US2415967A - Gun turret - Google Patents

Description

Feb. 18, 1947. a. w. PONTIYUS, an 2,415, 5

I GUN TURRET mm m. 4, 1942 1: sums-sum 2 BY 6:020: W. Para-nus Feb. 18, 1947.. G, w, Pom' 3., 2,415,967

mm mm- Filed m, 4.1942

13 Sheets-Shoot I6 DWHVTOR Graces: W. Pcm'nus v Feb. 18, 1947. G, w, bflnug, 3D 2,415,967

mm THREE! Filed Feb. 4, 1942 1s Sheets-Sheet 9 INVENIDR GEORGE WP'ONTIUS m A TTORNE'Y Feb. 18, .1947. s. -w. PONTIUS, 3D 2,415,967

mm TURRET Fil ed Feb. 4, 1942 1s Sheets-Sheet 10 G, w. CNTIUS, an 2,415,967

' mm Txim'r i Filed Fab. 4.1942

13 She'ets-Sheqt 11 A TTORNEY Feb. 18,1947. 6. w. PONTIUS, 3b 5 2,415,967

GUN TURRET Filed F sh. 4, 1942 13 Sheets-Sheet 12 'FTIQZZA a INVENTOR Gamma: W. Pow-nus m ATTORNEY Feb. 18, 1947. w, 'nus, 3 2,415,967

GUN TURRET Filed Feb. 4. 1942 '13 Sheets-Sheet 15 I! F F a w I I\ 2 n. m w e a I TT 3h] Q N N a nvvzm'on It GEORGE W. Powrrus BY m Patented Feb. 18, 1947 UNITED- STATES 1 PAT 2,415,967 oFFw v GUN runner George W. Pontius, III South Bend, 7 to Bendix Aviation Corporation, Ind., a corporation of Delaware Ind., alarm South Bend,

- Application February 4, 1942 Serial rim-429,439

. l Thisinvention relates to gun turrets and'more particularly to a gun turret for protecting the upper surfaces of land, sea or air vehicles. The turret shown in this application is applicable to tanks, trucks, torpedo boats, airplanes or land fortification. The turret will be described,

' however, but for purposes of illustration only and 6 Claims. (Cl. 89-375) usually mounted toward the rear of the fuselage where the surface slopes downward. In such installations the guns can point horizontally or 1 not as a' limitation of the invention, as designed I for use with an airplane. a

e The defense or military airplanes, particularly bombers, involves the defense of separate areas with relation to the airplane. One area of defenseis the area above the airplane and the present invention is described with reference to an upper turret to deiend this area. When a tail gunneris not used; the upper, turret must defend this vital spot also. For this purpose the vertical fins of the tail are separated to allow firing in the "straight bac zone. An upper turret must be able to cover a'complete hemisphere of fire to properly protect the upper portions of an airplane. I have accordingly designed an electrically driven turret which has two synchronizing guns that move in elevation through a 90 degree are, the turret itself rotating 360 degrees in azimuth. The gunner.

moves in azimuth withthe turret and sights the guns in elevation. To allow use ofthe turret as. an observation post as well-a transparent canopy,

streamlined as far as practicable, is placed over pendent upon 5. 1 solenoid motors controlled by a button switch."

below horizontal to the rear without striking the fuselage, whereas when pointing: forward the guns point above horizontal in their lowest position. I have therefore provided automatic lower limits for movement in elevation which are'deposition of theturret in azimuth. Also I'have provided an automatic upper limit at the straight up or zenith position. Another feature of the control system is the use of dynamic braking in stopping or reversing movement in elevation or azimuth.

The guns are fired by power units comprising Automatic cutouts for the firing system are provided to prevent the guns from shooting at parts of the airplane such as wings or tail members. Each gun is provided with hydraulic =chargers controlled by a solenoid valve and operated by a button switch. If ei her gun becomes jammed physical positionirom time to eyes to sight along the guns.

due to a dud, the gunner merelygpresses the switch charging both guns. 1 1

In most turrets the gunner must change his time to allow his This has proved "unsatisfactory becausea gunner cannot train his guns upon rapidly must at the same time the top of the turret and projects above the general surface of the airplane fuselage.

The movements of the turret in azimuth and elevation are controlled by the gunner. The turret is rotatably secured at its lower end inside the airplane, and the azimuth drive is applied to the turret at that lower end. This type or drive is advantageous over the usual ring gear drive at the top of theturret, ince an. airplane is essentially a flexing structure to accommodate the high '-stresses necessary in light weight construction.

- field of sight in the move through an arc of 90 degrees.

turret, and allows the gunner to sit or stand in Any driving member secured to or near the "skin" movement and is not as accurate 2. driving unit as'one secured to the interior of the airplane. The upper part of the turret is supported on a central rotatable column and is guided horizontally by roller contacting a circular rim at the fuselage surface. 1 e

I have also provided a novel type of control box for the electrical motors driving the turret oi the airplane is therefore subject to relative a fixed comfortable position and sight the guns at anypointin the hemisphere of fire.

