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Патент USA US2406836

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Sept. .3, 1946.
w. H. T. HOLDEN
2,406,836
ELECTRIC AIR POSITION INDICATOR
Filed March 24, 1944
4 Sheets-Sheet 1
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JW@
ATTORNEY _
Sept 3» 1946-
w. H. 'r. HOLDEN
2,406,836
ELECTRIC AIR POSITION INDICATOR
, Filed March 24, 1944
4 Sheets-Sheet 2
/Nl/ENTOR
W H 7.' HOLDEN
www
BV
.
6?-6. M
Arrows/Ey
Selma 3, 1946.
w. H. T. HQLDEN
2,406,836
ELECTRIC AIR POSITION INDICATOR
Filed Marçh 24. 1944
4 Sheets-Sheet 3
/
- WHT/HOLDEN
BV
.
f? ¿î M
ATTORNEY
Sept. 3, 1946.
w. H. T. HOLDEN
2,406,836
ELECTRIC AIR POSITION INDICÁTOR
Filed March 24, 1944.
4 Sheets-Sheet 4
/Nl/ENTOR
I4.’ H. I HOLDEN
@6. ¿ma
ATTORNEY
Patented Sept. 3, 1946
2,405,836
UNITED STATES
ATENT OFFICE
2,406,836
ELECTRIC AIR POSITION INDICATOR
William H. T. Holden, Woodside, N. Y., assignorV
to Bell Telephone Laboratories, Incorporated,
. New York, N. Y., a corporation of New York
Application March 24, 1944, Serial No. 527,998 I
5 Claims.
1
This invention relates to an air position indi
(Cl. 235-61)
2
sufiiciently compact and of light enough weight
cator for use on an aircraft for enabling the
that it may be readily installed in small air
pilot or the navigator to determine at any in
planes.
stant the latitude and longitude of his position
To attain these objects apparatus has been de
and the air miles which he has flown from any 5 signed in two parts, an indicator unit and a con
speciiied take-oit point. More particularly the
trol unit. Most modern airplanes are equipped
invention is concerned with the provision of elec
with an air mileage unit and with either a re
trical equipment for controlling indicators which
continuously indicate the aircraft position in de
mote control ,earth inductor compass or
re
mote control magnetic compass unit. From these
grees and minutes of latitude and longitude and 10 units information may be secured concerning the
the air miles which have been flown.
air speed and the compass course of the airplane
The utility of apparatus of this character is
flight for enabling a control unit to control the
quite evident. On ships the problem of deter
indicator unit. The indicator unit is provided
mining the ship’s position at any instant is not
with three indicators `which may be of the count»
great due to the slow speed at which surface
ing wheel type, one of which is controlled to in~
ships sail and due to the fact that such ships
dicate the air miles flown, the second of which
always carry a navigator as a member of the
indicates the degrees and minutes of latitude of
crew who has ample time to make celestial ob
the instant position of the airplane, and the third
servations, to do the navigational plotting that is
of which indicates the degrees and minutes of
necessitated from the data secured from such „ longitude cf >the instant position of the airplane.
observations and to keep the necessary records of
The indicator may also be provided with a pointer
course and speed to enable a dead reckoning po
and compass rose for indicating the true com
sition `to be always known. However, aircraft and
pass
course of the flight. Provision is made for
particularly airplanes which have high cruising
enabling the latitude and longitude indicators to
speeds present a_more difficult problem for solv
ing navigational data to determine positions.
This is particularly true of airplanes of the high
' be reset to indicate the latitude and longitude of
the positions of the airplane at some known point
as, for example, at the take-oiî of a flight and
with means for enabling these indicators to be
30 operated in one or the other direction dependent
upon whether the flight is being conducted in,
tions, evasive action involves such frequent
the north or south hemisphere or east or west oi
changes of course and speed that a navigator
a particular meridian.
cannot keep an accurate log from which the dead
As disclosed in one modification of the inven
reckoning position may be obtained. The appa
ratus which is the subject of this invention may . tion the motor-generator sets and gearing for
driving the several indicators are enclosed in a
be described as an automatic dead reckoning de
speed type which may not have space to accom
modate a navigator as a part of the crew. Fur
thermore in aerial navigation under war condi
casing which houses the indicators. Since this
assemblage, while relatively compact, does not
Apparatus has heretofore been proposed for
readily permit of its mounting in the usual in
producing indications of the position of an air
plane and the air miles flown which may be ob 40 strument panel installed in front of the pilot, a
served by the pilot but such apparatus has been
simplified form of indicator unit the indicators
of which may be operated by remote controls
of a complicated mechanical construction, mak
vice.
` ing its production slow and costly, and requiring
from motor-generator sets located in the con
extremely close limits of mechanical dimensions
trol unit may be used and is disclosed in the modi
to produce an acceptable accuracy of results.
45 ñed form of the invention. This indicator unit is
It is therefore an object of the present inven
suñîciently compact so that it may be mounted
tion to provide apparatus electrically controlled
in accordance with the air speed of an aircraft
and with the true course of the flight to con
in the instrument panel and occupy no greater
area in such panel than do the other iiight in
struments such as the altimeter or remote in
tinuously indicate the latitude and longitude of 50 dicating compass.
the air position of the aircraft and the air miles
The control unit comprises the amplifier' and
which have been flown whereby substantially
relay apparatus necessary to control the motor
accurate indications are made possible.
and generator assemblies of the indicator unit,
It is a further object of the invention to pro
when installed therein or when installed in the
vide air position indicating equipment which is 55 control unit, in response to the operation of the
afioaeec
a
counting wheel type the wheels of which may be
viewed through a sight opening in the face of
the housing. One of these counters AMC indi
air speed motor unit and the compass unit of the
airplane.
For a clearer understanding ofthe invention
cates the air miles or total distance ñown relative
to the air. A second one of the counters LC in
and the mode of its operation reference may be
had to the following detailed description there
«en
cf when read in connection with the accompany
ing drawings in which:
Fig. 1 shows schematically the assembly of the
apparatus units involved in the present inven
dicates the latitude and a third of the counters
LOC4 indicates the longitude relative to the air
(neglecting wind) oi the flight position of the
airplane after these counters have been set at the
10 latitude and longitude of some known point, for
tion;
example the take-off point of the iiight.
Fig. 2 is a circuit diagram showing schematical
The circuit diagram of Fig. 2 shows schemati
cally the manner in which apparatus embodying
the modiiication _of the invention disclosed in
Figs. 4 and 5 or apparatus embodying the modi
iication of the invention disclosed in Figs. 5 and 6
is interconnected electrically. In this diagram
the air mileage unit I is disclosed as mechanically
or otherwise coupled to the master generator MG
ly the assembly of the apparatus units;
Fig. 3 is a vector diagram explanatory of the
theoretical aspects of the invention;
_
Fig. 4 showsW the apparatus and circuits of the
indicator unit constituting` one modification of
the invention;
Fig. 5 shows the apparatus and circuits of the
control unit which may be used with either modi
dcation of the invention; and
Y
20
Fig. 6 shows the apparatus and circuits of an
indicator unit constituting a modification of the
invention and control equipment therefor which
andeither mechanically or electrically coupled
as desired with the air miles counter AMC. Y.if
` the rotational velocity of the input to the mas
ter generator is assumed tovbe wo then this rota
tional velocity may be expressed in terms of air
may be assembled as a part of the control unit
speed as KoVt. The master generator has an out
disclosed in Fig. 5.
