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OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT NATIONAL DEFENSE RESEARCH COMMITTEE

DIVISION SIX- SECTION 6.1

PRESSURE DISTRIBUTION MEASURE MEN TS

ON THE

MK 14-1 AND MK 15-1 TORPEDOES

ROBERT T. KNAPP

OFFICIAL INVESTIGATOR

THE HIGH SPEED WATER TUNNEL AT THE

CALIFORNIA INSTITUTE OF TECHNOLOGY HYDRODYNAMICS LABORATORY

PASADENA, CALIFORNIA

·section No . 6 . ·F·sr207~ 2244 Report Prepared by Joseph Levy

Laboratory No . ND-18 1 Hydraulic Engineer

August 15 _, 1945

This document contains information affecti~q the national defense of the United States within the meaning of the Espionage Act , 50 u.s.c., 31 and 32, as amended. The transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law .

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TABLE OF CONTENTS

·sec tion No .

ABSTRACT AND SUMM ARY

INTRODUCTION

APPARATUS AND TEST PROCEDURES

Description of the Torpedoes

Model Construction

Piezometer Openings and Pressure Leads

Di fferential P ressure Gage

Test Procedure

TE ST RESULTS

Presentation

Longitudinal Pressure Distribution - Zero Yaw

Yaw Effects on Longitudinal Pressure Distribution

P ressures Around Cross Sections Normal to Torpedo Axis

Effect of Velocity and ·s tati c Pressure

Calculati on of Forces from Pressure Distribution

CAVITATION AND PRESSURE DISTR IBUT I ON

PRESSURE INTAKES F0R DEPTH CONTROL AND DEPTH AND ROLL RECORDER

Depth Control

Influence of Propellers

Depth and Roll Recorder

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1.

1.

1.

6

6

6

8

8

8

1.0

1.0

1.1.

H

40

42

42

43

43

ABSTRACT AND SUMMARY

This report covers measurements of the pressure distribution around the bodies of the Mk- 1.4 - i and Mk iS i Torpedoes " both when equipped with the standard tail assembly and with a shroud ring tail added , and includes studies of the effect on the pressure distribution of variations in yaw and pitch angles . velocity: and static pressure (i e , submergence) These two torpedoes are both ·21. inches in diameter. made up with heads and aft erbodi es having the same external shape , and both are equipped with identical fin and rudder assemblies The only difference between their external shapes , therefore is due to the different lengths of cylindrical mid-sections . and resultant different overall lengths (The Mk 1.4- i is 2C "S ft long . and the Mk 1.5·- i IS 24 ft long) The tests were maae on 2 -inch diameter models (model scale 1. . 1.0 6)

In addition to providing a general picture of the pressure distribution as affected by the different variables the data pre-sented herein are useful in determining the best locations and arrangements for the pressure intakes to the immersion mechanism and to the depth pnd roll recorder , and also as a check on cavi tation measurements Because the pressures on the fins themselves were not measured in these tests . the data cannot be used to calculate the overall forces acting on the complete torpedo

The main observations and conclusions are summarized in the following paragraphs

i' Within the range of these tests the pressure. distribU··· tion. as presented in terms of p/q was found to be independent of variations in velocity and static pressure or submergence That is. the difference between the pressure at any station on the body and the static pres sure of the undisturbed water is independent of tne static pressure and is directly proportional to the velocity head

2 The addition of the shroud ring around the fins of these torpedoes has no measurable effect on the pressure distribution

3 . The pressure distributions around the head and afterbody of the Mk 1.5 i were found to be practically identical with those of the Mk i4 · i That is . increasing the len~th of the cylindrical mid - section does not, in this case affect the pressure distribut1on on the head or afterbody

4 The pressure on the surface .of these torpedoes equals the st"atic pressure· of the undi;sturbed water at two positions" one on +he projectile nose and one on the afterbody (See Figures 1.2 . 1.8 24. and 30) ·Ahead and behind these

J DfHli J A!- .·

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two stations the pressure is above staticJ while between the two (which includes about 83% of the over-all length of the Mk i4-iJ and 86% on the Mk iS-i) the pressure is below static .

5 . The position on the afterbody at which P = P0

is only slightly affected by yaw or pitch angles up to 3° .

6 . On the basis of these measurements .. made without rotating p ropell ersJ it appears that the best arrangement for the pressure intake to the immersion mechanism would be through a piezometer ring connecting to four pressure taps uniformly distribut~~ about the circumference of the afterbody and about 3:: inches ahead of the end of the tail . The pressure imposed on the diaphragm would then be equal to true hydrostatic pressureJ and practically independent of yaw or pitch The influence of the propellers may shift this point slightly eithe~ aft or forward .

7 . Placing the pressure take-off for the depth and roll recorder where P = P

0 on the nose is not recon@ended be

cause P changes rapidly in this zone and large error,s can result from small inaccuracies in locating the connection . Connection of the depth and roll recorder to the point of the afterbody where P = P

0 is _, of courseJ

physically impracticablE: . It is recommended .. therefore _, that the pressure intake be left unchanged and_, if necessary , determine the corrections to be applied to the dep th record .

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PRESSURE DISTRIBUTION MEASUREMENTS

ON THE

MK 14- 1 AND MK 15- 1 TORPEDOES

INTRODUCTION

This report is the second in a series covering Water Tunnel tests on the United ·states Navy Torpedoes Mk i4 , Modification i, and Mk iS, Modification i' -The first report(i) included force and cavitation measurements on the standard torp~does and on these torpedoes when equipped with a proposed shroud ring tail. The tests reported herein were made to investigate the pressure distribution about the bodies of these torpedoes , both with the standard tail and with a shroud ring tail, and to study the effect on the pressure distribution of variatjons in velocity, static pressure (submergence) ) and orientation with respect to the line of travel . The tests were made on 2-inch diameter models in the High Speed Water Tunnel at the California Institute of Technololgy, and were authorized by Dr.. E H. Colpitts , Chief of Section 6 ._ ii, National Defense Research Co~ittee .. in a letter dated July i2 , i944 .

The data presented herein are useful for determining the best location for the pressure intake to the depth control (immersion) diaphragm, and for determining whether the location of the depth and roll recorder is such as to enable the device to indicate actual running depth . The data may also be used to check the cavitation characteristics of the torpedoes .