The periscope is provided with intersecting cross hairs which move relative to the field of sight for ballistics compensation and lead. These cross-hairs are automatically moved by electrical devices in response to position of the guns in elevation and azimuth and in response to the relative speed of the target. The intersection point of the cross hairs marks the point in the field of in azimuth and in elevation. This control box allows sensitive control of speed in two or more distinct speed ranges for either the azimuth or elevation moton, Movement in azimuth is independent of movement in elevation and vice versa, and both movements are controlled by a.

single control handle gripped by the gunner.

The lower limit of movement of the guns in elevation is dependent upon the shape of the fuselage adjacent to the turret. The turret is sight which the bullets will hit at a chosen range,

air speed, air density and lead. In order to hit the target the. gunner merely moves the guns and consequently. the periscope so that the cross hairs intersect on the target.

Objects It is therefore an object of this invention to provide an upper or top turret having at least a full hemisphere of fire.

It is an object to provide a turret having a transparentcanopy permitting use as an observation It is an object to provide a turret mounted on a central column and driven in azimuth through this central column.

It is an object to provide an electrically driven and operated turret.

It 'is an object to provide a control box for the turret which gives sensitive speed control through a large range.

I It is .an object to provide a power operated turret having automatic limit stops for the movement of the guns in elevation.

ItLis also an object of the inventionto provide a turret having automatic stops for movement in elevation which vary in accordance with the azimuth position of the turret.

It is an object to provide a turret having dynamic braking for cessation of movement.

It is anobject to provide power firing for the guns of a turret. 7

It is an object to provide the firing control of a turret with automatic cutouts to prevent shooting at parts 01' the vehicle in which the turret may be-mounted. I

It-is a further object to providea turret having power operated charging mechanisms.

. It is a further object to provide electrical controlsior the charging mechanism. a

4 ing gear mechanism, the brush assembly, electrical takeofls, and the hydraulic gland;

Figure 10 is an elevational view in section of the periscope showing the path of light rays therethrough;

Figure 1-1 is a view of the prism, lens and mirror of the periscope showing the paths of the rays of light from a vertical direction;

It is an object to provide a turret with a periscope whereby the gunner may observe the field in the elevation are without moving his head.

It is an object to provide a periscope having a movable member synchronized with the elevation movement 01' the guns to enable a gunner to observe the field at which the guns are firing. V

It is an object to provide aperiscope-with auto matically movable sighting means.

Figure 12 is an isometric view of the galvanometers controlling the cross hairs of the sighting mechanism included in the periscope,- and showing the periscope mirror;

Figure 13 is a diagram of the trigger circuit and electrical controls for the charging circuit, and the hydraulic conduits and mechanisms of the charger system, all Superimpcsed in solid lines on parts of the turret shown in dotted outline;

Figure 14 is an elevational view or the rear of the control box for the turret;

. Figure 15 1s a plan view in section of the control box along the line Iii-I5 of Figure 14;

Figure 16 is a detailed side view of the control box showing the shape and construction of the rocker arms which vary the electrical impulses; Figure 1'? is a sectional view of the control box showing the breaker cams and taken along the line I'I--I1 01' Figure 14;

Figure 18 is a detail sectional view 01' the control box showing the elevation control cam taken along the line I8-- I0 of Figure 15;

Figure 19 is a simplified wiring diagram of the power circuit; showing parts of the turret in I dotted outline and having superimposed thereon It is also an object to provide a turret with an automatic correction-for ballistic deflection and lead of guns on a target.

Other objects and features of theinvention will be apparent claims.

In the drawings forming a part of this specification:

Figure 1 is a perspective view of an airplane having an upper turret made in accordance with the invention;

Figure 2 is a vertical section through the airplane and the canopy of the turret showing a gunner operating the turret with the guns pointedtoward the rear 01' the airplane;

Figure 3 is a schematic sketch in isometric projection of the mechanical parts and movements of the turret;

Figure 4 is an elevational view of the turret mountedin an airplane, with the airplane broken away, the canopy'in section, and one gun removed, to show the construction and arrangement of parts;

Figure 5 is a plan view of the turret with the canopy removed to show more clearly the construction; g

Figure 6 is a detail plan view with part of an overhanging flange broken away of the rollers positioning the turret horizontally with respect of the airplane in which it is mounted;

Figure 7 is a sectional view of the rollers along the line 1 1 of Figure 6;

in the following descrlption and i vation and the relation to therotatable gun shaft H to which the hangars are attached;

Figure 9 is a view in vertical section through the bottom of the column on which the turret is mounted showing the rotatable column and drivin full lines a modified power circuit;

Figure 20 is a complete wiring diagram of the power circuit, showing parts of the turret in dotted outline and having superimposed thereon in full lines the complete power circuit;

Figure 21' is a wiring diagram of the sight compensation circuit showing parts of the turret in dotted outline and having superimposed thereon in solid lines the electrical circuit for varying the cross hairs in the periscope for sighting the guns; and 4 Figures 22A and 22B are each portions of the complete electrical turret and while Figures 22A is on one sheet and Figure 223 is on another sheet, they should be considered together. The two sheets will be referred to together as Figure 22.