put potential En which at the angular speed wo
Referring ñrst to Fig. l the several apparatus
may be expressed as Kiwa. This output potential ’
units required to carry forward the invention are
is impressed upon the input of the resolving unit
schematically illustrated. The air mileage unit
MR2 which is oriented by the compass servo CS
which constitutes a part of the apparatus of an
airplane is shown at l. This unit is equipped 30 through the true course angle GN whereupon out
put potentials El and Ee are derived, the potential
with a tachometer generator which is connected
E1 having a value equal t_o_ Eq cos CN and potential
by the cable 2 through the junctionbox 3 and
E2 having a Value equal to lilo sin CN.
cable ll to a tachometer motor which forms part
The potential E1 is applied to the input of the
of the motor-generator set of the indicator 5 for
speed control device AMPI whose output controls
the latitude motor LM to drive the latitude feed
back generator FGI at an angular speed w1 corre
sponding' to the angular speed _wo as modified by
the resolving unit MR2. rl‘he shaft of the motor
LM may drive the latitude indicator LC either
mechanically or electrically as desired. 'I‘he
feedback generator FGI generates a potential E’i
which is equal‘to Kiwi which‘potential is applied
as a íeedback potential upon the input of the
driving the air rmiles indicator, or, alternatively,
rfrom the junction box 3 through the cable 6 to
the control unit 'i if this motor-generator set
constitutes a part of the control unit as illus
trated in the modified form of the invention dis
closed in Fig. 6. If the airplane is equipped with
a remote control earth inductor compass control
unitß or so-called “flux gate” compass unit, such
unit is connected by the cable 9 attached to the
cable Ie, through the junction box 3 to the unit
speed control device AMPI.
‘
5 over cable t. If the airplane is equipped
The potential E2 is applied to the input of the
with a remote indicating compass of the so-called
speed control device AMP2 whose output con
“magnesyn” control type such as is indicated
trols the longitude motor LOM to drivethe longi
schematically at il', this compass is associated
tude feedback generator FGE at an angular speed
with the auxiliary control unit I2 over cable I3
which latter unit is then connected by cable I4 50 402. The rotor shaft ofy motor LOM may drive the
longitude indicator LOC either mechanically or
attached to cable it, through junctionbox 3 to
electrically as desired. The feedback generator
the control unit ‘l and to the indicator unit 5.
FGE.’ generates a potential E’z equal to Kw2 which
If an indicator unit of the type disclosed in Fig.
is impressed upon the input of the resolving unit
6 is used then the compass control unit 8 would
be connected with a remote control indicating 55 MRI which is oriented from the input shaft of
the latitude counter LC either mechanically or
compass on the instrument panel of the airplane.
electrically as desired through the latitude angle
Power for operating the electrical equipment of
the air position indicator is obtained over cable
I5 extending from the Zß-volt .direct current
A whereupon an output potential having a value
E'z cos l is derived and impressed as a feedback
source and the 40G-cycle 26S-volt alternating cur 60 potential upon the input >,circuit of the speed
l control device AMP?.
rent supply source of the airplane.
For a more detailed disclosure of the invention
The air speed motor unit I is driven by an air
reference will iirst be. made to Figs. 4 and-5 which
motor which is responsive to the difference of
pressure between the pilot and the static tubes of
the airplane and in turn drives a tachometer gen
erator which, being driven at a speed commen
65
disclose Vone embodiment thereof.
As previously stated the air mileage unit I,
whose motor. speed is 24; revolutions per minute
per knot of true air speed and whose'maximum
surate with the air speed, generates a potential
speed corresponding .to été()v knots would be 10,800
which varies linearly with the air speed and
revolutions per minute. is geared down by-a re
which potential is utilized to drive a tachometer
motor forming a part of the motor-generator set 70 duction gearing having a ratio of 6 to l to drive
a tachometer generator at a speed'oi 1800 revo
associated with the air miles indicator AMC.
lutions per minute whereby the tachometer motor
The indicator 5 if of the type disclosed in Fig. 4
TM, electrically associated with the air mileage
comprises a housing containing three motor-gen
erator sets each coupled by a suitable gear train
to an indicator which maybe oi the multiple
unit I over the cable 2', is also driven at a speed
of 1800 revolutions per minute.
In the indicator
2,406,836
' É the motor TM through the gearing 400 having',
6
the- shaft '418 of` counter _LC should make one
a speed-up ratio of ’1 to 4 drives the master gen-y
erator MG at four times the speed of the motor
TM or, for example, at 7200 revolutions per min
ute when the motor TM is operating at a speed of Cl
minute or 57,600 to l. This is secured by the
1800 revolutions per minute'.
reduction gear box 4I3 which has a reduction
-
`
revolution for each sixty minutes of latitude.
Therefore the gearV reduction required is 7200
revolutions per minute to .125 revolution per
The master generator MG is a two-phase, 400
cycle induction motor functioning as an induc
ratio of 3600 to 1 followed by the gears 4I6 and
4I'I which introduce a further reduction ratio of
tion generator. A potential Whose amplitude is
16 to l. The input wheel of counter LC, gradu
proportional to the rotational speed and whose 10 ated 0 to 59 minutes, moves continuously mak
phase is substantially constant up to a speed of
ing one revolution for each degree j> latitude.
6000 revolutions per minute appears across the
The other wheels are advanced by decimal
control phase `40| of this generator. This po
Geneva movements in the usual manner to
tentia1 has the same frequency as the 400-cycie,
register the units and tens of the degrees of
26-volt supply AC of alternating current which 15 latitude.
.
Vis connected to its ñxed phase winding 402. The
The shaft 4I8 of the counter is also con
generator may be considered as a transformer
nected t0 the input shaft of the reduction gear
whose ratio is dependent on the rotational speed.
box M9 the output shaft 420 of which is con
The motor TM, through the gearing 400, the
nected to the rotor RI of the magnetic resolver
'reduction gear box 403 ‘having a reduction ratio 20 MRI. The gear box 450 has a reduction gear
of 3600 to 1, and `through the further gearing 404
ratio of 360 to 1 so that a complete revolution
having a reduction ratio of 24 to 9 drives the air
of the rotor RI would result should the counter
miles counter AMC. The input wheel of this
shaft 4I8 rotate 360 revolutions to cause the
counter,` graduated 0 `to 9, moves continuously
counter LC to indicate 360 degrees. The lati
making one revolution for each ten nautical
tude counter LC, however, reads only from 00 de
miles. The other wheels are advanced by deci
grees 00 minutes to 99 degrees 59 minutes and
mal Geneva movements in the usual manner to
readings beyond 75 degrees 30 minutes north or
register the tens, hundreds, thousands and ten
75 degrees 30 minutes south are not used. There
thousands of miles. Since 7200 revolutions per
fore the limit switch LS is provided, which is
minute ofthe shaft of generator MG corre
operated by cam 42| mounted on shaft 420, to
sponds to 450 knots or 7.5 nautical miles per
open the circuit of motor LM and to close the
minute, the input shaft should rotate at 0.75
' circuit of alarm lamp ALM in the event the rotor
revolution per minute and the total reduction
RI should be rotated more than 75 degrees 30
gear ratio between the generator shaft and the
minutes either side of the position in which the
counter should be 9600 to!` 1. This is accom
counter LC indicates 00 degrees 00 minutes.
plished by the gear box 403 and the gears 404.
