U.S. patent application number 10/315504 was filed with the patent office on 2003-07-31 for medium caliber high explosive dual-purpose projectile with dual function fuze.
This patent application is currently assigned to General Dynamics Ordnance & Tactical Systems, Inc.. Invention is credited to Bone, Frank M..
Application Number | 20030140811 10/315504 |
Document ID | / |
Family ID | 26979938 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030140811 |
Kind Code |
A1 |
Bone, Frank M. |
July 31, 2003 |
Medium caliber high explosive dual-purpose projectile with dual
function fuze
Abstract
A multi-mode fuze for a munition has at least one sensor that
generates an electrical output dependent on a rate of deceleration
when the munition impacts a target, a logic circuit electrically
coupled to the at least one sensor effective to discriminate
between a soft target and a hard target dependent on the electrical
output and a fuze that transmits a detonation signal to an
initiating explosive to thereby detonate the munition. The
detonation signal is transmitted at a time dependent on target
discrimination. The multi-mode fuze of the invention may be
incorporated into an explosive projectile that includes an
aerodynamically shaped metallic casing, an explosive contained
within the metallic casing and an initiating explosive contacting
the explosive. The multi-mode fuze communicates with the initiating
explosive to trigger detonation of the explosive either on impact
with a hard target or following a delay on impact with a soft
target.
Inventors: |
Bone, Frank M.;
(Carterville, IL) |
Correspondence
Address: |
WIGGIN & DANA LLP
ATTENTION: PATENT DOCKETING
ONE CENTURY TOWER, P.O. BOX 1832
NEW HAVEN
CT
06508-1832
US
|
Assignee: |
General Dynamics Ordnance &
Tactical Systems, Inc.
|
Family ID: |
26979938 |
Appl. No.: |
10/315504 |
Filed: |
December 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60341157 |
Dec 14, 2001 |
|
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Current U.S.
Class: |
102/266 |
Current CPC
Class: |
F42C 9/147 20130101 |
Class at
Publication: |
102/266 |
International
Class: |
F42C 009/16 |
Claims
We claim:
1. A multi-mode fuze for a munition, comprising: at least one
sensor that generates an electrical output dependent on a rate of
deceleration when said munition impacts a target; a logic circuit
electrically coupled to said at least one sensor effective to
discriminate between a soft target and a hard target dependent on
said electrical output; and a fuze that transmits a detonation
signal to an initiating explosive to thereby detonate said
munition, said detonation signal being sent at a time dependent on
target discrimination.
2. The multi-mode fuze of claim 1 wherein said at least one sensor
is a single piezoelectric crystal and said electrical output is a
voltage that is dependent on said rate of deceleration.
3. The multi-mode fuze of claim 2 wherein said logic circuit
determines that if said voltage is less than 3 volts, a soft target
has been impacted.
4. The multi-mode fuze of claim 1 wherein said at least one sensor
is an accelerometer and said electrical output is a voltage that is
dependent on said rate of deceleration.
5. The multi-mode fuze of claim 4 wherein said accelerometer is
MEMS device.
6. The multi-mode fuze of claim 1 wherein said at least one sensor
is two sensors, a soft target sensor disposed closer to said target
than a hard target sensor.
7. The multi-mode fuze of claim 6 wherein said soft target sensor
and said hard target sensor are independently selected from the
group consisting of piezoelectric crystals and mechanical
switches.
8. The multi-mode fuze of claim 6 wherein said soft target sensor
is actuated when a target is impacted sending a first electrical
signal to said logic circuit and said hard target sensor and sends
a second electrical signal to said logic circuit only if a hard
target is impacted.
9. The multi-mode fuze of claim 8 wherein said logic circuit is
programmed such that said second electrical signal overrides said
first electrical signal.
10. An explosive projectile, comprising: an aerodynamically shaped
metallic casing; an explosive contained within said metallic
casing; an initiating explosive contacting said explosive; a
multi-mode fuze communicating with said initiating explosive
effective to trigger detonation of said explosive either on impact
with a hard target or following a delay on impact with a soft
target.
11. The explosive projectile of claim 10 wherein said multi-mode
fuze is disposed forward of said explosive.
12. The explosive projectile of claim 10 wherein said multi-mode
fuze is disposed rearward of said explosive.
