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Патент USA US2408358

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Sept-124,- ‘1946-
w. w. WILLARD
I '' 2,408,356
SIGHTDING MECHANISM
Filed March- 20, 1931
.
{Sheets-Sheet 1
Inventor-*5
Waldo W. Willar‘d,
‘
Sept. 24, 1946.‘ '
w. w. WILLARD =
'
SIGHTING
MECHANISM
Fl‘iled March 20, 1931
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Sept. 24,1946,
w. w.‘ WILLARD
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2,408,356
SIGHTING ‘MECHANISM
Filed Mar-ch 20, 1931
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inventor“:
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Waldo W. Willard,
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Sew-24.1946
w. w. WILLARD
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SIGHTING MECHANISM
Filed March 20, 1931
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Patented Sept. 24, W46
UNITED STATES PATENT OFFICE
2,408,356
SIGHTING MECHANISM
Waldo W. Willard, Schenectady, N. Y., assignor to
General Electric Company, a corporation of New
York
Application March 20, 1931, Serial No. 524,193
'
57 Claims.
(cl. 33—46.5)
2
My invention relates to sighting mechanism
indicator.
and the like, more particularly to sighting mech
automatically to give a signal or to release the
bomb when the airplane reaches a position from
anism for directing a projectile on a target, for
example in the
ratus, etc., and
of an improved
My invention
control of guns, bombing appa
has for its object the provision
mechanism of this character.
has special application to sight
which a hit can be made.
More speci?cally, in one form of my invention
I provide a suitable gyroscope connected so that
by its precession it will move the sighting device
about predetermined axes, as for example, the
fore and aft axis of the airplane and another at
ing mechanism for controlling the dropping of
bombs from airplanes or other aircraft, and a
further object is the provision of reliable and ac
curate means for directing the pilot to steer the
attacking airplane to take a collision course, i. e.,
10
athwartship. In order to maintain the sighting
of a bomb from the airplane at the proper in
stant of time; and further, for determining the
proper instant of time at which the bomb should
be released in order that the bomb will arrive at
the same point as the target at the same instant
of time and thereby score a hit.
20
In one of its aspects, my invention contemplates
. attacking airplane will direct the pilot as to how
he must steer the attacking airplane so as to ar
right angles thereto, the latter lying generally
device on the target, I provide suitable means for
applying to the gyroscope a measured torque con
trolling the precession of the gyroscope so that
the rate of precession is such as to maintain the
such a course with respect to a target or like
object that a hit will be secured upon the release
the provision of sighting mechanism which will
measure continuously the apparent linear speed
of the target, and also the apparent relative di
rection of its course; and which with the knowl
edge thus obtained and with the known data with
respect to the altitude and the air speed of the
Thereafter the mechanism operates
sighting device on the target.
I have further provided suitable means for
measuring the range angle of the bomb, prefer
ably in terms of its fore and aft and athwartship
angular coordinates, and for measuring continu
ously, as the battle action progresses, the angular
position of the target with respect to the airplane,
preferably in terms of its fore and aft and
athwartship angular coordinates, and for com
paring continuously these measured coordinates
with the corresponding measured coordinates of
the range angle of the bomb. It will be observed
that when these former angular coordinates have
by the progress of the battle action become equal
rive at a collision course; and furthermore, deter 30
to the latter each to each at the same instant
mine the proper time for releasing the bomb so
of time, it is the proper time to effect the release
that a hit may be scored.
of the bomb. Suitable means is provided for
In carrying out my invention in one form, I'
effecting the automatic release of the bomb when
provide mechanism in which certain known quan
this condition exists, or if desired, a suitable sig
titles are introduced and which thereafter oper
nal can be given that the proper time for release
ates to compute the collision course and the cor
, of the bomb has arrived.
rect point in this course at which the bomb must
The pilot directing mechanism whereby the
be released to score a hit. In its simplest aspects
pilot
will be instructed as to how he must steer
the mechanism comprises a sighting device to
the airplane in order to arrive at and stay on a
gether with means for continuously moving the
collision course so that a hit may be scored in
sighting device so as to maintain it on the target
one form of my invention comprises suitable
and thereby generate the apparent linear speed
means for measuring continuously, as the battle
and relative direction of movement of the target
action progresses, the instantaneous magnitudes
and apply these quantities to the associated
of the bearing of the target with reference to a
mechanism. The altitude and air speed of the
attacking airplane as determined by suitable
devices are also introduced into the mechanism.
A course indicator for the pilot of the airplane
is provided, this indicator being operated auto
matically by the apparatus so as to indicate a col
lision course. In its operation, the mechanism
is adjusted to move the sighting device continu
ously with the target, the altitude and air speed
having been introduced, and the pilot directs the
predetermined axis, which preferably will be the
fore and aft axis, and further, suitable means
for measuring the instantaneous magnitudes of
the direction angle of the apparent course of the
target with respect to this predetermined axis.
The instantaneous magnitudes of the bearing and
of the direction angle are continuously compared
during the course of the battle action and their
oustanding differences indicated to the pilot.
For a more complete understanding of my in
airplane on a collision course as shown by his 55
vention reference should be had to the accom
2,408,356
3
4
when discussing the problem in two dimensions
panying drawings in which Fig. 1 is a diagram
I have chosen as the point of origin a point on
the ground or water level or at the height of the
matic perspective View illustrating the attacking
airplane and the ?eld of action, it being assumed
target and vertically below the sighting instru
that the airplane is the reference point, and be
ing the reference point, has no motion in the sys
tem of coordinates chosen but that the target has
ment, and the axes are, the horizontal fore and
aft axis OX, the horizontal athwartship axis OY,
and the vertical axis 025. Thus, in the diagram
of the ?eld. of action (Fig. ‘1), tneorigin O and
all of the motion it seems to have when viewed
from the airplane, and illustrating the various
the horizontal axes OX and OY are‘shown as
elements of the bombing problem shown quan 10 though they were on the ground or water level.
titatively as they appear at the instant of release
It is to be understood, however, that the origin
of the bomb; Fig. 2 is a diagrammatic view of the
0 and the horizontal axes may be located in an
field of action illustrating the attacking airplane
elevated plane parallel with the tangent plane
in several positions in its approach to a collision
course, it being assumed in this figure that the
target being the point of reference, has no motion
in the system of coordinates chosen but that the
airplane has all of the motion it seems to have
when viewed from the target; Fig. 3 is a perspec
tive view of a sighting device, together with cer
to the earth’s surface.
It is assumed that the coordinate axes OX, CY
and OZ move and turn with the airplane. How
ever, while the whole system of coordinates moves
with the airplane through the air, the system does
not tilt with the airplane. In other words, the OZ
axis remains vertical and the plane containing
tain operating and auxiliary apparatus arranged 20 the OX and OY axes remains horizontal.
The speed of the target is computed with rela
in accordance with my invention; Fig. 4 is a dia
tion to the airplane; and this speed is the re
grammatic view which taken with Fig. 3 illus
trates a bomb sight mechanism embodying my in
vention; Fig. 5 is a diagrammatic view illustrat
ing a bomb releasing circuit comprising certain
controllingswitches therefor, which switches are
arranged and controlled in accordance with my
invention; Fig. 6 is an elevation of a portion of
, the bomb sight mechanism of Figs. 3 and 4 taken
on the line 6——5 of Fig. 4; Fig. 7 is an elevation
sultant of the target’s own motion and the mo
tion of the airplane. The motion of the air
plane is the resultant of its motion due to its
own propulsive force and its motion due to wind
age. Likewise, the motion of the target is the
resultant of its motion due to its own propulsive
force and its motion due to windage or water cur
30 rents. All of these variables are included, it will
of a portion of the bomb sight mechanism of Figs.
3 and 4 taken on the line 'L-‘l of Fig. 4; Fig. 8
is a pilot indicating mechanism and control
therefor arranged in accordance with my inven
tion; Fig; 9 is a diagrammatic representation of
a preferred system for transmitting angular mo
"tion used on the bomb sight mechanism of Figs.
3 and 4; Fig. 10 is a graphic representation of
certain factors involved in the problem of deter
mining certain altitude scales shown in Fig. 11
and used in the bomb sight mechanism of Figs.
3 and 4; and Fig. 12 is a graphic representation
of certain factors involved in the problem of de
termining certain altitude scales shown in Fig. 13
and used in the bomb sight mechanism of Figs. .
3 and 4.
Referring to the drawings, I have shown my
invention in one form as applied to sighting
mechanism intended to be used in connection
with bombing apparatus for airplanes and like
aircraft. Referring more particularly to Figs. 1
and 2, I have illustrated diagrammatically the
general problem involved in bombing operations.
that the problem is to drop
be observed, in the observations given the speed
of the target with relation to the airplane. The
motions of the airplane and target with relation
to the earth are immaterial, except that the alti
tude of the airplane, of course, enters into the
‘calculations.
Referring to Fig. 1, it will be understood that
the airplane is assumed to have no motion in the
system of ‘coordinates chosen and that the only
motion is that of the target and the bomb with
respect to the airplane. At the instant the bomb
is released, the target is at the position marked
“target’s position at release.” The target moves
along the line indicated “target’s apparent motion
during time of flight of bomb” while the bomb
is dropping, and the bomb is dropped so as to
arrive at “the point of impact” at the same in
stant of time as the target and thereby score a
t.
It will be observed that “the point of impact”
is some distance back along the OX axis from
the origin 0. The reason for this is as follows:
The bomb will have the same speed, of course,
as the airplane at the instant of release and con
' It will be understood
a bomb from an airplane upon a moving target, 55 sequently will continue to travel forward as it
such as a battle ship, a train, etc. It is contem
drops. However, the bomb will not continue to
plated, of course, that the target may be station
ary; but in the example illustrated the target is
assumed to be moving. Moreover, it is assumed
travel forward at the same speed as the air
plane because of the effect of the air motion
caused by the propeller, or in other words, be
60
that the target is moving in a ?xed plane, as for
cause of the effect of the pressure of the slip
instance, the plane of the earth. However, it is
stream. As has been pointed out, the coordinates
to :be understood that the target may be moving
chosen are referred to a point of origin on the
through the air in a plane parallel with the
airplane and consequently all air motions other
earth’s plane; thus, the target may be an airplane
than that caused by the propeller, directly back
65 along the OX axis, carry the airplane, and hence
or some other form of aircraft.
The problem is solved from the aviator’s point
the coordinates with them. The effect of this
of View. The airplane rather than any ?xed point
propeller wind is known as “trail.”
on the earth is chosen as the reference point.
In other words, suppose that the airplane due
‘ Therefore, the problem will be discussed in such
to its own propulsive power is travelling forward
mathematical terms as are presented to the senses
straight ahead along the OX axis. Under these
of' the bomber and pilot. The problem when
conditions it may be assumed that the airplane is
treated in three dimensions will be discussed in
standing still and the air current which is due
terms of polar coordinates referred to a point
exclusively to the propeller, is blowing from
of origin on the airplane which point preferably
straight ahead. As has been pointed out, Fig. 1
will be the location of the sighting telescope; but 75
‘2,408,356
' 6
illustrates this set of conditions. "There is no
'motion of air athwartship with respect to the
' airplane or bomb because the airplane, the bomb,
and the coordinates chosen arecarried along
with any such air movement. Therefore, the only
two forces to be accounted for as acting on the
bomb in dropping are the force of gravity and
that of the air moving back along the OX axis;
and in consequence, the bomb travels back along
The o?set for “trail” is a known function of alti
tude, apparent wind at the airplane and the type
of bomb.