The tests made included measurements of the pressure distribution about the Mk i4-i and Mk iS- i Torpedoes with standard tail J and also with tail fitted with the proposed ring tail , under cond i tions of constant velocity and constant static pressure ) and with varying yaw between -- 6 and +6 degrees Additional tests were made to determine the effect 0 if any _. of variations in static pressure and velocity on the pressure distribu~ion

APPARATUS AND TE ST PROCEDURES

DESCRIPTION OF JHE TORPEDOES

The Mk i4 and Mk iS series torpedoes are all 2i inches in di ameter ) made up with heads and afterbodies having the same ex t e rnal shape , and al ·l are equipped with identical fin and rudder ass emblies The only differences in their external shapes , theref o r e . a:re due to the different lengths of cylindrical mid-sections ,

( 1 ) 11 Force andCavitation Tests of theMk ~ 4 · -1 and Mk 15·- 1 T orpedoes"

by Joseph Levy , NDRC Section No 6 1 " sr~o7~~ ~38 , July ~5, 1945

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and resultant different ove:r-all lengths, of the various modifications of these two groups. To reduce the bulk of the work it was decided to make the~e tests on only one torpedo in each of the two ']roups. The Mk i4, Modification i, and Mk iS, Modification i, were selected because it was understood that these were the most frequently used. The general outline, overall dimensions, and weights and displacements of these two prototype torpedoes are shown in Figure i. Figure 2 shows the fin and rudder structures,

MK 14-1

WEIGHT READY FOR WAR SHOT 3185 ± 20 LBS.

WEIGHT . RE.ADY FOR E.XERC.ISE SHOT 3071 ± 2.0LBS.

OISPLACEME.NT ~T 64 LBS jcu. FT~ 2.510 LBS.

WE.TTE.O SURFACE. 103.3 SQ. FT.

DISTANCE. TO C. G. READY FOR WAR SHC\T 105.1 124.8.

READY FOR EXERCISE SHOT 107 . .5 124.8

M..l:S....&::.. 3B47 ± 2.0 LBS .

384"1± 2.0 LBS.

304.!5 LBS.

122..5 SQ. FT.

HORIZONTAL FINS AND 1'\UOOE.RS

/ 0 0 0

DIST. TO CENTER OF BUOYANCY MK 14-1 109.5 .. VE.RTiii:.AL FINS AND RUOOE.P.S

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MK 15-1 130.2."

OVERALL LENGTH MK 14-1 2.46

MK 15-1 2.88"

FIG. 1 - MK 14-1 AND MK 15-1 TORPEDOES PRINCIPAL DIMENSIONS AND WEIGHTS

Jr l ~gli I

HORIZONTAL FINS t: RUDDERS VE:RTIC.AL FINS E; RUDDE:RS

FIG. 2 TAIL SURFACES OF MK 14-1 AND MK 15-1 TORPEDOES

Figure 3 shows the shroud ring installed. and the profile of the proposed shroud · ring is shown in Figure 4. The location of the pressure taps is shown in Figure s.

RINC. IN AFT POSITION

TRAILING EDGE OF SHROUD RINu COINCIDES WITH CENTERLINE OF VERTICAL RUDDER POST

FIG. 3- TAIL OF MK 14-1 AND MK 15-1 TORPEDOES SHOWING LOCATION OF SHROUD RING

5

------

-IN 2° TO AXIS OF TORPEOO

Q

l_

FIG. 4- PROFILE OF PROPOSED SHROUD RING

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("'> ("'>

0 0 ::z z: , , - -0 0 1"'11 m z: z: --f --f - -)> )> I I

.925L

I ~---------------------------- OVER-ALL LENGTH • L-~--- t

MK 14-1 TORPEDO MODEL

· -.119L .821L .936L

~B"""""~'E~~~ll~f ' ' ~~ ~ '' ~ ~ 'r;;ttJJ ' ' ''PjLJ~ ~ 0 . I ~r . 3

~----------------------------------0/ffi·A~ L~GTH•L.-------------------------------~

MK 15-1 TORPEOO MODEL

F i G, 5- SHOWING LOCATION OF PRESSURE TAPS

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FIG, 6- MODEL OF MK 14-1 TORPEDO WITH STANDARD TAIL

FIG. 7- MODEL OF MK 14-1 TORPEDO WITH RING TAIL

FIG. 8 - MODEL OF MK 15-1 TORPEDO WITH STANDARD TAIL

FIG. 9- MODEL OF MK 15-1 T0no cu O WITH RING TAIL

MODEL CONSTRUCTION

The stainless steel models used i n these tests are sh o wn in Figures 6 to 9J incl.usi v eJ and have a maximum diameter of two inches (mo del scale rati o i t o iO. 5 ) . Since both prototypes have identical heads and afterbodiesJ it was necessary to make only one model head and one model afterbody. A removable length of cylindrical mid-sect ion provides for the change in over-all length in going from one model to the other. Two inter-changeable tail cones were providedJ o ne with fins and rudders but without shroud ringJ and one with shr o ud ring. The rudders on both tail cones are fixed in neutral positi o n. The f o rebody, afterbody, and tail c o nes were s o made that each part could be rotated about the longitudinal axis independently o f the other parts. With this arrangementJ a single row of piezometer openings distributed along a meridian is sufficient f o r exploring the pressure distribution about the entire body. A protract o r scale scribed at the joint line o f each body secti o n, graduated in 5-degree intervalsJ provides the means for setting the angular position of the piezometer taps.

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PIEZOMETER OPENINGS AND PRESSURE LEADS

The piezometer openings were made by drilling i/i6-inch holes at ~ight angles to the surface before making the final finishing cut on the outside . Each hole was then plugged with a stainless b[eel rod extending about 3/i6 inch into the body . A brass tube of i/i6-inch outside diameter and i/~2-inch inside diameter was inserted in the hole from the inside and silver-soldered in place . A finishing cut was then taken over the entire surface an~ a i/32-inch diameter hole was drilled through each plug and its lip was reamed to a 0 . 005-inch radius . Twenty-two such openings were provided on the Mk i4-i model ; and ' 23 on the Mk iS- i model. As will be seen in Figure 5; Tap i4 is located in the mid-section piece which is used with the Mk iS-i model alone

Rubber tubes were used to connect these brass tubes to a bundle of nickel-silver tubes extending from the outside of the Water Tunn ·el; through the model supporting strut ; and into the model through an opening in the bottom of the center section . Th P slenderness of the strut limited the number of tubes that could be carried through it to i2 . It was· necessary; therefore, to measure the pressure distribution about the forebody and about the afterbody in separate test runs . Outside the working section, each tube terminated in a valve mounted on a common manifold , so that each piezometer tap could, in turn, be connected to the differential pressure gage . Figure iO shows the model of the Mk i4-i mounted on the streamlined strut, with base plate and tube manifold, ready for installation in the tunnel .

DIFFERENTIAL PRESSURE GAGE

The differential pressure gage used in these tests consists of two opposed piston and cylinder units and an automatically we i ghing beam type balance . The two opposing ·pist.ons are interconnected with a yoke system which also connects to the beam of the balance . Thus; the force transmitted to_the balance is proportional to the difference betwe e n the pressures applied against the two pistons . The cylinders are continuously rotated by an electirc motor to overcome static friction . •Another motor ; controlled through a photo-electri : cell by the rise and fall of the balance beam; shifts a rider weight along the beam to balance the applied force . A veeder counter connected to the rider drive is geared to read the differential pressure directly in pounds per square inch to O . OOi psi .