Mechanical parts and movements The mounting of the turret is illustrated in Figure 1. An airplane I00 has mounted on the rear part of the fuselage a turret I02. The turret is adapted to rotate 360 for a given number of rotations. The tail of the airplane I00 includes vertical fins I03 which are separated to permit the turret to fire toward the rear.

The mounting of the turret is shown in detail in Figure 2. Secured to longitudinal members I04 of the airplane I00, is a base member I06 which rotatably supports a column I08. Secured to the top of rotatable column I08 is a frame member I I0 to which the guns I I2 are mounted for rotation in elevation. Also secured to frame H0 is a periscope 300 and an ammunition can IIB. A transparent canopy H8 covers the he manipulates, to rotate-the turret in azimuth 1n either direction or elevate or depress the anism mounted on the column I08 rotates in azi-.

muth, and the guns 2 and the movable part of the periscope rotate in elevation.

The mechanical parts and movements of the turret are shown schematically in Figure 3. At the bottom of the figure a high speed electrical motor I28 drives a motor shaft I30 to which is secured a worm I32. Worm I32 drives a worm wheel I34 secured to a drive shaft I36 to which is secured at the other end a driving worm I38. Drive worm I38 en ages a worm wheel I40 secured 'to rotatable column I08, and drives column I08 in rotation in either direction depending upon the direction of rotation of azimuthmotor I28.

Also secured to worm wheel I84, is a compensator drive shaft I42 to which is secured a compensator worm I43. Worm I43 drives compensator worm wheel I46 to which is connected compensator shaft I48. Mounted on compensator shaft I48 is a. trigger cam 508 and azimuth limit stop cams 404, 406, 408, and M0. The word "compensator is applied to several ofthe parts just. identified because a .cam unit 604, which forms part of the sight compensator circuit; is also driven by compensator shaft I48.

The gear reduction between compensator worm wheel I46 and worm I43 is the same as that between column worm wheel I40 and driving worm I 38,resulting in compensator shaft 148 rotating one revolution for every revolution of column I08 and rotating in synchronism.

The other part of spur gear 804 engages a second double rack 306 the other end of which drives a gear 308. Gear 308 is secured to a prism shaft 8I0 on which is mounted for rotation the periscope prism 3I2. Through mechanism which will be later described, the rotation of prism 3I2 in synchronism with the elevation movement of the guns enables .the gunner toobserve at all times the field into which the guns are firing at any iven time.

A complete turret is shown in Figure 4 in which parts identified in Figures 2 and 3 are readily recognizable. Secured to stationary base I06 is the azimuth motor I28, and an azimuth compensator box I45 housing the compensator and cam mechanism. Also secured to base I06 is a solenoid operated charger valve 590 for regulating the flow of hydraulic fluid to the chargers for the guns. A brush box I05 encloses the electrical brush mechanism which will be later.

- described.

- band I 26 tightened bya handle I21.

The foot rest I24 is secured to column I08by a Seat I22 4 is mounted on a triangularly shaped bracket I23 the right of control box 400; is a relaybox 429 Rotatable column I08 is preferably made of preferably magnesium or aluminum and may be made by casting. An opening III in the frame IIO provides a place in which the gunner may his body for operating the turret. The guns II2 are secured to a rotatable gun shaft I44 supported near each gun by frame brackets H3.

Gun shaft I44 is driven in elevation by a high speedelectrical motor I46 positioned within a well I09 in frame IIO. Motor I46 drives a motor shaft I48 to which is secured worm I50 engaging driving worm wheel I52 mounted on a drive shaft I54. Secured on the other endof drive shaft I54 is a driving worm I56 engaging a worm wheel sector I58 secured to gun shaft I44. The gun shaft is rotated in either direction by reversing elevation motor I46, elevating or depressing the guns according to direction of rotation of motor I46.

' Figure 4, fairing ll4is supported by an The elevation compensator drive is obtained I through a bevel gear I62 secured'to shaft I44, and driving a matching bevel gear I64 which drives elevation compensator shaft I66. Fasthe elevation movement of the guns is about 90, the rotation of compensator shaft I66 is multiplied about three times to increase sensitivity of gear I is fastened to gun shaft I44 and en- 'gages the teeth of a double rack 302, the other end of which engages a double spur gear 304.

tened to compensator shaft I66 is an elevation trigger cam- 5I0, and limit cams M2, 4, M6 and 8, as well as a compensator cam 606. Since also secured to the column I08. Just below control unit 400 is a hydraulic conduit outlet 594 to which is attached a conduit leading up to the gun chargers as will be explained later.