When a night is being conducted in the
The latitude counter LC is driven by a second
northern hemisphere the driving gear 4I6 is
motor-generator set comprising a. miniature di
meshed with the gear 4I? as disclosed and the
rect current motor LM of the magneto type, the
counter LC will increase its reading as the flight
rotor cf which is directly coupled with the rotor - proceeds northward and will decrease its read
of the feedback generator FGI. This feedback
ing if the flight proceeds southward towards the
generator is a two-phase 40G-cycle induction
equator. When the equator is crossed a reading
motor functioning as a generator and has one
of 00 degrees 00 minutes would be followed by a
of its phase windings 405 connected in series
reading of 99 degrees 59 minutes as the flight
with the phase Winding 40| of the master gen
proceeds into the southern hemisphere. In order,
erator MG and its other phase winding 400 con
therefore, that the counter may increase its read
nected overY conductors V40'! and 408 ywith the
ing through 00 degrees 01 minute, etc., means
winding of potentiometer P3 associated with the
is provided whereby the navigator or pilot may
`input side of the amplifier circuit AMPI of Fig.
reverse the rotation of the counter as the flight
5. The feed back generator FGI is identical with 50 crosses the equator.- This means comprises a
the master generator MG and serves to hold the
pair of connected gears 422 and 423 of the same
speed of motor LM, the armature vcircuit of which
pitch diameter as the driving gear 4I0, mounted
is connected over conductors 409 and 4I0 with
on an idler shaft and so positioned that the gear
the output side of amplifier circuit AMIPl, to a
422 is normally in mesh with gear 4I'I and that
value such that the output of the feedback gen 55 the gear 423 may be meshed with gear 4I0. To
erator ‘FGI , is equal to the output of the master
reverse the direction of rotation of the counter
generator as modified by the magnetic resolver
shaft 4I8 the driving gear 4I6 is moved along
MR2. A flywheel 4II is mounted on the rotor
the driving shaft 4I5 by the control knob 42'4 out
shaft of motor LM Vbetween the rotor of the mo
of mesh with gear 4I? and into mesh with the
tor and the rotor of the generator FGI to delay 60 reversing gear 423. At the same time a shutter
speed changes.
NS (see Fig. l) in the face of the indicator unit
The rotor shaft of motor LM is also connected
5 changes from N to S. In place of the reversthrough a ñexible coupling 4 I 2 to the input shaft
ing gears a switch could be employed for con
of the reduction gear box M3, the iiexible cou
trolling the electrical reversal of the motor LM.
pling reducing the rotational shock to the re
The control knob 424 has three positions, the
duction gear box. The output shaft of the gear
right position being for northward flight, the
box 4I3 is connected through bevel gears 4I4
left position being for southward iiight and the
having a unity ratio, with a shaft 4 I 5 upon which
intermediate position being such that the driving
the pinion 4I0 is slidable. This pinion in the
gear 450 is entirely out of mesh with either the
position disclosed meshes with gear 4I‘I which is
gear 4I? or the reversing gear 423. In this po
mounted on the driving shaft BIB of the latitude
sition the reset gear 425 may be meshed with
counter LC. When the master generator MG is
gear 4I‘I by the operation of the reset knob 426
rotating at a‘speed of 7200 revolutions per minute
to permit the setting of .the counter LC as at a
or 450 knots on„a true course north -correspond-.
dennite fix or landmark the latitude of which is
ing to 7.5 minutes of latitude per minute of time,
known.
'
‘
2,406,836:
7
motor-generator set comprising a miniature di
rect current motor LoM of the magneto type, the
rotor of which is directly coupled with the r'otor
of the feedback generator FGZ.
8
and 443 and the knob 444. It is~ assumed that
the. right ’positionof knob 444 is `dis-closed as
that in which driving gear 436 is in mesh with
The longitude counter LOC is driven by a third
Ul
gear 431 for driving the counter for a flight in the
easternhemisphereì that'the'mid-position of the
phase windings 421 connected in series with the
phase winding 43I of the master generator MG
and its other phase winding 428 connected in
knob is the position vin'which gear '436 is out of
mesh with both gears '431 and 443 and in which
position the reset knob '446 may be operated to
mesh gear 445 with gear 431 to permit the set
ting- of the counter LOC as at a definite iiX or
series with the winding of rotor RI of the mag
netic resolver MRI. The feedback generator FGZ
that the >left position ‘of :knob 444 is .that in which
generatorïis a two-phase 40G-cycle induction ino
tor functioning as a generator and has one rof its
landmark the longitude of which is known, and
driving gear 436 is in mesh with reversing gear
443 for driving the counter in theV direction for
a night in the western hemisphere. A shutter
EW located .in the face of the indicator unit 5
(sce Fig. l.) changes from E to W when the knob
444 is moved to the left. In place of the revers
ing 'gears' a switch could be employed for control
equal to the output of thev master generator
as modified by the magnetic resolver MRI. A 20 ling the electrical reversal ofthe motor LOM.
Also located in the indicator unit 5 is a syn
fiywheel 43I is mounted on the rotor shaft of
ahrc-receiver SR having a Y-type stator the
motor LOM between the rotorrof the motor and
three windings of l.which are connected over con
the rotor of the generator FG2 to delay speed
ductors 441, -448 and 449 with the similar wind
changes.
ings of the stator of a synchro-transmitter (not
The rotor shaft of motor LUM is also connected
shown) but driven by the remote 'control earth
through a flexible coupling 432 to the input shaft
inductor compass unit 8. The rotor R3 of the
of the reduction gear bo'x 433, the flexible cou
synchro-receiver is mounted on the shaft 439
pling reducing the rotational shock to the reduc
which moves the compass needle of the compass
tion gear box. The output shaft of the gear box
is connected through bevel gears 434 having a 30 C and which also moves the rotor R2 of the mag
netic resolver MR2. The winding of the rotor
unity ratio with a shaft 435 'ur-'on' which the
R3 is conneoted over conductors 449 and 450 with
pinion 433 is slid'able. This pinion in the posi
the rotor winding of the synchro-transmitter
tion disclosed meshes with gear 43'! which is
driven by the unit 8 and with the Source AC of
mounted on the driving shaft 43E of the longi
is identical with the master generatorr MG and
serves to hold the speed of motor LoM, the ar
mature circuit of which is connected over oon
ductors 429 and 430 with the output side of am
pliñer circuit AMP‘Z of Fig». 5, to a value 'such f
that the output of the feedback generator is
tude counter LQC. When the master generator
MG is rotating at a speed of ’1290 revolutions per
minute or 450 knots on a true course correspond
ing to '7.5 minutes of longitude per minute of
time, the shaft 433 of counter LoCshould re
volve four times as fast as the shaft 4I8 of the
latitude counter LC since the rate of change of
longitude may be four times vas great as the
rate or change of latitude. Therefore the gear
reduction required is ’1200 revolutions per minute
to .599 revolution per minute or 14,400. This is
secured by the reduction gear boX 433 which has
a reduction ratio of 3600 to l followed by the
400 cycles alternating current.
If the airplane is equìpped'with a remote' cori
trol magnetic compass òf the sci-'called “mag
nesyn” type as disclosed at II in Fig. 1 driven
from the auxiliary compass control unit I2è then
the synchro-receiver SR would also be of the
“magne'syn” type. ’
Í
The horizontal stator winding 443 of the mag
netic resolver MR2 is cor'inectedI in series with
the winding of> potentiometer P2 over conduc
tors 45I and 452 and the vertical stator winding
44| is connected in series with the winding of
potentiometer Pl over conductors 454 and 453.
The Winding' of rotor R2 of this magnetic resolver
is connected in series with» the winding 451| of the
«motion> ratio of 4 to L vThe input wheel of
colui-ter LOC., graduated (l to 59 minutes, moves 50 master generator MG so that a potential Eo‘ is
applied across the winding of the' rotor which
continuously making one revolution for each de
varies with the air speed of the flight and, since
gree of longitude. The other wheels are ad
the rotor winding is oriented in accordance with
vanced by decimal Geneva movements in the
the true compass bearing angle CN of the flight,
usual manner to register the units, tens and hun
a potential is> derived from the horizontal wind
dreds of the degrees of longitude.
ing 440 of this resolver which has a value En
When a flight is being conducted in the east
sin CN anda potential is derived from the ver
ern hemisphere the driving gear 43S is meshed
gears ¿ist and 431 which introduce a further re
with the gear 431 as disclosed and the counter
LoC Will increase its reading as the ñight pro
tical winding 44| which has a value Eo cos CN.