'
For convenience the apparent target speed will
be resolved into two components oblique to each
other, one the effect of the air speed of the air
plane and the other the effect of the apparent
Wind at the target. The sight offset also will be
resolved into two components, one fore and aft
the OX axis as it drops toward the earth, its
and the other athwartship.
“trajectory” being wholly in the X—Z plane.
Referring to Fig. 1 and bearing in mind the
This distance that the bomb travels back along
elements which must be considered, it will be
the OX axis, 1. e., “trail,” is the distance along
understood that the vector WT representing wind
the OX axis of “the point of impact” from the
times the time of ?ight of the bomb relates'to
vertical OZ axis.
15 the apparent wind at the target. The apparent
It is to be understood that for a given set
motions of the ground need not be considered
of conditions with respect to the altitude and air
since, as has been pointed out, the action is
speed of the attacking airplane, the “trail” for
between the attacking airplane and the target
a given bomb and releasing mechanism will be
only. Thus, the true wind and the true target
a ?xed distance directly back along the OX axis, 20 speed may be combined as a single vector, i.-e.,
and consequently “the point of impact” bears
apparent wind at the target.
‘ '
a ?xed relation with respect to the airplane pro
The resultant of the wind‘ vector WT and a
viding the altitude and air speed remain con
vector ST representing the air speed of the air
stant. In the following discussion, therefore,
plane times the time of ?ight of the bomb repre
the airplane and “the point of impact” will be
sents the total motion of the airplane relative to
considered to be a ?xed system, “the point of
the target during the time of ?ight or in other
impact” of course being located in the horizontal
words, this resultant reversed represents the to
plane in which the target is moving.
tal motion of the target during the same time in
It will be understood in the light of the above
the system of coordinates chosen. Since this vec
discussion that the bomber has two separate
tor will, in fact, represent the total target speed
problems: (1) To cause the target to approach
in the system times the time of ?ight, the vec
along a path such that it will pass through “the
tor will also represent the total motion of the
point of impact,” and (2) To determine a point
target during the interval from release to im
along this path of the target’s motion such that
pact, and must joint the positions occupied by
if the bomb is released when the target is at
the target at these two instants of time.
this point, the bomb will make connections with
It will be understood that the resultant of the
the target at “the point of impact” and thereby
wind vector WT and the airspeed vector ST, i. e.,
score a hit.
the total motion of the target during the time
It is to be understood that with such a sys-.
of ?ight of the bomb, or in other words the linear
tem of coordinates as are chosen in Fig. 1, the :1 olTset for apparent target speed, may be cal
elements of the problem that necessarily will be
culated directly by measuring the angular ap
considered are: The apparent target speed; and
parent speed of the target in the system of co—
the time of ?ight of the bomb. The apparent
ordinates chosen converting it to linear speed
target speed is the resultant of two components:
and multiplying the speed thus converted by the
one the effect of the apparent wind at the target,
45 time of ?ight of the bomb. The offset for‘ trail,
' and the other, the effect of the air speed of the
as has been pointed out, may be determined read
airplane. The apparent wind at the target, in
ily from the known data with respect to the alti
turn, is the resultant of two components; one the
tude and the airspeed of the airplane. Therefore,
e?ect of the target’s own speed, and the other
with the known data with respect to the altitude
the effect of true wind. By “true wind” is 50 and airspeed of the attacking airplane and with
meant the existing wind relative to a ?xed point
the observable datum with respect to the target’s
on the earth.
'
angular apparent velocity su?icient information
The apparent wind at the target and apparent
will be had to determine the proper sight o?'set,
target speed are directed quantities and will,
which as has been pointed out, is the resultant of
therefore, be represented as vectors. The latter 55 the offset for trail and the offset for apparent
target speed.
of these two quantities is directly observable.
The time of ?ight for a particular type of bomb
More speci?cally, therefore, the problems which
is a known joint function of the altitude and
are presented to the bomber are to determine
the effect of the pressure of the slip stream, or ‘
‘from the known data with respect to the altitude
in other words, the eifect of the apparent wind 60 and the air speed of the airplane the distance
at the airplane or the air speed of the airplane,
back along the OK axis of “the point of impact,”
assuming, of course, that the bomb is always
it being understood that the magnitude of this
released in the same manner. It will be under
distance remains constant for constant condi
stood that for the present problem the slight
tions with respect to the altitude and air speed
effects upon the time of ?ight of variations of 65 of the airplane; to measure the target’s angular
air density from the mean annual Value, the rate
velocity and from that to deduce its total motion
- of change of altitude, of the latitude of the place,
during the interval of time measured by the time
etc. may be neglected.
of ?ight of the bomb, and to determine the ap
In general, therefore, the linear sight offset
parent direction of that motion and the direction
can be represented completely by the resultant of
and distance of the target from “the point of
two vectors, viz; Offset for apparent target speed,
impact”; and with the known data with respect
and offset for “trail.” The offset for apparent
to the location of “the point of impact,” and the
- target speed is the product of the apparent target
target’s direction and the apparent direction of its
- speed by the time of ?ight of the bomb and is
motion to instruct the pilot to fly the airplane in
opposite in direction to the apparent target speed. 75 such a direction that “the point of impact” will
‘2,408,356
7
the 'fore and aft and athwartship axes so ‘as to
be carried on a collision coursei and further, with
the calculated data with respect to the location of
“the point of impact” and the target's total ‘mo
tion during the time of ?ight of the bomb' to effect
the release of the bomb at such ‘a time that the
bomb will arrive at “the point of impact”-at the
same instant as the target.
7
In solving the bombing problem chosen cer
tain elementary quantities must be considered.
maintain it on the target, the angular position
and velocity of the target, of course, with‘rela
tion to the airplane, being thereby measured
about these axes.
_
The telescope is mounted rigidly in a suitable
frame (not shown) and the line of sight is kept
bearing on the target by means of a, mirror or
prism ll located in front of the objective l2. It
will be observed that the telescope looks ‘into the
. For convenience, these are tabulated immediately 10 mirror along a line parallel to the axis fore and
below since they will occur frequently in the T01
lowing discussion and description of the sight.
X is the distance the target is ahead of the
aft. As'will be described in detail the mirror is
mounted in a gimbal type mounting that allows
airplane.
paratively large solid angle. One axis of this
'gimbal system is parallel to the fore and aft axis
it to move freely in all directions through a com
Y is the athwartship distance of the target, in
the problem chosen to the right of the airplane.
OX of the airplane and the other swings in a
h is the altitude, i. e., the height of the air
vertical plane, parallel to its athwartship axis
plane above the plane in which the target ‘is
OY,‘ i. e., swings in the YZ plane.
moving. (It is taken as unit distance When reck
It is desirable that the fore and aft and
oning trigonometric functions of angles at the. 20 athwartship components of the target's apparent
origin.)
angular velocity be measured by some means
S is the airspeed of the airplane.
that will yield the knowledge of its present angu
W is the apparent wind at the target.
lar rate at the present instant of time, i. e., the
It
is
T is the time of ?ight of the bomb.
vinstantaneous values of its apparent angular
taken as unit time.
velocity. In order to‘ bring about this result I
a is the angular distance the target is ahead of
have taken advantage of the inherent charac
the airplane projected onto the vertical fore and
teristic of a gyroscope whereby if its spin speed
aft plane.
be kept constant its angular rate of precession
{3 is the athwartship angular distance of the tar
will be proportional to the instantaneously meas
get (in the problem chosen), to the right of the 30 urable torque couple which is applied to cause
airplane.
the precession.
Range forward is the distance the target is
The mirror or prism II is connected mechani
ahead of the airplane at the time of release of
cally to a suitable gyroscope [3‘ so as to cause
the bomb.
the line of sight to move with the gyroscope about
Range athwartship is the distance the target 35 axes parallel and adjacent to its gimbal axes
is to the right (in the problem chosen) of the
which are the fore and aft axis OX and another
airplane at the time of release.
at right angles thereto, the latter lying generally
Trail is the distance the impact occurs behind
athwartship, and the line of sight is moved to
the airplane.
' '
maintain it on the target by applying torques to
4.0
01.1‘ is the range angle or sight offset ‘forward,
the gyroscope to cause the necessary precession
i. e., the angle subtended at the origin 'by the
to adjust the mirror or prism. Since the target
range forward, or the value as must have ‘at the
is moving with relation to the airplane the mirror
instant of release.
or prism must be given a corresponding motion.
Br is the range angle or sight offset athwart
As has been pointed out, the mirror H is the
ship, i. e., the angle subtended at the origin by
element of the telescope which is connected with
the range athwartship, or the'angle 5 must ‘have
the gyroscope. The gyroscope movement is-ap
at the instant of release.
plied directly to the mirror about the fore and
0 is the angular distance the ‘target is ahead
aft axis OX, but about the axis at right angles
of the airplane, measured in the oblique plane
‘to OX the mirror is given but one half the angle
that contains the target and the fore and aft line _
of movement of the gyroscope since-the angular
of the airplane.
movement of the line of sight about this axis is
in is the angle made by the vector W and the
equal to twice the angular movement of the
fore and aft axis OX. That is, .the relative direc
mirror. This is accomplished by mounting the
tion of the apparent wind at the target.
‘mirror in a gimbal type mounting that allows
4% is the angle between a straight line joining
it to move freely in all directions throughout a
the target and “the point of impact,” and the
comparatively large solid angle, and a suitable
fore and aft axis OX. It is the relative bearing
linkage mechanism.
of the target from “the point of impact.”
As shown, the mirror is mounted for rotation
¢' is the angle between the apparent direction
of the course or of the path of vmotion of the tar- ,7
get and the fore and aft axis OX.
The quantities on, p, and 0 are shown'in‘Fig. l
at the values they assume at the instant ‘of re
lease. It'is to'be understood, however, 'that'they
are the general values of ‘the ‘variables as de?ned.
As has been pointed out,‘ the known ‘data are
the altitude and the air speed of the airplane,
while the observable data are the-‘angular posi
tion and apparent angular velocity of the target.
The angular positionfand velocity of the target
are determined by means of a telescope it] (Big.
3) mounted in the attacking airplane. The
angular position and velocity are determined
simply by moving the line ‘of sig‘ht‘of the tele
Pscope about predetermined axes, as tor example,
' about its variable axis by means of a pair of pro
jecting stud-like shafts M which are mounted for
rotary movement in bearings provided for them
in a suitable forked supporting member If). This
forked member is rigidly secured to the fore and
- aft gimbal axis It or the gyroscope and conse
quently imparts the gyroscope’s angular move
ment about the fore and aft axis to the mirror.