The frame I I0, secured to the top of column I08 is guided axially by rollers I10 and I12. The rollers grip either side of a cylindrical rim I14 secured to longitudinal members I16 of the airplane I00. The construction and placement of the rollers will be more fully described later.

Secured to the top outer edge of frame H0 is a cylindrical fairing I I4 having a channel cross section with inturned edges. This fairing continues the sides of the canopy H8 and presents -a smooth surface on the. otherwise exposed-parts of the turret which would occur at the lateral edges of the turretwhere the rounded fuselage of the airplane I00 curves away from the high position shown in Figure 4. At the right in rm Il5securedtoframe H0. a a Ammunition can H6 is held to frame IIO by a rod II1 passing through an ear (not shown) on the frame IIO. Thelower end of ammunition can I16 is held to column I08 by a band H9.

Secured to the top of ammunition can H6 is a shaft I13 on which is mounted a roller (not shown) over which the belted ammunition is drawn during firing of the guns I I2.

The elevation gea'r' mechanism shown schematically in Figure 3 is also shown in Figure 4.

' An angle member I18 bolted to the top of frame H0 has fastened thereto a housing 180 comprising parts IBM and I-00b. Part Ia houses gear sector I58 (Figure 3) and driving worm I56 and part I80b houses worm wheel I52 and motor worm I50. Elevation motor I46 is secured to housing I80b. Gun mounting shaft I44 is rotatably held in housing I80a and has secured thereto a gun arm I 82 supporting a recoil absorbing unit I84 through which the gun barrel passes and receives its support. The details of gun arm 'I82 will be describ'd later.

Also shown in Figure 4 is the gun feeding mechanism; Gun arm I82 has secured thereto a roller I86. Belted ammunition is taken from ammunition can H6 and passed over its roller the gun shaft (not shown) mounted on shaft I13, and passed under and around the right side of roller I86 to the top of tapered roller I88. The belted am- 'munition then rolls around tapered roller I88 into the gun as more fully described in applica-- tion Serial No. 401,574, filed July 9, 1941, now Patent No. 2,379,185, issued June 26, 1945, on behalf of Royal J. Reek.

The parts of the periscope 300. are also shown in Figure 4. r The periscope as a whole is secured to the upper part ofhousing IBM. The prism operating mechanisms include the gear I60 secured to gun shaft I44 and the driven rack memher 302 including a turnbuckle 303 for adjusting the lengths of the member 302. The actual structure of the gear 304 and the rack members 302 and 306 is shown in Figure 4 where it is apparent that the member 302 is outside the member 306 with relation to the perlscope 300 where both contact spur gear 304. This showing differs from the schematic showing of Figure 3 v where the positions of the two rack members on gear 304 were interchanged for purposes of clarity.

The turret is shown in a top view in Figure 5. It will be noted that each gun II2 has a firing solenoid 512 for firing the guns and a hydraulic elevation, and the bolt 204 may be adjusted in slot 202 to alignthe gun in azimuth. Slot 202 is just slightly longer than the recoil stroke of the gun, and permits the gun to reciprocate freely in recoil. Thus it appears from Figure 8 that the guns II2 are not directly fastened to gun shaft I44 as shown in Figure 3 but are mounted in a gun arm instead.

The construction of the lower part of the turret is shown in Figure 9. The base member I06 is formed in five sections, a base member I06 a gear cover plate I06b, a cover ring I06c, a colunm cover I06d, and a hydraulic gland unit 580. A two-way thrust bearing 206 is secured to base I06a by a hollow bolt member 208 tightened against base I06a by a threaded fitting 2 I0. An oxygentube 2I'2 passes through fitting 2I0 and into an elbow 2I4 screwed into fitting 2I0.

The upper end of tube 2I2 is fastened to the frame H0 and has a convenient outlet for the gunner to supply oxygen at high altitudes. The tube2l2 rotates with column I08 in fitting 2I0 and elbow 2 I4.

Secured to the bottom of column I08 is a cylindrical member 2 I6 which rests on the rotata'ble part of bearing 206. Secured to sleeve 2I6 is the ring gear I40 (Figure 3) through which the charger cylinder 5I4 for charging the guns. The

details of the gun feed mechanisms show clearly in this view. A plate I81 is fastened to the top of each gun and has secured to it a spindle I 89 upon which tapered rollers I88 rotate. Secured on the ends of spindles I89 Near the large ends of rollers I88 are guiding hoods I92 and to the rearof tapered roller I88 is a rimmed roller I94 rotatably secured to plate I81 and used to align the cartridges with the ammunition opening in the guns II2, as is completely described in application Serial No. 401,- 574 mentioned above. The rollers I86 fastened to gun arms I82 are also shown in Figure 5, and the ammunition cans II6 are just below.

