Aeronautics and astronautics – Missile stabilization or trajectory control – Externally mounted stabilizing appendage
Reexamination Certificate
2000-04-12
2001-12-04
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Missile stabilization or trajectory control
Externally mounted stabilizing appendage
C244S113000, C244S003260, C244S003290
Reexamination Certificate
active
06325325
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to devices for translational braking of a projectile on its trajectory.
Such devices are known, particularly in the field of artillery. EP138942 describes an artillery projectile which comprises a device for braking a warhead whose deployment is controlled on the trajectory.
Such a device makes it possible to improve the accuracy of artillery firing, taking into account the scatter due to variations in the initial velocity of the projectile. It is thus possible to aim the weapon so as to fire further than the target in sight; a fire control measures the true velocity of the projectile at the muzzle of the weapon barrel and a braking order is then transmitted to the projectile in order to reduce its range and bring it to the desired impact point.
The braking device described by this patent comprises either radially mobile ratchets or a flat frontal surface. Compared to the projectile cross section, the surface of these braking means is too small to give them sufficient braking capacity.
Patent WO98/01719 describes another braking device for projectiles. The device comprises four air brake plates stacked on each other and mobile radially with respect to the projectile. The braking surface is thus greatly increased (it constitutes approximately double the projectile cross section) with a reduced bulk inside the projectile body. This device, however, entails drawbacks.
The shapes of the plates are complicated when it comes to machining them; they also involve numerous notches that reduce their mechanical strength, especially when they are in their totally deployed position, which is the position where the stresses are at a maximum. Moreover, each plate is guided by the cooperation of pins integral with the ends of arms on the plate and which cooperate in the notches of a neighboring plate as well as a base plate. The arms have some flexibility, which impairs the reliability of the guidance function. This entails the risk of jamming and this risk is further increased by the fact that there is double guidance (on a neighboring plate and on a base plate). Finally, the plates are unlocked by means of two gas generators that move two retaining pins with each pin immobilizing two plates. Such a structure is liable to cause dissymmetries or jamming at the moment the plates are deployed; this, in turn, entails the risk of altering the projectile trajectory in a nonreproducible fashion.
SUMMARY OF THE INVENTION
The object of the invention is to propose a translational braking device for a projectile that does not present these drawbacks.
The braking device according to the invention is based on a simple and low-cost design; it offers improved mechanical strength when compared to the previously described device. It has low susceptibility to jamming and this results in a perfect air brake opening symmetry.
The invention thus relates to a translational braking device for a projectile on its trajectory; it comprises at least two radially deployable air brakes so as to increase the aerodynamic drag of the projectile; the air brakes are made in the form of flaps that move in a plane perpendicular to the axis of the projectile; the device is characterized in that each flap has at least two closed grooves extending essentially parallel to a direction that is perpendicular to the axis of the projectile, each groove cooperating with a rod that is fixed with respect to the projectile. Each rod advantageously could cooperate with two grooves of two adjacent flaps. The device could comprise at least one pyrotechnic piston, providing for the locking of at least one of the flaps when in the folded position.
According to a particular embodiment, at least two of the flaps are stacked on each other when they are in their folded position with at least a first of the two flaps comprising means that keeps the second of the two flaps in the folded position.
According to another embodiment, the braking device comprises at least three flaps, a first flap being locked by the pyrotechnic piston and having a first notch, cooperating with a first pin borne by a second flap to keep the latter in the folded position, while the second flap bears a second notch, cooperating with a second pin borne by a third flap to keep the latter in the folded position with a single pyrotechnic piston, thus locking all of the three flaps. Each flap can have an external structural shape covering an arc of a circle whose diameter is essentially equal to the diameter of an external portion of the projectile, and a notch, designed to make it possible to place the flap in the folded position around an axial support integral with the projectile. The axial support could bear two plates, one lower plate and one upper plate, connected by the rods, while the flaps are disposed between the two plates when they are in the folded position.
According to another particular embodiment, at least one groove in each flap could have means for slowing down the deployment movement of the flap. Means for slowing down the deployment movement could advantageously comprise a particular shape of the groove and/or a particular shape of the notch with the groove and/or the notch having at least one indentation. The flaps could also be generally integral with a nose fuze of the projectile.
REFERENCES:
patent: 2840326 (1958-06-01), Richardson et al.
patent: 3188958 (1965-06-01), Burke et al.
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: 21 04 914 A (1972-08-01), None
patent: 0 138 942 B1 (1985-05-01), None
patent: 2 071 271 A (1971-09-01), None
patent: WO 98/01719 (1998-01-01), None
Bonnet Alain
Cros Anne-Laure
Padiolleau Bertrand
Dinh Tian
Giat Industries
Jordan Charles T.
Oliff & Berridg,e PLC
LandOfFree
Device for translational braking of a projectile on its... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for translational braking of a projectile on its..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for translational braking of a projectile on its... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2572016