The magnetic resolver MRI previously-referred
ceeds eastward and will decrease its reading if 60 to, the rotor RI of which is driven 'from the shaft
4 I ß of the latitude counter LC, has its rotor wind
the flight proceeds _westwardly~ This counter may
ing energized by potential impressed thereon
read 000 degreesv 00 minutes to 999 degrees 59
minutes but the maximum useful range is, of
course, 060 degrees 00 minutes toA 180 degrees (l0
from the stator winding 428 of the 'feedback
the flight proceeds into the Western hemisphere.
former is bridged across the winding of poten
In order therefore that the counter may increase
tiometer P4.
generator FGZ and has two windings of its Y
minutes east or west. When the reference me 65 connected stator connected by conductors 454
and 455 with the primary winding' of trans
ridian is crossed a reading 000 degrees 00 minutes
formcr TI, the> secondary winding of which trans
would be followed by 999 degrees 59 minutes as
its reading through 00o degrees ol minute, etc., 70
means is provided whereby the navigator or pilotV
may reverse the rotation of the counter as the
flight crosses the reference meridian, This r¿leans
is similar to that associated with the latitude
.
Potentials impressed upon the windings of po
tentiometers PI and P3 are added and impressed
upont'he primary winding of input transformer
T2 of amplifier circuit AMPI over a circuit which
mayl ire-traced from the lower terminal of the
counter and comprises the reversing gears 442 75 primary winding of transfonner T2, over the
2,406,836
brush and the upper portion of the winding of
potentiometer P3, over the brush and upper por
tion of the winding of potentiometer PI to the
upper terminal of the primary winding of trans
former TZ. Similarly the potentials impressed
upon the windings of potentiometers P2 and P3
are added and impressed upon the primary wind
ing of input transformer TIZ of ampliñer circuit
AMP2 over a circuit which may be traced from
from bus-bar 504 through resistances 5I0 and
520 to the right grids of tubes VTI and VTI I.
Potential from the 26-volt, 40o-cycle source AC
is also supplied to the primary winding of step
up transformer T3 which steps up the potential
to 200 volts. The mid-point of the secondary
winding of switching control transformer T3 is
connected to the battery bus-bar 504, one end
terminal is connected through resistance-s to the
the lower terminal of the primary winding of 10 cathode of the left unit of the rectifier tube VTZ
transformer TI2 over the brush and upper por
and to the anode of the right unit of rectifier
tion of the winding of potentiometer P4 and over
tube VT3 and the other end terminal is connected
the brush and upper portion of the winding of
through resistances to the anode of the right unit
potentiometer P2 to the upper terminal ofthe
of rectiiier tube VT2 and to the cathode of the
primary winding of transformer TI2. The po 15 left unit of rectifier tube VTS. A potential of
tentiometers PI to P4 may be of the screwdriver
200 volts is similarly applied through the switch-V
adjustable type to secure suitable adjustments of
ing control transformer TIS to the cathodes and
the feedback and signal potentials and to take
anodes of tubes VTI2 and VTI 3.
up any variations in the ratio of the transform
Relays ARI, ARZ, ARM and ARIZ are prefer
ers T2 and TIZ to the generators FGI and FG2. 20 ably of the high speed, glass sealed, merctu‘y con
The amplifiers AMPI and AMP2 may be of the
tact reed type disclosed in the application of C, E.
type disclosed in the application of R. W. Ketch
Pollard, Serial No. 487,999, ñled May 22, 1943.
ledge, Serial No. 473,083, filed January 21, 1943.
In case the output power from the air mileage
The potential impressed upon the primary
unit I is not sufficient to drive the tachometer
winding of the'input transformer T2 of ampliñer 25 generator Which in turn drives the tachometer
circuit AMPi is amplified by the dual ampliñer
motor TM, output power from the unit I may be
tube VTI and under the control of the dual diode
applied over conductor 450 through resistance
tubes VT2 and VT3 serving as full Wave rectiiiers
52! to the control grid of the dual rectiiier tube
the output from tube VTI is applied to the grids
VTI:` which in response to the signal ampliñes
of the dual triode tube VT4 to operate one or 30 such signal to operate the anode relay ARS which
the other of the relays ARI or ARE which control
in turn applies power from the battery bus-bar
the application of direct current from the source
B` to the rotor circuit of the direct current mo
tor LM. The potential impressed upon the pri
mary winding of input transformer TI 2 of the
amplifier AMP2 is ampliñed by the dual ampliiier
tube VTII and under the control of the dual
`diode tubes VTIZ and VTI3 serving as full wave
rectiñers the output from tube VTI I is applied to
the grids of the dual triode tube VTI@ to oper
ate one or the other of the relays ARE I or ARAB
which control the application of direct current
from the source B to the rotor circuit of the di
rect current motor LOM.
Potential from the source AC of 26-volt 400
cycle is stepped up to 250 volts by the transformer
T4, is rectified by the dual diode tube VT5 and
the rectified current is ñltered by the ñlter cir
cuit F and applied as a Z50-volt direct current
50d over conductor 451 to the unit I to drive the
motor therein which in turn drives a tachometer
generator to furnish the power for driving the
tachometer motor TM. Anode potential is sup
plied to the tube VTS from the Z50-volt bus-bar
ñûû‘through the winding of anode relay ARS,
cathode potential is supplied from the battery bus
bar 504 and grid potential is supplied from the
ground bus-bar 500 through resistance 522.
In order that the air position indicator may
be made sufficiently compact to be mounted in
an instrument mounting space on the usual in
strument panel of an airplane, an indicator of
45 the type disclosed at 5’ in Fig. 6 is provided.
This
indicator includes two two-directional stepping
devices of the type STP shown schematically to
the right of the indicator -and a single directional
stepping device. One of the two-directional
potential to the anode bus-bar 500. From this 50 stepping devices is capable of advancing the
pointer of the latitude minutes indicator LCm
bus-bar anode potential is applied through the
in either direction of rotation and to rotate the
windings of relays ARI and AR2 to the anodcs
input shaft of the latitude degrees counter LCd
of tube VT4, through the windings of relays ARI I
one
revolution for each degree of latitude. The
and ARI 2 to the anodes of tube VTM, through
other wheel of this counter is advanced by a deci
-resistance 50i and resistances '502 and 503 in
mal Geneva movement in the usual manner.
series to the anodes of tube VTI and through re
The other of the two-directional stepping devices
sistance 5I I and resistances 5I2 and 5i3 in series
is capable of advancing the pointer of the longi
to the anodes of tube VTII. Filament heating
tude indicator LoCM in either direction of rota
current is supplied from the direct current source
tion and to rotate the input shaft of the longi
B, over the 26-volt bus-bar 504 through resist
tude degrees counter LoCd one revolution for each
ance 505 and the filaments of tubes VTS, VTZ
degree of longitude. The other Wheels of this
and VTI in series to the ground bus-bar 506, from
counter are advanced yby decimal Geneva move
bus-bar 504 through resistance 5I5 and the lila
ments in the usual manner. The single direc
ments of tube VTí‘ä, VTI 2 and VTII in series. 65 tional stepping device drives the input shaft of
to the ground bus-bar 505 and from the bus-bar
the air- miles counter AMC the input wheel of
504 through the filaments of tubes VTM, VT4,
which makes one revolution for each ten nautical
VT6 and VT5 in series to the ground bus-bar 50B.
