Aeronautics and astronautics – Missile stabilization or trajectory control – Remote control
Reexamination Certificate
1999-08-04
2001-02-13
Gregory, Bernarr E. (Department: 3662)
Aeronautics and astronautics
Missile stabilization or trajectory control
Remote control
C244S003120, C244S003130, C244S003140
Reexamination Certificate
active
06186441
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates an apparatus and a method for determining the point of impact of a ballistic flying body, such as a rocket projectile fired from a gun also referred to as barrelled weapon.
BACKGROUND INFORMATION
The use of ballistic flying bodies such as non-guided rockets or projectiles fired from a gun regains increasing importance. For the precise delivery of a ballistic flying body such as a rovket or a projectile fired for example from an aircraft, it is necessary that the ballistic and the point of impact are ascertained. The impact point is dependent on a multitude of parameters such as attitude, position and motion status of the system from which the ballistic flying body is delivered. Additionally, the impact point is influenced by wind conditions and further characteristic values which relate to the rocket or projectile itself.
Several methods are known for determining the impact point. For example, the determination of the ballistic can be performed in that ballistic coefficients or parameters are determined ahead of time and then stored in the on-board computer of the aircraft in the form of ballistic tables. In accordance with the instantaneous system status a polynomial fit or a direct reading of the table values takes place when the weapon is used.
The above method permits, however, only a mission according to the predetermined coefficients, since the polynomial fit is based on these input values or because a direct reading only yields these values. Additionally, the required memory capacities become very large and even if the data matrix has a fine design only quantified solutions are obtained. Due to the quantified solutions the result is frequently rather imprecise. Moreover, the determination of the coefficients is very expensive. Another disadvantage lies in that the scene of the target must be completely ascertained. When an unforeseen target scene is involved, respective new ballistic tables are required, which calls for a large investment of time for the preparation of the mission.
For example, U.S. Pat. No. 4,494,198 (Smith et al.) discloses a weapons control system with a computer which comprises a first memory with convertible data for the shot distances and a second memory with correction coefficients correlated to different types of ammunition. A ballistic standard range is shown on a display. The standard range is combined with a correction factor in order to provide a corrected ballistic range.
U.S. Pat. No. 4,111,382 (Kissinger et al.) describes an apparatus for controlling a ballistic flying body in which the nominal or rated trajectory is compared with the actual flight parameters which are obtained by an inertia guidance system. A precise ballistic flight is achieved by way of a correction.
In another known method for determining the ballistics and ascertaining the point of impact, a model with three degrees of freedom is established from the actual system parameters. The term “degrees of freedom” as used herein means projectile or rocket intrinsic parameters and firing system parameters in a respective parameters model. Such parameters may include, for example, the mass center of gravity of the projectile, aerodynamic drag of the projectile and so forth. System parameters may include a helicopter downcast parameter, wind parameters and so forth. System parameters may include a helicopter downwash parameter, wind parameters and so forth. It is customary to also refer to these parameters as coefficients. In order to achieve a sufficient precision it is necessary to introduce correction factors at the beginning of the calculation. Particularly for complicated bodies, such as rockets, a multitude of correction factors are required within the model coefficient. The determination of the correction factors is very expensive and permits, just as with the above described method, only a mission based on discrete system states. Especially in connection with a rocket which is fired from a helicopter, larger interfering terms or conditions occur due to the downwash of the rotor. These interfering terms can only be corrected by respective correction factors in the three freedom degree integration model in a quantifying manner.
In order to increase the precision, it has been tried to determine the ballistics and thus the impact point by means of a six-coefficient or parameter model having 6 degrees of freedom. In such a method the flight path and the impact point are determined on the basis of six weapons specific characteristic parameters or coefficients. However, that method is very time consuming and it requires a very high computer capability. As a result, the method leads, on a mission where actual system states are involved, to time delays and thus to substantial imprecisions, especially when used in aircraft, such as combat aircraft or helicopters.
OBJECTS OF THE INVENTION
Thus, it is an object of the present invention to overcome the above discussed disadvantages and to provide an apparatus and a method for the determination of the impact point of a ballistic flying body by means of which it is possible, in different flight states, to rapidly determine the impact point with a high precision.
SUMMARY OF THE INVENTION
The apparatus according to the invention for determining the impact point of a ballistic flying body such as a rocket and/or projectile fired form a firing system such as a rocket launcher or gun comprises at least one memory for flying body specific characteristic values also referred to as first parameters of the ballistic flying body, an evaluating stage which produces control signals in response to the first parameters and in response to actually supplied second parameters representing actual firing system values, an indicator and/or control device which receives the control signals for indicating an impact point determined from the system parameters, and/or for controlling a delivery mechanism whereby a corresponding model of the trajectory of a ballistic flying body is producible in the evaluating stage. The trajectory model is divided at least into two phases each with a submodel, whereby the number of the degrees of freedom or parameters in the first phase is larger or equal to the number of degrees of freedom or parameters in the second phase.
The apparatus of the invention makes it possible to indicate weapons impact point and/or to bring the impact point with an increased precision into coincidence with a target or impact point previously selected without any required quantified provision of discrete parameters in all flight states. A prior calculation of the parameters is obviated, which reduces the expense and permits a mission in all possible scenarios without any expensive preparation. Even where other ballistic flying bodies or weapons are newly introduced, preparation time is being saved, because only the new weapons characteristic values or parameters are required to be stored in the above mentioned memory.
The method according to the invention for determining the impact point of a ballistic flying body comprises the following steps: storing specific, characteristic values or parameters such as mass center of gravity, drag and the like of the ballistic flying body in a memory; transferring actual system parameters, for example attitude and motion status of the delivery system, wind or the like, to an evaluating stage and determining of an impact point; producing of control signals for indication of the impact point and/or for controlling a delivery system for the ballistic flying body; whereby a model of the trajectory of the ballistic flying body to be delivered is produced from the specific, characteristic parameters and from the actual system parameters, said model being divided into at least two phases, each with a submodel; and whereby the number of the degrees of or parameters freedom in the first phase is larger or equal to the number of parameters in the second phase.
The method according to the invention provides the above mentioned advantages and remains unchanged even if
Eurocopter Deutschland GmbH
Fasse W. F.
Fasse W. G.
Gregory Bernarr E.
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