UF 830 A2 U58 NO. 2044 DESCRIPTION AND INSTRUCTIONS FOR THE USE OF THE ABERDEEN CHRONOGRAPH REVISED: FEBRUARY 1,1921 ENGINEER REPRODUCTION PLANT, WASHINGTON BARRACKS, D C 4645 830 MS8 Cornell University Library UF830.A2 U58 olin Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924030764579 NO. 2044 DESCRIPTION AND INSTRUCTIONS FOR THE USE OF THE ABERDEEN CHRONOGRAPH REVISED: FEBRUARY 1, 1921 UL~P 83 O a.5'3 ORDNANCE DEPARTMENT DOCUMENT NO. 2044 OFFICE OF THE CHIEF OF ORDNANCE PART 1 BRIEF DESCRIPTICM eg THE ABBBDEEM CHROMOORAPH This chronograph was developed at the Aberdeen Proving Oround during 1918 and so constructed that the time taken for a projectile to pass over a measured path may be read upon a scale directly from the record strip. The measured path referred to is the distance between two sheet tin screens placed fifty feet apart in front of the gun. Wires are lad from these screens to the chronograph and the record is obtained by an electric spark which functions at the instrument »Aien the projec- tile passes through the screen. The chronograph measures the time Interval between these two sparks as follows: A drum (Plate I) of known circumference (500 m/m) is rotated by a governed electric motor at a constant speed (25 revolu- tions per second). On the interior surface of this drum is carried a record strip of prepared paper which is held in position by centrifu- gal force. The linear velocity of this strip is 500 m/m x 26 r. p. s., or 12500 n/m per second. When the projectile passes through the first screen a spark jumps from the top spark point (Plate I), through the record strip, to the drum, perforating the paper strip. The drum con- tinues to revolve and when the projectile reaches the second screen a spark perforates the paper from a lower sparking point. The motor is then stopped, the strip removed and the distance between these two spark punctures measured, which gives the lime the projectile took to pass from the first to the second screen. Tor example: Assume that the distance between the first and the second spark mark (measured in the direction of rotation) is 850 m/ra. The time interval between the sparks must have been 1/50 of a second (250 m/m divided by 1E500 m/m) since the strip was moving at the rate of 12500 m/m a second. From this it follows that thie projectile, having traveled 50 feet in 1/50 of a second, must have been moving with an average velocity of 2500 f.s. (50x50). In actual operation, however, none of these calculations need be made. It is only necessary to lay the index of the direct reading scale upon the first (or high) spark mark and at the point a- long the scale where the lower mark falls read the velocity. By this means it is possible to know the velocity of a projectile within a few seconds after the firing of the gun. The third or lower spark point may be used if it is desired to place three screens in the path of the projectile. Each screen consists of a thin sheet of paraffined paper on each side of which is clamped a sheet of tin. (plate VII) The screen is held in a. small clip (Plate VIl) which presses s wire against each of the tin sheets. These wires are connected to a. storage battery or power plant and to the primary of a spark coil. When the point of the projectile passes throuigh the first sheet of tin and touches the se- cond which is on the rear side of the paraffined paper separator the electric circuit is completed between the two, there is a flow through the coil (Fig. 2) and a high potential is induced in the secondary of the coil. One wire of the secondary leads to one of the spark points and the other is grounded to the drum. Prom the time that the point of the projectilo first touches the screen until the spark has per- forated the record strip the projectile, moving at the usual veloci- ties encountered in practice, would have gone less than one centimeter. As approximately the same time must elapse when the projec- tile touches the second screen, for all practical purposes, each spark can be considered to have jumped at the instant that the pro- jectile touched the corresponding screen. The screens may be changed quickly and one set of three chronographs can take from thirty to sixty velocities in an hour from small caliber guns> The chronograph weighs 59 pounds. It does not require any special foundation and can be set up near the gun. Two 64 volt Exide batteries are required for the 110 volt circuit. To the above add the necessary screens (previously made up), wire for leads, clips and accessories, making a total weight of approximately 400 pounds varying with the number and size of the screens required. PART II INSTRnCTIOWS TOR OFERATIMG THE ABERDEEN CHROMOORAPH EQUIPMENT FOR FIELD WORK . The equipment reqiilred to take velocities in the field con- sists of the following: 1 chronograph. Z Batteries, portable set (each set consisting of 32 Type 4-AC-7 Exide Batteries, Aviation Service, U.S. Govt.) for 110 volt circuit. 