US3861307A

US3861307A - Flare arrangement

Info

Publication number: US3861307A
Application number: US418798A
Authority: US
Inventors: Jr Charles J Litz
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1973-11-23
Filing date: 1973-11-23
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21

Abstract

An aircraft self-sustaining flare that provides a reference source of illumination, operating at a constant altitude and being relatively insensitive to wind drift. The flare arrangement employs a whirling rotor blade structure that is driven by pressure gas produced by a gas generator mounted in the central portion of a combustible flare tube intermediate a pair of longitudinally spaced cylindrical flare propellant grains. Electrical ignition means ignite the gas generator and the end surfaces of the flare propellant grains.

Description

Muted [1 1 [111 3,861,307 Litz, Jr. Jan. 21, 1975 [5 FLARE ARRANGEMENT 3.011493 12mm Fletcher 102/375 x Inventor: Charles J Litz, J C n n, 3,791,299 2/l974 Simmons lO2/35.4

, r [73] Assignee: The United States of America as lnmary hxammer R0hul sta'hl represented by the Secretary of the Army, Washington, DC. ABSTRACT [22] Filed: Nov. 23, 1973 An aircraft self-sustaining flare that provides a refer- [21] Appl' 418798 ence source of illumination, operating at a constant altitude and being relatively insensitive to wind drift. [52] U.S. Cl l02/35.4, 102/35.6, 102/371, Th flare arrangement employs a whirling rotor blade 102/375, 102/377 structure that is driven by pressure gas produced by a [51] Int. Cl C06d 1/04, F42b 13/40 g g n r mounted in he c ntral portion of a [58] Field of Search 102/35, 352, 354, 35 6, combustible flare tube intermediate a pair of longitul02/37.l, 37.5, 37.7, 37,8 dinally spaced cylindrical flare propellant grains Electrical ignition means ignite the gas generator and the [56] References Cit d end surfaces of the flare propellant grains.

UNITED STATES PATENTS 6 C 1 D 2,044,024 6/1936 Wiley 102/350 x rawmg PATENTED JANZ] [975 mm m FLARE ARRANGEMENT The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to flares, and more particularly to an aircraft self-sustaining flare.

Prior aircraft flares for battlefield illumination and the like utilized spherical balloons or parachutes but have not been entirely satisfactory because excessive wind drift moved the flares off their designated illumination target.

One of the objects of the invention is to provide an aircraft flare which is insensitive to wind drift.

Another object of the invention is to provide such a flare that provides a reference source of illumination.

A further object of the invention is to provide such a flare that has the capability of functioning at a constant altitude.

A further object of the invention is to provide such a flare arrangement which has minimum weight and number of moving parts.

These and other objects, features and advantages will become more apparent from the following description and accompanying drawing which is a longitudinal sectional view, partially broken away, of a preferred aircraft flare embodying the principles of the invention.

The combustible flare tube of meltable plastic material or compressed cardboard is substantially cylindrical in shape although a portion of its lateral surface is appropriately recessed the full length thereof as defined partially by the recessed or cavity wall portion 11 to accommodate the diametrically opposed pair of rotor blades 12, 13 in their pre'operational position. An elongated disposable light metallic cover 14, having a snapfitting inwardly directed end flanges 15, 16 for removable securement to the suitably recessed end faces 17, 18 of cavity wall portion 11, overlies the rotor blade arrangement cavity and in its assembled position completes the cylindrical contour of flare tube 10.

A pair of longitudinally spaced support members 20, 21 of lightweight plastic material extend across the tube 10 to define therebetween a central compartment in which is housed and suitably mounted an electrical timer 23 and a gas generator unit 24 that contains an end burning cylindrical solid propellant grain 25. The gas generator cover 26 contains an electric squib igniter 27 for ignition of the grain 25 and has a laterally extending cylindrically shaped piston cup 28 threadedly and sealingly secured thereto. Slidably and rotatably mounted in cup 28 is a hollow piston rod 29, the inner apertured flange portion 30 of which is responsive to pressure gas developed by the propellant grain 25 and the outer end portion 31 of which pre-operationally seats in an appropriate recess in the cover 14 which is ejected thereby upon outward movement of hollow piston member 29. The piston rod outer end 31 has diametrically opposed bifurcated flange portions 32, 33 carrying corresponding pin members 34, 35 by which the respective rotor blades 12, 13 are pivotally mounted for movement to their inclined operative positions (shown in phantom) after cover 14 has been ejected.

A pair of hollow brass ducts or connectors 36, 36, threadedly secured by their corresponding threaded end portions 37 to diametrically opposed tapped

holes

38, 38 and by respective threaded end portions 39 to corresponding tapped openings 40, 41 in the hollow rotor blades, each have a flexible center portion 42 which accommodate the operative blade pivotal motion. The flexible ducts 36 respectively place the hollow piston rod interior in fluid communication with the tubular passages 44 within rotor blades 12, 13 and their terminal exit nozzles 45 that each exhaust on the trailing edge of the blade adjacent its tip.

