U.S. patent number 3,855,930 [Application Number 05/068,953] was granted by the patent office on 1974-12-24 for personnel distress signal.
This patent grant is currently assigned to MB Associates. Invention is credited to Donald R. Duffy, Stephen F. Mulich, Steven J. Salter.
United States Patent |
3,855,930 |
Mulich , et al. |
December 24, 1974 |
PERSONNEL DISTRESS SIGNAL
Abstract
The disclosure relates to an improved miniature rocketry system
used for propelling a signal flare and includes a pair of generally
tubular shaped housings in telescoped engagement, wherein is
disposed a propulsion charge, a propulsion charge ignitor, a delay
train or timing fuse, a signal display flare and means for insuring
complete combustion of all the pyrotechnics. A nozzle structure is
provided at one end of the housing to impart a gyroscopically spin
stabilized guidance to the rocket trajectory, and an improved
propellant spacer is interposed between the nozzle structure and
the propulsion charge for the purpose of separation of the members
and retention of the propulsion charge during combustion
thereof.
Inventors: |
Mulich; Stephen F. (San Ramon,
CA), Duffy; Donald R. (Dublin, CA), Salter; Steven J.
(Walnut Creek, CA) |
Assignee: |
MB Associates (San Ramon,
CA)
|
Family
ID: |
22085775 |
Appl.
No.: |
05/068,953 |
Filed: |
September 2, 1970 |
Current U.S.
Class: |
102/342;
102/351 |
Current CPC
Class: |
F42B
4/06 (20130101) |
Current International
Class: |
F42B
4/00 (20060101); F42B 4/06 (20060101); F42b
013/40 () |
Field of
Search: |
;102/34.3,34.5,34,49.3,34.4,35.6,37.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Stahl; Robert F.
Attorney, Agent or Firm: Harness, Dickey and Pierce
Claims
We claim:
1. In a rocket device,
an elongated generally tubular shaped housing, a cylindrically
shaped propulsion charge in one end of said housing,
first means for directing the products of combustion of said charge
rearwardly of said housing in a manner so as to impart rotary
motion to said device as it is propelled forwardly by said
charge,
signal means in said housing,
second means including a combustible material for igniting said
signal means at a predetermined time after said propulsion charge
has been ignited, and
spacing means located between said first means and said charge for
operatively supporting said propulsion charge, said spacing means
including an annular shaped transversely extending web section and
an axially extending flange located about the outer periphery of
said web section and defining symetrical portions on opposite axial
ends of said web section, said symetrical portions defining
identically formed first and second recess means located on
opposite axially spaced ends of said spacing means, one of said
recess means cooperatively receiving and radially securing one end
of said charge while the opposite symetrical portion selectively
locates said charge in preselected axially spaced relationship
relative to said first means.
2. In a personnel distress signal for use in a miniature rocketry
system having gyroscopic guiding means, a propulsion charge, a time
delay fuse, and signaling means, the improvement comprising means
including the blended combination of a pressure insensitive
chemical composition and a low gas output chemical composition for
igniting said propulsion charge in any natural environment, said
pressure insensitive chemical composition comprising granules of
boron potassium nitrate and said low gas output chemical
composition including finely ground boron barium chromate, whereby
at low environmental temperatures, the combustion heat requirement
is satisfied by said pressure insensitive composition while at high
temperatures, the combustion pressures are not increased by the
rate of burn of said pressure insensitive composition.
3. A personnel distress signal for use in any natural environment
comprising:
motor housing means defining first and second axially spaced
tubular shaped sections,
nozzle means located in one end of one of said first and second
sections for imparting a gyroscopic motion to said signal;
motor means located in said one section for providing a source of
combustible energy to said signal;
ignition means for igniting said motor means comprising a pressure
insensitive chemical composition and a low gas output chemical
composition;
signal means connected to said motor housing means for providing a
protechnic display, said signal means including a flare cup and a
flare pellet located in said cup, said flare pellet including an
inward concavely shaped recess, said second section of said housing
means extends inwardly in said recess; and
time delay fuse means located in the other of said sections for
energizing said signal means after a predetermined time interval
commencing after ignition of said motor means.
4. The distress signal as recited in claim 3 wherein one end of
said flare cup is formed from a material having a high resistance
to oxidation and which is capable of burning with said pellet
whereby to contribute to the display.
