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Патент USA US2412585

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CROSS REFERENCE
Dec- 17, 1946-
w. B. KLE_MPERER ET AL
2,412,585
SIGHTING DEVICE
Filed Jan. 12, 1943
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SIGHTING DEVICE
Filed Jan. 12, 1943
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Dec‘ 17, 1946-
w. B. KLEMPERER ET AL
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SIGHTING ‘DEVICE
Filed Jan. 12, 1943
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INVENTORS
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Dec. 17, 1946.
W. B. KLEMPERER ET AL
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SIGHTING DEVICE
Filed Jan. 12, 1943
$725. Z4’.
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2,412,585
Patented Dec. 17, 1946
-UNITED STATES PATENT OFFICE
2,412,585
SIGHTIN G DEVICE
Wolfgang B. Klemperer, West Los Angeles, and
Sydney J. Goldberg, Los Angeles, Calif., as
signors to Douglas Aircraft Company, Inc.,
Santa Monica, Calif.
Application January 12, 1943, Serial No. 472,168
19 Claims. (Cl. 33—46.5)
1
2
Our invention relates to a sighting device and
has particular reference to a device for determin
ing and indicating the release point and the
course to be followed by a projectile launched
from a moving vehicle and intended to strike a
matically so that a minimum number of simple
operations will remain for the pilot to perform.
Prior sighting devices of the character to which
this invention relates were not entirely satisfac
tory in that they either required too much atten
moving target.
tion or work on the part of the pilot as by requir
ing him to perform trigonometrical or nom0~
In the conduct of a war, it is often necessary
to launch an explosive ?lled projectile from a
graphical calculations while using the sight or
moving vehicle such as an aeroplane or boat in
were inaccurate in that they did not take into
such manner that the projectile will collide with 10 account certain of the factors vital to an accurate
a selected target which may be either moving or
determination of the projectile release point and
stationary. In order for the desired collision to
course. The prior devices were also inaccurate
result, it is of course necessary that the projectile
be launched at a predetermined point and in the
in that they required vital factors to be estimated
proper direction, and it is therefore necessary .
computing some of these factors.
or guessed at because no provision was made for
.
that the pilot of the vehicle be provided with
It is therefore an object of our invention to
some means for determining a suitable release
provide an improved sighting device for deter
mining and indicating the proper release point
and course of a projectile to be launched from a
moving vehicle with the intent that it collide with
a selected stationary or moving target.
point and the corresponding course direction of
the projectile.
One of the most important and most complex
problems in this connection is to be found in the
launching of the torpedoes from aircraft with
the intent to torpedo a moving surface vessel
It is also an object of our invention to provide
a sighting device of the character referred to in
the preceding paragraph, which includes a sight
such as a warship. The determination of a suit
able release point and the corresponding torpedo
- ing means for de?ning a sighting line movable
course involves the proper correlation of many
factors, both variable and ?xed, among which
through an angle equal to the angular measure
ment of the apparent distance it is necessary to
may be enumerated
(1) The altitude of the aircraft at the time the
jectile to collide with that target, together with
“lead” a moving target in order to cause the pro
30 a drive means for so moving the sighting means.
torpedo is launched;
(2) The velocity of the aircraft at the instant
It is an additional object of our invention to
of launching;
provide a sighting device of the character set
(3) The torpedo travel range;
forth in the preceding paragraphs which includes
(4) The angular relation between the course
a calculating means for computing the “lead”
of the target and the course of the aeroplane;
angle from known controlling factors, said cal
(5) The speed of the target; and
culating means being operatively connected to
(6) The speed of the projectile.
the drive means for the sighting means to effect
In addition to the problem of properly corre
an automatic moving of the sighting means
lating these and other factors, there exists a fur
through the computed “lead” angle.
ther problem in that some of these factors can
not be directly determined and others are sub
ject to magnitude variations during the time be
tween the launching of the torpedo and its ar
rival at the target location and this requires
the taking into account of still further factors
which can be determined.
To achieve the utmost in accuracy, a sighting
device of this character must provide for a pre
40
It is a still further object of our invention to
provide a sighting device of the character here- ‘
inbefore referred to, which includes a, means for
measuring the angle through which the sighting
device is actually moved, together with a com
paring device for c mparing the
le
mo\e
ment with the computed “lead” angle and so
controlling the driving means as to move the
sighting means in such direction and to such an
cise measurement of the critical factors involved
wherever this is possible and must also provide 50 extent as to establish equality between said
angles.
for a precise mathematical correlation of all of
It is also an object of our invention to-provide
the determined factors. Furthermore, in order
a sighting device of the character set forth in
' that the sighting device may be used by a pilot
the preceding paragraphs, in which the sighting
of an aircraft or other vehicle, it is necessary that
the majority of its functions be performed auto 55 means is releasably connected to the drive means
2,412,585
3
4
to permit the sighting means to be moved inde
pendently of operation of the drive means.
“lead” angle and controls the operation of the
It is a still further object of our invention to
drive means so as'to move the sighting device to
a position corresponding to the computed “lead”
angle, and which also controls the ranging de
vice comprising a part of the sighting device of
our invention;
Fig. 13 is a geometrical diagram similar to
Fig. 2 but illustrating the additional factors relat
provide a sighting device of the character here
inbefore referred to, which includes a selective
control device by means of which the sighting
means may, if desired, be secured to a position
aligning the sighting line with the course of the
ing to the sighting problem occasioned by the
vehicle upon which the device is mounted, or
connected to the drive means, or free for manual 10 aircraft following a "homing path”; and
Fig. 14 is a view similar to Fig. 13 but illustrat
movement to the selected position.
ing one way in which the “homing path” difficulty
It is an additional object of our invention to
may be avoided by following a straight “air in
provide a sighting device of the character set
terception” course.
forth hereinbefore, which includes means for in
dicating arrival of the vehicle at the proper pro 15
General description
jectile release point.
It is an additional object of our invention to
provide a sighting device which can beused as a
torpedo sight as well as a gun sight in conjunc
tion with guns mounted ?xed upon the same air
craft.
Other objects and advantages of our invention
will be apparent from a study of the following
speci?cations, read in connection with the accom
panying drawings, wherein:
Referring to the drawings, we have illustrated
diagrammatically in Fig. 1 the interior of a pilot’s
compartment of an aeroplane as including an in
strument panel I surmounted by a windshield 2
which may be ?tted between the instrument panel
I and a roof or ceiling supporting member 3.
We have shown in Fig. 1 the preferred embodi
ment of our invention as including a sighting
means indicated generally by the reference char
acter 4. This device is preferably mounted for
Fig. 1 is a perspective view of a portion of the
interior of the pilot’s compartment of an air
slidable movement upon a guide rail 5 which is ex
. craft and illustrating in perspective the general
tended laterally across the pilot’s compartment
and supported by a suitably strong and rigid
form and appearance of the preferred embodi
ment of our invention;
Fig. 2 is a geometrical diagram illustrating the
various factors involved in the determination of
the projectile release point and the proper course
transverse member 6. As will be more fully de
scribed hereinafter, the sighting device 4 is slid
ably mounted upon the guide member 5 so that
when not in use it may be positioned at the ex
to be followed by the projectile;
treme side of the pilot’s compartment where it
Fig. 3 is a side elevational view of the sighting :
means portion of the device of our invention;
Fig. 4 is an end elevational view of the device
will be out of the way and so that it may be slid
to any selected operative position such as that
illustrated in Fig. 1 whenever a need for its use
illustrated in Fig. 3;
arises. Such operative position may be straight
Fig. 5 is a fragmentary cross sectional view
taken substantially along the line V--V of Fig. 3
and illustrating certain details of construction of
the drive means employed for the sighting means;
Fig. 6 is an enlarged longitudinal sectional view
taken substantially along the line VI-VI of Fig.
5 and illustrating additional details of construc
tion;
.
Fig. 7 is a fragmentary cross sectional view
ahead of the pilot or somewhat to his right or
left, depending on whether the sight is used as
a gun sight or as a torpedo sight to attack a sur
face vessel approaching from the right or left.
The sighting device 4 includes a pelorus portion
serving to de?ne a line of sight ‘I. The device is
arranged to be angularly moved about a vertical
axis 8 so that the sighting line ‘I may be swung
from side to side as desired. The mechanism of
taken substantially along the line VII—VII of
our invention includes also a manual setting
Fig. 6 and illustrating the details of construc
device or control member 9 to be described in
tion of the selective latching means employed for 50 more detail hereinafter, the control member 9
controlling the permissible movements of the
being normally supported from the instrument
sighting means;
panel I as by means of a bracket So so as to be
Fig. 8 is a cross sectional view taken substan
available for use by the pilot of the aeroplane
tially along the line VIII-VIII of Fig. 6 and illus
at any time. The control member 9 is connected
trating the details of construction of a ranging ,
by means of a cable It) to an electrical calculat
device forming a part of the sighting device of
ing device or computer H which is preferably
our invention;
mounted in some convenient location in the air
craft which need not be a location accessible to
Fig. 9 is an elevational view illustrating the
general form and appearance of a control mem
ber comprising an assembly of control devices
by means of which various determined and se
lected factors involved in the determination of
the projectile release point and course may be
the pilot of the plane.
Calculation of torpedo course
The preferred form of our invention which is
illustrated and described herein is intended for
use as a sighting device for torpedo carrying alr
introduced into the calculating mechanism form
craft and is intended to permit a pilot of such an
ing a part of the device of our invention;
aircraft to control the launching of the torpedo
Fig. 10 is a fragmentary sectional view illus
carried thereby so as to, as far as is possible, start
trating the interior details of construction of the
the launched torpedo along a course which will
control member illustrated in Fig. 9;
Fig. 11 is a diagrammatic view illustrating the
surely effect a collision between the torpedo and
relationships in the various parts and the mode 70 the target vessel.
of operation of the angle measuring instruments
We have illustrated in Fig. 2 by means of a
geometrical diagram the various factors which
included in the sighting means;
Fig. L2‘ is a “block” diagram illustrating the
are involved in determining the proper course to
principle of operation of an electrical calculat
be followed by the torpedo in order to cause a col
ing device of our invention which computes the 75 lision with the target vessel of a torpedo launched
s
1;
5
2,412,585
from a selected release point. It will be noted
that Fig. 2 is drawn in two parts, the upper part
comprising a plan view while the lower part com
prises an elevational view illustrating the path
of the torpedo after it is droped from the air
craft. This ?gure is an approximate representa
tion of the conditions and relationships existing
just prior to the launching of a torpedo in that it
shows as straight lines certain portions of the
6
extended from the release point RP to the cen
ter of the target ship TS when in the position
illustrated by the outline TS’, the sighting line
being disposed at the lead angle ¢> relative to
the course of the plane l2 and the course of the
?ight path of an aircraft which are in prac
torpedo and having a length equal to the sight
ing range Y. The third side of the triangle com
prises the extension of the target ship course I5
extending from the ship position TS’ a distance
D to the collision point 0 and making the angle
tice usually curved. However, as is explained
in detail hereinafter, the simpli?cation effected
by treating these curved paths as straight lines
0 with the sighting line 2|. The third angle of
the triangle is the striking angle or angle of in
tersection of the target course 15 with the tor
introduces an error which is so small as to have
pedo course 18 and is represented as the angle a
.
a negligible effect upon the result obtained.
