US3678854A - Flare body - Google Patents

Flare body Download PDF

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Publication number
US3678854A
US3678854A US831167A US3678854DA US3678854A US 3678854 A US3678854 A US 3678854A US 831167 A US831167 A US 831167A US 3678854D A US3678854D A US 3678854DA US 3678854 A US3678854 A US 3678854A
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United States
Prior art keywords
flare
composition
combustion
burning
wire netting
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.)
Expired - Lifetime
Application number
US831167A
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English (en)
Inventor
Ragnar Per-Olof Davidson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saab Bofors AB
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Bofors AB
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Publication date
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Publication of US3678854A publication Critical patent/US3678854A/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B4/00—Fireworks, i.e. pyrotechnic devices for amusement, display, illumination or signal purposes
    • F42B4/26—Flares; Torches

Definitions

  • a flare has a cylindrical body composed of a solid combustible June I0, 1968 Sweden ..7796/68 p is wlth a non-combustible and heat-resistant covering and the 521 [1.5. cu. ..1oz/37.a, 102/!02 My is 51 Int. Cl. ..C06d 1/10 and highly heat-resistant Win s its mire lenslh [58] Field of Search 102/3 7.8, 35, 102, 103 The n ing n s nti lly ush with the other end wall of the body. Ignition of the flare composition is started at this [56] References Cited other end wall.
  • the wire netting prevents direct access of combustion flames to the side wall of the body thereby imped- UNITED STATES PATENTS in; premature burning at localized areas of the side wall.
  • 02/37.8 UX also provides a multitude of passages for the flow of fresh l,486,0 l 4 3/1924 Dutcher.... ....i02/37.8 X combustion air to the burning composition so that the same is 1,539,692 3/1925 aulus 102/373 gradually and uniformly consumed whereby the luminous efi'i- 3,l44,830 8/1964 De Fries et al... 102/103 i y f the flare is markedly increased. 3,311,013 3/1967 Phipps .102/102 x 3,367,268 2/1968 Spenadel et al l02/l02 9 Claims, 5 Drawing figures Patantod July 25, 1972 3,678,854
  • the present invention relates to an improvement in flare bodies, i.e. bodies having a normally pressed flare composition comprising e.g. magnesium and an oxygen producing substance. These bodies, alter having been carried to a considerable height above the ground by means of a projectile or an airplane and ignited, fall towards the ground in a parachute during which time the flare composition generates light in order to illuminate the ground surface.
  • flare bodies i.e. bodies having a normally pressed flare composition comprising e.g. magnesium and an oxygen producing substance.
  • Such flare bodies are well known and initially a pressed flare composition was used which was ignited at one end by activating of an ignition device in any suitable manner.
  • a pressed flare composition was used which was ignited at one end by activating of an ignition device in any suitable manner.
  • the ignited and burning flare composition during the downward movement has such a great velocity relative to the surrounding atmosphere (e. g. a drop velocity of 5 m/sec.) that while the combustion is started at the end of the flare composition facing the ground the flame which occurs during the combustion sweeps upwardly along the flare composition and causes ignitions at non-desired places on the flare composition.
  • the flare composition consists of a circular cylinder with end faces at right angles to the axis of the cylinder takes place in axial direction and with substantially constant and equal velocity over the whole burning surface which moves successively in the direction of the axis of the cylinder and which thus is substantially plane and perpendicular to the axis of the cylinder.
  • the flare composition together with the surrounding insulation is encased in a sleeve or a casing of steel which surrounds the flare composition in substantially the same way as the insulation, i.e. leaves free only the end surface of the flare composition of the circular cylindrical flare body facing the ground, there is obtained a considerable increase of the total light amount produced during the burning time.
  • the reason therefore seems to depend on the fact that by the combustion of the flare composition in the previously mentioned conventional way with the burning surface substantially plane and perpendicular to the axis of the cylinder, the surrounding steel casing will successively project with its free edge in front of the burning surface and thus a kind of nozzle which directs the flame produced at the combustion in the direction of the axis of the cylinder and out from the steel casing.
  • FIG. 1 shows diagrammatically the conditions during the burning time of a prior flare body and provided with an insulatron.
  • FIG. 2 shows in the same way the conditions during the burning time of another prior art flare body and provided with a steel casing.
  • FIG. 3 is a bottom view of a flare body according to the present invention from the end provided with the ignition device and for sake of clarity with the insulation and wire-net overdimensioned.
  • FIG. 4 is a side section view of the flare body according to FIG. 3.
  • FIG. 5 is a perspective view, partly cutaway, of the flare body FIG. 4.
  • the previously known flare body according to FIG. 1 has a flare composition 1 and it is assumed that it has burnt for so long a time that the used ignition device does not remain.
