ARCEBEF PTMEN. Techni-che Hogescha NAVY. DeIfL SOME INTERNATIONAL ASPECTS OF SHIP MODEL RESEARCH RESEARCH AND DYELOPMENT REPORT

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1 ARCEBEF Techn-che Hogescha NAVY PTMEN DefL HYDROMECHANCS SOME NTERNATONAL ASPECTS OF SHP MODEL RESEARCH o by AERODYNAMCS Captan E. A. Wrght, USN o STRUCTURAL MECHAN CS o RESEARCH AND DYELOPMENT REPORT APPLED MATHEMATCS Aprl 1958 Report 1220

2 SOME NTERNATONAL ASPECTS OF SHP MODEL RESEARCH by Captan E. A. Wrght, USN Reprnt of Paper Publshed by The Journal of the Amercan Socety of Naval Engneers, nc. February 1958 Aprl 1953 Report 1220

3 SOME NTER NA TONAL ASPECTS OF SHP MODEL RESEARCH THE AUTHOR s an Engneerng Duty Offcer who has served 7 years n the Tnted States Fleet, 6 years n naval shpyards, 4 years n warshp desgn, and 6 years v a naval laboratory. He s presently Commandng Offcer and Drector of the Davd Taylor Model Basn, and a member of Councl of ths Socety. EDTOR'S NOTE Proceeds from ths artcle have been deposted as a "Host Fund" for nternatonal vstors to the Davd Taylor Model Basn. Shp model research snce md-century has experenced a strong surge throughout the martme natons of the world. The purpose of ths paper s to recognze some of the nternatonal growth of possble nterest to nsval engneers. The observatons are based largely on thy nternatonal Towng Tank Conference n Madrd. vsts to most of the prncpal Euro)ean model basns, and the Symposum on Behavor of Shps n a Seaway held at the Netherlands Shp Model Basn. all durng September conclusons HAT GROWTH s evdent n the model basn busness abroad and how s the Unted States dong comparatvely? n response to ths most frequent queston, a few general conclusons are: a. Wdespread constructon of new facltes for shp model research s occurrng throughout the world. n summary, the number presently under constructon or completed snce World War s as follows: TYPE OF FACLTY NUMBER Rotatng Arm Basns 7 Seakeepng and Maneuverng Basns 8 Towng TanksNew 25 Extended 3 Shallow Water Basns and Flow Channels 12 Cavtaton Tunnels 15 From a purely plant standpont, foregn model basns momentarly lead the Unted States n rotatng arm basns, seakeepng basns, shallow water basns. and cavtaton tunnels, but current buldng at Ca'derock wll go far to restore our poston. General purpose dgtal compute's are an ndspensable adjunct to model research n the future, ard n the Unted States relatvely great progress has been made n ther applcaton. The growth of model basn facltes n assocaton wth unverstes at home and abroad s already provng ts wsdom. Shp model research n all countres s now as always wholly dependent on dedcated scentfc and engneerng personnel wth unfettered magnaton and appled enthusasm. Wthout them, funds and facltes are meanngless. Model basn professonals abroad are hghly alert, curous, cosmopoltan, modest, helpful, competent, and progressve. Much s beng accomplshed by a few. Contrbutons by the younger set n all delegatons to the conferences were partcularly mpressve. The qualty of research n all model basns vsted appeared hgh, but no more so than n the Unted States. Scence has come to naval archtecture on a fne broad nternatonal front, partcularly n stormy felds such as the wavegong aspects of seakeepng. The concurrent development of theory and experment has become ncreasngly wdespread to the beneft of generalzng results, understandng the physcal phenomena, dscplnng the nvestgators, and promotng nternatonal cross-fertlzaton n the scence of shps. The scope of model nvestgatons s beng enlarged

