U.S. patent number 3,758,052 [Application Number 05/844,727] was granted by the patent office on 1973-09-11 for system for accurately increasing the range of gun projectiles.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Navy. Invention is credited to Robert L. McAlexander, Lilburn G. Stout.
United States Patent |
3,758,052 |
McAlexander , et
al. |
September 11, 1973 |
SYSTEM FOR ACCURATELY INCREASING THE RANGE OF GUN PROJECTILES
Abstract
The present invention is a gun system which utilizes rocket
assisted projiles and accurately controls their placement. The
projectile is fired by a gun and actual trajectory variables are
compared in a computer with desired trajectory conditions. If there
is a difference, the firing time of the rocket is altered to make
the actual trajectory variable correspond to the desired condition.
A radar system is utilized by the computer to obtain the trajectory
information. A transmitter is connected to the computer to send the
firing signal to a receiver mounted in the projectile.
Inventors: |
McAlexander; Robert L.
(Saratoga, CA), Stout; Lilburn G. (Falmouth, VA) |
Assignee: |
The United States of America as
represented by the Secretary of the Navy (Washington,
DC)
|
Family
ID: |
25293483 |
Appl.
No.: |
05/844,727 |
Filed: |
July 9, 1969 |
Current U.S.
Class: |
244/3.14;
89/41.07; 244/3.22; 102/380 |
Current CPC
Class: |
F42C
13/047 (20130101); F42B 15/00 (20130101) |
Current International
Class: |
F42C
13/00 (20060101); F42C 13/04 (20060101); F42B
15/00 (20060101); F42b 013/30 () |
Field of
Search: |
;102/49.7 ;244/3.22,3.14
;89/49.7SW |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pendegrass; Verlin R.
Claims
1. A system for controlling the placement of a gun-launched
projectile comprising:
a projectile adapted to be launched from a gun;
booster rocket means incorporated in said projectile for imparting
additional thrust along the longitudinal axis of the projectile
subsequent to the launching of said projectile from said gun;
means located remote from said projectile for measuring actual
projectile trajectory parameters;
a computer located remote from said projectile responsive to said
measuring means which utilizes the measured trajectory parameters
to provide an indication of when said measured trajectory
parameters differ from the desired projectile trajectory parameters
and which generates an initiate signal when the measured variables
and the desired conditions differ;
a transmitter connected to said computer and operable to send said
initiate signal to said projectile;
said projectile further comprising a radio receiver to receive the
initiate signal from said transmitter;
Wherein the rear section of said projectile forms a booster rocket
which is actuated by said initiate signal received by said radio
receiver to provide additional thrust to said projectile along its
longitudinal axis.
2. A system as in claim 1 further comprising a squib connected to
said radio receiver for firing said rocket booster.
3. A system in claim 2 wherein said rocket booster includes:
a nozzle through which ignited rocket fuel is directed; and
solid rocket fuel for powering said rocket booster;
said radio receiver being mounted in said nozzle.
4. A system as in claim 3 further comprising an eccentric plug
mounted in said nozzle to protect said radio receiver and to
prevent premature ignition of said rocket.
5. A system as in claim 4 further comprising
a centrifugal switch connected to said squib; and
a power supply connected to said centrifugal switch for providing
energy to ignite said squib;
said centrifugal switch being operative to prevent power from
reaching said squib until sufficient spin is imparted to said
projectile.
6. A system as in claim 5 further comprising:
a discriminator connected to radio receiver to protect the system
from erroneous ignition signals; and
a level detector connected to said discriminator and said squib to
further insure that the squib is ignited at the proper time.
7. A system as in claim 6 further comprising a delay circuit
connected between said centrifugal switch and said squib to prevent
premature ignition of said squib.
Description
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or
for the Government of the United States of America for governmental
purposes without the payment of any royalties thereon or
therefor.
BACKGROUND OF THE INVENTION
Field of the Invention
This invention is directed to the field of ballistic control. More
particularly, this invention is directed to a system which
accurately increases the range of gun projectiles.
Description of the Prior Art
No effective inexpensive method of assuring the accurate placement
of projectiles while at the same time increasing their range is
found in the prior art.
One type of prior art system for assuming accurate placement of
projectiles utilized an explosive charge which was mounted on the
side of the missile. This method however has a number of inherent
disadvantages. The first disadvantage is that if the explosive is
not facing in the proper direction, the projectile will be driven
off of the desired trajectory. The hardware necessary for this
operation is complex and expensive. In addition, the explosive
charge is exhausted when once fired and cannot be used to increase
the range of the projectile. Finally, the explosive charge cannot
propel the projectile forward. Thus, if the projectile is subjected
to a strong headwind or down draft, the charge will not enable the
projectile to maintain the desired trajectory.
Ordinary guided missiles carrying explosive warheads do not offer
the advantages obtainable with accurately fired guns. Guided
missiles are extremely expensive and bulky. These missiles require
elaborate control systems and specifically designed launching
areas. They are not compatable with conventionally equipped
ships.
SUMMARY OF THE INVENTION
The present invention accurately controls the placement of
rocket-assisted gun projectiles and offers significant advantages
over the prior art. The projectile utilized is simply designed and
is very rugged. Its clost is minimal in relation to that of guided
missiles. It can be fired from conventional guns and control can be
achieved at almost any point in its trajectory.
The inventive system utilizes rocket-assisted projectiles. When the
projectiles are fired from the gun, a radar tracker follows their
trajectory and feeds it to a computer which compares actual
trajectory variables with the desired trajectory conditions. If
there is a difference the computer will change the time at which
the initiating signal is sent to a transmitter. The transmitter in
turn sends this signal to the projectile to activate the booster
rocket to bring the actual trajectory variable into correspondence
with the desired trajectory condition.