13. The explosive projectile of claim 10 wherein said multi-mode
fuze includes a soft target sensor that is actuated when a target
is impacted sending a first electrical signal to said logic circuit
and a hard target sensor that sends a second electrical signal to
said logic circuit only if a hard target is impacted wherein said
soft target sensor is disposed closer to said target than said hard
target sensor, a logic circuit electrically coupled to said at
least one sensor effective to discriminate between a soft target
and a hard target dependent on said electrical output and a fuze
that transmits a detonation signal to said initiating explosive to
thereby detonate said explosive.
14. The explosive projectile of claim 13 wherein said soft target
sensor and said hard target sensor are independently selected from
the group consisting of piezoelectric crystals and mechanical
switches.
15. The multi-mode fuze of claim 8 wherein said logic circuit is
programmed such that said second electrical signal overrides said
first electrical signal.
16. The explosive projectile of claim 10 wherein said multi-mode
fuze includes a piezoelectric crystal that has a first output when
a soft target is impacted and a second output when a hard target is
impacted, a logic circuit electrically coupled to said
piezoelectric crystal effective to discriminate between a soft
target and a hard target dependent on said electrical output and a
fuze that transmits a detonation signal to said initiating
explosive to thereby detonate said explosive.
17. The explosive projectile of claim 10 wherein said multi-mode
fuze includes a MEMS accelerometer that has a first output when a
soft target is impacted and a second output when a hard target is
impacted, a logic circuit electrically coupled to said MEMS
accelerometer effective to discriminate between a soft target and a
hard target dependent on said electrical output and a fuze that
transmits a detonation signal to said initiating explosive to
thereby detonate said explosive.
18. The explosive projectile of claim 10 having a shaped charge
liner disposed between a nose of said explosive projectile and said
explosive.
19. The explosive projectile of claim 18 wherein a distance between
said nose and said shaped charge liner is about equal to a set-off
distance of said shaped charge liner.
20. The explosive projectile of claim 13 having a shaped charge
liner disposed between a nose of said hard target sensor and said
explosive.
21. The explosive projectile of claim 20 wherein a distance between
said hard target sensor and said shaped charge liner is about equal
to a set-off distance of said shaped charge liner.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATION
[0001] This patent application relates to and claims priority to
U.S. Provisional Patent Application Serial No. 60/341,157 entitled
"Medium Caliber High Explosive Dual-Purpose Projectile With Dual
Function Fuze" by F. M. Bone that was filed on Dec. 14, 2001. The
subject matter of that provisional patent application is
incorporated by reference herein in its entirety.
STATEMENT OF GOVERNMENT RIGHTS
[0002] This invention was conceived and developed under internal
research and development finding and was not government funded.
BACKGROUND
[0003] 1. Field of Invention
[0004] This invention relates to a fuze for initiating detonation
of an explosive projectile. More particularly, the fuze includes a
target-sensing element that is capable of varying detonation delay
time in response to the hardness of the target.
[0005] 2. Description of Related Art
[0006] The current maximum effective range angle for ground attack
aircraft using medium caliber ammunition is 4000 to 5000 feet at a
slant angle of between 5.degree. and 15.degree.. Typically, the
munition employed by the ground attack aircraft is an armor
piercing incendiary (API) projectile, the effectiveness of which
depends on kinetic energy. API projectiles are effective against
hard (armor plated) targets but that effectiveness is reduced
against softer, unarmored, threats because the energy is not
distributed within the target. The current maximum effective range
places the attacking aircraft in, danger by exposing the pilot and
airplane to small arms fire and man-portable anti-aircraft
missiles.
[0007] Chemical energy projectiles produce effective terminal
shaped charge or explosively formed fragments. Though not used for
fixed wing ground attack aircraft, the projectiles can be effective
at extended ranges, 9000 to 12,000 feet, for armored target defeat.
The chemical energy projectiles are less effective against soft
targets due to the near instantaneous reaction of the fuze that
distributes energy on the surface of the threat.
[0008] One factor that influences the effectiveness of an explosive
munition against a target is the detonation delay following impact.
When a target is relatively soft, for example, if detonation occurs
after the projectile has entered the target, damage is enhanced by
placing the blast, fragments and incendiary effect inside the
target. In contrast, hard targets are more effectively defeated by
detonating a munition on impact with the target surface to produce
a chemical defeat by plasma jet or explosively formed fragment.
Accordingly, explosive projectiles frequently include a fuze that
is capable of delaying detonation dependent on the most effective
impact of the projectile.