4 tremendously from tradtonal model tests n a straght lne to experments n 2 and 3 dmensons and up to 6 degrees of freedom. 1. The nature of model technques s lkewse expandng rapdly from steady state observatons to dynamc and transent condtons. n many countres, nadequate attenton s beng gven to observng flow condtons around models, appendages, and propulson devces. One look can often reveal more than thousands of routne measurements. A new classc (1) should do much to ncrease conscousness of the mportance of observng and studyng flow. The growng need for research n hydroelastcty, as appled to shp desgn, s begnnng to be more wdely recognzed. Several areas have been researched beyond the pont of dmnshng returns and could well be d'opped from nternatonal emphass. The Unon of Sovet Socalst Republcs contrbuted sgnfcantly to the conferences and unquestonably s one of the leadng countres n hydrodynamc research. Partcpaton n and fnancal contrbutons to shp model research abroad by prvate shp desgn and shpbuldng nterests exceeds greatly support from these sources wthn the Unted States. Here the major burden by far s carred by the Unted States Navy. Because of heavy prvate support of shp model research ab'oad, many areas of merchant shp nvestgaton are stmulated much more strongly than n the Unted States. The Unted States s stll among the leaders n shp model research but wll have to hump vgorously to retan ths poston. The nternatonal Towng Tank Conference deals solely wth professonal tankery; that s, the scence of predctng full scale shp behavor from model experments. The followng dgest has been prepared to summarze the prncpal agreements reached and objectves set at the 1957 Conference: All tank establshments wll submt detaled descrptons of ther present methods for carryng out and analyzng propulson experments, for open water p- peller experments, for estmatng shp performance, and for comparng tral results wth model predctons. From study of the many dfferent procedures, standard methods wll be recommended for general nte'natonal use. n the feld of propulson, nternatonal study wll be pursued on propeller scale effect ncludng turbulence stmulaton, on methods of determnng full scale wake factors, on propeller-'udder nteracton, on thrust deducton theory and experment, and on fluctuatons of torque and thrust. e. As the Conference favored a model-shp correlaton formula close to the 1947 Amercan Towng Tank Conference (Schoenherr) lne above a Reynolds Number of 10 but steeper at lower Rs, the followng was adopted: ( log The commttees apponted by the 1957 nternatonal Towng Tank Conference to serve and to mplement nternatonal agreements untl the 1960 conference n Pars are: Standng Commttee General R. Brard France Captan M. L. Acevedo Span Professor W. P. A. van Lammeren Netherlands Professor J. K. Lunde Norway Captan H. E. Saunders Unted States Dr. F. H. Todd Great Brtan Scale Effects On Propellers and Self-Propulson Factors Dr. Hans Edstrand Sweden Dr. Frtz Gutsche Germany U. NTERNATONAL AGREEMENTS. THE PEOPLE to be known as the 'TTC 1957 Model-Shp Correlaton Lne." n the feld of frctonal resstance, nternatonal study wll be pursued on roughness allowances, on effect of form on frctonal resstance, on mproved technques n turbulence stmulaton, and on tank boundary nterference. Propeller work wll nclude systematc nvestgatons n one or two tunnels on the effect of ar content on cavtaton phenomena, the collecton of data to enable comparson between cavtaton tunnel tests and full scale results, fundamental work on slotted wall test sectons for propeller tests, experments n dfferent tanks and tunnels on standard propellers, effect of unequal flow dstrbuton, closer coordnaton between open water and tunnel results, and the relevant propertes of water ncludng the effect of nucle and entraned ar. n the seagong qualtes of shps, the proposed studes nclude the collecton of full scale sea and shp performance data to make model tests meanngful, the development of non-dmensonal methods of presentng data for head and oblque seas, comparatve tests n waves for two geometrcally smlar models properly scaled, nterchange of nformaton on test technques n waves, and the development of theoretcal methods for desgn and evaluaton of experments. Preparaton of standard values for knematc vscosty of fresh and sea water. Mr. J. B. Hadler Unted States Mr. J. Krvtzoff U.S.S.R. Mr. L. P. Mallard France Mr. R. N. Newton Great Brtan Professor E. V. Telfer Great Brtan Skn Frcton and Turbulence Stmulaton Professor C. W. Prohaska Denmark Captan M. L. Acevedo Span Dr. George Hughes.. Great Brtan Dr. M. Knoshta Japan Dr. L. Landweber Unted States Mr. A. J. W. Lap Netherlands Dr. Karl Weghardt. Germany Comparatve Cavtaton Tests of Propellers Dr. H. W. Lerbs Germany

