USRE23627E - Apparatus fob simulating radio - Google Patents

Description

Marchv 10,, 1953 at. DEHMEL 23,627

APPARATUS FOR SIMULATING RADIO NAVIGATION AIDS Original. Filed Nov. 12; 1947 4 Sheets-Sheet 1 A der/l INVENTOR.

(WK? C PEI/MEL BY 7Q;

ATTORNEY.

March 10, 1953 R. c. DEHMEL 23,627

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March 10, 1953 R. c. DEHMEL APPARATUS FOR SIMULATING RADIO NAVIGATION AIDS 4 Sheets-Sheet 3 Original Filed Nov. 12, 1947 whemk wxn INVENTO'R. 176 715 C ,DEFMEZ ATTORNEY};

4 Sheets-Sheet 4 R. C. DEHMEL March 10, 1953 APPARATUS FOR SIMULA'IING RADIO NAVIGATION AIDS Original Filed Nov. 12, 1947 m M H N H N w E w CPA 8 ny at Reissued Mar. 10, 1953 APPARATUS FOR SIMULATIN G RADIO NAVIGATION AIDS Richard Carl-pehmel, Short Hills, N. J.

Original No. 2,560,527, dated July 10, 1951, Serial No. 785,225, November 12, 1947. Application for reissue March 26, 1952, Serial No. 278,664

Hatter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

24 Claims.

This invention relates to a method of and apparatus for simulating radio navigation aids, particularly omni-directional radio navigation aids and compass locator equipment of the automatic direction finding type used in aircraft.

The comparatively new omni-directional range (ODRl-radio facility uses a very high frequency (VHFY transmitter which radiates signals for giving an infinite number of courses radiating from the radio station, as contrasted with the conventional low frequency A and N radio range which has but four radiating direction beams. Radio receiving apparatus in the aircraft when tuned to a particular ODR station is designed to give a direct (or reciprocal) reading of the aircraft bearing with respect to the station without reference to the instant heading of the aircraft, 1. e. the ODR receiver is position, not heading sensitive. In practice thisstation bearing may be coordinated with the aircraft magnetic compass heading in order to give both magnetic heading information and a direct pointer course to the station in the manner of well known automatic direction finder (ADF) apparatus. Furthermore this station bearing may be co-ordinated with distance measuring (DME) for obtaining a ilx" on a single ODR station, the distance to the station being determined by the time required for a radio signal to travel from the plane to the station and reequipment turn. In an alternative arrangement, the radial. i. e. hearing from station to plane, to be flown is set into a so-called radial selector" that is related to the vertical needle of the standard cross-pointer instrument to indicate deviation from the radial.

A particularly practical way of using the omnidirectional range in combination with DME has been proposed whereby offset course computing is greatly facilitated so that simply by determining known bearing and distance data from his maps the pilot can set his computer and fly directly by pointer indication from any one point to another within the range of a given ODR station. As in the case of conventional A and N radio ranges, ODR stations are located at various positions about the country so that crosscountry flying may be done by tracking on consecutive legs in respective omni-directional,

' A principal object of this invention is to provide an improved method of and apparatus for simulating offset course computing and indicating equipment of actual aircraft for pilot training and also for simulating'xthe receiving and indicating equipment for-providing automatic direction finding data; and itis a special feature of my invention that the same apparatus is useful to provide the simulation of both equipments above referred to.

Another important feature of my invention is that it may be used in combination with fully automatic radio range and ADF training apparatus 0f the character described in my co-pending patent applications Serial No. 607,333 filed July 27, 1945, for Aircraft Training Apparatus and Serial No. 678,553 filed June 22, 1946, for Radio Training System for Aircraft Pilots respectively, for conjointly giving A and N range signals, instrument landing system (ILS). Z marker and fan marker signals, compass locator and all the various radio navigation aids including dual ADF operation cross-country and consecutive omni-directional and offset course tracking. The first mentioned application has matured into Patent No. 2,529,468 dated November 7, 1950, and the second named application has become Patent No. 2,533,361 dated Decembes 12, 1950.

The invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawings Fig, 1 is a diagram illustrating offset course navigation with respect to an ODR station;

Fig. 2 illustrates the pilots computer panel with dials for setting up the offset course problem;

Fig. 3 illustrates the pilot's instrument panel for giving direction, tracking and distance information;

Fig. 4 is a partly diagrammatic and schematic layout of flight computing and charting apparatus including means for deriving voltages for operating the oifset course computer of the present invention;

Fig. 5 is a vector diagram illustrating vector rangement of the RMI apparatus conforming to general practice; and

Fig. 9 illustrates schematically the use of duplicate apparatus.