1 Accessory case (Plate x) oontaining;- 1 Apparatus, fall Z Balls, steel (for fall apparatus) 2 Books, record 1 Book, instruction (containing tables) 2 Brushes, armature (for motor) 2 Bulbs, electric, 25 watt, 110 volt 6 Contacts, wire (for fall apparatus) 1 Counter , speed 6 Pencils 4 Resistances, 2 (250 ohms) 2 (735 ohms) 1 Scale , direct reading 1 Scale, millimeter (for use when distances between screens vary from fif%y feet) 2 Screwdrivers 1 Spring (for governor) 200 strips, record 1 Tape, steel (100 ft.) 2 Wrenches. Screens (previously made up and tested) 3 Clips, to hold screens 2 Stakes, about six feet long (pointed one end) 300 ft. Wire, double twisted, rubber covered. The total wei^t of the above is about 400 pounds. More satisfactory results will be obtained by using three chron- ographs which, however, neoessitstes additional batteries and wire. Having arrived near the gun proceed as follows: SCREENS FOR FIELD WORK Drive one of the stakes in the ground about fifty feet in front of the gun (for 3,? jnch and below) and drive thn other stake fifty feet from the firet stake, in the path the projectile will take. It 1e important that the distance between the stakes be exactly fifty feet. Attach a screen slip to the top of each Stake. Insert screens in the clips. Lay the gun on each screen by sig^iting through the bore. Fasten one pair of wires to the binding posts on each clip and lead the wires to the chronograph. An alternate method (but one that is not recommended) is o drive one stake fifty feet from the muizle of the gun and attach thereto the second screen. The first screen being suspended over the muizle and held flush with a STnall piece of wire. The wire leads are carried from the first and second screens to the chronograph as de- scribed under the first method, OPERATING THi:' CHRONOCSRAPH While one nan is setting up the screens as described the other operator should proceed as follows: Place the chronograph on the ground about 60 feet to one side and rear of the gun. For larger guns the distance should be increased (with the caliber) from 100 to SOO feet. Open the eover of the chron- ograph. Insert 250 ohms resistance for the 110 circuit and place the 25 watt lamp in its receptacle'. Place the batteries beside tiie chronop-aph and connect them to the two binding posts on the left hand side facing the instrument. Connect the two wires from the first screen to the two upper binding posts on the right hand side. Connect the two wires from the second screen to the two mid- dle binding posts on the right hand side* Throw on the current to the screens. Start the motor. Test the circuits by pushing the spark points to the left (away from the drum) and short circuiting the two top binding posts. A spark should jump from the top auxiliary spark point to the stop attached to the motor frame (1^*27, Fig. 1). Test the other circuit in the same manner by short circuiting the two middle binding posts. A spark should then jump from the auxiliary middle spark point. Insert record strip, with waxed side of paper outward from the inner surface of the drum. Hove spark points to the right. Set the spark points at the lowest position and lock with the plunger (^4, Fig. 1). This insures the first and second points being at nearly e^ual distances from the edges of the record strip. Vlhen three screens are used the points should be set at the highest position. Calibrate the chronograph before recording a set of velocities by taking at least five falls. Instructions for operating the Fall appa- ratus will be found in Part III. Move spark points to the left, remove the record strip and find the mean of the falls taken. Insert new record strip and move spark points to the right. AFTER THE GUN IS FIEBD Move spark points to the left. stop motor by shutting off the current and pressing gently on each aide of the drim with the fingers. Remove the record strip. Start the motor, insert new record strip, test screens and set the spark points to the right. An experienced operator will remove the record strip without stopping the motor. The new strip is always inserted while the motor is running. TO OBTAIN THE VELOCITY Place the direct reading scale (Plate VIII) on the strip. If the top spark perforation is to the right, place the right edge of the soale on this mark and read the velocity at the point where the lower spark comes on the scale. If the top spark perforation is to the left, place the left edge of the scale on this mark and read the velocity, as before, at the point where the lower mark appears. The calibration error having been determined, previous to the firing, by taking at least five falls and finding the mean, refer to Chart B for the correction which is added to or substraoted from the velocity read on the scale. If the gun is fired at an elevation of more than one degree refer to Chart C for the correction which is to be added to the velocity already corrected for calibration error. The velocity thus read is instrumental, or the velocity at a point midway between the screens. A number of foot seconds is added to the instrumental velocity to obtain the velocity at the muzzle. This correction is more fully discussed in Part V and may be found on Chart A. PART in. INSmUCTTON FOR OPERATING THE ABERDEEN CHRONOfflAPH PHtMANEWT IMSTALIATIOK BUTLDIKG. TEST SWITCH. SCREENS. CLIPS. FALL APPARATUS AND VOLTAGE. BUILDING, EQUIPMEtrr AND PIESONNEL. Any building will suffice. Preferably it should not be more than three or four hundred feet from the guns so that the resistance of the leads to any one screen will not exceed one ohm. A solid table 10 rt. long x2^ ft. wide and 2jft. high should be provided and the three chronographs placed in a row on this table about five feet apart (Plate IV). With each chronograph there should be; Apparatus , fall Book, instruction (containing tables) Book, record