The gyroscope’s angular movement about the
variable axis at right angles to OX is transmitted
to rotate the mirror about its variable axes M
by means of a link connection whichimparts to
the'mirror but one half of'this component of the
gyroscope’s angular movement. This connec
tion comprises an angle dividing mechanism in
cluding a link 20 secured at its upper end to one
2,408,356
end of a shaft 2! which is mounted for rotation
in a bearing support 22' ‘rigidly secured to the
gyroscope’s fore and aft gimbal axis [6. The
opposite end of this shaft 2! is mechanically
course for a hit, the target has or is assumed to
have, uniform linear apparent motion when
viewed from the bombing plane. As has been
pointed out, in order that the line of sight may
connected to one of the mirror supporting shafts
14 by means of a pair of cranks 23 and 24 of equal
length, each secured at one end to one of the re
stay on the target, it is necessary that the spin
axis of the gyroscope should execute such angular
motions that it points continuously in the direc
tion of the target. It is desirable that suitable
means be provided for automatically controlling
spective shafts 2! and id, and'a link 25 inter
posed between and mechanically interconnecting
the free ends of these cranks. It will be ob 10 the motion of the gyroscope so that once its mo
tion has been adjusted to point continuously to
served by reason of this connection that the
the target, the adjustment need not be changed
mirror will always follow the angular movement
subsequently as the battle action progresses.
of the link 20, i. e., the mirror will always be
The angular rate of precession of a gyroscope
rotated through an angle equal to the angular
is:
movement of the link 28. The gyroscope’s move
KTo. secant 60
ment about its variable axis at right angles to
OX is transmitted to the link 28 by means of a
in which
'
link 26 pivotally connected at its upper end to
K is a machine constant related to the dimen
the forked support I5, and mechanically con
sions of the gyroscope and its spin speed,
nected at its lower end to the lower portion of 20
To is the torque applied to some axis of the
the vertical gimbal ring l3a of the gyroscope by
gimbal system to cause precession of the gyro
means of a link 2611. The link 26 has the same
‘length as the radius from the center of the gyro
scope, and
0a is the complement of the angle made by the
scope gimbal system to the point of attachment
axis of the torque T0 with the spin axis of gy
of link 26a, and is mechanically interconnected 25 roscope, and is measured in the plane, generally
to the lower end of the link 29 by means of a
oblique, that contains both the axis of torque To
pin and slot connection 21. The pin for this
and the spin axis.
connection is located at a distance from the
If the apparent motion of the target is uni
pivotal axis of link 26 on forked member l5 equal
form along a line parallel to the axis of the
to the distance of that pivotal axis from the 30 torque To, the angular precession rate required
center of shaft 2!. It will be apparent that by
is:
'
reason of this arrangement the link 29 and con
Ig-cos2 00
sequently the mirror l I will be moved through
but one halfxof the angular movement of the
gyroscope about its variable axis at right angles 35 in which
V0 is the linear apparent velocity of the target,
and h is the perpendicular let fall on the target’s
apparent path from the bombing plane.
'
tions between the gyroscope l3 and the mirror
It
is
to
be
noted
that
in
thepreceding
discus
9 l gives the mirror such relation to the gyroscope
that the line of sight of the telescope i0 is always 40 sion, V0 is the total or resultant linear velocity,
and To is the total or resultant torque. - '
maintained parallel to the spin axis of the gyro
As soon as the airplane has arrived at the right
scope. It will also be observed that in order to
to OX.
It will be observed that the linkage connec
keep the line of sight on the target it is only nec
essary to keep the spin axis of the gyroscope
pointing at the target, and in order to know the
angular rate of the apparent motion of the target
course for a hit, it may be assumed without ma
The gyroscope spin axis when once pointed at
the target will continue to point to the target by .
reason of its inherent characteristic except for
following equation:
terial error, for the purpose of establishing the
relation of precession torque to linear apparent velocity, that the apparent path of the target to
“the point of impact” lies directly below the bomb
it is only necessary to know the rate at which
ing plane, rather than to one side or the other in
the spin axis is changing its direction. It will
accordance with the effect of “trail” as shown
‘be understood that the gyroscope is in neutral
‘suspension so that it is free to move relative to 50 in Fig. 1. With this assumption in mind, it will
be observed that h is merely the altitude of the
its frame. Its spin axis, therefore, will retain
bombing plane.
whatever direction it has irrespective of the roll
It will be apparent therefore, that we have the
ing, pitching, yawing or turning of the airplane.
the apparent motion of the target. Thus, in order
to keep the spin axis pointed at the target in spite
of the target’s motion it is necessary to process
the gyroscope in the direction of the target’s ap->
parent motion and at the angular rate of that
motion. This necessary precession is brought
about by applying to the gyroscope a measured
resultant torque in a plane through the spin
axis and containing the line of the desired mo
tion.,
Preferably, this torque will be measured and
applied in two component parts, one of which
'
w-cosz 90: KTO sec 00 .
Solving for To, we have:
It To and V0 now be regarded as resultant di
rected quantities with horizontal components TX
and Ty, and VX and Vy, respectively, chosen in
order parallel and perpendicular to the fore and
aft axis OX of the bombing plane, each com
ponent of torque will be related to the correspond
ing component of velocity as follows:
induces rotation of the gyroscope in the vertical
plane fore and aft (plan XOZ Fig. l), and the 70
other in the vertical plane athwartship (plane
YOZ Fig. 1) assuming the airplane to be for the
moment on even keel.
-
Inthe most common type of bombing opera
tion, after the bombing airplane is on the right '
in which 0 is the complement of the angle made
2,408,356
12
by the axis of torque TX with the spin axis, and,
more to change in a manner peculiar to the type
of bomb and mode of release employed. The fac
tor p is introduced into the overall leverage to
effect such a change,
It will be remembered that in any particular
battle action the altitude h of the airplane and
its air speed S are assumed to remain constant
and therefore the factor 20 does not vary during
any one battle action. It may, therefore, be re
as has been pointed out, ,8 is the angle, measured
in a vertical plane athwartship, by which the
target is oif the vertical plane through the fore
and aft line of the bombing airplane. It is to be
noted that the angle 6 equals the angular dis
’tance the target is ahead of the airplane, meas
ured in the oblique plane that contains the target
and the fore and aft line of the airplane, and the
angle ,8 is the angular distance the target is to 10 garded as a constant factor and‘ treated as a ma
the right (in the problem chosen, Fig. l) of the
chine constant, alter the altitude and air speed
airplane.
have been set at the beginning of the battle ac
tion. The factor p is de?ned as the ratio of the
It is desirable, as has been pointed out above,
that once the sight has been adjusted to point
continuously to the target it be unnecessary to
change the adjustments subsequently as the bat
tle action progresses. It is preferable, therefore,
that the quantities to be adjusted be chosen from
altitude of the plane to the time of ?ight of the
bomb. That is to say,
h
p: T
among those Whose values remain constant
in which T is the time from the instant of release
throughout the battle action.
In the above equations, the factor
20 of the bomb until it reaches the level of the tar
get.
In order to apply these forces, which will be
1
measures in terms related to p, of the velocity
K
components Vx and Vy, I provide suitable force
is always the ‘same for a given gyroscope; the
25 measuring spring 33 and 3! (Fig. 4), together
factor
“with suitable mechanisms for adjusting their
leverages to apply forces which are measures of
1
the velocity components Vx and Vy, respectively,
and apply these forces to the gyroscope gimbal
axes OX and CY at leverages always equal to:
is to be set from time to time, by the bomber, to
agree with the altitude h at which the bombing
plane ?ies during the attack; and the compo
nents VX and Vy of the target’s apparent veloc
ity V0 remain constant. The factors cos3 9 and
cos3 ,8 change continuously as the battle action .
progresses.
The factors cos3 0 and cos3 5 will be generated
and introduced automatically to agree with the
values which the angles 6 and ,6 attain as the
battle action proceeds.
The component torques TX and Ty are applied
I have chosen, therefore, as the quantities to
be measured, the constant velocity components
Vx and Vy, and I adjust the gyroscope and con
to the gimbal axes of the gyroscope l3 to cause
sequently the line of sight in accordance with the
40 the precession of the gyroscope about the fore
measured values of these velocity components.
and aft and athwartship axes through the me
More speci?cally, I apply torques to the gimbal
dium of motors 32 and 33 (Pig. 3). The motor
system of the gyroscope H3 in accordance with
32 applies the torque for precessing the gyro
the above torque (TX, Ty) equations.
scope fore and aft, while the motor 33 applies
It will be observed, with the above torque equa
the torque for processing it athwartship. These
tions in mind, that if constant settings be made
motorsare direct current series motors Without
of some suitable force measuring devices, as for
commutators and apply torques in accordance
example, suitable measuring springs, and if these
with the currents supplied to them. The mo
settings represent and measure forces propor
tors 32 and 33 are always maintained in their
tional to the constant velocity components VX
positions of maximum torque. In other words,
and Vy of the velocity V0, and further if these
the ?elds of these motors are caused to follow
forces be applied to the gyroscope gimbal system
their armatures so that the positions of the ?elds
at leverages always equal to:
relative to their armatures are always those of
maximum torque. This movement of the ?elds
with the armatures is effected by means of suit
55 able follow-up motors 34 and 35 which are suit
in which 10 is a factor, related, to the altitude h
. ably controlled so as to be energized to rotate the
and to the air speed S, that in?uences the ratio
?eld members in vthe proper direction and at a
in which the measured forces are to be propor
speed sufficient to maintain the positions of max
tional to the velocity components Vx and Vy, then
component torques equal to TX and Ty will be ap 60 imum torque between the ?elds and their respec
tive armatures. The follow-up motors 35 and
plied to the gimbal system. In other words, the
35 are provided with suitable direct current elec
gyroscope will be caused to precess at a varying
angular rate so that its spin axis and conse
quently the line of sight will always point at the
target.
trical supply sources 36 and 31 respectively. It
will be understood, of course, that a common sup
ply source may be provided for these motors.
65
Each motor is provided with two oppositely wound
series ?eld windings 49), 49a. and 4!, Ma. Each
set of these windings is controlled by means of
corresponding contact devices 42 and ‘43 whereby
until the description shall have progressed so far
as to make them. more easily intelligible, but I do 70 the starting, stopping and direction of rotation
state here that it is desirable to have the ratio
of the follow-up servo-motors are controlled in
in which the settings of the force measuring de
accordance with the movements of the arma»
vices are proportional to the'velocity components
tures of the respective torque motors 32 and 33.
Vx and Vy change when it changes or when the
The ‘contact devices 42 and 43 are provided with
air speed of the airplane changes and. further
contact arms 42a and 43b mechanically connected
The signi?cance and utility of the factor 10 are
not easy to explain completely at this place and
their complete explanation is therefore deferred
2,408,356
13
14
with the ?eld members of their associated torque
motors 32 and 33 and arranged to cooperate with
spaced contacts 42b and 43a mechanically con
course, will effect a rotation of the servo-motor
in a corresponding direction.
nected to rotate with the armature of these mo
tors so that when the armature of either torque
motors are provided with a suitable direct current
source of electrical supply 58; and the servo
motors 5i? and El are provided with suitable
direct current electrical supply sources 60 and
motor is rotated the associated follow-up motor
will be energized to impart rotation to the motor
The torque application and torque measuring
6! respectively. While separate electrical sup
?eld in the same direction and at a speed sui
ply sources have been indicated for the torque
?cient to maintain the position of maximum
10 motors and for the tWo servo-motors, it will be
torque between the armature and ?eld.