The placement of the guide rollers is shown in Figures 6 and '1. It will be noted that a set of rollers I10 and I12 is placedat each rear.

corner of the frame H0. The outer roller I10 is spaced between the two inner rollers I12-and the three are positioned to grip rim I14 without play. This structure permits free rotation of the' turret even though the rim I14 might be momentarily deformed by extreme stresses in the airplan I00. The rollers I10 and I12 absorb all are guide plates I90.

turret is driven in azimuth by worm I38. It will be noted that cover ring I06c retains an annular seal 2I8 to keep gear lubricant from leaking to other parts.

The structure of the electrical contacts at the base of column I08 are also shown in Figure 9.

Electrical conductors are necessary for passing current to the control box'400, and from the control box to the azimuth motor. Also telephone, charger and trigger and compensator connections must be made between the rotatable part of the turret and the stationary base I06. A

sleeve 220 of insulator material surrounds column sleeve 2I6. Alternately spaced on sleeve 220 are insulator rings 222' and slip rings 224 of conductormaterial. The brush box I05 retains brushes 228 which are, spring pressed against slip rings 224 and which are in several vertical rows to allow spacing of the brush units. -Wires 228 are con- I nected to each brush, and lead from' brush box recoil of the'guns as well as wind loads and other transverse loads to which the turret is the recoil unit I84 through which the barrel of gun I I2 passes as shown in Figure 4.

The rear part of gun II2 is supported by an L-shaped bracket 200 adjustably secured to arm- I82 and having a slot 202 longitudinally of the gun II2. Placed in slot 202 is a transverse bolt 204 secured to the gun II2 which bolt in turn supports the gun. The bracket 200 may be moved up and down for alignment of the gun in I05 to the various parts.

The takeofis inside column sleeve 2I6 are-also shown in Figure 9. A section of the sleeve 2I6 is replaced with an insulator piece 230. Passing through insulator 230 arewires 232 secured to I the slip rings 224. Wires 232 rotate with column I08 and pass up through it to the various parts to which they'are connected.

The hydraulic gland 580 is used to pass fluid to, and to receive fluid from the hydraulic chargers 5I4 (Figure 5) The gland has secured thereto an elbow fitting 582 to which is connected a conduit 584 leading to the solenoid valve 590 (Figure 4). Held in gland 580 against, sleeve 2 I6 are rubber sealing rings 588 to prevent leakage of fluid. Acolumn tube 586 passes through sleeve 2I6 and communicates with the fluid space of gland 580. The upper end of tube 586 is connected to the fitting 594 (Figure 4) passing through column I08.

The periscope and its operation and an eye piece 3I8. The sightbox 3I4 has rotatably mounted therein the prism 3I2 (Figure 3) held against a plate 3I9 by a clamp bar 320 and having corners A, B, and C.

rotates on shaft 316 through an angle'of about .45 from the position in Figure 10 shown in solid lines to that shown in broken lines.

"the lens.

The prism n the upper face of sightbox 3| 4 is a window 322 in which is placed a pane of plate glass 324. A horizontal partition 326 divides sightbox 3|4 into an upper prism compartment 328 and a lower meter compartment 336.

A flexible opaque sheet 332. secured to prism ing window 322 from striking the lower surface of prism 3l2.

Light entering through window 322 to prism "3l2 is refracted and reflected from prism M2 to i an objective lens unit33'4 heldin partition 326. After passing through: lens 334 the light is reflected from a periscope mirror 336 held in position by a standard 338 secured to' partition 326. The light thus reflected forms an image on the plane I-.-I just to the left of mirror 336. Rays of light from the image on plane II. pass through two convex lenses 343 and 342 which aid appear upright to the gunner using the eri- Jascope. Secured to the bottom of sight box 3 is a cover plate 345 to which is secured a cross Again referring toFigure 10, secured to sight box 3 is the central tube 3l6. This tube retains two sets of two lenses each of which lenses cooperates with the lenses 343 and 342 of sight box 314 in making the image appear upright. .One set of lenses 346 and 348 are mounted in a longitudinally movable housing 344 placed inthe l0 clamp 326 and partition 326 prevent light enter- It will be noted that the top ray T is at the bottom of the image'in plane II and that the bottom ray B is at the top. From this it is apparent that, the image is inverted, and to aid the gunner in training the guns on a target the inverted image iserected; Light from the image of plane II passes through lenses 343, 342, 346, 348, 354 and 356 which invert the image of plane -II, giving an upright image on plane 12-12.

That the image on plane 12-12 is upright is shown by the fact that the top ray T isvat the top of the image and the bottom ray B; is at the bottom. The rays. from image I2--I2 pass through eye piece lenses 360 and 362 to the point where the eye of the gunner would normally 'view the image. There is substantially no magnification of the image in the eye piece 3l3, so that r the field will be as large as possible.