15 in Fig. 2,
In Fig. 2 it is assumed that an aircraft I2
Reference to the lower half of Fig. 2 will indi
is proceeding along a course indicated by the line
cate the vertical variations in the course of the
l3 at the time a target vessel TS is sighted. The
torpedo after launching. In this portion of Fig.
vessel TS is assumed to be travelling in the di
2 it is assumed that prior to the arrival of the
rection indicated by the arrow [4 along a course 20 aircraft I 2 at the release point RP the aircraft
indicated by the line l5 and at a velocity U.
is ?ying along the course IS with a velocity V
It is assumed that by the time the aircraft l2
at a constant altitude H. When the aircraft ar
has reached the point illustrated in Fig. 2, the
rives at the release point RP the torpedo is re
pilot has determined that the target TS is an
leased and so falls by gravity to the surface of
enemy ship and has determined that he will at 25 the water. In so falling the torpedo pursues a
tempt to sink the target ship TS by launching a
substantially parabolic course such as is indi
torpedo at the same. Accordingly a sight is taken
cated by the curved line 22. The principal di
mensions of this parabolic course comprise the
as illustrated by the dotted line l6 and the target
altitude H at the origin of the curve and the
course line I5 is determined in a manner to be
described hereinafter, this angle being indicated 30 horizonta1 distance 111 through which the torpedo
travels due to its initial forward velocity V dur
in Fig. 2 as the angle 0 and hereinafter referred to
ing the time of fall from the altitude H to the
as the target approach angle. Thereafter the
surface of the water. Upon striking the water
sighting device is employed to compute the lead
the torpedo submerges to a certain depth and
angle which will be hereinafter referred to as ¢.
When this angle is determined, the sighting de 35 then rises to the normal propulsion depth for
which the torpedo was set, this part of the tor
vice is turned astern of the target through the
pedo course being indivated by the double curved
angle Q5 and the course of the aircraft [2 is then
line 23 in Fig. 2. The speed of the torpedo dur
altered as indicated by the curve I‘! in Fig. 2 to
ing this part of its course will for convenience be
swing the course of the plane I2 ahead of the
target through an angle sufficient to again bring 40 represented by the term Va.
After the torpedo has traversed the distance
the sighting line to bear upon the target TS.
d2 it will have decelerated to its normal propul
The procedure just described is one of several
different approach techniques in aircraft torpedo
sion velocity, to which velocity W is assigned.
The remainder of the torpedo travel until the
attacks. It is with reference to this technique
that the function of a sight constructed accord 45 collision point 0 is reached covers a distance d3.
For convenience in calculation we have em
ing to the invention will now be explained but the
ployed the symbols t1, t2, and is to indicate the re
sight lends itself equally well to the use with
spective times required for the torpedo to trav
other approach techniques.
erse the distance d1, (12 and d2.
The new course of the aircraft I2 is indicated
If it were not for the fact that the torpedo
by the line I8 in Fig. 2. The aircraft is, at the 50
traverses the ?rst part (d1) of its path in air
time of torpedo launching, assumed to be trav
at essentially the same speed as the air speed
elling in the direction indicated by the arrow 19 _
(V) of the aircraft and the last part of its path
along'the course l8 and at a velocity V. When
((13) in water at the much lower propulsion ve—
the aircraft reaches the release point RP, the tor
pedo is launched, the release point RP being sit 55 locity (W) of the torpedo, and if it were not for
the fact that the time (in required for the ?rst
uated a distance R (hereinafter termed “the tor
part (d1) of the path does not depend on the
pedo travel range”) from the'point 0 where the
torpedo
travel range (R) whereas the time (ts)
intended collision between the torpedo and the
target vessel TS will take place. At the time the 80 required for the last part (d3) of the path does,
torpedo is launched the target ship TS occupies
the position illustrated in Fig. 2 by the ship out
line bearing the reference character TS’. After
being launched the torpedo proceeds in the direc
the shape of the interception triangle (RP, 0,
TS’) would not be affected by the torpedo travel
range (R) and it would not matter atwhich
range the torpedo was launched provided the
correct value of the lead angle (¢) was used.
tion of the course I8 as indicated by the arrow 65 However, because of the difference in times and
20 in Fig. 2 with a velocity of varying magnitude
velocities just noted, the range, once chosen, does
which may be represented by an average veloc
ity X which is associated with the torpedo travel
range R.
have a corrective influence upon the proper lead
angle. It is therefore necessary to choose a suit
.
able torpedo travel range and then evaluate the
At the instant of torpedo launching there ex 70 lead angle which is associated with the selected
ists a sighting or interception triangle compris
range. The choice of the torpedo travel ,range is
ing the intended torpedo course l8 extending
ordinarily made by the pilot of the aircraft after
from the release point RP to the collision point
appraisal of the tactical situation. It is there
0, this side of the triangle having a length equal
fore assumed for the purpose of this analysis that
to the torepdo travel range R; a sighting line 2| 75 the pilot of the aircraft l2 arbitrarily selects the
2,412,585
7
,
8
of the aircraft rather than its air speed. If the
wind drift triangle is known or is determined in
torpedo travel range R at which the torpedoing
operation will be performed.
It is further assumed that at the time the pilot
of the aircraft l2 decides to attempt to torpedo
the target ship TS the velocity V of the aircraft
and its altitude H are known. It is also assumed
that the normal propulsion velocity W of the tor
correction
?ight in a for
conventional
head or tail
manner,
wind component
an appropriate
may it;
" '
be effected by an appropriate addition to or sub
traction from the observed air speed of the air
craft.
The transverse component or cross wind can
pedo is known, that the deceleration time t2 of
the torpedo has been previously determined, and
perhaps best be compensated for by so side-slip
that the pilot of the aircraft 12 having observed 10 ping the aircraft into the wind as to assure yaw
less entry of the torpedo into the water, although
the target ship TS is able to recognize the nation
other corrective measures may be adopted as
ality and type of ship and from the manner in
which it is travelling through the water is able
desired.
The velocity Va which has been assigned to the
to determine from data previously compiled the
probable value of the velocity U of the target 15 torpedo during the time t2 may, inasmuch as
this time it is thereby de?ned, rbe taken as an
ship TS.
average of the initial and terminal torpedo veloc
Having determined these various factors, the
pilot sets the angle 6 on the sighting device of our
ities. In other words
invention and effects an automatic calculation of
Va=1/2(V+W)
(10)
the lead angle ¢. The basis for this calculation 20
may be readily understood from the following
The
distance
(12
may
be
expressed
in
terms
of
analysis.
the average velocity Va. and t2 (which is assumed
It is obvious that in order to effect the desired
to be known from experiment) thus:
collision between the torpedo and the target ship
TS the time which is required for the target ship 25
to travel from the position TS’ to the collision
The remaining terms its and d3 may be expressed
point 0 must necessarily equal the time required
in terms of the propulsion velocity W and the
for the torpedo to travel from the release point
range R and the remaining distances di and (12.
RP to the collision point 0. Using the symbol T
Substituting the above indicated values of d1,
to represent this time, it may be said that
T=D/U=R/X
d2, da, t1, t2 and t: in Equation 7 gives
' (1)
From this it may be said that
D/R=U/X
X
(12)
(2)
35
From the law of sines, it may be noted thatv
D/R=sin ¢/sin 0
(3)
sin qs/sin 0=U/X
(4) 40
Substituting this expression for X in Equation
5, supra, gives for the determination of ¢> the
followingexpression
and, therefore,
and
sin ¢=g§—n0
(5)
erated variables. Other problems involving dif
ferent factors or the taking into account of addi
tional variable factors will, of course, change the
equation derived. It will be realized, however,
permit the calculation of the angle 45. X, it will
be recalled, is the average velocity of the torpedo
in traversing the torpedo travel range R from
the release point RP to the collision point ll. Thus
X=R/T
(6)
This may be written
r___dl+d2+d3
(7)
(13)
The foregoing derivation is given as an exam
ple of one sighting problem involving the enum
Since U and 0 are both determined quantities,
it is necessary only to evaluate X in order to
A- t1+t2+$3
sin 0
that in such event the principles and the funda
mental relationships are the same as described.
From the foregoing it is apparent that the de
termination of the angle <p depends upon deter
mining and properly correlating the velocities U,
V and W, the distances H and R, the time t2 and
the setting of the angle 0- The manner in which
I
these various factors are correlated and the man
ner in which the angle 0 is set on the sighting de
vice will become apparent as the description of
since the sum of the distances d1, d2 and d3 equals
the distance R, and the sum of the times t1, t2
the device proceeds.
and t3 equals the total time T.
The sighting mechanism
The time n is the time required for the tor 60
Figs. 3 through '7 illustrate the details of con
pedo to fall from the altitude H to the surface
struction of the actual sighting mechanism por
of the water. Thus
tion of the sighting device of our invention. As
is best shown in Fig. 6, the sighting mechanism‘
where g is the acceleration of gravity. The dis
4 includes a bracket 24 fitted with guide mem
tance d1 may be expressed in terms of the forward
bers 25 and 26 adapted to engage the guide rail
component of velocity of the torpedo and the
5 in such manner as to accurately maintain a
time ti as
predetermined alignment between the bracket 24
and the guide rail 5.
Preferably the bracket 24 supports a mecha
In the preceding equation, the forward com 70
nism permitting the bracket to be immovably
ponent of velocity of the torpedo has been taken
clamped to the guide rail 5 or released therefrom,
as equal to the velocity V of the aircraft. This
as desired, to permit the bracket to be slid along
is suf?ciently accurate for all purposes when
the length of the guide rail. This mechanism
there is no wind. However, if there is a wind, the
term V must be used to express the ground speed 75 may include a spring handle 21 secured to a
2,412,685
transverse shaft 28 suitably journalled in the
bracket 24. Upon the shaft 28 there is mounted
a cam member 29 so positioned as to dispose a
cam face 30 adjacent and parallel to one of a
10
through the center of the reticule 69 will strike
the center of the mirror 49 and be re?ected
thereby along the optical axis 48 of the lens 46.
