Th Oh Re VP NOSC- IK-S/Y Tone sO WS ee 4%. es < in © = ; . chic \NP = Lr Sle anQOier ae ~roA\\Vvs as SNe De or e Dp 0 15 ON ar — i distributed by fq Defense Technical Information Center NTA DEFENSE LOGISTICS AGENCY Cameron Static - Alexandria, Virginia 22314 UNCLASSIFIED oow30 NOTICE We are pleased to supply this document in response to your request. The acquisition of technical reports, notes, memorandums, etc., is an active, ongoing program at the Defense Technical Information Center (DTIC) that depends, in part, on the efforts and interests of users and contributors. Therefore, if you know of the existence of any significant reports, etc., that are not in the DTIC collection, we would appreciate receiving copies or information related to their sources and availability. The appropriate regulations are Department of Defense Instruction 5100.38, Defense Technical Information Center for Scientific and Technical Information (DTIC); Department of Defense Instruction 5129.43, Assign- ment of Functions for the Defense Scientific and Technical Information Program; Department of Defense Directive 5200.20, Distribution State- ments on Technical Documents; Military Standard (MIL-STD) 847-A, Format Requirements for Scientific and Technical Reports Prepared by or for the Department of Defense; Department of Defense Regulation 5200.1-R, Information Security Program Regulation. Our Acquisition Section, DTIC-DDA-1, will assist in resolving any questions you may have. Telephone numbers of that office are: (202) 274-6847, 274-6874 or Autovon 284-6847, 284-6874. aeons Dt Ze 2 ize UTION TEST CHART OF STANDARDS-1963-A° MICROCOPY RESOL PATIONAL BUREAU Pei AU Wy i J ! 4 i ‘ Aw , { i i i | i a \ \ 1 i nolan iV pag = j 4 f ee a ‘ APRA i i ar a i f i | abo vir (1) i i ; th ae 1 } A i { hath raked { nn } i ait eS Ry { ! i r it f wy 1 i | m5 ; ; 5 { i , bat i j ; ; i in H f i if 1 Ti a ist } yin BB et UME SH INTE Cepeaes NOSC TR 579 & ao = Bs ise) (=) Fe 5 hf if i fate ce A = gS 2 8 = ad an *e3 c & bs t2 < =} o. © G2 en = 7 a Q, q@ ES) (2) ‘ GS) = os) a aS } 2 SS 2 = o 6 : 3 B= a ug oS a Ss @ S fm oe = 2 2 3 aN ou eb) as le © r=) 2 = = re x a= 5 =2 . a. uy SE Goda os = © es 6g = en Ue © B > 73 o£ = OG ee Be 2 ; ae aR && et = = i = @ 6 OS } os ow “ wae 30 = ©} << G e@5 >a rm) a es @ 3 VI bi) G@ 3 3 ons & & = £ & ti! es) tll bedase EDR 62S UL ISON Csr 260 7 av rn Tad Se ainteng KAM Serpe hae nig aiid. a a Ca t H ap Doe OCEAN SYSTEMS CENTER, aaa PIECES CA 92152 AN ACTIVITY Oy a 1S NAVAL MATERIAL COMMAND HL BLOGD Technica! Director si GUILLE, CAPT, USN Commander ADMINISTRATIVE INFORMATION Work was performed with IED funds under Program Element 62766N, Project F61512, Task Area ZF-61-512-00) (NOSC 530 ZD51), and for the Transduction Sciences Block Program under Program Element 62711N, Task ZF-1 1-121-001 (NOSC SU1 2), by members of the Marine Sciences and Technology Directorate (Codes 53 and 52). This report covers work from 1 May 1979 to 30 April 1980 and was approved for publication 21 July 1980. The support of NOSC I[R/IED management is gratefully acknowledged. JM Walton restarted the thinking toward a flat linkage approach and did an outstanding job on the engineering design. GO Pickens originally suggested the flat linkage approach, contributed valuable counsel, and managed the Transdec tests. TE Stixrud gave valuable advice, assisted at the Transdec tests, and managed the Lake Pend Oreille tests. LE McKinley gave valuable advice, as did VC Anderson and FR Abbott. Interest in and support for the Lake Pend Oreille tests by DL Carson and JB Fransdal is gratefully acknowledged. Drafting and machine work were performed well by CV Cargill, Jr and R Roa, respectively. Released under authority of JD Hightower, Head Environmental Sciences Department METRIC CONVERSION eatin Rap ananassae EHD GE YS 2 To convert from ~ feet pounds pounds of force per square inch (psi) dynes/cm2 ergs horsepower To metres (m) kilograms (kg) pascals (Pa) Pa joules (J) watts (W) armen nt EET BEY ETEN PAPE IT AD Multiply by ~ 3.05 E-01 ~ 4.54 E-01 ~ 6.89 E+03 1.00 E-Q] 1.00 E-07 ~ 746 E+02 SICAL Se SAUNT es RE aaa A Wot i a y WA dies mite mi nit } : Ht ae nee rah Sah es UNCLASSIFIED { {Lf ) f Fy Se f 1 -4 47 SECUAITY CLASSIFICATION OF THIS PAGE (When Date Entered) wah | Ve #i / JS, fis 4 sees ul fit sat / REPORT DOCUMENTATION PAGE eee ae READ INSTRUCTIONS : [). REPORT NUMBER ~~ 12. GOVT ACCESSION re 3. RECIPIENT'S CATALOG NUMBER NOSC Technical Report 579 (TR 579)" AID ~ A O92 =) i$ cL ; so Ra eI ea Sokal PE GF eee & PERIOGO COVERED eG | NONRESONANT ACOUSTIC PROJECTOR, PROJECT. ame } Final FeCq Lb ——— 7| + Mechanical 5- 59 Hz device > provides s stable underwater gcoustic output | 1 May §979.%0 36 Aprita £980) | | with frequency and amplitude conbellabie and pind penen of depth. 6. iPERFORMING ORG, REPORT NUMBER 6. CONTRACT OAR GRANT NUMBER(a) | (ae ; OT It " HA|Wilcox | [uy ! GA; Gul Ss j ; a sues tm ; pe a aaee eae L 3 PROGRAM ELEME SN EC OrE eT TASK AREA & WORK UNIT NUMBER 62766N, F61512, od §12 001 (NOSC 530 ZD51); 62711N. ZE-11-12 1-0 NI cI eee co 5 DD Junssio8o/ j , 9. PERFORMING ORGANIZATION NAME- ANNO ADDR ES Naval Ocean Systems Center San Diego, CA 92152 255 eae Poe 1 ep opie PS LE) JCMS Ae Lp 12 Sunesto8 SHMUMBER OF PAGES iadsie 2) a) 50 if 14. MONE ORING AGENGY-HAME © ADORESS(if different {rom Controlfing Office) 1S. SECURITY CLASS. (of thfa report) Unclassified BDECL ASSIFICATION/ DOWNGRADING SCHEDULE 16. DISTRIBUTION STATEMENT (of thle Report) Approved for public release; distribution unlimited 17. DISTRIBUTION STATEMENT (of the sbeiract entered In Block 20, If differsat from Regert} 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse aide if nececoary end tdantify by block number) f Underwater sound generators Mechanical components | «= Sources Linkages Standards: Nonresonant Acoustic Projector 20. ABSTRACT (Continue on severae alde tf necessary and identify by Slock number) {> The nonresonant acoustic projector was designed, fabricated, and tested without significant difficulties, It met all its specifications, and it proved the principle of a mechanical projector whose operating depth, frequency, and amplitude of piston throw can be simultaneously or independently vmied without incurring significant inter- actions among the variables. The validity of considering the nonresonant acoustic projector as a standard source was demonstrated. y. \ DD (FORM 1473 Evitiow OF 1 NOV 6S Is OBSOLETE S/N 0102-LF-014-6601 UNCLASSIFIED SECURITY CIASSIFICATION OF THIS PAGE (Whon ee Se tye hs se iy my maa eet ng Ns " i ny a # ay Oy, a 4 Naa Sey, ite: : clan Heng r i i (UNCLASSIFIED SECURITY CLASNFIGATION OF THIS PAGE (When Deta Entorad) (UNCLASSIFIED) a ee SECURITY CLASSIFICATION OF THIS PAGE(When Date Entered) § i —-. Sosa a PSN EST SUE SETI ITE CRETE a Rant tn aaaeial mam. Laue Ath lie OBJECTIVE Since there are no inexpensive acoustic sources in the 5 to 50 Hz spectral region for generating controlled underwater sounds, investigate a newly designed nonresonant source of the mechanical type. Build and demonstrate operation of the new type projector at a source level of about 172 dB re | Pa at | m. ; RESULTS 1. The nonresonant acoustic projector was designed, fabricated, and tested without significant difficulties. 2. It met all its specifications, and it proved the principle of a mechanical projector whose operating depth, frequency, and amplitude of piston throw can be simultaneously or independently varied without incurring significant interactions among the variables: 3. The validity of considering the nonresonant acoustic projector as a standard source was demonstrated. RECOMMENDATIONS 1. Apply the nonresonant acoustic projector type of acoustic source to such Navy problems as: (a) probing and characterizing the océan’s various acoustic paths, (b) measur- ing effective horizontal sound speed over ocean paths of Navy interest, and (c) calibrating and measuring the sensitivity of the Navy’s ocean surveillance arrays. « 2. Promptly develop the “switchable nonresonant acoustic projector” concept for application to significant Navy problems. Aecession For NTIS GRA&I WEG Als: {a | Urannovneed Gi Tastirication Availability RST RTS t Sect} Nie ae ie ein oii ‘Wie yin ; cit ae oi LANE dena cae hii ai viel a sf mi PPh, EVOLUTION OF THE DESIGN CONCEPT The Nonresonant Acoustic Projector (NRAP) Project got its start with this author’s suggestion for a system called Friendly Acoustic Sources. On finding that there were no suit- able, inexpensive sources in the 5 to 50 Hz spectral region available for the Friendly Acoustic Sources concept, he was Jed to investigate first resonant then nonresonant sources of the me- chanical type. Resonant sources were abandoned because they operate on the principle of the resonating gas bubble wherein the resonant frequency of oscillation is given by the follow- ing relationship: * 1 kYP’ Hes (Riess Re ; (1) 27 RON Gp where f = resonant frequency in Hz R = linear dimension of bubble in cm k = number of order ] dependent on the configuration of the bubble (for example, k = 3 for a spherical bubble with R denoting the radius) y = ratio of specific heats of the gas at constant pressure and volume y . : fe) P = ambient ocean pressure in dynes/cm= p = density of gas in g/cm3. Equation (1) shows that a resonant source’s linear dimension, R, must be large — thus the source must be relatively expensive — when the design frequency is low and the depth of operation is great. Also, small excursions of the source in depth change the pressure, P’, as well as the source operating frequency. f. (Or if fis forced to remain constant, changes in P’ generally cause the source to operate off resonance, with corresponding large changes in the source’s radiated power level.) All these problems can be avoided by going to a nonresonant type of source. Therefore, the nonresonant acoustic projector design concept shown in figure | was for- mulated, and the NRAP project was sponsored by NOSC management.