TEST PROCEDURE

The pressure distribution around the torpedo was explored by setting the piezometer openings at a given angre and measuring the

f + + p~eRsures at each tap for YO'•' anqles o 0 ; - 3; and - 6 degrees . For the Mk i4-i; the piezometer tap settings were varied from 0 to 90 degrees in iS-degree steps . Because of the symmetry of the torpedo; these measurements give the pressure distribution about the entire body . For the Mk i5- i ; measurements were made for pressure tap settings of 0 ; 45 ; and 90 degrees only Most of the

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-7-

FIG, 10- MODEL OF MK 14-1 TORPEDO ASSEMBLED ON STREAMLINED STRUT WITH BASE PLATE AND TUBE MANIFOLD

READY FOR INSTALLATION IN THE TUNNEL

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tests were made with a constant velocity o f 40 feet per seco nd and constant static pressure in the tunnel wo rking section of 10 psi. Several test runs were made with dif f erent velocities and static pressures to determine the effect o f these variables on the pressure distribution.

The static pressure I'"eference was taken at the tunnel wall at a point 3 model diameters upstream of the mo del no se. The differential pressure measured at each piezo meter opening was corrected for tunnel pressure gradient by subtracting fro m it the tunnel pressure drop~ measured in the absence o f the model~ between the reference p o int and a point o pposite that piezometer o pening.

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TE ST RE SULTS

PRESENTATION

The test results are shown in Figures i2 to 39 J inclusiveJ and are presented in terms of p/qJ where

p

p

p- p 0

normal pressure on the surface of the torpedo J pounds per square foot

P 0 = static pressure in undisturbed water at same level as torpedo center lineJ pounds per square foot

2 q i/2 P V = dynamic pressure of waterJ pounds per square

foot

p mass density of waterJ slugs per cubic foot

V =mean relative wate r velocityJ feet per second

The tests reported herein includeJ in effectJ measurements on four bodies: (i) Mk i4-i with standard taiL (2) Mk i4-i with ring tailJ (3) Mk iS-i with standard tailJ and (4) Mk iS-i with ring tail . The test resultsJ howeverJ show practically i d entical pressure distributions around the four bodies . That isJ increasing the length of the cylindrical mid-section does not affect the pressure distribution on the head or afterbody . AlsoJ the addition of the shroud ring does not alter the pressure distributio~ Figure ii is a composite curve showing the longitudinal pres-sure distributionR at zero yaw on the heads and afterbodies of the four torpedo shapes tested . At th.e top of the sheet is a half outline of the head and afterbody used with all Mk i4 and Mk iS series torpedoesJ drawn to scale . Distances are measured from the nose and from the tail toward the center in inchesJ prototyp e dimensions The points plotted on the curve are a~erage points for each pressure tap taken from Fig·ues i2J i8 J 24J and 30 . It is seen t•hat the pressure at each tap is practically the same for both the Mk i4-i and Mk iS-iJ whether witho•ut or with the ring tail .

The longitudinal pressure distribution curves presented hereafter are organized in four groupsJ one for each of the four bodies tested . In the following paragraphsJ reference will be made to the figure numbers showing curves for the Mk i4-i with standrad tail (without ring) . The figure numbers given in parentheses refer to the corresponding curves for the three other bodies .

LONGITUDINAL PRESSURE DISTRIBUTION - ZERO YAW

In Figure i ' 2 ( i8J •24J 30) is shown the longit >Udinal pressure distribution around the torpedo at zero y 'awJ plotted against distan c e from the tip of the nose divided by the overall length . I t is evident thatJ for a symmetrical body oriented with its axis

CON F I D E'NT I AL

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LENGTH ... [>------- CYLINDRICAL

e~-~~_&_: ____ ,j l

16 20 21

p q

1.0

Q8

0.6

D.4

0.2

D

-0. 2

-0 .4

OVER-A~ _ LL~EN~G~TnH_~M~K_1~4~-1~~2~46;"r-----------------• -~ MK 15· 1 288"

\ \

I I I

I o MK 14~ STANDARD + MK 14-1 RING TAIL

" MK 15·1 STANDARD

• Ml< 15-1 RING TAIL

I

DISTANCE FROM NOSE, INCHES DISTANCE FROM TAIL, INCHES

20 40 60 100 8 60 40 / .. ... ~ r-- l ............ / I

~ f '\.

...

FIG~ 11- MK 14-1 AND MK 15-1 TORPEDOES

LONGITUDINAL PRESSURE DISTRIBUTION ON HEAD AND AFTERBODY

YAW ANGLE = 0°

I

---*2 a-

parallel to the direction of motionJ the pressure around any section normal to the axis should be constant. It is seen that the seven points plotted for each pressure tap on the Mk i4-iJ and the three points per tap on the Mk iS-iJ indeed show very little scatterJ except for Tap No. iS on the Mk i4-i. This tap is immediately behind the joint between the center-section and the afterbodyJ as may be seen in Figure s. Apparently the after edge of the center section had been roughened slightly fr om continued useJ and this r o ughness affected the pressure readings at Tap iS.

From full stagnation pressure at the tip o_f the noseJ t he pressure drop s rapidly t o abo ut 0.36 q below static and then rises againJ but remains below static pressure over almost the entire

I I 0

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l ength of the torpedo . Where the afterbody begins to taper down there is a furth~r decrease in pressure followed by a rise to above static pressure slightly ahead of the leading edges of the fins . The ~ pressure on the body equals the static pressure (P = P)

. 0 at two stat1ons~ one on the nose and one on the afterbody

A comparison of the data of - Figures i2 , i8 , ·24 , and 30 was made in Figure ii to show that the pressure distributions about the four bodies tested are nearly identical . The same result will be obtained by comparing other groups of four corresponding drawings li·sted in the following. paragraphs

YAW EFFECTS ON LONGITUDINAL PRESSURE DISTR I BUTION

Figure i3 (i9 , ·25 , 3i) shows the longitudina~ pressure distribution on the body as it is affectPd by yaw or pitch . These curves show the pressure along a longitudinal sect io n at right angles to the plane of yaw or pitch .. , From a cons ideration of the symmetry of the body , it is evident that the pressure 9istribution along the top and bottom meridians when the torpedo yaws to either starboard or port , is exactly the same as th9 pressure distrrbution along the sides (on the horizontal meri dians) of the to rpedo as it pitches up or down .. ;It is seen that the effect of yaw or pitch is to lower the pressure over the entire length , only slightly for angles below 3 degrees , and more notic!ilably for larger angles .

In Figures i4 (20, ·26 , 32) and iS ('2i , •27 ., 33) is shown the longitudinal pressure distribution on the windward and lee sides of the body, respectively , along meridians at 4t degrees with the planes of yaw or pitch . It is seen that yaw causes the pressure on the nose to increase on the windward side an·d to decrease on the lee side . Along the mid- portion of the hull , the pressure ~n both sides decreases slightly with yaw, and on the afterbody taper the pressure decreases with yaw or pitch on the windward side and incteases on the lee side In the vicinity of the tail fins (at Taps 2:2 and ·23) J the pressures are affec·t .ed by the fins , and on the lee side the direction of change in pressure due to yaw is again revers.ed ..

