MISSILE FLARE

Abstract: A missile includes an annular flare element 18 which is housed between the outer skin of the missile and the propul­ sion nozzle 14. The flare element allows the propulsion efflux to be as fully expanded as possible whilst still providing a large area of flare.

Description: This invention relates to missiles including a pyrotechnic flare. In many missile systems the missile includes a pyrotechnic flare to enable it to be tracked and in a conventional system the flare comprises several solid cylindrical plugs of pyrotechnic material equispaced around the outlet nozzle of the motor. In this arrangement however, the plugs of pyrotechnic material reduce the maximum possible diameter of the outlet nozzle. Particularly in missiles intended to travel at high speeds, it is desirable for the efflux from the nozzle to be as fully expanded as possible to maximise the boost motor performance in terms of total energy for a given mass. U.S. Patent Specification US-A-3680484 discloses a closed-body infra-red radiation emitter in the form of a thin walled toroidal housing spaced radially outwardly from the periphery of the outlet aperture of the propulsion nozzle. The emitter glows without an appreciable emission of gas. U.S. Patent Specification US-A-2926606 discloses a missile having four equispaced propulsion nozzles each having a radially outer cup containing pyrotechnic material. U.S. Patent Specification US-A-298699 discloses a missile having two solid cylindrical flares which are ignited by the exhaust gases from the main propulsion nozzle. According to this invention there is provided a missile including a body, a propulsion motor mounted within said body, a propulsion nozzle located on the longitudinal axis of the missile in a rearward region of the body for exhausting propulsion efflux rearwardly, characterised in that a pyrotechnic flare element of generally annular cross-section is provided within said body and generally surrounds said propulsion nozzle. By this arrangement the flare element generates a large image but allows the outlet area of the missile nozzle to be relatively large. Further aspects will become apparent from the following description which is by way of example only, in which reference will be made to the accompanying drawings, in which: Figure 1 is a section view through the rear portion of a missile incorporating a pyrotechnic flare; Figure 2 is a general perspective view of the flare in the missile, and Figure 3 is a detail section view on part of the igniter assembly of the missile. The missile illustrated is tracked following launch by an auto-tracker tracking a pyrotechnic flare, and includes an expulsion motor of the type described in our published European Application No. 0228781. Referring to the drawings, the missile includes a body 10, four equally spaced chamfered fins 11 adapted to maintain the missile in a state of spin following launch and an expulsion motor 12 releasably attached to the missile by four nylon shear screws (not shown). The missile includes a boost motor 13 and an associated boost outlet nozzle 14 located within a rearward portion of the body 10 and surrounded by the external skin 15 of the missile. The nozzle includes a throat 16 and an outlet aperture 17. In order to extract the maximum amount of energy from the propellant charge contained in the missile motor it is desirable to have as large an aperture as possible so that efflux from the nozzle is as fully expanded as possible. Between the external surface of the nozzle case and the internal surface of the missile skin 15 is a cavity of generally annular cross-section in which a flare element 18 is located. An insulating liner 19 separates the flare pyrotechnic mixture from the missile skin and motor nozzle surfaces during missile flight to protect these from the burning flare material. No separate flare casing is employed, the flare pyrotechnic mixture being inserted directly into the cavity thereby achieving significant weight savings. An end cap 20 is attached to the rear end face and includes two lugs 21 projecting rearwardly. The two lugs 21 constitute parasitic igniters, including a right angled passage containing a length of igniter cord 22 having one end adjacent the outlet aperture of the boost motor nozzle and exposed to the boost motor efflux on ignition thereof and the other end adjacent the pyrotechnic material of the flare. On launch of the missile, the expulsion motor carries the missile a safe distance away from the launch site, and the boost motor is then ignited. On ignition of the boost motor, the boost efflux jettisons the expulsion motor and ignites the pyrotechnic flare via the parasitic igniters.

Claims: 1. A missile including a body (10), a propulsion motor (13) mounted within said body, a propulsion nozzle (14) located on the longitudinal axis of the missile in a rearward region of the body for exhausting propulsion efflux rearwardly, characterised in that a pyrotechnic flare element (18) of generally annular cross-section is provided within said body and generally surrounds said propulsion nozzle (14). 2. A missile according to Claim 1, wherein said flare element (18) includes igniter means (22) adapted to be ignited by the efflux exhausting through said propulsion nozzle (14). 3. A missile according to Claim 1 or Claim 2, wherein said flare element (18) is formed by packing a pyrotechnic mixture into an annular cavity between the outer surface wall of the missile and the propulsion nozzle (14). 4. A missile according to any preceding claim, wherein said propulsion nozzle is shaped so that in use said propulsion efflux is substantially fully expanded. 5. A missile according to any preceding claim, wherein said flare element is of cylindrical shape.

Inventors: MOATE, RICHARD P. BRIT. AEROSPACE PUB. LTD. CO.
Applicants: BRITISH AEROSPACE PUBLIC LIMITED COMPANY
Application year: 1986
Main classification: F42B12
IPC codes: F42B12