US2410097A - Glide attachment for bomb sights - Google Patents

Description

at; 29, 1946. B, HANSON 2,410,067

- SUBMARINE SIGNALING Filed Sept 23, 1958 4 /4 ,0 i 6 g L M 7L A rL n s L r\ V FREQUENCY OF Rc| z|v|Nc SYSTEM HAS TRANSMITTED 5 6- 2 FREQUENCY BAND LYING NAL SWEPTFROM I WHOLLY WITHIN TRANS- POINT- OUTSIDE OF i, I MITTED FREQUENCY PASS BAND OF BANDsHARPLY TUNED. RECEIVER SYSTEM 7 TO ZERO HETRODYNE /2 BEAT.

JRA smTTED FREQUENCY VAREES 9 PROGRESSIVELY OVER A PREDETER- MINED FREQUENCY BAND.

0- 1 HETRODYNE RECEIVER AMPLIFER fi JE .5- mm BERTRAM m. HARRISON 1946. F. w. MORGENTHALUER' ETAL Q 2.41

GLIDE ATTACHMENT FOR- BOMB SIGHTS Filed Jan. 17, 1942 5 Sheets-Shet. 2

TO ALTITUDE CONTROL CONSTANT SPEED l lL|.|

Z 9 0 m g E* g g l U Q .J 2 :2 LL i- INVENTORS, o8 FREDERICK W- MORGENTHALER, m and JOHN s GARWOOD;

m 0 BY 58 I heir A ORN 1946. F. w. MORGENTHALER ETAL 2,410,097

GLIDE ATTACHMENT FOR BOMB SIGHTS 3 Filed Jan. 17, 1942 v s Sheets-Sheet s minnuqn mvsm-ons. FREDERICK w. MORGENTHALER,

and JOHN s. GARWOOD,

Patented Got. 29, 1946 j'uNi'i'so s'm'ras Paras-racemes Frederick W. Morgenthaler, Brooklyn, and John S. Garwood, New York, N. Y., assignors to Sperry Gyroscope Company, ,Inc., Brooklyn, N. Y., accrporation of New York Application January 17, 1942 Serial No. 427,162

Claims.

The present invention is concerned with a glide attachment for bombsights. The present case is concerned with a modification and improvement of the device shown in copending application for Automatic climb and glide control for aircraft, Serial No. 269,838, filed April 25, 1939 in the names of C. A. Frische and G. N. Hanson.

In prior, application Serial No. 387,574, for Bombzsights, filed April 9, 1941 in the names of H. C. Van Auken and F. N, Esher, there is dis closedpa bomb sight and automatic pilotsystem whereby .the bombardier is enabled to control the course of the craft by means of the automatic pilot during bombing operations. However, the device of the above application is restricted to use during level flight, and is incapable of effective use during other than level flight operations. Since during level flight the bombing craft is especially susceptible to attack from antiaircraft equipment or other aircraft, it is desirable to permit bombing operations during other than level flight conditions, such as during climbing or gliding.

, According to the present invention, an attachment is provided for such a system as disclosed in the above mentioned application Serial No. 387,574, whereby'theautomatic pilot is controlled in such a manner that the craft is caused to assume a constant rate of climb or'rate of glide, and

at the same time, the settings of the bomb sight, especially those for time of fall and for trail, are automatically corrected so that accurate sighting and bombing may be automatically maintained during the climb or glide.

Accordingly, it-is an object of th present invention to provide an improved glide attachment for bomb sight and automatic pilot systems whereby effective bombing may be performed during climbing or gliding of the craft.

It is still another object of the present invention to provide improved control means for bomb sight controls which will permit efiective' change in altitude of an 2 will become apparent as the description proceeds.

In the drawings,

Fig, 1 shows on form of the present invention employing a manual adjustment of the bomb sight correction controls.

Fig. 2 shows a modification of the system of Fig. 1 using automatic adjustments of the bombsight controls.

.Fig. 3 shows another modification of the systems of Figs. 1 and 2.

Fig. 4 shows a perspective schematic View of the solenoid ratchet motor device used with the system of Fig. 3. I

Fig. 5 shows a wiring diagram of the system of Fig. 3.

