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Патент USA US3086472

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April 23, 1963
J. J. TENNYSON
3,086,463
METHOD AND MEANS FOR INCREASING THE DRAG ON FALLING MISSILES
Filed Dec. 2, 1959
Tlql.
JNVENTOR.’
472mm J. Aha/W0”
BY
iinited States
B?dii?hd
Patented Apr. 23, 1963
1
2
3,086,463
coil from bombardment of the electron stream. The coil
13 may be a balanced Y arrangement as shown in FIG. 2.
METHOD AND MEANS FGR INCREASING THE
DRAG 9N FALLING MTSSILES
James E. Tennyson, 32 Brill Ava, Waterford, Qonn.
Filed Dec. 2, 1959, Ser. No. 856,879
‘3 Qlairns. (Cl. 102-3)
(Granted under Title 35, US. Code (1952), see. 266)
The coil is connected in circuit with a battery 14 and a
normally open thermal switch 15 supported near the lead
ing end of the missile; the switch is selected for closing
when its temperature rises to a selected level anticipated
during the fall of the missile through the atmosphere to
ward the earth. The battery may be any of the batteries
The invention described herein may be manufactured
providing a good ratio of power output to weight and size.
and used by or for the Government of the United States 10 The battery is required to provide power for only a very
of America for governmental purposes without the pay
brief period. No resistance element is included in series
ment of any royalties thereon or therefor.
with the battery since it may be operated at substantially
This invention relates to increasing the drag on mis
short circuit during its duty period. The duty period of
siles falling toward the earth at high speed. The term
the battery need not be coincident with the entire interval
missile is used in a broad sense and relates to a nose cone 15 of excessive temperature. lf eifective even for only a
portion of a missile, or to a rte-entering satellite, and to
fraction of that interval any disintegration that might oc
other man-made space traversing bodies that have a for
cur is reduced. The magnetic ?eld need not be the only
ward end and a trailing end when falling.
expedient relied upon for resisting disintegration. Dis
An object of this invention is to reduce damage due to
integration is resisted by a heat sink design or by con
aerodynamic friction on a missile moving at high speed 20 trolled ablation at the leading end. This invention con
through the atmosphere.
tributes toward decreased disintegration. The broken
A further object is to minimize the disintegration of a
lines ‘16 illustrate the paths of electrons that escape from
missile on the return portion of its trajectory.
the leading end of the missile and form a trail behind the
Other objects and many of the attendant advantages of
falling missile.
this invention will be readily appreciated as the same be~ 25
The forward end of the missile, in the direction of fall,
comes better understood by reference to the following de
may include a surface layer of a material with a low
tailed description when considered in connection with the
thermionic work function, e.g., a magnesium alloy so that
accompanying drawing wherein:
electron evaporation may take place at a temperature
FIG. 1 illustrates an embodiment of this invention on
which is substantially lower than that at which the missile
30 deteriorates.
a missile, and
FIG. 2 illustrates a circuit arrangement for the mag
Where the embodiment illustrated in FIG. 1 is a nose
netic ?eld generating means.
cone, the struts and coil are included within the propul
This invention utilizes the fact that an electron can be
sion stage until the latter drops o?‘.
driven off a body of solid material by supplying enough
In operation, when the nose cone is on its return path
energy instantaneously to that electron to overcome the
toward the earth and approaches the more dense atmos
forces constraining the electron to remain within the ma
phere, aerodynamic friction causes heating which is most
terial; Work function refers to the quantity of energy re
pronounced at the leading end. Electron evaporation
quired by the electron to enable it to escape. The energy
may be supplied thermionically, photoelectrically or in
from the surface at the leading end becomes appreciable
other forms. Substantial quantities of electrons can be
driven or evaporated from a body in this manner. This
effect is most commonly utilized in thermionic electron
tubes; it is utilized in this invention.
at velocities on the order of several kilometers per second
Solid bodies traveling through the atmosphere at hyper
sonic speed leave an ionic trail.
In Journal of Applied
Physics, November 1957, Partridge and Harris report the
measurement of electron density in the trails of high ve
locity pellets of between 101° and 1015 electrons per centi
meter of path for velocity ranges of 1.0-4.5 kilometers
per second and also report the relative velocities at which
aluminum, magnesium, and magnesium~lithium alloy
leave ionization trails. ‘In the same edition of the Journal,
Hendricks reports the measurement of electron density of
between 109 and 1013 electrons per centimeter of path
length for pellet velocities ranging from 1.48 to 2.67 kilo
meters per second. These reports clearly indicate that an
electron trail is left by high velocity missiles. Energy
transferred to the outside surface of the missile as a re
as the temperature rises.
The evaporated electrons will leave the coating material
and will come to rest ‘after one or more violent collisions
with molecules of oxygen and nitrogen of the atmosphere
where the mean free path is on the order of one to ten
centimeters at pressures of 10*6 to 10*7 of the pressure
at the earth’s surface. This information is published in
Radio Astronomy by Lovell and Clegg published by John
Wiley and Sons. The magnetic ?eld generated by coil 13
when the thermal switch 15 is actuated is drawn through
the ‘arrested electrons at the missile velocity.
When the leading end of the missile rises above the
actuation temperature of switch 15, the switch closes and
connects the battery to the magnetic coil arrangement 13
which in turn generates a magnetic ?eld transverse to the
direction of travel. The magnetic ?eld moving with and
just behind the missile is drawn through the evaporated
and arrested electrons at the velocity of the falling missile.
