EP0870166A1 - Launch pack - Google Patents
Launch packInfo
- Publication number
- EP0870166A1 EP0870166A1 EP96938553A EP96938553A EP0870166A1 EP 0870166 A1 EP0870166 A1 EP 0870166A1 EP 96938553 A EP96938553 A EP 96938553A EP 96938553 A EP96938553 A EP 96938553A EP 0870166 A1 EP0870166 A1 EP 0870166A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electric sliding
- fibres
- sliding contact
- casing
- launch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B6/00—Projectiles or missiles specially adapted for projection without use of explosive or combustible propellant charge, e.g. for blow guns, bows or crossbows, hand-held spring or air guns
- F42B6/006—Projectiles for electromagnetic or plasma guns
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B6/00—Projectiles or missiles specially adapted for projection without use of explosive or combustible propellant charge, e.g. for blow guns, bows or crossbows, hand-held spring or air guns
Definitions
- the present invention relates to a launch pack for accelerating projectiles to hypervelocities in an electromagnetic accelerator, comprising a casing in which at least one electric sliding contact is arranged, which sliding contact is formed by multiple fibres of an electrically conducting material onto which an electrically insulating material has been applied, the fibres running from the top to the bottom of the casing.
- a launch pack of this type is known in practice from research and can, for example, be used to launch projectiles for military purposes at velocities of up to 4 km/s. In this context use is often made of an electromagnetic rail accelerator which operates repeatedly.
- a known problem is that spark erosion occurs in the first part of the launch process, in which the launch pack is accelerated from stationary to the so-called transition velocity. During this phase the ends of the fibres wear away. When the transition velocity is reached, a fluid and/or metallic plasma boundary layer is then produced by the high generation of heat at the contact surface between the electric sliding contact and the rails. During this phase the ends of the fibres wear away further, the length of the fibres is reduced and the solid-solid electric sliding contact surface becomes a hybrid sliding contact surface.
- the abovementioned effects give rise to inefficient energy transfer between the accelerator and the launch pack and, furthermore, lead to undesired damage to, and excessive wear of, the accelerator.
- the result of this is that the maximum achievable velocities with launch processes of this type are limited and the accelerator is usable only a limited number of times.
- the aim of the invention is to overcome the abovementioned disadvantages.
- the launch pack according to the present invention is characterised in that the length of the fibres is essentially greater than the height of the casing to such an extent that a feed mechanism is provided to compensate for wearing away of the ends of the fibres.
- the nature of the feed mechanism is that there is compensation, during acceleration, for the length of the fibres lost as a result of the ends of the fibres wearing away by erosion.
- the extra length of the fibres also ensures that the mechanical pretensioning at the contact surface is maintained, postponing the occurrence of spark erosion. Consequently, with the launch pack according to the invention there is a controlled, gradual transition from a solid-solid moving electric sliding contact to a sliding contact with a fluid and/or metallic plasma boundary layer with the stationary electrical conductor. In addition, current is fed through the contact surface virtually free from spark erosion.
- two or more electric sliding contacts are, viewed in the longitudinal direction of the launch pack, placed essentially one after the other and at least partially spatially separated from one another, such that the orientation of the electric sliding contacts within the casing is essentially identical.
- two or more electric sliding contacts viewed in the transverse direction of the launch pack, are positioned essentially alongside one another and at least partially spatially separated from one another.
- the present invention also relates to a method for the production of an electric sliding contact, as described, as a component of the launch pack according to the invention, the method comprising the following steps: (a) applying an adhesive to a winding core, the shape of which is matched to the shape desired for the rear of the electric sliding contact;
- the method according to the invention has the advantage that the winding technique leads to an electric sliding contact of an approximately uniform density. No further filling is needed for homogenisation of the electric sliding contact produced in this way, with the result that wastage of material is counteracted.
- the present invention also relates to an electric sliding contact obtained by use of the method, wherein the fibres make up 75 % to 85 % of the volume of the electric sliding contact.
- the present invention also relates to a method for the production of a launch pack, wherein a casing of, preferably, fibre-reinforced material is arranged around one or more electric sliding contacts obtained by use of the method described above, the dimensions of said casing being matched to the dimensions of the accelerator, and wherein empty spaces inside the launch pack are filled with the aid of a filler material of high compressive strength and high temperature stability.