The torque motors 32 and 33 are connected in
series with similar motors 44 and 45 respectively
(Fig. 4), the latter motors serving to measure
the currents supplied to the motors 32 and 33.
The torques of the motors 44 and 45 are bal
anced against the forces generated by the meas—
uring springs 30 and 3 I, and consequently, these
motors serve to measure the components of the
torque applied to the gyroscope.
As shown, the motor 54 is mechanically con
nected with its associated measuring spring 39
by means of a compound lever mechanism 43,
a similar lever mechanism Ill serving to connect
the motor 45 with its associated measuring spring
3 I. It is suf?cient to state at this point that the
overall ratios of these compound lever mecha
nisms are varied by some suitable means, as the
battle action proceeds, so that if the torques of
the motors 44 and 45 just balance the measur
ing springs 30 and 3| respectively, the precession
rates of the gyroscope l3 are just right to keep
the line of sight on the target. In other words,
the overall ratios of these lever mechanisms are
always maintained equal to:
understood, of course, that these motors may be
supplied from a common source.
The control for the torque application motor
32 further comprises a suitable joker switch 62;
a similar control switch 63 is provided for the
torque application motor 33.
These joker
switches are provided so that the maximum elec—
tro-motive force of the supply source 53 may be
applied to the torque application motors 32 and
33 whereby the gyroscope precession rates can be
increased temporarily at will to their maximum
values.
As shown, the joker switches comprise a plu
rality of poles secured to and operated by com
mon control handles 62A and 63A respectively.
Thus, the joker switch 62 is provided with ?ve
poles 62a, 52b, 52c, 62d and 62e. The poles 62a,
62b and 620 have, as shown, two normally closed
contacts; the pole 82d has two normally open con
tacts; and the pole 62c has four normally open
contacts.
It will the observed by reference to
Fig. 4 that when the control handle 62A is moved
in either direction from its neutral position one
contact of each of the poles 62a, 62b, and 620 will’
35 :be opened, while one or the other of the contacts
of the pole 52d will be closed, and also that one
The balances between the torques of the mo
tors t4 and 45 and their respective measuring
springs 30 and 3! are maintained automatically
as the battle action proceeds by suitable servo»
motors 50 and 5!, which serve to control suitable
resistances included in the corresponding circuits
comprising the ?elds and armatures of the torque
application and torque measuring motors 32, 413
and 33, 45. As shown, the servo-motor 50 con
trols a suitable potentiometer 52 included in the
?eld and armature circuits for the motors 32 and
44, while the servo-motor 55 controls a similar
potentiometer 53 included in the ?eld and arma
ture circuits provided for the motors 33 and 45.
Each of the motors 56, 5| is provided with two
oppositely wound series ?eld windings, the mo
tor Eli having series ?eld windings 54, 54a of this
character and the motor 5! having similar ?eld
or both of either the right or left hand contacts
of the pole 624; will be closed depending upon
the extent of the movement imparted to the con
trol handle 62a. The joker switch 63 is provided
with a, similar arrangement of poles 63a, 53b,
63c, 63d and 536.
As has been pointed out, the servo-motors 5i!
and 5| operate to control the currents supplied
to the torque measuring motors 44 and 45, and
consequently to the torque application motors
32 and 33, so that a balance is always maintained
between the torque measuring motors and the
measuring springs 30 and 3| respectively; or in
other words, so that the forces generated by the
springs 30 and (H are applied to the gyroscope
is about its fore and aft and athwartship axes
respectively through the lever mechanisms 46 and
41, the overall ratios of which are always main
55 tained equal to:
windings 55, 55a.
During normal operation the servo-motors 5i]
and 5| are controlled by their respective torque
measuring motors all and 45 by means of suitable
contact devices 56 and 5? respectively, whereby
the starting, stopping and direction of rotation
of the servo-motors are controlled in accordance
with the movements of the torque measuring mo
tors. It will be understood that in operation the
central movable elements of the contact devices
56 and 57 will be moved in accordance with the
movements of the rotors of their associated torque
measuring motors; when either of these elements
has been moved a distance in one direction or
the other suflicient to absorb the clearance be
olizjlrcosa (9.00s3 6
The operation of both torque motor systems is
identical, and consequently only that comprising
the torque motors 32 and M will be described in
detail. Assuming that the various elements of
this system occupy their respective positions
shown in Figs. 3 and 4, it will [be understood that
the series torque motors 32 and 44 will be elec
trically connected in series with the electrical
supply source 53 and the potentiometer 52. This
electrical circuit may be traced from the positive
side of the supply source 58, through the conduc
tor 65, the ?eld 32a of the torque application mo
tor 32, the conductor 65, the ?eld 154a of the torque
measuring motor 4d, the resistance portion 66 of
the potentiometer 52, the contact 5'1 provided for
this potentiometer, the conductor 68, the arma
sitely wound series ?eld windings of the associ
ated servo-motor will be energized, which, of 75 ture 44b of the torque measuring motor M, the
tween it and one or the other of the ?xed con
tacts disposed on opposite sides of it an ener~
gizing circuit for one or the other of the oppo
15'
2,408,356
conductor ‘E5, the normally closedpole 52b of the
joker switch 52, the conductor "H, the armature
32b of ‘the torque application motor 32, the con
ductor ‘l2, the normally closed pole 620 of the
joker switch
the conductor 13, the potentiom
eter contact ‘Ill and thence through the potenti
ometer resistance portion '55 and the conductor
16 to the negative side of the supply source 53.
. As pointed out above, the two torque motor
systems are identical and the electrical connec
16
motor 44 at the pole 62b; ' A power circuit for the.
torque application motor 32, however, is completed
through a suitable controlling resistance, ‘Hi. This
power circuit may be traced from the positive side
of the direct current supply source 58, through the
conductor 64, the ?eld 32a. of the motor 32, the
conductor 65, the conductor 18, the closed right
hand contacts of the pole 62d, the conductor 12.,
the armature 32b of the torque application motor.
32, the conductor 7 i, the portion 80 of the resist‘
ance ‘H’, the conductor iii, the closed extreme
right-hand contacts of the pole 62c and thence
tions between the elements of the two systems
are the same. Thus, the torque application motor
through the conductor 82 to the negative side of
33 (Fig. 3) is electrically connected with the sup
the supply source 58. It will be observed, there
ply source 5.8 and with the torque measuring mo
tor 45 through the switch 53 by means of conduc
fore, that the motors 44 and 59 will have beenex
cluded by the above described operation of the
tors 84c and ‘55a and Na and 12a corresponding
joker'switch, while the torque application motor.
respectively to the conductors E13 and
and ‘H
32 will have been connected in series with the re?
and ‘12 of the system just described.
sistance portion Bil directly to the direct current
It will be understood that when the potentiom
etercontacts 6'?- and ‘ill occupy their neutral po 20 supply source 58. Moreover, it will be observed
that as a result of this operation, the motor 32
sitions shown in Fig. 4 no current will flow
will operate to apply maximum torque to the
through the torque motor armatures; however,
fore and aft gyroscope gimbal axis in a direction
in the event the servo-motor 5% be energized by
corresponding to the direction of operation of the
the'closing of the contact device 55 in either
joker switch 62. It will be understood that the
direction in response to an unbalance in the
resistance portion 88 will be proportioned to give
torques exerted between the spring 353 and its
the maximum torque current to the application
torque measuring motor 44, the resistance ratios
of the potentiometer will be varied by the opera
motor 32. The entire resistance ‘H can be in
cluded in the motor circuit by operating thejoker
tion of the servo-motor 58 so as to cause a cur
rent to now through the torque motor armatures 30 switch control arm 62A so as to close only the
middle right-hand contact of the pole 62a rather
having such a value that the motor 44 will develop
than both right-hand contacts of this pole. This
sui?cient torque to just balance the force gen
provides for the application of a substantially
erated by the spring 39 multiplied through the
lever mechanism 135. When this condition has
constant torque of reduced value to the fore and
aft gimbal aXis of the gyroscope I3.
been attained the contact device 56 will be moved _
to its neutral position, at which position it is
The operations of the joker switch control arm
shown in Fig. 4, so as to deenergize the servo
62A in the opposite direction, that is, in a direc
motor 50. It will be readily appreciated in View
tion to move the pole arms to the left, as viewed
of the foregoing discussion that the torque appli
in Fig. 4, provides for similar controlling effects
cation motor 32 will apply the same torque to its 40 on the operation of the torque application motor
fore and aft gimbal axis as is exerted by the
32 but in the opposite direction.
torque measuring motor 44 on the spring 39
The operation of the joker switch 63 and its
through the lever mechanism 426. It is to be un
resulting control of the torque motors 33 and 45
derstood that the servo~motor 5% will operate
is exactly the same as described in connection
to control the potentiometer 52 so as to always '
with the control of the torque motors 32 and 44
cause a current of the proper value to flow in
effected by the opera-tion of their control switch
the armature circuit of the torque motor 44
62. Thus, with the switch arm 63A in its neutral
whereby the torque exerted by this motor will
position, as shown in Fig. 4, the servo-motor 5!
balance the force generated by the spring 39
will be permitted to operate to maintain a bal
multiplied through the lever mechanism 416 with
ance between the torque measuring motor 45
the result that the torque application motor 32
will always apply to its fore and aft gimbal axis
a torque equal to the force generated by the
spring 355 and multiplied by the lever mechanism
and the measuring spring 3|, whereby the
applied to the athwartship gimbal axis
gyroscope by the torque application motor
be measured and controlled. The joker
46.
control arm 63A may be moved to its limiting
position in either direction so as to e?ect a de
If it be desired to cause the torque application
motor 32 to apply maximum torque to the fore
and aft gimbal axis of the gyroscope l3, i. e., if
it be desired to cause the gyroscope to precess at
its maximum rate, it is merely necessary to throw
the joker switch control arm 62A in one direc
tion or the other depending upon the direction at
which it is desired to precess the gyroscope. For
the purpose of illustration, assume that the joker
switch control arm 62A is moved so that the pole
arms 62a, 62b, 62c are moved to the right as
viewed in Fig. 4. It will be observed that this op
eration causes the left hand contacts of the poles
62a, 62b, and 620 to open, the right hand contacts
of the pole 62d to close and the two right hand
contacts of the pole 62a to close. t will be ob
served that this operation effects an interruption
of the power circuit for the servo-motor 50 at
the pole 52a, and likewise effects an interruption
of the power circuit for the torque measuring
torque
of the
33 will
switch
energization of the servo-motor 5i and the torque
measuring motor 45, while establishing power con
nections for the torque application motor 33
through a portion of the resistance 83 thereby
providing'for the application of maximum torque
to the athwartship gimlbal axis in a direction cor
responding to the direction of movement of the
contact switch arm; or the switch arm 63A may
be moved from its neutral to its intermediate posi
tion in either direction so as to e?ect the applica
tion of a reduced torque of substantially constant
value to the athwartship gimbal axis.