Figures i6 (2:2J 28 J 34) and · i7 ( 2) J ·29 , 35) show · the longi tudinal pressure distribution along thb windward and lee sides of t~e body, respectively , along a section in the plane of yaw or pitchJ i . e .. , along the top and bottom if pitching, and along the sides when yawing . It is seen that on the nose, the pressure again rises on the windward side and drops on the lee side when the torpedo is yawed Along the cylindrical portion of the hull , the pressure on the windward side increases with yaw .. and on the lee side it is practically unaffected by yaw ..

PRESSURES AROUND CROSS SECTIONS NORMA L TO TORPEDO AX I S

In Figures 36 to 39 ; inclusive J are, presented the transverse pressure distributions around cross sections taken . normal to the axis of the torpedo at each piezometer opening or station The

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curves show the pressures for yaw angles of 0, 3, and 6 degrees , plotted against body angles measured toeither side from the verti cal center line Again, from symmetry considerations, it is evident that these curves give also the pressure distribution when the torpedo is p~tching, if we measure the angles from the hori zontal center line instead of the ~: v~rtical Also the angles may be reckoned from either end of the center line (i e ., either from top or bottom, or from port side or starboard side) since the pressure distribution is symmetrical about the 90- degree points on windward and lee sides Figures 36 and 37 cover the stations on the forebody Figure 38 gives the pressure distribution on the afterbody with standard tail and Figure 39 on the afterbody with ring tail A comparison of these last two figures again shows that the presence of the shroud ring has practically no effect on the pressure di strib ut ion

The data presented in these figures were taken on the Mk i4-i model Similar curves for the Mk iS-i cannot be plotted because the meas,urements on · this model were made only with the piezometers at 0, 4S , and 90 degrees from the vertical However the data available on the Mk iS-·-i show that the pressure distri bution about it is practically the same as about the Mk i4 i These curves, therefore, may be considered as applying to the Mk iS·- i also , that is , the curve given for any station on the Mk i4 ~ applies also to the station having the same numb er on the Mk :iS - i

It will be noted that ·stations i ; 1. 3 . and i4 are · not shown on these curves ·station i is at the tip of the nose . ·station i3 is on the fixed center sect·ion which could not be rotated; and Station i4 is on the length of cylindrical body section which wa~ used with the model of the Mk iS-i but not w1th the Mk i4- i

EFFECT OF VELOCITY AND STATIC PRESSURE

The tests presented thus far were all made with a water velocity of 40 feet per second and a static pressure in the work ing section of the tunnel of iO pounds per square inch Another series of tests were made with velocities of 25 30 and SO feet per second and static pres~ures of S. iS and 2S pounds per square inch These tests showed lhat r · within the range investigated the velocity and static pressure have no measurable effect on the pressure distributio n

CALCULATION OF FORCES FROM PRESSURE O! STR I BUTION

with the pressure distribution about a proJectile completPJv known 1t is possible to calculate from the pressure distribution data the form dro.g (but not skin friction drag)_ the cross force and the moment acting at any yaw angle by proper integration of the distributed pressure forces These tests however were all made on bodies with tail surfaces ~nd the pressures on these surfaces themselves were not measured because of the thinness of the plates Therefore . the forces acting on the torpedoes cannot be calculated from the data presented herein

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p q

1.0

08

0 .6

0.4

02

0 0.1

,..-

\

\ J -0.2

~ -0.4

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02

-

- i2-

DISTANCE ALONG AXIS X OVERALL LENGTH = 1:

03 0.4 0.5 Q.6 0.7

-. ............. --

FIG. 12· - MK 14-1 TORPEDO (STANDARD)

PRESSURE DISTRIBUTION ALONG LONGITUDIN AL SECTION

YAW ANGLE = 0°

08 ~ ID

v

p q

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10 II 12 13 15 16 17 18

LOCATION OF PRESSURE WS

O.Bfi---+---~---t----t--------~--+---4---~---t---4--~~--+---+---~---+---+--~~--~~~ I

i I

I I I o .~r--t---t--~----T---+---4----r---t---4----~~ ---t---+--~'~--+---+---~~~--~--+---~--~

!I i ! I I I

I I I 0.4H---+------t----t----t-·-t--,-l--+--+----t-----i-

i I i I

I i' i II

I I 0.2t-t--t--+--+--+-+-~-+--+---+-______;_--4- +-+--+--+--4--4---1--1-------i

I I I I I I ~ST~~AL~L~~G~IS = t

0 ~t-t-__ 4o~~---r--~of.2~-i--~or3---t--~o~.4~--lr-~ar5~_,---;as~--.-~o~~~-4--~a~e---7.~~~~~9~--~~~n ......--::-~-... -_+---:tt.-=±:-: __ ~b,. :=-=t! =--+~~H--_.J~l.:;.j.._,_~+----1---~"'"'~-"-.l_~l--. I 1/ ,

-0.2

~ - 0.4t-----+--"...__-+-----+----1

F IG. 13- MK 14-1 TORPEDO (STANDARD)

PRESSURE DISTRIBUTION ALONG LONGITUDINAL SECTION

AT RIGHT ANGLES TO PLANE OF YAW OR PITCH

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•

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p q

1.0

0.8

0.6

04

02

0

-02

- Q4

Ol

I

~\ ~ . ~,

\t J

'~:,ll 1\!'l

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10 II

02

·-

-14-

12 13 15 16 17 18

LOCATION OF PRESSURE VIPS

'

DISTANCE ALONG AXIS : X OVERALL LENGTH L'

03 0.4 05 06 0.7

-~ r-- : f'"""-=-r=-~~ r::-..n• YAW OR P

I tfcH 'rGLES -- ~"

FIG. 14-M~ 14-1 TORPEDO (STANDARD)

PRESSURE D(STRIBUTION ALONG LONGITUDINAL SECTION

AT 45° TO PLANE OF YAW OR PITCH

Windward Side of Body

20 21

Q8 ~-=-- 1.0

k1 l?' ......

r=~f ~";.'