Pad and pencils Rack, to hold record strips (Plate VIII ) Scale, direct reading Scale, millimeter Strips, record One accessory case, complete for each set of three chronographs. For slow firing one operator will be sufficient. When a large number of rounds are to be recorded tbere should be an operator for each chronograph and in addition a man to test the circuits at the test switch, as well as to control the switches to the screens and give the firing signals. TEST SWITCH For permanent installation, where a large number of rounds are to be recorded daily it will be found expedient to install a special test switch (Plate IX) which will avoid the neccEslty of short oirouit- ing the auxiliary spark points on the chronograph. Additional resis- tance, condensers and colls are required. These are fasteiied under the table as shown In (Pig. 4), which also gives the wiring plans. SCREENS . The tin plate screens may be made according to the drawings shown in Fig. 5. The materials required (Plate Xt) are as follows: Cutter, tin plate Machine, bending Paraffin paper, building (by the roll) Tin, sheet, S6 gauge (.006- .007 thick) The building paper may be sawed into narrow rolls the required width for the different size screens. Two pieces of tin are required for each screen. Each side edge of the largest sheet will be crimped in the bending machine, allowing Bufflolent opening to place under each crimped edge the paraffined paper folded over the side edge of the smallest sheet of tin. Heat the paraffin in a galvanised iron pan, 6 inches deep x 18 Inches square and draw the paper strips through this. A more elaborate apparatus may be provided as shown on Plate XI a. After the paraffin has cooled place the uncrimped piece of tin on the paper and fold the side edges of the paper over the tin. insert the folded edges under the crimped sides of the largest piece of tin (the paraffined paper serving as insulation between the two pieces of tin). Clamp the crimped edges of the tin with the bending machine or a wood mallet. The paper should extend about one half inch beyond each end of the tin to prevent the operator from receiving a shock when placing the screen in a clip. SCREEN CUPS. The Screen Clip ma-y be made according to the drawings shown in Fig. 6. Extra clips should be provided to replace others when shot away which, however, should not occur very often. SCREEN STANDARD. To insure a definite screen distance of fifty feet under all conditions it is recommended that posts be fixed rigidly in the ground, with adjustable frames (Plate V). This insures accuracy and permits the gun to be fired at different elevations. The wires may be led to the poles underground in lead cables. One of the advantages of this chronograph is that variable screen distances are not required. WIRING. Vfhen several chronographs are connected to the same set of screens care should be taken to see that the leads to the aource of power be connected syaetrically in parallel. If the top binding posts on the left hand side of one instrument should be connected to the positive side of the line and the top post of one of the other instru- ments should be connected to the negative side, no spark will Jump when the corresponding leads on the right side are connected to the same screens. Fig. 3 gives a diagram for wiring one set of chronographs (con- sisting of three instriments) for taking velocities from any one of three gun platforms. By continuing this same scheme of v/iring any num- ber of chronograph sets may be used for taking velocities from any one of several gun platforms. FAIL APPARATUS . The chronographs should be calibrated frequently, by taking five or ten falls. To perform this operation set up the Fall Appar- atus (Fig. 1) and level it by means of the level bubble. Connect the two upper binding posts of the fall to the two top posts on the right side of the chronograph; the two lower binding posts of the fall to the two middle posts on the right side of the chronograph, 'Place the steel ball on the upper arm of fall and release the heunmer. The ball will teke one-fifth of a second to fall, during which time the drum will have made five revolutions. If the motor is running at normal speed the second spark mark will be exactly under the first. Should there bo any displacement from this correct position see chart B for the correction to be used. If, however, the distance between screens is other than fifty feet the formula for determining the velocity, given in Part V, should be used. If the upper spark mark is to the right of the lower spark mark the difference in millimeters should be added, and substracted if it is to the left. VOLTAGE. Insert the 260 ohm resistance unit on the front of the chron- ograph frig. 1) if the line voltage is 110 volts. If the voltage is 220 volts use the 735 ohm resistance unit. While the chronographs will operate on a 110 volt circuit, a 220 volt circuit is preferable for a permanent installation as a hotter and more distinct spark will be obtained. PART lY. DETAILED DESCRIPTIOM AND THEORETICAL DISCUSSIOM OF THE ABERDEEN CHRONOGRAPH. Chronographs designed for the measurement. of the short time in- tervals corresponding to the flight of a projectile over a limitael por- tion, of its trajectory depend, in their operation, upon two or more eleotrleal impulses caused by the projectile. With the Boulenge chron- ograph, which has proven practical