The other extreme position of the lens 3l2 is shown in dotted outline in Figure 10. In this position the center rayC will be vertical corre- .sponding to a vertical or zenith position of the in the erector function of making the image guns. It will be noted that the rotation of prism 3i 2 from one extremeto the other is oniyhalf of the angular movementof the guns. This is due to the mirror function'of prism face AC' of the prism 3l2, resulting in the field rotating twice as much as the mirror rotates.

The path or the rays in the zenith position is shown in Figure 11. The left ray T and the right ray B correspond to the top and bottom rays m paths from those shown.

rightpart of tube 3l6. A screw 356 passing I {through a slot .352 in central tube 3I6 is threaded into housing 344 and is tightened to adjustably position the housing 344 in the tube 3l6 to obtain the proper focus. In the left end of tube 3l6 ,are secured twotadditional lenses 354 and 356 ,to complete thezerector function of the various.

lenses. 1 on plane 62 -12 which is at the right face of a" plate glass member 358 also held in the left part I'Df central tube '3l6.

The erected image is projected or focused The eye piece3l3 is screwed'to the left end of utubew3l6, and retainsrtwo lenses 360 and.3.62

orespectively for viewing the image on plane I2---I2. A hollowsponge rubber cushion 364 is fastened to the left end of eye piece 3l8 for the gunnerto rest his head againstwhile looking through the periscope. The paths of the light rays through the periscope are also shown in Figure 10. The prism takes in a field of about in which T isa top .ray, 0 a center ray, and B a bottom ray of the field. The centerray .C is parallel to the axis of the guns for any given position of the guns in elevation and by .this means the gunner may sight his guns while looking through the periscope. The rays enter face A B of the prism M2 and are refracted to the reflecting surface The cross hair mechanism is shown in detail in Figure 12. The two'galvanometer '6) and 620 are fastened to cover plate 345 as shown in A C of the prism. The rays then leave the prism through the face 0' B and enter the ob-. jective lens 334. The guard 332 prevents light entering window 332 fromstriking face C B of After passing through the objective lens 334 the rays are reflected at right angles by Journalled in mechanism not shown. Secured to the rotor shaft 624 of H hair galvanometer 620 aretwo transverse members 626 preferably made of fine aluminum tubing or magnesium to reduce weight. Between the left ends of members 626 is stretched a fine wire 628 which is the H hair or the cross hair intersecting the field of theperlscope horizontally. The opposite or right ends of members 626 project beyond shaft 624 and have mounted thereon weights 636 to counterbalance the longer left ends. The transverse members on shaft 622 which support a vertical cross hair 632 are similar in construction to the transverse members 626 of shaft 624 except that theupper cross arm is curved to reach around the lens-unit 334 .(Figure 10). a

Each rotor shaft 624 and 622 is centered by a hair spring 634 secured to each end of the shaft and to adjustable arms 636 mounted on each cross-member 6I4. Only one hair spring for each shaft is shown inFigure 12, but the conmirror 336 and form an image in the plane II. struction on the other endsbf the rotor shaft (not shown) is similar. The current for actuating the galvanometer passes through the hairsprings of each shaft and in passing" through the rotor, causes the rotors M and BIB to'react J against the field of the permanent magnets GM and 820.

The electrical system for supplying current to the galvanometers to supply automatic sight correction will be described later.

Inoperating theperiscope, the gunner is positioned as shown in Figure 2, sitting on seat I22 sighting through the periscope and controlling thelazimuth and elevation movements of the guns.

Inmovement in azimuth the gunner and periscope rotate with the turret. In movement of the guns'in elevation, the prism 3 I 2 of the periscope rotates one-half as much as the guns through the driving connection shown in Figures 3 and 4 of gear I00,'rack 302, gear 304,-rack 306, gear 308 and shaft 8I0. The center of the field of the perlscope is aways at the point at which the guns are pointing and the gunner moves the turret and guns by observing his target through the periscope. The cross hairs 028 and 032 automatically move relative to the field of the periscope to indicate to the gunner the amount of lead and ballisticscorrection necessary for the bullets to hitthe target. The gunner merely moves the guns and turret, and con- Y sequently the periscope, so that the cross hairs alwaysllntersect on the target. The electrical system for moving the cross hairs will be described later.

The trigger and charger circuits operation) I The triggercircuit and charging circuit for and their the guns of the turret are shown in Figure 13.

Parts ofthc turret already identified are shown in broken outline including the center post I08, the ring gear I40, the driving worm I38 and the azimuth motor I28. Also shown is the azimuth compensator drive including worm wheel I46 and the driven azimuth trigger cam 508. On the upper end of the turret the guns 2 are mounted on shaft I44 and driven in elevation by elevation motor I40. Also shown in dotted outline is theelevation compensator drive including shaft on which is mounted elevation trigger cam The electrical trigger circuit and electrical and hydraulic charging circuit is superimposed in solid lines on the dotted outlineoi the turret.