1.0

a 8

0. 6

Q 4

2 I I

Q

i 0

t 0.1

~ ~

\ (f 2

,, \\\ J it

-Q

~· V1 I .. :;~ -Q

-iS-

10 II 12 13 I~ 16 17 18

LOCATION OF PRESSURE W>S

I I I

I

'

I

DISTANCE ALONG AXIS • ..! OVERALL LENGTH L

02 0.3 0.4 0.~ 0.6 C7 r#'

~ r::.::- .~: ll.:f.: :a==- r-=---- - - ..:;w;:: -=-=--:1!! .:...--- .__ ·~·

~

YAW )R PIT H AN fl.ES')

FIG. 15- MK 14-1 TORPEDO (STANDARD)



Lee Side of Body

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20 21

I I I I

I

08 d 1.0

.4 ~ -.. -

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CONFIDENT lA~

10

1.0

I

\ 0.8

~ ~I ~~ I\ I~ I

Q6

II

I I

0.4 I'

0. 2

I

I I I

1\ I I

p q

0 .. 0.1 02

\4 . ---!: ::1.: r-::-.: -lp lo I

'i \\[\

2 I

\I',' r/,' \ I

I

.Q

f\1 -0 .4

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-i6-

II 12 13 15 16 17 18

LOCATION OF PRESSURE lliPS

I

i

-

I

I DISTANCE ALONG AXIS = X OVERALL LENGTH L"

0.3 0 Q4 0.5 0.6 0.7 OB t:r.:- - '~ 1~-- - - .::!": r--=-= l :i=-- l4 --- -0" :q, -, i ......

~ '-

_} _YAY OR P TCH ANGLES .... t-.;-N

__ j___L I



IN PLANE OF YAW OR PITCH


~.9 I.

~ ...

.! q

1.0

o.a

as

04

0.2

0

-02

4 -Q

10

II

i I

\

0.1 0.2

I~

• rr \ ; / y w· OR

·~.\ / v

j

~I ~-I/ '"?"

-i7-

I I 12 13 15 • 16 17 18

LOCATION OF PRESSURE W'S

I I I I

I I

I I I

I DISTANCE ALONG AXI§ • ~

OVERALL LENGTH L

0.3 0.4 o.5 0 .6 07

~ ~

PITCH ANGL£~

FI G. 17 - MK 14- 1 TORPEDO (S TANDARD)



Lee Side o f Body

CONFIDENTIAL

08 ~9 1.0

~ ~ ... t-"

CONFIDENTI AL

CONFIDENTIAL

t O

08

0.6

Q 4

a

_£ · q

2

0

-0

0.1

/' 1/

\ I

\ IV

CONFIDENTIAL

10

Q2

-

. ----'--

-i8-

II 12 13 15 16 17 18 LOCATION OF PRESSURE W'S

DISTANCE ALONG AXIS X OVERALL L!:NGTH : "'[

0.3 Q4 Q!S 0.6 07

• .......... ......_

FIG. 18- MK 14-1 TORPEDO (WITH RING TAIL)


Yaw Anqle = 0°

00 21

08 ~;- 1.0

v v

..l! q

1.0

0.8

06

0. 2

0

- Q 2

-Q 4

\

-19-

6 7 8 9 10 II 12 13 1!1 16 17

DISTANCE ALONG AXIS X OVERALL LENGTH = "L

0.1 ( .2 03 Q4 0!1 0.6 07

....-::f. -~-7"4 .

~ j

~

~ --- r-- - ·-- r--~ ~~ -- ·~-- ---~ ~ -- - - --~-- ... _..a,

YAW ORP1 CH A jiGLEs ~ ~~1. -

FIG. 19 - MK 14-l TORPEDO (WITH RING TAIL)



CONFIDENTIAL

20 21

0!1 As 1.0

lL 17

~,

~-:'7

CONFIDENTIAL

CONFIDENTIAL

6 7 8 9 10

I.C

0.6

0.4

0 0.1 0.2

1_......,. ·~ ,,

, ~~- A l\\1/

f\:1 · 0. 4 t---

CONFIDENTI AL

-20-

II 12 13 " 16 17 18 19

LQCAJJON OF PRESSURE TAPS

I

I

I QlljTA tj!6; Ab~~ AXIS

= + OVERALL LENGiH

Q3 Q4 0 .5 0.6 Q7

•c..--::. - - -= F-"""' .......... - -- (j' .. -·--T· } .. ' ~"'"·'I:~

AN~ES _/ ... ~

YAW r PITi ~

FIG. 20 - MK 14-l TORPEDO (WI TH RING TAI L)



Wi ndward Side o f Body

20 21 22

f----

_qa L.;~ i

4 '7 ...

~ ~ ... ;/

.f q

1.0

oe

06

04

a 2

0

-0 2

-0.4

6 7 8 9 10 II 12 13 1!1 16 17

I-'

I !

\ DISTANCE ALONG AXIS X

OVERALL LENGTH = l. 01 0 .2 0.3 Q4 05 06 0 .7

0

L:f ._::=.::i --- I :C..~ t{--- f-1--- - r--=- --=-=-- - ;-.,..__ -- •'IIi

~•\ VI" \, .... I !-YAW ~ PIT~ ANGLES

I

~\ \', 1

~r:-11 ... 7


PRESSURE DISTRIBUTION .ALONG LONGITUDINAL SECTION

AT 45° TO ~LANE OF YAW OR PITCH

Lee Side of Body

CONFIDENTIAL

20 21 22

OB ~ 1.0

...11/l v p-

CONFIDENTIAL

CONFIDENTIAL -22-

34~678 9 10 II 12 13 16 17 18 19 20 21 12~------------------~~~~~~~~~L-------------------------~=-~L_~

p q

1.0

08

Q6

\ Q.4

~ ,

02 ~ 1\ I

1\ ,, 0.1 I

'~ -· ~ I

0

\\1\ ' ·~ ~~''!f \ .. /

-Q2

IV -Q4

CONFIDENTIAL

;

I

I DISTANCE ALONG AXIS X

OVERALL LENGTH .

L Q2 0.3 04 05 0.6 07

""":r- _:.-::-= =F-- ----~-:. ~-~ ~-.s: t-:;~::-: ~-=- -.~ -.-v

' ""'"'-IIi ~

~NGLES~ "" YAW OR PITCH

FIG. "22- MK 14-l TORPEDO (w)TH RING TAIL)




08 ~9 10

k,j ~ ~-

! q

I.

~

·-

~

a

0

Q

0.4

i l

~ fa i~

l\' \\

~

6 7 8 9 10

0.1 0.2

I#" """"'

" I

~ p

-23-

II 16 17

·- - -

Ql~!;l ALON!i A!!§ ~ .X, OVERALL LENGTH L

0.3 0.4 0.!1 0.6 0.7 ___ ...,.., -.... -~ ..

YAW 01 PITCi. ANGI ~~

FIG. 23- MK 14-l TORPEDO (WITH RING TAIL)



Lee Side of Body

CONFIDENTIAL

20 21

08 ~~9 ID

6':..s~ ~ Fr r""

CONFIDENT IAL

£ q

CONFIDENTIAL

1.0

oe

0.6

04

0.2

D. I 0

0.2

v-f

\ I -02

\~ -0.4

CONFIDENTIAL

-24-

16

DISTANCE ALONG AXIS = ~

OVERALL LENGTH l 03 0.4 05 0.6 0.7

--........