miles and the other wheels of which are advanced
Potential from the battery bus-bar 504 is also
by decimal Geneva movements in the usual man
applied through the grid biasing resistances 501 70 ner.
and 5I'I in parallel with the secondary windings
of input transformers T2 and TIZ to the input
grids of tubes VTI and VTI I, respectively, from
bus-bar 504 through resistances 508, 509, 5I8 and
5I|9 to the cathodes of tubes VTI and VTII and>
The indicator is provided with a reset knob E20
'for resetting the latitude counter and a reset
knob 646 for resetting the longitude counter to
indicate the latitude and longitude of a point the
latitude and longitude of which are known. A
aeoasae '
~
11
switch-button t2# is also provided for reversing
the connection of the control conductors E22
and 623 to the windings of the stepping device
which controls the latitude minutes indicator
12
'l5-I5 with the upper contact GHS associated there
withponce during each revolution of the output
shaft of the gear box 613 when the output shaft
is rotated by the motor LlVI' in one direction,
for examplefwhen a flight is being conducted
LCm and the latitude degrees counter LC‘d so
northerly in the northern `hemisphere and to
that they may be operated in the reverse direc
engage the spring Giâ with the lower contact E ll
tion when a flight is being conducted `in the
associated therewith once during each revolution
southern. hemisphere and a similar button 646 is
of the output shaft of the gear box 653 when
provided for reversing the connection of the con
trol conductors 5&2 and 5&3 to the windings of 10 the output shaft is rotated'by the motor LM’ in
the opposite direction, for example, when a flight
the stepping device which controls the longitude
is being conducted southerly in the northern
minutes indicator LoCm and the longitude de
hemisphere. The engagement of spring 5 i5' with
grees counter LoCd.
contact SI5 completes a circuit over conductor
Three motor-generator sets for controlling the
air position indicator are provided, these sets .15 622 for one stepping magnet of the stepping
device (not shown) which controls the latitude
corresponding in general to the similar sets dis
minutes indicator LCm and the latitude degrees
closed in Fig. Ll. They, however, are installed
counter LCd, and the engagement ofV spring 665
in an rassemblì-f separated from the indicator.
with contact @il completes a circuit over con
The motor-generator assembly for operating the
air miles counter AMC of the indicator comprises 20 ductor 523 for the other stepping magnet of such
stepping device.
'
a motor TM’ which, through
gearing EN!
The motor-generator set for controlling the
having a speed-up ratio of l to 4, drives the
stepping device associated with the longitude
master generator MG’ at four times the speed
minutes indicator LoCm and the longitude de
of the motor TM’ or, for example, at 729i) revo-
lutions per minute when the motor TM’ is oper
ating at a speed of 1800 revolutions per minute.
The master generator MG’ is a two-phase, 400
cycle induction motor functioning as an induc
grees counter LoCd comprises a split ñeld series
across the control phase 60| of this generator and
has the same frequency as the Li90-cycle, ZfS-volt
supply AC of alternating current which is con
nected to its iixed phase winding 6&2. The gen
erator may be considered as a transformer, whose
ratio is dependent on the rotational speed. The
motor TM' through the gearing 5E!! and the re
duction gear box 6&3 having a reduction gear
ratio of i440 to i, rotates the cam '5&4 which once
connected to the source AC of 40G-cycle current
and its other phase winding 628 connected across
the Winding of rotor RI ' of the magnetic resolver
MRM’. One brush of motor LOM’ is connected
over battery bus-bar 564 to the positive terminal
of battery B` and the other brush of the motor
connected direct current motor' LOM’ coupled
directly with the rotor of the feedback generator
FGQ’. This feedback generator is a two-phase,
40G-cycle induction motor functioning as a gen
tion generator. A potential whose amplitude is
proportional to the rotational speed appears 30 erator and has one of its phase windings 621
per revolution establishes a circuit over conduc- ~
is connected through the two field windings 63!
and 632, respectively and over conductors §29
and 430 with the armatures of relays ARH and
ARIZ located in the output side of the amplifier
circuit AMPZ of Fig. 5. The rotor shaft of motor
tor 52! and through the winding of the stepping
LOM’ is also connected to the input shaft of the
magnet (not shown) which advances the input
reduction gear box 633 which has a reduction
shaft of the air miles counter AMC.
gear ration of 360 to 1 and on whose output shaft
The motor-generator set for controlling the
stepping device associated with the latitude min 45 the’cam 634 is mounted. Cam 634 is arranged to
engage the spring 635 with the upper contact 636
utes indicator I_«Cm and latitude degrees counter
associated therewith once during each revolution
L-Cd comprises a split field series-connected direct
of the output shaft of the gear box 533 when
current motor LM' coupled directly with the
the output shaft is rotated by the motor LOM’
rotor of the feedback generator FG! '. This feed
back generator is a two-phase, 40G-cycle induc .50 in one direction, for example, when a night is
being conducted easterly of a reference meridian
tion motor functioning as a generator and has one
and to engage the spring 635 with the lower con
of its phase windings 535 connected to the source
tact 531 associated therewith once during each
AC of 40G-cycle current and its other phase wind
revolution of the output shaft of gear box 633
ing 69d connected over conductors 401 and £08
with the winding of the potentiometer P3 asso A55 when the output shaft is rotated by the motor
LOM’ in the opposite direction, for example when
ciated with the input side of the amplifier .unit
a flight is being conducted westerly in the east
AMP! of Fig. 5. One brush of the motor LM’
ern hemisphere. The engagement of spring 635
is connected over battery bus-bar 504 to the posi
with contact B35 completes a circuit over con
tive terminal of battery B and the other brush
of the motor is connected through the two field 60 ductor 642 for one stepping magnet of the step
ping device (not shown) which controls the lon
windings (5i i and 6 i2, respectively, and over con
gitude minutes indicator LoCm and the longitude
ductors ¿its and ¿Iii with the armatures of relays
degrees counter LoCd and the engagement of
AR! and ARZ located in the output side of the
spring 635 with contact B31 completes a circuit
amplifier circuit AMPI of Fig. 5. In this con
nection it is to be noted that when the amplifier 65 over conductor E43 for the other stepping magnet
of such stepping device.
Y
circuits of Fig. 5 are used with the modified
The master generator MG' and the two feed
form of apparatus disclosed in Fig. 6, the front
»back generators FGI' and FGZ’ are enclosed in
contacts of relays ARI, ARE, ARI l and ARIZ are
a common housing 650 which closely embraces
connected to ground and the back contacts are
them whereby they are all similariy subjected
left unconnected.
`
to the same magnetic influences.
The rotor shaft of motor LM’ is also connected
Since a synchro-receiver such as is shown at
to the input shaft of the reduction gear box SIS
SR in Fig. 4 may not have sufñcient torque to
on the output shaft of which cam 6M is mounted.
operate a magnetic resolver, vsuch as MR2 also
The gear box @i3 has a reduction ratio of 1440 to
4, a compass servo device indi
1. The cam 6M is arranged to engage spring` 75 shown in
2,408,836
13
14
cated by the box CS in Fig. 6, may be provided
which may in the well-known manner be con
openings in the face of the indicator unit 5. It
will also be assumed that previous to the con
trolled by a synchro-transformer coupled with
templated night the airplane has been flown
a synchro-generator driven by either a mag
netic or earth inductor type compass control.
The compass servo in turn `drives the synchro
miles counter AMC.