In Fig, 1, there is shown. a glide or climb attachment especially useful with a bomb sight'of the type shown in application'Serial No. 387,574. It has been determined that during constant rate of change of altitude, as in constant rate of climb or glide, the required time of fall and trail settings of the bomb sight vary substantially proportionally to the instantaneous altitude, for quite wide variations of altitude. The proportionality factor depends on the altitude at which climb or glide starts, and, in the case of trail, upon the air speed.

The device of Fig. 1 provides means for continuously correcting the trail and time of fall controls of the bomb sight in accordance with altitude. Here, a common control is used for producing climb or glide and for simultaneously adjusting the control mechanism to vary the bomb sight controls at a rate proportional to rate of change of altitude, whereby the settings of these controls are synchronized with the altitude of the craft.

Thus, referring to Fig. 1, altitude rate control knob 69 translationally positions a ball carriage H of a variable speed drive 61, as by means of a pinion l3 and a rack 75. The drive disc of variable speed 6'! drive is driven at constant speed from a constant speed motor 63 and, as a result, the driven cylinder 11 is rotated at a speed dependent upon the position of ball carriage H and altitude rate control 69. Cylinder 71 is connected to a shaft 19 and drives an altitude control shaft 83, as by gears 8|. Shaft 83 is connected to any suitable type of altitude-controlling automatic pilot to actuate the altitude setting thereof, and thereby directly controls the altitude of the craft. A suitable type of aircraftaltitude control is shown in copending application Serial No. 429,754 for Aircraft altitude control, filed February 6, 1942 1 in the names of C. A. Frische and G. N. Hanson.

The rate of climb or glide may be indicated on altitude rate dial I2 geared to altitude rate control 69 and cooperating with a fixed index I4.

It will be clear that the angular displacement of shaft 83 from a predetermined datum setting will be proportional to the instantaneous altitude of the craft, since shaft 83 is directly connected to the craft altitude control. Also, the speed of rotation of shaft 83 (and of shaft I9 connected thereto) is proportional to the rate of change of altitude, that is, to the rate of climb or glide. This shaft 19 is connected to drive disc 85 of another variable speed drive unit 81 having a ball carriage 89 and a driven cylinder 9|. The ball carriage 89 may be positioned from a time of fall correction knob 93 as by way of pinion 95' and rack 91. A time of fall correction indicator scale 93 cooperating with an index IIII is also driven from time of fall correction knob 93 as by way of gear I03.

It will thus be clear that the speed of rotation of output shaft I35 of variable speed drive 3'. will be proportional to the setting of altituderate control 39, the proportionality factor depending on the setting of knob 93. This output shaft IE5 is connected to the rotor of a remote position transmitter I87, which may be of any suitable type, such as the conventional selsyn type, being energized from a suitable source of alternating current 3? and having its output connected to a, cable I133. Cable I89 leads through a suitable control switch (not shown) to a corresponding remote position receiver or repeater which directly positions the usual time of fall setting control of the bombsight, such as shown in the prior application Serial No. 387,574. If necessary, any conventional type of servo mechanism or torque, amplifier may be inserted between the transmitter It] and its receiver.

In this way, the time of fall setting of the bombsight is continuously changed at a rate proportional to the speed of control shaft I65 and will therefore be continuously varied at a rate proportional to the rate of change of altitude and to the setting of time of fall correction control 93. The setting of control 33 as indicated on scale 99 is obtained by the operator from a suitable chart and for certain set of conditions may be once set and left unchanged. In this way, during change of altitude of the craft, the time of fall setting of the bombsight is continuously corrected as the altitude changes and is thus continuously kept at the proper setting for accurate bombing.

A further correction required on the bombsight during climbing or gliding is that for trail. Here again, for a particular airspeed and over a fairly wide range of change of altitude, it has been determined that the trail setting is substantially proportional to the altitude. Hence, a similar type of control is provided for the trail setting control of the bombsight, namely, a variable speed drive I I I whose disc I I3 is driven from the output shaft I9 of variable speed drive 3'! and hence proportional to altitude rate. The ball carriage I I5 of variable speed drive I I I is actuated by trail correction knob II! and the driven cylinder Ilqv of variable speed drive III acts to drive a shaft I2I connected to the rotor of a remote position transmitter I23 similar to transmitter IIll, whose output cable I25 is connected through a suitable control switch (not shown) and amplifiers, if desired, to a similar remote position repeater or receiver connected to drive the trail setting control in the bombsight. A suitable trail correction indicator I21 and an index I29 are also provided.