[0009] One such fuze is disclosed in U.S. Pat. No. 5,872,324 by
Watson et al. A tri-mode fuze assembly includes a casing, that
serves as a structural containment for a booster pellet, which, in
turn, provides the initiation of a main warhead. A hard target
impact detonator is located on a forward end of the fuze assembly
providing a mechanical, instantaneous detonation of the warhead in
the event that the target impact results in a physical crushing of
the warhead. A second detonator located within the casing provides
a pyrotechnic timer-operated delay for penetration of hardened
targets. This timer is initiated by initial impact and continuous
deceleration of the warhead when the integrity of the warhead is
maintained. A third detonator provides an instantaneous,
void-sensing detonation capability for the fuze. Operation of the
third detonator is initiated by initial impact and the interruption
of the continuous deceleration required by the delay detonator.
Once target penetration begins, any variation in the rate of
deceleration results in an immediate initiation of the main warhead
by the void sensor.
[0010] U.S. Pat. No. 5,872,324 utilizes a firing pin to detonate
the explosive when an impenetrable target is encountered and a
sensitive pyrotechnic time delay for hard but penetrable targets.
In the case of soft targets, a mechanical apparatus requiring very
strict adherence to small manufacturing tolerances is used to sense
deceleration. Successful actuation of a mechanical firing pin is
dependent on axial loading to drive the pin into a stab detonator.
If the pin enclosure receives a side load due to high oblique
impact, the energy can crush the pin or produce a load that is not
along the centerline to cause sufficient pin motion to perforate
the stab detonator. In addition to impact reliability, the
difficulty in manufacturing these components, temperature and
launch loads can cause unwanted variations in performance.
[0011] U.S. Pat. No. 5,255,608 by Min et al. discloses an
intelligent hard-target weapon providing a real-time determination
of target consistency during weapon penetration. Input signals are
provided by an accelerometer used as a primary sensor. On-line
concurrent processing of the data of a specific length facilitates
a few different modes of feature extraction. The processor provides
a robust, real-time decision making for the fuze utilizing sensor
signals (accelerometer data). The feature sets utilized include
(1)amplitude profiles of the signals, (2) their derivative
profiles, and (3), the measure of their abrupt changes. The purpose
is to provide for detonation at the proper point as the high-speed
penetrator passes through various layers such as concrete, steel,
dirt, sand, etc. on its way to a valuable buried target. Real-time
decision making is provided for the fuze utilizing accelerometer
data.
[0012] U.S. Pat. No. 4,799,427 discloses an ignition device for a
projectile, in particular a guided missile, where the ignition
moment is controllable as a function of the impingement delay and
of the flight time of the projectile. This allows compensation for
the type of material comprising the target, e.g., hard or soft, and
for the amount of time the projectile has been airborne, thus
compensating for reduced projectile velocity at the time of
striking the target.
[0013] U.S. Pat. Nos. 5,872,324, 5,255,608, and 4,799,427 are
incorporated by reference in their entirety herein.
[0014] U.S. Pat. No. 4,375,192 by Yates et al., that is
incorporated by reference in its entirety herein, discloses a fuze
which is designed to initiate detonation upon penetration of a
target a preselected distance or after a preselected number of
cavities have been perforated by the warhead. Other, default or
salvage, modes are based upon breakup of the warhead, or
ricochet.
[0015] In the abovementioned patents, unreliable or expensive
mechanical or pyrotechnic means are used to trigger detonation, or
complex algorithms are employed to determine the status of the
projectile's penetration. There remains, therefore, a need for an
easily manufactured and reliable fuze that is capable of initiating
detonation on impact with a hard target or after a time delay on
impact with a soft target. This fuze is incorporated into a
projectile that combines the terminal effects of a chemical energy
projectile for hard target defeat with a delayed reaction to
effectively defeat soft targets.
SUMMARY OF THE INVENTION
[0016] Accordingly, it is an object of the invention to provide a
reliable fuze capable of detonating a projectile instantaneously or
after a time delay based on the magnitude of deceleration of the
projectile.
[0017] It is a feature of the invention that the fuze is useful for
projectiles impacting both hard and soft targets. It is another
feature that accelerometers are used to detect projectile
deceleration and communicate the magnitude to fuze logic that
determines whether to detonate the projectile instantaneously or
after a time delay.
