charge 5 of the f irst propulsive stage 4 and leads to the detonation of the latter. The explosive gase sp out at a xelatively low press= within the gap 6, so B 9687.3 JCI that plate 7 is accelerated without any excessive shock and is not destroyed by disintegration, melting or vaporization.

As plate 7 has a lower ness than the upstream plate 3, it is projected at a higher velocity, particularly as the explosive charge 5 irrparts to it a cinetic energy increase. The following explosive charge 5 is then detonated as soon as it is struck Ly. plate 7 and the process is repeated for all the propulsive stages 4 until the down- 2r stream plate 107 is finally reached. The flares 4, are then projected towards the target 21 in accordance with rectilinear trajectories 30 and reach the latter after passing through the openings 24. However, the other projectile fragments oric-inating frorr plates 3 and 7 are intercepted by screen22 against which they rebound before being deflected in accordance with paths.31. CpticnaLly, screen.22 is destrcyed by these nultiple Inpacts and its fra.,ts are projected along paths 32. Thus, as a result of the inclination oil screen 22, paths 31 and 32 pass outside the target 21, which is only reached by the flares 20.

However, screen 22 is not necessary. This is e.g. the case when the flare which it is wished to project is nothing r.cre than the actual downstream plate 107. Thiss is tr.e case -- the config=tior. according to fig. 4, where the dcxnstreaT plaze 2C7 is conical and not planar and is tldmed in its centre, where the single flare 220 is located.

This configuration of projectile -.2C7 is suitable when the plates 7 of the upstrea-. stages rebow-d cn the detonatior. products of the upstream charges 5 and 5'. Durinc, the explosion, downstream plate 207 f iistly defo=r-- and is then broken u:p Lnto fragrp-rits moved by a centrifugal velocity, which. progressively rroves tl,7jeT, aqay fl:aL the flare 220. The latter can be designed with an initial lozenge shape enabling it to deform during detonation and finally acquires a canvex leading edge 221 and a concc--ve trailing edge 222, which give it an aerodynanic: shape.

Another preferred construction of the invention is shown in fig. 2.

B 9687.3 XI Most of the elanents of fig. 1 again appear with. similar functions and different shapes. Thus, the bore or core 11 is conical and tapers towards the downstream end into a cone with an apex angle of approximately 60 and whose tip is very close to the dcx%Tistream plate 1071. Therefore the dcxsnstrea-,, plate 1071 has very snall dimensions canpared with the rest of the thrower, so that this solution is particularly suitable for a downstream plate 1071 carrying a single fLum 201.

The downstrear, plate 107 is quasi-planar and instal-led in a cylindrical mouthpiece 191 of bore V, whereas the rest of the inner surface 181 of bore 'L 1 is conical and the upstrec--, explosive charge 21, the upstrear projectile 3,1 and tIne cnents of the propulsive stages 41, i.e. ass he--c-inb,---F'ore and zuccessively, an explosive charge 51, a gap 61 and a projectile 71 are ho.Llaw spherical portions perpendicular to the inner surface 18' of bore 1'. The outer surface 81 of bore 11 has grooves 91, whilst several detonators 101 or preferably a spherical detonation wave generator (in cider to prcduce a shorter detonation c-' the upstrewr, explosive charge 2 1) are connected to a firing systEr 11'. Unoccupied spaces 121 are provided between the p--.Wulsive stages 41.

f 9 he Ihe operation of this wbodin-en.'t-- is identical to that O' f i. 1. T win difference is that the dowmstrearr. plate 1071 is accelerated with a higher energy and thus acquires a higher velocity, everything else being equal, than with the system according to fEig. 1. The cylindn:)conical or sphericoconical irrplosion does not make it possible to produce a larger nuTber of flares or flashes.

A caTparison between the constructions of figs. 1 and 2 can be made with the aid of tables 1 and 11, the first relating to a planar thrower with a cylindrical bore 1 and the second to a spherical thrower with a conical bore V.

In both cases the explosive.2z octcLUte and the projectiles are e from steel. The upstream explosive charge has a thickness of 400 z= B 9687.3 J= and the upstream projectile 16 rrrn. For each prqxazive stage, the ratio between the explosive mass per surface unit and the projectile mass per surface unit is equal to 0.5. The hcoothetic transfonmticn ratio (thickness of an elerrx-x,-,. of a propulsive stage to the corresponding thickness in the preceding prcpulsive stage) is equal to 0.4. In the case of table II, the external radius of the upstream explosive charge is 550 rwa. The tkdc}wies, of the gaps 6 is roughly one to two times that of the projectile 7 starting frui the second stage, in the sarrie way as the explosivc charges 5 & Thus, the tables I anG I! liLicate, as a function of the number of each propulsive stage 4, ti-ie thickness of the projectile of the propulsive stage in question and velocity which it reaches after detcn;Rt-ien. it ús clea that fez obtairdng high velocities, it is propulsive stages and that then necessary to increase the nurLer o. figuration is of much greater the sphericc>conic-::l:L-rplosior, con.

interest, because the thicknesses of the plates and the flares which it is wished to project are tha, rruch larger caTpared with.the planar configuration, in a ratio close to 2 as f=n the f=st stage and approximately 500 in Cic stage. For a large nuTber of stages, only the Inplosion conj'ic-Llrzit--Ljr, can be rea a ly envisaged. However, other concave siape--c o- 1-he projectiles 3' and 71 anC explosive layers 21 an 1 cw, IL..c used.