In this manner, as the craft changes altitude, the trail and time of fall bombsight, controls are continuously maintained in correspondence with the position of the craft, and accurate bombing may be effected during the entire maneuver.

In practice, the following procedure has been found desirable: When the operator has determined that he wishes to perform glide or climb bombing, he will open the control switches connecting the position transmitters I3! and I23 to their respective repeaters. Then he positions time of fall correction knob 33 and trail correction knob II? to the setting corresponding to the particular altitude and air speed at which he intends to start his operations, these settings being determined from suitable charts. Also, the bombsight controls are set to the positions corresponding to this altitude and air speed. Then, by adjusting altitude rate knob 69, the aircraft is caused to start its climb and glide, thereby passing through the pre-selected altitude, at which time, the glide correction mechanism is rendered effective to automatically control the bombsight, by closing the switches connected to the output of the position transmitters. Thereafter the bombsight controls are automatically actuated, as has been described.

Fig. 2 shows a modification of Fig. 1 adapted for complete automatic control Similar elements are given similar reference numerals. Thus the manual time of fall and trail correction knobs 93 and II! have been eliminated, and instead the time of fall variable speed drive 81 now has its ball carriage 39 directly actuated in accordance with altitude as by means of cam I3I driven by shaft I33, gears I35, shaft I31 and gears 39 from shaft I9, which, as was shown above, is'rotated proportionally to altitude.

Cam I 3| is so designed as to insert into the 40 motion of ball carriage 81 and the rotation of shaft I35 the proper proportionality factors as a function of the altitude of craft. This method is somewhat more accurate than that shown in Fig. 1, since it allows for varying proportionality factors while in Fig. 1 the factor was assumed constant.

In a similar way, ball carriage H5 of trail variable speed drive I II is actuated by the follower II4 of a three-dimensional cam I43 which is axially translated inaccordance with altitude, as by way of shaft 19, gears I39, shaft I31, gears I35, shaft I33, pinion I45 and rack- I41. Cam I43 is also rotated as by gear I 33 in accordance with airspeed, as by shaft I5I which may be connected to an airspeed indicator or follow-up mechanism of any suitable type. Cam I l-3 is so designed that the motion of its follower I I4 is proportional to the proper trail proportionality factor to be inserted into variable speed drive I I I at each value of airspeed and altitude.

In this manner, the output rotation of shaft IZI is kept accurately in correspondence with the required setting of the trail control of the bombsight, which it actuates by means of transmitter I23 and its repeater, as the altitude and/or airspeed changes, and hence the system is entirely automatic.

'In operating the device of Fig. 2, the system is disconnected from the bombsight as by opening the control switches in the output circuits of the position transmitters I31 and I23. Then the trail and time of fall settings of the bombsight are adjusted to correspond to a suitable preselected value of altitude and to the actual airspeed of the craft. Then the altitude rate control 69 is actuated to introduce asuitable rate of change of altitude; At the instant that the craft passes through the predetermined value of altitude as evidenced by a suitable altimeter indicator, the vcontrol switches are closed and the system thereafter is automatically'actuated as described above. Figs. 3 to 5 show a further embodiment of the invention; Thus, referring toFig. 3, altitude rate control 69 is connected to shaft 19. An altitude rate indicator I2 cooperates with an index 14 to and is driven by a gear 16 to indicate the setting of altitude rate control knob 69.- Connected to shaft 19is a connecting member I6I which is thereby'rotated with respect to a fixed contact bearing disc I63. Disc I63 is shown as carrying a number of contacts I65 illustrated as being ten in number distributed over a semi-circle. The function of this contact and connector arrangement will be more fully described later.

Control 69 and shaft 19 are adapted to bev rotated in steps as defined by a star-wheel 239 fastened to shaft 19 and cooperating with a springdriven ball detent 249. For each step, member I6I connects to one more or'one less of the contacts I65. Also fastened to shaft 19 is a cam 246 which operates two switches 245, 241 as will be described below.

Fixed to shaft 19 is a pinion 13 actuating a rack and thereby translating ball carriage 1! of the variable speed drive 61, whose disc 65 is driven from constant speed motor 93 by means of gearing I61, shaft I69 and worm and worm wheel arrangement I1I.' The cylinder 11 of variable speed drive 61 is connected directly to shaft 83 and serves to actuate the. same type of climb and glide control aswas explained with respect to Figs. 1 and 2.