** During the initial phase of the design effort the author concluded that the approach shown in figure 1 would entail overly large aerodynamic windage losses. A suggestion by FR Abbott concerning the MK VI minesweeper source then led to a cam-type design (fig 2). Further work showed, however, that this system would require an unduly expensive cam plus large, expensive cam followers. GO Pickens and JM Walton had independently suggested that a flat linkage system driven by an eccentric might do the job. However, all such systems apparently needed a sliding element, which would be energetically lossy as well “as somewhat unreliable in operation. LE McKinley then suggested that the Walschaert valve gear (for old-time steam locomotives) be looked into, and this quest resurrected the Baker modification of the Walschaert system. Finally, a modification of the Baker system in turn vecame the basis for the design that was used successfully in the project. *See, for example, NAVMAT P-9675, Physics of Sound in the Sea, p 462. **Other low-frequency nonresonant sources exist, but none combines all the advantages of this one so far as the author is aware. aE ACES Re MEN Vitor ee ay | ‘ : viiteeee RNR ean " i mn hua test i itil ah Ae he an vali i he fs hk ain iy ak ca aa cr DN Naame HA dupteley ig gh abd te idea atte hh t Yuba Middl i i < ines uA i tl 7 : ! pp iste eden teeta i wae Te , eee iN ; on hati hin ‘utr is iV hv Tisai 8 x itis ts pal pa i Yoke pe! th ; ies te one Min bitin banal Meith, PLANE OF MIRROR SYMMETRY PROJECTOR HOUSING He As) MV RIAD. OSCILLATING THRUST BEARINGS BEARING MOTOR BALANCE SUPPORT GEAR BOX WEIGHT Wee SUPPORT OCEAN N a; PROJECTOR HOUSING NOTE: FLYWHEELS COUNTERROTATING TO AVOID GYROSCOPIC EFFECTS Figure I. First conceptual design for NRAP. ’ TS NNR PT AS EEA NOSIS ER ESL EPSTEIN TN a ~~ it Cc a pliyanalubeae thet Se 4 Led f 24 ROTATING / cc oO THRUST Sa HEIGHT ik Ue. DIAPHRAGM o AIR PROJECTOR’'S AXIS OF CYLINDRICAL SYMMETRY | ROTATING } MACHINERY AXIS ADJUST SCREW i weg ih ia Ba en n Reon) by ae , ‘ } i ms UL, at ; ; Mh eae eclve Jarl inhi ; a he mime ri y se sav eu ae ielies a . i SE oie al Ae he be NA Ni 8 i Wa tiki ( a WetN Re, pit i iw iy, i ‘ u { Lid aloe Sak Pn OTE i i ) aha gc aah We } ; ‘ Tat i l f ay a Po AS bhigvhe va LVS sorte inne AS eat : a ‘ORR Pr liana WS Nay A | i | uahaeaik a Mi sa il Nak Giochi DRY Ek Osea eal a ; 7PM AAA omen ley apace haa ani Wet ease i Ths ts in } i 2 il Lee i 1 1 y : ' A i ‘ ‘ mR J i \y Hy HE EY j | a fail ESR Viel : i vw eens } ? We i - vA Le “AVA i j “iis SO AIR PRESSURE TO COMPENSATE | LA aa FOR EXTERNAL PRESSURE , ye ie ag: Lie — CARI Na va ici ee y as il PISTON — | FACE t i a : a V/CLINEAR. ~ BEARING - OCEAR SQUARE eae SHAFT f SQUARE Po ee } SHAFT | | Ao “Tita i ot RATIO TTOS TOTES se “SPISTON VI 7 SEAL 7 POSITIGNING | _ SACK (NON- J ROTATING) 2 YZ 3 * ee _ POSITIONING a MOTOR Figure 2. Second conceptual design for NRAP. DESCRIPTION In the NRAP (fig 3), a low-power, efficient, de series-wound electric motor drives one or more pistons by means of an adjustable linkage system. The pistons all operate to- gether to change the projector’s volume in the breathing mode of oscillation. Up to six or eight pistons can be accommodated on a single rocking cross arm, and several such arms can be ganged on a single shaft. The unit described here, however, employs only two opposed pistons. Since the operating frequency of the rotor and pistons varies with the voltage ap- plied to the motor, the source can be made to generate either a constant frequency or a frequency-modulated signal as desired. Applying voltage to the screw adjustment motor moves the amplitude adjustment link to control piston oscillation amplitude. If point F on the amplitude adjustment link is fixed at the location shown in figure 3, point C is forced to oscillate along arc G as the rotor turns. This makes point D oscillate along arc I, which is centered on the fixed point E. Since the rocking cross arm is forced to rock with near-sinusoidal angular motion about its fixed point E, the pistons are driven in and out at the rotor turning frequency. If the amplitude adjustment motor is actuated to drive point F into coincidence with point D, are G swings into coincidence with arc H, which is centered on point D, and both D and the rocking cross arm become stationary even though the rotor continues to turn. If the amplitude adjustment motor is actuated to drive point F to a location between point D and that shown for point F in figure 3, arc G swings OCEAN PROJECTOR at HOUSING PISTON (TYPICAL) _ LINEAR BEARING (TYPICAL) APAPLITUDE =a ROCKING ADJUSTMENT CROSS ARM TO PISTON (NOT SHOWN) ; ——> AMPLITUDE ADJUSTMENT LINK ROLLING SEAL (TYPICAL)- AIR INSIDE | HOUSING he »” OCEAN OUTSIDE HOUSING Figure 3. Third conceptual design for NRAP. nated . “: 4 ati | i maanne te | Me i, i , a Light apy 4 nine OF at hie? NE enti di iy: ei 7 he 1545 | ath Kiely il Me TT), inig i ine ‘hail galt ‘baal ih oe Phe £1 apc vib bat itv i Bt Nai i Pid Su 0 AA f Vian Rh inida avi aa | ; Alb wiih atu dalle! vi i Ge ya a miig ees Bia F i Hb ey bae ui Wiel i y PLE ar nha | Mea OAD Apia ay (i } i i 1 iw it - i, eo! uth i pa j vain eine % \ - * Moeey oo lla fies wee Vea i ; into a position somewhere between are H and are G shown in the figure, and the amplitude of motion of the rocking cross arm and pistons increases to something less than what it was in figure 3. Note that both the frequency and the amplitude of piston motion can be adjusted independently or conjointly while the source is in full operation. Changing one without changing the other generally causes the output power of the projector to change — see equa- tion (5). When the piston amplitude is set to zero, the rotor drive motor can be started for any depth of operation of the projector, since the motor then has to overcome only the friction of the internal bearings. Once the rotor is turning, the piston amplitude can be ad- justed as desired, without difficulty. When the amplitude adjustment link has been set to a definite location, the pistons are coupled tightly to the rotor. Therefore, the frequency of the piston motion is determined only by the rotor turning rate. Also, the link amplitudes of motion are determined only by the rotor-linkage geome2try. Asa resuJt, both frequency and amplitude of the piston motion are independent of the pressure of the air inside the housing and the pressure of the ocean outside the housing. Therefore, changes in the operating depth of the projector do not change either the frequency or amplitude of piston motion. Consequently. the system can be designed to operate in a pressure compensated housing. A nominal overpressure such as 5 psi can be maintained within the housing, thus eliminating the need for heavy (hence expensive) housing walls. If a leak develops in the housing, t! 2verpressure inside prevents intrusion of ocean water into the interior. The overpress!ue also prevents bearing play or “backlash,” which would produce distortion of the output wave form and energy loss in the piston drive train. Additionally, the overpres- sure prevents reversal of the rolling seals during operation. Since the amplitude of piston motion is determined by the location of the amplitude adjustment link and the frequency of motion is determined by the rotor speed, the NRA projector becomes in effect a “‘standard source” whose acoustic output power level is con- trolled only by the projector’s operating parameters together with the intrinsic parameters (density and sound velocity) of the ocean medium. Since small excursions in the operating depth of the source de not influence the latter quantities to any great degree, the NRAP does not require complex or precise calibration with exterior devices cuch as calibrated hydrophones located at