5 Professor L. C. Burrll Dr. J. D. van Manen. Mr. L. Mazarredo Ch. Eng. L. Pehrsson Mr. A. Slverleaf Mr. A. J. Tachmndj Seagong Qualtes of Shps Dr. M. St. Dens Dr. O. Grm Dr. H. Kato Professor E. V. Lews Great Brtan Netherlands Span Sweden Great Brtan Unted States Unted States Gerenany Japan Unted States Mr. E. C. Tupper Great Brtan Mr. G. Vossors Netherlands Mr. A. L Voznessensky U.S.S.R. Presentaton of Resstance and Propulson Data Captan H. E. Saunders Unted States Dr. E. Castagneto.. taly Mr. J. M. Ferguson Great Brtan Mr. H. Lackenby Great Brtan Mr. S. D. Mathews Canada Dr. H. F. Nordstrom Sweden Professor S. Slovc Yugoslava Dr. H. Amtsberg Germany Although laboratory facltes are forever secondary to laboratory people, ther growth has nterest and sgnfcance n that (a) they embody the deas of ther creators, and (b) they represent postve fnancal commtments of the sponsorng countres to new and extended felds of shp model research. Hence the remander and majorty of ths paper are devoted to descrpton of these more factual nternatonal aspects. ROTATNG ARM BASNS A strkng development of the current decade s the ncreasng ablty to predct the course keepng qualtes of shps and submarnes, and ther paths under the nfluence of control surfaces. The predcton technque depends presently upon the expermental determnaton of hydrodynamc coeffcents for the body and ts appendages, the substtuton of V. PHYSCAL GROWTH tons. The rotary coeffcents of moton are best obtaned by towng the body n a crcular path and treasurng the forces thereon. The frst large rotatng arm basn desgned for the purpose was completed by the French at the Bassn d' Essas des Carenes n Pars n 1945 (2). Ths crcular model basn, 213 feet n dameter and 16 feet deep, has an arm pvoted n the center and rollng at ts outer end on a crcular track, Fgure 1. Two 25 HP motors wth Ward-Leonard control drve the outer end of the arm through two rubber-tred wheels at speeds up to 19 knots. The new large towng basn n Pars completng n 1958 connects wth the rotatng arm basn to permt rado-controlled Courtesy of the Drector Fgure 1. The Rotatng Arm Faclty at the Bassn d'essas Des Carenes n Pars. The end of the arm to the left n the photograph s pvoted on an sland n the center of the basn, and the rght end s drven around a perpheral track by the tn&. motors whose hoods can be seen. The overhead catwalks are used for photography. thes coeffcents n the dfferental equatons of moton, and the calculaton manually or by analog computer of the flght path under dfferent cond- Courtesy Mr. F. S. Burt Fgure 2. Rotatng Beam Basn Under Construoon at the Admralty Research Laboratory. All concrete s heavly renforced, partcularly the footng for the 16-foot dameter concrete base requred to support the kngpost wthn 8 seconds of arc to the vertcal. turnng models a long straght acceleratng run before the rudder s lad over. A rotatng arm was nstalled n the 75-foot square, 4.5-foot deep, maneuverng basn at the Stevens nsttute of Technology near the close of World War, and much poneerng work on the steerng and turnng of shp models has been done n ths faclty. At the Admralty Research Laboratory, Teddng-