5. The distress signal as recited in claim 3 wherein one end of
said flare cup includes an arcuately shaped wall whereby to promote
foliage penetration and to increase the overall flight
characteristics.
6. The distress signal as recited in claim 5 wherein said wall
approaches the form of an ogive.
7. The distress signal as recited in claim 3 which includes means
for inhibiting the rate of combustion of said pellet.
8. The distress signal as recited in claim 7 wherein said
inhibiting means includes a paper tube located between an inner
peripheral surface of said cup and an outer peripheral surface of
said pellet.
9. The distress signal as recited in claim 8 which includes a resin
like material coating said tube whereby to prevent an accordian
effect when said pellet is disposed in said cup.
10. The distress signal as recited in claim 3 which includes flare
ignition means centrally located in said recess for igniting said
pellet.
11. The distress signal as recited in claim 3 which includes primer
means centrally located in said nozzle means for initiating
combustion of said ignitor means.
12. The distress signal as recited in claim 3 which includes
rupturable diaphragm means located in an inward side of said nozzle
means for hermetically sealing the interior of said housing means
and to facilitate a pressure build up therein.
13. The distress signal as recited in claim 12 wherein said motor
means is subject to vaporization at high ambient temperatures and
which includes sealing means located between said primer means and
said nozzle means and between said nozzle means and said housing
means for retaining said vapor.
14. The distress signal as recited in claim 3 which includes spacer
means located between said nozzle means and said motor means to
retain said last mentioned means during combustion thereof.
15. The distress signal as recited in claim 14 wherein said spacer
means is comprised of an annular shaped disc having an axially
extending flange carried by an outer peripheral surface thereof,
said flange extending equally in opposite axial directions relative
to the plane of said disc whereby to define first and second
recesses on opposite sides of said disc.
16. The distress signal as recited in claim 15 wherein one end of
said motor means engages one of said recesses.
17. The distress signal as recited in claim 15 which includes
shoulder defining means formed on an inner surface of one of said
sections of said housing means locatably receiving one end and an
outer peripheral surface of said flange.
18. The distress signal as recited in claim 3 wherein said motor
means includes a centrally located, axially extending passage and
wherein said ignition means is disposed in said passage.
19. The personnel distress signal of claim 3 wherein the pressure
insensitive chemical composition is Boron Potassium Nitrate.
20. The personnel distress signal of claim 3 wherein the low gas
output chemical composition is Boron Barium Chromate.
21. The distress signal as recited in claim 3 wherein said housing
means includes orifice means located between said first and second
sections and on one side of said fuse means for containment of the
reaction products thereof.
22. The distress signal as recited in claim 3 wherein said fuse
means includes a concavely shaped recess located in each opposite,
axially disposed surface.
23. The distress signal as recited in claim 3 which includes
shoulder means formed in an outer surface of one of said first and
second sections of said housing means for telescopically receiving
the other of said sections.
24. The distress signal as recited in claim 3 which includes char
and bubble forming means responsive to heat generated by said
signal means for retarding the rotary motor of said distress
signal.
25. The distress signal as recited in claim 24 wherein said last
mentioned means includes a paint coating located on the exterior
surface of said signal means.
Description
RELATED APPLICATION
Reference may be had to the Robert Mainhardt et al. application,
Ser. No. 694,208, filed Dec. 28, 1967, now abandoned for "Rotatable
Rocket Having Means for Preventing Flameout Due to Centrifugal
Force Created During Rotation Thereof" for a disclosure of a rocket
over which the rocket of the present invention has improved
features.
BACKGROUND OF THE INVENTION
Heretofore miniature rocketry propellant systems have been unable
to function universally with a reliability that was commercially
acceptable. For a miniature rocket, carrying a useful payload to
achieve the desired flight trajectory, the propulsion system must
provide a variety of functions which commence with proper
propellant ignition. After the propellant is ignited, a suitable
chamber pressure and burn rate relationship must be maintained for
the purpose of initiating and sustaining rocket propulsion until
the desired trajectory is obtained.