The operation of ODR equipment in actual aircraft for oifset course computing will be generally described with reference to Figs. 1 to 3. In Fig. 1 the location of an ODR transmitting station is indicated at T and it will be assumed that an airplane is located at an origin point 0 and the pilot wishes to fly to a destination point D along the path OD which is offset with respect to transmitter T, the points 0 and D being within the range of VHF signals from the station. The pilot therefore can readily determine in advance from his maps certain essential data such as the offset course bearing 0,. the distance TD from station to destination and a so-called angle-of-radial 6 which is the bearing of point D from station T; also the co-bearing of station T from point D thus defining point D as a compass locator station." This data is set into the computer represented by the panel I, Fig. 2, by means of respective dials, the dial 2 representing adjustment for tuning in the ODR station frequency, dial 3 the desired course bearing 0, dial 4 the radial angle 6 and dial i'the distance TD.

when the above computer dials of Fig. 2 are thus adiusted for the course 0D, the offset course computer in the aircraft instruments on the tracking information panel B of Fig. 3 as the course is flown to give the following information. The radio magnetic indicator (RMI) indicated at I, Fig. 3, is a radio compass indicator somewhat similar to the standard ADF equipment and gives the magnetic compass heading at the fixed index or "lubber line" 'lc from the rotatable dial card la, the pointer 1b being vunder control of the offset course or ADF computer to continuously point to the destination bearing from the aircraft. The vertical needle 8 of the conventional crosspointer instrument 9 shows the direction and amount of lateral course OD and the pointer of meter III shows on the "To scale the distance still to go from the instant position of the airplane to the destination along the line OD. Accordingly for accurately flying the course On regardless of wind drift it is necessary merely to hold the course bearing indicated by the RMI meter at angle 0 or to keep the vertical cross-pointer needle centered. If the aircraft drifts of! course to a point 0' for example the distance-to-go meter Ill indicates the distance to point D along the parallel course O'D', the line D'D being perpendicular to 0D and the distance D'D being represented by deflection of the vertical crosspolnter. whgn tl e aircraft passes point D the will actuate the.

displacement away from the pointer of distance meter ill moves through zero For solving simpler problems, such as hom ing" not involving offset course computation, as where the pilot wishes to fly directly from point.

0 to the station along track OT, there is sometimes provided a combined meter for showin whether the flight is toward or away from the station T in addition to giving distance and bearing information. This meter uses a manually operated azimuth set crank. and has a shutter operable to uncover a reciprocal bearing reading and to cover the original bearing reading when the aircraft passes beyond the station. In' the above homing problem the dial 5 of Fig. 2 is set at zero since the station and destination points are identical. For this case the course bearing 0 is the angle measured clockwise from the north reference direction at point 0 to the course OT, the setting of dial 4 being immaterial since dial 5 is set at zero.

Where an instrument landing system (ILS) of well known type is to be used in a subsequent approach to a landing fleld, the cross' pointer meter may be used in combination with the glide and localizer of that system and the RMI can be used as an ADF indicator or compass locator stations.

Referring now to Fig. 4 a computing and charting system is illustrated including resolving and integrating apparatus for charting the simulated flight and for obtaining position voltages to be used in the offset course computing apparatus of Figs. 6 and 8. The apparatus of Fig. 4 is shown schematically and will be described briefiy since it is specifically disclosed and described in my aforesaid application S. N. 607,333. The input data may be obtained from the simulated air speed meter l I, magnetic compass indicator l! and the wind drift velocity and direction dials I! and M respectively. The instruments It and I2 may be operated in accordance with the operation of well known ground trainer apparatus, such as that disclosed in my Patent No. 2,366,603 granted January 2, 1945, for Aircraft Training Apparatus. The wind drift dials l3 and I4 are set manually to simulate any given condition of wind drift.

The "air speed resolver which is energized bya derived voltage proportional in magnitude to the air speed V is adjusted in accordance with the compass heading angle a. for obtaining component voltages Ev sin a and Ev cos a designated as V: and V, respectively to represent velocity along the x and y axes respectively of a reference Cartesian coordinate system, and the wind drift resolver which is adjustable according to the wind direction 8 similarly resolves the voltage representing the wind velocity W into the components Ew sin :1 and Ev cos is designated respectively as Wx and W The aforesaid voltage components are all fed to a summing and integrating system as indicated for summing the x velocity components Va and W: and the y velocity components Vy and W, to give resultant x and y velocity values representing ground speed. These ground speed components are then integrated as to time for producing voltages representing the x and y coordinate values for the instant flight position on a chart.

Where a polar coordinate chart is used the aforesaid x and y position voltages may be converted to polar coordinate values by means of voltage resolvers such as the X and Y cosinusoidai cam potentiometers II and Ill which are controlled by the shaft ll of the rotatable polar chart II. The center of the chart, 1. e. shaft l1, represents the position of the radio station Tand the chart is positioned according to the bearing of the aircraft from the station by means of a servo mechanism.

The radial distance of the airplane fromthe station is represented by the position of the pen I9 which operates radially with respect to point T. The chart shaft II which positions the polar chart l3 and slider contacts of the resolverpotentiometers l5 and I6 is operated as indicated by va two-phase motor the control winding 2| of which is energized from the azimuth summing amplifier 22. Assuming, for purposes of specific illustration, that the instant position of the aircraft 0', Fig. 7, coincides with the destination D, then the inputs to amplifier 22 include a negative velocity feed-back voltage at input conductor 23 from the motor-driven two-phase generator 24, a voltage +Ex cos 6 at input conductor 25 from slider contact 26 of the X resolver and a voltage Ey sin 6 at input conduetor 21 from slider 23 of the Y resolver.