well-measured distances from the source, etc. Moreover, the acoustic intensities radiated at the fundamental as well as the higher harmonic frequencies can be calculated directly from the values of the linkage parameters used in the projector. Important in the concept of the NRAP is the flywheel. This unit is rigidly connected to the rotor and hence tc the pistons. Therefore, the high reactive power tiow into the ocean during half of each piston cycle is recovered by way of an equal reactive power flow back into the flywheel during the next half of each cycle. As a result, this source has higher efficiency than many types of low-frequency projectors. Because large peak forces exist in the linkage system under most conditions of operation, the bearing frictions are correspondingly large and all linkage elements must be sized to withstand the peak forces. For the purposes of this “‘proof of principle” project .he NRAP was designed to provide an output sound pressure level of 171 dB re 1 uPa at 1 m — about | W of acoustic power — at a frequency of 15 Hz. The diameters of the pistons were chosen to be 11.25 hddlagty ills yin nad gest) nel dit ua vane win cyt ete woe hil) tid priest ail) mM ees) ; 2M Ae fai - 6 yy ra eet aber yi ab AN PL COLIN sa ReaD ipa ial eth My baie, if Ldueihb beni i quiet by, | A wh ayrget hou ws wihoned any md, i ia arp aa myht vibes # ne ‘over Signy 8 sa ‘e 64 i Aye yi inches, and the diameters of the mating apertures fe: the pistons were chosen to be 12 inches. The annular gap between each pisten and its mating aperture is sealed with a rolling rubber seal (fig 3). The front of the seal advances just half as far as its piston. Thus if the piston advances a distance s (in cm), the volume change produced in the projector (in cubic centimetres) is a) 4 D) (/4)D,-s + (n/4)(D,~ -D,~)(s/2). (2) whiere Do = piston diameter in cm D., = aperture diameter incm. The term on the left is the volume change prcduced by the piston’s advance. and the term on the right is the volume change produced by the advance of the seal. The volume change expressed by equation (2) can be equated to that produced by a tight-fitting piston of “effective” diameter De, hence the equation (x/4)Dg"s = (n/4)D 7s + (1/4) D,7 - Dy”) (5/2). (3) Solving this equation for D,, a 2 2 Ne A Dera (Dng Dr )/2 : (4) Inserting the values for Ds and D,, yields an effective diameter of 11.631 inches for this projector. The formula for the average acoustic power. P, from a source with small circular pistons operating at low frequency in the sinusoidal breathing mode is as follows:* P = 2n3(p/c)f4 (A-s)-, (5) where = average radiated acoustic power in ergs per second = water density in g/cm3 velocity of sound in the water in cm/s = operating frequency in Hz Dee AS as) I = total piston area in em- s = amplitude (half the peak-to-peak excursion) of each piston’s motion in cm. Inserting the values for the present two-piston NRAP operating in fresh water (corresponding to the case at the Transdec or Lake Pend Oreille facilities) yields s = 0.197 inch for P = 4 watt (= 10/ ergs/s), 9 = 1.00 gjem>, c= 147 950 cm/s, f = 15 Hz, and, for total piston area, A = 1371 cm2 (= 2(a/4) (11.631 X 2.54)2). *See, for example, Acoustics, by JL Hunter; Prentice Hall, 1957, p 147. oar nein ren pnmnt errrnertnatnmpe ts mri nA ey Rr Se Her np pane NSH sata it pC RAR tera EUR TIES DADS IIL ND NER IT TLE BG EELS DIT MCSF a Figure 4 shows the completed NP.AP in an oversize housing with walls chosen to be much thicker than necessary. The rotor drive motor is a dc motor rated at 1/12th hurse- power. !t drives the fly wheel, housed in a flat cylindrical enclosure, by means of a V-belt and pulleys. The projector has two opposed pistons. Figure 5 shows the underside of the horizontal plete seen at the middle of figure 4. One piston push rod with its piston face removed is seen passing through its linear bearing #t the left. In the center of figure 5 is the rotor partiall:’ bidden under the eccentric drive pin labeled B in figure 3. In the foreground of pin B is the pin labeled C in figure 3, and to the right of pin C is the pin labeled F in figure 3. Prominent at the right of figure 5 is the amp- litude adjustment motor and its associated screw drive assembly for moving pin F. Below and between the screw drive assembly and pin B can be seen part of the rocking cross arm. The linear transducer provides a precise electrical indication of the location of pin F and hence of the amplitude of piston motion. eS VAY REAR ONCE ARNOTT Car MR RRL NE NPT NEL A SAL PTE nae a gre bien ae i hac les de THe eat ah ie Rania: ave Hh jpeteaglgil ‘aie acnien, ai iti W, A Tat lata i Ne eT ah 4 vt som ty i . halla why . .. 7 FLYWHEEL a ROTOR i (IN DRIVE ENCLOSURE) PULLEY V-BELT MOTOR . Bee j i 2 ° HORIZONTAL PLATE 4 AMPLITUDE : 4 ADJUSTMENT j “1 MOTOR 4 Ei i = x ¢ % FSM ey eerie f 4 i LRO 1348-4-808 OPPOSED : PISTONS j Figure 4. Two-piston working model with one side of housing 7 removed to show interior mechanisms. 10 Dae tah Ny bist ROCKING SCREW CROSS DRIVE ARM ASSEMBLY PISTON ~ ECCENTRIC AMPLITUDE PUSH LINEAR ~ DRIVE PIN GEAR ADJUSTMENT ROD BEARING B (FIG 3) ROTOR BOX MOTOR PISTON FACE REMOVED = LINEAR . TRANSDUCER PINC (FIG 3) ae PINS (FIG HORIZONTAL PLATE LRO 13504-8608 Figure 5. Underside of horizontal plate, showing the linkages. 1] DB Se en eae CER f ’ SABIE PAN SIU SS eat sees Rs 4 Ed a ? 3 t 6 ¢ Sires z a R 3 : z PNAC PIN a SNS EAN é f ; i Fi q sek iio Shaan seb pated pd de oe nee at, ’ Ben SAW av re ie ee ‘ Oy tits aa Fee ed RU Ae Veatal hy Pave (he i a Ay 1 *, : ee, Hey ‘y Wit bd ps) a ae Y ry 4 f WE ; a vie 4 r if Beis Pet nt Uy ve ‘ , 5 ‘Ae Neo a i ai i 7 } Mil i i ieee i) ; We ' iY mah te ig if te t te ah f a) t f Th i i fy a te TOL ko ia re if Ne eed aye Tenet ie Vat) ueninad ya abtiw i A ai, q i aay i i F oe et 1 + i H a J mi by i} i K i iy Lay i bi way } i eis ‘y Wey j o , pana) HO r if i i ; TEST RESULTS BENCH TESTS Figure 6 is a calibration curve that relates the electrical indicator resistance to peak-to-peak piston throw (twice the amplitude of piston motion). Shakedown tests proceeded without problems. The V-belt (fig 4) was judged less efficient than had been expected and was replaced by a Berg “‘“Min-E” chain with matching sprockets. TRANSDEC TESTS The Transdec tests went without difficulties. Figure 7 gives the measured output spectrum with the basic NRAP frequency set at 15 Hz, and with the amplitude set at three - values of peak-to-peak piston throw: 0.391 inch, 0.124 inch, and 0.039 inch. The air over- pressure in the NRAP was maintained at about 2 psi. The calculated sound pressure levels at 1 m for these values (based on a water density of 1.00 g/cm and a sound velocity of 147 950 cm/s, as reported by LJ Orysiek, manager of the Transdec Facility) are 170.64, 160.66, and 150.61 dB re | wPa, while the corresponding values given by the Transdec instrumentation are 173.3, 162.7, and 152.4 dB re 1 wPa at 1 m. The discrepancies are all less than 2.66 dB, which is consistent with the +2 dB stated accuracy (from Orysiek) of the Transdec instrumentation, for a measurement taken under the conditions of the test. 0.3 Wi NOTE: MAX EXCURSION (e) 1S 0.391 INCH P-P ne AND 1S OFF SCALE FOR INDICATOR 0.2 na PROJECTOR THROW VS . REMOTE INDICATOR READING GOP/TES 4-3-80 PISTON EXCURSION, inches peak-to-peak ole. ae | SASS asta (a (¢) 1 2 3 4 5 6 7 8 INDICATOR RESISTANCE, kQQ. Figure 6. Piston throw vs linear transducer resistance. Tee Saif eat ty oh oa a andRiady, i 4 ¥ ; ah ‘ i bite ; Piva niearsy, i Ff Ue RD Kg ih i Ruy eax " Ae Hid wee + ¥ To Rep, fi ih) Ny mae rat i ie an , ' at i He i lene ' | vi i HK 4 Pita [ian 1/i})} f i a Ny ; i nel an \ h i } i } ‘t t ih ‘ a a 5 \ j ha hee PW , ny) ' i 1 C iw Bs th l RI ih i\ , Mp ear eran oot “YoUT 6£0'0—2NIq !Your 9710 49eI1g ‘YOUT 16¢°0-Ppaz Moly} UO}sId yead-o}-yeag ‘ainssaidsaao sie isd [ pue ZY | Ww 7 Unt yso} dapsuesy *Z sunBty 08 OL 03 F Va : ! i | a eee AON3NO3YHd 8xOLOY 7H 'AON3SND3e4 os Ov o€ 0% V QL perenne Dee Pee ee a cea une s tenes | ; | | } poo 7 asennad eee { | i ! | | d (WON) SP ZS1 + as ee noods | steeermm gee geUuc edie : yeas all has a tess | | | | L | | | E | t (WON) BPZit> } | lsc unos a w te eg | a4 gp TZA37 3 13 Mars ARG Ayia vem Figure 8 gives results similar to those of figure 7 except that the air overpressure in the NRAP was maintained at about 5 psi (versus about 2 psi in the first test). No significant changes in performance Were detectable from this change of internal pressure. Figure 9 shows the spectral output when the NRAP was set for (a nominal) zero amplitude of piston motion The fundamental was down about 45 dB relative to that shown in figure 7. More accurate zeroing can readily be achieved by closed-loop methods, if desired. Figure 10 shows the output spectra when the NRAP is operated at frequencies of 12, 1S,and 16 Hz. The maximum amplitudes vary precisely with