for the measurement of projectile velocities, these impulses have consisted of breaks produced in the electrical circuits by the projectile, usually by a rupture of wire screens placed in its path. The breaking of any circuit by a. projec- tile is necessarily attended with certain irregularities. The broken ends of the wire may continue to make contact with the projectile on either side of the break for a variable length of time; the wires, especially if they are of copper, and insulated with cotton, may stretch appreciably before breaking; and the point at which the break takes place will also depend upon the relative position of the projec- tile and wires at the time of impact. As a result the measured inter- val is subject to a possible error from these sources alone as the distance between the points at which the breaks actually occur may differ from the measured distance between the screens in their normal positions. One in^jortant point of difference between the Aberdeen Chrono- graph and other short interval chronographs is that its record of an interval depends upon the closing rather than upon the opening of circuits. Thus the irregularities mentioned in connection with break KEY TO PLATE Xa CONTENTS OF ACCESSORY CASE 1 Base for Pall apparatus 2 Rod and Top Contact for Fall apparatus 3 Steel Balls for Pall apparatus (2) 4 Record Books for recording valocities 6 Instruction Book 6 Carbon Brushes for motor 7 Lamps, 25 watt, Edison base (2) 8 Contact Wires for Fall apparatus 9 Speed Counter 10 Lead Feneils (6) 11 Resistance Units (2) 260 ohtis; (2) 735 ohms 12 Direct Reading Scale IS Millimeter Scale 14 Screwdrivers (2) 15 Spring for Governor 16 Record Strips (500) 17 Steel Tape, 100 feet 18 Wrenches (2) 19 Grease, li^t PLATE XA circuits are eliminated, as a result, shorter screen distances may be used without sacrificing accuracy in the measured interval; also several chronographs may be connected to the same set of screens. The chronograph itself will now be considered in detail. DRtM. A shallow cylindrical drum, (1) (Fig. I) of SOO m/m inner cir- cumference, mounted with its axis vertical, is driven at a constant speed by a small electrical motor. The drum, being of oast aluminum requires little power to bring it to the normal speed 8f 25 revolu- tions per second, (which it acquires in about fifteen seconds). On its inner periphery, a strip of prepared paper (the record strip), equal in length to the circumference of the drum (500 ra/m) is held in place by centrifugal force. Since the linear velocity of this strip is there- fore determined ( 12S00 m/m per second) the time corresponding to any two spark marks on the ribbon can at once be determined from the fun- damental relationship. t equa Is D where t is the time in seconds and D the distance between spark marks, measured in millimeters in the direction of rotation. With the time thus determined the velocity of the projectile can be found from the equation, V equals ^ where V is the velocity of the projectile in "feet per second" and s the distance in feet between screens. These two equations may, of course, be combined and written (eliminating t) V equals ^^^°° S D MOTOR . The motor (2) (Fig.l) is series wound, 110 volt direct current. provided with ball bsarings. When operating on a 110 volt circuit ft resistance unit (3) of 260 ohms is connected in series with the motor. When used on a 220 volt oircuit this resistance is changed to one of 735 ohms. GOVHtMOR. On the lower end of the motor shaft is the governor (4) (Fig. I) rotating with the motor armatvore. Its function is to maintain the speed of the motor constant by regulating the supply of current to the motor. At K speed less than 25 r.p.s.i the contact at (5) keeps the lamp re- sistance (9) short-circuited, and the full line voltage is impressed on the motor. When the speed exceeds the value at which it is to be maintained, the governing mass (6^ moves outward, due to its centri- fugal force exceeding the tension of the spring (7). Since the gov- erning mass ia rigidly connected to the bent lever which carries the tungstan point (5) and this lever is pivoted at (8), the outward motion of the weight (6] breaks the contact. The diminished current thus supplied the motor by introducing the resistance (9), 25 Wt. lamp. In series with the motor, reduces the speed. When, however, the speed again reaches its normal value the contact (5) is closed, and the cycle repeated. This happens many times a second. RECORDING SYSTEM The recording system of the chronograph, which is entirely electrical, consists of three independent units, one for each screen and corresponding spark point. Each unit is composed of the following elements: COHDENSmS To produce a spark when a make circuit is used, a condenser (12) (Figs. 1 4 2) is employed. This is a paraffined paper condenser of 10 microfarads capacity (made up of fiTo units of 2 microfarads cap- acity each) and charged from the line which supplies the motor. The charge passes into the condenser from the line thru the charging re- sistance (14) and (15). CHftROTHG RESISTANCES These resistance units (14) and (IS) (Figs. 1 & 2) of 5000 ohms each, are connected between the respective condenser terminals and the line. Their pin-pose is to protect the line against excessiTe currents when the condenser is closed on a circuit of low resistance. IHDtrCTION COIL The discharge of the condenser