- Figure 1 shows a simplified diagram showing the principle of a rail accelerator
- Figure 2 shows a longitudinal section of a first embodiment of a launch pack according to the present invention
- Figure 3 shows a cross-section along the line III-III in Figure 2;
- Figure 4 shows a cross-section of a rail accelerator in which a second embodiment of the electric sliding contacts of a launch pack according to the present invention is shown diagrammatically;
- Figure 5 shows a top view of a possible installation for carrying out the method according to the present invention.
- Figure 1 shows a simplified diagram showing the principle of a rail accelerator 1.
- Rail accelerator 1 is an electromagnetic accelerator provided with rails 2 which serve as electric guides for the projectile 4 to be launched. With the aid of a pulsed electric power supply 3. a current I of the order of magnitude of a few MA is passed through rails 2 and launch pack 5 for the projectile . Current I, in conjunction with magnetic field B, provides a resultant Lorentz force F on the projectile 4, which is accelerated as a result. In the future it will, for example, be possible to use a rail accelerator of this type for repeated electromagnetic launches of projectiles to hypervelocities ⁇ up to 4 km/sec) for military tactical applications.
- FIG 2 shows a longitudinal section of a first embodiment of a launch pack 5 according to the invention.
- Figure 3 shows a top view of a cross-section, along the line III-III, of the launch pack according to Figure 2.
- launch pack 5 comprises multiple electric sliding contacts 6 around which a casing 7 is arranged, such that the electric sliding contacts 6 make contact with rails 2. Empty spaces between the electric sliding contacts 6 have been filled with the aid of filler material 8.
- Each electric sliding contact 6 consists of a number of fibres of an electrically conducting material onto which an electrically insulating material has been applied. Examples of a suitable electrically conducting material are copper, aluminium and molybdenum.
- the electrically insulating material used is, for example, polyester-imide.
- the fibres preferably run from the top to the bottom of the casing 7 essentially parallel to one another, said fibres having the shape of the electric sliding contact 6.
- the fibres are at an angle to one another (not shown).
- This anisotropic resistance distribution can, for example, be obtained by the use of fibres running parallel to one another. In connection with an optimum heat balance, the thermal separation between the fibres must preferably be as small as possible. Furthermore, in order to prevent the formation of microsparks in the contact surface, an optimum number of contact spots per unit surface area in the contact surface is desirable. This can be achieved, for example, by means of a suitable choice of the fibre diameter (preferably between 40 and 100 ⁇ m) and a suitable choice of the insulating material.
- the length of the fibres has been chosen to be sufficiently greater than the height of the casing 7 in order to provide a feed mechanism to compensate for wearing away of the ends of the fibres during the launch process.
- the length of the fibres is chosen such that the feed mechanism is available in use essentially throughout the entire launch process.
- the feed mechanism produced is further supported by the fact that the thermally softened fibres stretch as a consequence of the
- each electric sliding contact 6 makes (make) an angle ⁇ with the casing 7.
- angle ⁇ not being equal to 90° .
- angle ⁇ is approximately the same for all fibres in an electric sliding contact 6.
- ⁇ 45 ⁇ 5 •
- each electric sliding contact 6 has a mid section 6a which runs essentially perpendicular to the casing 7.
- arms 6b being fixed to, respectively, the top and the bottom of the mid section 6a, which arms 6b run at an angle ⁇ in a direction opposite to the direction of movement, p" is preferably given by 15 ° ⁇ ⁇ ⁇ 25°.
- the launch pack 5 comprises at least one electric sliding contact 6, but, if desired, can be extended by placing multiple electric sliding contacts one after the other, and at least partially spatially separated from one another, in the longitudinal direction of the launch pack 5.
- the orientation of the electric sliding contacts 6 inside the casing 7 being essentially identical, as is shown in Figure 2.
- An optimum current distribution can be obtained by extending the launch pack in the abovementioned manner by means of segmentation. Said length optimisation also makes it possible to use a longer rail accelerator, as a result of which spark erosion-free acceleration can be achieved over a longer path.
- the optimum length l x of each electric sliding contact 6 is related to the diffusion length of the magnetic field B in the electric sliding contact as a result of the "velocity skin effect" and the temperature dependence of the specific resistance of the fibre material used and the shape of the electric sliding contact.
- the dimensions of the electrical part of the launch pack are dependent on, inter alia, the calibre and the shape of the bore of the accelerator concerned as well as on geometrical requirements which are imposed in connection with fitting the launch pack in a projectile.