[0018] It is an advantage of the invention that the use of
accelerometers and solid state logic to determine detonation makes
the fuze more reliable and less expensive than other fuzes. It is a
further advantage that terminal effects of the projectile are
maximized.
[0019] In accordance with the invention, there is provided a
multi-mode faze for a munition having at least one sensor that
generates an electrical output dependent on a rate of deceleration
when the munition impacts a target, a logic circuit electrically
coupled to the at least one sensor effective to discriminate
between a soft target and a hard target dependent on the electrical
output and a fuze that transmits a detonation signal to an
initiating explosive to thereby detonate the munition. The
detonation signal is transmitted at a time dependent on target
discrimination.
[0020] The multi-mode fuze of the invention may be incorporated
into an explosive projectile that includes an aerodynamically
shaped metallic casing, an explosive contained within the metallic
casing and an initiating explosive contacting the explosive. The
multi-mode fuze communicates with the initiating explosive to
trigger detonation of the explosive either on impact with a hard
target or following a delay on impact with a soft target.
[0021] The above stated objects, features and advantages will
become more apparent from the specifications and drawings that
follow.
IN THE DRAWINGS
[0022] FIG. 1 illustrates in partial cross-section representation a
projectile of the invention having a nose located dual function
fuze.
[0023] FIG. 2 illustrates in cross-sectional representation a
projectile of the invention having a base located dual function
fuze.
[0024] FIG. 3 graphically illustrates the rate of deceleration
following impact with either a soft or a hard target.
[0025] FIG. 4 is a block diagram Illustrating the application of a
fuze logic sequence.
[0026] FIG. 5 graphically illustrates the relationship between
impact acceleration and voltage output for a piezoelectric
crystal.
DETAILED DESCRIPTION
[0027] 25-mm through 76-mm medium caliber ammunition is used on a
number of existing and future gun systems including assault
vehicles, amphibious assault vehicles, fixed wing aircraft, ships
and tanks. The targets may be soft targets such as lightly armored
vehicles, including personnel carriers, trucks and airplanes,
ground support communication stations and radar installations.
These targets are generally supported by 0.039 inch (1 mm) aluminum
in the form of aircraft or 0.039 to 0.250 inch (1.0 to 6.4 mm)
steel for vehicles and ground support equipment. Other targets are
hard targets such as heavily armored vehicles, tanks and bunkers.
These targets are generally supported by 0.5 to 1.5 inch (12.7 to
38.0 mm) rolled homogeneous armor (RHA) plate with a hardness in
the range of 300 to 360 BHN (Brinell Hardness Number).
[0028] BHN is a number related to the applied load and to the
surface area of the permanent impression made by a ball indenter
computed from the equation:
BHN=2P/.pi.D((D-(D.sup.2-d.sup.2).sup.1/2))
[0029] Where P is the applied load in kgf, D is the diameter of
ball in mm, and d is mean diameter of the impression in mm.
[0030] FIG. 1 illustrates in partial cross-section representation a
projectile 10 of the invention having a nose-located dual function
fuze. The projectile 10 has a metallic casing 12, typically formed
from steel, that forms fragments when an explosive 14 within the
casing 12 is detonated. The fragments enhance terminal effects
within the threat along with a shaped charge jet or explosively
formed fragment as described below. One suitable explosive 14 is a
plastic bonded explosive (PBX).
[0031] Housed within a nose portion of the projectile 10 is a soft
target sensing element 16 that may be a mechanical switch or a
piezoelectric crystal. When the projectile 10 impacts a relatively
soft, unarmored, target such as an aircraft or ground support
equipment, deformation of the nose 18 is small as compared to hard
target engagement. In one embodiment, the soft target nose
deformation closes a mechanical switch in the soft target sensing
element 16. This switch starts a timer to delay projectile 10
reaction until the projectile is well inside the target. A suitable
delay is from 150 to 300 microseconds.
[0032] Alternatively, the soft target sensing element 16 includes a
piezoelectric crystal having an output proportional to the impact
shock wave carried into the projectile nose 18. The signal wave
form from the piezoelectric crystal is analyzed by a logic circuit
contained within fuze 20 to start the time delay for reaction
inside the target.
[0033] Further, the piezoelectric crystal in soft target sensing
element 16 can be used to detect harder targets as described below.
This approach simplifies projectile design and enhances reliability
by using one sensing piezoelectric crystal located in the
projectile nose 18.