thru the primary (16) (Figs. 1 ic 2) of the induction coil induces a sufficiently high voltage in the secondary (IV) to cause a jump spark between the point (11) (connected to one side of the secondary) and the drum. The circuit from the other side of the secondary is connected to the frame of the motor, (18) thence thru the motor to the drum. The primary of the induction coil is composed of 170 turns of #16 enameled wire, the secondary of 15000 turns of #32 enameled wire. The core of the coil consists of 8 oz. of fjJO soft iron wire. PRiroiPLE OF OPmATIOW OF AHXILIARY CONDEHSERS The main condenser (12) stores up a quantity of electricity (determined by the line voltage and the capacity of this condenser) which is suddenly released through the prijnary (16) of the spark coil when the screen circuit is closed by the projectile. The charging re- sistances (14) and (15) prevent destructive currents in the line when the circuit is closed, but do not interfere with the complete charging of the condenser (12), the charging operation being merely retarded slightly by their presence. The screen oirciiit having a low resistance permits a considerable quantity of electricity to pass (15) even when the time during which the circuit is closed is of very short duration. This induces a sufficiently high potential difference in the secondary (17) to cause a spark to jump from point (11) to the drum. The very short tijne of contact limits this discharge, however, and does not per- mit all the available energy in the condenser to become transformed into energy in the form of a sparlc. To improve this condition and thereby secure a hotter spark, an auxiliary condenser (13) is connected across the leads to the screen. The capacity of this auxiliary condenser is approx- imately one-half that of (12). With this arrangement it will be noted that before contact occurs in the screen circuit, the potential differ- ence across (13) is the same as across (IZ) and that these potential differences oppose each other. When contact is made through the screen, (13) discharges more rapidly than (12); first, on account of its smaller oapaoity and second, because (12) must discharge through (16) which acts as a ohoke coil. Consequently after a very short interval (of the order of a millionth of a second) the potential difference of (13) has fallen considerably below that of (12), this condition sets up an oscillation in the circuit (12) (16) and (13) which persists after the screen con- tact hag ceased, and until both condensers have beer restored to the same potential difference by the voltage impressed from the line. A greater amount of energy is thus transformed in the coil, which results in a hotter spark and an easily discernible spot on the record strip. As previously stated any chrono^aph that relies upon the break- ing; o*" 9 circuit must be irregular to the extent that the break is irreg- ular. When a. wire carrying an electric current is broken an arc is form- ad and the duration of this arc is one variable factor. When such a wire is broken by a rapidly moving projectile, the projectile will keep in electrical contetot with each end of the broken wire for a short interval of time. As the projectile itself is a conductor, the circuit is thus not brokon until one of the wires ceases to touch it. This is another variable factor. When a long pointed projectile is used the point may pass between two wires, thus delaying the time of break for an interval depending on how close the wires are strung to- gether and also upon how tightly they are stretched. This is a third variable factor. Each time the screens are made up there is a slight change in the resistance of the circuit; a fourth variable. Moisture will also change the resistance making a fift.h variable factor. These variables are eliminated when flat metal screens are used to make a circuit. Evidence that the use of a make circuit eliminates the irregularities mentioned above, lies in the fact that the screen diatancee may be much reduced from standard (50 feet) without appre- ciably decreasing the accuracy of the registered velocities. Proof that the spark is obtained in the Aberdeen chronograph from the extreme point of the projectile appears to be confirmed by the fact that the chronograph functions perfectly when measuring the veloci- ty of the service rifle bullet. As the bullet is less than one inch long and is traveling at 2600 foot seconds, the time of contact is ne- 32 cessarily less than " of a second yet this is sufficient to give a spark; therefore the spark may be considered to jump at the in- stant the point of the projectile touches the second sheet of the screen. The variable in the speed of the motor can be kept constant to within one part in 500, The distance between spark marks can be read to within 1/5 of a millimeter; -with a distance of 500 m/m, (the length of the record Btrip) this would be one part in 2500. The obtained velocity should never differ from the true velocity by more than 3,4 parts in a thousand, the probable error in any one reading being only a small fraction of this amount, and this may bo reduced by using three instruments and taking the mean of their velo- cities. PART V TNSIRPCTIONS FOR CALCULATING THE raSTRDMENTAL AND MOZZLE 7EL0CITIES RECORDED WITH TBE ABERDEEK CHRONOaiAPH ISS-mUMENTAL VELOCITy Should a direot reading soale (Plate VIII) be broken or not obtainable, or