- An optimum length can, if desired, be obtained by placing a number of sliding contacts one after the other. It can be pointed out that the height of the casing 7 is preferably approximately equal to the distance between the rails 2 of accelerator 1.
- 1 2 for arms 6b is preferably equal to or less than 7 Oin.
- the dimensions are matched to a rail accelerator which has a bore of 20 mm.
- Casing 7 is preferably produced from a fibre-reinforced plastic material and materials of this type are generally known to those skilled in the art. In general they comprise reinforcing fibres, such as carbon fibres, aramide fibres (Kevlar , Twaron ) or other reinforcing fibres, which are incorporated in a matrix or are glued by means of an adhesive or binder, such as epoxy adhesive.
- the casing is preferably produced from a fibre material which is obtained by winding, preferably at a winding angle of between 80 and 85°, the wound layer being bonded to itself by means of a minimum amount of adhesive, for example an epoxy adhesive.
- the casing is fitted using a force fitting.
- the filler material 8 used is preferably a material of high compressive strength and high temperature stability, such as boron nitride, aluminium oxide, glass fibre-reinforced epoxy material (G10) or materials to influence the penetration of the magnetic field, such as ⁇ -metal.
- Figure 4 shows a diagrammatic representation of a possible second embodiment of a launch pack according to the invention. The only parts of the electrical part of the launch pack which have been drawn in cross-section are the two electric sliding contacts 6' positioned alongside one another in the transverse direction thereof. The electric sliding contacts 6' are at least partially spatially separated from one another. It can clearly be seen that the fibres in the electric sliding contacts 6' are curved outwards and taper together towards the raiDs 2.
- a current I runs through the two electric sliding contacts 6' , as a result of which opposing Lorentz forces F, and F 2 , respectively, act on the two electric sliding contacts.
- the electric sliding contacts 6' thus attract one another, a pressure being exerted on the rails 2 as a result of the curved shape of said sliding contacts. The effect of this is to promote the abovementioned feed mechanism.
- the first embodiment (shown in Figure 2) and the second embodiment (shown in Figure 4) of the electric sliding contacts 6 and 6' can be integrated.
- FIG. 10 shows a top view of an installation to illustrate the method according to the present invention.
- Installation 10 comprises a winding core 11, the shape of which is matched to the shape desired for the rear of an electric sliding contact.
- An adhesive preferably a thermoplastic two-component adhesive having a softening temperature of ⁇ 120 ° C, is first applied to winding core 11.
- a layer of fibres 12 of a suitable material preferably having a diameter of between 40 and 100 ⁇ m
- a layer about 0.5 m thick is wound.
- the adhesive is then applied to the wound layer, after which a subsequent layer of fibre material is wound in the same way on top of the layer which has already been wound, etc. This process is repeated until a desired thickness for the electric sliding contact has been obtained.
- Clamping plates 13 the shape of which is matched to the shape desired for the front of the electric sliding contact, are then applied approximately symmetrically around the axis of the winding core 11 in order to clamp the fibre material 12.
- the whole is then heated to a temperature which is higher than or equal to the softening temperature of the adhesive (for example 120
- the whole is then cooled to room temperature.
- the resultant wound product consisting of fibre material 12 is then removed from installation 10 and can be subdivided into a number of electric sliding contacts of essentially the same dimensions.
- the electric sliding contacts 6 as shown in Figure 2 are produced by dividing the wound product into four equal parts.
- the winding core 11 and the clamping plates 13 can be provided with a protective layer, for example a 0.1 mm thick layer of Teflon tape.
- a protective layer for example a 0.1 mm thick layer of Teflon tape.
- the clamping plates can optionally be fixed in place with the aid of bolts.
- the dimensions and shape of the components of installation 10 can, of course, be adapted to the desired final shape of the electric sliding contacts to be produced.
- it is also possible to make electric sliding contacts by this method which are suitable for use in a rail accelerator having, for example, a circular bore.
- the method according to the invention has the advantage that the fibre material 12 can be wound so compactly that the fibres in the electric sliding contacts are able to make up 75 % to 85 % of the volume thereof.
- the electric sliding contacts produced in this way are therefore virtually homogeneous, but nevertheless have the requisite anisotropic resistance distribution.