Below the lens 46 there is positioned a partially
pair of inclined surfaces 3| formed on the guide
re?ecting mirror 62, the same being mounted in
rail 5, the other of said pair of surfaces 3| being
a suitable mounting bracket 63 which is pivotally
engaged by an adjustable shoe 32. A torsion
secured to the forward edge of the housing por
spring 33 looped behind the cam 29 and engaged
tion 44 as by means of a pivot shaft 64. The
with the bracket 24 normally urges the cam face
partially re?ecting mirror 62 is normally disposed
30 into pressure engagement with the adjacent 10 at an angle of approximately 45° relative to the
inclined surface 3| and so clamps the guide rail
optical axis 48 of the lens 46 so that as the pilot
5 against the guide members 25—26 and the
or the user of the sighting device looks along
shoe 32 to thereby lock the bracket 24 against
the sighting line ‘I he will see through the mirror
movement along the guide rail 5. Movement of
62 any objects which may be located on the ex
the handle 21 in a counterclockwise direction as 15 tension of the sighting line 1 and will see also the
viewed in Fig. 6 overcomes the spring 33 and
re?ection from the surface of the partially re
moves the cam face 30 away from the rail 5 and
?ecting mirror 62 the image of the reticule 60
so releases the bracket 24 for free sliding move
as reflected by the mirror 49 and transmitted by
ment along the rail 5.
the lens 46.
_
The construction just described allows the 20
The lens 46 is positioned a distance equal to
sighting means 4 to be slid to one side; out of
its focal length from the reticule 60 so that the
the way, and allows it to be moved into and
image of the reticule seen by the pilot in look
locked in an operative position when its use is
ing along the sighting line ‘I will appear to be
desired. This mechanism also permits lateral
located a great distance away. This serves to
adjustment of the position of the sighting means
superimpose upon the object actually seen
4 when in use so that the pilot of the aircraft
through the partially re?ecting mirror 62 the
may move the sighting means 4 to one side or
greatly magni?ed image of the reticule 69. The
the other of a position directly in front of his
reticule 69 preferably includes cross-hairs or like
head to thereby relieve the pilot of the necessity
representations which de?ne the axis of the sight
of moving his head to one side or the other when 30 ing line and the parts are so collimated that the
sighting at an angle to his own ?ight path in an
apparent superimposition of the reticule cross
attack upon a target vessel moving either toward
hairs upon the object actually situated on the
the right or left of his own original course.
sighting line will occur precisely at the inter
The bracket 24 supports a ?xed member 34
section of the sighting line with the object, inde
which is of inverted cup-shaped form, being -. CA pendently of whether the observer’s eye is slightly
characterized by an open bottom and a hollow
displaced from the optical axis 1 within the aper
interior de?ning an interior space 35. The open
ture of re?ected image of the lens 46.
bottom of the member 34 supports a journal ring
It will be appreciated, of course, that if the
36 which may be secured to the ?xed member 34
device described is mounted on an aeroplane
as by means of threads 31. The journal member 40 ?ying at a considerable altitude and it is desired
36 coacts with a similar journal member 38 which
to take a sight on a surface vessel under circum
is secured as by means of threads 39 to a hous
stances making-it undesirable to depress the nose
ing portion 40 of the sighting device, thus jour
of the aircraft, it will be necessary to depress
nalling the housing portion 46 for pivotal move
the line of sight below the horizontal to an
ment about a vertical axis 4|. The journal 45 inclined line la which is illustrated as a dotted
members 36 and 38 may be locked to the housing
line in Fig. 6. On the other hand, it is intended
member 40 as by means of lock rings 42.
that the sighting means 4 be used alternatively
The housing member 40 in turn supports the
as a torpedo director or as a sighting device for
pelorus portion of the sighting device, which por
aiming ?xed guns mounted on the aircraft to
tion includes an angled housing 43 comprising a 50 ?re forward in a direction substantially parallel
vertically disposed portion‘ 44 and an angularly
to the axis of the plane. It is, therefore, desir
disposed portion 45.
able to provide an adjustment means whereby the
The lower end of the vertical housing portion
direction of the substantially horizontal sighting
44 is open and a lens 46 is secured therein as
line 1 may be adjusted vertically to bore-sight
by means of the usual threaded mounting ring 65 the ?xed guns and it is also desirable to provide
41. The lens is positioned with its optical axis
an indexing means to permit the bore-sighted
48 vertical in a position to intersect the center
line 1 to be re-established as desired after being
of a re?ector or mirror 49 positioned behind an
depressed to the inclined line ‘la as described.
opening 59 formed in the upper part of the hous
For these reasons, the pivot shaft 64 also piv
ing 43 and covered as by a cover 5|.
60 otally supports an upwardly directed adjustable
From the outermost end of the angled hous
stop member 65 which is apertured to receive a
ing portion 45 a bracket 52 extends which sup
screw 66 secured to a suitable boss 61 provided
ports a lamp socket 53 carrying an incandescent
on the housing portion 44. Adjusting nuts 68
electric lamp 54. The socket 53 and lamp 54
are threaded upon the screw 66 on opposite sides
are enclosed by an openable cover 55 hingedly 65 of the stop member 65 to permit adjustment of
secured as at 56 to the end of the housing por
the angular position of the stop member 65. The
tion 45 and adapted to be held in its closed posi
stop member 65 also extends downwardly along
tion as by means of a spring grip 51.
side the mirror bracket 63 and provides near its
The outermost end of the inclined housing por
lower end a stop surface 69 which is engaged
tion 45 is closed by an end wall 58 which is pierced 70 by the peripheral surface of an eccentric mem
with an aperture 59 in which is mounted a recti~
ber 10 pivotally mounted upon the bracket 63.
cule 60. the latter being held within the open
A torsion spring 1| (Fig. 3) surrounding the shaft
ing 59 as by means of a mounting ring 6|. The
64 and inter-engaging the bracket 63 with the
recticule 60, lamp 54 and mirror 49 are so posi
stop member 65 serves to continuously urge the
tioned that light projected from the lamp 54 75 mirror bracket 63 upwardly to at all times main
2,412,585
11.
12
tain the eccentric 10 in engagement with the stop
surface 69. A spring and notch arrangement ‘I2
permit the pelorus portion thereof to be turned
or other suitable detent construction is employed
to index and yieldably hold the eccentric mem
to a position not substantially aligned with the
axis of the aircraft, we provide a control knob 92
which is secured to a control shaft 93. The shaft
93 extends into the interior 35 of the ?xed mem
ber 34 and is journalled in the member 34 as by
means of a sleeve bearing 94.
Upon the inner end of the shaft 93 we affix a
ber 10 in a normal or bore-sighted position such
as is illustrated in Fig. 6. A handle 13 permits
the eccentric ‘I0 to be manually rotated in a
clockwise direction and the eccentric member 10
cam 95 which provides a rear cam face 96. This
is so positioned that such rotation will decrease
the distance between the pivot and the periph 10 face engages the inner vertical surface of the
spring member 90 and is so arranged that when
eral surface of the eccentric member ‘I0, thus
the the knob 92 is turned from the position illus
allowing the spring ‘II to move the mirror bracket
63 upwardly and effect a depression of the sight
ing line 1 to a position such as that occupied,
. for example, by the line la.
The adjusting nuts 68 are employed to adjust
the vertical position or direction of the sighting
line ‘I when the eccentric member is in its nor
mal or bore-sighted position to thereby sight in
the ?xed guns of the aircraft, and the detent ar
rangement ‘l2 insures the re-establishment of this
adjustment after the eccentric is rotated to de
press the line of sight.
If desired, the pivot shaft 64 may also pivotally
trated in Fig. 6 through 90°, the spring member
90 will be urged rearwardly or to the right as
15 viewed in Fig. 7 a distance sufficient to withdraw
the projection 89 from the notch 88 and thus re
lease the pelorus portion of the sighting device.
Provision has been made for setting the ap
proach angle 0; that is, the angle between the
20 sighting line and the course of the target ship.
This provision includes a target course arm 91
which is positioned immediately below a bottom
closure 98 for the housing portion 40. The arm
91 is secured to a shaft 99 which is preferably co
support a bracket 14 upon which is mounted a 25 axial with the vertical axis 4I about which the
pelorus portion of the sight is pivotally mounted.
polarizing ?lter ‘I5, permitting the ?lter 15 to be
swung to a position such as that illustrated by the
Within the interior space defined by the hous
solid lines in Fig. 3 to provide for better sighting
ing 40, we mount four rotary transformers iden
in those instances where the glare from the sur
ti?ed, respectively, by the reference characters
face of the water is a considerable hindrance.
30 IOI, I02, I03 and I04. As will be more fully ex
plained hereinafter, each of the transformers
Since, as above stated, it is intended that the
device be used as a ?xed gun sight as well as a
IOI—I04 comprises a primary winding and a sec
torpedo director, it is therefore necessary also
that provision be made for indexing the sighting
ondary winding, the secondary winding being ar
ranged as a stator and the primary winding being
device in such manner as to substantially align 35 arranged as a rotor, the latter being mounted for
angular movement within the stator windings.
the sighting line ‘I in a horizontal plane with the
The transformers are so constructed that when
axis of the aircraft, it being recalled that the
a ?xed voltage is applied to the primary windings,
housing 40 and the pelorus portion enclosed by
the voltage induced in the secondary windings
the housing portion 43 are mounted for pivotal
movement relative to the aircraft about the ver 40 will vary in direct proportion to the sine of the
angle through which the rotor is turned. The ro
tical axis 4| by means of the coacting journal
tors of the transformers I02, I03 and I04 are me
members 36 and 38.