the fourth power of frequency, as predicted by equation (5). LAKE PEND OREILLE TESTS DL Carson, Code 712, expressed interest in and provided funding for testing the NRAP ata depth of 500 feet at Lake Pend Oreille, Idaho. Therefore, TE Stixrud trucked the NRAP to that facility and conducted a series of tests there. The tests all went without difficulty. Stixrud’s 1-port of the tests is attached as appendix A, and details of the sound pressure level calculations are included as appendix B. PROJECTOR EFFICIENCIES While no great attempt has been made te measure or improve the NRAP efficiency, general observation of the voltage and current levels required to operate the rotor drive motor under various conditions shows that its efficiency is about | to 1.5 percent. EVALUATION AS A STANDARD SOURCE On 11 September 1980 the NRAP projector was calibrated at the Navy’s Acoustic Calibration Facility (headquartered at NRL/USRD, Orlando, Florida) to evaluate the NRAP as a standard source. The calculated NRAP source level was 170.61 dB re 1 wPa at 1 m under the test conditions pertaining, while the measured output level was 169.9 + 1.0 dB: hence the NRAP capability as a standard source was validated. THE FUTURE Since the NRAP design was originally conceived, modifications to the linkage system (appendix C) have made it possible to contro! the device as follows at suitable points in each cycle when the linkage system velocities momentarily come to zero: Turn the NRAP from zero to full-on and back again Reverse the phase of the output signal Switch the frequency from the fundamental to twice the fundamental and back again. The switching operations can be accomplished at the zero-velocity points without changing the flywheel velocity or jarring the other parts of the NRAP machinery. These features will make the NRAP suitable for such Navy missions as measuring sound speeds in the ocean, communicating acoustically between distant locations, and obtaining Doppler and other important information about the acoustic channels in the ocean. The cost of an NRAP unit, in production lots of 100 units, was estimated independently by JM Walton, GO Pickens, TE Stixrud, and the author. The cost estimates lay in the range from $5,000 to $10,QU0. i Sheen ianp cata 15 eas oa y 5 aes wane lie scl Sat Sadi Tot TEER MONRO Gie 4 ahh iN Gat sya! APE RAINE ae Hane FEMUAVEDN YE Yi Hh Hn Los jneep et he Cae) Nh Wie Dt aR | Cite thes yc “YOUT 6EO'O—2NI “YOU $7 1'O— HOPG “UOUT [EE"O-Par :mosy uojsid »vad-o}-yeag “ainssaidioao are isd ¢ pue ZY S] 3e ¢ UNL 1s9} OapsuBl] ‘9 aINBIy AONaNDaYS | yOLOY 2H 'AONSNDBYS 09 0g oz V | FRECEDING PAGE BLANKwNOT FILMED TE al eae a omesew retaner sme ese -aotecomeeee | | | | STAT PTO) PTC eT Vey [eee es || Pa ecs| Pe sWole | ! bie a eanet) | | ' i aan eae Ny ie: | wt wee c cece eee n eee n este es nant sare re seace pasds we. 1e eg | 21 gp ‘V4AA37 JOHNOS Ss qneaesdcnd pubes cogosesea0 J042(!19S ‘i Zi ere ci Aguanues) , i | SIEM TaN WAOUM UE | ees fad i iY ft Papa (WON) BP Z9L > i 1 SS Se ee! | : ee eeee te are PoC a Sener ee Sea ote SIE a a lb ey ee = ees Rue (C | Ses ES pis SE as) Ala F | | : Pe | (WON) SP ZLZL > | | J Sg Se ed | 1 * 2 i ? samnssoidsoao aye sd Z pus (O1Y) O10z 1NG) ZH S{ 1B p UN 3Sa} OopsuBIy 2H ‘AONSND3AY4 "6 ounaiy AONANDAYd YOLOY “F3A37 39uNOS us (8 egrl | er gp 19 PRECEDING PAGE BLANK=NOT FLLKED Peer h PARAS RET MERA ANDERSEN A MER SE Um Torment ae rooms treet je isa ace = sere egiem—en pore. § ie ; winrar flit 4 Las C a ‘ ay “2H O1—8nlq 2H C1—pss STH TINEA ‘aanssosdsoao sre isd ¢ pu Zpy O] pus ‘sy ‘T] Ie O] Uns isay SopsuBIE “OT aundIy i PsaGE BLANKeNOT FILO | PRECEDING 21 sol oaud YOLOY HSL Dau ¥OLO 7H ‘ADNSNDZUS 7 zg og Ov Ol | = StS rs eee ) | pee = re amen 5 yr Dai ee = fH iH gz i = Re ey a | : [es Soe See —-t-7 GEL \ | é, Sas \ | ty ! | n { [| ees Seer | nse 2 eons Wee ares fo ! Peels | | | | { ! ' avis} - me if | } | | | | { \ | t 1! | J | ee | sess see Sees eS | (ase al eee eS a=) { t pet jl : eee ao eae ise sare ee | ! \ ie ee re Wests steps aioe | H H Hi 0 { po | | i | i 1 2 Pst Co ae uMowiUn | | | \ oe Sry eae ee) Wicis = SPS Ua) Aeon ig al - puepuers | 310q > Bsus Ped 8c is ; tf poiiewe Seer Se elie = ee eee { | | i { | i | i } a Ne a a Lope ne Sat Ww | a2 eg | 2s §P “T3937 ADUNOS ti t t i i ii I a (its x m rei Sid H fy A Y y : fi TE it pay nisin | i i a bce Mane 5 Owe ihe a Leripwit F i hy } FT j } i eit i i ‘ i tae f { : ' Da ie } fon 4 ri i Wad hind pr , ; ' 4 ieee in’ ; Hy iM i, a : \ ou 3 K Pa OY , se ; ; % i S be. i a ean | [A Ae ighshone ee eee et Oey h } i eaters ‘Bou prog fos Opt a Nc 4 ne i { i uh i it j ie , a fh ? ; ; Le an Laren SP int Se hie ih ‘ . f rite Al cli A yl Nepean: teenie rurshiy 7 ciiee BE ieebinnie aie ulued * patty ¥ f : 2 . k: led a ; Sl get is Lo aa se hal AAR easiness RR CONCLUSIONS !. The nonresonant acoustic projector was designed, fabricated, and tested without significant difficulties. 2. It met all its specifications. and it proved the principle of a mechanical projector whose operating depth, frequency, and amplitude of piston throw can be simul- taneously or independently varied without incurring significant interactions among the variables. 3. The validity of considering the NRAP as a standard source was demonstrated. RECOMMENDATIONS 1. Apply the nonresonant acoustic projector type of acoustic source to such Navy problems us (a) probing and characterizing the ocean’s various acoustic paths, (b) measuring effective horizontal sound speed over ocean paths of Navy interest, and (c} calibrating and measuring the sensitivity of the Navy’s ocean surveillance arrays. 2. Promptly develop the “switchable nonresonant acoustic projector” concept for application to significant Navy problems. 43 : ERECEDING PAGE BLANK=NOT FILAED a fay ihe { in ete | er i Tr) re hentire ean te ore Ccoest Came CE ee Mana APPENDIX A: HAW-15* ACOUSTIC PROJECTOR TESTS AT LAKE PEND GREILLE, IDAHO 20-22 May 1980 by TE Stixrud SUMMARY The newly-developed HAW-15 sound projecter was operated at Lake Pend Oreille Facility for 17 hours at a depth of 500 ft and at intermediate depths for shorter periods of time. The unit exhibited no degradation of performance during this evaluation. It required an increase of input power as depth and internal pressure increased in order to offset the increased “‘windage™ loss of the moving parts. Most data were recorded at full power output. The source level of 171 dB re 1] wPa at 1 m at 15 Hz was computed by the volumetric displacement of the pistons and the characteristics of the medium. INTRODUCTION The HAW-15 has recently been developed by HA Wilcox, of NOSC, with IED funds. Its two opposed pistons are driven through a unique variable throw mechanism by means of asmall electric motor. The motor drives an intermediate flywheel. The flywheel stores energy from the pistons during one part of the cycle and returns it to the pistons during the other part. When the variable piston throw is set at zero, friction is the only system load and the motor-driven flywheel can be started at any operating depth. The acoustic source level can then be set as desired within the design limits. Frequency is controlled by means of the motor speed, 15 Hz being the nominal design value. The projector satisfied all expectations during the initial verifications at Transdec. This prompted DL Carson of this Center to provide funding for extending the evaluation to the much greater depth of 500 ft and a longer operating time at the Lake Pend Oreille Facility. PREPARATION A 550-ft cable was borrowed from Code 5314. Figure Al shows how this cable was connected. The transducer was modified as follows: 1. The cover plate was provided with guide pins and handles. 2. A S-psi differential pressure transducer was installed. 3. The V-belt end pulley drive system was replaced by a more efficient Berg gear and chain drive. Grease seals were installed on the bearings and all bearings were lubricated. = 5. Adapters were installed for attaching an air tube for No pressure compensation and fcr attaching an oil tube from an external oil bladder to the internally mounted pressure transducer. 