Yaw Angle = 0°

19 20 21

0.8 ..s;,._- I 0

/ v

......_ ~

! q

1.0

08

06

04

02

0

-02

-04

0.1

~ ~--

g v

A

'V''

0.2

- -+-----

-25-

16

'

DISTANCE ALONG AXIS = ;(

OVERALL LENGTH T 0.3 0.4 05 06 0.7

d' - - · - "3 ..... -~- - - - 1 ........ . :1 --•]1 -~ l-4--

o-\fY:W -~ ·i- "'-'

OR PtTCH ANGLES .

FI G. 25 - MK 15-l TORPEDO (STANDARD )



CONFIDENTIAL

19 20 21

I 08 Q~ 0 ~

.A v

~ ~,

CONFIDENTIAL

.1! q

CONFIDENTIAL

LO

0.8

Q6

Q2

~ Q l 0

.. ~-f

-0.2

h ~

-Q4

CONFIDENTIAl

0.2

-

-26~

16

i

DISTANCE ALONG AXIS = .!!. OVERALL . LENGTH L

0.3 0.4 05 05 0.7

I I d' - ----~---= - - -r----,--- -r:. ~:--~ -~ l --

YAW OR PITCH ANiLES ~

I I .

FIG. 26- MK 15-l TORPEDO (STANDARD)



Wi ndwa rc1 Side of Body

19 20 21

I

I OB Sl~ 1.0

~/ -~

./ ,

?'

"'~ '-&:.: _,II'/ :;_.....oo

'

1.0

0.8

0.6

0.4

I

' 0.2

' I

0.1 0.2 0

I

~ f---- p....:..

I} \\ w

~\ II

'

- 0.2

\\\ Jj ~· \.~;!

-0.4

-27-

16

OISIA~CE ALQ~Ii Al!IS = .X OVERALL LENGTH L

0,3 0.4 0.5 0.6 0 .7

rf -- - -- --r - 3~/ 6 ... = - ~- -- ~~ .. I '- YAW

_I IR PIT! ANGlES I

F IG. 27 - MK 15-1 TORPEDO (STANDARD)