Accordingly, the housing portion 4o is extended
chanically interconnected with each other and are
upwardly into the space 35 within the interior
in turn connected to the shaft 99 so that the
position of the rotors of these three transformers
of the ?xed member 34. Upon the upper end of
relative to the pelorus portion of the sighting
the housing member 40 we secure, as by means
means is de?ned by the angular position of the
of screws, a mounting plate 16. The mounting
target course arm 91.
plate ‘I6 is journaled and threaded to receive a
In operation the sight is ?rst trained on the
journal member 16a. within which an upper notch
target ship, or alternatively the sight may be
plate 17 is journalled as by the extension of a boss
locked in a position aligning the sighting line 1
portion 18 thereof into a guiding aperture ‘I9
formed in the journal member 16a. The notch
with the axis of the aircraft and the aircraft so
plate ‘H is best illustrated in Fig. 7 as comprising
guided as to extend the sighting line 1 to the
target ship. The target course arm 91 is then
a semi-circular, disk-like portion 80 and a for
wardly extending tailpiece SL
55 turned to a position which in the best judgment
The tailpiece 8| is disposed between a pair of
of the pilot of the aircraft aligns the target course
arm 91 with the observed course being pursued by
adjusting screws 82 and 83 threaded in boss por~
the target ship. Experience has proven that the
tions 84 and 85, respectively, formed on the
pilot of an aircraft can, by visual judgment,
mounting plate ‘I6. Access to the screws 82 and
83 may be had through suitably positioned aper 60 readily position the target course arm 91 in paral
lelism with the course of the target ship with suf
tures 86 and 81 provided in the ?xed member 34.
?cient accuracy to keep the calculated value of
A notch 88 formed in the peripheral edge of the
the lead angle 0 within the permissible limits of
plate 1‘! is positioned to receive a locking projec
error.
tion 89 formed upon an upper spring ?nger 90
The stators of the transformers I03 and I04
secured as by means of screws 9| to the ?xed 65
are mechanically connected to each other and
housing portion 34 when the pelorus portion of
to a sleeve I05 which is in turn ?tted into an
the sighting device is turned to a position sub
aperture provided in the lower closure 98. This
stantially aligning the sighting line ‘I with the
serves to hold the stators of the transformers I03
axis of the aircraft. In this position the projec
tion 89 and notch 88 serve to hold the pelorus 70 and I04 in alignment with the pelorus portion
of the sighting means while screws I05a extend
portion against rotation. The adjusting screws
ing through the bottom wall of the lower closure
82 and 83 permit shifting this indexed position
for the purpose of bore sighting the ?xed guns of
98 and into the stator of the transformer I04
the aircraft with respect to the horizontal plane.
hold the stators I03 and I04 against rotation rel
To permit unlocking of the sighting device to 75 ative to the pelorus. Thus the above described
‘aroma
2,412,685
’
13
operation of turning the target course arm 91 to
parallelism with the course of the target ship
vided in a thickened portion of the upper notch
plate 11 so that tightening the plug H4 in its
serves to rotate the rotors of the transformers
threads will contract the same about the shaft
II 3 and secure the same to the notch plate 11.
Initial adjustment of the position of the shaft I I3
I03 and I04 through an angle equal to the target
approach angle.
The manner in which the re
sulting voltage output of the transformers I03
and I04 is employed will be explained in detail
hereinafter.
may be facilitated by the provision therein of a
screw-driver slot H6.
The notch plate 11 also provides an upper coni_
The stators of the transformers IOI and I02
cal surface II1 forming a Part of an upper bear
are mechanically connected to each other and are 10 ing construction, the other part of which com
also secured to a worm wheel I06. The worm
prises a conical bearing surface II8 formed on
wheel I06 and the stators of the transformers
an upper bearing member II9 pressed or other
IOI and I02 are journalled for rotation relative
wise secured in an aperture I20 formed in the
to the stators of the transformers I 03 and I04
and relative to the pelorus portion of the sight
ing means by means of a. ring-like journal I01.
This permits the stators of the transformers IOI
and I02 to be rotated independently of the trans
formers I03 and I04.
?xed member 34. Access to the screw-driver slot
15 II6 may be had through a bore I2I in the bear
ing member I I9 by removing a removable closure
I22.
In order to permit the pelorus portion of the
sighting device to be turned manually to a de
It is intended that the amount of angular 20 sired angular position, we mount within the
movement normally imparted to the stators of
housing 40 a worm gear I25 (see ‘Fig. 5) which is
the transformers I0! and I02 relative to the
supported upon a shaft I 26 suitably journalled
pelorus portion be equal to the lead angle ¢ and
within the housing 40 and so positioned as to
that these transformers be so arranged as to per
engage the worm gear I25 with the worm wheel
mit the pelorus portion of the sighting means to 25 I06. The rearward end of the shaft I26 carries
be turned to and indexed in a position such that
a gear I21 (see Fig. 4) which meshes with a gear
the angle between the sighting line ‘I and the axis
I28 mounted upon a stub shaft I29. The stub
of the aircraft be equal to the amount of angular
shaft I29 carries an adjusting wheel or crank I30
movement of the stators of the transformers IOI
by means of which the shaft I29 may be rotated.
and I 02 to the pelorus portion of the sighting 30
It will be seen that rotation of the crank I30
device.
will effect a relative rotation between the hous
For this purpose we secure to the upper end of
ing 40 and the worm wheel I06. If the worm
the stator of the transformer IM a notch plate
wheel I06 and the stators of the transformers IM
I08. This plate is provided on its upper surface
and I02 to which it is connected are held against
with an annular groove de?ning a tapered jour
rotation by engagement of the projection III
nal surface I09 which coacts with a similar sur
with the notch IIO of the notch plate I08, this
face formed on the under side of the journal
relative rotation appears as a rotation of the
member 16a and serves as a journal coacting with
the journal I01 to support the transformer stators
IOI and I02 for rotation within the housing 40.
The notch plate I08 is provided with a notch IIO
adapted to receive a projection III formed on a
spring ?nger II2 secured to the ?xed portion 34
of the sighting device and positioned immediately
below the shaft 93 in a position to be engaged by
the cam surface 96 of the cam member 95.
As clearly appears in Fig. 6, the cam surface
96 is so arranged that when the knob 92 is in the
position shown in Fig. 6, the upper notch plate
11 will be locked to the ?xed housing portion 34;
when the knob 92 is rotated through 90° from the I
position illustrated in Fig. 6, the spring ?nger
90 will be withdrawn and the spring ?nger II2
will be held withdrawn so that neither the notch
plate 11 nor the notch plate I08 will be held ?xed
relative to the ?xed portion 34 of the sight; and
when the knob 92 is rotated 180° from the posi
tion illustrated in Fig. 6, the upper spring ?nger
90 will be held withdrawn and the lower spring
?nger II2 will be released to allow the projection
III to enter the notch H0 and lock the pelorus
portion of the sighting device in such a position
that the sighting line 1 makes an angle with the
axis of the aircraft equal to the angle through
which the stators of the transformers IOI and
I02 have been moved relative to the pelorus por
housing portion 40 about the vertical axis 4 I.
It is intended that this angular movement of
the pelorus portion of the sight be effected auto
matically and for this purpose we have mounted
within a housing I3I secured to the housing por
tions 40 and 44 a small electric motor, the arma
ture shaft I32 of which carries on its upper end
a worm gear I33. The worm gear I33 meshes
with a worm wheel I34 secured to a stub shaft
I 35. The stub shaft I35 is journalled for rota
tion in a support member I36 and carries on its
rearward end a friction disk member I31. The
friction disk member I 31 coacts with a friction
plate I38 which is slidably mounted upon the
shaft I26 and urged toward the disk I 31 as by
means of a spring I39.
Friction material I40 in
terposed between the members I 31 and I38 in
sures transmission of sufficient torque between
the stub shaft I35 and the shaft I26 to effect
rotation of the sight as above described.
The provision of the friction drive between the
motor and the shaft I26 permits the sight to be
turned through energization of the motor and
also permits the sight to be turned manually
through rotation of the crank I30, in which 1at~
ter event rotation of the shaft I26 is permitted by
slippage at the friction drive element I31-I38.
The structure above described permits either
of two modes of operation of the sighting device.
tion.
For example, the pelorus portion of the sighting
The rotor of the transformer IOI is intended to
device can be locked to the stators of the trans
be held ?xed relative to the pelorus portion of the
formers IOI and I 02 by turning the knob 92 to
sighting device and-is accordingly secured to a
70 the appropriate position. The crank I30 or,
vertically rising shaft I I3 which extends upward
alternatively, the motor I32 may be operated to
ly through an aperture provided in the upper
effect angular movement of the sighting device.
notch plate 11 and is received in a split tapered
According to another modewof operation, the
threaded plug member H4. The plug member
knob 92 may be turned to a position in which
I I4 is threaded into a threaded tapered bore pro 75 the pelorus portion of the sight is disconnected
2,412,585
16
15
calibrations are adapted to coact with suitable in~
dex marks formed on the stationary cylindrical
The crank I30 or the motor I32 may be operated
portions of each of the units to permit the po
to rotate the stators of the transformers MI and
tentiometers to be set in accordance with the
I02 through the desired angle. Thereafter the
knob 92 may be turned to a position releasing CI determined magnitude of certain of the terms
of the lead angle equation, one of such index
the spring ?nger H2, whereupon the projection
marks being indicated by the reference charac
III will engage the periphery of the notch plate
ter I65 in Fig. 9.
I08. The sight may then be grasped by hand and
As clearly appears in Fig. 9, one end of the
manually turned about the axis 4| until the
proper angular position is reached, at which time 10 housing I4! is provided with means for attach
the spring ?nger I I2 will move the projection I II
ment to the control member 9 of the multi-con
into the notch I I0 and lock the pelorus portion
ductor electric cable I0, the various wires of
of the sight in the desired angular position.
which are connected in a manner to be described
Preferably, the lower part of the housing 40
hereinafter to the various terminals of the po
is provided with a protractor scale I23 adapted
tentiometers housed in the control member 9.
