Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Patent
1986-07-24
1987-10-27
Jordan, Charles T.
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
244 326, F42B 1332
Patent
active
047024364
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a guide mechanism for projectiles of the kind which are fired from a barrel with the aid of a propellant charge, the guide mechanism including a plurality of elongated fins which are journalled at one end thereof and which are held in a folded position during passage of the projectile through the barrel and are arranged to be extended by means of a finextending force delivered by a piston arranged for movement in a guide-mechanism housing while in dogging engagement with the fins, and which mechanism further comprises channel means through which propellant gases are delivered to a chamber located on one side of the piston during a pressure increase phase of the propellant gases in the barrel.
BACKGROUND PRIOR ART
Guide mechanisms of the aforesaid kind are known to the art from, for example, German Patent Specification DE No. 960 882. It has been found, however, that with this known mechanism the fins are often extended much too slowly, resulting in insufficient muzzle stability of the projectile. The tail of the projectile is namely still influenced by the pressure exerted by the propellant gases (powder gases) even when the guide surfaces of the projectile have left the muzzle of the barrel, and uneven loads on the fins can therewith cause pronounced wobble or yaw of the projectile in the vicinity of said muzzle, resulting in impaired external ballistics and impaired precision. This problem is particularly difficult to overcome in the case of dart shaped or sweepback projectiles.
DISCLOSURE OF THE INVENTION
Consequently, the object of the invention is to provide a guide mechanism of the aforementioned kind with which the fins are extended more rapidly than with guide mechanisms known hitherto. The invention relates particularly, but not exclusively, to the provision of such a guide mechanism in which the fin-extending force is able to act on the fins before the projectile has reached the nozzle of the barrel, thereby enabling the fins to stabilize the projectile during the actual passage of the projectile through the barrel.
This object is achieved with a guide mechanism constructed in accordance with the invention and having the characteristic features set forth in the characterizing clause of claim 1.
Further developments of the invention are disclosed in the depending claims.
As a result of throttling the channel means in the guide mechanism during the pressure reduction stage, the level of the working pressure is increased and the time taken to evacuate the chamber prolonged. This causes the fins to be extended much more quickly than was previously the case, and makes possible, inter alia, the aforesaid early fin-stabilization of the projectile during its passage through the barrel.
This latter possibility of particular importance when firing with modern lightweight barrels constructed in accordance with wound-glassfibre techniques. Such firing barrels have a large radial stretch, i.e. large clearance, and hence poor precision can be expected. This problem can now be solved in accordance with the invention due to the fact that when necessary (primarily, but not exclusively, in the case of dart-like projectiles) the fins can be caused to extend outwardly prior to the guide mechanism reaching the muzzle of the barrel. The fins are thereby urged against the barrel wall and stabilize the rear part of the projectile during its travel through the barrel.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail with reference to the accompanying drawing, which schematically illustrates a preferred embodiment of the invention.
FIG. 1 illustrates the guide mechanism during the pressure increase phase, whereas
FIG. 2 illustrates the guide mechanism during the pressure reduction phase.
DESCRIPTION OF A PREFERRED EMBODIMENT
FIG. 1 illustrates the rear section 1 of a projectile 2, for example a conventional dart-shaped or sweepback projectile. The projectile 2 is mounted in a conventional manner in a cartridge or shell (not sh
REFERENCES:
patent: 2821924 (1958-02-01), Hansen et al.
patent: 3053184 (1962-09-01), Francois
patent: 3086467 (1963-04-01), Gallagher et al.
patent: 3098446 (1963-07-01), Jasse
patent: 3196793 (1965-07-01), Milenkovic et al.
patent: 3289587 (1966-12-01), Donnelly et al.
patent: 3944168 (1976-03-01), Bizien et al.
Affarsverket FFV
Carone Michael J.
Jordan Charles T.
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