Constant speed motor 63 also drives disc II3 of trail variable speed drive II I by means of worm and worm wheel arrangement I13 and gearing I61. The speed of rotation of the driven cylinder II9 of this drive III- is determined by the setting of trail correction control II1 operating through shaft II8, pinion I29 and rack I22 to displace the usual ball carriage I I5. Cylinder I I9 drives a contact arm I15 which thereby continuously wipes across a plurality of fixed contacts such'as E11, mounted in a fixed insulating plate I19. Contacts I11 are the same in number as contacts I65 and their function will be described more particularly with relation to Figs. 4 and 5. In a similar manner, time of fall variable speed drive'91 is driven from constant speed motor '63 by way of gearing I61, shaft I69 and worm and worm wheel arrangement I8I. A similar contact and wiping contactor arrangement I83, I85 and I81 is provided driven by the output of variable speed drive 81 under the control of time of fall correction knob 93 acting in the same manner as the trail correction just described.

Rotating contactor devices I18 and I84 in cooperation with device I64 are each adapted to produce periodic impulses whose number per unit time depends upon the setting of the respective controls 93 and H1 and upon the setting of the control 69. These impulses, in the manner to be presently described, serve to continuously reposition the trail and time of fall settings of the bombsight, and thereby maintain these settings in correspondence with the altitude of thecraft during changes of altitude.

Fig. 4 shows the solenoid-actuated operating mechanism for changing thesetting of the bombs ht trail q ll m xactl s mi a ech nism ,operatesthe time of. fall control; Thus, shaft,l9I represents the shaft of the trail control of-the bombsight. Connected to this shaft is the attachment shownin Fig. 4. Normally, in the absence ofthis attachment, shaft I9I would be controlled by a knob such as I93 cooperating with a scale I95 whereby the control shaft I9I may be manually set to a predetere mined setting corresponding to desired trail as evidenced by the position of dial I95. When the present glide and climb attachment is in use, knob I93 is removed. The device shown in Fig. 4 is then attached at one end to shaft I9I and at the other end to knob I93, and thereby, as will be clear from the following description, shaft I9I may either be actuated manually from knob I93 or automatically by the attachment.

Thus, an operating shaft I 91 is attached at one end to the control shaft I9I and at the other end to knob I93 and dial I95. Operating shaft I91 carries a two-way ratchetwheel I99 fixed thereto. Rotatably supported, on shaft I91 are a pair of arms 29I and 293, each carrying apawl 295 and 291, respectively, pivotally connected thereto as at pivots 299 and 2I I.

Fixed to the casing of the bombsight are a pair of solenoid windings 2I3 and H5 having a com mon plunger 2I1, which is adapted to be moved to the left when solenoid 2I3 is energized or to the right when solenoid 2 I 5 is energized. Plunger 2I1 carries a pin 2I9 extending transversely thereof and positioned between pawls 295. and 291. Arms 29I and 293 are urged together byia spring 22I and pawls 295 and 291 are urged away from ratchet wheel II9 by means of springs 223 and 225 connecting them to the arms 29% and 295, respectively. In this manner, pawls 295 and 291 are maintained in contact with pin 2 I 9 when centralized.

Upon energization, for example, of solenoid 2 l3, pin 2I9 moves to the left. Springs 223 and 225 are made weaker than spring 22I, and stops 221 and 229 prevent arms 29I and 293 from proceeding to the right and left, respectively. In this way, when pin 2I9 moves to the left, the first action ensuing is the pivoting of pawl 295 about ivot 299, whereby pawl 295 is caused to engage ratchet I99. Upon obstruction of the movement of pawl 295 by ratchet I99, further movement of pin 2I9 causes the rotation of arm 29I tothe left carrying with it ratchet wheel I99 and thereby rotating shaft I'9I by a predetermined fixed increment.

It will be clear that energization of the other solenoid 2I5 causing motion of pin 2I9 to the right will cause anopposite incremental rotation of control shaft I9I in the same manner as just described. Hence, eachtime a solenoid is energized, control shaft I9I is rotated by a fixed amount.