  • a holding means 3 is provided for the connection of the flare body to a parachute (not shown) and the insulation adapted for obtaining a uniform progressing combustion and which for instance consists of plastic material with a filler in the form of for instance MgO or asbestos is designated 4. It is to be observed that the thickness of the insulation is very exaggerated. The flames occurring during the combustion are deflected outwardly by the influence of the drag and this is diagrammatically shown by the lines a.
  • the produced smoke is indicated by the dotted line r and it is evident that smoke is located between the flare body and the ground, as the descentdirection of the flare body is substantially (except for swinging movements or the like) that indicated by the arrow f. It is obvious that the insulation protects the rear sections of the flare body from being ignited by the flames shown by the lines a.
  • FIG. 2 there is shown in the same manner as in FIG. I the conditions at a flare body with a connection means 3, a flare composition 1 and a surrounding steel casing 5.
  • a certain burning time there is obtained a remaining edge portion 5a of the steel casing which edge portion extends beyond the burning flare composition 1 and causes the formation of a fierce flame diagrammatically shown by the bent lines b.
  • the drag also in this case the descent-direction is indicated by the arrow f causes a deflection of the outer free end of the fierce flame and the occurrence of the produced smoke behind the deflected fierce flame, as is diagrammatically indicated by the dotted line r,.
  • a wire net with suitable mesh and wire thickness is not only able to act as a nozzle but also may assist the fierce flame, flowing out through the forward opening in the wire net, to draw secondary air through the meshes of the wire net.
  • the effect hereof is that probably a certain turbulence which improves the combustion, arises in the burning zone immediately in front of the end surface of the flare composition, and that the oxygen in the drawn in air causes a more complete combustion of the material of the flare composition which in the present case preferably has a deficit of oxygen (relative to the amount of magnesium in the flare composition) and that for this reason a greater total amount of light is produced for a certain amount or weight of the flare composition than if for instance there is excess of oxygen in the flare composition.
  • the metal wire net is combined with an insulation known per se, which now can be made comparatively thin.
  • An embodiment of a flare body of this kind is shown in FIGS. 3, 4 and 5 in which there is a flare composition 1, an ignition device 2 and a connection means 3.
  • the flare composition is at the cylinder surface surrounded by metal wire net 6 which by means of an insulation layer 4a is separated from the flare composition 1.
  • This insulating layer 4a may be thin.
  • the metal wire net is moulded into the insulation which thus consists of a first layer 4a between the net 6 and the flare composition and a second layer 4b outside the net 6.
  • Said insulation may consist of the same plastic material with filler in the form of MgO or asbestos, as is already mentioned.
  • FIG. 3 An embodiment of a flare body of this kind is shown in FIGS. 3, 4 and 5 in which there is a flare composition 1, an ignition device 2 and a connection means 3.
  • the flare composition is at the cylinder surface surrounded by metal wire net 6 which by means of an insulation layer 4a
  • the flare body is in the form of a circular cylinder.
  • the invention is not limited to flare bodies with the flare composition in the shape ofa cylinder or a circular cylinder, although these shapes are the most commonly used.
  • the action of the metal net is especially advantageous in connection with the use ofa thin insulation and a flare composition having a deficit of oxygen as regards the oxygen-containing material in the flare composition in comparison to the amount of magnesium or possibly a substance of another metal or another compound which forms the material intended for the combustion.
  • a flare body having a diameter of 70 mm and an initial length of 90 mm and a circular cross section and using only one plastic insulation a total light yield of about 8 millions candela seconds
  • a hitherto much used embodiment produces an average light yield of about 20-22 millions candela seconds.
  • a net of stainless steel with a diameter of about 0.25-0.l0 mm and meshes of 1.0-2.0 mm, i.e. corresponding to l4-l 8 mesh, or meshes of 0.5 mm light yield values of more than 30 millions candela seconds have been obtained.
  • a favorable result has also been achieved with meshes as small as 35 mesh.
  • the optimal values for the wire net are normally obtained by using a thread having a diameter of 025-1 .0 mm. and a free mesh ofabout l.02.0 mm.
  • a flare comprising an elongate body composed of a solid combustible flare composition, said body having end walls normal to the longitudinal axis of the body;
  • a non-combustible and heat-resistant wire netting encompassing the side of the body along the length thereof and terminating substantially flush with the other end wall of the body;
  • ignition means at said other end wall for initiating combustion of the flare composition at said end;
  • a protective heat-insulating layer interposed between the wire netting and the flare composition encompassing the netting and the composition along the lengths thereof, said protective layer being composed of a mixture of plastic and a heat-insulating filler material,
  • said wire netting and protective layer upon ignition of the composition preventing direct access of combustion flames to the side of the body thereby impeding premature burning at localized areas of the side, said netting also providing a multitude of passages for the flow of fresh combustion air to the burning body thereby causing a gradual an uniform consumption of the body thus increasing the luminous efliciency of the flare.
  • said wire netting is formed of wires having a diameter of 0.25 to 1 mm and has free meshes about 0.5 to 2.00 mm. 5

