Data processing: measuring – calibrating – or testing – Calibration or correction system – Sensor or transducer
Reexamination Certificate
1999-10-07
2002-11-19
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Sensor or transducer
C702S041000, C702S079000, C702S085000, C702S108000, C702S142000, C702S189000
Reexamination Certificate
active
06484115
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for correcting the pre-programmed initiation of an event in a spin-stabilized projectile, a device for executing the method, and a use of the device.
REVIEW OF RELATED TECHNOLOGY
Methods and devices of this type are used in connection with the chronologically pre-programmed initiation of functions in a spin-stabilized ballistic projectile, wherein initiation of the function is intended to take place at a defined initiation place and therefore at a defined initiation distance from the launch location, or respectively at a defined initiation time, and therefore after a defined length of flight. The function which is to be initiated in this way can be any arbitrary function; with ballistic projectiles the time of disaggregation into partial projectiles, or respectively of fragmentation, is generally determined in this manner.
It has been long known in connection with projectiles of different types, i.e. not only ballistic projectiles, to utilize a time fuse with a fixed or adjustable initiation time for determining the initiation time, wherein projectiles with time fuses with adjustable timing are designated as so-called fuse-time-fixed projectiles.
In principle, two types of time-fixed fuses can be used in spin-stabilized projectiles, namely time fuses and rotary fuses. With time fuses, the disaggregation is initiated at the end of a defined, or respectively definable time interval which, for example, starts at launch; with rotary fuses, disaggregation is initiated after a defined, or respectively definable number of revolutions which the projectile has performed since the launch.
Several methods are known for setting the time fuse, or respectively for the so-called fuse-time-fixing of fuse-time-fixed projectiles. In this case a basic distinction needs to be made between projectiles, wherein fuse-time-fixing takes place in a defined manner prior to launch on the basis of theoretical calculations, and projectiles, wherein fuse-time-fixing takes place after the launch, wherein deviations from theoretically calculated values, for example for the disaggregation location, the disaggregation time, the muzzle velocity or, if required, the final angle of twist, can be taken into consideration. The variation range of one of these parameters, for example of the muzzle velocity or of the final angle of twist, normally lies in a range of less than 5%.
With projectiles which can be fuse-time-fixed during flight, it is possible to provide the fuse with the time of disaggregation by remote signaling, for example. However, such devices have various disadvantages; for one, they require an elaborate implementation of a receiver, and secondly, there is the danger of enemy interference with the remote signaling processes, which can result in incorrect fuse-time-fixation. These disadvantages are so serious that it is therefore often preferred to provide only a pre-programmed fuse-time-fixation, which is not affected anymore during flight, so that no remote signaling connection is required.
Pre-programmed rotary fuses are pre-programmed, preferably during loading, in such a way that ignition takes place after a defined, preset number of revolutions of the projectile. However, without corrective measures, such pre-programming has comparatively inaccurate results, since it cannot take the into consideration deviations, based on the actual flight characteristics of the projectile, from the theoretically determined flight characteristics.
It is known to everyone skilled in the art that the muzzle velocity is an essential value determining the flight characteristics of the projectile. Generally, the effective muzzle velocity deviates for various reasons from the theoretically calculated muzzle velocity, which has the result that the effective location/time of the disaggregation of the projectile differs from the desired location/time of the disaggregation which, for example, had been theoretically determined.
To prevent, or at least limit, such deviations, while still not providing an elaborate remote signaling device, various steps can be taken which are based on detecting the effective frequency of revolutions of the projectile and/or the effective muzzle velocity of the projectile, which is correlated with the effective frequency of revolutions, and including them internally in the projectile in determining the time-fixed fuse time.
Various methods are known for determining the effective muzzle velocity.
For example, the effective muzzle velocity can be detected on the outside of the gun barrel closely near its muzzle by means of a coil arrangement with two spaced-apart measuring coils. However, such measuring coils are comparatively delicate and constitute a particularly endangered component, at least with mobile guns.
The effective muzzle velocity can also be determined by extrapolation from a projectile velocity measured inside the gun barrel in the area of its muzzle cross section. Here, measurement is performed with the aid of two sensors, which are arranged at a defined mutual distance from each other. The disadvantage is that comparatively elaborate devices at the gun barrel are required for executing this method, and that the results are not very accurate as a result of the extrapolation.
In order to avoid the disadvantages of the above mentioned methods for determining the actual muzzle velocity, attempts are also made to determine the actual muzzle velocity of the projectiles after they have been fired, but without additional devices at the gun barrel.
Since there is a fixed connection between the projectile velocity and the frequency of projectile rotation in the flight phase immediately following firing, attempts are made to correlate the time of the disaggregation of the projectile, instead with the projectile velocity, with the corresponding number of revolutions made by the projectile in the course of its flight along its trajectory.
Counting of the rotations of the projectile is performed with the aid of the earth magnetic field in conventional methods of this type. The fuse has a counter, which continuously integrates the number of the projectile revolutions. By means of the spin of the projectile, for example its rotation essentially around the longitudinal axis of the projectile, a voltage is induced inside the fuse, for example in a coil arranged for this, by means of the earth magnetic field, which extends sine-like over time. The counter continuously, i.e. during the complete duration of the flight of the projectile, adds up the number of pulses between two crossovers of this voltage in the same direction. With a fuse which, as mentioned above is called a rotary fuse, ignition, or respectively the disaggregation of the projectile takes place as soon as the number of added-up pulse s has reached a pre-programmed value.
This method has several disadvantages. Counting of the revolutions of the projectile takes place either during its entire time in flight, or only directly following its firing, but with a check afterwards, for example after 80% of the approximate time in flight. Since the voltage induced by the earth magnetic field is only usable if it is amplified, and since energy is needed for this amplification, it is necessary to provide a considerable amount of energy for this amplification because of the comparatively long use of the earth magnetic field Furthermore, interferences with the voltage process induced by the earth magnetic field and of the values derived therefrom can be caused by interfering enemy transmission; the effects of these interferences are the more important, the longer the use of the earth magnetic field lasts.
For example, a multi-functional fuse for spin-stabilized projectiles has become known from EP 0 661 516 A1, wherein the actual muzzle velocity is calculated on the basis of the actual frequency of rotation of the projectile. The earth magnetic field is used for determining the frequency of rotation, wherein each rotation of the projectile provides a pulse. The number of rotations is counte
Freymond Pierre H.
Muenzel Klaus
Browdy and Neimark , P.L.L.C.
Hoff Marc S.
Oerlikon Contraves Pyrotec AG
Tsai Carol S. W.
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