the distance between screens be other than fifty feet, measure the distance between the spark perforations with a milliineter scale (Plate VIII ) and compute the velocity by the following method: V equals ^ ° ^ D equals distance between sparks in millimeters C equals inside eirounference of drum, (500 m/is) S equals distance between screens in feet R equals number of revolutions of the drum per second, (25) As the sum of RC is constant we have; V equals i2600_S but as the Fall apparatus (Part III) will probably show an error due to the inconstancy of the motor speed (known as the calibration error) it will be necessary to add or substraet this error from the sum of RC, hence: „ , _ (12500 plus or minus 5 times) V «<1"^1« S ( h,e calibration error) D MUZZLE VELOCITY The velocity thus read, or computed, is instrumental (or the velocity at a point midway between the screens). If a projectile loses velocity after leaving the muzzle of Ihe gun a number of foot seconds must be added to -Ihe instrumental veloeity to obtain the true velocity at the muzrle. This correetion is obtained from ■ttie follo»fing formula; ^ equal6(ii_2)i d equals square of -the bore of the gun, in inches (Table 2) X equa.le distance from muzile to point midway between screens w equals weight of projectile i equals a factor determined by the shape of the projectile (Table 1) Having obtained the Jj consult Chart A for the correction which is to be added to the instrumental velocity. STRIKING VELOCITY This formula is also used in determining the striking velocity *hen firing at armor plate. In this instance; X equals distance from muzzle to armor plate be Find the correction on Chart A which is to substraeted from Ihe muzzle velocity. CORRECTION FOR EIEVATION OF GUN Vlhen firing at any angle of elevation the actual path that the projectile takes is greater than the horizontal distance between screens. It follows, therefor, that the time needed would be greater and the velocity less. The correction is obtained by multiplying the horizontal distance between screens by the secant of the angle of ele- vation (Table 3). The result will be the actual distance between screens along the projectile path and should be used as (s) in the formula to determine the instrumental velocity. CORRECTIOII FOR THE VALUE OF i Vne value of i depends on -the shape of the projectile and is assumed to be independent of the caliber and the velocity. Since the correction to the muzzle is usually small, it is not important to know i aeeurately. For this reason all projectiles have been divided into seven classes and a certain value of i assigned to each class. the different classes are as follows: DESCEIPTICW NAME EXAMPLE VALUE OF i 7 caliber head Long point 6" Mark IV, shell .6 4 caliber head Medium point 4.7" Mark I. shell .6 2 caliber head Blunt point 155 m/m shrapnel 1.0 A. P. shell 12" A. P. shell without ballistic cap 1.2 Beveled cylinder Modified slug 4.7" slug 1.6 Slightly beveled Medium slug 9.2" slug 1.8 Square end Slug 16" slug 2.0 The fringing of poorly designed rotating bands may increase the values of 1 given by 30^ or more, boat tailing or the use of a different fuze may increase or decrease 1 by 10 ^ or more, and the large toler- ances in the shape of the bevel «j modified slugs may also easily Intro- duce variations in 1 between similar projectiles. Ihe value of i for several different projectiles is given in Table 1. I a; < h a; > h o o -1 lU 111 M K« e; > I- lU > -1 cc 1- z 111 t. ■D \- tO Z 0. o r o lU o 1 C J - O al 20 J . 5pJ 1-1- ] o g o 3 J] • ^ ;n i o <£ o xMS * ziS Ess S »J IE 1 1- S OOP* I- o m HI 5i J ;tix — — — n — — — ' -^ 1 8 6 10 6 o w v9 OJ ^ 8 ^ - S S S p o lU w o u p- d. > 1- z o (L iS z o 111 N > f ^- z D J 10 s 1 Q r a: J V - 3 J "« - ° ill t^ : a o o cj - r S s s s -- - o % S \ \ o \ ^ s \ Ps m N s s N ■) C ~^ N \ . \ ^ \ k \ V_ g ^ \ \ ^ \i^ ^ \ k \ i X N X s N ^r kH\ -L- 9 -^9 o* ~^ t^ ^^ ^ 1 K N. S \ - Sfi \ \l ^ \ -t S ?s -^ -^ \ X \ 1 N \ \ P ' ■^a ~^ ~x V N s s,^ v\ BS ~" •-~. \ \ \ \ \ \ \ \ 1 s 3? -^ ^ \ \ s \ \ \ \ o„ s§ ^ ^ --^ ^ =^ ^ \ s. \ \ \\i \ o --, \ •^ - -N \\\:\ --- ^ --- ^ -\ x\ X^ h^ \ \v\ < = --. >^ -~ \ "^ X s^ si\ in 8 ^ ^\ -^^ N s \ \'i V 9 r— " "-^ ->^" V \ \ ^ \\ 1 o — -^ ^ ^ ^ ^ \ \ \, \^\ ii '-J -. __ — ^ ^ r ^ \. \ \ ^\ 1 \ n g =t; - -= =; t; ;^ ^ "~^ ^ -^ ^ X N. N, \ \ A - M 5 - K< \\ " — '~'~~ :> T^^ A™ \ N ■ ■— —J ^N i \! r^" ? _ — , „l -4^ \ .N » "~ ~ . , 1 — . > o — — — -- ■ ^- — ~ t= = _^_^ I: —- >. g 1 1 ^ j^^- — — — — =* ^^^ = — — ^ ^^^ — — — lO 1 1 ^^^ ^^s. o P: OP ^i xn a z S- 3 Zi-J 01 E h OOK DO0Z 009Z OOkZ 003Z OOOZ OOVl 0O9I OOVI OOZI 0001 009 009 OOfr ooz , . . a 1 ^ ?» 1^^ i^S t *^ 4:1^^ !S^ 1^- Iv 5l ?!if>l. ^5 ti- 13 s^ ^-s^^^^ <^ ^ X >i ?:fe?53^ ^^ ^- ^^ ^^< ^Iv'^* \% Cj S f;52 i;^§M- viS"^ \ |i?« ^SLS'i 5^ A \\'^ ^^X^l ^^ \ s^ ^^Ptcl 5 X .^^5 5^^^S ^ ^ol ^53^b 5 S^i *^S^5 \ 5&*= |>»cK§ r N >lb i^^safc ~ ^ ^ 1?^ .!55^a ^\ \ fcis ^$9^*^ 3 \. ^ ^ 3 X ^ V334 o< ''v ^ \ " ^ V ^ ^ 5 \-^ -oS ^ N ^^ " \ A ^ ^ r-tt^ S ■^^ ^ ^ N X 3 3 CXU ^ ^^ \ S" ^ ^^ X L. 333 1 ^ ^^ ^^ ^ V \ X A 5^^L3 1 ^ \ V 5 ^^ xVXxi ^ "^^ "^^ - "^^ ^ X A txxx ^.. ^v - ^ V V vV 3X ^^ ^v- \ ^^ X X v-tVX ->• ^■^ ^^ ^s ^ S V vXXXU ^" ^ ^^ ^v V \ ^ V 3X^ 5 ■^^ N. ^^^ ^^ ^ ^^V^XC iv - ^^ s s, N XxxvX ^-- ^^- ^^ ^ V ^^^^xs ^-^ ^ ^^ \ N^^^^^V^H "■^ ^^ ^ ^v \ s ^3xxa ^^^ ^^ ^^ V V s^^^V^W ^^- ^^ ^N ^^ ^^^^UOT ^ \ '^^S \:3xQ ^ "^-^ >-- ^^ \ s ^XXQS s v^ ■^■^^ - ^^ ^ ^ ^^^^xar ^• "* -~~,__ ^-^ ^^ ^^ ^ \SxQiL 5 "~ ~^ ^ ^^ % ^ v^^vK i^? ^ — ^ ^- =='^^ :^N;ASffi i»S *)-_ ~"'~--- =-- ^ ^^^S\5l= ^^ ---^^ ■^-^ ■-^^v.