'
It will be observed in view of the foregoing dis
cussion that the joker switches 62 and 53 pro
vide a means for applying a substantially con
stant torque havnig either maximum or a reduced
value to the respective gimbal axes of the gyro
scope IS without affecting the settings of the
springs 30 and 3|.
‘
2,408,356
17
I36 and 41 by means of levers H4 and H5 each of
which is pivotally mounted on its associated sup
port. It will be observed that each of these levers
has a right angle form, one leg being positioned
vertically and the other horizontally, as viewed in
It will be remembered that the settings of the
springs 39 and 3| will be adjusted so as to gen
erate forces which will be measures in terms re
lated to p, of the target’s apparent fore and aft
and athwartship velocity components Vx and Vy
respectively. It will also be remembered that
Fig. 4..
these forces are to be applied to the gyroscope
gimbal axes OX and OY at leverages always equal
to:
10
Li.
p.K
h cos 3 6.00s 3 ,8
The vertical legs as shown are pivotally
connected intermediate their ends to up-right
rigid supporting portions Him and HM formed
on the supports I I2 and I I3, while the horizontal
legs are provided with anti-friction bearings on
their associated levers I08 and I09. The springs
30 and 3!, which preferably although not neces
sarily will be of the compression type, are inter
the factors cos3 0 and cos3 5 being introduced
posed between the vertical portions of their le
automatically and continuously to agree with the
values which the angles 0 and e attain as the 15 vers H4 and H5, and the parallel upright rigid
portions of the members IIZa, II3a formed on
battle action proceeds.
their respective supports I I 2' and I I3, as is clearly
The factor
shown in Fig. 4. It will be readily understood
that by reason of the above described lever and
NIH
is always the same for a given gyroscope. The
factors 22,
l
h
cos3 0 and cos3 ,B, as has been pointed out, are in
20 spring arrangements the forces applied by the
springs on their associated levers H4 and H5
will be transmitted by the lever mechanisms 46
and 41 to their respective torque measuring mo
tors 44 and 45.
The leverages of the springs 30 and 3| on their
25
associated lever mechanisms 46 and 41 are con
troduced by the compound lever mechanisms 46
and 4-1. The factor
trolled by means of suitable adjusting screws I I6
and H1 respectively which as shown are in
threaded engagement with the adjustable sup
2
h
or, which is the same thing
30
ports H2 and I I3 provided for the springs. It
will be obvious that the effective forces exerted
by the springs 30 and 3I on their lever mecha
nisms 46 and 41 can be controlled readily by
i
means of these screws. In other words, the set
T
is introduced to these mechanisms by the levers 35 tings of the adjusting screws H6 and II‘! repre
sent and measure in terms related to p, the con
98 and BI respectively, the factor cos3 .n is intro
stant
apparent velocity components Vx and Vy in
duced by the levers 92 and 93 respectively; and
the
above
torque equations.
the factor cos3 0 by the levers 94 and 95.
The adjustable fulcrums 96 and 91 of the levers
It'will be observed that the levers 90 and SI
90 and SI are controlled by means of a suitable
are provided with adjustable fulcrums 95 and 91;
and that the levers 92 and 93, and 94 and 95 are
provided with adjustable fulcrums 98 and 99, and
I90 and It! respectively. These fulcrums are
double acting; in other words, the fulcrums are
arranged so that they can exert either a pushing
or a pulling action on their associated levers.
For this purpose the levers as shown are pro
vided with suitable channels arranged longitudi
nally thereof and in which are received suitable
adjusting screw II8 which is mechanically con
nected with both of the fulcrums so as to e?ect
a simultaneous adjustment of these members.
As shown, the adjusting screw H8 is in threaded
engagement with the fulcrum 96 so as to impart
motion directly thereto, and is connected to the
fulcrum 91 by means of a shaft I20, to one end
of which the ‘screw is connected by means of
suitable bevel gears I2 I, and by means of a screw
studs or pins provided on the associated ful 50 I22 connected to the other end of the shaft I20
by bevel gears I23, and to the fulcrum 91 by a
crums. This double acting arrangement is
suitable threaded connection. This arrange
necessary because during the battle action the
ment insures a simultaneous adjustment of the
fulcrums at times may apply forces on their asso
fulcrums 96 and 91 in the same direction and to
ciated levers in one direction, while at other times
the same degree. Therefore, the setting of the
55
they may apply forces in the opposite direction.
screw II8 represents and measures the factor
It will also be observed that the levers 9E! and
ill are mechanically connected at their upper
P
ends, as viewed in Fig. 4, through suitable anti
friction joints I 52 and I93 with the armatures
of the above torque equations or its equivalents,
Mo and 45b of the torque measuring motors 44 60
viz.
‘
'
and 45 respectively, and at their lower ends are
1
connected by means of similar joints I04 and I05
with the upper ends of the levers 92 and 93 re
spectively. The lower ends of the levers 92 and
The control of the cos3 p and cos3 0 levers 92
93 are similarly connected with the upper ends 65 and 93, and 94 and 95 respectively is effected by
of the levers 94 and 95 by means of joints Hi6 and
moving their adjustable fulcrums. As has been
I91, the lower ends of the latter levers being op
pointed out, the over-all ratios of the compound
erably associated with the measuring springs 3i)
levers 46 and 41 will be varied automatically as
and 3! through the medium of suitable levers I 08
the battle action proceeds so that if the torque
of motors M and 45, and consequently, the
and I139, to which they are connected by means
torques of the precession motors 32 and 33, just
of suitable anti-friction joints III! and I I i.
balance the forces applied by the measuring
As shown, the measuring springs 30 and 3I are
springs 39 and 31, the precession rates of the
mounted upon suitable vertically adjustable
gyroscope I3 will be just right to keep the line of
supports I I2 and I I 3, and are connected to apply
their forces to their respective lever mechanisms 75 sight on the target.
2,468,356
.
19
The automatic apparatus for controlling the
cos3 B and cos3 6 levers is arranged so that the
line of sight is kept moving over the ground or
water to follow the target in a straight line in
whatever direction and at whatever constant
speed the bomber has set on the adjusting screws
H5‘ and Ill. The manual adjustment by the
bomber consists in setting the screws I I6 and I I1
until the components of the motion of the line
20
its spin axis will describe the same cone about
the earth’s axis that the true vertical describes,
and at the same rate.
Preferably, a suitable member I28 provided with
a latitude scale I29 will be provided so as to as
sist the bomber in the adjustment of the weights
to latitude. This scale may be provided with a
zero position, which position is designated in Fig.
3 by the letter “N,” and may be graduated in de
of sight over the ground or water are just right 10 grees latitude in each direction from the zero
to keep the sight on the target; the bomber uses
point. These graduations in degrees latitude in
the screw II6 to vary the speed fore and aft, and
each direction from the position “N,” in effect,
the screw II‘! to vary the speed athwartship.
form two separate scales, one for each latitude
It is desirable in order to make the proper ad
weight so that in adjusting the weights to latitude
justments of the movable fulcrums provided for 15 it is merely necessary to set each weight opposite
the 0053 0 and cos3 ,3 levers to measure the angles
the corresponding latitude indication on its as
or and ,8, to convert these measurements into suit
sociated scale.
able angular functions, and apply them to the
The latitude scale member I28 which as shown
fulcrums in the terms of these functions.
preferably will be of disc form is carried by a
This necessitates a vertical seeker or a vertical 20 suitable sleeve member (not shown) arranged for
keeper, i. e., some standard of judgment of the
rotary motion on a suitable vertically disposed
vertical. For this purpose, I have provided a neu
trally suspended gyroscope I24 (Fig. 3); it is to
bearing member carried by the gyroscope casing
I27 (which bearing member is not shown but
be understood, however, that any suitable ver
which may be one of the afore-mentioned ver
tical seeker or keeper may be used.
25 ' tical extensions, preferably the upper one, pro
As is well understood by those skilled in the
vided on the gyroscope casing to support the
art, a neutrally suspended gyroscope does not
weight rings I26), so that the zero position “N"
maintain a vertical even though adjusted to the
of the scale may be directed at will toward the
vertical initially, but tends to maintain a con
north.
stant direction in universal space. As is also well so
Preferably the latitude weight rings I26 will be
understood, the nadir is moving at the rate of
provided with suitable means for locking them
to the disc I28 so that the disc together with
the neutrally suspended gyroscope I24 to main
the ring members located in their adjusted posi
tain a vertical, I apply to the gyroscope a cor
tions with respect to the latitude scale I29 can
rective precessing torque in accordance with the 35 be moved as a unitary structure. For this pur
change in true direction of the nadir (caused by
pose,,each ring is provided with a suitable re
the earth’s rotation) so as to maintain the spin
silient latching member I 3!! arranged as shown
axis of the gyroscope vertical. This corrective
to engage suitable serrations provided in the edge
precessing torque is applied to the gyroscope by
of the disc I28.
means of a pair of latitude weights arranged to 40
In order'to assist the bomber in directing the
cause the gyroscope to precess from west to east
mid point between the weights I25 toward the
at the rate of 15° per hour-cos of latitude. I have
north, the disc member I28 is provided with a
provided a pair of latitude Weights I25 for this
second scale I32 arranged to cooperate with an
purpose. It will be understood that these weights
index I33 ?xed in any suitable manner to the
will be located on and adjustable along the equator 45 gyroscope casing. This scale may be graduated
of the gyroscope; as shown, the weights I25 are
in degrees from zero to 360, or may be graduated
mounted on suitable ring members I26 arranged
in any suitable manner so that the bomber with
to rotate on vertical extensions (not shown) of
the knowledge of the airplane’s position relative
the gyroscope casing I 21.
to the target at the outset, i. e., the bearing of
It will be understood that the latitude weights
the target from the point of departure, can cor
425 are arranged on their ring supporting mem
rectly adjust the weights so that the mid point
bers I25 so as to be located on the equator of the
between them is directed toward the north.
gyroscope and that they may be adjusted along
, I prefer to provide suitable means for locking
this equator merely by moving the ring members
the latitude scale together with the latitude
relatively to each other.
55 weights secured thereto in their proper adjusted
It will also be understood that the latitude
positions, once the scale has properly been set so
weights are so proportioned to the properties of
that the mid point between the weights is di
the gyroscope that if they are set close together
rected toward the north, to the gyroscope casing.
on the north: side of the gyroscope and are kept
For this purpose I provide a suitable resilient
pointing to the north they will 'cause the gyro
60 latching member I34 mounted on the gyroscope
scope to precess from west to east at the rate of
‘casing and arranged to engage suitable serra
15° per hour assuming the gyroscope to be placed,
tions provided on the edge of a disc locking
with its spin axis vertical, at the earth’s equator.
member I 3%, formed integrally with or other
15° per hour >< cos of latitude. In order to cause
If the weights are separated by moving them
along the equator‘of the gyroscope, but the mid
point between them be kept toward the north,
they will partially balance each other and will
exert less torque on the gyroscope but will still
wise suitably mechanically connected to rotate
with the latitude scale member I28. This disc
member I34a. may be secured to the above-men
tioned bearing member (not shown) provided for
the disc I28.
cause it to precess from west to east at a lower
It is also to be understood that the gyroscope
rate. Therefore, if the latitude weights I 25 be 70 will be adjusted to the vertical by some suitable
adjusted a suitable distance apart, this distance
means, such as suitably arranged crossed spirit
being in accordance with the latitude of the 10
levels (not shown), as shortly as possible before
cality in which the gyroscope is located, and if
the approach of the bombing airplane is begun,
the mid point between the weights be kept to
This adjustment may be made on the ground be
ward the north the gyroscope will precess so that 75 fore taking off or in the air during a time when
2,408,856
'21
22
the pilot is ?ying, as nearly as he can, a straight
electromotivev forces are induced'in theqcircuits
of the armature windingsv I35a and 131a v'of- the
transmitting and receiving instruments I35‘ and
horizontal course.