One of the problems associated with reliability is the fact that
the conventional propellant ignitors used in miniature rocketry
systems are limited to propellant ignition capabilities restricted
to a narrow range of temperature extremes and other environmental
conditions. At low temperatures, for example, in conventional
propellant systems, the chamber pressure is lower prior to ignition
thereby causing a lower chamber pressure during propellant
combustion. Furthermore, the burning rate of the conventional
propellant is slower, thereby affording a propellant combustion
pressure which has been found to be inadequate. Conversely, in
conventional propellant systems when high temperature environmental
conditions are experienced, the chamber pressures, along with the
extremely high temperature produced by propellant combustion exceed
optimum conditions, which often results in motor casing
failure.
At extremely low temperatures, motor casing failure may also be
experienced which may be attributed to a splitting of the
propellant due to the cold. If the propellant is fractured, a
greater surface area than is desirable is available for combustion
which also may result in excessive chamber pressures of a
sufficient magnitude to burst or split the motor casing. Thus the
problem involves obtaining propellant combustion which will not
over-pressurize at high temperatures, nor under-pressurize at low
temperatures. Further for propellant combustion to occur reliably
over a broad temperature range, a combustion pressure sensitizer is
necessary for lower and higher temperature extremes. Most
conventional ignition materials however have been found to be
pressure sensitive. In the subject miniature rocketry system the
ignition energy is supplied from a material which is sufficiently
pressure insensitive to provide similar combustion characteristics
at many extremes of temperature.
A further problem of previous rocketry propellant systems resides
in the propellant spacer component nominally located between the
propulsion charge and the nozzle structure. This component serves
the dual purpose of retaining the propulsion charge or propellant
during combustion while also serving to separate the nozzle casing
from the propellant. Previous designs were susceptible to being
installed backward which prevented the spacer from functioning as
intended. Also previous designs did not reliably retain the
propellant.
To overcome the lack of retention, previous rocketry systems
employed guiding prongs which were attached to the inside of the
motor casing for the purpose of retaining the propellant during
propellant combustion. By these means, however, the propellant was
found to disintegrate prematurely, drop into the propellant
passageway, and clog the nozzle port; thereby causing propulsion
failure. The origin of this failure was directly attributable to
the guide prongs in the motor casing. Hence, a need was created to
design an improved spacer element.
SUMMARY OF THE INVENTION
This invention relates generally to rocket-like devices and, more
particularly to a rocket propelled device for projecting a
personnel distress flare to an altitude such that the combustion of
said distress flare will provide an aerial pyrotechnic display.
It is accordingly a general object of the present invention to
provide new and improved rocket propelled signal flare.
It is a more particular object of the present invention to provide
a propellant ignition capability in a miniature rocket for use in
any natural environment.
It is still a more particular object of the present invention to
provide a distress signal which may be carried, along with a
launching means, on a person without impeding his movement and in
such a manner as to be comfortably worn.
It is another object of the present invention to provide a means of
environmentally protecting a miniature flare rocket, while
improving the overall rocketing functioning including altitude and
display duration.
It is yet another object of the present invention to provide a new
and improved miniature rocket signal flare of the above character
which is of simple design, is easy to assemble, and economical to
commercially manufacture.
Other objects and advantages of the present invention will become
apparent from the following detailed description taken in
conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal cross sectional view of a personnel
distress signal in accordance with a preferred construction of the
present invention;
FIG. 2 is a transverse cross sectional view taken along the line
2--2 of FIG. 1; and
FIG. 3 is a transverse cross sectional view taken along the line
3--3 of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to the drawings, a personnel distress signal,
generally designated by the numeral 10, is shown as comprising a
flare assembly 12 for providing a pyrotechnic display, and a motor
assembly 14 for providing the guidance and propulsion
capability.
The flare assembly 12 is located on the right end of the personnel
distress signal 10 as viewed in FIG. 1, and is comprised of a flare
cup 16 wherein is disposed a signal flare pellet 18 and a suitable
flare pellet ignitor 20.
The flare cup 16 is preferably constructed from a material having a
high resistance to oxidation and suitable to be impact extruded.
Aluminum has been found to exhibit these qualities and also is
capable of burning with the flare pellet 18 which provides an
additional benefit by contributing to the illumination. Other
useful materials include, but are not limited to, various plastics
and magnesium.
