Aeronautics and astronautics – Missile stabilization or trajectory control
Reexamination Certificate
1999-11-30
2001-10-30
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Missile stabilization or trajectory control
C244S003240, C244S003270, C244S003290
Reexamination Certificate
active
06310335
ABSTRACT:
BACKGROUND OF THE INVENTION
The technical scope of the invention is that of translational braking devices for a projectile during its trajectory.
Such devices are notably known in the field of artillery.
Patent EP138942thus describes an artillery projectile that incorporates a device to brake the nose cone whose deployment is controlled during the trajectory.
Such an arrangement allows firing accuracy of artillery fires to be increased whilst taking into account dispersions due to the variations in initial velocity of the projectile. Indeed, it is thus possible to lay the weapon so as to fire beyond the target aimed at, a fire control measures the real velocity of the projectile at the muzzle of the weapon and a braking command is thereafter transmitted to the projectile so as to reduce its range and thus bring it to the desired point of impact.
The braking device described by this patent comprises, either radially mobile fingers, or a plane frontal surface. The surface area of these braking means with respect to the section of the projectile is too small for their braking capacity to be sufficient.
Patent WO98/01719 describes another braking device for a projectile. This device comprises four airbrake plates stacked one on top of the other and radially mobile with respect to the projectile.
The braking area is thus substantially increased (it constitutes approximately double the section of the projectile) and is of a reduced bulk inside the projectile body.
However, this device has drawbacks.
The shapes of the plates are complicated to machine, they also incorporate numerous indents that reduce their mechanical strength, notably in their fully deployed position where the stresses are at their worst.
Moreover, the plates are unlocked by means of two gas generators that displace two retention pins, each pin immobilizing two plates. Such a structure is likely to cause dissymmetries or sticking when the plates are deploying that risk modifying the trajectory of the projectile in a non-reproducible manner.
SUMMARY OF THE INVENTION
The aim of the invention is to propose a translational braking device for a projectile that does not have such drawbacks.
Thus the braking device according to the invention is of a simple inexpensive design and has improved mechanical strength with respect to the previously described device.
It is not likely to stick, and it consequently has perfect opening symmetry of the airbrakes.
Thus, the subject of the invention is a translational braking device for a projectile during its trajectory comprising at least two airbrakes that are radially deployable so as to increase the projectile's aerodynamic drag, wherein each airbrake is a flap pivoting around a pivot integral with the projectile and parallel to its axis.
According to one characteristic of the invention, the braking device incorporates at least one pyrotechnic piston locking at least one of the flaps in its folded position.
According to a first embodiment of the invention, at least two flaps are stacked one on top of the other when they are in their folded position, at least a first of the two flaps incorporating means to retain the second of the two flaps in its folded position.
The braking device can, advantageously, incorporate at least four flaps, a first flap being locked by the pyrotechnic piston and carrying a first pin retaining a second flap in its folded position, a third flap carrying a second pin co-operating with a first retention surface integral with the second flap, a fourth flap carrying a third pin co-operating with a second retention surface integral with the third flap, a single pyrotechnic piston thereby ensuring the locking of all four flaps.
Each flap can have an external profile covering the arc of a circle whose diameter is substantially equal to that of an external part of the projectile and an indent intended to allow the flap to fold around an axial support integral with the projectile.
Each flap can, advantageously, incorporate an abutment heel intended to co-operate with a matching surface of the axial support so as to stop the opening movement of the flap.
The arc length of the external profile of each flap and the length of the different heels can be selected such that, in the deployed position, the free end of at least one flap presses on a neighboring flap or else on the projectile.
The axial supports can carry two plates, a lower plate and an upper plate, each plate supporting at least two pivots of the flaps that are thus arranged between the two plates when they are in the folded position.
According to a second embodiment of the invention, each flap can incorporate a toothed circular portion arranged around the pivot , such portion meshing with a central pinion coaxial to the projectile, such central pinion thereby joining together the different flaps.
The pyrotechnic piston can, advantageously, lock the central pinion.
The flaps can, in any case, be integral with a nose cone fuse of the projectile.
REFERENCES:
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patent: 1300708 (1919-04-01), Edison
patent: 2271280 (1942-01-01), Weinert
patent: 2793591 (1957-05-01), Jasse
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patent: 3768755 (1973-10-01), Prochnow et al.
patent: 3986683 (1976-10-01), Ellison
patent: 4113204 (1978-09-01), Leek
patent: 4856737 (1989-08-01), Zacharin
patent: 5762291 (1998-06-01), Hollis et al.
patent: 5816531 (1998-10-01), Hollis et al.
patent: 5826821 (1998-10-01), Brandon et al.
patent: 0 138 942 B1 (1985-05-01), None
patent: 0 252 036 A2 (1988-01-01), None
patent: 496912 (1919-08-01), None
patent: WO 98/01719 (1998-01-01), None
Bonnet Alain
Cros Anne-Laure
Best Christian M.
Giat Industries
Jordan Charles T.
Oliff & Berridg,e PLC
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