6 ton, England, a rotatng-beam channel (3) has recently been completed and embodes spectacular engneerng performance. The annular channel, shown under constructon n Fgure 2, has an outsde dameter of 136 feet, a depth of 15 feet, and s 34 feet wde. Spolers and beaches nhbt currents, wave reflectons, and hydraulc resonance. The rotatng beam, Fgure 3, s supported and drven at the center only. The beam moves at a maxmum perpheral speed of 90 knots at the 50-foot radus, whle supportng a model weghng 3,000 pounds and creatng a drag force of 4,000 pounds appled 5 feet below the water surface. Centrfugal acceleraton s 14g. Underwater, large pcture wndows, whch f broken wll be closed automatcally by steel shutters, provde comfortable observaton statons. At the Admralty Experment Works, Haslar. England, whch serves the same shp desgn needs for the Brtsh Navy as the Davd Taylor Model Basn does for the U. S. Navy, extensve constructon s underway for new shp model research. A rotary arm faclty wll form a part of a large maneuverng and seakeepng basn (4) now buldng. The maneuverng basn at the Hamburgsche Schffbau Versuchsanstalt s 82 feet n dameter and tangent to the man towng tank at one end. Ths lr.. - 1lr_. -._,- = ==. Courtesy M. F. S. Bu,t Fgure 3. Rotatng Beam Basn Completed at the Admralty Research Laboratory. Through the hghly-fltered water can be seen the swrl plates radally n the basn floor and the vewng ports n the sland. The 122-foot symmetrcal beam weghng 60 tons rotates at speeds up to revoluton every 2 seconds. arrangement provdes a straght acceleratng run under the towng carrage before the model goes nto a turn, lke the "J" basn at Carderock. The Hamburg tank s ftted wth a rotatng arm. - Offcal U. 5. Navy Fgure 4. Arrangement Model of Rotatng Arm and Maneuverng Basns Under Constructon at Carderock. Except for housng under the same roof, wth au open span of 274 feet by 692 feet. the basns are physcally and functonally separate wth the maneuverng basn to the left n the photograph and the rotatng arm basn to the rght. 4

7 The rotatng arm faclty under constructon at the Davd Taylor Model Basn wll be housed wth, but entrely separate from, the new maneuverng basn, Fgure 4. To permt usng the same standard 20-foot model throughout all the varous tests at Carderock, the crcular basn wll be 260 feet n dameter wth a water depth of 20 feet (5). The 38,000-pound, tubular alumnum, rotatng arm wll be drven by two 250 HP motors through 30-nch steel wheels rollng on a perpheral steel track. The arm s desgned to accelerate from rest to 30 knots at the 120-foot radus n ½ revoluton to permt readngs on surface shp models before they overtake ther surface wave system. Maxmum arm speed at the 120-foot radus wll be 50 knots. A 20- foot submarne weghng 2600 pounds held by struts 10 feet below the water surface can attan a 12 knot arm speed wthn one-half a turn for any radus between 48 and 120 feet. On the undersde of the rotatng arm, there wll be a small carrage whch can be remotely controlled to poston the model n radïus. roll, ptch and yaw. SEAKEEPNG AND MANEUVERNG BASNS Worldwde scentfc attenton s beng brought to focus or the seakeepng qualtes of surface shps. At the Symposum n the Netherlands, 45 mportant techncal papers coverng every aspect of wavegong were presented; among the authors were representatves of the Natonal nsttute of Oceanography n Great Brtan, Unversty of Tokyo, A. N. Kryloff Shpbuldng Research nsttute of the U.S.S.R., Stevens nsttute of Technology, Unversty of Calforna, Hamburgsche Schffbau Versuchsanstalt, Transportaton Techncal Research nsttute of Japan, Massachusetts nsttute of Technology, New York Unversty, Techncal Unversty Berln-Char- -Courtesy Professor W P. A. von Lammeren Fgure 5. Frst Seakeepng Basn. created by the Netherlands Shp Model Basn. The angles and complexty of the waves are vared by snake-type generators along (he left sde n the photograph and at the far end. The towng carrage runs n a fxed drecton on the rals whch can he seen through the rght hand row of columns. lottenburg, owa nsttute of Hydraulc Research, Kng's College, Netherlands Meteorologcal nsttute, Royal Netherlands Navy, Unversty of Treste, Natonal Physcal Laboratory, Delft Shpbuldng Laboratory, Natonal Research Councl of Canada, Netherlands Shp Model Basn, Stanford Unversty, Lenngrad Shpbuldng nsttute, and Davd Taylor Model Basn (6). Shp model research n seakeepng calls for controlled tests not only n regular head and followng waves as has been the