The flare cup 16 itself is comprised of an arcuate shaped forward
end wall 22 wherefrom its outer periphery is rearwardly extended an
elongated tubular skirt 24. The arcuate shape of the end wall 22 is
adapted to approach the form of that of an ogive which has been
found to be the optimum configuration for promoting foliage
penetration and increasing the overall flight characteristics of
the rocketry system thereof. With respect to increased flight
characteristics the ogive shape has been found to produce less
aerodynamic drag which therefore affords higher altitudes.
To assure total combustion of the flare pellet 18, the rate of
combustion is inhibited by restricting the combustion area. This
inhibition is accomplished by an elongated paper tube 26, cut
perpendicularly at both open ends, and having an outside diameter
slightly less than the inside diameter of the skirt 24 of the flare
cup 16 to accommodate insertion therewithin. Prior to insertion,
the paper material is preferably coated with a resin like substance
to prevent an accordian effect of the paper tube 26 at the time of
flare pellet compaction as shall become apparent as this
specification proceeds.
When the flare cup 16 is used without a paper tube 26, it has been
found that the flare cup is consumed at a faster rate than is the
flare pellet 18, and as a result thereof the sides of the flare
pellet begin igniting. The heat absorbed by the flare pellet 18 at
the sides and in front of the burning surface weakens the flare
pellet 18 causing the pellet to retain a low strength
characteristic in the heat zone. As the flare cup is spinning,
flare pellet combustion occurs simultaneously. Therefore, by
weakening the flare pellet in the heat zone, the burning surface
tends to fly off thereby extinguishing the flare pellet
prematurely. Premature extinguishing of the flare pellet is
believed to occur with greater frequency at the interface between
the flare pellet contractions that at other areas of the flare
pellet 18.
The flare pellets 18 are adapted to provide a variety of distress
signals depending on the composition of the pyrotechnic material
inserted into the flare cup 16. Examples include infrared,
ultraviolet, explosive smoke, strip markers, beacons, or balloons.
The desired flare pellets 18 are initially pre-pressed to volume
before being inserted into the flare cup 16. The flare pellets 18
are then further compacted to conform to the shape of the flare cup
with a recessed concave area 27 located at its rearward surface
wherein is centrally disposed the flare pellet ignitor 20, such as
black powder or the like. The flare pellet ignitor 20 is
correspondingly pre-pressed to shape prior to insertion into the
concave area 26 of the flare pellet 18, and further compacted upon
insertion to correspond to an inward concave surface thereof.
The motor assembly 14 is comprised of a motor and delay housing 28
wherein is disposed a nozzle structure 30, a propellant spacer 32,
a propellant cartridge 34, a propellant cartridge ignitor 36, and a
delay train or time fuse 38.
The motor and delay housing 28 is preferably constructed from a
machinable metal, such as steel, which is capable of containing
propellant combustion pressures without rupturing. To the finished
housing 28 a protective coating, such as cadmium, is applied to
provide environmental protection.
The motor and delay housing 28 is a generally tubular shaped member
having a necked down forwardly extended portion 42 integrally
connected to an enlarged elongated tubular rearward casing 40 by
means of an annular forwardly inclined intermediary wall 44. The
forward portion of the rearward casing 40 is radially undercut
providing an elongated radial joining surface 45 rearwardly
terminating with an exterior annular shoulder 46 which is adapted
to receive and suitably locate in a telescopic bonding manner the
inner radial surface and rearward end of the flare cup
respectively. The rearward casing 40 is further provided with an
internal annular shoulder 48 by means of a counterbore 50 disposed
at the rearward end of the rearward casing 40.
The necked down forwardly extending portion 42 is tapered at its
forward end as shown at 52 for engaging the inward concave area 27
of the flare pellet 18 as shown in FIG. 1. An inwardly radially
extending lip 54 is disposed at its rearward end thereof defining
an orifice 56 wherefrom the forward face 58 extends radially
outwardly and forwardly.
With reference now to the rearward end of the motor and delay
housing 28, the enlarged elongated tubular rearward casing 40 is
substantially closed by the transversely extending nozzle structure
30. The nozzle structure 30 is formed with an annular chamfer 60
around the rearward outer periphery thereof and is adapted to be
fixedly secured within the rearward end of the casing 40 by having
the end of the casing 40 swagged or deformed radially inwardly into
engagement with the periphery of the annular chamfer 60 as seen at
62 in FIG. 1.