Referring to Fig. 5, there is shown a schematic wiring diagram of the entire system. Thus, each of the contacts I65 of contactor plate I63 is connected to a respective one of contacts I11 and contacts I of contactor plates I19 and I83, respectively, as by way of cables 23I and 233. Connecting member I6 I is connected to one terminal of abattery 235 whose other terminal is grounded as at 231. Member IBI" is so'arranged on shaft 19 that, with altitude rate control 69 at its zero position, member I6I does not contact any of the contacts I65. Each step of rotation of shaft 19 changes the number of contacts I65 connected to member I6Ijby one. I

Accordingly, in this zero position, it will be clear that none of the contacts I65, IT! or I85 are energized from battery 23I. If altitude rate control 69 is moved to the right by a fixed increment determined by the detent mechanism 239 of Fig. 3, say, one notch in a clockwise direction, it will be clear that member IBI will now connect battery 235 to the first one of the contacts I55 and accordingly one contact IT! and one contact I85 will be energized. If member I6I is moved two notches clockwise, two contacts I65 will be energized from battery 235 and hence two contacts I11 and two contacts I85 will be energized, etc. Hence, for each discrete value of altitude rate set in by way of control 59 a corresponding number of contacts I65, I17 and I85 will be energized from battery'235.

In a similar manner, if instead of climb, to which clockwise rotation of control 69 may correspond, glide is ordered, control 69 will be rotated counter-clockwise and in the same manner for each value of glide rate a corresponding number of contacts I17 and I85 will be energized from battery 235.

Moving arms I15 and I8! continuously rotate at the speeds corresponding to the settings of trial control II I and time of fall correction 93, and a voltage pulse is produced each time one of these arms passes over an energized contact. Accordingly, the number of voltage impulses produced per unit time in the output wires 24] and 243 connected to these arms I75 and I8! will be proportional, firstly, to the setting of altitude rate control 69 and secondly, to the setting of the respective controls 93 or I H.

The outputs of contacting devices I84 and I18 as appearing on wires 24! and 243 are connected to cam-operated switches 245 and 24'! through a double-pole, single-throw control switch 242. Each of these switches 245, 241 is a single-pole double-throw switch and serves, as will be described, to connect the proper one of solenoids 2 I 3 and 2I5 to the voltage pulses produced, corresponding to whether'climb or glide is taking place.

Thus, switches 245, 241 are actuated by a cam 246 fixed to altitude rate control shaft I0. With zero altitude rate setting, central members 248, 248' are completely disconnected from their respective outer contacts 249, 25I and 249', 25I'. With one sense of altitude rate, such as climb, set in, contacts 248, 248 are connected to 249, 249', respectively. With a glide setting, contacts 248, 243 are connected to 25I, 25!, respectively.

Solenoids 2I3, 2E5 of the time of fall solenoid motor shown in Fig. 4 each have one terminal grounded as at 231, the other terminals being connected to switch terminals 25!, 249, respectively. Similarly, trail solenoids 2I3', 2E5 have one terminal connected to ground at 237 and the other terminals connected to switch contacts 25 I 249', respectively.

For each impulse delivered from the inpulsing devices I18 or IE4, the corresponding bombsight control will be moved by a fixed-amount, thedirection of adjustment being determined by switches 245, 241 and hence by the sense of altitude rate. In this manner, both trail and time of fall settings of the bombsight will be adjusted in the direction corresponding to climb or glide and at a rate corresponding to the number of impulses produced in these contact devices per unit time. As has been shown, this number of impulses per unit time is proportional both'to the altitude rate as set into contact device I63 and to the setting of trail and time of fall correction knobs III and 93. The latter settings are chosen properly taken into account.

The operating procedure of this device of Figs. 3 to 5 is as follows: With switch 242 open, the operator will set the time of fall and trail settings of the bombsight corresponding, for example, to shaft I9I, at the proper setting corresponding to an altitude slightly lower than his present altitude if he intends to glide, or slightly higher if he intends to climb. At the same time, the settings of controls 93 and II! are made, as determined from proper tables which show the proper rate of change of trail and of time of fall for the particular altitude and wind speed encountered at the beginning of the glide or climb.

With switch 242 still open, so that solenoid motors are inoperative, the operator will commence his climb or glide by setting in the desired rate of climb or glide by means of altitude rate control 69. At the instant that the craft passes through the altitude for which the settings have been made, as indicated by any suitable altimeter, switch 242 is closed, whereupon the craft proceeds to change its altitude at the rate determined by the setting of the control 69, and the trail and time of fall settings of the bombsight are continuously adjusted to maintain them in proper relationship as the craft changes altitude.

Accordingly, the time of fall and trail settings of the bombsight are maintained at their proper 'Values so that as soon as the target is centered in the sight and release of the bomb occurs the proper corrections for accurate bombing will be included in the bombsight settings.