practce, but also n rregular and short-crested waves at varous angles of encounter. Consequently a new type of model basn s needed. The Seakeepng Laboratory of the Netherlands Shp Model Basn (7), completed n May 1956, s the frst faclty n operaton for shp model tests n a wde spectrum of smulated sea condtons. n the snake type wave generators, elements 2 feet wde can be phased to send out wave trans n a wde choce of drectons and crest shapes, Fgure 5. Then, wth such wavemakers on two adjacent sdes of the basn, patterns of rregular short-crested waves can be obtaned. Consequently, the towng carrage need run only n a fxed drecton. The 9- ton carrage s drven up to 10 knots by 3.7 HP motors to each of four 39-nch wheels on rals supported by two rows of pllars for the length of the 328-foot basn. The basn s 80 feet wde and 8 feet deep. The models, 10 to 13 feet n length, are selfpropelled and ftted wth automatc steerng gear. The Stevens nsttute of Technology has put nto operaton a plunger type of wavemaker along one 75-foot sde of ther square maneuverng basn (8). Long-crested regular and rregular waves wll be generated prmarly, wth provson for short-crested seas by temporary local extensons of the wavemaker face. A brdge, whch can be postoned across the basn at varous angles to the wave system, wll carry on the undersde a lght towng carrage. Models approxmately 4 feet long are contemplated. At Feltham 5 mles from Teddngton, the Natonal Physcal Laboratory s buldng a completely new Shp Hydrodynamcs Laboratory, Fgure 6, wth all of the balanced components and facltes for the operaton and support of modern shp model research (9). ncluded n the constructon s a maneuverng and seakeepng basn, 100 feet square by 8 feet deep, Fgure 7. Along one wall s beng provded a contnuous plunger type wavemaker, wth a deep hollow-faced wedge, to generate waves up to 15 feet long and 9 nches hgh. Later an artculated plunger-type wavemaker wll be added along an adjacent wall to supermpose waves at dfferent angles on the man pattern. Free-runnng, rado-controlled models n the order of 10 feet long are contemplated for both maneuverng and wavegong tests. Anrouncenent was made at the 1957 nternaton-

8 Courtesy Superntendent. Shp Dvson Fgure 6. Model of Man Buldng Group of the New NPL Shp Laboratory at Felham, England. The maneuverng basnshop group s to the left, the new deep water basn n the center, and the cavtaton tunnel buldng to the rght. Courtesy Superntendent. Shp Dvson Fgure 7. Maneuverng Basn Under Constructon at Feltham. The wax model storage and transfer tank n the background wll connect the model shops and tse man towng basn. al conferences that the Admralty Experment Works at Haslar has under constructon a large seakeepng and maneuverng basn. Prncpal dmensons wll be a length of 400 feet. a wdth of 200 feet. and a water depth of 18 feet. Plunger type wavemakers wll be nstalled at one end and along one-half of the long sde of the basn. n Canada, the Natonal Research Councl at ts model basn at Ottawa s constructng a large maneuverng basn 400 feet long by 200 feet wde by 10 feet deep. Wavemakers may be added n the future. At the Techncal Research nsttute n Tokyo, --Offcal U. 5. Navy Fgure 8. Constructon of DTMB Seakeepng and Maneuverng Basn. The seakeepng basn wll be at the far end; holes for the pneumatc wavemaker ducts can be seen near the tops of the basn walls. The rotatng arm basn wll he at the near end; the center support can be seen to the rght n the photograph. self-propelled models 26 to 28 feet long n whch or 2 men rde are tested for maneuverng qualtes. The basn s shaped lke a rght-angled trangle, over 600 feet on one leg and 440 feet on the other leg, wth a depth of 20 feel. A 60-foot tower n the Center s used to photograph the model paths. The U.S.S.R. delegaton to the nternatonal Towng Tank Conference announced the constructon of a tremendous new open maneuverng and seakeepng basn (10). Ths faclty wll have a wdth 6