6. Two adapters to couple nitrogen flasks to the scuba regulator were made. *In this appendix the subject nonzesonant acoustic projector is referred to as Model HAW-15. Bae eisent PRECEDING PAGE BLANKeNOT FILMED a a ES 2S FRSA em unueeRERYEAEE TRISTE ORNS AOTC TE IAN LoTR eV An igi he éi Wil Rai ; : ; fh) itt Dati ta oo Ds igea pie an ii i, PE de ahs We Leys 36 VOLTS—LEAD-ACID BATTERIES DRIVE POWER DRIVE 12V 12V 12V -————9 CURRENT = (TO VM) Veipal lea? +28) 130 ¥ 100 pF < 36V 19 er Oke - DECREASE AMPLITUDE + INCREASE AMPLITUDE | AMPLITUDE -0 TO 7.5 kQ =0TO MAX DIFF PRESS PISTON 1 POUND =1V ESN | Two | nee ei PARALLEL j PARALLEL 4 SHIELDS | SHIELDS Vas) | 4 #22 WIRES a _—— 7 QEACH t 2PARALLELI“*4 § i WIRES | i = 22 : | 3.52 CI A Sg ay 7 ee) : 9 NC pi O75 e RMG-2FS RMG-4FS ‘ AND BCL } | AND BCL ; 4 DISPLACEMENT OO aN TRANSDUCER s DIFF PRESS TRANSDUCER POSITION MOTOR Figure Al. Electrical connections. { meh Hise Aes RA 4608 CON RA HARD OH ike ons crt : a ries Ciienae aLowinl | re hin LL PY er a ae RORY ae ae 1 i i t 3 Ly ” Y yy ‘i I i ty Li bi on Le eae ig een) if yi i ie fs i i ‘ee j Uy ’ I ‘ Pe MER aA TUR ae chee : ‘ Ai wihy in on iM '. ” i i 1 4 iat) ly ) ae , nah i ’ Th oe : i) 1 i* Ue ) : 7 ee Te a, Pa ans UME Ls i; Y, ri 4 i ' i A . y i * y Figure 42 shows the pressure compensation system. No was chosen as the pressure compensating gas to avoid oxidation of motor brushes and other electronic components. Two 225 ft3 nitrogen flasks were borrowed and a scuba regulator and bleeder valve were purchased. The two back-to-back check valves, installed in parallel, were spring loaded to between 3 and 4 psi. They served to prevent the pistons from pumping out the N32 gas through the scuba valve. The internal pressure variation during a cycle was estimated as plus and minus 1.4 psi at the 500-ft depth. The maximum inertial force due to the acceleration of the water- loaded pistons was estimated to be equivalent to 2.45 psi on the two piston faces. These numbers led to the selection of plus 5 psi internal operating pressure to ensure that no force reversals would occur on the drive system during operation. The bleeder valve ensured that the internal pressure would exceed the ambient pressure by 5 psi soon after a depth change. The 5 psi differential pressure transducer was tested and the output voltage was verified to be 1 volt per psi of differential pressure. A l-ohm power resistor was installed in series with the drive power and was equipped with a low-pass filter so that the average drive current could be indicated by a dig- ital voltmeter. Figure A3 shows the arrangement of equipment used for the tests. The transducer was submerged at the end of NOSC Pier B to verify the proper operation of the pressure system. A pickup truck equipped with a shelter was obtained from Public Works to transport the equipment and author from Naval Ocean Systems Center to Bayview, Idaho and back. This saved about $1,300 of project funds that would have been spent on shipping, air fare and car rental. “PROCEDURE The test facility was closed on Monday, 19 May 1980, due to the fallout of voicanic ash from the 18 May eruption of Mt St Helens in Washington state. On Tuesday, 20 May 1980, L Teston, one of the operators, was able to get to work and we loaded the equipment on a boat and transported it to the test barge. It took about 2 hours to wash the volcanic ash from the work area, and the transducer was then rigged so that the pressure system could be submerged 11.5 feet below the axis of the pistons to supply the 5 psi of internal overpressure when the transducer was submerged. Figure A4 shows how the monitor hydrophone was suspended on a compliant support | metre from the center of the axis between the pistons. : The in-air test was performed with the pistons just out of the water but with the scuba regulator deep enough to supply most of the 5 psi overpressure. The test was repeated with the transducer at 25, 100, 150, and 500 ft. The monitor hydrophone output was re- corded on an HP 3960 FM tape recorder, and a spectrum of the monitor hydrophone output was made at each depth. The drive voltages and currents were tabulated for each depth. After the initial 500-ft test, the transducer was left running throughout the night and into the next morning fora total of 18 hours. Seven spectrums of the moniter hydrophone output were recorded during the operation at 500 ft. along with tabulations of drive voltage and current. CIES AUNT ALTOS, SO ele ESI Ne Oe ROT NR ee RR ER A A ee ee 4 be i vet Saat suum ah city nan sega 3 At: opi iM ESE Dai ur ig a my 000 ny iyi ah Wat rie vn } Ma ayn Varin! iaphieg A tSviaa ay, 225, FT? No FLASK , ADAPTER-N, TO SCUBA REGULATOR 5. No FLASK PRESSURE 2 3, 4. SCUBA DEMAND VALVE 5. BACK-TO-BACK CHECK VALVES, 3-4 PSI 6. BLEEDER VALVE 7. GAS TUBE 8. NYLON SUSPENSION 9. HAW-15 TRANSDUCER 10. OfL BLADDER 11, OIL TUBE 12. DIFFERENTIAL PRESSURE TRANSDUCER Figure A2. Pressure compensation system. SSE LY 2 WON re “a At st Earn, Ai uty mt ear * ITED SEL EEE RT Os ee Re DRIVE DRIVE VOLTAGE CURRENT oc DRIVE POWER SUPPLY + DRIVE 0-200 V oc 2—— COMMON \ CURRENT DETECTOR TV=TA AMPLITUDE POWER SUPPLY THREE LEAD-ACID BATTERIES AMPLITUDE SET OHM- .! 7.5k922MAX 1592 MIN METER DISPLACEMENT TRANSDUCER +28 V 1V=1 POUND SIMPSON } SIGNAL DIFF PRESS VM TRANSDUCER +28 V SIGNAL Geese Ee TR SPECTRAL ANALYZER TO MONITOR HY DROPHONE X-Y RECORDER FM TAPE RECORDER ss Se BARGE EQUIPMENT STRIP CHART RECORDER Figure A3. Test setup. ELE RLS TLE TI ELE SILA ES REIS ITS OLN ELS TEES I ELAS ENNIE ITTL eae il iy iV iii Ath {inher varectey Hy nil Ranh 1 ¥ Y 7 yy en { ‘ ik J if ay i yi it iy ih) y ey PUTIN Sy ! ' i rm eee i eu i i fe) Si ‘ ary : VoRy PENT | ay is a ; Pay hy a ; ; a : i i ¢ i ya ji vA : ( i} Detter ‘ eae i i hd Ra Pie ; nt i. if Ls \ Gaiaredty 4 i : f if ay ‘i i } ; i is DU tba ie fk fot fea ‘ ‘ } i i 1 diay haa athe en elec eth re iy Lb pe Sy (at ; { pale sh Treamer staeebi eben eevee at i Is WOU RN) bet: etka ie BE My ij ; ; i Ai i ay aa oy A ierwie bes i fr \ ve i aa mt ema Oe ; Pee | ahem ae RAS i dl , ¢ ‘ Or a, ; et j OE RRR ee ie Pune y D t } ; A alls deepal i ; { i aia % fal N \ Wie \ i We Wie a { hu 4 ni} i pete | Ap vee a ach RM REN fae | f \ BROOMSTICKS TOP VIEW SOFT RUBBER COMPLIANCE SIDE VIEW Figure A4. Monitor hydrophone rigging. The continuity of projector operation was shown by a strip chart recording of the rectified hydrophone signal. RESULTS Source Level MEASUREMENTS. The source level and the frequency spectrum were constant throughout the in-water tests. During the in-air test, the monitor hydrophone was used to set the frequency at 15 Hz. Figure A5 is a composite of two spectrums. The first was made with the monitor hydrophone lying on the wooden supports tied to the projector, and the second was made with the monitor hydrophone hanging from a soft rubber compliance from the same wooden supports. The compliance reduced the coupling between the hydrophone and the projector almost 40 dB in air. Figures A6 through A9 show that the frequency spectrum and source levels were the same at each depth. Figure A9 is a composite spectrum showing both the usual spectrum at full piston throw and the spectrum when the adjustable linkage controlling the piston throw was set to the extreme minimum position. Figures AlO through A16 show that the 15 Hz line did not change during 18 hours of operation at 500 ft but that some change occurred, particularly in the higher harmonic levels (slightly stronger). 30 — a — ae = a TRS) NRL TE | t ey MONITOR HYDROPHONE OUTPUT, dB re 1V MONITOR HYDROPHONE OUTPUT, dB re 1V =20 HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1128 IN AiR INTERNAL OVERPRESSURE 4.75 psi HY DROPHONE LYING ON RIGID SUPPGRTS -30 ——— — HYDROPHONE HANGING FROM SOFT RUBBER COMPLIANCE -40 -50 -60 ] iH i 70 i , | I il UF -80 f SPS ps RS 0 A A a a 0 30 60 Hz Figure AS. In-air test. 4 HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1140 25 feet INTERNAL OVERPRESSURE 5 psi -10 -20 -30 -40 ~50 Hz 100 Figure A6. In-water test at 25-foot depth. 31 MONITOR HY DROPHONE OUTPUT, GB re 1V MONITOR HYDROPHONE OUTPUT, dB re 1V -10 HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1200 100 ft INTERNAL OVERPRESSURE 5 psi Hz Figure A7. In-water test at 100-foot depth. HAW-15 TEST LAKEPEND OREILLE 21 MAY 1980 1234 250 ft INTERNAL OVERPRESSURE 5 psi 390 Hz Figure A8. In-water test at 250-foot depth. hs L ene 100 100 Sua canny tmnt i na nt , ‘ q 1 Ty F es RD Senhahiah lye Few er ie dl RE Ey HAW-15 TEST LAKE OREILLE 21 MAY 1980 1338 500 ft INTERNAL OVERPRESSURE 5 psi q $ MAXIMUM AMPLITUDE meses — MINIMUM AMPLITUDE MONITOR HYOROPHONE OUTPUT, d6 re 1V ES on an 45 60 75 90 Hz Figure A9. In-water test at $00-foot depth. maximum and minimum amplicudes. HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1415 500 ft INTERNAL OVERPRESSURE 5 psi MONITOR HYDROPHONE OUTPUT, dB re 1V Figure A10. In-water test at 500-foot depth, at test reference time, Tp. 33 af ‘aes eh MONITOR HYDROPHONE OUTPUT, dB re 1V MONITOR HY DROPHONE OUTPUT, dB re 1V -20 -30 -40 HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1510 500 ft INTERNAL OVERPRESSURE S pst Qo 15 30 45 60 75 90 100 Hz Figure All. In-water test at 500-foot depth, at TR +55 min. HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1719 500 ft wee ee ew ee 12 HZ 15 Hz ewe ee 18 HZ (Foxea w red =n, owes ese orem eas ees Ee ae > ep cm dap ee = E [> a= ox om BE ADSM GE 2seee TOE sG “4548 54 Hz a a ER i PR LRT APRN RF erent nannies ANID ES rere HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 18306 500 ft INTERNAL OVERPRESSURE 5 psi CALIBRATE SIGNALS—174 GB/piPa (FACILITY REFERENCE) et co HAW-15 LEVEL MONITOR