The control member 9 has been described as
to coact with a suitable index carried by the
providing for the setting of ?ve separate variable
target course arm 91 to permit direct reading of
the approach angle 0. Similarly, the ?xed por
quantities, i. e., those required for the solution of
the particular sighting problem which has been
tion 34 may carry a protractor scale I24 adapted
to coast with a suitable pointer carried by- the 20 herein described as one speci?c example. It will
movable housing portion 40 to permit direct
be understood that a greater number or fewer
reading of the angle through which the pelorus
potentiometers may be housed within the con
portion is turned. These protractor scales per
trol member 9, depending upon the particular
type of problem to be solved and the number of
mit settings to be made in accordance with men
tal trigonometric calculations for special prob 25 variables to be taken into account.
lems for which the electrical calculating device
The electrical calculation of Q5
may not be adjusted or in the event the electrical
The third portion of the mechanism of our
apparatus fails.
invention comprises an electrical calculator by
The manual setting device
means of which the lead angle as is automatically
In addition to the sighting device just de
computed. Fig. 12 of the drawings comprises a
scribed, the mechanism of our invention includes
block diagram illustrating the principles and
from the stators of the transformers IM and I02.
the manual setting device or control member 9
mode of operation of a calculator which may be
by means of which the magnitude of certain of
used to determine the angle <71» and control move
the terms of the lead angle equation may be ad 35 ment of the pelorus portion of the sighting device
through that angle.
justed. This member is illustrated in detail
In Fig. 12 each of the rectangles is intended
in Figs. 9 and 10. As is shown therein, control
member 9 includes an outer housing or case I4I
to represent an electronic or vacuum tube unit
comprising a hollow cylinder within which there
such an as oscillator, a mixer stage, an ampli?er
are mounted ?ve control units I42, I43, I44, I45 40 stage or the like. The “variable resistance”
symbol has been employed to represent the
and I46. The interior space de?ned within the
housing MI is divided into separate cells, one for
potentiometers of the control member 9 and the
“variable inductance” symbol has been employed
each of the control units I42-—I46, by trans- ‘
versely extending web members I47. The hous
to represent the variable ratio transformers
ing I 4| is cut away as indicated at I5I in Fig. 9
IOI—I04. The lines with the arrowheads affixed
at the location of each of the cell-like spaces de
thereto and extending between the various parts
fined by the web members I41, the apertures I5I
of the apparatus indicate the course of an elec
serving to provide access to dial members I52
trical signal through those various parts. The
mounted within each of the cell-like spaces in
various legends inscribed near each part of the
the housing MI. Each of the web members I41 ' apparatus indicate the mathematical function
is bored centrally as indicated at I54 to receive
performed by that portion of the apparatus and
the mounting sleeve portion I55 of an electrical
the matter inscribed in the rectangles is in
potentiometer of conventional construction and
tended to represent the character of the elec
referred to generally by the reference character
tronic equipment designated by the associated
rectangle.
I56.
The potentiometers I56 may each be immov
As clearly appears from Fig. 12, the calculat
ably secured to an associated web I41 as by means
ing device includes ?rst a source I61 of alternat
of a clamping nut I51 threaded on to the sleeve
ing potential of constant voltage and frequency.
I55. Each of the potentiometers I56 includes a
We prefer to employ for this a vacuum tube
resistance element I58 which is secured within a GI) oscillator normally operating to generate an
stationary housing portion I59. The resistance
alternating potential having a frequency of the
element I58 is engaged by a contact ?nger I60
order of magnitude of one thousand cycles, al
which is mounted upon an insulating plate IBI
though other well known types of alternating
secured to a shaft I62 journalled in the sleeve I55.
potential generators may be used as desired. The
The dial members I52 above referred to may
voltage generated by the source N51 is applied
be secured to their respective insulating plates
as indicated at I68 to the input of the rotary
IBI as by means of rivets I63 so that rotation of
transformer I04. Since the transformation ratio
the dial member I52 effects a relative movement
of this transformer is directly proportional to
between the movable contact I60 and the sta
the sine of the angular displacement of the mov
tionary resistance strip I58.
70 able winding, the voltage output of the trans
To facilitate such rotary movement of the dial
former I04 is likewise proportional to the sine of
member I52, the same is preferably provided with
the angle through which the rotor of the trans
a raised and knurled portion I64. The cylindri
former is turned.
cal portion of the dial member I52 is adapted
Thus, if we assume a maximum transformation
to be calibrated as is indicated in Fig. 9 and these 75 ratio of one to one and assume that the source
I
17
2,412,585
I61 generates a voltage E, then the output of
the transformer I04 will be
e1=E sin 0
(14)
This output is fed as indicated at I69 to a poten
tiometer I10 comprising the unit I44 of the con
trol member 9. The associated dial IE4 is so
calibrated that with the voltage e1 applied across
the entire resistance strip, the voltage between the
movable contact and one end of the resistance
strip will be
18
The dial of this potentiometer is calibrated in
terms of R, the intended torpedoing range. This
calibration is so arranged that the voltage output
of the potentiometer I11 is
68:67/RK4
(22)
The voltage 68 is fed to an ampli?er stage I18,
the overall gain of which is adjusted to be equal
to K. Thus the voltage output of the ampli?er
I18 is
e9: E(U/W) (V- W)
sin 0 (23)v
where U is the velocity of the target ship, W is
the normal propulsion velocity of the torpedo and
The voltage e9 is fed to a mixer stage I19 as is
K1 is the calibration constant of the potenti 15 also the voltage 63 as is indicated at I80. The
ometer I10. Thus the voltage between the mov
able contact and one end of the resistance strip
of the potentiometer I10 is
outputs of the ampli?ers I12 and I18 are so ad
justed with respect to the time phase of their re
ampli?er stage I12, which is preferably of the
910: E(U/W) sin 0»—
spective output voltages that the mixer I19 effects
e2=E(U/WK1) Sin 0
(16) 20 a subtraction of the voltage 69 from the voltage
es. Thus the voltage output of the mixer I19 is
This voltage is fed as indicated at IN to an
electronic or vacuum tube type and which may
be of conventional design and construction, as
may all of the ampli?ers and electronic circuits
referred to hereinafter. The ampli?er I12 may
be adjusted to provide an overall gain equal to
K1 and it will, for the purpose of this descrip
tion, be assumed that it is so adjusted. However,
as will more fully appear hereinafter, the gain
equal to K1 may be obtained in any one or all
of a number of the ampli?er stages employed,
but an understanding of the operation of the
device is facilitated by considering the entire gain
of K1 to be obtained in the one ampli?er stage
I12. The same considerations also apply to the
gain of various other ampli?er stages to be re
ferred to hereinafter. Thus the output of the
ampli?er I12 is
es=E(U/W) sin 0
(17)
The voltage 63 is fed to a potentiometer I13
1
1
E(U/W)(V— W) [hail/9115MB] sin 9 (24)
This expression may be rewritten as
-
Y’
t
a
e—_—E(U/IV)|:1_(_V_M(%1l§D—+:Ll]Sin 9 (25)
Comparing this with Equation 13, supra, it will
be noted that
(26)
It should at this point be noted that among
other things the potentiometer I10 operated to
introduce the factor (l/K1) into the expression
for ex.
This was assumed to be cancelled-out
by introducing the factor (K1) into the expres
sion by making the gain of the ampli?er stage I12
40 equal to K1. It will be apparent that if desired,
the same result may be obtained by making the
product of the gains of the ampli?er I12 and that
input channel of the mixer stage I19 which is
comprising the unit I43 illustrated in Fig. 9. The
associated with the potential e3 equal to Kl. Thus
dial of this potentiometer is calibrated in terms
of V, the velocity of the aircraft and the cali 45 if desired the entire gain of K1 may be had at
the mixer stage I19 if desired.
bration is so arranged that the voltage output
of the potentiometer I13 is
Similarly, there has been introduced into the
expression for eg the factors (1/Kl),(1/K2),(1/K3)
and (l/Ki). The e?ect of these factors may be
This voltage is applied to an ampli?er stage I14 50 cancelled by making the product of the gains of
whose overall gain is eoual to K2. Thus the out
the ampli?er stages I12, I14, I16, I18 and that
put of the ampli?er I14 is
input channel of the mixer stage I19 which is
associated with the potential es equal to
The voltage 65 is fed to a potentiometer I15
comprising the unit I42 illustrated in Fig. 9. The
dial of this potentiometer is calibrated in terms
of H, the altitude of the aircraft, and the cali
bration is so arranged that the voltage output
of the potentiometer I15 is
thus permitting wide choice as to the gains of the
individual stages.
The output of the source IE1 is also conducted '
as indicated at I8I to this input of the rotary
(it) transformer I M. It will be recalled that the
stator of this transformer is adapted to be latched
(20)
to the ?xed housing portion 34 of the sighting
device and that the relative angular positions of
In this expression g is the acceleration of grav
the rotor and stator of the transformer IOI cor
ity and t2 is the deceleration time of the torpedo
responds precisely to the angular position of the
measured from the time it strikes the water until
pelorus portion of the sighting device when the
it slows down to its normal propulsion W, the
notch plate I08 is locked to the ?xed housing
time 132 being determined empirically.
portion 34 by proper manipulation of the knob
92. Thus the angle through which the rotor and
stator of the transformer IOI are rotated rela
age output of the ampli?er stage I16 is
tive to each other represents the angle through
which the sighting line 1 has been revolved with
respect to the axis of the aircraft. This, the
‘The voltage e-: is fed to a potentiometer I11
actual angular movement of the sighting device
comprising the unit I48 illustrated in Fig. 9. 75 will be referred to as the angle ,6. Thus if the
The voltage 86 is fed to an ampli?er I16 hav
ing an overall gain equal to K: so that the volt
2,412,585
19
-
20
voltage input to the transformer IOI is equal to
E, the output voltage is
It will be noted that the pilot of the aircraft
may e?ect this automatic setting of the sight
ing device by performing the following opera
el1==E sin 5
(2'?)
tions. Upon observing the target ship TS, the
The voltages em and cm are each fed to a
sight is brought to bear on the target ship TS.
This may be accomplished by any one of three
mixer I82 and the phase relation of the voltages
different operations; (a) the pelorus portion of
the sight may, by manipulation of the knob 92, be
a subtraction of these two. By this the voltage
latched to the lower notch plate I08 and the
output of the mixer I82 is made
10 hand crank I38 operated to turn the sight,
(b) the knob 92 may be moved to its neutral po
(28)
e12=E (sin ¢—sin p)
sition and the pelorus portion of the sight may
The voltage output an is ampli?ed by a power
be grasped and turned by hand, or (c) the sight
ampli?er I83 and applied to a phase selector I84
may be aligned with the axis of the aircraft as
and polarized relay I85. Referring to Equation 15 by turning the knob 92 to the position illustrated
28, supra, it will be observed that if the angle 5
in Fig. 6 to latch the sight to the ?xed portion
is smaller than the angle ¢, the potential e12
34 and the aircraft so guided as to bring the sight
will be expressed with a plus sign, whereas if
to bear on the target ship.
the angle 5 is increased suf?ciently to exceed the
While the sight is held on the target ship TS,
angle (p, the sign of 612 will change from plus to
20 the target course arm 91 is turned to parallelism
minus. Because era is the magnitude of an alter
with the estimated course of the target ship TS.
nating potential, the plus and minus signs just
The sight is then released as by turning the knob
referred to are meaningless as regards polarity of
92 to a position displaced 90° from that illus
the potential except at a given instant. Thus, in
trated in Fig. 6. Thereafter the pilot, having rec
reality, a change in sign from plus to minus (or
ognized the nationality and type of the target
vice verse) of the voltage e12 signi?es a complete 25 ship TS, may from his own knowledge set the
180° reversal in the time phase of the voltage.
potentiometer H0 to a point corresponding to the
The phase selector I184 is arranged to be respon
estimated speed of the target ship. The pilot
sive to reversals of phase of the voltage em as
then appraises the tactical situation and chooses
by comparing the time phase of the voltage em
the torpedo travel range at which he will torpedo
30
with the time phase of a constant voltage en de
the ship and from what altitude the torpedo will
rived from the source I61 and ampli?ed as by an
be dropped. The respective distances are then
ampli?er I8'5a.
set by means of the potentiometers I15 and Ill.