9 of 230 feet, a length of 558 feet, and a depth of 18 feet. Plunger type wavemakers for ths basn are under constructon and nearng completon. At the Davd Taylor Model Basn, as at the Admralty Experment Works, the physcal dmensons of the maneuverng and seakeepng basn were selected so that models of the standard length could be tested. The rectangular basn therefore has a length of 360 feet, wdth of 240 feet, and depth of 20 feet over most of the floor area, Fgure 8. Parallel to a long wall, a 50-foot wde trench s beng provded to have a water depth of 35 feet for testng free-runnng, submarne models and for observng them through wndows n the wall. The wavemakers wll be pneumatc, run the length of two adjacent walls, generate waves up to 40 feet long and 2 feet hgh, and absorb about 2500 HP at maxmum load. Consderable flexblty s beng bult nto operaton and control of the wavemakers to permt creaton of a wde range of controlled sea condtons. The hghly effectve grd type beach desgn s the result of exhaustve experments at the St. Anthony Falls Hydraulc Laboratory. Spannng the length of the basn, and movable between runs to angles from O to 45 degrees to the basn axes, s a 376-foot brdge weghng about 230 tons whch carres an alumnum towng carrage on ts undersde. The carrage wll have a maxmum speed of 15 knots, wll accelerate up to 04g by the tractve effort of rubber tres drven by two 30 HP motors, and carry operatng personnel, c ntrols, and nstrumentaton for constraned and free-runnng models. n addton to specalzed seakeepng model basns, many laboratores are provdng or mprovng wave makng and absorbng equpment n ther man basns. These wll be descrbed under the secton or Towng Tanks. The valdty of seakeepng predctons from shp model tests must frst be establshed by correlaton wth precse observatons of full scale shp behavor under known sea condtons. n preparaton for such correlatons, a number of seakeepng trals are n varous stages of completon. The Royal Netherlands Navy and the Davd Taylor Model Basn, asssted by the nsttute of Appled Physcal Research n Delft and the Unversty of Ghent, have conducted extensve seaworthness trals on the destroyers HNMS Fresland, Zeeland, and Everstsen (6). Smultaneous measurements were made of roll and ptch angles; transverse, longtudnal and vertcal acceleratons, hull stresses n deck and keel, and bottom pressure at 8 statons along the length. The U. S. Martme Commsson, Bureau of Shps, and Davd Taylor Model Basn are conductng seakeepng trals on two 6,000 HP Lberty shps, one of whch has been lengthened 25 feet and the forebody consderably fned. Not only are the shp motons and acceleratons beng measured concurrently and comprehensvely, but also the sea state wth equp- ment developed by the Brtsh nsttute of Oceanography at Wormley. These shpborne meters correct statc wave pressure readngs for roll of shp and for heave by double ntegraton of accelerometer sgnals. The Swedsh Shpbuldng Research Assocaton and the Davd Taylor Model Basn are collaboratng on full scale stran and moton observatons n the hgh-speed cargo shp MS Canada. Several round trps have been made from Sweden to Vancouver. and jont analyss of the observatons s beng undertaken. Shpbuldng Research Assocatons n Great Brtan and a number of other countres are engaged n exploratons of ths knd. The U.S.S.R. has developed consderable nstrumentaton for full scale trals, ncludng gyro-recorders for shp motons, pressure gages for hydrodynamc loadngs, and stran gages for measurement of hull stresses (10). Durng full scale trals under a varety of sea condtons, waves are measured by wave pole, by buoy and by stereophotography. The buoys are equpped wth rado telemeterng apparatus for transmttng nformaton to shpboard on wave heghts and perods. The subject of Dynamc Forces and Moments n a Seaway was ncluded n the formal agenda of the nternatonal Towng Tank Conference for the frst tme n Ths step recognzes that study of elastc responses n a shp, such as strans, acceleratons, pressures, and vbratons, depends bascally