A battery BI supplies current to a wire I leading through the brush box, up to the column, and

to the control handle 402 wherelt connects to a switch SI. Switch SI is the main power switch -for passing all current to the turret and when the gunner grips control handle 402 he closes switch SI by the act of grasping the control handle.

Because of this type of grip control the power will automatically be cut ofl. if the gunner is shot thus preventing injury to the turret or the airplane in which it is mounted.

When switch SI i closed current flows to a wire 2 which is connected to both finger of a double relay- LI Energizing relay LI causes current to flow through wires 3 and 4 to firing solenoids Fla and FM in housings 5l2 secured to the guns, causing the guns II2 to fire.

Branching from wire 2 near. the center post is a wire 5 leading to a switch $2 the other end of which is connected to a wire 6 leading down the column I08 and out the brush box to a solenoid H of hydraulic valve 590. Switch S2 is manually operated by the gunner whenever either gun ll: jams. Ciosingswitch 82 passes current to valv 590 causing it to open to pass hydraulic fluid from inlet pipe 592 to gland conduit 584, through the hydraulicgland 580 to conduit 588.

5 Fitting 5841s connected to conduit 586 which passes fluid thereto at which point fiexible tubing 581 is connected "leading to the chargers 5I4.

After the charging is completed switch S2 is opened deenergizing .valve 590 and allowing it to return to normal at which-time the hydraulic .fluid in the charger will flow through the valve to exhaust conduit 596.

In certain positions of the turret, the guns II2 will be pointing at a part of the airplane and if firing were possible, iniury to the airplane would result. For this purpose a cut out mechanism for the trigger systemis provided, which will now be described.

Also branching from wire 2 is a wire 1 leading to two wires'8 and 8. Wire 8 leads to a switch S3 actuated by elevation cam H0. Cam H0 is notched in a portion corresponding to the eleva- 'tion position of the guns at which the bullets will strike the airplane. When the guns move in elea, trigger switch. The other branch wire 9' connected to wire I leads down the column and through the brush box to a switch S4 actuated by azimuth trigger cam 508. Cam 508 is notched in a portion or portions corresponding to the azimuth position 01 the turret at which the bullets'will strike the airplane. When cam 500' rotates so that the notched portion is. opposite the switch S4, no current will flow to the trigger switch at that point.

'Connected to switch S4 is a wire I0 leading through the brush box up the central column to 40 join a wire II leading from switch S3. Wires I0 and H are connected to a wire I2 leading to a trigger switch S5 in the control handle 402.

When the gunner desires tofire he closes trigger switch S5 yvith his finger, passing current to a wire 13 leading to relay Ll, If current passes through wire-I3 the relay will be energized closing the circuit to the firing solenoids Fla and FM causing the guns to fire.

In operating the charger. circuit, the gunner will be seated in the turret gripping control handle 402 as shown. in Figure 2. Gripping control handle. 402 closes power switch SI permitting current to flow from battery BI up wire-I to the switch SI and through wire 2. Branch wire 5. is now energized, and if the guns should now jam, or if for other reasons the gunner should desire to. charge the guns, he merely closes charger switch S2 with his left hand while gripping handle 402 in his right hand. Current then passes through wire 6 down column I08 to the solenoid valve 590. Valve 500 opens to permit hydraulic fluid under pressure to enter conduit 584, pass through gland 580, up column conduit 586 and gunner vationtothis position the notch opens switch S8 and no'current can pass at that point to supply a no eiilect.

ing ease of operation.

the control box 400.

The control box 400 for the power system is wgrasps control handle 402. and in doing so closes power switch SI; This permits fiowof current through wire 2 to wire .1 from there to the wires .8 and 9 forming part of a parallel circuit to firing switch S5. .Currentin wire ,8 may be interrupted by a switch SSactuated by cam 5l0 synchronized with the elevation movement of the guns 2. The. other branch of the parallel cireuit,-wire 9 leads down the column and current flow is interrupted by switch S4 actuated by cam 508 synchronized with the azimuth movements of. the

turret. When either cam 5! or 508 rotates to a pointcorresponding to the point at which bullets would hit the. airplane, the respective circuit is broken. tions both correspond to a position where the bullets will strike part of the airplane, no current When the azimuth and elevation posiwill flowthrough either branch or the parallel circuit and closing the trigger switch S5 will have 1 When the position of the turret and guns is other thanthe cutout position, current will flow through one or both branches of the parallel cirucuitlwires 6, H and 6 and I respectivelyto wire i2 passing current to firing switch S5. When the gunner desires torire he merely presses switch S with his finger, passing current through. wire 13 to .reIay-LI and actuating it.