It is an object of the present invention to provide an inexpensive
rugged system for accurately controlling the placement of
gun-launched projectiles.
It is a further object of this invention to provide a system which
will provide post launch, inflight control of gun-fired projectiles
from a ground based position.
It is a further object of the present invention to provide a system
capable of compensating inflight for errors incurred during launch.
Such errors include gun jump, variation in initial velocity,
variation in elevation angle and any other measurable gun launch
error.
Other objects, advantages and novel features of the invention will
become apparent from the following detailed description of the
invention when considered in conjunction with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic of the inventive system;
FIG. 2 is a cross-section of the rocket-assisted projectile
utilizes; and
FIG. 3 is a circuit diagram of the receiving and firing
circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawing and in particular FIG. 1 which shows
the inventive system and various trajectories of the
rocket-assisted projectile 11. The inventive system utilizes a gun
12 to fire the projectile 11. A computer 13 is connected to the gun
as well as to the radar 14 and transmitter 15.
Initially, the gun is aimed and its firing angle fed to computer
13. When the gun is fired, a trigger signal is sent to a clock in
the computer. Ten seconds after firing, the computer activates the
radar 14 which sends a pulse to the projectile 11. This pulse is
reflected off the projectile and received by the radar. The radar
gives a reading of the azimuth and elevation of the projectile.
This reading is a measure of the actual launch velocity (which is
just one of the possible launch errors) and trajectory time of the
projectile and is fed to the computer where its impact point is
calculated. The desired impact point is compared to the predicted
impact point and an initiation time is generated to insure the
desired range is reached. The initiation signal is sent together
with the output from a computer clock to a coincidence circuit.
When the clock has counted off the requisite time, the signal is
sent to the transmitter.
The computer is programmed for all the desired trajectories and
impact points of all the firing angles and muzzle velocities of the
gun. This information is generated in the computer as a function of
time. The computer thus knows that at a firing angle of 30.degree.
the rocket motor must be pulsed at a certain time, such as 15
seconds after firing in order to land at the desired impact
area.
If the desired and actual trajectory and impact points differ, then
the time that the pulse is sent to start the rocket in the
projectile 11 must differ.. Thus, assuming a desired trajectory of
30.degree. at the 10 second point and a firing time of 15 seconds
(trajectory A, FIG. 1), the projectile will go beyond the impact
point if the actual trajectory angle is 35.degree. (trajectory B)
at the 10 second point. If the actual angle is 25.degree.
(trajectory C) at the 10 second point, the projectile will fall
short of the impact area.
The computer provides compensation for these variations and changes
the firing time of the rocket when there is a difference between
the actual and desired trajectory variables. Thus as seen in FIG.
1, if the desired firing of the rocket occurred at the apex of the
unassisted trajectory, the actual firing must occur after this
point when the actual trajectory is 35.degree. at 10 seconds.
Similarly, the actual firing must occur before this point when the
actual trajectory is 25.degree. at 10 seconds. At the 35.degree.
firing point the rocket motor vector will have a down thrust which
will shorten the range while at the 25.degree. firing point the
rocket motor vector will have an upward thrust which will increase
the projectile's range.
The projectile 11 utilized is shown in detail in FIG. 2. The
projectile is comprised of a nose cone 21, an explosive chamber 22
and a rocket chamber 23. An explosive 24 and a detonator 25 are
contained within the explosive chamber 21. A rocket is formed in
the rocket chamber and comprises solid fuel 26, firing squib 27 and
nozzle 28.
Eccentric plug 29 and O ring 30 seal the rocket. These items serve
two purposes. When the projectile is in storage, they protect the
inside of the rocket chamber. When the projectile is fired, they
keep the explosive force out of the chamber and prevent premature
ignition of the rocket.
The ignition train of the rocket is also mounted inside the rocket
chamber 23. The train includes half-wave antenna 31 which is
encased in epoxy or the like for protection and a support plug 32
which holds the receiving and firing circuit 33 and connects it
with the antenna. The receiving and firing circuit is connected
through a coaxial cable 34 to the squib 27.
The receiving and firing circuit is shown in more detail in FIG. 3.
It includes an F.M. receiver 41, a frequency discriminator 42 and a
level detector 43 connected in series to the firing circuit 44. A
power supply 46, centrifugal switch 47 and a delay circuit are also
connected in series to the firing circuit 44 which is in turn
connected to the squib 27.
The centrifugal switch disconnects the power supply, which is
generally a battery, from the firing circuit when the projectile is
in storage. This preserves the charge on the battery and protects
against premature firing of the rocket.
Turning now to the operation, the gun will fire the projectile and
impart a spin and a forward velocity to it. As the spin builds up
the eccentricity of the plug 29 will cause it to loosen. It will
then move out of the nozzle area and away from the projectile
exposing the antenna 31.
The spin of the projectile will also close centrifugal switch 46
and begin the charging of a capacitor in the firing circuit. The
delay circuit 47 comprises a resistor which controls the time
constant of the capacitor. This time constant is made long enough
to prevent possible ignition of the rocket until it is well beyond
the gun launch area.
At the time selected for firing of the rocket the transmitter 15
sends a frequency modulated signal to the projectile. This signal
is picked up by the receiver through antenna 31 and passed to
frequency discriminator 42 and level detector 43. The discriminator
and level detector protect against spurious signals and insure that
the rocket is not improperly ignited.
The signal passed by the level detector closes a switch in the
firing circuit. This connects the firing capacitor to the squib.
The squib is then ignited and in turn ignites the rocket.
Thus it is seen that a new and improved system for increasing the
range and accuracy of gun launched projectiles has been provided.
The system is rugged and simply constructed.
Obviously many modifications and variations of the present
invention are possible in the light of the above teachings. What is
claimed is:
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