HYDROPHONE OUTPUT, dB re 1V oe or en oe oe ee Pe Oe oe oe ee cy SS ee ane ee Figure Al3. In-water test at 500-foot depth, at Tp + 4h 15 min. -0 HAW-15 TEST LAKE PEND OREILLE 21 MAY 1980 1900 500 ft INTERNAL OVERPRESSURE 5 psi = -10 2 aQ nol 5 =) -20 a | = fe) 2 (@} -30 =I a fe) (va 5: 4 = 40 ! a fe) 5 3) i Seo tee -60 2 ERAT ) 15 30 45 60 75 30 106 Hz Figure Al4. In-water test at 500-foot depth, at Tp +4h45 min. 35 VEL ASTER TTI AE NE IOS IO ELEN MEA IGE THY SITY TDM LN TINSEL ERE ETT EATS RR ESN DP PATS LE CLS ST EPR IATA TS PNR EMG Si ETS HONE ye er ate 2 pater men seopreirsennsane renee eine ease RY Lid ehh ii, r l tw : any BeraNe een oe i ’ Av wn ‘ ayer Te ee Lap ni Daa eal hih pr ‘ f , ' : | a i Nu Jen MONITOR HYDROPHONE OUTPUT, dB re 1V MONITOR HY DROPHONE OUTPUT, dB re 1V HAW-15 TEST LAKE PEND OREILLE 22 MAY 1980 0725 500 ft INTERNAL OVERPRESSURE 5 psi 8 -10 -20 -30 -40 ! -50|_ -680 | 0 15 30 45 Hz Figure Al5. In-water test at 500-foot depth, at Tytl7 h 10 min. a0 HAW-15 TEST LAKE PEND OREILLE 22MAY 1980 0815 500 ft INTERNAL OVERPRESSURE 5 psi -10 -20 -30 4 -40 -50 ~60 tine : 0 15 30 45 60 78 so Hz Figure Al6. In-water test at 500-foot depth, at T), + 18 h 00 min. 36 a Fact et es Cae Seep Soe eure Peo SRST ames 2 She wi x yi gn OE CSE IS ACTRESS bs, ws A LTO h yo Be ; " He Rhy VOR tation indi Figure Al2 compares the acoustic intensity at three different frequencies. The frequencies, as read on the hydrophone monitor, were set by adjusting the voltage to the drive motor while the piston throw remained at maximum. Figure Al3 is the usual spectrum at 15 Hz with two calibrate signals superimposed. The calibrate signals are intended to represent the monitor hydrophone output when it is exposed to a sound pressure level of 174 dB re | wPaat 1 m. It can be seen that the 15 Hz calibrate level is | dB lower than the 19.8 Hz level. The crew explained that this was due to the diminishing response of the measurement equipment at lower frequencies. The crew established the source level of the HAW-15 projector at an apparent value of 167.5 dB re ] wPa at 1 m- This was based on a digital readout in dB of the amplified monitor hydro- phone output compared to the same readout when the 15 Hz calibrate voltage replaced the hydrophone voltage. The crew stated that they had used a hydrophone sensitivity of -203.5 dB re | Vat | wPa in their calculations. This sensitivity was based upon a reciprocity calibra- tion at | kHz. The same calibrations gave a sensitivity of -206 dB re 1 Vat 1 wPa at 10 kHz. The crew further stated that they had no way to verify the monitor hydrophone sensitivity at 15 Hz. SOURCE LEVEL CONCLUSIONS. The HAW-15 transducer radiated a constant source level at all test depths and for an ]8-hour period at 500 ft during tests at Lake Pend Oreille. After the tests the full piston-throw amplitude was measured and found to be the same as before the Transdec tests in April. The calculated sound pressure level expected to be radiated at 15 Hz and at the measured displacement was 176.88 dB re 1 Pa at I m.a little more than | acoustic watt of radiated power. The details of the calculations are in- cluded as appendix B. << “Windage”’ Loss MEASUREMENTS. One of the goals of the test program was to gain insight into the power loss due to the drag of the interior gas (in this case nitrogen) on the various com- ponents. Moving components include the motor armature, the flywheel, the linkages lead- ing to the piston faces, and perhaps the pistons themselves. Stationary components which have their effects by retarding the flow of gas caused by the moving parts include the motor stator and housing, the flywheel housing, and to a lesser degree the projector case and structural parts interfacing the gas. Figure Al7 shows the rotor drive motor input power vs depth curve resulting from the following four point measurements: A — 104.5 W at 25 ft B — 114.0 W at 100 ft C — 129.3 W at 250 ft D — 148.2 W at S00 ft. WINDAGE LOSS CONCLUSIONS. In figure A17 the input power vs depth was found to be approximately a straight line. This is to be expected since windage loss is proportional to gas density, which is, in turn, proportional to pressure, hence depth. (There is an addi- tional small increase in density with depth due to the cooler water at greater depths.) In order to separate the windage loss power from the other losses (bearing loss, motor losses and acoustically radiated power), the measured (gross) power loss curve was extrapolated from point A to the -45.5 ft point labeled E. This hypothetical point, calculated by 37 3 SS. rearrewewwcmboiaE SaeTs 4 ie ih i Vy, Bie LA NEE by Vary pur busny ae) i he Sahl Oy 1h GRE Ane Neat) Ne hig ; Pi tbvainie ie i iii , 160 MOTOR INPUT POWER, W 80 0 100 200 300 400 500 DEPTH, fr Figure A17. Motor input power vs depth (prior to bearing cun-in). accounting for the 14.7 psi atmospheric pressure and the 5 psi overpressure, represents zero internal gas pressure and hence no windage loss. [t follows that the vertical distance from the horizontal line EF to the sloping line at any depth represents the windage losses at that depth, and the value of the ordinate at line EF represents the other losses. Input Power vs Time MEASUREMENTS. The input power to the HAW-15 projector decreased appreciably during the continuous periods of operation at the 500 ft depth. Figure A18 isa graph based on the tabulations of input power. The break between 1540 and 1715 is due to a failure of shore power. No tabulations of drive current were made between 1715 and 1830 because of temporary failure of the drive current monitor. Two measurements of input power were made on the morning of 22 May (around 0800). The second measurement is considered more reliable than the first because of a number of distractions, such as changing recorder tape and calibrations, that were occurring simultaneously. The straight line con- necting the data between 1900 of 21 May and 0815 of 22 May covers the period when HAW-15 operated unattended. It was expected that a further drop in input power would be observed when HAW-15 was again operated at the surface, where the windage losses are minimum. On 29 May, therefore, the HAW-15 was operated at NOSC in the air with 5 psi internal overpressure. The initial power input was 93.5 watts, 3 watts Jess than measured in air at the beginning of the test at Lake Pend Oreille. After 10 minutes the power dropp: * from 93.5 to 79.4 watts. CONCLUSIONS ON INPUT POWER VS TIME. The HAW-15 projector required less input power with time during the prolonged tests. The initial rapid drop could be due to decreasing friction as the bearings warm up and the lubricating grease becomes less viscous. This effect might have been evident again on figure Al8 if power measurements 38 Ft err tn i A ER RN EAMES AD PRE RRL ap a RE TTI S SEIT LETTE A AITO I isl, taba VA Wet a Be he ae wane Tey ona &. iM es Pupkseey sant aye fe ay pe gp HBA aL ei hip he Pie far TEAL ASTM EAT SESS SE TOT AD OY TERRE ANEMIA 150 130 = N fo} eer cae TRANSDUCER _ OPERATING UNATTENDED INPUT POWER, W = =a (=) 100 POWER FAILURE 90 1200 1600 2C00 ooco 0490 0800 24-HOUR CLOCK TIME Figure Al8. Input power vs time. had been possible between 1715 and 1830 on 2! May. This conclusion is reinforced by the rapid drop in required input power when the in-air test was rerun at NOSC on 29 May. The lesser input power drop between 1930 on 2! May and 0815 on 22 May might have been due to further decrease in friction as the bearings were wearing in. RECOMMENDATION It is recommended that the windage loss characteristic of the projector be checked by a laboratory experiment and that the final conclusion be expressed tn the form of a windage loss equation. This equation would relate windage loss power to the combination of the type of gas, ocean depth and temperature, and overpressure within the projector. fhe laboratory experiment would compare the windage losses at measured temperatures, first with helium, then with nitrogen. These data would then be compared with the Pend Oreille results. x 39 ARN HE I eee hese me ee ern mn I ARN HM MRE TIER SIERO DR Cah BLES EL TE RSM ae Ee ENT EINE LEAR SENTRA NS APMIS! LIT BOI PSHE ESTATE RA NAGE VRE PESO ET AEE IIASA TE NIG NTT MSY GIT A EES PESO EI Pe BS ctfd Vina? ’ mind Say ey Tee vis Dane ely ! phi oy } ‘ia 7 i eae ret MP bye ned Ere ‘i MEARS De 7a rh RL Th Lea U4 AL eeconiapnied wil ys : t 3 ). pitt oe a ? rahe eed se ‘Pree ete f } Oana f FRIES reg i caeaefte APPENDIX B: NONRESONANT ACOUSTIC SOURCE OUTPUT POWER* Nava! Ocean Systems Center San Diego, California 92152 2 June 1980 MEMORANDUM From: HA Wilcox, Code 5304 To: TE Stixrud, Code 5313 : Subj: Nonresonant Acoustic Source (NRAP) output power 1. The diameter of each of the two piston faces used in NRAP is 11.25 inches. Each piston is centered in a circular aperture of !2-inch diameter. A rolling rubber seal fills the annular gap between each piston and the housing, whence it follows that the rolling seal has an-amplitude of motion which is half that of its associated piston. Hence the volume dis- placement amplitude for the combination piston plus seal is oo) 9) po) AV = (n/4)Dy°s + [(a/4oD2 - (/4)1D 5|(s/2) a) 9) ) } = (n/4) [D2 + (COZ - ID2)/2] 5. (1) where Dy = piston dia OD, = OD of seal ID, = ID of seal Ss = amplitude of piston motion (half the peak-to-peak throw of the piston). Since IDES Dp> : (2) equation (1) can be written AV = (n/4) (ODZ + IDZ)/2 5. (3) This AV is the same as for an “effective” piston diameter, Doe in the equation : a) 3 AV = (7/4)D ers, (4) ; *In this appendix the HAW-15 accoustic projector is referred to as the NRAP. i 40 { a ee rte pen cig UN OE NRE DR EAS RTS RE PECTS | bier isch rrdenere tom Yas i whence we see that 9 7 9) Doe = (ODS +IDS)/2. (5) or % : a 2 2 V/2 Doe = {(on, + ID; v2 | : (6) Putting in the applicable numbers tor NRAP, we find it: effective piston diameter to be ? ? 