on ncreasng knowledge of the exctng hydrodynarnc forces. Conversely, these forces can be markedly effected by the elastc character of the nterface. Under the sponsorshp of the Bureau of Shps and techncal cognzance of the Davd Taylor Model Basn, nstrumentaton has been devsed and tests run by the Stevens nsttute of Technology on a destroyer model n waves. Not only the bendng moment but also the shear amdshps was measured, and t has been possble to reproduce n the model the 2-noded natural hull frequency correspondng to ths vertcal vbraton characterstc n the shp (10). Ths poneerng technque was ntally trggered by the Socety of Naval Archtects and Marne Engneers. Loadng studes on shp models n waves, undertaken for the frst tme n Japan, are now also done at the Massachusetts nsttute of Technology, Vckers-Armstrong n St. Albans, and others. Delft Techncal Unversty uses a plastc model, rather than a splt model, and fnds t convenent for observng hull strans n any drecton. The Kryloff Shpbuldng Research nsttute at Lenngrad studes forces on a shp model n a seaway by measurng pressures on the hull, by strans produced n a splt model, and by measurng acceleratons. TOWNG TANKS The Drector of the Canal de Experencas Hdrodnamcas at El Pardo was Charman of the Stand- 7

10 Courtesy Dr. -1. W. Lerbs Fgure 9. Hamburg Model Basn Complex of Facltes for Medum Szed Models. From the left can be seen the cornhned shallow water basn and flow channel, the monoral towng carrage whch serves the basns on each sde, the maneuverng basn wth rotatng arm projectng, and the man basn. ng Commttee of the nternatonal Towng Tank Conference and host to the Eghth Meetng held n Madrd. Through hs most thorough and hosptable arrangements, 96 model basn drectors and delegates from 21 natons met n valuable techncal sessons coverng many aspects of tankery. The reports, dscussons, decsons and recommendatons are beng dstrbuted by the Spansh Organzng Commttee. Durng the Conference, opportunty was provded to vst and to see n operaton the complete facltes at El Pardo. The man towng tank was lengthened 360 feet n 1946 to a new length of 1050 feet. The orgnal cross-secton, 41 feet wde by 21 feet deep, was retaned throughout. One of the most remarkable laboratory advances of ths decade s occurrng at the Hamburgsche Schffbau Versuchsanstalt n Western Germany. Wth the pre-war basns n runs, a completely fresh start has been made n another secton of the cty. Snce openng n 1950, over 820 shp models and 560 propeller models have been made and tested. ntally at Hamburg, a compact complex of flexble medum-szed facltes has been bult, Fgure 9. The man towng tank s 260 feet long, 16 feet wde and 10 feet deep for testng models about 15 feet long. When the portable plunger type wave generator s nstalled n the fttng dock end of the man basn, the water level s dropped below the fxed sde beaches and wave quashng screens are lowered nto the water between runs to reduce the watng nterval. The maneuverng basn s at the opposte end of the man tank. Unque among model basns, as far as known, s the monoral desgn of towng carrage at Hamburg. Or the upper ral, supported by the renforced concrete roof, run only carrage gude wheels. The lower ral carres gudng, weght, and tractve forces. Generators on the carrage supply the two man drvng motors as well as the model under test. Maxmum carrage speed s 7 knots; an ndependent wre towng arrangement s also provded over ths basn for tests up to 12 knots. The monoral carrage travels between the shallow water basn and the man basn, overhangng both. Hence unobstructed vews and photographs of the models under test can be obtaned opposte the towng carrage. New large facltes are under constructon at Hamburg. The model basn, Fgure 10, was flled for the frst tme n March 1956, and algnment of the rals s well advanced. The basn cross-secton of 59 feet by 20 feet wll provde an exceptonally large hydraulc radus. The present length of 656 feet s extensble to 1480 feet f requred n the