When these x and y voltages of opposite sign are equal, the output of the amplifier is zero and the position of the chart corresponds to the correct azimuth angle 6 as diagrammatically shown by Fig. 5. That is, for a condition wherein x cos 6=y' sin a, there can be but one stable value for angle 6. The amplifier, Fig. 4, is also provided with a gain control circuit 29 including a resistance 30 and is varied according to range as indicated for obtaining uniform operation of the azimuth motor 23 at all values of Ex and E; potentials applied to potentiometers I5 and Hi, Fig. 4. The voltage applied to winding 2| differs 90 in phase from the Eac signal on winding 2|, this phase shift being obtained within the amplifier 22 in well known manner. The pen I3 is positioned by means of a lead screw 3| and two-phase motor 32, the control winding 33 of which is energized by the output of the range summing amplifier 3|.

Referring again to Fig. 5 it will be apparent that the range, or distance TD in this instance is x sin 6+y cos 6. Hence, the amplifier inputs include a negative velocity feed-back voltage at conductor 35 from the motor-driven two-phase generator 36, a'voltage +E= sin 6 at conductor 31 from the slider 38 of the X resolver, a voltage +E: cos 6 at conductor 39 from slider 40 of the Y resolver, and finally a balancing voltage at conductor ll from the range controlled potentiometer 42. As explained in my aforesaid application S. N. 607,333 the azimuth motor 20 and the range motor 32 each operate to search for a new position of balance, 1. e. the new instant flight position, when the position voltages +E7 and E,' energizing the resolver Y, and the voltages +Ex and Ex energizing the resolver X vary according to change in flight position,

It is to be noted that when the coordinates x and y of the flight position are each zero, the pen I9 is at the center of the chart, Fig. 4. This point is assumed to be the location of the radio transmitter T. With the destination point D, Fig. 5, displaced from point T by coordinates x and y, the values of these coordinates are: x'=TD sin 8, and y'=TD cos 6. Therefore as above described in connection with Fig. 4, the values 1: and y may be derived from a resolver energized by a voltage proportional to the distance TD and ad- Justed according to the angle 8.

For this purpose there is provided referring to Fig. 6 a pair of A. C. potentiometers 45 and 46, each winding being suitably contoured in practice for loading so as to produce a linear relationship between the derived voltage and the amount of slider contact displacement for the load represented by potentiometer Ill. The potentiometers are separately energized from a source of reference voltage Eu: through a transformer 41, the secondary of which has a grounded center tap for producing voltages of opposite instant polarity at the respective potentiometer terminals. The slider contacts 48 and, 49 are adjustable simultaneously by means of the TD distance dial 5, Fig. 2, for deriving output voltages representing -TD and +TD respectively. These voltages are used as indicated to-cenergize a sine-cosine potentiometer 50, or alternatively a magnetic resolver such as a one-phase-two-phase synchro rotary transformer (not shown), which can be set to the angle a. In the present instance the sliders ii and 52 are adjusted according to this angle by means of the a dial 4, Fig. 2, for deriving the destination coordinate voltages E1 and Er corresponding respectively to the values TD sin 6 and TD cos 6 above referred to. The angle a is measured between the indicated ground or zero axis of the potentiometer and the slider 5| Reference is now made to the diagram of Fig. '1 in which the instant position of the aircraft is indicated at a point 0' that is off the desired course OD. As shown, the coordinates of point 0' are x and y and those of point D are x and y so that taking the instant position as the reference point the coordinate difference is (x-x') and y-y'). Assuming now that point 0' is on the desired course OD the relationship between these coordinate differences and the correct course angle 0 may be expressed as It is also to be noted, with reference to the geometry of Fig. 7, that the disance Referring again to Fig. 6, voltages are obtained corresponding to the above coordinate difl'erence values by summing the derived instant, and destination coordinate voltages as by means of a pair of summing amplifiers 53 and 54, the amplifier 53 using voltage inputs +Ex and -Ex' for obtaining an output voltage Eli-Ev and the amplifier 54 using input voltages +Ey and E,' for obtaining an output voltage Ey-Ey'. These output voltages are used to energize one set of twophase windings of a synchronous rotary transformer 55 having two-phase stationary and twophase rotary windings, the rotary coils 5i and 51 being adjustable to any desired value of angle 0 with respect to the fixed coils 58 and 59 by means of the 0 dial 3, Fig. 2.

As shown, the stationary cells 58 and 59 are energized by voltages corresponding to Y-Y' and x x' respectively and it can be shown that the voltages induced in the rotary coils for a given orientation of angle 0 correspond to tan-l I X-X I= 31-1 there will be no output voltage on the coil 58 of the rotary transformer. Now, since it and y are fixed constant amounts, having been preset by the TD dial 5, the variables are the coordinate voltages which depend on the aircraft instant position and-which were derived from Fig. 4 as Ex and E. Accordingly if the x and y voltage values representing instant position are held in the correct ratio to make I X X I a y Y then the phase output voltage at coil 58 will be zero and this can be used as an indication that the aircraft is on-course, as shown diagrammatically by Fig. 5. Any deviation of x or y values from the correct relative values will cause a voltage of the aforesaid value to be in duced in the phase winding 58 and this voltage will have an instant polarity and magnitude proportional to the direction and amount of deviation from the correct on-course path respectively.