^Sil: Z^- '^ = = r=.= >_^. • It l+m+fm^ffl MM |^ |s l« i^ KEY TO FIOTIRE 1 DIAGRAM OF THE ABERDEEN CHRONOORAFH , HARK IV 1 Drvm 2 Motor 3 Resistanoa Unit (250 ohma for 110 ▼. , and 735 ohms for 220 v.) 4 QoTomor 6 Contact Point (Ooyarnor) 6 Valght or QoTernlng mass (Governor) 7 spring (Governor) 8 Lever Pivot (Governor) 9 Lamp Resistanoa between motor and. governor. 25 w. , Edison base. 10 Adjustable Shaft, holding contact point 11 Spark Points 12 Condensers of 10 microfarad capacity 13 Auxiliary condensers of 6 microfarad capacity 14-15 Charging Resistances of 5000 ohms each 16 Primary of the Induction coll 17 secondary of the Induotion Coll IB Secondary connection on motor frame; also thru (26) and (LiUiN) to spark points , and as governor control thru (9) and (10) and (4) to motor 19 Fall apparatus 20-21 First and second screens 22 Switch to motor 23 Switch to screens and spark points 24 Plunger adjustment for spark points 25 Connection between A and 3 26 Connection between 9, 18 and 17 27 Stop, against which auxiliary spark 'points are tested BIMDIWG POSTS A-B From the batteries C-D Leads to the first screen E-F Leads to the second screen G-H Loads to the third screen L-M-N To the spark points Diagram of AJierc/een ChrortoGraliJi, Mk jUl ric. I. to fen zs Z6 zz n ■\e. M. ?Z4 -0/3 7^^^ f 7' 65 le. /J o — o- -5 — o o — o- 6 — O- Q /x /6 f-^- i fy 17 \ /J IS o [r^=^ -^^^ /^ ^ cO 0^ /J />? /7|k''*|Q/^ ni' /7: \IS Kj- /■/ i/-^ /^77 of Con7iectlo7i6 for fleasurmg Fyojectile Vefocitj with Tm Screens; (7/^0 S^oy\fm^ fc^JI /i/j/jard/as. 3 v^ /« (> /:x g Instrument Section /iherdeen Fhovina Ground,f1t/. KEY TO FIGURE 3 DIACatAM FOR WIRIWG OWE SET OP THREE CHRO- NOGRAFHS FOR THREE GUH FLATFQBM8 A Gun plfttforns B First sereene C Second screena D Chronoeraphs E Test Switch F Panel switch for third gun platform G Panel switch for second gun platform H Panel switch for first g^ platform J Power line s ^ s 11 a /^/G. 3 m= ( V ( -o r^ hulrvmenl iSeclion. AherdeeTi Fi'oying Ground ^. ^ KEY TO nOUHE 4 TEST SWITCH A Test (spark) points on switch B Test eide of switch C Screen thru Test Switch to chronograph D Coil, Type 36, (Pfatietiehl, Chloago, 111.) E Condensers, 6 mierofarad eapaelty T Resistances, 5000 ohms each First screen to chronograph H Second screen to chronograph J Power line to chronograph K First screen to Test Switch L Second screen to Test Switch M Panel switch to screens G-H multiple connected to screen contacts on the chronograph K-L multiple connected to wall panel switch (M) The coil hexes, condensers and resistances are most conveniently attached to the under side of the table top and the test switch mounted on the right end of the table. C5 Co Ik ^ ^ St W f ■ I 1 1,1, I I I I ''ill 'u |o lU I ■ CD si §i §i % IJ iii. Hi; ^ — *^^'»V^*A^V^ >i l9i t i>r ^K hi5uldtivi //w/f/e liii Imuldtiv^ fiajier Outoide tiv View of tin ond jiajjer he fore being folded. r/o.£. 6creen 3^zeJ. m inches. Cd Ctl. fsZ Jilt. 4-7" ml iz- ML hi 6cr. ZrtJ^rr. _6_ JZ^ 6' Udt /z ML. /^ J^ -yfi_ le A^ J2i. J2^ /s -j^ 18 Z6, et 7(. ^ htJcr. Znd.-icr -L4- -jbL. J±. J±. -M. -IB^ .^d- .^32_ -SS-. -sa_ -/t- .^i^.^ .^±. ^Z4_ J^ ^a ■3S x^ Jit 6cr. ZndScr /J _^iik. JlJL -Uk. Jllk. jLI. -Hl. -^^ -^_ :z z ZT. z z -TO- _.ll. .21 -JJ^ -lA, -/i_ J^ _i4S_ zz •So ^o Jo /at Jcr ZjtdSc,-. -LSL. J^ JIL JIL. _i^2_ -UL. -L5^ -Zo- .XiL. Jti- _^LS_ •f Z ■az /•s JA. J/L JiL .Ti. Zo .Ao_ SiL. -Zh- _v2fi_ _4Z. ^g ^AZ_ tjtJcr _ZndJer. JL. // J.S- J^ J^ .M- .Jl^ Zo -Z^ Zo UL. .JL. .J±. .M. .J2- JJ^ Zc _^a. _ze_ -^£l. -Zl /jtSer. f„dJen Jd- _2_ -IdL JS_ JS JS.. ja.. SI.. Z6 ZS_ Z6 J±. -2. -2. _2_ .J£. -t£. J^ -^- Z^ -ZlL. Jiy JS Note: l^fiere •seyeraf roaric/a of ^o call her are h hertfcorded the standard screen for the 4.7 Gon Jhould he used and ten or/nore shots fired thru each Jef of Jcreerfs. Tin Plate Screen For flhertJeen C/?ronogrM. JS fPitrument Section, ilier^&n Ffe vint Ground, /Id. id Screen Clip For /iherdeen Chrcno^nifih M. © " ■' u " £n a 11 B- FraTne C'Ocrecn D D Plan view oF cfifj for /io/(/(7if bottom of Jcreen Shomng Clih attached id jjost for fiefd oje. P D 'D C D a 6hoyvtng CJ(f> /itt ached To FraTne Fgr Fcrrnanent hs tall/it ion r/o.e. Z^ a "O" o & atb D. fist fjislrvmeTtt Section /^berdeevPronng Ground. (^ TABLE 1 VALUES CF THE COEFFICIEKT OF FORM 1 FOR DDTEREBT PROJECTHES PROJECTILE FUZE 1 S7 m/m H. E. Shell, Mk. II S7 m/m L. E. Shell, Mk, I Minor Caliber Base Detonating 1.00 .80 76 m/n H. E. Shell, Mk. I 76 m/n. H. B. Shell, Mk. I 76 Vm Shrapnel Long, Mk. in Short, Mk. V 1.10 1.16 1.10 4.7" H, E. Shell, Mk. I 4.7" H. E. Shell, Mk. I Short,Mk. V Long, Mk. Ill .90 .76 6" H. E. Shell, Mk. 11 Short, Mk. V .70 6" H. E. Shell 6" (Lipped Band) Short, Mk. V Short, Mk. V .70 1.00 166 m/m Hewitier Shrapnel 166 m/m H. E. Shell 46 See. Com. Short .66 .70 8" Gun, H. E. Shell 8" Howitzer, H. E. Shell, Mk. I 8" Howitier, H. E. Shell, Mk. I Long or Short Short, Mk. V Long, Mk. Ill .76 .90 .96 240 m/m Howitzer, Mk. I 240 m/m Howitier, Mk. VIII Mk. IV 1.10 .60 9.2" Howitzer .86 10" Long Point, Mk. II .66 12" Batignolle, 900 lb. • .60 14'.' Navy, Long Point, 1660 Ih. .50 14" Gun .60 Slug, Square End Slug, 4.7" Modified Slug, 166 n/» Modified All Calibers 2.00 1.66 1.60 SfC^NT T/^BLE TflBLZ n ESevation decant [Jevation 6ecant CJevatiov ^cavt EJevatiov •Secant /■ 'o I.OOOI z' -0 1.0006 J- O 1. 