1/2 Doe = [22 ar, 1.252)/2| = 11.631 inches. (7) = 2. Hunter (ref B1) gives the power output formula for a small circular piston generating low frequency sound as P = 213 (p/c)f4 (A-s)-, (8) where P = average radiated acoustic power In ergs per second E % 9 p = water density in g/cm? c¢ = velocity of sound in cm/s f = frequency in Hz : : ? A = piston area in cm7 s = amplitude of piston motion in cm. For two pistens operating in phase in the breathing mode in a projector whose dimension is small compared to the wavelength of the output sound, as in NRAP, the A-s products for the two pistons must be added before using the result in equation (8). 3}, Inserting the numbers for the NRAP operating at Lake Pend Oreille into equation (8), we get P = 29 1/1.435(10)° | (1594 | (n/4) (11.6317 2.547) (0.391/2) (2.54) (2)]? (9) 1.0139( 10)! ergs per second BY Acoustics, by JL Hunter, Prentice Hall, 1957, p 147. 1.0139 watts. 4 «i, aM ‘aut tht , he Using the well-known fact that | watt re 1 wPa at 1 m is a sound level of 170.8690 dB, we can say that In our Gase P = 170.8750 dB re ! pPaat Im (10) = the NRAP source level. 4. The above Valculations are probably accurate to about 2 percent, given the uncertainties in the input data. vay wah oops apes wy Athy La fa ap ED aN Sty APPENDIX C: DISCLOSURE OF NEWLY INVENTED CAPABILITIES FOR THE NONRESONANT ACOUSTIC PROJECTOR Naval Ocean Systems Center San Diego, California 92152 2 June 1980 MEMORANDUM From: H. A. Wilcox, Code 5304(B) To: Ervin F. Johnston, Code 291(T) Subj: Disclosure of Newly Invented Capabilities for the Non- Resonant Acoustic Projector (NRAP). Ref. (a): Patent Disclosure of 14 September °*$ 3 Titled "Non- Resonant Acoustic Projector with Adjustable Frequency, Adjustable Amplitude, Adjustable Depth, Drive Mechanism," 1. On 20 April 1980 (while I was cn my recent vacation trip in the Middle East) I came up with a number of concepts for causing the NRAP (see ref. (a)) to perform in various novel and desirable ways. 2. To start with, fig. Cl shows how the amplitude of piston oscil- lation can be readily "switched," in a time very short compared with the pistons! basic period of oscillation. and in a manner which imposes essentially no impulsive loads on any of the ma- cChinery cf the projector, from full-on to full-off and back again, or between a full-off and any desired intermediate value of piston oscillational amplitude, whenever the piston has reached a turning point (i.e., a zero-velocity point) in its cycle of operation. The turning point condition occurs twice fer cycle, when the center of axle 30 passes approximately through the point ?1 on fig. Cl, and again when the center of axle 30 passes approximately through the point 40. Throughout this description, it is to be understood that axles 20 and 120 are fixed in location relative to the projector housing; also, link 100 is understood to have the Same interaxle length as link 80. A solenoid-actuated clamp is located at point 93 so that it can clamp axle 90 to a fixed posi- tion relative to the housing at that location (it is to be under- stood that other means for clamping axle 90 in the position 93 might be devised). When axle 90 is thus clamped, then as rotor 10 turns about its axle 20 whose center 21 is fixed relative to the projector housing, tne center of axle 60 is forced to follow the arcuate line of action 61 between the turning points 62 and 65. This arc of action 61 is centered on point 93, so axle 90 remains fixed and therefore cross arm 110 does not oscillate about axle 120 whose center is the point 121. Hence the piston linkages 150 and 160 do not move, wherefore the pistons 153 and 200 remain quiescent with a zero amplitude of oscillation. While the center of axle 69 is moving along the arc 61, axle 70 is censtrained by a suitable slot or other means so that its center moves along some such line of action as 71 between the turning point 73 (when the center of 60 is at 65) and the turning point 72 (when the center of 60 is eure 9 2)).5 43 Lan avi Ye rant eam | ; leva: nt: rw Hy | ie rion is OW A ae Tad 121 130 ROTOR 10 on oO Figure Cl. 44 Namen RT PE TN ne ne Sieslaeiniateneaastaandameictenanaendcneeieaiamem teen nemmnenadeentm Sinner A STARR Sesh ORK PRD lt SES If, now, when the center of axle 60 is at 65 and therefore the center of axle 70 is at 73, a suitably situated solenoid clamp or other means is used to suddenly clamp axle 70 relative to the pro- jector housing while simultaneously the clamp on axle 90 is released, then as rotor 10 continues to turn the center of axle 60 is con- strained to follow the new arcuate line of action 63 centered on the point 73. As axle 60 oscillates along 63 between the turning points 64 and 65, the center of axle 90 will be constrained to oscillate along the arcuate line of action 91 centered on point 121, wherefore the cross arm 110 must then oscillate about its axle 120 and so the piston linkages 150 and 160 must drive their respec- tive pistons in the desired oscillating manner. It is important to note, now, that the sudden switching change from a condition wnerein axle 90 is clamped at location 93 to one where- in axle 70 is clamped at location 73, does not impose any signifi- cant impulsive loads on any of the machinery of the projector, be- cause all linkages and pistons are then at or very near their zero- velocity points both before and also after the sudden switching action occurs; this is true despite the fact that the pistons are Switched at that time from a condition of zero amplitude to a con- dition of full amplitude oscillation. If and when it is desired to switch the projector back to a condi- tion wherein the pistons are not oscillating, this can be accomp- lished, again without imposing any significantly large impulsive loads on any of the machinery of the projector, by suddenly clamp- ing axle 90 while simultaneously releasing ‘the clamp on axle 70 whenever the center of axle 60 reaches its turning point 65. If it is desired to switch on the piston oscillation at a reduced amplitude of such oscillation, means are provided to bodily trans- port, without rotation, the axle 70 together with its guiding slot and clamping means, along a line from point 73 towards point 93. As 73 moves toward 93 it can readily be seen from fig. Cl that the amplitude of oscillation of axle 90 diminishes; in fact, if 73 is made coincident with 93, the amplitude of oscillation of axle 90 must vanish altogether, whence the piston motions must also vanish (i.e., the amplitude of their motion must vanish). 3. As a further invention, consider: the system shown in fig. C2. Here the elements are all the same as in fig. Cl except that (1) the interaxle length of link 80 is made significantly shorter than the interaxle length of link 100, and (2) the above-mentioned means for bodily transporting axle 70 along with its clamp and its guid- ing slot (the "transport means") is designed to be able to move the center of axle 70 along the arcuate line 74 which is centered on point 65, for example. If, now, axle 90 is clamped with qt center at point 93,the center of axle 60 must move along the line of action 61 and the center of axle 70 is forced to move along the line of action 71. However, if axle 70 is clamped with its center at point 73, then axle 60 is forced to move along the arcuate line of action we: ey) Ve vase ian op beat j finn liye werd, OF B64 Fx cv | Py eh an Watt mite ‘saint tops or Tay Meee ‘ me Ne it f r coe ihe i reed Sven Ls 240, er we ce ae va Hig cy o ie Figure C2. 