The phase selector I84 is arranged to control
The pilot also decides upon the speed at which
the polarized relay I 85 to operate the same in one
he will fly the aircraft at the time the torpedo is
direction when on partakes of a plus sign and in 35 released and this speed is set on the potentiom
an opposite direction when the sign of 612 goes
eter I13.
minus. The relay I85 is in turn connected to
If the electrical calculator is in operation dur
control the motor I32 in such manner as to ro
ing the time these settings are being made, the
tate the motor I32 in one direction when sin qs 40 motor I32 will be energized as required by the
exceeds sin [3 and in the other direction when
changes e?ected by changing the‘ potentiometer
sin e exceeds sin qs. The directions of rotation
settings. As soon as the last setting is made, the
of the motor I32 are so chosen that when ener
motor will rotate the notch plate I08 to a posi
gized the motor tends to rotate the stator of the
tion in which the notch plate is displaced from
transformer IllI in such direction as to bring E
its original position by an amount equal to the
sin 5 toward equality with E sin o. Thus the
lead angle o. The pilot may then turn the knob
motor I32 will operate automatically to turn the
92 to a position displaced 180° from that illus
notch plate I88 to a position such that the angle [3
trated in Fig. 6 and then by grasping the pelorus
through which it has been rotated is equal to the
portion of the sight turn the sight in the required
angle ¢ as determined by the electrical calcu 50 direction until the projection III snaps into the
lator. When ,3 and ¢ are equal, 212 becomes zero
notch H8. The sighting line ‘I is thus displaced
and the polarized relay I85 assumes a neutral
from the axis of the aircraft by the lead angle <1:
position de-energizing motor I32.
and the pilot then changes his course to bring
The motor I32 may be of any suitable type
the sighting line ‘I to bear upon the target ship.
capable of having its direction of rotation re
When this is accomplished, the subsequent release
versed by a double-throw relay. A split-series
of the torpedo will result in the torpedo being
?eld commutator motor has been found suitable.
started along the proper course to intersect the
It will thus be seen that the calculating device
target ship at the collision point 0.
just described coacts with the motor I32 so as
If desired. the pilot of the aircraft, instead of
to effect an automatic angular shifting of the 60 turning the sighting device by hand until the
pelorus portion of the sighting device by an
projection III engages the notch IIO, may after
amount equal to the lead angle ¢. The direc
setting the target course arm 9‘! turn the knob
tion of measurement of the angles is so taken that
92 to a position displaced 180° from that illus
the angular displacement of the sighting line ‘I
trated in Fig. 6 to thereby immediately engage the
is opposite to the direction in which the target
projection III with the notch I I8. Thereafter the
operation of the motor I32 resulting from setting
ship TS must be led so that the pilot of the air
up on the control member 9 the various factors
craft, by angularly changing the course of the
involved in the calibration of the angle ¢ will
aircraft in the direction in which it is necessary
result in the sight being turned automatically
to lead the target ship TS, may bring the sight
ing line ‘I to again bear upon the target ship. 70 to the corresponding angular position.
By then holding the sighting line ‘I on the target
Additional aspects of the torpedo course problem
ship, the pilot of the aircraft is permitted to
As was pointed out hereinbefore (column 5
maintain a course along which the torpedo must
supra) the preceding analysis relating to the
travel in order to intercept the target ship at the
75 calculation of the torpedo course was based upon
collision point 8.
em and an is so adjusted that the mixer effects
l
ZiiQ-Q
21
2,412,585
the assumption that the ?ight path of the aircraft
along the line l3 before the veering -l1 and along
the line [8 after the veering de?ned straight lines.
Under ordinary circumstances the real paths I3
and I8 followed by the aircraft are curved due to
the simultaneous progress of the target ship TS
and the aircraft 12 while the aircraft is being so
piloted as to maintain the sighting line dead on
the target ship. These curved paths are of the
type commonly referred to as “homing paths” 10
and are illustrated in Fig. 13 which is a diagram~
22
The sighting device as a gun sight
Reference has-been made hereinbefore to the
alternative use of the device of our invention as
a gun sight for sighting guns which are mounted
on the aircraft in a ?xed position adjusted to ?re
straight ahead of the aircraft. It has been
pointed out that the sight may be adjusted for
this use by latching the pelorus portion of the
sight to the ?xed portion 34 of the sight by turn
ing the control knob 92 to the position illustrated
in Fig. 6 to engage the latch with the upper notch
matic view similar in all respects to Fig. 2 here
plate 11 and by turning the Vertical adjustment
inbefore discussed except for the fact that it il
lustrates the curved shape of the “homing paths.”
handle 13 to a position engaging the eccentric
As a general proposition, however, the aircraft 15 member 10 With the detent arrangement 12, the
adjusting nuts 68 and the horizontal adjustment
velocity V is of the order of four or ?ve times the
velocity U of the target vessel, with the result that
screws 82 and 83, providing, respectively, for ver
the curvature of the “homing paths” is very slight
tical and horizontal bore-sighting adjustments to
so that the slight curvature actually present has
be made.
no signi?cant influence on the geometry entering 20
At this point it is desired to point out that the
into the calculation of the lead angle 4). Such
collimating type of sighting means illustrated
path curvature as does occur, however, has the
herein possesses advantages that cannot be real
effect of slightly increasing the observed approach
ized through use of the ordinary gun’ sighting de
angle 0 before the veering maneuver l1 and of
vices such as the conventional ring and bead
slightly decreasing the observed approach angle 0 25 sight. The principal advantages are that it is
after the veering l1 and during the time the air
not necessary for the user of the sight to main
craft is following the course l8.
tain the eye which he is using to sight the target
Although in most instances the variation of the
in precise alignment with two ?xed sighting
approach angle'o will be imperceptible, our inven
points as is the case with the ordinary ring and
tion permits the pilot to take any perceptible 30 bead sight but instead is permitted considerable
change of this angle into account and permits an
latitude as to the lateral, vertical and fore and
instantaneous adjustment to correct for the' per
aft positions of the eye being used to sight the
ceived change in the approach angle by readjust
target. Further, the collimating type of sight
ing the target course arm 91 anew into visual
causes the reticule cross-hairs to appear to be
alignment with the course of the target. Such a 35 projected on to the target itself so that the in
readjustment of the position of the target course
tersection of the cross-hairs de?ning the line of
9‘! will instantly correspondingly change the cal
sight appears in focus to the pilot the same as
culated value of the angle ¢ and will cause the
does the target itself, whereas with the ordinary
electrical calculator portion of our invention to
ring and bead sight it is impossible to simulta
operate the motor I32 and readjust the angular 40 neously maintain the sighting elements and the
position of the pelorus portion of the sight to
target in focus. Consequently with the ring and
establish the corrected sighting line.
bead sight the actual sighting elements used are
As an alternative procedure the curvature of
seen in a hazy and blurred manner when a sight
the initial approach path l3 can be entirely
is taken on the target, with the result that it is
avoided by making this part of the approaching 45 dimcult to determine whether or not the sight
on a straight air interception course I 3" illus~
is taken as accurately as is desired. This diffi
trated in Fig. 14. The air interception course
culty is completely avoided through the use of
I3" is so chosen that if the aircraft were to con
the collimating type of sight.
~
tinue therealong it would pass directly over the
In the alternative use of the device of our
target vessel at the point indicated in Fig. 14 as 50 invention as a gun sight for guns ?xed on the
TS".
aircraft, it may be desirable to introduce a lead
In this procedure the target does not appear
angle when ?ring at a moving target such as
dead ahead of the aircraft during the initial ap
when stra?ng a surface ship. Such a lead angle
proach but at a constant air interception lead
may, of course, be introduced by proper manipu
angle which may be denoted by the symbol ¢”.
lation of the latch knob 92 and operation of
This angle is de?ned by the law of sines in the air
the
hand crank I30. Our invention, however,
interception triangle as
contemplates using the electrical calculating de
sin ¢"=U/V sin 0
(29)
vice hereinbefore described as a means for auto
matically computing the gunnery lead angle to
Our invention is adapted to the ready execu 60 permit the pilot to introduce the gunnery lead
angle into the sight without resorting to mental
tion of this alternative procedure. All that it is
trigonometrical calculations.
necessary for the pilot to do is during the prelim
If the symbol qs' is used to represent the proper
inary approach phase [3 to swing the pelorus por
lead angle for gunnery, the magnitude of this
tion of the sight (as by engaging the latch with
angle may be expressed by the equation
the notch H0 of the lower notch plate I08 and
turning the crank [30) through the angle ¢" to a
U sin 6
position so selected that upon continued approach
V-i- VM
(30)
no course change of the aircraft is required to
where 0 is the target approach angle, U is the
keep the sighting line on the target vessel. Ex
70 velocity of the target, V is the velocity of the
perience has shown that no great accuracy of this
aircraft and VM is the known average velocity
adjustment is required and that in fact a very
of the projectiles discharged by the ?xed guns.
rough estimate of the air interception lead angle
For the purpose of permitting the pilot to effect
¢" willgenerally su?ice to make the approach
an automatic calculation and setting of the sight
path straight for all practical purposes.
75 to the gunnery lead angle ¢', we employ a switch
2,412,585
23‘
24
I86 (see Fig. 12) which may be arranged as a
single-pole double-throw switch movable from
a normal position adapting the calculating de
vice for torpedoing calculations to a second posi
tion converting the calculating device to the cal
culation of the gunnery lead angle ¢'.
