Measuring in-situ MDF velocity of detonation
A system for determining the velocity of detonation of a mild detonation fuse mounted on the surface of a device includes placing the device in a predetermined position with respect to an apparatus that carries a couple of sensors that sense the passage of a detonation wave at first and second spaced locations along the fuse. The sensors operate a timer and the time and distance between the locations is used to determine the velocity of detonation. The sensors are preferably electrical contacts that are held spaced from but close to the fuse such that expansion of the fuse caused by detonation causes the fuse to touch the contact, causing an electrical signal to actuate the timer.
1. A method of determining velocity of detonation of a metal-clad explosive fuze that expands in diameter as it detonates along its length, comprising:
placing a sensor spaced from and adjacent a first location on the fuze;
placing a second sensor spaced from and adjacent a second location on the fuze;
igniting the fuze at a third location on the fuze, wherein the fuze detonates along its length past the first and second locations, the expanded fuze being detected by each sensor as the fuze detonates at that sensor's location; and
determining the velocity of detonation from the time difference between the actuation of each sensor;
wherein the sensors are mounted on an apparatus and the fuze is in a groove on a device, wherein the placing steps comprise:
holding the apparatus against the device in a fixed position with the first and second sensors vertically aligned with the respective first and second locations;
moving each sensor toward the fuze until it contacts the fuze; and
moving each sensor to a sensing position that does not contact the fuze before detonation, and that will be contacted by the detonated fuze.
2. The method of claim 1 wherein the third location is not between the first and second locations.
3. The method of claim 2 wherein the ignited fuze actuates the first sensor before it actuates the second sensor.
4. The method of claim 3 wherein each sensor comprises an electrical conductor that contacts the fuze only after the fuze expands from detonation at the sensor.
5. The method of claim 4 further comprising an electrical circuit connected to each conductor, wherein actuation of each sensor causes a voltage change in the electrical circuit connected to that sensor.
6. The method of claim 1 wherein each sensor is a screw that extends through a block that covers the first and second locations, and the sensors are moved by screwing them towards and away from the fuze.
7. An apparatus for measuring the velocity of detonation in a mild detonation fuze extending in a groove on the surface of a device, the device including an igniter at one end of the fuze, said apparatus comprising:
a first sensor spaced from and adjacent a first location on the fuze;
a second sensor spaced from and adjacent a second location on the fuze, the second location being further along the fuze from the ignition end than the first location, said first and second sensors being spaced sufficiently close to the fuze that detonation at a sensor location is detected by the respective sensor;
registration structures operatively arranged to precisely position said first and second sensors with respect to the first and second locations, respectively; and
a timer that is started when said first sensor detects an expanded fuze and is stopped when said second sensor detects an expanded fuze; wherein the velocity of detonation is calculated from time measured by said timer and the known distance between said first and second sensors.
8. The apparatus of claim 7 , wherein said first and second sensors are electrical conductors that contact the fuze only after the fuze expands from detonation at the sensor.
9. The apparatus of claim 8 , wherein said first and second sensors are screws retrievably extendible and electrically conducting and having tips pointing towards the first and second locations, respectively.
10. A method of determining velocity of detonation of a metal-clad explosive fuze, which expands in diameter as it detonates along its length, the method comprising:
placing a first sensor on a first module, wherein the first sensor is spaced from and adjacent a first location on the fuze, and wherein the fuze is placed on a second module;
placing a second sensor on the first module, wherein the second sensor is spaced from and adjacent a second location on the fuze;
positioning precisely the first and second sensors with respect to the first and second locations, respectively, using registration structures on the first module;
igniting the fuze at a third location on the fuze, wherein the fuze detonates along its length past the first and second locations, the expanded fuze being detected by the first and second sensors as the fuze detonates at that sensor's location; and
determining the velocity of detonation from the time difference between the actuation of the first and second sensors.
11. The method of claim 10 wherein the third location is not between the first and second locations.
12. The method of claim 10 wherein the ignited fuze actuates the first sensor before it actuates the second sensor.
13. The method of claim 10 wherein the first and second sensors are electrical conductors that contact the fuze only after the fuze expands from detonation at the sensor.
14. The method of claim 10 wherein the first and second sensors are screws retrievably extendible and electrically conducting and having tips pointing towards the first and second locations, respectively.