Accordingly the voltage from phase winding 58 may be impressed on a phase sensitive A. C. meter to simulate the vertical needle of the crosspointer indicator 8 of Fig. 3, or if preferred this voltage may be rectified by a phase sensitive rectifier and used to operate the vertical needle of a standard D. C. cross-pointer indicator. As shown the output terminal of coil 55 is connected through a slip-ring connection 55' to the primary of transformer 6 I, Fig. 6, the other terminal being connected to ground through a slip-ring 88. The secondary of transformer 6| has a grounded center tap and is connected at opposite terminals to the control grids 82 and 83 of a phase sensitive thermionic twin-rectifier 64 the anodes of which are energized by the aforesaid reference voltage Eac- This rectifier operates in well known manner. A D. C. indicating meter 65 is connected across the respective cathodes 58 and 51 so as to be responsive both in sense and in magnitude to the rectified potential. The meter 65 is zero centered in the vertical position shown as in the case of the vertical needle of the cross-pointer meter so that tracking information can be obtained from deviation of the needle in either direction from the zero position in accordance with the preceding description. Elements i6 and 61' are cathode load resistances.

Similarly in accordance with adjustment of the rotary transformer 55 to angle 0, the voltage (x-x') sin 0+(y--y') cos 0 induced in the other phase winding 51 corresponding to the distanceto-go O'D is used to operate a meter simulating the distance meter ill of Fig. 3, or any conventional form of ambiguity meter indicating passage to or from the station. To this end the output terminal of winding 51 is connected through a slip-ring connection 51' to the primary winding 88 of a transformer 68 and the other terminal is connected to one of the slip-rings 88. The secondary winding of. transformer 89 is provided with a grounded center tap and is connected in the manner above described to control grids l8 tndfll of a thermiground through onic phase=sensitive rectifier]! having a .D. C.

meter 13 connected across the cathodes ll and T5. The meter 13 simulates the distance meter Ill of Fig. 3 and therefore adapted to indicate the position of point 0' with respect to the destination D and show whether the simulated flight is approaching the destination or has passed beyond it since the output of winding 51 reverses in phase after the flight has passed through zero at the destination indication.

The output of phase winding 51- may also be used for operating a distance and ambiguity indicator through a more precise servo mechanism of the follow-up type. The "output voltage is connected by conductor 18 to an amplifier ll for controlling a servo operated distance-to-go and ambiguity meter 18. The output of the amplifier energizes the control windings 19 of a two-phase motor ill) of the type illustrated in Fig. 4 and the motor drives a negative velocity feed-back generator 8| and positions through a gear reducer .82 the slider contact 83 of an "answer potentiometer 84. Thederived negative voltage from slider contact 83 is fed byconductor 85 to the amplifier input for balancing the servo when the opposing -answer voltage equals the input distance voltage from the rotary transformer. By means of the automatic balancing servo system above described the meter 18 is positioned to indicate accurately the sense and magnitude of the input system voltage to give both distance and ambiguity information. The velocity feed-back is employed in well known manner to avoid servo oscillation.

The method and means for operating the indicator simulating the RMI (or ADF) indicator I of Fig. 3 will now be described. Referring to Fig. 8 the windings 88 and 81 of a two-phaseone-phase synchronous rotary transformer 88 are energized by voltages Ex-Ex', and EyEy', from the amplifiers 53 and 54 respectively of Fig. 6. The single-phase winding 88 of the transformer secondary is rotatable with respect to the fixed windings 88 and 81 and maybe if desired mechanically coupled to, a servo mechanism designed to rotate the coil 88 toward a position where the voltage induced in the coil is a minimum. Specifically, the output terminal of the coil 8! is connected through a slip-ring connection 98 to the input of a motor amplifier ill, the outputof which energizes the control winding 92 of a two-phase motor 83 that is mechanically coupled as indicated through a gear reducer 94 to the coil 89. The motor 83 also drives a generator 95 for producing a negative velocity feed-back voltage for the input of amplifier ill for servo damping. The servo motor 93 is responsive to the induced voltage (x-x) cos 0'(yy') sin 0' from coil 88. By reason of the fact that the motor is so polarized that it runs in the direction of minimizing this voltage, it will be seen that the servo will come to rest and set itself to the angle 0' which will satisfy the relation In an alternative and simplified arrangement for positioning the coil 91, the servomotor 93 and its associated equipment may be dispensed with and the shaft of coil 89 used directly to position coil 91. In this case the terminals of coil 89 would be energized by the reference voltage Eac for providing sufficient torque to move coil 09 to a stabilized position. Since the bearing angle 6' is without reference to the instant heading of the aircraft and since the RMI indication of meter 1. Fig. 3, is the direction of destination D from the aircraft heading, namely (IV-c), it is necessary to subtract the azimuth of the aircraft heading 0. from the destination bearing Referring again to Fig. 8 this may be accomplished in one form of the invention by means of the differential three phase three phase synchronous rotary transformer 96 having one set of Y-connected windings 91 mechanically connected as indicated at 90 to the servomotor 93 for adjustment to the angle 0' The winding 91 is electrically connected through slip-ring connections 99 to a similar energized through slip-ring connection I06 from the same source of reference A. C. volt-age as the a coil I02 and the coil I06 is mechanically connected at I01 to an indicator I01 for simulating a fixed scale type ADF indicator. The angle (0'a) is read directly between the fixed refer; ence index I01c and the pointer l01b.

The operation of the apparatus of Fig. 8 will be apparent from the above description and it is sufllcient to state that as the u positioned coil I02 changes its orientation, the RMI or ADF positioning coil I00 moves through a corresponding angle in the manner of a synchronou repeater, assuming of course that the angle 0' does not change as in the case where the aircraft executes a "tight circle. When the angular position of winding 91 is changed according to change in angle 0' the angular movement of coil I06 represents the ADF reading which is the difference between the angular movements of windings I01 and I02, 1. e. 0'a as illustrated by Fig. 7.