[0034] Located rearward of the of the soft target sensing element
16 is a hard target sensing element 22. Typical armored or hardened
threats that can be effectively engaged with medium caliber
ammunition are protected with between 0.5 inch and 1.5 inch of
Rolled Homogeneous Armor Plate with a hardness ranging between 300
and 360 BHN. The harder target resistance increased projectile nose
18 deformation actuating the hard target sensing element. Hard
target sensing element 22 may be a mechanical switch or second
piezoelectric crystal that sends a signal to the logic circuit of
the fuze 20 when nose 18 deformation reaches the hard target
sensing element. Alternatively, as described above, a single
piezoelectric crystal may be utilized that generates a different
waveform from that generated on soft target impact and the fuze
logic discriminates between the two.
[0035] One suitable piezoelectric device for determining
acceleration is a piezoelectric element such as those made by
Kinetic Ceramics, Inc. which has an output proportional to the
impact shockwave carried into the projectile nose 18. The signal
waveform from the piezoelectric element is analyzed by the fuze
logic to instantaneously detonate the projectile or start the time
delay.
[0036] An effective way to defeat a hard target is with a
penetrating jet that can be either a shaped charge plasma jet or an
explosively formed fragment. Shaped charge liner 24 is formed from
a suitable liner material such as copper, tantalum or tungsten.
Disposed rearward of the convex surface of the shaped charge liner
24 is the explosive 14. When detonated, the explosive generates a
shock wave that collapses the liner expelling a plasma jet formed
from liner material forwardly from the projectile 10. There is a
set-off distance between the shaped charge liner and the target at
which the plasma jet has maximum momentum (a combination of jet
length and jet speed). A distance "d" between the hard target
sensing element 22 and shaped charge liner 24 is set such that the
liner is collapsed as close to the set-off distance from the target
as possible. A more detailed explanation of shaped charge liners is
found in U.S. Pat. No. 6,393,991 to Funston et al., that is
incorporated by reference in its entirety herein.
[0037] If the hard target sensing element 22 generates a signal,
the fuze logic overrides any delay remaining from the soft target
sensing element 18 signal to insure the shaped charge liner is
collapsed at approximately the set-off distance.
[0038] Additional elements of the projectile 10 include a safe and
arm device 26 to prevent premature detonation and detonation of
projectiles that miss the target. The projectile 10 must be safely
armed before the fuze is activated. The arming of the projectile a
safe distance after expulsion from a launch muzzle may achieved by
a combination of a mechanical action out-of-line rotor supplemented
by an electrical timer. Predetermined levels of linear
acceleration, commonly referred to as setback, and radial forces,
commonly referred to as spin load, must be met to satisfy the dual
environment safe and arm functions for aligning a primary fuze
rotor enclosed detonator with a secondary fuze energetic element or
booster. After mechanical safe and arm conditions are satisfied,
the arming distance is further extended by an electronic time delay
started at launch. After approximately 0.5 second time of flight
from the muzzle, the electrical circuit for fuze function is closed
to await a detonation signal. If no signal is received within the
time required for the projectile to reach the target plus some
margin of error, the projectile is disarmed.
[0039] An initiating explosive 28, such as RDX
(1,3,5-trinitro-1,3,5-triaz- acyclohexane) is detonated by an
electric signal received through leads 30 transmitted from fuze 20.
The shock wave from detonation of the initiating explosive 28
detonates explosive 14.
[0040] FIG. 2 illustrates in cross-sectional representation a
projectile 40 in accordance with a second embodiment of the
invention having a base-located dual function fuze. A number of the
elements of this projectile are similar to the elements of
preceding projectile 10 and those similar elements are identified
by like reference numerals. Communicating with, and preferably
contained within, fuze 20 is an accelerometer 42. The accelerometer
is capable of detecting the rate of projectile deceleration and
generating an electrical signal proportional to the rate of
deceleration. Accelerometer 42 may be a mechanical or piezoelectric
device, but micromechanical systems (MEMS) are preferred.
[0041] MEMS is the integration of mechanical elements, sensors,
actuators, and electronics on a common silicon substrate using
microfabrication technology. While the electronics are fabricated
using integrated circuit (IC) process sequences (e.g., CMOS,
Bipolar, or BICMOS processes), the micromechanical components are
fabricated using compatible "micromachining" processes that
selectively etch away parts of the silicon wafer or add new
structural layers to form the mechanical and electromechanical
devices. MEMS accelerometers are typically much smaller, more
functional, lighter, more reliable, and are sold for a fraction of
the cost of the conventional macroscale accelerometer elements.
