Measuring and testing – Speed – velocity – or acceleration – Acceleration determination utilizing inertial element
Patent
1997-06-27
2000-03-28
Williams, Hezron
Measuring and testing
Speed, velocity, or acceleration
Acceleration determination utilizing inertial element
244 321, 367124, 367906, G01S 300, G01S 1100, F41G 700
Patent
active
060416548
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and a device for determining the roll angular position of an aerial towed hit detector, where the determination is in particular to be used when towing targets of type non-rigid targets such as sleeve targets.
DESCRIPTION OF THE RELATED ART
When indicating the positions of hits in test firing at aerial towed targets, for example of type sleeve targets, conventionally a hit detector is used, that can be suspended in principle in a cable between the towing aircraft and the target. However, such a hit detector has a not quite stable position, in particular a not stable angular position, but can obtain an oscillating or swinging movement in the roll angular direction or laterally because of the aerodynamic instability of many targets, for example targets made of loose flexible sheet material such as a sleeve target. When making an indication by means of the hit detector various calculation routines are used, which are performed automatically and in which generally the position of the hit indicator is assumed to be known, so that it in many cases is assumed to have for example the same orientation, that is that some reference line in the indicator is located in a vertical plane. However, because of the oscillatory movement of the hit indicator errors will then be introduced in the calculation. It will become particularly observable in the case where hit indicators are made with a high accuracy such as is commonly used nowadays, for example for hit detectors providing an indication within one of twelve possible angular sectors.
In U.S. Pat. No. 5,247,488 a sensor ring 1 is disclosed comprising at least three acoustical detectors 2.1-2.8. The ring is assumed to be attached to the body of a towed target, for the case of "tow-target bags the sensor ring may be part of the wall of the front side electronic cylinder" (col. 3, lines 25-28). Such a ring has no preferred angular position or orientation since the tow target can rotate about a longitudinal axis. For ascertaining the rotational position of the sensor ring with respect to the vertical line a vertical sensor 8 is arranged in a fixed connection to the sensor ring 1 (claim 6). The vertical sensor 8 consists of a mass pendulum 9 and an absolute-angle sensor 10 on a mounting rod 11 extending along a diameter of the sensor ring 1 (col. 2, lines 29-31 and FIG. 1). The signal provided by the absolute-angle sensor 10 is used in calculations of the shot angle.
In the International patent applications having publ. Nos. WO-A1 79/00452 and WO-A1 91/10876 methods and devices are disclosed having arrays of acoustical sensors which would greatly benefit from information on the angular position of the sensor arrays. However, no such orientation sensor means are described in these applications and no hint is given that the provision of such a sensor would favour the calculations that are performed for indicating various hit parameters.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method and a device for improving the accuracy when indicating various hit parameters, such as miss distance, by means of hit detectors.
It is another object of the invention to provide a method and a device for determining the position of a hit detector that is towed by an aircraft, whereby an increased accuracy can be obtained when indicating hit parameters in relation to an aerial towed target.
Thus generally, one or more hit parameters are determined for a projectile passing in the vicinity of a target. The hit parameters can be miss distance, path or direction of the projectile, etc. The target is provided with some type of hit indicator or hit detector and this senses in the conventional way shock waves generated by the projectile passing through the air. Based on the detected shock waves, calculations are performed for determining the hit parameters. The position of the hit indicator is determined by position determining means all the time or at least at those instances when the shock waves
REFERENCES:
patent: 4899956 (1990-02-01), King et al.
patent: 5247488 (1993-09-01), Borberg et al.
Air Target Sweden AB
Kwok Helen C.
Williams Hezron
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