PRESS URE DISTRIBUTION ALONG LONGITUDINAL SECT ION


Lee Side of Body

CONFIDENTIAL

19 20

0.8 !l~ 1.0

/ , I

I

CONFIDENT IAL

CONFIDENTIAL -28-

I~ IS i4 I~ I~ LOCATION OF PRESSURE TAPS

.!. q

~ .QI~;t,AE~'iELL "t~~HAXIS = t Ol-~~--~o~.~--·~--~0~2~~--~a~3~~~·~--~o.~4--~==~a~5~~~~~--;-~o17 __ ~---4aa~~-~~~~~~---liD

~~~-:~-~~~-~-r-----~i~-~~ \M---r--'t-F---~~---~~~~~·-T~~~=~~~~~~·~~- ~~~~

-04~--~--~--~--

CONFIDENTIAL





.f q

0

0

Q

0:4

0.2

0

- 0. 2

-04

.

.

.

-

i

I ' 0 .1 02

i! ~ !I I

I

~

~~\ t 1 ·-

\\\ b ~ -...;:~

CONF I DE NT I AL -29-

16 19 20 21

- -

I

---L---· -

I

I -J--

I

! ...

I :

I

i

; !

i

j

I CISIA!!I~E AW!!Ili AlliS = .X

OVERALL LENGTH L

Q3 04 05 06 0 .7

-~ ..

YAY/ ·oR f-..--PITCH ANGLES-

l I I

F I G. 29- MK 15-l TORPEDO (STANDARD)



LeE. Side of Body

I

i I j -

I I

! I

! I

! I i

--

Q8 .,t/1 lO

! _~ r 6"

lv-,-

CONFIDENTIAL

CONFIDENTIAL

10

1.0

0.8

0.6

Q4

Q2

0 0.1 02

v-I

\ I -0.2

~J -0.4

CONFIDENTIAL

II

0.3

I 'I PRESSURE TAPS

tliSIA!!I!<E ALQI!I!i Al!IS OVERALL LENGTH

0.4 05 0.6

=

16 18 19 zo

X L

Q7 Q8

""" / .........._ ~


PRESSURE DISTRIBUTION A LONG LONG I TUD I NAL SECT I ON

Yaw Angle = 0°

-Ar- 1.0

v

£. q

LO

Q8

0.6

0.2

0

-0.2

--0.4

OJ

~-

0 .-r

~

\~~

-3:1.-CONFIDENTIAL

10 JJ 16

I

I I

:

r- -

r--

OJSTANCE ALONG AXIS X OVERALL LENGTH

. "L a~ 03 0.4 0.5 06 0.7 Q8 .A 1.0

0' /-if' ~---- -· --- ~- - ·-: - - -~- - ..:~ -~ -_ -=:. -~3l:---~----- foo- ~

1 YAW ~R PITCH ANGLES-~ I I I I

FIG. 31 - MK 15-1 TORPEDO (WITH RING TAIL)



- ~~ -11'

CONFIDENTIAL

CONFIDENTIAL

10 II

-.:n-

14 PRESSURE TAPS

16 18 19 2.0

lOt---,----,---,---.---,~--.---~--,----r---.---,---.----.---~--,----,---,---.----r---.

00~--+---~--~---+---4----r---+---T----+---+---1---~---+--~----~--+---~--~---+--~

~ ---4---1--~----~--~--r--- t----+---+---1--~--~----r---r---+---+---,_ __ ,_ __ ~

06~---+---1----1----+---4----~--+---+--- ~--+---~---r---+---+--~r---t---1-~-r---+--~

04~--+---~--~---+--~----~--+---1---~---+---+--~----~--+---,_--~---+--~----~~

0.2~~+---4---~---+---+----~--t---+---,_--~---+--~----~--t---+---~---+---+--~r---l

- 04~--+----r---4-----1

CONFIDENTIAL


PRESSURE 0 I STR IB UTI ON ALONG LONGITUDINAL SECTION



.l q

1.0

08

0.6

04

02

0

-02

-04

I

I

'I

~

l ~

01

i ~

i! (/ II

1\\ ~\\ \\. ~ '..: r;t

-33-

10 II 16

I

DISTANCE ALONG AXIS =

_!_ OVERALL LENGTA L

0.2 0.3 0.4 05 06 07

o• I

F=~ r-:z- - r--- Fr"T-- -1= ·--r= ~·- ~ ... , ~..,_,..

~~

\...YAWl OR PiTCH ArLES

F IG. 33- MK 15-l TO RPED O ( WITH RING TAIL )


AT 45° TO PL ANE OF YAW OR PITCH

Lee Si de of Body

CONFIDENTIAL

OB ~ I. 0

. .r~ ~

~ ~

CONFIDENTIAL

CONFIDENTIAL

.!!. q

1.0

08

06

02

0

-02

-04

£'6'7 h § I

~ :· ~ . •• !I ~ :, ,. 'I 0.1

:4 -~~ •' '• . f. v ·~ \\ r-/: I

~~

CONFIDENTIAL

l'o I' I 16

I

I I. I

. I

i I

! I

i I I

! ! I !

I

DISTANCE ALONG AXIS =

X OVERALL L£NGTH L:

02 0.3 . 0.4 Q5 0.6 0.7

L-::_ ~= - ii- .3" :.1 ·_-±:::-: ----1-- ---- - --C1'

'- ~ ........

-vAj ~ PIITCH jNGL£5

FIG. 34- MK 15-1 TORPEDO ( WITH RING TAIL)




! I I

I i

: -- -- -

I ' I

' ' '

I

I I

!

!

Q8 A. ID

£-,"' /:I'

~ ~7

i

p q

1.0

0.8

0.6

0 .4

0 .2

0

-0.2

-0.4

I

t

10

t

f. -

II '

" II

jt

I 0 . 1 0.2 tl !

1\

" ~ !, i\ r t\\ \\ I

\~~ '\'· ~-\,.L"

II

-

I I t-

0.3 00

I I

-35-

14 PRESSURE TAPS

QI~TAN~E AbQN!j AXI~ , OVERALL LENGTH

04 0.5 06 _l . I.

1""3"';,~ -

""CT_'_T" f i I

CONFIDENTIAL

16 18 19 20

X L

0.7 OB A 1.0

J l' ~ I ~ ~

I I "'"'!=

F IG. 35- MK 15-l TORPEDO (WITH RING TAIL)



Lee Side of Body

CONFIDENTIAL

COHF I DEHTI AL -36-

STATION 7

_:wrurrulri;nauftiHifrrwr:; I4r STATION 8

:R4E+HfH+HfH4fR-HA HffHl t±H4-1 STATION 9

~:H+HtH-1 1 HE·! H±1±H H flftitt f·l B~~ STATION 10

.:H:U;ttJ-1 ! 1·1 tfH 1:1 t 1:11±1 t-rtttfi l·t~H t ' STATION II

-_:J iff1'fH' I t l·ttN-H:I I NHt I tl t t1 1 ttl-H l :H:tfflfltt l ·~ft-H=BTI1tHtt l ffrifHzH

1eo• 1so• 140" 120" 100" eo• so• 40" 20" o• oo• 40" so• ec• 100" 120" 140" 1so" ISO "

CONFIDENTIAL

LEE SIDE VERTICAL WINDWARD SIDE c.

F IG . 36- MK 14-l TORPEDO

PRESSURE DISTRIBUTION AB OUT NORMAL CROSS SEC~IONS

AT STATIONS ON FOREBODY

CONFIDENTIAL -37-

STATION 2

081f!IJ" 160 • 140" 120" oo• eo• eo• 40" 20" o• 20" 40• so• eo• 100" 120" 140" 160" 1eo"

~- ~ 1-- - '-~-:::" Fr' - -~ "'"---: ·-

~- -~-- ~+- >- ;. .... ~ --0.6

r-~- r-+ ,.-- 1-t'' r- - l-... ... 1--1- -" r-0.4

0.2

0.4 STATION 3

~IG 1£. &:..-~ '"" / v .. ~.

'tW ·~ -~k ~-!;:- - .. t---. 0.2

--"' ~- A - -;:;;:: 0

........ -~ .. .. ·- - -r- -· -- .. -~ r-, - ·--02

-0.4

STATION 4 0

..£ l---

... _ ...._ -

q -0.2 ... ~:::: + t- ·-~ -. --:::. ~-t:::::. ~- ..... _:: ~

_, ~· r-~ r- ·- ..... - . - - _.., ......

"I- - ....... -OA

-0.6

0 STATION 5

.()2 --_ ... ,_ ..... ~ :.! -- + - 4- - -~ ::--

.::::. ~ · .... -::r"" '"'OOj

·- ...... -- - :;~ - · ,_ .. -- ,__ " ---04

- 0.6

-:H,HfH+ffHE-1-H1fl·ltff11TiiitB+H 1eo" 1eo" 140" 120" oo• so• 6Jf 40" zo• o• 2d' 40" eo• eo• of 120" l4<f 160" lBO"

LEE SIDE VERTICAL WINDWARD SIDE

'-FIG. 37- MK 14-l TORPEDO

PRESSURE DISTRIBUTION ABOUT NORMAL CROSS SECTIONS

AT STATIONS ON FOREBODY

CONFIDENTIAL

CONFIDENTIAL -38-

STATION 15

JHtfHliii~H±HfHtBi~l ftH-flfl-fHE STATION 16

_:,g!rttH 1-1 tl·ll-rtH=fHtH-FI ttlfffi fl-~t+t _:H:tffJ t t·lll·l f~ff±H=H-EIII·tftll iiHCH

STATION 18

STATION 19

_:~tH-H-llld-B+H lf.Htl±HJ 1·1 f 1·1 f+tl# · STATION 20

~.8·11Hftl f HfB I ttHdffi4+H+HMJH1 STATION 21

_ ) ~u·11 tlil·l t 1·11 l I I l·tttfflftf-IJE:H-ft-i STATION 22

:fJ~UHf.JlHMHfHl.l{ll:l t±l.l t±.tJ.U Ul

CONFIDENTIAL

LEE SIDE VERTICAL WINDWARD SIDE <S.

FIG. 38- MK 14-l TORPEDO (STANDARD)


AT STATIONS ON AFTERBODY

CONFIDENTIAL · -39-

STATION 15

~Bfffi:ffHB lTI4-Bf1+B~t f I 'f1 tl r fHi+r STATION 16

_:,HfH·I H·lti"H-fti-H-fN-Hi fi"H1tl t·ft~·~f •

STATION 17

_:,fffH+H-1 trl Htf1:H I:Bt ltttD-H4fH:I t -STATION 18

~ :,f H r l·llll f H I H f I+ I H H 1 t HlH I H H=H

~H+t I +I+H fffH H·RdMtHfH J~ M~11~ STATION 20

STATION 21

~B·I ttltJtHi t 1·11 1·1 tiJ+tr~zfttB-tt-H~H STATION 22

180" 'Sf 140 • 120" 1oo" a:J" so• 40" 20" o• 20" 40" f:IJ" eo• oo• 120" 140" 160" ltll"

LEE SlOE VERTICAL WINDWARO SIDE

c.

FIG. 39- MK 14-l TORPEDO (WITH RING TAIL) ·


AT STATIONS ON AFTERBODY

CONFIDENTIAL

CONFIDENTIAL -AO-

CAVITATION AND PRESSURE DISTR.IBUTION

Cavitation J or the formation of vapor-filled cavities J qccurs in hydraulic machinery or on underwater projectiles ~hen the pressure at any point on the body becomes equal to the vapor pressure of the water . A knowledge of the pressure distribution around a

:projectile should , therefore J give an indication of the suscepti bility of the projectile to cavitate . As defined in the preceding section , the data presented herein are given in terms of

(._..!:._) q

• In order to have cavitationJ the pressure on the bo d y J P J must equal the vapor pressure Pv, or

p = p = v . ( ..1:_ ) i/ 2 p v2 + P

0 q

From the above equation it is evident that cavitation cannot occur on the body at a point having a positive value of (p / q) , for then the static pressure P

0 must be lower than Pv, and the entire

volume of the liquid would boil . With a negative (p/q) _, it is seen that J for a given water temperature (i e ~ given PV) J cavi tation conditions are approached as P

0 is lowered or as V is in