In the preferred form shown by Fig. 9A, the RMI indicator 1 corresponds to that of Fig. 3 wherein the scale 1a and the pointer 1b are both independently rotatable to represent respectively magnetic compass reading and the magnetic bearing 9 of the destination D, Fig. 7. The scale 1a is indicated as mechanically connected "through a unity ratio gearing 1d to the magnetic compass I2, Fig. 4, and the pointer 1b is connected to the shaft I01 of unit I05, the position of which indicates the angle (0'-a.). Since the scale 19. rotates to repeat the magnetic compass reading, the orientation of this scale with respect to the fixed "lubber line 10 is the magnetic head'- ing of the airplane and the scale reading at the pointer is the magnetic hearing 0' of the destination.

It will therefore be seen from the above description of my invention that a student pilot may practice course tracking in a grounded trainer by setting the same kind of dials to establish his course and observing the same type of instruments as if he were in an actual aircraft. Furthermore it will be apparent that the student may practice holding problems wherein the aircraft shuttles between two given points while awaiting its turn for approaching a busy airport using standard radio compass ADF procedure. This is done by having the instructor set the TD and a dials 5 and I respectively of Fig. 6 to the offset position desired for the compass locator station D with respect to the chart center T and using the apparatus of Fig. 8 for operating and following the RMI or ADF indicator I01 throughout the holding course. Where consecutive holding courses or cross-country tracking are involved and the aircraft advances in turn by course steps the compass locator point D then becomes a new origin point and the computer is set for a new compass loca-tor point.

Also it will be understood that it is within the scope of the present invention as shown by Fig. 9 to duplicate apparatus of .Figs. 6 and 8, including suitable circuits having a throw-over switch I08 for switching the two-phase-two-phase r0- tary transformer 55 of Fig. 6 together with the indicating meters 65, 15 and 18 from one pair of summing amplifiers 53, 54 to another duplicate pair 53', SI for representing the second locator station, in order to simulate the use of two (or more) compass locator stations or destination points D. The duplicate set of summing amplifiers will be energized in the same manner as illustrated in Fig. 6, except that the second locator station will be represented by different coordinate voltages Ex" and E," derived from duplicate TD and 6 controls whereby the outputs of the duplicate amplifiers are (Err-Ex") and (Ey-Ey") respectively.

It will also be apparent that where duplicate sets of apparatus illustrated in Fig. 8 are provided the separate pointers of a dual ADF indicator (or dual RMI) may be operated respectively for obtaining in a well known manner cross-bearings, i. e. a plurality of "fixes" along the course at convenient intervals. Such duplicate apparatus is simply connected to the E1 and Ey output terminals of the circuit of Fig. 4 in parallel with and in the same manner as the apparatus of Figs. 6 and 8. Specifically, the reading for a single station is obtained by the disclosed apparatus in the manner above described. In order to get a concurrent reading for another station, duplicate apparatus corresponding to the radial and distance potentiometers 50, I5 and 40 and the associated summin amplifiers 53 and 54, is connected as indicated to the out-put terminals of the apparatus of Fig. 4. These terminals are energized by voltages E: and E, representing the instant flight position. It will be noted that the duplicate potentiometers provide for off-setting so that the aforesaid instant flight position voltages can be used in combination therewith. The output terminals of the duplicate summing amplifiers are in turn connected as indicated to duplicate apparatus corresponding to Fig. 8 for representing the other station. The radial and distance values for the other station are then set into the duplicate computing apparatus in the same manner as Fig. 6 for obtaining dual ADF indication.

I t will be apparent that where ADF or dual ADF operation is simulated the TD and a values would be set in by the instructor, usually by a duplicate an angle representing summing algebraically the 11 set of dials at the instructor's station, thus simulating a tuned condition of an aircraft radio receiver (or receivers) to the radio station (or stations) in question. Thus, the needle (or needles), MW) of an ADF indicator, Fig. 8, continuously bear on the respective station as the simulated flight proceeds.

Whore DME and ofl-course tracking are simulated, the student sets the TD and 6 dials as in actual practice.

It should be understood that this invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing. from the spirit of the invention.

What is claimed is:

1. In a training system for simulating radio navigation between two points defining a course offset with respect to a radio range reference station, electrical apparatus for computing distance values which comprises means for deriving a pair of voltages representing Cartesian x and y coordinates of instant position of the simulated flight, means for deriving potential according to magnitude of the distance between said station and the destination point, resolving means energized by said distance potential and adjustable through a bearing angle from said station to said destination point for obtaining "voltages representing the Cartesian x and y coordinates of said destination point, means for aforesaid instant position and destination point voltages for the x and y axes respectively for obtaining voltages representing the coordinate difference values, additional ence voltages and adjustable through an angle representing the desired course bearing for obtaining potential representing the magnitude of the distance from instant position to said destination point respectively, and indicating means energized by said last-named potential.

