FR2675250A1 - METHOD AND DEVICE FOR DETERMINING THE EFFECTIVE FLIGHT SPEED OF MISSILES. - Google Patents

Abstract

The invention relates to a method and a device for determining the distance and / or the effective flight speed of a missile (1) guided by a wire or by an optical fiber (5). A spool (3) from which the wire or optical fiber (5) is unwound during flight, is mounted at the end of the missile (1). A sensor (8, 9) disposed in the output region of the wire (5) counts the number of unwound turns of wire and transmits the information to an evaluation unit (11) which determines, from them, the distance and speed of flight.

Description

i Method and device for determining the effective flight speed of

missiles

  The invention relates to a method for determining the

  tance and / or effective flight speed of a missile guided by wire or by optical fiber, inside which is disposed a fixed coil from which the wire or optical fiber is unwound during the flight,

  as well as devices for implementing said method.

  It is advantageous, in particular in the case of missiles whose research head is equipped with a camera for taking pictures, of being able

  determine the effective flight speed of the machine The Pitot tubes ha-

  usually used on airplanes are ill-suited to missiles, these Pitot tubes having to be placed at a point where the flow is as little disturbed as possible This solution is difficult to apply

  on missiles; moreover, the expenditure in material for this mode of

  sure the flight speed is relatively important.

  With target-guided missiles, it is integrated

  knowing the distance traveled in order to be able to determine from the value of the angular deviation the effective value of the

  deviation from the line of sight.

  The objective of the present invention is to propose a relatively simple, but nevertheless precise, means for determining the distance and / or the effective flight speed of a missile guided by

wire or fiber optic.

  The problem is solved according to the invention by the fact that

  on the unwinding of the wire or the optical fiber of the reel In particular

  bind, we measure the number of turns unwound from the optic wire or fiber

  that and the frequency of reeling thereof or thereof.

  According to an alternative solution of the invention, the wire is divided

  or the optical fiber in elements of regular length, we place re-

  fathers on the wire or the optical fiber and we measure the number of landmarks

reeled out per unit of time.

  The device for implementing the method according to the invention

  vention comprises a coil which is fixed by one end of its core to the end of the missile and is coaxial with the longitudinal axis of the missile, which coil is surrounded by a cylindrical casing which comprises at its rear end an annular space by which the

  wire or optical fiber comes out and is unwound by rotational movements

  helical in the annular space, a sensor placed at at least one point in the annular space counting the revolutions of the wire or the

bre optical taking place.

  According to another embodiment of the invention, the coil comprises loop-shaped measurement wires which are arranged at regular distance on the wire or the optical fiber and are torn off one after the other during the unwinding of the wire or fiber optics, which

  measurement wires are connected to an electrical circuit for counting and

  The invention uses on missiles guided by wire or by fiber

  optics the fact that the coiled length of each of the turns of the different

  annealed layers of a coil of wire is known; so we can measure

  by simple means, through the frequency of reeling

  ge, the unwinding speed which corresponds to the actual flight speed.

  The invention is described below using two examples of

  realization partially represented on the des-

  sins These represent: Figure 1, the end of a missile guided by wire or by optical fiber equipped with a measurement device making it possible to determine the frequency of reeling and Figure 2, the end of a missile guided by wire or fiber optic equipped with a device for measuring elements of

  same length of the unrolled wire or optical fiber.

  In the embodiment shown, a coil of wire or optical fiber (simply designated wire in the following) is mounted at the end of a missile 1 which moves in the direction designated by the arrow 2; the wire is used for the transmission of guidance signals and, if necessary, image signals between the missile and a cockpit The coil 3 is fixed by one end 4 1 of the coil core 4 to the missile 1 and is coaxial with the longitudinal axis 1 1 thereof The wire whose rear end is fixedly connected to the fire control station not shown is unwound from the reel 3 during flight

  and has a helical rotational movement around the bobbin casing

  ne 3 and the core 4 The coil 3 is surrounded by a coil cover 6

  cylindrical, the front end of which is connected directly to the missi-

  the 1 while the rear end forms with the coil 3 or the ex-

  end 4 2 of the coil core 4 an annular space 7 through which the wire 5 is drawn during the flight, the wire forming circles

in said space 7.

  A light barrier 10 formed by a laser diode or

  a light emitting diode 8 and a receiving diode 9 is available

  placed at a point in the annular space, which dam records the

  passage of the wire 5 during the unwinding of each turn and transmits the information

  Operation electronics 11 The number of light barrier interruptions per unit of time is thus determined and a correction factor is applied to it which takes account of the fact that the circumference of the turns of the outer layer of the coil East

  larger than that of the coils which are located further inside.

  Knowing the length of the wire in the different turns we can cal-

  calculate the distance and the flight speed directly from this

stantaneous of the missile.

  In the embodiment shown in Figure 2, as

  in that of FIG. 1, a coil of wire 23 is disposed at the end

  tee of a missile 21, the wire 25 being unwound from the coil 23 layer by layer during the flight Each layer of wire 25 is marked at regular distance by means of a thin measuring wire which is wound in the form of

  loop at the corresponding places on the wire 25 inside the box

  bine 23 in such a way that the measuring wire is necessarily back

  when the wire 25 is unwound to the mark concerned The different

  rents measuring wires 30, 31, 32 each constitute a short bridge

  circuit whose cutoff is recorded as a function of time in operating electronics 41 Since the length of the wire 25 between two measurement wires is known, the path traveled is also known The time elapsed between the breakage of two measurement wires East

  inversely proportional to the flight speed of the missile.

Claims (4)

  1 Method for determining the distance and / or the effective flight speed of a missile guided by a wire or by an optical fiber, in which a coil is mounted from which the wire or the optical fiber is unwound during the flight, characterized in that the wire feed or the optical fiber from the reel is measured. 2 Method according to claim 1, characterized in that the number of turns of the wire or of the optical fiber is measured and the   frequency of unwinding it or this.   3 Method according to claim 1, characterized in that, inside the coil, the wire or the optical fiber is divided into elements of regular length and marks are placed on it or it and   in that we measure the number of marks unwound per unit of time.   4 Device for implementing the method according to the   vendication 1 or 2, characterized in that the coil (3) is fixed by   one end (4 1) of the core (4) at the end of the missile (1) and is co-   axial with the longitudinal axis (1 1) of the missile, in that the coil (3) is surrounded by a cylindrical casing (6) which has at its rear end an annular space (7) through which the thread or the fiber optic (5) comes out and is unwound by helical rotational movements in the annular space (7) and in that a sensor (8, 9) is placed in a   point at least in the annular space (7), which sensor counts the   changes in the unwinding thread or optical fiber (5).   Device for implementing the method according to claim 1 or 3, characterized in that the coil (23) comprises measuring wires (30, 31, 32,) in the form of a loop which are arranged at regular distance on the wire or the optical fiber (25) and are torn off one after the other during the unwinding of the wire or the optical fiber (25), which measurement wires are connected to an electrical counting circuit and operating (41).