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Insulation (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
  • Gas Burners (AREA)
  • Professional, Industrial, Or Sporting Protective Garments (AREA)
US831167A 1968-06-10 1969-06-06 Flare body Expired - Lifetime US3678854A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE7796/68A SE312086B (da) 1968-06-10 1968-06-10

Publications (1)

Publication Number Publication Date
US3678854A true US3678854A (en) 1972-07-25

Family

ID=20272338

Family Applications (1)

Application Number Title Priority Date Filing Date
US831167A Expired - Lifetime US3678854A (en) 1968-06-10 1969-06-06 Flare body

Country Status (5)

Country Link
US (1) US3678854A (da)
FR (1) FR2010581A1 (da)
GB (1) GB1242327A (da)
IL (1) IL32364A (da)
SE (1) SE312086B (da)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4064805A (en) * 1975-05-23 1977-12-27 Ab Bofors Device for pyrotechnical illuminating charge
US4615271A (en) * 1984-07-31 1986-10-07 Royal Ordnance Plc Shock-augmenting charge with axially-grooved booster housing
US4764319A (en) * 1986-09-18 1988-08-16 Morton Thiokol, Inc. High solids ratio solid rocket motor propellant grains and method of construction thereof
EP0247013A3 (en) * 1986-05-23 1991-11-27 Aktiebolaget Bofors A flare charge insulation, a method of its manufacture and a flare charge manufactured according thereto
WO2009127309A1 (de) * 2008-04-18 2009-10-22 Rheinmetall Waffe Munition Gmbh Wirkkörper für eine submunition mit wirkmitteln

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE437300B (sv) * 1976-10-27 1985-02-18 Bofors Ab Lyskropp avsedd for militera endamal
DE102013010266A1 (de) * 2013-06-18 2014-12-18 Diehl Bgt Defence Gmbh & Co. Kg Scheinzielwirkkörper mit einer pyrotechnischen Wirkmasse

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1205928A (en) * 1916-05-29 1916-11-21 Central Railway Signal Co Time-burning railway signal-fusee.
US1486014A (en) * 1921-11-12 1924-03-04 Central Railway Signal Co Flare light
US1530692A (en) * 1923-06-27 1925-03-24 Charles L Paulus Reenforced pyrotechnic flare
US3144830A (en) * 1964-08-18 Solid propellent grains
US3311013A (en) * 1963-01-09 1967-03-28 Aerojet General Co Propellant liner
US3367268A (en) * 1959-10-05 1968-02-06 Exxon Research Engineering Co Hybrid rocket propellent grain

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3144830A (en) * 1964-08-18 Solid propellent grains
US1205928A (en) * 1916-05-29 1916-11-21 Central Railway Signal Co Time-burning railway signal-fusee.
US1486014A (en) * 1921-11-12 1924-03-04 Central Railway Signal Co Flare light
US1530692A (en) * 1923-06-27 1925-03-24 Charles L Paulus Reenforced pyrotechnic flare
US3367268A (en) * 1959-10-05 1968-02-06 Exxon Research Engineering Co Hybrid rocket propellent grain
US3311013A (en) * 1963-01-09 1967-03-28 Aerojet General Co Propellant liner

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Military Pyrotechnics Series (M.P.S.); Part 3; AMC Pamphlet; AMCP October 1963; pp. 185 188 (especially p. 188). *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4064805A (en) * 1975-05-23 1977-12-27 Ab Bofors Device for pyrotechnical illuminating charge
US4615271A (en) * 1984-07-31 1986-10-07 Royal Ordnance Plc Shock-augmenting charge with axially-grooved booster housing
EP0247013A3 (en) * 1986-05-23 1991-11-27 Aktiebolaget Bofors A flare charge insulation, a method of its manufacture and a flare charge manufactured according thereto
US4764319A (en) * 1986-09-18 1988-08-16 Morton Thiokol, Inc. High solids ratio solid rocket motor propellant grains and method of construction thereof
WO2009127309A1 (de) * 2008-04-18 2009-10-22 Rheinmetall Waffe Munition Gmbh Wirkkörper für eine submunition mit wirkmitteln
US20110088582A1 (en) * 2008-04-18 2011-04-21 Rheinmetall Waffe Munition Gmbh Active body for a submunition having effective agents

Also Published As

Publication number Publication date
GB1242327A (en) 1971-08-11
IL32364A (en) 1973-04-30
DE1929170A1 (de) 1969-12-11
DE1929170B2 (de) 1976-07-08
IL32364A0 (en) 1970-03-22
FR2010581A1 (da) 1970-02-20
SE312086B (da) 1969-06-30

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