The nozzle structure 30 is formed with a plurality of discharge
orifices (not shown) equally circumferentially and radially spaced
therearound. The function of the discharge orifices is to impart a
gyroscopically spin stabilized propulsion and guidance to the
rocket trajectory of the personnel distress signal 10. Reference
may be had to U.S. Pat. Nos. 3,490,121; 3,437,289; 3,419,230; and
3,367,112 assigned to the assignee of the present invention for a
disclosure of suitable nozzle and nozzle assemblies contemplated
for use in this invention.
The nozzle structure 30 is provided with a centrally located primer
or similar type ignition device which is fixedly mounted within a
suitable primer seat or opening 64 formed in the structure 30.
Extending across the interior or forwardmost side of the nozzle
structure 30 is a relatively thin, preferably rupturable, diaphragm
member 66 that is fabricated of a relatively thin sheet of aluminum
which may, for example, be secured to the forward side of the
nozzle structure 30 by a suitable pressure or heat sensitive
adhesive. The diaphragm 66 functions both as a hermetic seal for
the rearward end of the personnel distress signal 10, and to
facilitate pressure buildup internally of the motor and delay
housing 28 upon firing of the primer 64.
An annular recess 61 is provided slightly inward from the rearward
face of its nozzle structure 30 wherein an appropriate sealer such
as "humiseal" is disposed for the purpose of retaining the
propellant cartridge vapor at extreme temperature ranges. A second
type of sealer, such as phenol formaldehyde, is preferably used to
seal the primer 64 to the nozzle structure 30 as indicated at 63,
due to the corrosive action of "humiseal" on the primer 64. The
sealant at the joint where the motor casing 40 is swagged to hold
in the nozzle structure 30 indicated generally at 67 may be either
"humiseal" or phenol formaldehyde, or their equivalent.
Disposed within the rearward end of the casing 40 immediately
forwardly of the diaphragm 66 is the propellant spacer 32. The
propellant spacer 32 is comprised of an annular web portion 68
integrally engaged to a radial flange 70 having an outside diameter
preferably adapted to be snugly received within the counterbore 50
and suitably positioned by the annular shoulder 48. The annular web
portion 68 has a central aperture 72 and equal axial portions of
the radial flange 70 project from both sides of the web portion
68.
The propellant spacer 32 functions to separate the propellant
cartridge 34 from the nozzle structure 30, and to retain the
propellant cartridge 34 during propellant combustion. Because the
propellant spacer 32 is symmetrical axially from the web portion
68, it may be installed without regard to a rearward or forward
axial direction. Previous spacers which had to be referenced by a
forward or rearward end were often installed backwards, which led
to a malfunction of the personnel distress signal 10 during
operation. It will be appreciated that the nozzle structure 30
contains nozzle ports which would be covered by the propellant of
the propellant cartridge 34 if the propellant spacer 32 was
functioning improperly or was not present, whereby the covering of
the nozzle ports would hinder or prevent proper rocket
propulsion.
Further disposed within the rearward end of the casing axially
adjacent and forwardly from the propellant spacer 32 is a quantity
of propellant which may be of any suitable type known in the art.
In the preferred embodiment the propellant cartridge 34,
manufactured in spaghetti form, and guillotined to size for
insertion within the propellant housing casing 40. The propellant
cartridge 34 is generally cylindrically shaped having a central
bore or passage 73 disposed therewithin its central axis for the
purpose of receiving the propellant cartridge ignitor 36.
Preferably the outer diameter of the cartridge 34 is substantially
the same size as the inner diameter of the housing 28 whereby to
preclude any relative movement therebetween upon assembly of the
personnel distress signal 10.
The propellant cartridge ignitor 36 is disposed in the central bore
or passage 73 and comprised of a composition of a mixture of finely
ground (flour like consistency) 95/5 percent boron barium chromate
and a composition of granulated boron potassium nitrate mesh 12/20.
