Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F41—WEAPONS
  • F41G—WEAPON SIGHTS; AIMING
  • F41G3/00—Aiming or laying means
  • F41G3/14—Indirect aiming means
  • F41G3/142—Indirect aiming means based on observation of a first shoot; using a simulated shoot

Definitions

• the present invention relates to a method for correcting the trajectory of a projectile of a gun, a mortar or a rocket launcher or the like firearm, said method compris ⁇ ing a step of determining the site coordinates of a firing position and a recognized target on a map, and of using a compass, an azimuth gyro or some other method for deter- mining the bearing from the firing position to the target at the accuracy of a few degrees. More specifically, the invention is about the speedy adjustment of bearing and elevation of the barrel of a gun for high-precision firing .
• the projectile When firing a gun, a mortar and a rocket launcher or the like firearm to far-away targets, the projectile will reach a very high altitude at the highest point of its trajectory, even an altitude of up to 5 - 15 km.
• the climatic disturbances have a major effect on target-hit- ting precision.
• the force and direction of wind may vary at various altitudes.
• the air density and atmospheric humidity may vary substantially at various altitudes.
• the method involves two inaccuracy factors.
• the weather probe is exposed to winds and, hence, during the ascent, it may drift even far away from the location of the projectile trajectory.
• the calculation effected with the layer formula only provides an approxi ⁇ mation for the required correction. Attempts have been made to correct the positional inaccuracy by dropping the weather probe from an aircraft. This possibility is not always available.
• the determination of eleva- tion also requires a temperature correction of gunpowder, since the rate of combustion of gunpowder and the muzzle velocity of a projectile are dependent on the temperature of gunpowder. Taking all the corrections into consider ⁇ ation requires a substantial calculating power and accord- ingly expensive equipment, if the calculation is to be performed within a reasonable time frame.
• An object of the invention is to provide an improved method for determining the required correction for dis- placement and elevation of the barrel or tube of a gun, a mortar or a rocket launcher by simultaneously accounting for all firing-related disturbance factors so as to achieve a target-hitting precision better than before.
• Another object of the invention is to speed up the calcu- lation of required correction and the transfer to a new firing position.
• fig. 1 is a schematic overhead view of the operating principle for a method of the invention.
• figs. 2a and 2b show alternative embodiments for details associated with one stage in a method of the invention.
• a gun 1 has been driven to a firing position 2 which has fixed its position accurately e.g. by means of spotting signals received thereby from a GPS- system 6, 7.
• the reconnaissance has cleared the site coordinates of a target 4 on the map at an accuracy which is sufficient for a projectile finding said coordinates to destroy the target 4.
• a compass utilizing the magnetic field of the earth e.g. a flux gate compass
• an azimuth gyro or some other method is used for determining the bearing from the firing posi ⁇ tion 2 to the target 4 at an accuracy of a few degrees .
• An indicator projectile 5 is fired intentionally a few degrees off the target 4 and the elevation is determined such that with standard atmosphere a strike is made at a point P the same distance away as the target 4. If the wind action is e.g. from the direction of an arrow A, the bearing and flying distance of an indicator pro j ectile differ from hypothetical values based on standard atmo- sphere in such a manner that the indicator projectile falls on the point P.
• the flying characteristics of the indicator projectile 5, such as weight, shape, and rota- tive moments relative to various axes, correspond to those of a real explosive projectile.
• the indicator projectile 5 is fitted with an electronic package 8, which contains a receiver for picking up positioning signals from an external spotting system, e.g. a GPS-system 6, 7 conventional electronic elements for fixing a position on the basis of received signals - a transmitter for sending the site coordinates with a properly ciphered digital radio signal to a receiver unit 3 in the firing position.
• an external spotting system e.g. a GPS-system 6, 7 conventional electronic elements for fixing a position on the basis of received signals - a transmitter for sending the site coordinates with a properly ciphered digital radio signal to a receiver unit 3 in the firing position.
• the corrections for elevation and bearing can be made easily on the basis of a difference between the coordinates of a hypothetical location P 1 and a real location P 2 of the indicator projectile.
• the indicator projectile 5 is fired sufficiently off the target 4 not to be observed in the target area, the indicator projectile must nevertheless travel in substantially the same weather conditions over substan- tially the same distance as the actual live projectile to the target 4. Thus, all firing-related disturbance factors can be taken into consideration at the same time. This applies also to the temperature of gunpowder, which will be automatically accounted for as the indicator projectile corresponding to the actual explosive projectile in terms of its dimensions and weight is stored at the same temper ⁇ ature as live ammunition.
• the spotting system may be a spotting system based on fixed ground stations or a GPS-system or a differential
• GPS-system wherein the inaccuracy intentionally added in satellite spotting 6 is eliminated by means of a ground
• the spotting accuracy can be increased according to the invention in such a manner that, in the receiving unit 3 of a firing position, whose site coordinates are precisely known, the spotting is performed simultaneously with the spotting of an indicator projectile by receiving a spotting signal of the GPS-satellites 6 and by comparing the spotting result with the precisely known site coordinates of the firing position 2, 3.
• This comparison results in the discovery of a position error caused by the fading of system coordi ⁇ nates, whereby a correction equal to said error can be made in the site coordinates received from the indicator projectile 5.
• Fig. 2a illustrates how the electronic unit 8 containing a transmitter and a receiver can be launched or e jected from the indicator projectile 5 rearwards to a substantially stationary position before tne indicator projectile 5 hits the ground.
• Technology for discovering the proper instant is used e.g. in mid-air exploding ammunition.
• the indicator projectile 5 or the electron ⁇ ic unit 8 released therefrom can be decelerated with a parachute 9 prior to hitting the ground, as shown in fig. 2b.
• the arrangements shown in figs. 2a and 2b are used to make sure that the electronic unit 8 does not sink too deep in the ground or disintegrate in case the indicator projec- tile 5 hits a rock or a stone.
• the release of the electronic unit 8 from the projectile can also be effected on the basis of flying time, in other words the electronic unit has its clock activated during the muzzle acceleration of a projectile and the electronic unit is released after a preset time.
• the electronic unit 8 can be incorporated also in explod ⁇ ing projectiles so as to receive coordinates from all strikes .
• the information supplied by the electronic unit 8 may also include a measured flying time, which can be utilized in fire control calculations.
• the information provided by the electronic unit 8 can also be utilized, such that the received information is used for calculating the corrections necessitated by weather, Coriolis effect, change of gravity (according to lati ⁇ tude), gunpowder temperature and muzzle velocity for conventional fire control calculation.
• the electronic unit 8 can be made self-destructive after it has transmitted site coordinates for its own location. The purpose of this is to avoid revelation of the applied technology.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8546245

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (5)

• 1996
  • 1996-06-19 FI FI962545A patent/FI98957C/fi active IP Right Grant
• 1997
  • 1997-06-19 WO PCT/FI1997/000397 patent/WO1997048963A1/en active IP Right Grant
  • 1997-06-19 DE DE69717488T patent/DE69717488T2/de not_active Expired - Fee Related
  • 1997-06-19 EP EP97927216A patent/EP0939881B1/en not_active Expired - Lifetime

Patent Citations (5)

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