- a further advantage of the method according to the invention is that virtually all of the wound fibre material is used; there is thus hardly any question of material wastage.
- fibres in combination with an adhesive gives the electric sliding contacts according to the invention the necessary give to be able to absorb slight deformations of the accelerator during the acceleration process and, as a result, to allow the feed mechanism to function in an optimum manner as the ends of fibres wear away during the acceleration process.
- a fine pulverulent ceramic material can be added to the adhesive.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Plasma & Fusion (AREA)
- Plasma Technology (AREA)
- Laminated Bodies (AREA)
- Current-Collector Devices For Electrically Propelled Vehicles (AREA)
- Particle Accelerators (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1001710A NL1001710C2 (en) | 1995-11-21 | 1995-11-21 | Launch package. |
NL1001710 | 1995-11-21 | ||
PCT/NL1996/000461 WO1997019315A1 (en) | 1995-11-21 | 1996-11-21 | Launch pack |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0870166A1 true EP0870166A1 (en) | 1998-10-14 |
EP0870166B1 EP0870166B1 (en) | 2000-03-01 |
Family
ID=19761891
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96938553A Expired - Lifetime EP0870166B1 (en) | 1995-11-21 | 1996-11-21 | Launch pack |
Country Status (10)
Country | Link |
---|---|
EP (1) | EP0870166B1 (en) |
JP (1) | JPH11515083A (en) |
KR (1) | KR19990071501A (en) |
AU (1) | AU702837B2 (en) |
DE (1) | DE69606889T2 (en) |
IL (1) | IL124504A (en) |
NL (1) | NL1001710C2 (en) |
NO (1) | NO982216L (en) |
PL (1) | PL326749A1 (en) |
WO (1) | WO1997019315A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2879032B1 (en) * | 2004-12-02 | 2008-02-29 | Saint Louis Inst | MOBILE ELECTRIC CONTACT DEVICE WITH CONDUCTOR RESERVE |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4369692A (en) * | 1979-12-04 | 1983-01-25 | Westinghouse Electric Corp. | Switching system for high DC current |
US4457205A (en) * | 1981-12-09 | 1984-07-03 | Westinghouse Electric Corp. | Multiple fiber armatures for electromagnetic launchers |
US4576082A (en) * | 1982-12-23 | 1986-03-18 | Westinghouse Electric Corp. | Linear fiber armature for electromagnetic launchers |
US4658729A (en) * | 1984-09-20 | 1987-04-21 | Westinghouse Electric Corp. | Modular fiber armature for electromagnetic launchers |
-
1995
- 1995-11-21 NL NL1001710A patent/NL1001710C2/en not_active IP Right Cessation
-
1996
- 1996-11-21 EP EP96938553A patent/EP0870166B1/en not_active Expired - Lifetime
- 1996-11-21 IL IL12450496A patent/IL124504A/en not_active IP Right Cessation
- 1996-11-21 WO PCT/NL1996/000461 patent/WO1997019315A1/en not_active Application Discontinuation
- 1996-11-21 KR KR1019980703773A patent/KR19990071501A/en not_active Application Discontinuation
- 1996-11-21 PL PL96326749A patent/PL326749A1/en unknown
- 1996-11-21 JP JP9502366A patent/JPH11515083A/en active Pending
- 1996-11-21 AU AU75907/96A patent/AU702837B2/en not_active Ceased
- 1996-11-21 DE DE69606889T patent/DE69606889T2/en not_active Expired - Fee Related
-
1998
- 1998-05-15 NO NO982216A patent/NO982216L/en unknown
Non-Patent Citations (1)
Title |
---|
See references of WO9719315A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1997019315A1 (en) | 1997-05-29 |
KR19990071501A (en) | 1999-09-27 |
NL1001710C2 (en) | 1997-05-23 |
DE69606889T2 (en) | 2000-10-05 |
IL124504A0 (en) | 1998-12-06 |
PL326749A1 (en) | 1998-10-26 |
JPH11515083A (en) | 1999-12-21 |
NO982216D0 (en) | 1998-05-15 |
AU702837B2 (en) | 1999-03-04 |
DE69606889D1 (en) | 2000-04-06 |
NO982216L (en) | 1998-07-16 |
AU7590796A (en) | 1997-06-11 |
IL124504A (en) | 2000-08-31 |
EP0870166B1 (en) | 2000-03-01 |
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