,
If desired, the latitude weights may be ren
dered ineffective by setting them to 90° latitude.
While any suitable means may be used to
I3‘! by their associated ?eld windings I35b and
I3‘Ib since these ?eld windings are supplied with
alternating current. The armature and. ?eld
members of the receiving instrument I31 tend to
take up a position relative to each other ‘such
measure the angles on and I8 and to transmit the
measured values of these angles to some point
in the mechanism where they may be utilized, I
prefer to use a~motion transmission system com
that the electromotive forces induced in the ar
prising transmitting and receiving instruments 10 mature winding by the ?eld winding are opposite
to and match the electromotive forces induced
of the self-synchronous type. In accordance
in the armature of the transmitting instrument
with a system of this type the angles sand ,8 will
by its ?eld winding. When the armature: andv
be measured by suitable self-synchronous gener
?eld windings of the transmitting instrument
ators I35 and I36 (Fig. 3), and these measure
ments will be transmitted to corresponding self 15 are moved relatively to each other the electro
motive forces induced in the transmitting arma
synchronous receiving instruments I31 and I38
ture winding are changedrelatively in magni
(Fig. 4). It will be understoodthat the trans
tude, with the result that an exchange of cur
mitting and receiving instruments of each set are
rent takes place between the transmitting‘ and
similar in construction; the construction of only
one set, via, the set comprising the instruments 20 receiving instruments due to the unbalanced
voltage condition between the two instruments,
I35 and I31, therefore, is shown in detail (Fig. 9).
whereby the armature and ?eld windings of the
The transmitting and receiving instruments I35
receiving instrument tend to take up a new 'rel- ‘
and I31 are somewhat similar in construction,
ative position in which position the electrome
each being provided with a poly-circuit armature
winding and with a ?eld winding, one of these 25 tive forces are again opposite and matched. Due
to the fact that the transmitting instrument ‘has
windings being mounted on a rotor member. As
twenty-four poles, it will be observed that‘ the
shown, the armature winding I35a in the trans
electromotive forces induced in its armature
mitting instrument is mounted on the rotor
winding will pass through a complete electromo
member while the ?eld winding I3'Ib in the re
ceiving instrument is mounted on the rotor mem 30 tive force cycle every 1130f a revolution of rela
tive movement between the armature and ?eld
ber. The armature windings HM and I3'Ia, pro
windings, that is, starting with zero the electro
vided for the transmitting and receiving instru
motive force in any particular coil of the arma
ments are physically similar to three-phase dis
ture winding will increase in one direction to a
tributed armature windings. As shown, like
points of the armature windings I35a and I31a 35 maximum value, decrease to zero, and then in
are interconnected electrically, while their ?eld
windings I35b and I3'Ib are connected with a
crease in the opposite direction to a maximum
value and decrease to zero again each 1% of a
suitable alternating current ‘source of electrical
revolution of relative movement between the ar
mature and ?eld windings, This cycle tends to
40 produce a complete revolution of relative move
supply I39.
'
As shown (Fig. 3), the armatures of the'gener
ators I35 and ‘I36 are connected mechanically
with the athwartship and the fore and aft gim
bal axes of the gyroscope I24 respectively, While
their ?eld members are connected mechanically
with the corresponding gimbal axes of the gyro
ment between the armature and ?eld windings of
the bi-polar receiving instrument.
The result
is that for each revolution of relative movement
between the armature and ?eld membersof'ithe
transmitting instrument the receiving vinstr'ue
scope I3. The armature I 35a ‘of the generator
I35 is connected with the athwartship axis of the
ment will tend to rotate through twelve complete
gyroscope I24 by means of a suitable crank and
The receiving instruments I31, and I38, how
link arrangement I350, while the rotor I36a of
the generator I36 is connected directly with the
ever, instead of measuring the angles a and 5
directly, are connected to control suitable servo
motors I40’ and ~I4I respectively which will be
utilized to measure convenient functions of these
angles. As shown, the motors MI] and IM are
fore and aft axis of the gyroscope I24.
revolutions.
Conse
quently, the armatures of these generators will
be maintained in ?xed angular positions in
space, while their ?eld members will be driven
by the gyroscope I3 through its precession angles .
a and (3.
‘
In order that the angles a and B can be trans
mitted and determined with great accuracy, I in
troduce a speed ratio between the transmitting
instruments I35 and I36 and their respective
receiving instruments I37 and I38. For the pur
pose of introducing this speed ratio the transmit
ting instruments are provided with a greater
number of poles than are their receiving instru:
ments. As shown (Fig. 9), the ?eld member I351)
of the transmitting instrument I35 is provided
_
~
'
t
.
supplied electrically from the direct current supply
I
source 60, and'are provided with two oppositely
Wound series ?eld windings I42, I 42a and "I63,
I 430, respectively. Each set of these windings
is controlled by means of corresponding contact
devices I 44 and I45 whereby the starting, stop
ping and direction of rotation of the servo-mo
tors are controlled in accordance with the opera
tion of the self-synchronous motors ; I31 and I38.
The servo-motors I43 and MI are provided with
threaded shafts I 45 and I 41 respectively on which
are threaded travelling nuts I58 and I5I. These
nuts are connected by means of suitable lever or
crank arms I52 and I53 with the respective are
mature members of the receiving motors I31‘ and
I38. The ‘levers I52 and I53 are'mounted‘ on
with twenty-four poles thereby rendering the
transmitting instrument a twenty-four pole in
strument, whereas the receiving instrument I3‘I
is provided with but two poles. Similarly the 70 ?xed pivots I 52a and I53a respectively and are
mechanically connected with their respective ar
transmitting instrument I35 is provided with
mature members I3‘Ia and I38a'by'means of gear
twenty-four poles while its receiving instrument
connections comprising spur gears I521) and IE3!)
is provided with but two. It will be understood
that in each self-synchronous motion transmis
sion set, as for example that shown in Fig. 9,
arranged to rotate with the armature members
and segmental gear members I5Zc'and il>53c~°=ari
2,408,356
23
24
ranged on they levers I52 and‘ I53 to mesh with
[58a arranged to keep’ the rods bearing on their
the spur gears.
respective cams I55 and I56.
The cams I55 and I56 are suitably shaped and
are controlled by the tan on and tan 5 movements
of the shafts I46 and I41 so as to give a ratio to
the levers 94 and 95 which is proportional to
005.3 6. For this purpose, I have provided a suit
able motion transmitting mechanism which com~
prises a slider I6I in screw threaded engagement
These gear connections are so
arranged that the armature members I316. and
I38a are turned through twelve times the angle
of movement imparted to their respective levers
I52 and I53. In other words, the levers {52 and
I53 will be rotated by their motors I46 and I4I
through angles equal in magnitude to the angles
transmitted by the transmitting instruments I35
and I36 respectively. This arrangement is nec
essary because of the 12-1 ratio introduced be
tween the transmitting and receiving instruments
1.0 with the tan a shaft I46 and movable in suitable
guides I62. This slider is connected with a simi
lar slider I63 by means of a link I64 having an
adjustable pivot I65. The latter slider is ?xed
of the motion transmission sets. It will be ob
to a rack I66 which meshes with a gear I61 ar
served that each lever I52, I53 has a sliding con
nection with its travelling nut which connection 15 ranged to turn the cam I55, and also the cam I56
through the shaft I60. The adjustable pivot I65
serves to prevent rotation of the nut on its shaft
for the link I64.is mounted in a slider I68 move
and thereby constrain the nut to move longitudi
able in a guide I69 in a direction at right angles
nally on the shaft when the latter is rotated.
to the movements of the ?rst mentioned sliders.
It will be understood that each contact device
I44, I45 is mechanically connected with the ?eld. 20 The ratio of the lever I64 is kept proportional to
cos B by means of a cam I"!!! which is connected
member of its associated receiving motor I31,
to be operated by the tan 3 screw I41. As shown,
I38 so that when this member is moved in one
direction or the other in response to the operation
this cam is turned by means of a gear and worm
of the corresponding transmitting generator I35,
drive HI, and motion is transmitted from this
I36, a control circuit will be completed for the
controlled servo-motor I46, MI. The servo-mo
tor I46, MI in response to the completion of this
circuit will cause the associated nut I59,‘I5I to
cam to the adjustable pivot I65 by means of a cam
follower or rod I12. This rod is kept bearing on
its cam I19 by means of a suitable spring member
I12a or equivalent device.
It will be observed, in view of the foregoing
move longitudinally of its screw so as to impart
arrangement, that the rack I66 has a movement
rotary motion to its connected receiving motor
that is always proportional to tan ozXCOS c, which
armature. Moreover, it will be understood that
as will be observed in Fig. 1 is equal to tan 0.
the servo-motor I 40, MI will continue to rotate
The cams I55 and I56 by virtue of their shape
, until the armature of the associated receiving mo
and the tan 0 movement which is applied to them
tor I31, I38 has been moved to such an angular
move the fulcrums I69 and MI to give a ratio
position with respect to its ?eld that the matched
to their associated levers 94 and 95 which is pro-1
voltage condition in the armatures of the receiv
portional to cos3 0.
ing motor and its transmitting generator I35, I36
has been restored. When this condition has been
‘The cos3 ,6 functions are applied to the lever
mechanisms 46 and 41 directly from'the tan ,6
established, the contact device I44, I45 will be
returned to its neutral position so as to deenergize 40 shaft I41. These functions are applied vto the
the associated servo-motor. In each case, there
fulcrums 98 and 99 provided for the cos3 {3 levers
fore, when the armature of the receiving instru
92 and 93 by means of suitable cams I13 and I14
respectively. As shown, these cams are mechani
menthas been moved by its servo-motor through
an-angle equal to twelve times the angular move
cally connected with their respective fulcrums by
ment of its transmitting instrument, the servo 45 means of cam rods I15 and I16, and are con
motor‘ will be deenergized.
nected with each other by means of a shaft I11
so that it is only necessary to impart motion to
It will be observed that in either case when
the armature of the receiving instrument I 31, I33
one or the other of the cams, or to the shaft, in
order to adjust both fulcrums 98 and 99. I im
has been rotated by its associated nut I59, I5I
part motion from the tan p shaft I41 directly to
through an angle equal to twelve times the angle
the cam I13 by means of a worm gear drive I18.
a, B through which the transmitter I35, I36 has
been moved, the distance which the nut will have
It will be understood that the cams I13 and I14
travelled on its shaft will be a measure of the
will be suitably shaped so that they will translate
tangent function of the angle 0:, p. In other words,
the tan 5 movement of the shaft I41 to move the
fulcrums 93 and 99 to give ratios to their respec
tive levers 92 and 93 proportional to cos3 5. Suit
able spring members I'I5a and H611 are provided
in the screw shaft I41.