creased , As cavitation is brought about J it will begin at that point on the body having the lowest value of (p/q) Thus J the lowest value of (p/q) measured on the body is an index of its susceptibility to cavitation , and is normally given as the cavitation parameterJ KJ which is defined by

K

Comparing this equation with the expression for (p/q) , it is seen that K = - (p/q)min • Le .; the cavitation parameter for the inception of cavitfrt1on on any shape is equal J but of opposite sign J to the lowest value of (p/q) measured on that body

The curves of Figures i2J 1.8 J 24, and YJJ indicateJ th e refore, thGt the inception of cavitation on these torpedoes should occur at a K value of about 0 . 36 . which is in good agreeme nt with the value of 0 . 34 reported in Referenc e i from direct observation of cavi tat i or:

•As the value of K is lowered further : th e zone of cavitation grows and the pressure distri.IDution is modified because the WL,er now flows around t h e vapor pocket as well as around the body Nevertheless., from Figures i2 s 18 24 _, a nd 30 it could be predict ed that as K is lowered a point would be reached where the pressure on the body at the second minimum pressure point (on the afterbody) would become equal to the vapor pressure of th e water:, and a second zone of cavitation would develop there

CONfiDENTIAL

-41-

FIG. 40- CAVITATION ON MODEL OF M~ 14-1

K = 0.25

FIG. 41- CAVITATION ON MODEL OF MK 14-1

K = 0.15

CONFIDENTIAL

The photograph of Figure 40 was used in Reference i to illustrate an early stage of cavitationJ some time after inceptionJ at a K value of 0. 25. It is seen that the cpvitation occurs approximately in the zone where the value of p/q is lower than 0. 25. As the bubbles are carried downstream into a region or higher pressureJ they collapse and disappear. Figure 41 shows a more advanced stage of cavitationJ at a K value of 0. 15J with a second well developed zone of cav1tation originating o n the afterbody.

CONFIDEhTIAL

CONFIDENTIAL

PRESSURE INTAKE S FOR DEPTH CONTROL AND DEPTH AND ROLL RECORDER

DEPTH CONTROL

To enable a multi - speed torpedo to travel at set depth under all conditions of speed and orientat1on with the direction of travel, itis necessary that the pressure impressed upon the hydro static diaphragm of the depth~ control mechan ism be at all t1mes equal to the static pressure of the water at the actuul running depth of the torpedo This is best accomplished by locating the pressure intake to the hydrostat at a point on the body where the pressure at the surface, unde r all conditions of speed, yaw and pitch, is equal to the static pressure in undisturbed water , that is, at a point where p/q is equal to zero at all yaw or pitch angles . Also , the intake opening should be flush with the surface, at right angles to it , and with smooth edges ,

Examination of Figures i2 and i8 shows that . on the Mk i4 " i afterbody, p/q = 0 where X/L = 0 855 , or at a distance of about 35 inches from the tail end, slightly aft of piezometer Tap No ·2i (see also Figure ii) " The same location also holds for the Mk i5- L On th e MK i5- i curves., because of the greater length of th i s torpedo , this is at X/L = 0 875 Inspection of the transverse pressure distribution about Station 2i (Figures 38 and 39) . shows that with zero yaw the value of u/q at this station is just barely lower than zero , and that it var es but slightly with yaw, rising on the lee side and dropping on the windward side . The best arrangement for the pressure intake would be , therefore _, through a piezometer ring connecting four small openings uniformly distri b•.lted about the circumference of the torpedo and 35 inches ahead of the end of tile taiL With this arrangement .• the sl i ght yaw effect would be averaged out.

With the pressure intake at any other location on the after body, it is evident from the p-ressure distribution curves that the pressure at the surface would, for a given yaw angle . differ from true static pressure by a fixed fraction of the velocity head For a single-speed torpedo the pressure impressed on the di1phra~m would differ from static pressure by a constant number of feet _ and this can be taken into account in the calibration of the depth setting 1o1echanism In a multi -- speed toroedo J this method of cor~ rection would require a different calibration at each speed .. · ·An ·

other method of correcting for mislocation of the pressure intake is to so design the intake that the pressure transmitted to the ~iaphragm differs from the normal pressure at the surface by the required fraction of th e veloc ity head Th1s can be done by dr1l · ling the pressure· taps at some angle other than normal to the sur face , or by using scoops or baffles These methods , howeve r_ are likely to be highly sensi tive to changes i n yaw o~ p i tch It is evident , th erefore .• that if the present arrangement of the pressure intake is unsatisfactory , the best solution would be the one recommended above , that is with smooth - edqed piezometer open ings drilled at right angles to the surface and located where

CONFIDENTIAL

-43-

p/q = 0 The experience of this laboratory indicates that piezom eter openings with slightly rounded edges (to a radius of about i/6 the bore diameter) are more accurate and reliable than sharp edged openings

INFLUENCE OF PROPELLERS

It should be noted that the tests reported herein were made on a model without propellers The operation of the propellers on the prototype torpedoes may modify the pressure distribution on the afterbody , so that the best location for the pressure intake may be slightly ahead or aft of the position indicated above

DEPTH AND ROLL RECORDER

The require~ents discussed in the preceding paragraphs in connection with the location and design of the pressure Intake for the depth control mechanism apply also to the pressure intake for the hydrostatic diaphrag~ of the depth and roll recorder if the instrument is to record true running depth Since this Instrument is installed in the head; it would not be practicable to connect it to the point on the afterbody where p/q = 0 . Connection to the point on the nose where p/q = 0 is not recommended because at this point the pressure varies greatly with yaw or pitch If the depth and roll recorder does not record true depth. it would probably be best to determine the magnitude of the error and apply a correc tion

It should be borne in mind that the depth control mechanism and the depth and roll recorder should not be used as primary in struments to check each other ., because it is possible to have the torpedo run above or below set depth and at .the same time to get a depth record which indicates a run at set depth The pressure distribution curves show that the pressure over most of the su~

face of the torpedo i:; lower than static pressure It IS possible _. therefore ; that the pressures impressed on both depth control and depth and roll recorder diaphragms are lower than static pres · sure In this case. the torpedo would run below set depth but the dep·t.h and roll :recorder would indicate a depth shallower than the actual running depth _ and ·thus the error may not be detected

office of scientific research and development · 2015. 6. 30. · office of scientific research and...

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