The air occupying gaps 6 ci: el pc.--nii: a forced expansion of the gases procluced by the cl ihe wcilosive charges 5 or 51, atmspheric pressure being suizable. Ever, better results are obtained if a vacaumn is produced in gaps 6 and 61. Air can also be replaced by any other gas.

B 9687.3 X1 TABW, 1 C1 %D Proive stage 0 1 2 3 4 5 0 7 8 9 10 nu 4 Thickness of projectile 16 6.4 2.56 1.025 0.41 0.165 0.0(11.1 0.026 0.01 0.004 0.0016 3 or 7 in nyn Velocity a"ired by 3.855 5.78 8.19 11.2 14.97 1q.68 25.5(, 32.92 42.12 53. 6 67.2 the projectile (knIs) TAPLU II Proive stage 0 1 2 3 4 5 6 7 8 9 10 number 4 ' Thickness of pmj(-ctile 16 11.78 8.68 6.4 4.715 3.47 2.56 1.88 1.39 1.02 0.75 311 or 71 in mm Velocity a " ired by 3.855 5.78 8.19 11.2 14.97 19.68 25.56 32.92 42.12 53.6 67.2 the projectile (bn/s) c L A IVIS 1. Thrower of at least one flare (20, 20 1) at very high velocities having, f=r,. the upstream to the downstrearn, side, in a bore (1, 11) 0 an upstrear c---.plosive charge (2, 21), an upstrear projectile (3, 31), at least one prcpul-cive stage (4, 4 1), the stages (4, 4 1 being in ez-ch case- corsti-,uttcl- ty w. c]7z=,e (5, 51) and a the explosive (_) prcjec-L.-UE: (7, V) cj 5, 51), the projec t--lcs (2, -"', 7, V) msse-s decrec--=ir.c: to;azt.s the downstrean side =d the f-lares (2C, 2K 1) '--c-4-,c- located on the furthest downstrearn projectile (10, 1071), cl-,aractwize:l in that the propulsive stages are alsc constituted by a ciEl, 6 occupied ty gas or vacLur.

J') an-7 the projectile (7, 71).

tct:.oeer. tIne c Extending 2. Th=er of at least one fl=re at very high velocities according to clr--,!.n 1, characterized in t17z;t the bore is a riaid structure enRirine: the fixing c.E the prcpulsive stages (4, V) of the upstream is explosive charge and the upstrew- p--.TjectilF-.

3. Thrower of at leas-IC one flare at very high velocities according - the bore (1) iss cylindrical.

to claim 1, characterized Ln that 4. of at least one- &E1,7rE az ver,. ve-',oc-Jties according to clainn 1, characterize= ir ti-t the bore (1) is conical and narrows towards the dcx..nstrea:- side.

5. Thrower of at least one flare at very high velocities according to any one of the cla:LTs -1, 3 or 4, characterized in that the projectiles (3, 7) and e>plos2.ve- cl=ges (5) are planar.

6. Throw= of at least = flare at very high velocities according to any one of the cla:LTs 2 to 5, characterized in that the projectilm (31, 71) and explosive charges (51) are concave.

7. Thrower of at least one flare at very high velocities according to any one of the claiffs 1 to 6, characterized in that the propulsive B 9687.3 X1 stages (4, 4 1) have an approximately identical gen, trical configuration to within the hamothetic transfo=mtien.

8. Thm,;er of at least one flare at very high velocities according to any one of the claims 1 to 7, characterized in that the flares (20) are inserted in cutouts of C furthest downstream plate (107).

9. Thirm.er o.'iO at least cne flare at very high velocities according to clatr. 8, in which there is cnly a single f lare, char acterized in 1 th that thú flare (220) is located in a cutout in the centre o e furt.hest dcm-nslirearr, plate (207), which thins towards its centre.

10. Thrnwer of at least one flare at very high velocities according to any one of the clal::m 1 to 9, characterized in that the gas oc=Yir.-, the gaps (6, 6 1) is at a press= bet,ewi at-ospheric pressure and vact=..

11. Th=wer of at least one f Ia- at very hich velocities according to any one of the clakm 1 to 8, ch=cterized in that a screen (22) is placed dcwnstz-r--a-n of the f=thest dcmnstreaT plate, cblicuely with respect to the bore and Ln that the screen has =w.incs (24) facing each of the flax-es (20).

12. A flare thrower substantially as described herein with reference to the accompanying drawings.

E 9687.3 J= Published 1989 at The Patent Office. State House. 66 71 High Holborn. London WCI R 4TP Further copies maybe obLained frorn The PatentOffice Sales Branch, S Mary Cray. OrpingtoL. Rent BR5 3111) Pz=ted by Multiplex Lecbluques ltd- St Id&-y Cray. Kent. Con. 1'87