2. In a training system for simulating radio navigation between two points defining a course offset with respect to a radiorange reference station, electrical apparatus for computing course deviation values which comprises means for deriving a pair of voltages representing Cartesian x and y coordinates of instant position of the simulated flight, means for deriving potential according to magnitude of the distance between said station and the destination point, resolving means energized by said distance potential and adjustable through an angle representing a bearins angle from said station to said destination point for obtaining voltages representing the Cartesian x and y coordinates of said destination point, means for summing algebraically the aforesaid instant position and destination point voltages for the x and y axes respectively for obtaining voltages representing the coordinate difference values, additional resolving means energized by said difference voltages and adjustable through an angle representing the desired course bearing for obtaining potential representing the extent of deviation from said course, and indicating means energized by said last-named potential.

3. In a training system for simulating radio navigation between two points defining a course offset with respect to a radio range reference station, electrical apparatus for computing course deviation and distance values which comprises means for deriving a pair of voltages representing Cartesian x and y coordinates of instant resolving means energized by said difirposition of the simulated flight, means for deriving potential according to magnitude of the distance between said station and the desination point, resolving means energized by said distance potential and adjustable through an angle representing a bearing angle from said station to said destination point for obtaining voltages representing the Cartesian x and y coordinates of said destination point, means for summing algebraically the aforesaid instant position and destination point voltages for the x and y axes respectively for obtaining voltages representing the coordinate difference values, additional resolving means energized by said difference voltages and adjustable through an angle representing the desired course bearing for obtaining a pair of voltages representing the extent of deviation from said course and the magnitude of the distance from instant position to said destination point respectively, and a pair of indicating means energized respectively by said last-named pair of voltages.

4. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a. radio range reference station comprising meansfor deriving voltages representing the coordinates ofinstant position of a simulated flight, means initially adjustatle according to the relative position of said station with respect to the destination point for obtaining voltages representing the position coordinates of said destination point, computing means initially adjustable according to the desired flight course bearing from an origin point to said destination point and jointly responsive to said instant position and destination coordinate voltages for obtaining potential representing deviation from said flight course, and indicating means controlled by and in accordance with said last-named potential for indicating the extent of deviation from said course.

5. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a radio range reference station comprising means for deriving voltages representing the coordinates of instant position of a simulated flight, means initially adjustable according to the relative position of said station with respect to the destination point for obtaining voltages representing the position coordinates of said destination point, computing means initially adjustable according to the desired flight course bearing from an origin point to said destination point and jointly respective to said instant position and destination coordinate voltages for obtaining voltages representing deviation from said flight course and the instant distance to said destination point respectively, and indicating means controlled by and in accordance with said last-named voltages for indicating respectively course deviation and the instant distance to destination. v

6. Training apparatus for simulating radio navigation in either direction with respect to a radio range reference station and another point comprising means for deriving potentials representing the coordinates of instant position of a simulated flight, means for obtaining potentials representing the coordinates of said point, computing means initially adjustable according to the desired flight course bearing and jointly responsive to said instant position potentials and said point coordinate potentials for obtaining in turn voltages representing deviation from said flight course and the instant distance to destination respectively, and indicating means controlled by said last-named voltages for indicatms respectively course deviation and the instant distance to destination.

7. Training apparatus for simulating radio navigation with respect to a radio range reference station and another fixed point comprising means for deriving potentials representing the coordinates of instant position or a simulated flight, means initially adjustable according to the distance between said station and said fixed point and to a bearing angle from said station to said point for obtaining potentials representing the coordinates of said point, computing means initially adjustable according to the desired flight course bearing and jointly responsive to said instant position potentials and said point coordinate potentials for obtaining in turn voltages representing deviation from said flight course and the instant distance to destination respectively, and indicating means controlled by said last-named voltages for indicating respectively course deviation and the instant distance to destination.

8. Training apparatus for simulating radio navigation betweentwo points [between two points defining a course ofiset] with respect to a radio range reference station comprising means for representing the compass heading of the aircraft, means for deriving voltages representing coordinates of instant position of a simulated flight, means initially adjustable according to the relative position of said station with respect to the destination point for obtaining voltages representing the position coordinates oi said destination point, servo positioning means operable according to said instant and destinationcoordinate voltages for representing the actual course bearing at said instant flight position, and means adjustable according to the operation of both said course bearing means and compass heading means for positioning indicating means simulating an automatic direction finder.

9. Training apparatus for simulating radio navigation between two points defining a course ofi'set with respect to a radio range reference station comprising means for deriving voltages representing the coordinates of instant position of a simulated fiight, means initially adjustable both according to the distance between said station and the destination point and to a bearing angle from said station to said destination point for obtaining voltages representing the position coordinates of said destination point, means including a voltage resolver initially adjustable according to the desired course bearing and jointly responsive to said instant and destination coordinate voltages for obtaining a course voltage representing deviation from said course and a distance voltage representing the instant distance to said destination point, and course and distance indicating means controlled by and in accordance with said course and distance voltages respectively.

10. Training apparatus for simulating radio navigation between two points [between two points defining a course ofi'set] with respect to a radio range reference station comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight, means for obtaining voltages representing the position coordinates of the destination point,

. means controlled according to said instant and destination coordinate voltages for representing the actual course bearing for instant flight position and means adjustable according to the operation of both said course bearing and compass heading means for simulating an automatic direction finder.

11. Training apparatus for simulating radio navigation between two points [between two points defining a course offset] with respect to a radio range reference station comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight, means for obtaining voltages representing the position coordinates of the destination point. means controlled according to said instant and destination coordinate voltages for representing the actual course bearing for instant flight position and means including a synchronous resolver responsive to said last-named means and adjustable according to said actual course bearing and energized by potential derived according to the aforesaid compass heading for positioning an indicator simulating an automatic direction finder.