'
to keep the cam rods I15 and I16 bearing on
The tan a and B movements of the shaft I46
their respective cams I13 and I14.
and I41 respectively are applied to the lever
It will be observed in view of the foregoing
mechanisms 46 and 41 so as to introduce‘the 60
discussion that the adjustments of the lever
functions cos3 0 and cos3 5.
mechanism 46 and '41 interposed between the
In order to introduce the function cos3 0, I
measuring springs 30 and 3 I and the torque meas
have provided suitable cams I55'and I56 which
uring motors 44 and 45 is partly at the will of
serve to impart motion directly to the fulcrums
the bomber and is partly automatic. And more
I66 and IBI providedfor the respective cos301evers
over, that the automatic adjustments of these
94 and 95. As shown, these cams are mechane
lever mechanisms in response to the precession
ically connected to their associated fulcrums by
of the gyroscope I3 are such that the fore and
means of cam rods I51 and I58, and are mechan
aft and athwartship precession rates of the gyroically tied to each other by means of a shaft I63 70 scope are varied so that given settings of the
so that it is merely necessary to impart motion
measuring springs 36 and 3i shall correspond to
to one or the other of the cams, or to the shaft,
a constant apparent linear speed of the target.
in order to control both fulcrums I96 and- “II.
Attention is again called to the fact that it is
the apparent linear speed along the ground or
As shown, the cam rods I5‘! and I53 are~pro7
vided' with suitable spring members I51a and .
water thatis constant for constant‘ conditions. ‘
the angle on is converted to tan ‘a in the screw
shaft I46, while the angle e is converted to tan b
2,408,356
25
26
of the air speed andthe altitude. The value of
the air speed S, which will have been determined
It is desirable that the proper sight offsets be
deduced and applied so as to cause the bomb to
be released at the proper time. It is also desir
able that the bomber incidentally determine the
proper sight oifsets as he sets the measuring
in any suitable manner, is set by the adjusting
screw I80 on its associated scale l8l. The effect
of this setting is to adjust the position of the
aperture I82, through which the altitude it may
springs 30 and 3| to correspond to the constant
apparent linear velocity components of the
be read on the associated scale I83, so as to per
mit the setting of the time of flight in terms of
the altitude and air speed. It is assumed, of
target.
It will be observed that if in the chains of
levers 46 and 41, which introduce the factors p, 10 course, that the altitude h will have been de
termined previously by any suitable means.
1
Consequently the time of ?ight factor
1
cos3 0 and cos3 5 among the factors by which the
measured forces of the springs 30 and 3i are to 15
be multiplied to give the correct precession
may be introduced in the mechanism merely by
torques to the gyroscope l3, the factor
adjusting the screws H8 and lat in accordance
1
with the known values of air speed S and alti
tude h.
The effect of the adjustments of the time of
in which T is the time of ?ight of the bomb for 20
?ight screw I I8 is to change the ratio of the lever
altitude h) be included, then the settings of the
arms A and B (Fig. 4) of the levers 96 and 9| in
measuring springs will remain constant for con
accordance with the following equation:
stant velocity components Vx and Vy of the tar
get’s motion but will in fact measure TVX and
TVy, the components of the target’s total motion 25
during the interval from tr, the time of release
to t1, the time of impact.
wherein A is the effective length of the lever arms
It will also be observed that TVx is the range
between the fulcrums 96 and 9'! and the points
forward plus the trail and TVy is the range 30 of connection between the levers 9!] and 92 and
athwartship.
9| and 93 respectively, and B is the eifec'tive length
Referring to Fig. 1 it will be understood that
of the lever arms between the fulcrurns 96 and 91
and the points of connection between the levers
Titfz=tan ar+tan trail angle, and
9B and the torque motor 44 and between the lever
35 9| and the torque motor 45 respectively.
TV,,_
In view of the fact that the lever mechanisms
h --tan 6,.
46 and 41 are identical with respect to their con
struction, and in viewvof the fact that the ful
wherein, as has been pointed out, on: is the range
angle forward, or the value 0: must have at the
crums 96 and 91 of the two mechanisms always
instant of release, and 18s is the range angle 40 occupy the same positions relative to their asso
ciated levers 90 and 9|, the following discussion
athwartship or the value 5 must have at the in
of the mechanism for introducing the time of
stant of release.
?ight factor
It is to be remembered that p has been so
1
de?ned that
45
ale
into the lever mechanisms will include only the
lever mechanism 46 it being understood that ad
justments of the time of ?ight screw H8 effects
50 like controlling actions in both mechanisms 46
therefore, in these chains of levers 46 and 4'!
the group of factors becomes:
%- cos3 (9.00s3 43
and 41.
_
It will be obvious that when the fulcrum 96 is
in its mid position, or in other words, when the
which is equal to
and the settings of the measuring springs 30
lengths of the arms A and B are equal to each
55 other, the adjusting screw H8 will have been
set so as to introduce into the lever mechanism
46 unit time of ?ight. The unit of time chosen
may have any suitable value, the value chosen
trail angle and tan ?r, respectively. This is the
depending to some extent upon the length of the
complete explanation of the signi?cance and util 60 lever 90 and to some extent upon the maximum
ity of the factor p‘ introduced earlier in the speci
number of seconds time of ?ight that it is contem
31 measure directly the quantities vtan ur+tan
?cation.
.
The factor
1
plated will have to be provided for, the important
feature being that a relatively large portion of
the length of the lever be utilized in e?ecting
65 adjustments for time of ‘flight between zero
seconds and the maximum number of seconds to
be provided for. Thus for example, if it be
assumed that the greatest time of ?ight T to be
adjustment of the screw H8 for the time of
provided for be forty seconds and that the lever
?ight factor
70 have a length of four inches, a convenient unit of
1
time is twenty seconds.
It will be understood that the fulcrum 96 for
any particular time of ?ight T that must be pro
may be determined mechanically in terms of the
vided for within the limits from zero to the maxi~
altitude h and the air speed S, it being under
stood that the time of ?ight is a joint function 75 mum number of seconds will have to be adjusted
is introduced directly into the mechanisms by
means of the adjusting screw H8.
The proper
2,408,356
27
28
so that the ratio of the lengths of the lever arms
A and B will be equal to
wherein T is the particular time of ?ight, may be
calculated.
'
'
"
As has been pointed out, it is the function of
the scales l8! and I83 to assist the bomber in‘
adjusting the fulcrum 96 to the proper position
1.
T
in accordance with the above equation:
to introduce the factor
Li
'
' -
1
B“ T
wherein T is the particular time of ?ight in terms
of the chosen unit. Let it be assumed for the
purpose of explanation that the length of the
lever 96 be four inches and that the maximum
time of ?ight to be provided for be forty seconds.
Having chosen a unit time of ?ight, such for ex
ample twenty seconds, it will be understood that it
is necessary to determine just What position the
fulcrum 95 will have to occupy for each particu»
lar time of ?ight T so that the ratio of lengths
of the lever arms A and B in any case will be
equal to
10. into the lever mechanisms in terms of the known
data: the altitude h and the air speeds of the
airplane. As has also been pointed out, the scale
I8I is graduated to indicate air speeds and the
scale I 83 is calibrated to indicate altitude hin
terms of the time of ?ight T for various air speeds
' so that the setting of the screw H39 to air-speed
automatically selects the proper altitude scale on
the scale I83, whereby if the screw I 18 be turned
to indicate on this scale the actual altitude h
of the attacking airplane, the fulcrum 99 will be
moved to such a position that the ratio of the
lever arms A and B will be equal to
'sIH
'
1
or in other words,
The altitude scales for the scale I83 may be
unity
T
wherein in the example given, unity equals twenty‘
seconds. Suppose it be desired to determine the
position of the fulcrum 96 to give proper lengths
to the arms A and B for the maximum chosen
time of forty seconds; then in accordance with
the equation
In other words, for forty seconds time of ?ight
T, the length of the arm Azlength of the arm
B::1:2; it will be obvious, therefore, that in a,
conveniently determined as follows: Let' it be as
sumed for the purpose of explanation that one
revolution of the drum on which the scale I83 is
mounted provides for the total range of move
ment of the fulcrum 96. If it be assumed, as be
fore, that the lever 90 has a length of four inches
and that the maximum number of seconds time
of ?ight'to be provided for is equal to forty sec
onds, then it will be observed that one revolu
tion of the drum or scale I83 corresponds to a
movement of 2.666 inches of the fulcrum down
wardly from the joint I02, which range of move
ment, as has been pointed out, will provide for
lever having a length of four inches the arm A 40 any time of ?ight between zero seconds and the
chosen maximum of forty seconds. With the
for forty seconds time of ?ight T will be equal
above information, the portion of a revolution of
to 1.333 inches, whereas the length of the arm
the scale I83 corresponding to the position of the
B will be equal to 2.666 inches, and that the ful~
fulcrum 96 for any particular time of ‘flight T
crum 95 must be moved to a position 2.666 inches
below the joint I02 connecting the lever 96 to ~15 so that the ratio of the lengths of the arms A
and B is equal to
r
the torque motor 44 in order to introduce the
factor
>
1
1
into the lever mechanism 46.
Again, suppose that the time of ?ight T be equal
to ten seconds; then in accordance with the equa
tion
may readily be determined. For example, suppose
that it be desired to determine the portion of a
revolution of the scale I83 corresponding to the
position of the fulcrum 96 for ten seconds time
of ?ight, which position, as has been determined
above, is 1.333 inches below the joint H12. If X
55 be assumed to be the portion of a revolution cor
B
T ’ B_ 10“ 1
responding to this position of the fulcrum, then
In other words, for ten seconds time of ?ight T,
x
the length of the arm A:length of the arm B: :2: 1.
1 revolution
In a lever four inches long A will be equal to
1.333” (corresponding to 10 seconds)
2.666 inches while B will be equal to 1.333 inches. 60
2.666’ '(corresponding to 40 seconds)
In order to introduce the factor
The scale, therefore, must be turned through one
1
half of a complete revolution in order to bring
the fulcrum 96 to the proper position to intro
in the lever mechanism, therefore, the fulcrum 65 duce into the lever mechanism the factor
96 will be moved so as to occupy a position 1.333
1
inches below the joint I62.
Similarly for each particular time of ?ight T
wherein T is equal to ten seconds. ,
between zero and the maximum time of ?ight
In like manner the portions of a complete rev
to be provided for the position which the fulcrum 70
olution of the scale I83 corresponding to the po
96 must occupy so as to introduce into the lever
sitions of the fulcrum 96 for other particular times
mechanism the factor
V
of ?ight T may readily be determined.