It will be assumed that a night is made in
transmitter which is coupled with the synchro
the direction indicated by the line FA in Fig. 3
15,865 nautical air miles as indicated by the air
receiver associated with the course indicator CI.
with a true compass course of CN degrees and at
rI‘his course indicator is mounted on the instru
such a true air speed that the distance traversed
ment panel of the airplane. The compass servo 10 at the time an observation is to be made, may be
also rotates the rotor R2’ of the magnetic re
indicated by the vector FA. The latitude distance
solver MR2’.
component FB of the vector FA is therefore FA
The horizontal stator winding 64B of the mag
cos CN and the distance BA or p along the latitude
netic resolver IWRZ’ is connected in series with
parallel through the point A is therefore FA sin
the winding of potentiometer P2 in Fig. 6 over 15 CN. The air speed is measured by the air mileage
conductors 45| and 452 and the vertical stator
winding'GiH is connected in series with the wind
ing of potentiometer PI over conductors 45|
and 453. The winding of the rotor R2’ of this
magnetic resolver is connected in series with 20
the winding 60| of the master generator MG' so
that a potential E0 is applied across the Winding
of the rotor which varies with the air speed of
the night and since the rotor winding is oriented.
by the compass servo CS in accordance with the 25
true compass bearing angle CN of the night, a
potential is derived from the horizontal winding
B455 of this resolver which has a value of E0 sin CN
and a potential is derived from the vertical wind
ing 64| which has a value Eo cos CN.
The magnetic resolver MRI', previously re
unit | which operates the tachometer motor TM
to drive the master generator MG at an angular
velocity wo commensurate with the air speed or
wo=KuV¢ where the true airspeed is expressed as
Vt. As the night progresses from the point of
take-olf F along the vector direction FA, the air
miles counter AMC is driven through the reduc
tion gear box 403 and the reduction gears 464 to
>add the nautical air miles which the airplane nies
to the record on the counter at the point of take
oiî. The pilot noting the reading of the counter
at any time and by subtracting therefrom the
initial reading may ascertain the number of air
miles
30
ferred to, has a rotor RI ’ which is rotated by the
flown.
’
«
Y
If desired the counter AMC could be provided
with a means for disconnecting the counter from
its connection with the reduction gear box 493
and with means for resetting the counter to zero,
similar to the means associated with the latitude
two-directional stepper STP under the control
of contacts operated by a cam (not shown) on
the input shaft of the latitude degrees counter 35 counter LC, so that the air miles flown on any
LCd of the air position indicator 5’. The wind
night could be ascertained directly from the
ing of this rotor is energized by potential im
counter without the necessity of making a cal
pressed thereon from the stator winding €523 or".
the feedback generator FGZ’. Two windings of
culation.
‘I‘he generator MG in operating generates a
.its Y-connected stator are connected across the 40 potential in the circuit extending through the
input of the amplifier AMP?, which in the well
vertical stator winding 40|, the vertical stator
windings of feedback generators FGI and FGZ
known manner serves to amplify the output po
tential of the magnetic resolver MRl’ and to
and the winding of rotor R2 of the magnetic
apply such amplified potential across the primary
winding of transformer Tl of Fig. 5, the sec
ondary winding of which transformer is bridged
speed.
across the winding of potentiometer P4.
receiver SR in response to the true compass bear
resolver MR2 which is a measure of the air
Since the rotor R2 of the magnetic re
solver is angularly positioned by the synchro
The output potential from the stator winding
ing of the night as determined by the flux gate
SEI of the master generator MG’ is also impressed
compass unit 8 or the auxiliary compass control
across the input side of amplifier AMPA which in 50 unit I2, the rotor winding will assume a position
the well-known manner serves to amplify this
with respect to the stator windings of the mag
potential and to apply such amplified potential
netic resolver commensurate with the true course
across the primary windings of transformers T3
angle CN (no compensation being made for the
and T|3 of Fig. 5.
eifect of wind). Since the potential impressed
The apparatus employed in embodying the in 55 upon the rotor winding is in accordance with the
vention having now been described, the manner
air speed Vt of the night in the vector direction
in which the apparatus functions and particu
FA, which may be expressed KlwozEo, the po
larly the apparatus disclosed in Figs. 4 and 5 will
tential derived from the stator winding 44|, which
nrst be described. It wil be assumed that the
airplane in which the air position indicator isA 60
installed starts a flight from a position of 00
degrees 00 minutes latitude and 095 degrees 30
minutes longitude in the eastern hemisphere and
that the flight is to proceed in the easter-n and
northern hemispheres. The pilot knows the lati 65
tude and longitude of the position of take-off and
therefore sets the latitude and longitude counters
LC and LOC by the operation of the reset knobs
426 and 448 in the manner previously described so
that they indicate this position as disclosed in 70
Fig. 4. He also sets the knobs 424 and 444 so
that the counters will be operated in the proper
direction for the contemplated night, the posi
tion in which the knobs are set appearing as N
and E on the shutters as viewed through the
v75
may be identified as E1, may be expressed as
E1=E0 cos CN and the potential derived from
the stator winding 440, which may be identified
as Ez, may be expressed as E2=Eo sin CN. If
now the vector FA of Fig. 3 be considered the dis
tance vector of the flight it may be expressed as
having a potential Eat. Then the distance vector
FB of the night position A will be FB=L=E1t=E0t
cos CN or L=Eot cos CN and the vector BA or p of
the night position A will be p=E2t=Eot sin CN.
The potential from the stator Winding 44D,
having the value E1 or En cos CN, is impressed
across the winding of potentiometer PI and a
potential derived therefrom is impressed through
the transformer T2 upon the input circuit of
amplifier tube VTI, is amplined by such tube and
is impressed through condenser 521 and thence
.2,406,836
.16
tiometer P13, lower than the signal potential
through resistances 528 and 5729 in series to the
v whereupon the ampl-iiìer AllEPI‘v/ill again func
upper grid of tube VT4 and in a parallel path
through resistances 530 and 524 to the lower grid
of tube VT4. The output of tube VTI is shunted
by two bridge circuits. The dual diode tube VT2
together with the two halves of the secondary
winding of transformer '1T-_3 form one bridge and
the dual diode tube VTS and the two halves of
tion to operate relay ARE to again establish the
circuit of the motor Ll l.
The motor LM will
again bring generator FGQ up to a speed atwhich
the feedback potential applied across the wind„
ing of potentiometer P3 again balances the signal
potential Eo cos CN.
In this manner the motor
attains a substantially constant speed at which
the secondary winding of transformer vT3 .form
the other bridge. The imnedances of vthese 10 the :feedback generator FGI has an output poten
tial, herein designated E’r, which equalsthe po~
bridges are controlled by the 40G-.cycle current of
_a reference phase obtained through thewind
te tial Eo cos CN. Since the motor LM drives the
tude counter LC as previously described, the
counter will be advanced at such a speed w1 that
The impedance of the ñrst bridge is connected
between the junction of «resistances 52,8 and 52e 1.5 after the time t required `for the airplane to ily
from the point F’ to the point A or a latitude dis
and the mid-point of the secondary Winding of
tance Erb or Eef; cos Cn, it will indicate in degrees
transformer T3 which is connected through the
and minutes the latitude distance L of the posi
iilanient battery B to ground. The impedance of
tion A of the airplane.
the second bridge is connected between the junc
It is a well-known rule of geography that the
tion of resistances 530 and 524 and the midfpoint
ing of transformer T3 from the source AC. '
of the secondary winding of transformer `T3
and the potential drops' due to the incoming sig
nal current in these impedances are applied to
the unser and lower gridsrespectively of tube
VT4.
Due to the noline of the diodes VTZ and VTS
of. the. bridges, the bridges are conducting on
change in longitude equivalent to a given depar
turev varies in accordance with the secant of the
average latitude. The basis for this'ass'ertion will
be apparent from the following discussion con
no ‘en
alternate half cycles Of the reference frequency.
sidered in connection with the diagram of Fig. 3.