0014 4' /O0Z4 1 /.OOOl 1 1.0006 1 1.0014 1 lOOZS Z /OOOl z /.OOOC Z 1.00/4 z /.oozs J I.QOOZ •3 1.0006 3 /.00/4 J /.0OZ5 4 l.oooz 4 /.oooe, 4 /.00I4 4 /.00Z5 6 l.oooz •s /.0007 ■5 /.00/4 S /.OOZS 6 l.oooz 6 1.000 7 6 1.0016 6 /.OOZC 7 /.oooz 7 /.0007 7 /.00/5 7 /.ooze 8 AOOOZ a /.00O7 a /.00/6 B /.O0Zi> 9 /.oooz 9 1.0007 9 /.00/5 9 /.00Z6 /O IJIOOZ 10 /.O007 /o /OOIS /O /.OOZ6 II /.eooz // /.COO 7 //. /.60IS /I /.00Z7 /Z /.oooz /Z /.0007 /z /.oo/i. IZ /.OOZI 13 /.oooz /3 /.0OO7 /3 100 IC 13 /.00Z7 M /.oooz /< /MOOB /4 /.OOI6 14 /.oez7 IS /.oooz AT /.oooe IS /oo/e, IS /.OOZT It. /oooz /(. //>ooe /e, /.oo/t li, /.oeze 17 /oooz 17 /.oooe n /.OO/L n /.ooze IB /oooz /e /.oooe 16 /■Od/7 IB /.ooZB IS /.oooz 19 /oooe 13 1/1017 13 AooZS £0 /.ooo;s zo /.oooe Zc Ioo/j za 1.00 Z9 Zl /.eoo3 Zl /.eco6 Zl /.00/7 Zl I.OOZ9 zz /.OO03 zz /.eoo8 zz /oon ZZ /.ooze zs /.0OO3 Z3 /.ooos Z3 /00/7 iJ Aooxe ZJI /.0003 Z4 /.OOOQ Z4 /oo/e Z4 /.ooza zs /.oooa zs /oooa zs /.oo/B Zf l.oeso Z6 /.0O03 zt /.OOOS Z6 /.00/8 26 /ooJo Z7 /.0OO3 Z7 /.00O9 Z7 /.oo/e Z7 /.0 030 ze /.0003 ze /.eooe ze /.oo/e ZS /t>030 zs /.0OO3 Z9 /.oooe za /.oo/a Z3 /.oo3l vJO /.00O3 3o /.oeoS 3c /.oo /S v*> /,oo3 1 \3/ /.O0O3 31 /.OOIO 31 /.oo/a •31 /.003I <3Z /.0OO.3 3Z /.oo /o •JZ /.oo/e 3Z /.003I «3» /.0004 33 /.oo/o •33 /.oo/a 33 /,003Z 34 10604 •34 /.OD/O •34 /.ooie •34 /.oa3Z JS /.0004 •jsr /oc/o ,33 /.oo/e 33- /.003Z /.OO04 41 / oo II 41 /.OOZ/ 4t /.oe33 4Z /.OO04 4Z loon 4Z /.eozi 4Z /.eo34 ■*3 /.0OO4 43 /cell 43 /.oeZ/ 43 /M034 A4 /.O004 4-t l.oo// 44 /.OOZI 44 /.0034 4S /.ooos 4S /oo/l 4S /.eozi 4S- 1.0034 ■4^ /.ooos 46 /.oo/Z 4t /.oeZZ 46 /.o»3S 47 /.ooos 47 /.eo/Z 47 /.oezz 41 I.003S 46 /.000.S 48 /.oo/Z 46 /.oeZZ 48 I.0033 43 /.ooos 43 /.oe/Z 4j> AooZZ 49 I.O 03S \S0 /.ooos •So /.oo/Z ~re /■oezz 3o /.OO 36 31 /.ooos 31 /.oo/Z 31 /oeZ3 31 /.eo36 yffX, /XIOOS 3Z /.oo/^' 3Z /.eo Z3 3Z /0 03h ■S3 34 /.ooos /.ooos •S3 34 /.oo /3 /.00/3 33 34 /oeZ3 •33 34 l.003(, /.0037 33- •36 /.ooos /jO0O6 •3S •3* /.00/3 /.ce/3 33 •3i /.eoZa /eoZ4 3S 31 /.eo37 /.0037 37 /.oooC >sr /.oo 13 37 J.oo Z4 37 /.0037 sfS 1.000 i •sa /.oo/-^ •3a /.aoZ4 •fa /.otSB >f^9 i.oooCi •33 /•eo/3 •fS /.OOZ4 /.eo3B £ TABLE U ^EC/fNT T/^BLL - coMTi/iUEO. licvatLeyt Secant Elevation 6ecani Elevation sSecani Elevation \5sconi S- -0 /.ee^6 6' -0 1.003^ 7° '0 A0O7S 3' -O Aoose 1 /.0036 / /.oass / A.ooys A A.0033 Z /.e033 z /.0036 Z A^oo76 X A.OOBa 3 /.0033 4o a 10037 a A.007B a A.OAoX 3 /.0040 a f.DO'SB a A.oo7e 9 AOICZ /o /.004I /o /.cose AO I.OOfS AO AOleZ // /.oe4l // /.oese ll A.0073 lA AOI03 /Z /.004I iZ /.0039 AZ A.00 73 AZ A.0I03 13 /.004I 13 I.O0S3 A3 A.0O60 A3 A.o/04 /■a /■O04Z 14 i.oosa A4 A.eoao A4 AOA04 *s /.004Z jr /.0060 AS A.OOSO AS- Aeie4 /e. /■e>o4Z /6 t.OOio A6 A.ooei A6 A.6A0S n /.0043 17 /.eoio l7 AOOBA 17 A.0JO3 /e /.oo43 /e /.006I AB A.ooBZ. AB A.O/oe 13 /.O043 /3 /.006I A3 A.ooez Aa A^oiei Ze J.O043 Ze /■006I 2o A.006Z Zo A^oio7 XI /.O044 Zl /.eeix Zl A.oofS Zl A.ei07 zz /.OO44 ZZ /oatz ZZ A.ooBJ ZZ A.oitt Z3 /.0044 Z3 /■ootx 23 A 0064 Z3 A.eioe Z4 /■0044 Z4 /.oe is Z4 A.0064 Z4 A.oioO Z5 /.004s Z3 /.ee63 ZS A.oeB4 zr A.OI03 Z6 /.OO-W ZC 1.00 63 Z6 AoeSS Z6 AOI03 Z7 /.004S Z7 A 00 64 Z7 /.008S Z7 i.oi 1 ze /.0046 XB A0064 Z8 A. 008 6 ze A.eii Z3 /.0046 *3 t.0o64 Z3 A.ooBt za A.OII 1 3e /.0046 3e AOOtS 3e Aoe87 So A.OII 1 31 /.oe^6 31 A.ooba 31 /.oeB7 31 AOAll 3Z /.ee47 3Z /•eots 3Z i.oeS7 3Z A.OAIZ 33 /.0047 33 /.eoii 33 A.0068 33 A.cAIZ 34 I.0047 34 1.0066 34 A.ooae At A.OII3 3S- /.004e 33- A0066 •30- Aaoas 3S A-e//3 ^i /.oo4e 36 A.0O67 •36 A.ootS 36 A.OII 4 ar /.eo4e 37 /.O0 67 37 1.0033 37 A^o 1 14 3a 1.0048 33 A0067 3» A.ooae 38 AotiS 39 /.0 043 33 Aoe66 3S A.oeOo 33 1.0 113 4o J.0043 4e /.006a 40 A.O03O 4o I.eli6 ■4/ 1.00 43 41 /eo(B 41 l.oesi 41 A-oilU 4Z /.003-0 4Z A.0O69 4Z l.eeai 4X A.OII 7 43 J.oeso 43 I.OOb9 43 /.ecsz 43 A.oilj 44 /.0030 414 A-ooia 44 A.eeoe 44 A.OII 8 4S- /.ooso 4r 1.007 4^ A.003Z 4i Aoiie 46 Aeesi 46 /.ooje 46 A.ce33 46 AoliS 47 1.00.31 47 A.oofo 41 AO0S3 47 A.eAi9 46 /.oe /.o/3(, Aot^C /.0/37 /.e/37 /.e i3a /.€> /-te /.C/3'9 /.0/3S J.eijgo /.ot.4o 1.0 1 .a I /.OIJl I l.oiJiz /.Of.>ilZ /.O/'t'S /.o/.-t3 1.01^4 /. o /^^ /. o MS /.O/JIS /.c/4h t.o iA(> /.OI47 / 0/47 /.o/4e /.o/4e /.0/43 /.o /40 Ao/SO J.oiSI /.o /«r/ /.O/^Zi /,0/-S'-3 /.OJS3 •0 I.OI.S4 //• '0 /.0/B7 IZ' 'O 1 /.0/i'ff / l.o/BB / z i.ot.sr z /.0/6B Z 3 /.oi.g6 J /.o/SB 3 4 /.o/3^e 4 1.0/99 4 S /.0/.S7 •s /.0/90 .r 6 /.O ISt 6 /.0/9/ £ 7 /.oise 7 I.O/9I 7 6 /.o/^a B /.0/9Z B 9 1.0 /sa S J.O/9Z 9 10 /.o/^S /o /.0/S3 /o II /.0/60 II 10/93 II IZ 1.0/ io IZ /.0/9JI /Z 13 l.oiil /3 /.e/9-f /3 14 /.oitT- /4 1.0/93' /4 /T l.oiCz AS- 7.0/9A /r /(. /.OftJ /6 /.0/3C /b n /.eitS 77 /.o/9f 17 IB /.o/t4 IB 1.0/36 18 /9 /.o/i4 19 l.ei4B 19 ze 1.0 it^ ZO /.0/99 20 Zl /.etL£ Zl /.0/99 Zl zz /.o/il, zz 7.0Z00 ZZ z» 1.0 nt Z3 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AJtiol 33' 1/SZ4 •37' Izszi 41- /.3ZSo 4S' A4I4Z /a /.IS46 10 I.ZS4S 10 A3za4 10 1.4164 2e LISAS Zo /.ZS77 2o /.3jie Zo I.4XX7 Jo /jsaz 3o AZboS ^0 /.33SZ •So I.4Z70 40 /.2o/< .«« I.Zt,33 4o /.33at 40 /.JJS 13 yfi i.7o3a •So IZbbl •Oo /J.^ZI ■So i.jfS^rr War Sapartment, Office of the Chief of Ordnance. September 23, 1922. Bd.500 - 10-2-22. 461/14087. PLATE I PLATE II PLATE III PLATE IIIA PLATE TV PLATE V PLATE VI PLATE VII PLATE VIIl PLATE IX PLATE X Arf^:*-; . ' ■ ■ .iti^-ve^^- J PLATE XI PLATE XI A