The opposite ends of the tube 10 each contain one of a pair of longitudinally spaced flare propellant grains 50, that are substantially cylindrical in shape (suitably slotted to accommodate cavity wall 11) and appropriately cemented in position. Each grain 50 has a central longitudinal passage 51 in which is positioned respective combustible tubular members 52, 53 of meltable plastic material or compressed cardboard that house corresponding wire portions 54, 55 of electric wiring 59 that extend from the respective electric squib primary ignites 56, 57 cemented in flare grain end recesses to suitable connections within electrical timer 23 through internal passages 58 in support disc members 20, 21. Cemented to the outer end surface of each flare grain 50 is a centrally apertured secondary igniter disc 60 which extend across the interior of tube 10 adjacent a respective end thereof. End cap 61 has its forward surface suitably recessed to define a forwardly extending annular ring 62, a portion of which on assembly slidingly fits over the rearmost lateral surface of flare tube 10 and mating cover 14. The rearward surface of end cap 61 has an appropriate recess 63 that defines the rearward surface 64 which receives the launch gas pressure upon launching of the flare tube 10 from an aircraft, preferably a helicopter. The forwardmost lateral surfaces of the flare tube 10 and mating cover 14 have a suitably shaped annular or peripheral recess to receive the snap-like engaging inner end 66 of the aerodynamic nose cone 67. Preferably, a trio of collapsed aerodynamic stabilization fins 70 are pivotally mounted on a corresponding pin 71 mounted in appropriate respective longitudinally extending recesses provided in 'a rearward lateral surface of flare tube 10 and peripherally spaced at substantially from each other. Each aerodynamic fin or flap 70 is moved or pivoted from a nonprotruding position outwardly to its operative protruding position by a suitable compression spring 72 upon launching of the flare unit from the aircraft.

The electric wiring 59A connects electric squib igniter 27 with appropriate contact means (not shown) within electric timer 23 which is arranged after a predetermined launch period to sequentially ignite the squib igniters 56, 57 prior to ignition of squib 27. Upon sequential ignition of the

secondary igniters

60, 60 and gas generator propellant grain 25., the generated pressure gas at the end burning surfaces of

grains

50, 50 and grain 25 assure removal of end cap 61 and nose cone 67 prior to the lateral movement of piston rod 29 to eject the cover 14 and move the rotor arrangement laterally away from recess wall 11. Of course, where there has been a flare tube launch in a substantially horizontal direction relative to the ground or terrain, such rotor movement axially of its shaft 29 will elevate the rotor relative to the ground. Subsequent pressure gas delivered through the hollow shaft or piston rod 29, flexible ducts 36, 36 will exit

rotor blade nozzles

45, 45 to rotate the blades 12, 13 and its hollow piston rod 29 to sustain the end burning flare arrangement at a predetermined elevation and position depending on the output of gas generator 24. Upon rotation of rotor blades l2, 13 they will incline slightly (as shown in phantom) about their pivot pins 34, 35 to limits as controlled by means not shown.

Various modifications, changes or alterations may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A self sustaining flare arrangement for illuminating a predetermined area from a substantially constant elevation thereabove, comprising a combustible flare tube housing a pair of longitudinally spaced cylindrical flare propellant grains and a central gas generator unit therebetween, each of said flare grains having an outer end surface containing an igniter, said unit housing a gas generating propellant and an igniter therefor,

an elongated disposable cover removably secured to a peripheral surface portion of said tube,

a plurality of hollow rotatable blades underlying said cover and secured to a laterally extending piston rod,

said piston rod having an outer end portion in alignment with said cover, an inner flange portion and an intermediate hollow portion slidably and rotatably mounted in said gas generator unit, said hollow and flange portions being in fluid communication with said gas generator,

a plurality of flexible ducts fluidly communicating a corresponding hollow blade with said hollow piston portion, and

means for electrically initiating said gas generating igniter and each of said flare grain igniters to burn said flare grains, eject said cover, and extend and rotate said blades and piston rod.

2. The structure in accordance with claim 1 wherein each of said blades has an exit nozzle adjacent the tip of the respective blade and in fluid communication with a corresponding one of said ducts.

3. The structure according to claim 2 wherein each of said flare grains has a central longitudinal passage, said electrically initiating means includes a pair of wire portions, and a pair of combustible tubular members respectively housing a corresponding one of said pair of wire portions and positioned within and extending substantially the full length of a corresponding one of said central longitudinal passages.

4. The structure of claim 3 wherein each of said flare grain igniters includes a secondary igniter disc cemented on the respective grain outer end surface and an electrical squib primary igniter cemented in a central recess adjacent the corresponding central longitudinal passage.

5. The structure of claim 4 wherein an end cap is slidably mounted on one end of said combustible flare tube, and a nose cone is removably secured to the other end of said flare tube.

6. The structure of claim 5 wherein the rearward lateral surface of said flare tube has a plurality of pivotally mounted fins.

Claims

1. A self sustaining flare arrangement for illuminating a predetermined area from a substantially constant elevation thereabove, comprising a combustible flare tube housing a pair of longitudinally spaced cylindrical flare propellant grains and a central gas generator unit therebetween, each of said flare grains having an outer end surface containing an igniter, said unit housing a gas generating propellant and an igniter therefor, an elongated disposable cover removably secured to a peripheral surface portion of said tube, a plurality of hollow rotatable blades underlying said cover and secured to a laterally extending piston rod, said piston rod having an outer end portion in alignment with said cover, an inner flange portion and an intermediate hollow portion slidably and rotatably mounted in said gas generator unit, said hollow and flange portions being in fluid communication with said gas generator, a plurality of flexible ducts fluidly communicating a corresponding hollow blade with said hollow piston portion, and means for electrically initiating said gas generating igniter and each of said flare grain igniters to burn said flare grains, eject said cover, and extend and rotate said blades and piston rod.