. Current then flows from wire 2 to wires 3 and 4 to the firing solenoids Fla and F2a causing the guns to fire. Release, of switch S5 breaks the circuit torelay LI, the power circuit tothe firing solenoid is broken and the guns cease fire. A relaylcontrol of firing is used to reduce the size of the manual switch to a minimum and incre s- The power system 1 Thepower system is the electrical c ntrol circuit for starting, "reversing, and stopping the azimuth and elevationmotors and for varying their speed. a The azimuth andelevation motors are direct current motors having a constant field.

Since the. free stroke and the frequency of breakerarm 444 is a constant the duration of contact of breaker arm- 444 and contact 450 is varied by varying the position of contact 450 with respect to thestroke of arm 444. Inthis way the breaker arm 444 may touch contact 450 having an adjustable screw 458 touching arm 1 at an intermediate point in its cycle of movement and remains in contact until the cycle bf movement again lifts it free. As shown in Figure 14, the contact 450 is in the neutral" position wherein there. is continuous contact with the breaker arm 444, causing the actuated relays to remain continuously open so that no current flows to the motors. The positioning of contact arm 452 is accomplished by a lever 454 pivoted on a rod 456 and 452. Stretched between contact arm 452 and lever 454 is a spring 460 holding the twoparts constantly against each other. Lever 454 in turn positioned by an adjustment screw. .462 cc..-

They are reversed by reversing their fields. The

speed of the motors is controlled, not by varying the armature voltage, but by varying .the dura-- tion of constant voltage.shots to the armav tures of the motors. The "shot control consists of an interrupted direct current wherein the frequency of the interruptions is constant, and the duration of the interruptions is .varied. The

this speed control is I mechanism for obtaining shown in Figures 14, 15, 16, 17 and 18. Figure 14 cover plate 426 to which the mechanism of the entire box is affixed so that the whole unit may be removed from column I08 (Figure 4) in one unit. Secured to plate 426 is a frame 428 which supports the inner ends of the control mechanism. Secured toframe 428 is an electric motor fshows a rear. view of the control box showing a 430 having a fan 432 secured to one end and a pulley 434 secured to the other. Through a drive which will be later explained, the motor 430 causes a shaft 440 to'rotate at a constant speed. Mounted on shaft 440 are eccentric cams 442 which strike a breaker arm 444 pivoted to a rod 446 and urged in a clockwise direction b .a spring 448secured to frame 428. i 1 Current {is grounded through breaker arm 444 i from relays which then actto interrupt the currentaswill be later. explained. Breaker arm 444 breaks against a grounded contact 450 held in a curved arm 452. also pivoted to rod 446.

which is covered with metal screen 468. fan 432 blows air through the screened covered tacting a double frustro-conical cam 464 which is axially movable to act as a cam. The ax position of ram 464 is controlled by the gum, and in this way the unner controls the duration of the current shots to the azimuth motor. iBetween the lower end of lever 454 and frame 428 is acompression spring 466 urging adjustment screw 462 in contact with cam 464,

The control box 400 is seen in vertical section -in Figure 15, which is a sectional view of the box from below looking upwardly.

The cover plate 426 has an opening in front of fan 432, The

opening to cool the motor and electrical contacts. Thepulley 48 on the other end of motor 430, through a be. dri es a pulley 438 connected to the rotary cam shaft 440.

Lever 45.4 is shown in Figure 15 and adjusting 'screw 462*is shown contacting double frustroconical cam 464. Asimilarlever 410 for operat- .ing the breaker arm for the elevation motor is also shown in Figure 15 pivotally mounted on rod 456. Lever 410 is similar inconstruction to lever 454 and operates in the same manner. It

is positioned however by a rotary cam 412 mounted on a rotatable hollow shaft 414. This structure is shown in detail in Figure 18, where the elevation cam 412 appears in profile. Shaft 414 rotates in a bushing 416 integrally formed with cover plate 426. The outer end of shaft 414 is enlarged toform a housing 418. Control handle 402 is rotatably secured to housing 418 by a stem 480. When the gunner pushes or pulls on handle 402 transversely to the axis of shaft 414 he will cause the shaft to rotate, rotating cam 412 and changing the position of lever .410.

Secured to stem 480 of control handle 402 is a gear. segment 462 contacting a rack 484., The azimuth cam 464 is secured to rack 484 and the inner end of the rack is positioned in abushing 486 integrally formed in frame 428. Rack 484 rotates with shaft 414 and consequently causes cam 464 to rotate. Since cam 464 is circular,

however, there is no effect on the azimuth adjustment due to rotation'of the cam. When the gunner wishes to change the speed of the azimuth .motor he merely rotates handle 402 on stem 480 causing gear segment 48.0 to movethe rack 484 in or out, and thereby moving cam 464.

The outlines of the control'levers 410 and 454 are shown in Figure 16. It will be noted that lever 454 has two screws 458 for positioning two contact arms 452. In all, there are four breaker

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