A combustion characteristic of boron barium chromate is a low gas
output whereas a combustion characteristic of Boron Porassium
Nitrate is a burning rate which is insensitive to combustion
pressure. This has been found to be very beneficial at low
environmental temperatures where the gas pressures are too low for
successful propellant combustion without the boron barium chromate,
while with high environmental temperatures the boron barium
chromate does not contribute sufficient gas pressures to cause
motor casing failure. Thus at low temperatures the heat requirement
of the propellant is satisfied by the boron potassium nitrate while
at high temperatures the propellant pressures are not increased by
the rate of boron potassium nitrate burn. Consequently, with the
use of boron barium chromate and boron potassium chromate in
effective combination there is obtained an ignitor composition,
which when combusted over the environmental extremes, delivers
sufficient heat to the propellant surface and generates suitable
chamber pressure so that propellant ignition is reliably
achieved.
With reference now to the necked down portion 42, located at the
forward end of the motor and delay housing 14, the delay train or
timing fuse 38 of pressed combustible material is disposed
therewithin.
The delay train or timing fuse 38 may be of any suitable material
adapted to burn at a preselected rate, whereby to function in
igniting the flare ignitor pellet 20 which in turn ignites the
flare pellet 18 at a preselected time after ignition of the
propellant cartridge 34, as will later be described. The rearward
face of the timing fuse 38 has a concave recessed portion 74
commencing slightly inward from the inside diameter of the
projecting lip 54 for the purpose of improving the containment of
the reaction products in the combustion zone, and also to assure
the complete burn of the timing fuse in a more certain manner. In
previous designs utilizing an oblate face, it was found that the
ignition of the delay train material produced conditions which
could cause a flaking off of the delay train material and result in
a cessation of combustion.
A second concave recess portion 76 is preferably similarly provided
in the forward face of the timing fuse 38 being generally larger
than the recess 74 in rearward wall. By manufacturing the forward
end in a similarly recessed manner, the heat from combustion in the
recessed area of the delay train is transferred to the flare
ignitor assuring reliable ignition.
In accordance with the principles of the present invention the
forward necked down portion 42 is provided with means adapted to
prevent the material of the timing fuse 38, which transforms to a
semi liquid state as it burns toward the flare pellet 18, from
being thrown or forced out of the rearward end of the necked down
portion 42 under the influence of centrifugal force due to rotation
of the personnel distress signal 10 during its forward propulsion.
The means is provided by the radially inwardly extending lip 54
which defines the centrally located restricted discharge orifice
56.
In the preferred construction of the present invention the
extending radial lip 54 encloses approximately one half of the
inside diameter of the necked down portion 42 with the result that
the diameter of the restricted orifice 56 is approximately one half
the inside diameter of the necked down portion 42. It may be noted
that the relative size of the necked down portion 42 with respect
to the diameter of the orifice 56 may be varied in accordance with
the type of material comprising the timing fuse 38.
From the above description, it will be seen that upon ignition of
the timing fuse 38, the extending radial lip 54 will prevent the
rearwardmost part of the timing fuse 38 from being forced outwardly
through the discharge orifice 56 as the personnel distress signal
10 rotates or spins while it is projected forwardly. Accordingly,
the timing fuse 38 upon being initially ignited, will burn smoothly
and continuously for a predetermined amount of time prior to
effecting ignition of the flare pellet 18, with the possibility of
a flameout of the timing fuse 38 being positively prevented.
A further preferred feature of the present invention is the use of
certain chemical coatings on designated areas of the personnel
distress signal 10 rocket to enhance the operational life of the
signal and surprisingly to contribute to the flare function.
Materials susceptible to deterioration when exposed to climate or
environmental conditions are used in the personnel distress signal
construction. These materials must be protected against such
deterioration to the extent that total rocket flare function is not
impaired. The protection in the form of a chemical coating useful
in the present invention has the added characteristic of not
cracking, chipping, or scaling with age, or extremes of climatic,
or environmental conditions.
"Humiseal" is a trademark of Columbia Technical Corporation for a
polyurethane which exhibits desirable properties for a continuous
use range from -70.degree. to 250.degree.F, is fungus resistant and
resistant to solvents. These characteristics are essential to a
flare rocket useful in any natural environment.
"Humiseal" is applied by dipping or spraying to the outside area of
the flare cup 16, and the flare cup motor assembly mating joint of
the skirt 24.