As is shown in Fig, 12, the switch I88 is inter
of the target ship TS instead of colliding with
the ship as is desired. It is accordingly nec
essary that some means be provided for appris
ing the pilot of the aircraft of his arrival at the
chosen release point RP corresponding to his
previously selected torpedo travel range R as
set up on the potentiometer I'I'I.
posed between the output of the ampli?er stage
Referring again to Fig. 2, the length of the
I12 and the potentiometer I13 so that when the
side 2I of the sighting triangle has been repre
switch is thrown to its second position, this cir 10 sent-ed by the symbo1 Y and the apparent length
cuit is opened and a circuit is established be
of the target ship TS as viewed from the release
tween the output of the ampli?er I12 and a po
point RF is represented by the symbol L'. It
tentiometer I81. The potentiometer I81 is pref
will be noted that the distance Y may be ex
- erably housed within the control member 9 and
pressed in terms of the apparent length L’ of
connected to the same dial as that to which the 15 the target ship TS and the angle between two
potentiometer H3 is connected. The potentiom
sighting lines 302 and 303 directed, respectively,
eter I8‘! is calibrated in terms of W, V and VM in
from the release point RP to the bow and stern
such manner that the voltage output of the poten
of the target ship TS. The angle between the
tiometer I81 is
lines 302 and 303 may be expressed in terms of
20 the distance S subtended thereby at an arbitrarily
chosen distance F from the release point RP.
(31)
m = K5(V+ V51)
The distance S may be computed from the follow
ing equation
when the dial 0f the potentiometer I8‘! is set
to indicate the value of V corresponding to the
forward speed of the aircraft.
25
Employing the symbol L to represent the actual
The voltage 613 is applied to an ampli?er stage
length of the target ship TS, the apparent length
I 88, the overall gain of which is made equal to
L’ may be very closely approximated by
K5. Thus the output of the ampli?er I88 is
L'=L sin 0
(32)
30
(35)
Also it may be stated from the law of sines that
R/Y:sin 0/sin a
(36)
The output of the ampli?er I88 is connected as
indicated at I89 to that input channel of the
where a is the angle between the sides R and D
mixer I82 to which the output of the mixer stage
of the sighting triangle. However
I19 is applied. It will be recalled that there is 35
applied to the other input channel of the mixer
I82 a voltage
e11=E sin ,6
Substituting Equations 35, 36 and 37 in Equation
34 gives
(33)
Like the voltages em and en, the voltages an 40
_
and 611 are so phased that the mixer effects a
subtraction of these two. By this the voltage
output of the mixer I82 is made proportional to
the difference between sin ¢' and sin e. As a
result, the phase selector I84'and polarized relay
(38)
The device of our invention includes a mech
anism associated with the reticule 60 for permit
ting a direct comparison between the angle de
?ned by S at a distance F from the release point
RP and the angle de?ned by L’ at a distance Y
I85 are actuated in the manner hereinbefore de
scribed in connection with the use of the device
as a torpedo director to automatically position
the pelorus portion of the sight at the gunnery
lead angle qt’ relative to the axis of the air
craft.
Thus in order for the pilot of the aircraft
from RP.
The device for permitting this direct compari
son comprises a galvanometer including a per
manent magnet 304 secured to a mounting ring
305 which is in turn disposed within the housing
portion 45 of the pelorus portion of the sighting
device (see Fig. 6). The galvanometer move
ment is of substantially conventional construc
tion comprising a coil 306 supported upon a pivot
shaft 301 for pivotal movement between pole
to use the device as a gun sight and to introduce
the gunnery lead angle ¢' into the setting of the
sight, it is only necessary for him to turn the
switch I86 to its second position, set the target
course arm 91 to alignment with the course of
the target, set the potentiometer I10 to corre
spondence with the velocity of the target, and
set the potentiometer I81 to correspondence with
the velocity of the aircraft. Thereafter when the
sighting line is held on the target, the course of
pieces 30B and 309 de?ned by the permanent
magnet 304. The moving coil 305 is normally
urged to one position as by means of a restoring
spring and is so arranged that the passage of cur
rent through the coil will result in a pivotal
the aircraft will be such as to lead the target
by the calculated gunnery lead angle ¢'.
Calculation of range indication
FL sin2 0
_R sin (45-1-0)
The “ranging” mechanism
movement of the coil against the force of the re
65
In using the device as a torpedo director, it is
necessary in order that the released torpedo
may collide with the target ship to release the
torpedo from the aircraft at the time the air
craft reaches a release point RP located in ac
cordance with the chosen torpedo travel range.
If the torpedo is released either sooner or later
than at the point RP. the torpedo will in all
probability pass, respectively, behind or in front 75
storing spring.
.In conventional galvanometer constructions
the moving coil carries a hand or needle adapted
to be moved over a dial to permit a measurement
of the current ?owing through the coil. Accord
ing to our invention the hand or needle is sup
planted by an opaque member 3I0. This mem
ber may be formed of wire or similar small di
ameter rigid stock. It comprises an outer curved
member or horn 3II and an inner curved mem_
her or horn 3I2, these horns being held in a pre
2,412,685..
25.
26
determined spaced relation to each other by end
members 313 and 314, the entire assembly being
the apparent length of the target ship will grad
ually increase and the pilot will be apprised of
the fact that he has arrived at the release point
tending members 315 and 316 and suitably bal
RP by the expansion of the apparent size of‘ the
anced as by means of a conventional counter 5 target ship until it just exactly extends between
weight construction.
the breaks in the horizontal luminous reticule
Reference to Fig. 8 will reveal that the reticule
line 311.
60 comprises an opaque member de?ning a hori
In order for this operation to take place. it is
zontal transparent line 311. This line may be
only necessary that the moving coil 306 be so
formed by actually cutting a thin slot in a piece 10 moved as to position the member 310 as may be
of sheet metal or like material or, alternatively,
required to make the distance between the inter
the reticule 50 may be made of glass, coated with
section of the reticule line 311 with the horns
an opaque substance and the line 311 de?ned
311 and 312 equal to the distance S as calculated
by engraving a line in the opaque substance of
from Equation 38, supra. This result may be
suf?cient depth to completely penetrate the same. 15 obtained by causing a current to flow through the
In any event, the reticule 60 is designed to block
moving coil 306 which is proportional to the
all of the light emanating from the lamp globe
calculated magnitude of the distance S.
54 except that which passes through the line or
The electrical calculation of S
slot 311 and three cross lines or slots 318, 319
and 320.
We
have
also illustrated by means of the block
20
The cross line 319 is located in the center of
diagram (Fig. 12) the manner in which a voltage
the reticule 60 so that the intersection of the
proportional to the distance S may be developed.
lines 311 and 319 de?ne the direction of the
For this we employ as the source of the voltage
sighting line 1. The cross lines 318 and 320 are
the same alternating potential generator 161 as
located equal distances on opposite sides of the 25 is employed in the calculation of ¢ as has been
vertical center line 319 and are employed for the
previously described. It will be recalled that the
connected to the moving coil 306 as by radially ex
purpose of assisting the user of the device in esti
voltage E generated by the source 161 is con
mating distances and the like.
veyed to the rotary transformer 104 so that the
output voltage thereof is
The opaque member 310 previously referred to
'isvdisposed with its plane parallel to the plane
e1=E sin 0
(39)
of the reticule 60 and lies closely adjacent there 3°
to. The curved horns 311 and 312 of the mem
The voltage e1 is applied to the input winding
ber 310 form an inverted bent V and so extend
of the immediately adjacent rotary transformer
across the horizontal reticule line 311. When
103 so that the voltage output thereof will be
the device is used, the reticule appears to de?ne 35
luminous lines corresponding to the lines 31'1—320
e1a=ei sin 0
(40)
and the central line of light corresponding to the
or
reticule line 31'! appears to be broken at the
points where the members 311 and 312 cross the
e1s=E sin2 0
(413
line 311 and cast their shadow thereon.
The horns 3| 1 and 312 are curved as is clearly
40
shown in Fig. 8 and their relative disposition is
such that the point of intersection of each of
the horns 31 1 and 312 with the horizontal reticule
line 311 occurs on opposite sides of the vertical
center line 319 and at equal distances therefrom.
Furthermore, the horns 311 and 312 are so posi
tioned that the distance between the points of
intersection of these horns with the horizontal
reticule line 31 '1 varies in direct proportion to
the angular movement of the moving coil 306 to
which the horns are secured,
If the focal length of the lens 46 be used as
.
The voltage 1915 is fed to a potentiometer 321
comprising one element of the unit 146 of the
control member 9. It will be recalled that the
element 145 included a potentiometer 111 which
was used to introduce the factor R into the
calculation of the lead angle <1>. The potentiometer 321 just referred to in connection with the
calculation of the distance S preferably com
prises a second potentiometer included in the unit
146 and connected to the same dial as is used to
operate the potentiometer 11‘! so that when the
dial is set to the selected range, both of the
potentiometers Ill and 321 are set to the cor
the distance F, the distance between the point of
responding positions.
intersection of the horns 311 and 312 with the 55 This dial of the potentiometer 321 is calibrated
horizontal reticule line 311 may be made equal
in terms of R, the selected torpedo travel range
to the distance S, and the angle intercepted by
and the calibration is so arranged that the
the breaks in the horizontal luminous reticule
voltage output of the potentiometer is
line 311 will then be equal to the angle formed by
the apparent length L’ of the target ship TS when 60
located at the distance Y. Thus, if the moving
The voltage cm is fed to an ampli?er stage 322,
coil 306 is turned to an angular position such
the overall gain of which may be adjusted to be
that the distance between the breaks in the
equal to Ks so that the voltage output of the
luminous reticule line 311 is equal to the dis
ampli?er 322 will be
tance S, the pilot may, by comparing the appar
en=E sin2 0/R
ent length of the target ship as viewed through 65
(43)
the sighting device with the apparent distance
The voltage en is applied to a potentiometer
between the breaks in the luminous line appar
323 comprising the unit 145 of the control mem
ently superimposed upon the target ship and the
ber 9. The dial of this potentiometer is cali
immediately surrounding area, determine wheth
er or not the aircraft has reached the release 70 brated in terms of L, the actual length of the
target ship TS and this calibration is so ar
point RP.
As the aircraft proceeds on its course toward
the release point RP generally approaching the
target ship and gradually drawing closer thereto, 75
ranged that the voltage output of the potentiom
eter 323 is
2,412,585
27
28
The voltage are is fed to an ampli?er stage 324,
the overall gain of which is adjusted to be equal
to FKi. Thus the voltage output of the ampli?er
324 is
portional voltage is applied as indicated at 329
in Fig. 12 to the moving coil 306 of the galvanom
ei9=(E'FL sin2 0) /R
eter so as to move the member 3I0 to a position
(45)
The voltage 619 is fed as indicated at 325 to a
normally high gain ampli?er 326, the nominal
gain of which may be referred to as u.