-
In certain instances it may be more convenient
.75 to determine the number of inches of movement
2,408,356
29 '
30
lécted; whereby it' is, merely necessary for the
on the circumference of the scale corresponding
tov the positions occupied by the fulcrum 96 for
the various times of ?ight T. Then, if the circum
ference of the scale be 10", it will be obvious that
the drum must be moved through 5" of circum
bomber to adjust the screw I I8 to bring the index
of the scale I83 to the altitude at which the air
plane is actually ?ying to introduce into the
ference to bring the fulcrum 96 to a position 1.333
inches from the joint I02 so as to introduce into
_1
the lever mechanism the factor
'
'
l
'
T
mechanism the proper factor
'
corresponding to_ the air speed and altitude of the
10
.
wherein T is equal to ten seconds; again, the drum
must be moved through ten inches of circumfer
ence to bring the fulcrum to a position 2.666" be
airplane.
‘
' Itis also to be ‘understood that the threaded
connection between the adjusting screw I I8_ and
the fulcrum 96 will be so arranged and propor
tioned'to the geared connection between this
and the drum I83 that when the drum is
low the joint I92 which position corresponds to 15 screw
adjusted to indicate a given altitudefor a par
the ‘chosen maximum time of ?ight T of forty
ticular air speed, the fulcrum 96 will be moved ,
seconds. It will be obvious that the number of
along the lever 90 to its proper position so as to
inchesof circumference on the drum correspond
introduce into'the lever mechanism the factor
ing to other positions of the fulcrum for various
1
times of ?ight T may be readily determined.
The altitude scales may readily be determined
by plotting a curve with seconds time of ?ight
and the corresponding inches circumference on
the scale as coordinates. Referring to Fig. 10
such a curve is shown plotted with “Seconds time
of ?ight” as ordinate and “Inches circumference
wherein T corresponds to the altitude indicated
'on the scale, '
It will also be understood that if different types
‘- of bomb be used altitude scales calibrated in ac
particular air speed S'may readily be determined
cordance with the characteristics of the different
types will be provided.
It is again pointed out that any adjustment of
from this curve and from the data available for
the screw II8 to move the fulcrum 96 relative to
on scale” as abscissa. The altitude scale for any
any particular type of bomb with respect to the 30 its lever 96 effects a like adjustment of the ful
relationship existing between time of ?ight T and
crum 91 relative to its lever 9|.
altitude h, for the particular air speed. Thus, the
I provide suitable mechanisms for deducing the
characteristics of the particular type of bomb de
value of tan 0L1‘, i. e., the tangent of the range
termines for any particular air speed S the rela
angle forward, and for continuously comparing
tionship existing between the altitude h and
the value of tan.“ with tan ‘at, as the battle ac
time of ?ight T. Therefore, to determine the alti-‘
tion proceeds, and for deducing the value of tan
tude scale for any particular air speed S it is
?r, the range angle athwartship, and for compar
merely necessary to select points on the above
ing tan 5 with tan ?r continuously as the battle
curve (shown in Fig. 10) so that the ordinates
of the points chosen correspond in seconds to the
times of ?ight for various altitudes at the chosen
air speed. These points projected, as shown, on
the axis of abscissas determine the inches circum
ference on the scale corresponding to the various
altitudes represented by the points selected on
the curve for the particular air speed chosen.
Thus, for example, assume that it is known that
for’ a particular air speed S and for an altitude
of four thousand feet the time of ?ight T is six
action progresses, and when tan or becomes equal
to tan 0L1‘, andif at the same time tan ,8 becomes
substantially equal to tan Br, I cause the bomb to
be dropped automatically or cause a signal to be
given that the proper time for the release of the
bomb has arrived.>
In order to deduce the value tan ctr, I have
provided a suitable differential gear arrange
ment I85 into which is introduced the factor
TV,
h
teen seconds; if a point be selected on the above 50
or its equivalent the tan ar-I-tan trail angle and
curve (Fig. 10) whose ordinate is sixteen seconds
also tan trail angle,‘ the differential being ar
and if this point be projected on the abscissa, the
ranged so that its output measures tan ctr.
portion of a revolution that the scale must be
turned, measured in inches of circumference, in
It will be observed that the setting of the ad
order to bring the fulcrum 96 to such a point 55 justing screw II6, which measures directly tan
ar+tan trail angle, is transmitted to one ele
along the lever 99 that the factor
ment of the differential I85 by means of a shaft
1
I86 to which the screw H6 is suitably connected
by means of bevel gears I81, and a shaft I98 con
is introduced into the lever mechanism is deter 60 nected by bevel gears I89 to the shaft I86 and
by gears I90 to one side of the differential I85.
The’ other differential input shaft I9I is controlled
by means of an adjusting knob I92, and is con
may be calculated. A series of these scales for air
nected with the ‘differential by means of gears
speeds ranging from sixty to one-hundred and
forty knots is illustrated by way of example in 65 I 93'." As shown, the knob I92 is connected directly
‘with the shaft I9I. The adjusting knob I92
Fig. .11, the composite scale being shown as a de+
serves to generate in the differential the value of
velopment of the drum.
the tangent trail angle which is read in terms of
It will be understood that the altitude scales
altitude hon a‘suitable scale I94 selected by the
for the various air speeds as shown in Fig. 11 will
be arranged on the scale in accordance with the 70 proper setting of the adjusting screw I89 to the
value of the air speed S.
“ .
arrangement of the air speed indications on the
The altitude‘ scales of the scale I94 are cali
scale IBI so that when the knob I89 is turned
brated so as to give an indicationof the amount
tobring the index‘ associated with the scale IBI
or portion of a revolution that the scale must be
to any particular air speed, the; proper altitude
scale on the drum I83 will automatically be se 75 rotated inorder to introduce into the mechanism
mined.
Similarly altitude scales for other air speeds
2,408,356
31'
the‘ tangent function of the trail angle correspond
ing to a given altitude and air speed for any par
ticular type of bomb.
1
The movement of the scale I94 to introduce
the tangent function of any particular trail angle
may readily be determinedby assuming that one
32
one-hundred forty knots. It will be understood
that these altitude scales are arranged on the
scale or drum I 94 so that the proper altitude
@scale will be selected automatically when the
bomber sets the adjusting screw I80 to air speed
S of the airplane, and that to introduce the tan
gent function of the trail anglecorresponding to
corresponds to the tangent function of the maxi
the altitude and‘ai'r speed of the airplane, it is
mum trail angle that it is contemplated will have
merely necessary to setthe existing altitude on
to be provided for, and then determining the 10 the selected altitude scale.
fraction of this total motion that the scale must
It will be understood that if different types of
be moved so as to introduce the tangent func
bombs be used altitude scales calibrated in ac
tions of trail angles of lesser magnitude. For the
cordance with the characteristics of the differ
purpose of explanation let it be assumed that the
ent types will be provided.
maximum trail angle to be provided for is 10°47’, 15
The output shaft I95 of thedifferential I85
or in other words, that the maximum tangent
measures the sight offset, tan car. It will be
function to be provided for is .1902, and that one
observed, therefore, that the setting of the ad
revolution of the scale will introduce this func
justing screw I I 6, together with the setting (gen
tion into the mechanism. It will be obvious that
erally at the beginning of the battle action) of
the portion of a revolution that the scale must be 20 the adjusting knob I92 to tangent trail angle
turned so as to introduce the tangent function of
automatically generates in the differential I85
a lesser trail angle will be proportional to the
the tangent of the range angle forward.
ratio of the tangent functions of the lesser trail
As has been pointed out, the setting of the
angle and of the maximum trail angle. Thus
measuring spring III by the adjusting screw II1
for example, the portion of a complete revolution 25 automatically measures the tangent of the range
of the scale corresponding to a trail angle of 5°
angle athwartship, i. e., tan ?r.
The tangent of the range angle forward on is
or more or a portion of a revolution of the scale
1s
.
.0875 (the tangent of 5"‘)
.1902 (the tangent of 10°47’)
subtracted in a differential gear I96 from tan a,
while the tangent of the range angle athwart
which ratio equals .460. In other words, the 30 ship pr is subtracted from tan 5 in a differential
gear I91. It will be observed that the shaft I95,
drum must be turned through .460'of one revolu
which measures tan ctr, is connected to one ele
tion in order to introduce the tangent function
ment of the differential I96 by means of gears
of a 5° trail angle. In like manner the portions
I98, and that the shaft I46, which measures
of a. complete revolution of the scale correspond
ing to other trail'angles to be provided for may 35 tan 0c continuously as the battle action progresses,
is connected with another element of this dif
readily be determined.
ferential by means of a shaft I99. As shown,
The altitude scales of the scale I94 may read
one end of this shaft I99 is connected by means
ily be calibrated by plotting a curve having as
of suitable bevel gears 200 with the tan a shaft
its coordinates, “Degrees trail angle” and “Inches
I46 and its other end is connected by means of
circumference on scale” corresponding to the
gears 20I with the differential I96. The move
tangent functions of the trail angles, it being
ments applied to the differential I96 by the
understood that whether inches circumference on
shafts I95 and I99 are subtracted in the differ
scale or whether portions of a revolution of the
scale be plotted is immaterial. Such a curve is
shown in Fig. 12. As shown, “Degrees trail angle”
is the ordinate, while “Inches circumference on
scale” is the abscissa. In plotting this curve it
is assumed for the purpose of explanation that
the scale has a circumference of ten inches and
that one revolution of the scale, i. e., ten inches
of circumference, corresponds to the tangent
ential so as to measure the difference between
tan a and tan car.
In like manner the tan {3 shaft I4‘! is connected
with one side of the differential I91 by means
of a shaft 202, while the other side of this dif
ferential is connected directly with the adjust~
ing screw II'I through the medium of suitable
gears 203.
The output shafts 204 and 205 of the differen
tials I96 and I9‘! respectively are connected to
10°47’.
With the information which is available for 55 control suitable switching devices 206 and 201
which will serve to control a controlling circuit
any particular type of bomb with respect to the
either for a suitable bomb releasing mechanism
relationship existing between trail angle and alti
(not shown) or for a suitable signal which will
tude for various air speeds the altitude scales may
serve to indicate that the proper time for re
readily be determined from the curve shown in
lease has arrived.
Fig. 12. Thus, for a particular type of bomb and
I have shown diagrammatically in Fig. 5 a con
for a particular air speed S it is merely necessary
trol circuit for a suitable bomb releasing mecha
to select points on the curve shown in Fig. 12
nism (not shown). This circuit as shown com
which points correspond to the trail angles for
prises-a suitable releasing coil 2I0 which when
various altitudes h, the projections of these points
energized operates to effect a release of the bomb.
on the axis of abscissas giving the locations of 65
The coil 2| 0 is energized from a suitable direct
the altitude graduations on the scale for the par
current source of supply 2 I I, the energization of
ticular air speed chosen. I have indicated in Fig.
this coil being controlled by the switches 206 and
12 the altitude scale as thus determined for one
207 so that when both switches are closed, as
air speed. In like manner the altitude scales for
shown in Fig. 5, the coil will be energized to re
various other air speeds may readily be deter 70 lease the bomb. It will be observed that each of
mined.
these switches is provided with a central contact
function of a chosen maximum trail angle of
In Fig. 13 I have illustrated by way of ex
ample a development of an altitude scale I94,
the scale being provided with altitude scales for
a- number of air speeds ranging from sixty to 75
arm 2I2 and with a pair of contact arms 2I3
disposed on opposite sides of the arm 2I2. These
arms 2 I3 are pivotally mounted, as shown, and
are biased by means of a compression spring 2I4
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