16 Diba NAY atte 2 To na NOR RANON NERS I pecs 66 centered at point 73 and axle 90 is forced to move along the arcuate line of action 91. Naturally, the here-described linkages do not produce a pure sinusoidal motion of the pistons, but instead - that motion can be analyzed into its fundamental component at the rotor turning frequency plus its second, third, and higher harmonics at twice, three times, and higher integer multiples of the rotor turning frequency. If, now, axle 90 is unclamped and axle 70 is clamped, and if the transport means is thén used to move the center ef axle 70 away from 73 along the line 74, it can readily be seen that the amplitudes of the fundamental and of all odd-numbered harmonic components of the piston motion will fall as compared to the amplitudes of the second and all even-numbered components of that motion. Further, when the center of axle 76 reaches the point 67 which is equidistant from the turning points 65 and 62, the fun-~ damental and all odd harmonics of the piston motion essentially van- ish and only the second and even-numbered harmonic components of the motion remein. Hence this system is capable of varying the harmonic content of the piston motion in desirable ways, and it can in fact be used to suppress the fundamental and all odd-numbered harmonics of that motion essentially completely while continuing to put out very sizable amounts of the second and all higher even= numbered harmonics of the motion. As described in section 2 above, this system can be used to switch suddenly between the various allowable modes of motion whenever the eenter of axle 60 is at its turning point 65. Moreover, the systems of section 2 and of this section can be com- bined iby usanp a lank 80) an fie. Cl equal to) link 100 an) that) fig— ure along with a shorter link Tike that labelled 80 in fig. C2; this combination will then permit the abrupt switching of the pistons' output motion from that of the rotor frequency plus all higher harmonics to that of the second and all higher even-numbered har- monics of the rotor frequency. 4. As a yet further invention, consider the system shown in fig. C3. Here the system is the same as shown in fig. C1 except that (1) a clamp is introduced at the point 92, and (2) the linkage arm 300 is introduced along with a transport system for axle 310 and a clamp at the point 330. When axle 90 is clamped with its center at point 93, the center of axle 60 is forced to move along line 61,and the center of axle 70 must move along line 71,and the center of axle 310 must move along the line of action 320 (where 320 is determined by a suitable guidance slot, for example). If the axle 70 is clamped when its center is at point 73 while the axle 90 is then unclamped, the center of axle 60 will be forced to move along the line 63,and the center of axle 90 will be forced to move along the are 91 between the two turning points $3 and 92,and the center of axle 310 will be forced to move along the line 320 between the two turning points 311 and 330. If, next, the axle 310 is clamped when its center 47 PESTER ne SALUTE MRA ORI US RIEL RRR OIE TN EO CN ath SIO Ra ATE SSA EET OEE Figure C3. SN Ee eS ee Sa ee RD sei AA YA sit Abr 48 | | | | | L Lo i ee | ee Va 24 CUNT Onedet eermnesaigert en lehman 14 Chip tam A oe) orn e) AmSpompeibeirdda gram ow ae 4) Bens % PAS Teh nme ent anpa ara is at the point 330, and if axle 70 is then similtaneously un- clamped, the center of axle 60 will be forced to move along the arcuate line of action 340 centered on the point 330, the center of axle 70 will be forced to move along the line 74 (as.determined by a suitable guidance slot or other Means, for example), and the center of axle 90 will be forced to move along the arcuate line of action 94 between the two turn- ing points 92 and 95,where the center of the arc 94 is the point 121. The desired result of the switching operation when axle 60 has its center at point 64 is that the piston velocity oscilla- tion is then suddenly shifted by 180° in phase, again witnout producing any significant impulsive loads on any of the machin- ery of the projector. This last-mentioned switching operation can, of course, be reversed whenever the center of axle 60 is at the turning point 64. Further, suppose that axle 90 has been clamped with its center at 93, and suppose that axle 90 is suddenly released while axle 70 is clamped when the center of axle 60 is at 653; then the center of axle 60 will be forced to move along line 63 to the turning point 64. If, now, axle 70 is released and axle 90 is clamped when its center is at the point 92 and the center of axle 60 is at the point 64, then the subsequent mction of axle 60's center will be along the arcuate line of action 68 centered at point 92, and the center Of axle 70 will be forced to move along the line 74. The effect of these successive switching operations will then be readily seen to be to cause the pistons to engage in an odd number of half-oscilla- tions. This result is often desirable, especially when the odd number of half-oscillations is chosen to be the number 1. Clearly, by moving the transport mechanisms carrying axles 70 and 310 so as to bring those axles nearer to axle 90, the amplitudes of the above-described motions can be reduced individually to any desired degree, even to zero. 5. All the above-described systems can be combined to yield a Single system capable of performing any of the described operations on command. 6. In summary, the NRAP projector of ref. (a) when modified ac- cording to this disclosure has the following capabilities: (1) The rotor turning frequency, and hence all projector motions dependent on that frequency, can be quickly or slowly modulated (varied) independently of operating depth or amplitude(s) of the system. (2) The amplitude(s) of operation of the system can be quickly or slowly modulated (varied) independently of the operating depth or frequency of the system. 49 Ee ER Re A eo Baa i te ea Sa SEVEN ect PAE I SASSAFRAS ESSA TIT N SD TES LETS TS OSSD a StF Bn ar sa 0 abides A Dane Ber el er Ree i OMS Wy Le ra A ot Oe eo gobe we se aupeneg iv (3) The depth of operation of the system can be varied without significantly changing the rotor frequency or amp- litude(s) of the system. (4) The amplitude(s) of operation of the system can be near—instantaneously switched full-off if on or full-on if of f at suitably selected zero-velocity points in the motions of the linkage machinery of the system, and this switching can be accomplished without producing any signif- icant impulsive loadings on any machinery of the system.* (5) The phase of the pi-ton velocity can be near-instantan- eously switched by 180° at suitably selected zero-velocity points in the motions of the linkage machinery of the sys- ten, and this switching can be eccomplished without producing any Significant impulsive loadings on any machinery of the system. (5) The basic frequency of the piston motion can be near- instantaneously switched between the rotor frequency and twice that frequency at suitably selected zero-velocity points in the motions of the linkage machinery of the system, and this switching can be accomplished without producing any significant impulsive loadings of any machinery of the sys- tem. (7) By suitable design techniques the harmonic content of the system's piston motions can be tailored and/or varied to satisfy various postulated specifications. *In particular, the amplitude of operation of the system can be switched full on for one or any odd number of half cycles, and then the amplitude can be switched full of£ again. ec: Hightower Pickens, Stixrud, Walton 5C rrr en cc rnin SPE Om oper Teen ‘palhi i eo Rani had ee ee See eek. tian AL dayt Rea ite ; vf aay nay a : : hg ao A unitiay Aa any eu y ate oe. ar RE UNE RNAI ARREARS LEIDEN TEREST UTA LA ETA RP NIST DAES PETES AY UO A EI TNE STUY LIM TL ETI INITIAL DISTRIBUTION NAVAL ELECTRONIC SYSTEMS COMMAND ELEX-320 (LCDR PAUL GIRARD) ELEX-320 (DR. JOEL SINSKY) PME 124-60 (£. CHALKA) Aa ane RAT WET SATEIC ADI Wd UGE ASUS a is 2 sR NAVAL COASTAL SYSTEMS CENTER CODE 724 (C. M. BENNETT) CODE 721 (R. D. TURNAGE) j NAVAL RESEARCH LABORATORY ; CODE 7558 (R. DINGER) i § 4 t NAVAL RESEARCH LABORATORY UNDERWATER SOUND REFERENCE DIVISION SUPERINTENDENT (CODE 5900, J. E. BLUE) i NAVAL OCEAN RESEARCH AND DEVELOPMENT { ACTIVITY i CODE 110 (DR. RALPH GOODMAN, ; SECHNICAL DIRECTOR) i CODE 500 (DR. R. R. GARDNER) i MARINE PHYSICAL LABORATORY, UNIVERSITY OF CALIFORNIA : DR. VIC ANDERSON F. FISHER HYDROACOUSTICS, INC. P.O. BOX 3818 ROCHESTER, NY 14610 J. BOUYOUCOS UNIT X DOCUMENTS EXPEDITING PROJECT EXCHANGE & GIFT DIVISION i t LIBRARY OF CONGRESS WASHINGTON, DC 20450 } DEFENSE TECHNICALINFGRMATION CENTER (12) SERA aie mp SS RSS eS EE Sy SS TT NR {RBM RGA Melina } vi ED Ce oer on Cay ‘ ip 1 uv Vai al i Hi i, « 4 \ i) i ny) ty: i / iz i i i ; yu ss X ; i! th fh ; Y ; : (hy si j ef f in , As { i j i A \ a i i i i ; Hy le gas ; i i Mit o MY ij } i ; a ' “9 W) bath lash we prion jpeelibipharennes ¢ 5 cues 1 I fe a ts ; Ss Y i ee ‘ Miiy i: 1 , . ; y, f a! fie 5 ea i & J f - i 3 : UNCLASSIFIED PLEASE DO NOT RETURN THIS DOCUMENT TO DTIC EACH ACTIVITY IS RESPONSIBLE FOR DESTRUCTION OF THIS DOCUMENT ACCORDING TO APPLICABLE REGULATIONS. UNCLASSIFIED