It will be assumed that the longitude of point A
with respect to point F is to be determined. BA
.and FE’are similar arcs of two circles and are
' proportional to the radii of the circles. There
During the non-conducting half cycles the signal
potential drop in either bridge is very small com 30 fore, if BA be designated p and FE be `designated
llc or the longitude of the point A, then
pared with the value during the conducting half
cycles, When the ñrst bridge is conducting the
L
e
signal on the upper grid of tube VT4 will be either
positive or negative depending on whether the
signal is in phase or phase opposition to the ref
erence frequency.
VIn other words the grid re
ceives either the positive or the negative pulses
of the signal depending on the phase of the sig
nal with respect to the reference frequency. Sim
ilarly, when the second bridge is conducting, that
is,2 during, the alternate half cycles of the refer
ence frequency, the lower grid of tube VT4 re
Now the latitude of the point A is the angle
BOF which is equal to the angle AOE», but angle
vA0E is equal >to the angle OAC of the right angle
triangle OAC. If now the angle OAC be desig
nated A we have in the triangle OAC
AC
r
AC=A0 cos À or cos À-ÃÖ-E
(2)
Substituting Equation 2 in Equation 1 we have
ceives either the negative or the positive signal
pulses according to the phase of the signal.
p=Lo cos À or LQ= _p__ or Lor-.p sec À
(3)
cos )\
`If it be assumed that the incoming signal and
the reference frequency are so phased that the
A is the latitude angle so it follows that
loWCl‘ unit of tube VT4 becomes conducting relay
AR? operates in a circuit from battery on the bus
Lo
or Lo=p sec L
bar .599 through the winding of relay ARZ, over
50
the anode-cathode path through the lower unit
In the circuits under discussion the value of p
of tube VT4, to the positive side of the ñlament
in terms of potential is determined by the poten
battery and thence to the ground bus-bar 506.
tial derived frorn the horizontal stator winding
lïtelaj.7
upon operating establishes a circuit for
of the magnetic resolver MR2 and has a value asn
sumed to be E2 or Eo sin CN and therefore the po
55
through resistance 5245, over the front contact of ~ tential value of p may be expressed Eo sin CN. The
the motor LM which may be traced from battery B
relay ARZ, `Cimductor ¿m9, through the rotor circuit
of motor LM, over the normal contacts of limit
switch LFS, conductor 4Ill, and over the back
contact of relay ARI to the ground terminal of
battery B.
potential value of the latitude L has already been
determined as E’r or Eo cos CN where E’1 is the
output potential of the feedback generator FGI
when such generator is operating at a speed w1
Motor LM is thus operated to drive Y 60 such as to satisfy the latitude vector L. As a
the _feed back generator FGI.
consequence the rotor RI has been positioned
through the latitude angle A. Therefore in terms
the generator FG! is running at such a speed that
of potential and considering the output potential
the potential output from its stator winding 40B 6.5 of the feedback generator FG2 to be E’z when
yliyirlffror applied across the winding of potenti
such generator is operating at a- speed such as to
ometer P3 balances the signal potential E1 or En
satisfy the longitude Vector Lo, Equation 3 may
cos CN applied from the vertical stator winding
be Written in terms of potential as
ft'lI of the magnetic resolver MR2 across the wind
E() Sin CN
ing of potentiometer P i, at which time the ampli
' ~ The motor LM will quickly pick up speed until
fier AMP-I will receive no vsignal potential and _re- ‘
lay ARÈ will cease operating to open the circuit
ci in otor LM.
(4)
Referring now to Figs.V 4 and 5, potential from
The motor will then tend to slow
clown whereupon the generator FGI Will apply a
tbe stator winding 411D having the value E12 or Eo
feedback potential across the winding of poten
tiometer P2 and a potential derived therefrom is
sin CN is impressed across the winding of poten
17
2,406,836`
impressed through the transformer TI2 upon the
input side of amplifier tube VTI I, is amplified by
18
such potential E’2 across the rotor winding of the
magnetic resolver MRI. It will be recalled that
suchtube and is impressed through condenser
531 and thence through resistances 538 and 539 in
the rotor R1 of this magnetic resolver is rotated
in response to the operation of the latitude mo
series upon the upper grid of tube VTM and in a
tor LM. The angle through which the rotor RI
parallel path through resistances 540 and 534
is turned is then equal to the angle subtended
upon the lower grid of tube VTM. It will be as
by the arc of latitude as appears by reference to
sumed that the incoming signal potential for a
Fig. 3 in which the angle of latitude is designated
flight toward the east is in phase with the poten
as li; Consequently, a potential is derived from
tial impressed upon the left portion of the sec 10 the stator windings of the magnetic resolver MRI
ondary winding of transformer TIS but out of
which has a value E’2 cos A. This potential is
phase with the potential impressed upon the right
then impressed from the stator windings of mag
portion of the secondary winding of such trans
netic resolver MRI, over conductors 454- and 455
former.
upon the primary winding of transformer TI , the
The output of tube VTII is shunted by' two 15 secondary winding of which transformer is con
bridge circuits, the dual diode tube VTI 2 together
with the two halves of thesecondary winding of
transformer T53 form one bridge and the dual
nected in series with the winding of potentiome
ter P4. Thus a potential equal to E’z cos A is
impressed upon the winding of potentiometer P4
which is opposite in phase to the potential equal
diode tube VTI3 and the two halves of the sec
ondary winding of transformer TI3 form the 20 to Eo sin CN impressed upon the winding of po
other bridge. The impedances of these bridges
tentiometer P2. These potentials tend to balance
are controlled by the 40G-cycle current of a ref
each other and when the feedback generator
erence phase obtained through the windings of . FG2 reaches a speed such that its output poten
transformer TI 3 from the source AC'.
tial E’z is of such a value that E’s cos >`=Eo sin CN
The impedance of the first bridge is connected
then the amplifier circuit AMPZ receives no input
potential and relay ARI2 releases to open the
between the junction of resistances 538 and '539
circuit of motor LoM.
and the mid-point of the secondary winding of
Motor LOM will then tend to slow down where
transformer TI3 which is connected through the
filament battery B to ground. The impedance of
upon the generator FGZ will apply a feedback
the second bridge is connected between the junc- » potential across the winding of potentiometer P4
lower than the signal potential Et sin CN Where
tion of resistances 540 and 534 and the mid-point
upon the amplifier AMPZ will again function to
of the secondary winding of transformer TI3 and
operate relay ARI2 to again establish the circuit
the potential drops due to the incoming signal
of motor LoM. The motor LOM will again bring
currents in these impedances are applied to the
upper and lower grids, respectively, of tube VTM. - the generator FG?. up to a speed at which the
feedback potential applied across the winding of
Due to the poling of the diodes VTIZ and VTI3
potentiometer P4 again balances the signal po
of the bridges, the bridges are conducting on al
tential Eo sin CN. In this manner the motor
ternate half cycles of the reference frequency.
attains a substantially constant speed at which
During the non-conducting half cycles the signal
the feedback potential 12’2 cos A is generated.
potential drop in either bridge is very small com
Since the motor LoM also drives the longitude
pared with the value during the conducting half
counter LoC as previously described, the counter
cycles. When the first bridge is conducting the
will be advanced at such a speed that after the
`signal on the upper grid of tube VTM will be
time t required for the airplane to fly from the
either positive or negative depending on whether
the signal is in phase or in phase opposition to 45 point F to the point A or a longitude distance
the reference frequency. In other words the grid
receives either the positive or the negative pulses
of the signal depending on the phase of the signal
with respect to the reference frequency. Simi
or the longitude distance Lo, it will indicate in
larly, when the second bridge is conducting, that 50 degrees and minutes the longitude of the position
is, during the alternate half cycles of the refer
A of the airplane.
ence frequency, the lower grid of tube VTM re
The modiñed form of air position indicator dis
ceives either the negative or the positive signal
closed in Figs. 5 and 6 functions in substantially
impulses according to the phase of the signal.
the same manner as the indicator just described.