This results in a. drag on the falling nose cone.
sult of aerodynamic friction produces electron evapora
As the magnetic ?eld moves through the trail of elec
tion and the electrons are left behind by the moving mis— 60 trons there is generated an electric ?eld perpendicular to
sile.
both the direction of electron flow and the direction of
In its broader aspects this invention concerns generat
the magnetic ?eld. This electric ?eld in turn produces
ing a magnetic ?eld locally at the trailing end of the mis
an electric current in the same direction as the electric
sile transverse to the path thereof when falling toward the
?eld. The quantity of electric current is dependent upon
earth for interacting (with the trail of electrons to affect 65 the conductivity of the ?uid. From information pro—
a drag on the falling missile.
vided in The Physics of Fully Ionized Gases by Spitzen,
The missile 10 shown in FIG. 1 includes a pair of rigid
page 84, equation 5-37, if the number of electrons per
struts l1 and 12 at its trailing end. A rigid magnetic ?eld
cubic centimeter is conservatively estimated to be 1012
coil 13 is secured to the struts l1 and 12. The coil 13
and the temperature is estimated to be ‘~1000° K., the re
70
consists of a high conductivity metal coated with a high
sultant conductivity is 100 mh-os/meter. This current in
work function material such as platinum to protect the
turn reacting with the magnetic ?eld, creates a mechanical
3,086,463
3
4
force or induction drag which acts opposite to the direc
tion in which the missile is moving, thus tending to re
duce the speed of the missile. Assuming at a particular
instant that the velocity is 5 kilometers per second and
the magnetic induction is 0.5 Weber per square meter, the
magnetic viscous force opposing the missile is as follows
m-al to the axis of the missile and interacting with the ion
trail vfor exerting a drag on the falling missile.
2. A method of reducing the disintegration of the nose
cone of a missile passing through the atmosphere at hyper
sonic speeds with resultant emission of a trailing stream
of conducting ?uid, which comprises creating a substan
tially constant continuous magnetic ?eld in the wake of
and normal to the direction of travel of the missile to
intersect the trailing stream of conducting ?uid to in
where F=force per unit volume.
10 crease the drag on said missile.
3. The method of reducing the disintegration of a body
Since one newton is equal to 0.25 pound in gravita—
while moving at hypersonic speeds in the atmosphere,
tional units, the induction drag for the assumed condi—
which comprises providing on the exposed surface of said
tions is 62,000 pounds, which is signi?cant even if applied
body, a layer of a material which emits a high density
for only a small fraction of the anticipated time interval
during which the temperature level may tend to deteriorate 15 stream of electrons when its exposed surface is heated to
temperatures created by such speeds, and creating a sub
the leading end of the missile. However, it is important
stantially constant continuous magnetic ?eld in the wake
to bear in mind that even less drag or slowing effect will
of and normal to the direction of travel of the body to
tend to reduce deterioration even if applied for a brief
period.
intersect the trailing stream to exert ‘a drag on said body.
following exhaustion of the propellant.
moving with said body for creating in said trailing stream
Obviously many modi?cations and variations of the
present invention are possible in the light of the above
teachings. It is therefore to be understood that within the
scope of the appended claims the invention may be prac
ticed otherwise than as speci?cally described.
in the wake of said missile local to and external to said
body a constant magnetic ?eld oriented generally normal
to the missile axis, for at least part of the time that the
4. An improved missile capable of falling at hyper
Alternate methods of construction may include making 20
sonic speeds through the atmosphere which comprises a
the ?eld coils an integral part of the missile body using
body having on its nose an exposed surface of a material
small coils but of greater length or providing magnetic
which emits a trailing stream of electrons when heated
coils and supporting struts that may be folded back while
to temperatures created by said speeds, and means dis
launching and in initial ?ight but released into position
by a frangible element ruptured by an explosive charge 25 posed rearward of and exterior to and carried by and
missile falls and that by interaction of said magnetic ?eld
with said trailing stream exerts a drag on the falling move
ment of said body.
References Cited in the ?le of this patent
through the earth’s atmosphere toward the earth for the
UNITED STATES PATENTS
35.
purpose of reducing the disintegrating effect of aerody
2,431,319‘
Ellwood _____________ __ Nov. 25, 1947
namic friction, where the missile is of the type that has a
2,555,384
Watt _____________ __,____ June 5, 1951
particular part that is at the trailing end during its fall,
2,850,978
Franklin __> ___________ __ Sept. 9, 1958
and where the missile leaves an ion trail during its fall,
2,882,824
Larsen ____________ _____ Apr. 21, 1959
which comprises generating a local substantially constant
2,921,518
Huntoon _____________ .._ Jan. 19, 1960
magnetic ?eld rearward of and exterior to the trailing end
part of the missile and exposed to and intersecting any
OTHER REFERENCES _
?uid medium in the wake of the missile during at least
Physics, Part II (Halliday and Resnick), published by
part of the time that the missile is falling and is leaving
John Wiley & Sons Inc., '1960' (pages 689 and 690
an ion trail and which said magnetic ?eld moves with the
trailing end of the missile, ‘and is oriented generally nor 45 relied on). (Copy in Div. 10.)
I claim:
1. A method of increasing the drag on a missile falling
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