12. Training apparatus for simulating radio navigation between two points [between two points defining a course offset] with respect to a radio range reference station comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight, means for obtaining voltages representing the position coordinates of the destination point, means controlled according to said instant and destination coordinate voltages for representing the actual course bearing for instant flight position and means including a rotatable scale element adjustable with respect to a fixed index according to the operation of the aforesaid compass heading means and a pointer element jointly responsive to said course bearing means and said compass heading means and adjustable with respect to said scale for simulating automatic direction finding equipment.

13. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a radio range reference station comprising electrical means for deriving voltages representing the instant position coordinates of the simulated flight, means for deriving potential corresponding in magnitude to the distance between said station and the destination point, resolving means energized by said distance potential and adjustable according to a bearing angle from said station to said destination point for obtaining potential representing the position coordinates of said destination point, means for summing said instant and destination coordinate potential for obtaining potential representing coordinate diiference values, resolving means initially adjustable according to the desired flight course bearing and energized by said coordinate difierence potential for obtaining a pair of potentials representing deviation from said flight course and the instant distance to said destination point respectively, and course and distance indicating means controlled by and in accordance with said last-named potentials respectively.

14. Training apparatus for simulating radio navigation between two points [between two points defining a course ofiset] with respect to a radio range reference station comprising means for deriving voltages representing the coordinates of instant position of a simulated flight, means initially adjustable according to the distance bethe corresponding station with new tween said station and the destination point and to a bearing angle from said station to said destination point for obtaining voltages representin the position coordinates of said destination point, means for algebraically summing said instant position and destination coordinate voltages for obtaining voltages representing coordinate difference values, inductive means energized by the aforesaid difference voltages and including relatively movable primary and secondary windings and means responsive secondary'w ifiding for adjusting said windings to a null voltage position, said position as referred to a reference position representing the actual course bearing, means adjustable according to the trainer compass heading for deriving a voltage representing compass heading, an inductive device having a primary winding energized by said compass voltage and a secondary winding, one of saidwindings being adjustable by said null positioning means according to the aforesaid actual course bearing, and means responsive to the voltage induced in said secondary winding representing an automatic direction finder indicator.

[15. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a plurality of radio range reference stations comprising means for representing the compass heading of the aircraft, means for deriving voltages representing coordinants of instant position of a simulated flight, data-setting means, one for each station initially adjustable according to the relative position of respect to the destination point for obtaining respective voltages representing position coordinants of said destination point, means associated with each data-setting means and said instant position means for obtaining respective voltages representing the coordinant differences of said instant and destination points, and a plurality of voltage resolving means each energized by a respective set of coordinate difference voltages and adjustable according to the aforesaid compass heading for positioning respective indicating means so as to represent dual automatic direction finding apparatus] [16. Training apparatus for simulating radio navigation between two points defining a course offset with respect to first and second radio range reference stations comprising means for representing the compass heading of the aircraft, means for deriving voltages representing coordinants of instant position of asimulated flight with respect to one of said stations, means initially adjustable according to the relative position of a first reference station with respect to the destination point for obtaining voltages representing position coordinants of said destination point, means energized by said instant and destination voltages for obtaining voltages representing the coordinant differences of said instant position and destination points, voltage resolving means energized by the aforesaid coordinant difference voltages and adjustable according to the aforesaid compass heading for positioning indicating means so as to represent automatic direction finding apparauts with respect tosaid first reference station, means also initially adjustable according to the relative position of a second reference station with respect to said destination point for obtaining additionalvoltages representing position coordinates of said destina- .tion point, means energized by said instant and to voltage induced in said-- ordinate additional voltages for obtaining voltages representing the coordinate differences of said instant position and destination points, voltage resolving means energized by the last-named coordinate difference voltages and adjustable according to the aforesaid compass heading fon positioning additional indicating means automatic direction finding apparatus with re, spect to said second reference station, thereby simulating dual automatic direction finding equipment] 1'7. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a radio range reference station comprising means for deriving voltages representing the coordinates of instant position of a simulated fiight, means initially adjustable according to the relative position of said station with respect to the destination point for obtaining voltages representing the position coordinates of said destination poin computing means initially adjustable according to the desired flight course hearing from an origin point to said destination point and jointly responsive to said instant position and destination coordinate voltages for obtaining potential representing the instant distance to said destination point respectively, and indicating means controlled by and in accordance with said last-named potential for indicating the instant distance to destination.

18. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a radio range reference station comprising electrical means for deriving voltages representing the instant position coordinates of the simulated flight, means for obtaining voltages representing the position coordinates of saiddestination point, means for summing said instant and destination coordinate voltages for obtaining potentials representing codifference values, and resolving means initially adjustable according to the desired flight course bearing and energized by said coordinate difference potentials for obtaining potentials representing deviation from said flight course, and indicating means controlled by and in accordance with said last-named potential.