It will be clear that the device of Figs. 3 to 5 is an approximation only to the proper synchronism of the trail and time of fall settings withthe altitude change, since it occurs in incremental steps. However, these increments are made very small, such as of the order of one hundredth of a second perincrement of time of fall, so that a good approximation to continuous resetting of the bombsight controls, such as may be obtained by the device of Fig. 2, is obtained. In order to improve the action, it is desirable that the impulses produced'should be as equally spaced as possible. This means that the connections between contacts M55 and contacts ill and I should be designed to provide substantially equal spacing among the'energized contacts for any setting of contact member ISL For example, if ten contacts are used as illustrated, and supposing that contacts I55 are numbered from one to ten in a clockwise direction beginning at the left, and contacts I'll and I85are similarly numbered, a suitable set of connections may be as shown on the following table, wherein the first column denotes the number of a contact I65 connected to a contact I Ti or I 85 whose number is given in the second column. This table is:

In this manner, when contact member I6I is rotated inone position clockwise, only contact #1 of contacts IT! or [85 will be energized. When two contacts I65 are energized by member 16!, contacts #1 and #5 of IT! or I85 will be energized, and, it will be seen that these are approximately equally spaced. If three contacts are energized, these will be #1, #5 and #9, again approximately equally spaced. Four contacts will be #1, #5, #9 and #3, and live contacts will be #1, #5, #9, #3 and #7, again in each case approximately equally spaced.

If contact member l6l is rotated in the opposite direction from its zero position, for one contact energized, contact will be energized. For two contacts, #10 and #6 will be energized. For three contacts, #10, #6 and #2 will be energized. Four contacts will be #10, #6, #2 and #8. Five contacts, #10, #6, #2, #8 and #4. Accordingly, it will be clear that, for either direction of rotation and for any number of contacts energized, approximately equal time intervals will be produced by the pulses. a

It will be evident that the invention is not restricted to the use of ten contacts, with respect to which it has been illustrated, but any suitable number of contacts and any suitable connection of contacts #65 with contacts ll! or contacts I85 may be used.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An aircraft provided with an automatic pilot having an altitude control, a bombsight carried by the aircraft having control means, means for actuating the altitude control to change the altitude of the aircraft, and means responsive to the operation of the actuating means for continuously adjusting the control means of the bombsight to compensate for the effect of changing altitude.

2. In an aircraft carrying a bombsight having at least one control, altitude control means for the aircraft, a variable speed device having its output connected to said altitude control to change the altitude of the aircraft at a constant rate, and means controlled by the variable speed drive for adjusting said bombsight control at a rate proportional to said altitude rate, whereby said bombsight control is compensated for the effect of changing altitude.

3. In an aircraft carrying a bombsight having at least one control, altitude control means for the aircraft, a variable speed device having its output connected to said altitude control to change the altitude of the aircraft at a constant rate, means controlled by the variable speed drive for adjusting said bombsight control at a rate proportional to said changing altitude rate, whereby said bombsight control is compensated for the effect of changing altitude, and means for adjusting the last mentioned means to vary the proportionality between said altitude rate and the rate at which the bombsight is adjusted.

4. In an aircraft having altitude control means, a bombsight carried thereby having control means, a variable speed device having its output connected to said altitude control means to change the altitude of the aircraft at a constant rate, and means controlled by the variable speed drive for adjusting said bombsight control means at a rate proportional to said altitude rate, whereby said bombsight control means is compensated for the effect of changing altitude, wherein the means controlled by the variable speed drive includes a disc, ball and cylinder type of variable speed drive, means for driving said disc by the output of the first variable speed drive, means for actuating said bombsight control means by said cylinder, and means for adjustably positioning said ball to thereby change the proportionality between the bombsight control means adjustment rate and said altitude rate.

5. In an aircraft having altitude control means, a bombsight carried thereby having at least one control, a variable speed device having its output connected to said altitude control to change the altitude of the aircraft at a constant rate, and means controlled by the variable speed drive for adjusting said bombsight control at a rate proportional to said altitude rate, whereby said bombsight control is compensated for the effect of changing altitude, wherein said last means comprises means for generating impulses at a rate proportional to said altitude rate and a motor controlled by said impulses connected to actuate said bombsight control.

FREDERICK W. MORGENTHALER. JO RW O

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