If it be assumed that the incoming signal and 55 The chief difference between the two indicators
the reference frequency are so phased that the
is ‘that the air miles, latitude and longitude
counters of the air position indicator disclosed in
lower unit of tube VTM becomes conducting, re
Fig. 6 are remotely controlled from the motor
lay ARIZ operates in a circuit from battery over
generator sets by stepping impulses transmitted
the bus-bar 50B, through the winding of relay
ARI2, over the anode-cathode path through the 60 to the indicator whereby it becomes possible to
locate the indicator on the instrument panel and
lower unit of tube VTM, to the positive side of the
to locate the motor-generator sets in any conven
filament battery and thence to the ground bus-bar
ient place in the airplane. While in the form of
505. 1Relay ARIZ upon operating establishes a
the invention disclosed in Fig. 6 split field series
circuit for the“ motor LoM which may be traced
from battery B through resistance 536 over the 65 connected direct current generators have been
indicated it will be evident that magneto type
front contact of relay ARI2, conductor 43B,
generators such as are disclosed in Fig. 4 could
through the rotor circuit of motor LOM, over con
be` used.
ductor 429 and the back contact of relay ARII to
It is also to be noted that the horizontal stator
the ground terminal of battery B. Motor LOM is
thus operated to drive the feedback generator 70 windings 685 and 621 of the feedback generators
FGI' and FGZ’ are energized from the 400-cycle
FGZ
The motor LoM quickly picks up speed where
source AC rather than from the potential derived
from the stator windings of the master generator
upon Vthe generator FG2 develops an output
potential E’z in its stator winding 428 propor
as disclosed in Fig. 4. In this modification, how
tional to the air speed potential Eb and applies 75 ever, a potential generated by the master gen
2,406,836
19
erator MG', which varies in accordance with the '
air speed is made effective to determine that the
feedback generators FGI? and FGZ’ shall gen
erate the same potential as the master generator
20
the sine and cosine of the course angle, means
controlled by said cosine potential for operating
said latitude indicator, a magnetic resolver hav
ing a rotatable rotor Winding rotatable by said
when they run at the same speed as the master
latter means for deriving a potential which
generator by the application’of the output po
tential from the master generator, through the
amplifier AMPÁ’., to the speed control amplifier
circuits AlVlIPi and AMP2 through the windings
of the switching control transformers T3 and TIS.
What is claimed is:
varies in accordance with the cosine of the lati
l. In an air position indicator for an aircraft,
an indicator for indicating the instant number of
tude angle, and means controll'edjointly by said
latter potential and by said sine potential for op
erating said longitude indicator.
4. In an air position indicator for an aircraft,
an indicator for indicating the instant number of
air miles fiown, and indicator for indicating the
instant longitude position of said aircraft, an in
dicator for indicating the instant longitude posi-v
air miles ijoyvn, an indicator for indicating the
instant latitude position of said aircraft, anindi 157 tion of said aircraft," means for operating said
first` indicatorfin accordance with the air speed
cator for indicating the instant longitude posi- Y
tion of said aircraft, means" for operating said
first` indicator in accordance with the air speed
of the aircraft, means for generating a potential
commensurate with the air speed of said air
craft, means controlled in accordance with the
true compass course of the flight for deriving
of said aircraft, means for generating a potential
commensurate witlrthe air speed of said air
craft, means controlled in accordance with the
true compass course of th'e flight for'resolving
said potential into potentials which vary with the
sine and cosine of the true course angle, a motor
for driving said latitude indicator, a feedback
generator driven thereby, a speed control de
values of said potential which vary in accordance
with the sine and cosine lof, the course angle,
means controlled by said cosine potential for op 25 vice responsive to the output potential of said
generator and to the cosine component of said
erating said latitude indicator, means controlled
air speed potentialfor causing said motor to drive
. by said latter means for generating a potential
said latitude indicator to continuously indicate
which varies in accordance with the cosine of the
the latitude position of said aircraft, a motor for
latitude angle, and means controlled jointly by
-said latter potential and by said sine potentialA 30 Vdriving said longitude indicator, a feedback gen
erator driven by said latter motor, a magnetic
for operating said longitude indicator.
resolver having a rotor Winding >energizable by
2. In an air position indicator for an aircraft,
the output potential from said latter generator
an'indicator for indicating the instant number
and rotatable by said first motor for deriving a
of air miles flown, an indicator for indicating the
potential from the output potential of said latter
instant latitude position of said aircraft, an in
generator Which varies in accordance with the
dicator for indicating th'e instant longitude posi
cosine of the latitude angle, and a second speed
tion of said aircraft, means for operating- said
control device responsive to said latter potential
first indicator in accordance with the air speed
and to the sine component of said air speed po
of said aircraft, means for generating a potential
tential for causing said latter motor to drive said
commensurate with the air speed of said aircraft, 40 longitude indicator to continuously indicate the
means controlled in accordance With the true
longitude position’of said aircraft.
compass »course of the flight for resolving said
5. In an air position indicator'for an aircraft,
potential into potentials which vary with the
an indicator kfor indicating the instant number
Sine. and cosine of the true compass angle, a mo
of air miles flown, an indicator for indicating the
tor for driving said latitude indicator, a feed 45 instant latitude position of said aircraft, an in
back generator driven thereby, a speed control
dicator for indicating the instant longitude posi
device responsive to the output potential of said
generator and to the cosine component of said
air speed potential for causing said motor to
drive said latitude indicator to continuously indi
cate the latitude position ofl said aircraft, a mo
tor for driving said longitude indicator, a feed
back generator driven by said latter motor, means
operable by said first motor for deriving a poten
tial from the output potential of said second gen
erator which varies in accordance with the cosine
of the angle of latitude, and a speed control de
vice responsive to said derived potential and to
the sine component of said air speed potential
tion of said aircraft, means'for operating said
first indicator in accordance with the air speed
50.. of said aircraft, means for generating a potential
commensurateV with the air Vspeed of said air
craft, means controlled in accordance with the
true compass course of the flight for resolving
said potential into potentials which vary with the
sine and cosine of the true course angle, a mo
tor for driving said latitude indicator, a feedback
generator driven thereby, a thermionic speed
control circuit responsive to the feedback poten
tial of said generator and to the cosine compo
for causing said latter motor to drive said longi 60 nent of said air speed potential for causing said .
motor to drive said latitude indicator to contin
tude indicator to continuously indicate the lon
uously indicate the latitude position of said air
gitude position of said aircraft.
craft, a motor> for driving; said longitude indi
3. In an air position indicator for an aircraft,
cator, a feedback generator driven by said latter
an indicator for indicating the instant number
motor, means operative by said iirst motor for
of air miles ñovïn, an indicator for indicating the
deriving a potential from the output> potential of
instant latitude position of said aircraft, an in
said second> generator which varies in accordance
dicator for indicating the instant longitude posi
with the angle of latitude, anda second thermi
tion of said aircraft, means for operating said
onic speed control circuit responsive to said de
first indicator in accordance with the air speed
rived potential and to the sine component of said
of said aircraft, means for generating a potential
air speed potential for causing said latter motor
commensurate with the air speed of said air
to drive said longitude indicator to Vcontinuously
craft, means operative in accordance with the
indicate the longitude position of said aircraft.
true flight course of the iiight for deriving values
WILLIAM H. T. HOLDEN.
of said potential which varf,r in accordance with'
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