19. Training apparatus for simulating radio navigation between two points defining a course offset with respect to a radio range reference station comprising means for deriving control quantities representing the coordinates of instant position of a simulated flight, means initially adjustable according to the relative position of said station with respect to the destination point for obtaining control quantities representing the position coordinates of said destination point, computing means initially adjustable according to the desired flight course bearing from an origin point to said destination point and jointly responsive to said instant position and destination coordinate control quantities for obtaining a resultant control quantity representing deviation from said flight course, and indicating means controlled by and in accordance with said last-named resultant control quantity for indicating the extent of deviation from said course.

20. Training apparatus for simulating radio navigation in either direction with respect to a radio range reference station and another point comprising means for deriving control quantities representing the coordinates of instant posi-' tion of a simulated flight, means for obtaining control quantities representing the coordinates so as to represent of said point, computing means initially adjustable according to the desired flight course bearing and jointly responsive to said instant position control quantities and said point coordinate control quantities for obtaining in turn control quantities representing deviation from said flight course and the instant distance to destination respectively, and indicating means controlled by said last-named control quantities for indicating respectively course deviationand the instant distance to destination.

21. Training apparatus for simulating radio navigation between two' points [between two points defining a course ofiset] with respect to a radio range reference station comprising means for representing the compass heading of the aircraft, means for deriving control quantities representing the coordinates of instant position of a simulated flight, means for obtaining control quantities representing the position coordinates of the destination point, means controlled according to said instant and destination coordinate control quantities for representing the actual course bearing for instant flight position and means adjustable according to the operation of both said course bearing and compass heading means for simulating an automatic direction tinder.

22. Apparatus for simulating dual ADF radio navigation with respect to two radio stations for establishing a flu: for the instant fight position comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinants of the instant position of the simulated flight with respect to a fixed reference point, flrst data-setting means" initially adjustable by an instructor according to the relative position of one of said stations with respect to said reference point for obtaining voltages representing the coordinants of said station with respect to said reference point, second data-setting means initially adjustable by the instructor according to the relative position of the other station with respect to said reference point for obtaining voltages representing the coordinants of said other station with respect to said reference point, a computing means operatively related to each of said data-setting means and adjustable according to the orientation of said compass heading means for determining the bearing from said flight position to the respective radio station, each computing means being responsive to the algebraic sum of said instant position voltages and the respective station voltages, and respective indicating means operable by said computing means for simultaneously indicating said station bearings thereby to simulate dual ADF apparatus.

23. Apparatus for simulating dual ADF radio navigation with respect to two radio stations for establishing a fin: for the instant flight position comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinants of the instant position of the simulated flight with respect to a fixed reference point, first data-setting means including potentiometer means initially adjustable by an instructor according to the relative position of one of said stations with respect to said reference point for obtaining voltages representing the coordinants of said station with respect to said reference point, second data-setting means including potentiometer means initially adjustable by the instructor according to the relative position of the other station with respect to said reference point for obtaining voltages representing the coordinants of said other station with respect to said reference point, a computing means operatively related to each of said data-setting means, each computing means including voltage resolving means responsive to the algebraic sum of said instant position voltages and the respective station voltages and adjustable in accordance with the orientation of said compass heading means for determining the bearing from said flight position to the respective radio station, and respective indicating means operable by said computing means for simultaneously indicating said station bearings thereby to simulate dual ADF apparatus.

24. Training apparatus for simulating radio navigation by direction finding equipment comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight with respect to a station or reference point, means for obtaining voltages representing the position coordinates of a compass locator station with respect to said reference point, means controlled according to said instant and locator station coordinate voltages for representing the bearing of said locator station from said instant flight position and means adjustable according to the operation of both said bearing and compass heading means for positioning indicating means simulating an automatic direction finder.

25. Training apparatus for simulating radio navigation by direction finding equipment comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight with respect to astation or reference point, means including data-setting means for obtaining voltages representing the position coordinates of a compass locator station with respect to said reference point means for algebraically summing said instant and locator station coordinate voltages, means responsive to said summing means for representing the bearing of said locator station from said instant flight position and means adjustable according to the operation of both said bearing and compass heading means for positioning indicating means simulating an automatic direction flnder.

26. Training apparatus for simulating radio navigation by direction finding equipment comprising means for representing the compass heading of the aircraft, means for deriving voltages representing the coordinates of instant position of a simulated flight with respect to a station or reference point, means including data setting means initially adjustable by an instructor for obtaining voltages representing the position coordinates of a compass locator station with respect to said reference point, means for algebraically summing said instant and locator station coordinate voltages, and voltage resolving means jointly responsive to said summing means and said compass heading means for positioning indicating means simulating an automatic direction finder with respect to said instant flight position and compass locator station.

RICHARD CARL DEHMEL.

(References on following page) REFERENCES CITED The following references are or record in the file of this patent or the original patent:

UNITED STATES PATENTS Number Name Date Pottenger Feb. 9, 1937 Libman Nov. 22, 1938 Koster July 4, 1939 Noxon Jan. 19, 1943 Cone June 15, 1943 Lyman Apr. 18, 1944 Dehmel Jan. 2, 1945 Number 20 Name Date Grow Nov. 20, 1945 Kittridge Mar. 19, 1946 Doyle May 7. 1946 Holden Sept. 3, 1946 Lewis Sept. 3, 1946 Lovell Sept. 24, 1946 Alexanderson Mar. 11, 1947 Sanders Dec. 16, 1947 Kittridge Apr. 6. 1948 Darlington Apr. 13, 1948 Muller Sept. 7, 1948 Field Mar. 1, 1949

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