[0042] While the MEMS accelerometer has been disclosed in
combination with a base-loaded fuze, the MEMS accelerometer may
also be utilized with a nose-load fuze system as well.
[0043] FIG. 3 graphically illustrates the rate of deceleration
following impact with either a soft target (reference line 52), a
hard target (reference line 54) or a miss (reference line 50). The
velocity of a projectile in normal flight experiences relatively
smooth acceleration due to variables such as gravity or drag force
(a function of the velocity squared). Once the flight has exceed a
first threshold time (reference point 56) the projectile is armed.
If the flight exceeds a second threshold time (reference point 58)
without a sudden decrease in velocity, a miss is determined and the
projectile is disarmed.
[0044] When the projectile impacts a soft target, a calculation of
the rate of change of acceleration, .DELTA.a, over a time interval,
.DELTA.t, yields a first value for .DELTA.a. When the projectile
impacts a hard target, the value of .DELTA.a is considerably
larger. A simple embodiment of the fuze logic algorithm can be
described as follows.
[0045] If .vertline..DELTA.a.vertline..gtoreq..times. then y=0;
[0046] If .vertline..DELTA..vertline.<.times. then y=150
microseconds.
[0047] Where a equals acceleration of projectile;
[0048] x equals the predetermined threshold magnitude for
discriminating between a hard target and a soft target. X must
exceed some minimal value to indicate that a target has been
impacted.; and
[0049] y equals the time delay.
[0050] Considering a maximum impact velocity at 3000 feet per
second (914.4 meters per second), a sampling rate of 1 microsecond
is adequate to assure correct logic function prior to destruction
of the sensing elements of the projectile.
[0051] The fuze logic is best understood with reference to FIG. 4.
The fuze logic may utilizes a pre-programmed microprocessor such as
those made by KDI Precision Products, Inc. of Cincinnati, Ohio. The
microprocessor is a solid state device powered by electrical energy
provided by a set back generator such as those made by Miltec SA.
The electrical energy stored in a capacitor sets the threshold
levels in the fuze for delay or instantaneous reaction decision.
The microprocessor with storage capacitor is encapsulated in a
molded polymer to resist the affects of acceleration and spin
loads.
[0052] An accelerometer 42 is electronically connected to fuze
logic 60. The accelerometer 42 is capable of transmitting a
proportional signal 62 to fuze logic 60. Fuze logic 60 receives
proportional signal 62, compares it to magnitude 64, and transmits
either: (1) signal 66 instantaneously to detonate the initiating
explosive 28 if signal 62 meets or exceeds magnitude 64, or (2)
signal 68 after a time delay 70 if signal 4 falls below magnitude
64.
[0053] A medium caliber projectile will defeat a soft target with
impact obliquities up to 75 degrees NATO. At these obliquities, the
axial component of the acceleration should be adequate to trigger
detonation. For a hard target or a greater obliquity however, a
triaxial sensing element would be useful to assure function if the
axial component is very small.
[0054] The use of a single piezoelectric crystal to determine
target type and to provide that information to the fuze logic is
illustrated by the Example that follows.
EXAMPLE
[0055] A piezoelectric crystal from Kinetic Ceramics, Inc. of
Hayward, Calif. having a rated sensitivity of 0.37 mV/g was
incorporated into a simulated projectile. Weights were dropped on
the nose of the projectile from varying heights to simulation
impact accelerations of varying g-forces. An impact acceleration
force of from 1,000 g to 10,000 g was deemed to simulate impact
with a soft target and an impact acceleration in excess of 20,000 g
was deemed to simulate impact with a hard target. The voltage
generated by the piezoelectric crystal following these simulated
impact was recorded. As shown from FIG. 5, the target type was
readily determined from the voltage output. An output of about 3
volts or less corresponded to a soft target and an output of about
4.4 volts or more corresponded to a hard target. There was a
standard deviation in the measured voltages of about .+-.17%.
[0056] It is apparent that there has been provided in accordance
with the invention a fuze that fully satisfies the objects,
features and advantages disclosed hereinabove. While disclosed in
accordance with specific embodiments of the invention, it is
apparent that many alternatives, modifications and variations are
equally applicable to the invention and these alternatives,
modifications and variations are equally encompassed within the
scope of the claims that follow.
* * * * *