Another essential feature of the present invention concerns the use
of a paint coating by dipping or spraying on the flare cup 12 and
motor assembly-flare cup joint 45. The paint applied to the
personnel distress signal 10 serves two purposes. The first is to
provide environmental protection to the round. The second is
somewhat more subtle but equally important in that it retards the
spin rate thereby permitting increased burn time from the
pyrotechnic flare 12. As the motor assembly 14 burns and heats, the
paint on the surrounding casing 28 chars and forms bubbles. This
roughened surface reduces the spin rate after motor burnout prior
to flare cup ignition. This spin rate reduction occurs from both
the increased moment of inertia due to the bubbles as well as
increased aerodynamic drag. After flare cup ignition the spin rate
is even further reduced due to the heat produced by the burning
pyrotechnic. This continues the charring and bubbling action of the
paint. Because of this retardation effect on the spin rate, the
performance of the flare cup is greatly improved over the normal
performance achieved from a rapidly spinning payload.
Having now described the individual components of the personnel
distress signal 10, the components accordingly are assembled in the
following manner.
First the propellant cartridge 34 is washed and guillotined to
length. The necked down delay housing casing 42 is charged with the
timing fuse 38 by pressing with the delay composition. Propellant
cartridge 34 is inserted into the motor housing casing 28 followed
by propellant spacer 32. The propellant ignition charge 36 is then
loaded in the propellant passage 73. The nozzle structure 30 and
motor assembly 14 are then mated and the motor assembly 14 is
pinched or swagged over the nozzle structure 30. The flare pellets
18 are prepared. The "kraft" paper tube 26 is inserted into the
flare cup 16 and the flare pellets 18 are then inserted. The flare
ignitor 20 is then centrally placed into the exposed cavity 27 of
the flare pellet 18. The flare pellet 18 and flare pellet ignitor
20 are then compacted or pressed into the flare cup 16. The motor
assembly mating surface 45 is then coated with "humiseal" and the
motor 14 and flare assemblies 12 are mated. "Humiseal" is then
applied to the entire flare cup 16 and motor assembly flare cup
joint 45. The entire assembly is then painted for environmental
protection.
In operation of the personnel distress signal 10 of the present
invention, the distress signal 10 is adapted to be fired by, for
example, a hand held M207 Launcher or similar equipment having a
firing pin operable from triggering means.
With the barrel of the launcher oriented to a suitable angle for
accomplishing a desired trajectory, the triggering means of the
launcher is displaced which activates the firing pin forward
striking the primer 64. Upon explosion of the primer 64, the
diaphragm is ruptured and the propellant cartridge 16 ignitor 36
ignites, and consequently the propellant cartridge 34 is ignited.
At the same time the time fuse 38 of the delay train is
ignited.
The products of combustion of the propellant cartridge 34 vent
through the discharge orifices in the nozzle structure 30, driving
the personnel distress signal 10 from the launcher to a
predetermined altitude. The plurality of orifices, radially spaced
and angularly deposed in the nozzle structure 30, cause the
personnel distress signal 10 to spin or rotate about its
longitudinal axis imparting gyroscopic stabilization to the
distress signal 10.
Upon ignition of the timing fuse 38 of the delay train, the
material will begin to burn from the rearward end thereof toward
the forward end, with such material being transformed into a liquid
or semi liquid state due to the heat of combustion thereof. As
above described, the radially extending lip 54 prevents the liquid
portion of the timing fuse 38 from being forced out of the rearward
end of the necked down portion 42 of the motor and delay housing 26
as the distress signal 10 is rotating, thus assuring continuous
ignition of the timing fuse 38.
When the personnel distress signal has been propelled to a
predetermined altitude, the combustible material of the timing fuse
38 will be completely burned out and will ignite the flare pellet
ignitor 20 disposed in the concave recess 27 of the flare pellet
18. Ignition of the flare pellet ignitor results in ignition of the
flare pellet 18 which initiates a pyrotechnic display. The
pyrotechnic display is adapted to be sustained in the atmosphere
until the flare pellet and flare cup are consumed by the combustion
thereof.
While it will be apparent that the preferred embodiment of the
present invention disclosed herein is well calculated to fulfill
the objects above stated, it will be appreciated that the invention
is susceptible to modification, variation and change without
departing from the proper scope or fair meaning of the subjoined
claims.
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