The output voltage e20 of the ampli?er stage 10
326 is applied by means of a feedback circuit
32'I—328 to the input of the ampli?er 3126. The
feedback is arranged to be negative; that is, out
_
of phase with the input voltage e19 so as to, in
effect, reduce the gain of the ampli?er stage 326. 15
Within the feedback circuit 321-328 we in
clude the rotary transformer I02 which, as will
be explained more fully hereinafter, is so ar
ranged in the sighting device and so coordinat
ed with the rotary transformers I 0| and I03 as to 20
have a transformation ratio proportional to
the sine of the sum of the angles 5 and 0. The
ampli?er stage 326 together with the feedback
such that the horns 3H and 3I2 thereof inter
cept a distance along the reticule line 3|‘! equal
to the distance S.
Preferably the circuit constants are so chosen
as to produce a maximum movement of the light
intercepting member 3I0 by a change in the
value of (5+0) from :90" to :45” or i135”.
With the parts so adjusted, it will be apparent
that unless provision is made for preventing the
occurrence, an excessive voltage will be applied
to the coil 306 whenever the target course arm
91 and the pelorus portion are so positioned with
respect to each other as to provide a value of
(3+0) less than :45" or greater than i-l35°.
This occurrence is prevented by employing a
gain limiting circuit which includes a recti?er
392, the input of which is coupled as at 393 to
the output of the ampli?er stage 326, and the
output of which is connected as at 394 to control
the gain of the ampli?er stage 326 in such man
circuit 32'I—328 constitutes a negative feedback
ner as to produce a reduction in gain as a result
ampli?er.
of an increase in the output potential of the rec
In such an ampli?er the overall gain _
of the system may be expressed by
G==u/ (1+uk)
ti?er 392.
The recti?er 392 is preferably so biased as to
(46)
,
prevent any rectifying action from taking place
until the alternating potential applied to the
where u is equal to the nominal gain of‘ the am
pli?er stage and k is equal to the feedback con 30 input thereof rises to a value equal to the voltage
corresponding to maximum de?ection of the gal
stant or ratio between the input to the feedback
vanometer.
circuit and the output of the feedback circuit.
When the output voltage of the ampli?er stage
For a high gain stage Where u is very large with
326 rises to a value exceeding that corresponding
respect to one, Equation 46, supra, may; be writ
to maximum de?ection of the galvanometer, the
ten as
recti?er 392 will begin to rectify and the result
G=1/lt
(47)
ing direct potential is so applied to the ampli?er
stage 326 as to reduce the gain thereof and pro
Likewise if e1 represents the input voltage to the
duce a corresponding reduction in voltage gen
feedback ampli?er and co represents the output
erated thereby. The recti?er 392 thus operates
voltage of the feedback ampli?er, it may be said
to prevent any appreciable rise in the voltage
that
applied to the galvanometer coil 305 above that
e0=€iG
(48)
corresponding to a value of (0+0) equalling
:45“ or i135° and thus serves to prevent injury
Comparing Equations 47 and 48, we ?nd that
to the moving coil 306 of the galvanometer.
eo=ei/k
(49)
Reference has been had hereinbefore to the
fact that the rotary transformer I02 is so co
Applying these general considerations to the
feedback stage involving the ampli?er 326 and
the rotary transformer I02, it will be observed
ordinated with respect to the rotary transformers
that the function 'sin (0+0) is the feedback con- I
stant and corresponds to k of Equation 49 while
the input voltage e19 corresponds to c1 and the
output voltage e20 corresponds to 60. It may thus
be seen that
e2o=e19/Sin (6+0)
(50)
IM and I03 as to cause the transformation ratio
to be proportional to the sine of the sum of the
angles p and 0. The manner in which this result
is achieved is illustrated diagrammatically in Fig.
11. In this diagram the numeral M is used to
represent the axis of rotation of the rotary trans
formers IOI—I04. The arrows bearing the refer
ence characters IOIR, I02R, I03R and I04R are
used to, respectively, designate the rotors of the
rotary transformers I 0 I—I 04.
01‘
_ EFL sin2 0
(51’
It will be noted that when ,8 equals ¢i as is the
case when the motor I32 has operated to move
the sighting device through the angle 18 corre
sponding to the calculated lead angle o, Equa
tion 51 becomes identical with
EFL sin? 0
Comparing Equation 52 with Equation 38,
supra, will show that
Thus the output voltage can is directly propor
tional to the calculated value of S. This pro
In a similar manner the reference characters
60 IOIS, I028, I038 and IMS are used to designate
the stators of the respective rotary transformers
I0 I—I04. It will be recalled that the stators I036
and W453 are ?xed as by means of the screws
I05a to the pelorus portion of the sight, this
securing of the stators I03S and N48 being indi
cated at 330 and 33I, respectively, in Fig. 11.
It will likewise be recalled that the rotor IOIR
of the transformer IOI is likewise ?xed to the
pelorus portion of the sighting device by means
of the split plug II4. This ?xing of the rotor
I MB is indicated at 332 in Fig. 11. The stators
IOIS and |02S of the rotary transformers MI
and I 02 are secured to each other and to the
lower notch plate I08 so that when the notch
75 plate I08 is latched to the ?xed portion 34, the
2,412,585‘
29
30
angle between the rotor IOIR and stator IIHS
will be equal to ,3, this ?xing of the stators IOIS
and I02S being indicated by the dashed line 333
correspondingly increase. When the apparent
length of the target ship has increased to a point
where it appears to exactly ?ll the gap between
the two breaks in the horizontal reticule line, the
pilot of the aircraft is thereby apprised of the
fact that he has reached the proper release point
RP and thereupon promptly launches the torpedo.
in Fig. 11.
‘
Similarly, the rotors IIIZR, I03R and IMR, are
each secured to each other and to the target
course arm 91 as by connecting the shaft 99 to
each of these rotors. This interconnection of the
Operation
rotors I02R,—I04R is indicated in Fig. 11 by the
At this point it is desired to point out a differ
dashed line 334.
10
ent possible mode of operation of the device of
In Fig. 11 we have illustrated the target course
our invention which may be used to advantage
when the factors U and L are known before the
target ship is sighted as by reason of previous
tors H138 and IMS are ?xed to the pelorus por
tion, this results in disposing the rotors IDZR, 15 ?ights over the target area or by reason of in
formation relayed to the pilot of the aircraft by
I03R and IMF. at an angle a relative to the sta
tors. This angular relationship is diagrammati
radio. Under such circumstances the pilot may
cally illustrated in Fig. 11.
decide or be instructed as to the range at which
the torpedoing operation will be performed, the
Similarly, in Fig. 11 we have illustrated the
pelorus portion and the sighting line ‘I de?ned 20 height from which the torpedo will be released
thereby as having been swung through an angle
and the forward speed of the aircraft at the time
the torpedo is launched. Under these circum~
)6. Since the rotor IOIR is movable with the
stances the pilot may set up each of the factors
pelorus portion and the stators IOIS and MRS
are ?xed to the notch plate I08, this swinging of
H, V, U, L and R on the control member 9 before
the target ship is sighted.
the pelorus results in angularly shifting the sta
arm 9'! as having been revolved through an angle
0 relative to the sighting line ‘I. Since the sta
tors IOIS and H328 through the angle ,3 relative
to the rotor IOIR.
The pilot may then proceed until the target
ship is sighted. With the pelorus positioned to
take a sight on the target ship TS, the target
Referring particularly to that portion of Fig. 11
illustrating the rotor and stator of the trans
course arm 91 is set to parallelism with the course
former I02, it will be noted that the stator I02S 30 of the target ship TS and the control knob 92 is
then manipulated to drivably engage the pelorus
has been shifted in one direction by the angle 18,
whereas the rotor has been shifted in the oppo
portion of the sighting device with the electric
site direction through the angle 0. As a result
the angular relation between the rotor IMF. and
the stator I02S comprises the sum of the angles
5 and 0. Thus the transformation ratio of the
transformer I02 is made directly proportional to
the sine of the sum of the angles 5 and 0.
The operation of the sighting device with the
hereinbefore described “ranging” feature is not
materially different from that which has‘ already
been described in connection with the operation
motor I32. This completes the operations which
the pilot must perform in order to place the sight
in readiness for use. Thereafter it} is only neces
sary for him to so change the course of his air
craft as to bring the sighting line ‘I to again
bear upon the target ship and then follow that
course until the target ship appears to ?ll the
gap between the breaks in the horizontal reticule
of the calculator which determines the angle ¢
and shifts the sighting device to the correspond
line. When this condition obtains, the torpedo
is released and will, barring a subsequent change
in course by the target ship, collide with the
target ship at the collision point 0.
ing position. At the time the pilot of the air
craft is operating the control member 9 by set
ticularly adapted to permit the pilot of the air
ting up on the various dials thereof the values
of the factors H, V, U and R, he will at the
same time set on the corresponding dial the value
of L corresponding to the actual length of the 50
target ship TS.
This factor, like the factor U,
is known to the pilot of the aircraft as soon as
The sighting device of our invention is par
craft to change his mind about any of the under
lying factors involved at any time during the ap
proach to the target. He may, for example, de
cide upon arriving at closer range that the vessel
is of different length or moving at a different
speed than assumed previously or he may venture
he identi?es the nationality and type of the tar
a better estimate of the target’s course or he may
get ship TS. When this operation is completed,
decide to ?y slower or faster, higher-or lower or
to launch the torpedo from a closer range than
had been his earlier strategy. All he has to do
is to correctly readjust the dial members I52 of
the control units I42--I46 or the position of the
target course arm 91. The electrical calculating
mechanisms hereinbefore described will immedi
ately effect the proper correction of the. azimuth
'angle 5 of the notch plate I08 and the proper
correction of the position of the galvanometer
horns 3| I and »3I2 to conform to the newly deter
the mechanism operates in the manner herein
before described to direct the sighting line in
such manner that the launched torpedo will fol
low a course making the lead angle ¢ with the
sighting line,
At the same time the calculator just described
actuates the galvanometer so that the reticule
pattern observed by looking through the sighting .
device is characterized by having two breaks in
the horizontal luminous line. The pilot of the
aircraft continues along the torpedo course by
so guiding the aircraft as to keep the intersecting
center lines of the reticule pattern on the target
ship. When the aircraft is at a point disposed
farther from the target ship TS than the proper
release point RP. the apparent length of the tar
get ship as viewed in the sighting device will be
less-than the distance between the breaks in the
horizontal reticule line. As the‘ distance between
the aircraft and the target ship is gradually re
duced, the apparent size of the target ship will
mined conditions.
From the foregoing it will be observed that we
have provided a sighting device which includes
the necessary mechanism for taking into account
each of the various factors which go to deter
mine the location of the proper torpedo or pro
J'ectile course which will be required in order to
produce the desired collision between the projec
tile and the target.
Furthermore, the device of our invention oper
ates to automatically perform the necessary trig
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