future. Ral layng s well advanced. The new towng carrage wll be a massve precson nstrument of hghly orgnal desgn. ts antcpated structural weght s 15 tons, total weght 26 tons. Four large wheels over 4 feet n dameter, each motor drven through gears, wll propel the carrage at speeds up to 20 knots. Track brakes wll grp the ral' head for emergency stoppng at any pont, as at Carderock. Wthn the large rectangular bay of the man towng carrage, a secondary carrage wll run athwartshps, makng pos'ble n effect concurrent moton n both the X and Y drectons. Thus t wll he possble to execute zgzag maneuvers, and to run a model wth waves on the bow and quarter as well as dead ahead and astern. The undersde of the carrage s well elevated above the water surface. A plunger type wavemaker s planned. These fne new facltes at the Hamburgsche Schffbau Versuchsartalt are expected to commence operaton by late Sprng At the Bassn d'essas des Carenes n Pars (11), an equally mpressve new model basn and towng carrage are n a comparable stage of constructon, Fgure 11. Ths large basn has a cross-secton 40 feet wde by 15 feet deep, and a length on the water courtesy Dr. H. W. Lerbs Fgure 10. Wdest Model Basn Spanned by a Towng Carrage. nearng Completon at the Hamburgsche Schffbau Versuchsanstalt. Above the fttng basn n the foreground can be seen the truss members of the new towng carrage and, at the extreme left and rght, the large carrage drve wheels.

11 Courtesy of the Drector Fgure. New Deep Water Basn and Carrage at the Pars Model Basn. Two of Ehe Four carrage drvng unts and a set of gude wheels can be seen. 'he stff tubular constructon s partcularly well desgned. of 722 feet. t connects through double watertght gates to the crcular maneuverng basn so that approach runs can be obtaned. The watertght gates also provde a drydock wthout dsturbng operatons n ether basn. The tubular carrage structure, wth as many as 10 members joned at a sngle sphere, wll he one of the sturdest and stffest n exstence, attrbutes whch are extremely mportant Courtesy r. Jole Gerrtsrna Fgure 12. New Facltes of the Unversty of Technology at Delft. To the left s the man tank and towng carrage: to the rght s the combned shallow water basn and flow channel, also equpped wth a carrage. Courtesy Mr. W. A. Crugo Fgure 13. New Tank and Monoral Carrage Opened at Saunders-Ree n All carrage optratons are controlled from and readngs are transmtted to the console n the foreground. 9

12 n these days of dverse unforseeable demands for surface and subsurface experments. The carrage s trapezodal n overall plan form, and all drvng and gudng are done from the same heavy ral. Four drve motors wll propel the carrage at a maxmum speed of 20 knots. An open dynamometer bay wll provde great flexblty and economy n carrage tme by rggng nstrumentaton for a partcular test on shore and then lftng the entre assembly nto the dynamometer bay. Wndows for underwater vewng are set nto the basn walls. t s expected that ths fne faclty wll be n operaton before the end of 1958, and wll be a hghlght of the next nternatonal Towng Tank Conference beng planned for Pars n The frutfulness of havng a model basn as a part of a school of naval archtecture has been wdely recognzed and utlzed. n Holland, the teamwork s carred to 3-way collaboraton between the Netherlands Shp Model Basn, the Unversty of Technology at Dell t, and the Shpbuldng Laboratory of that Unversty. Excellent new facltes for nstructon and research n naval archtecture have recently been completed at Delft (12). The towng tank has a length of 316 feet, and a rectangular cross-secton 14 by 8 feet. A pneumatc type of wave generator produces not only regular waves, but also can be externally programmed on a plug board, lke some new types of console calculatng machnes, to produce a wde varety of rregular waves. Blower power up to 25 HP supplyng ar to the plenum dome wll generate waves wth perods to 2 seconds, lengths to 20 feet, and heghts to 11 nches. Delft's towng carrage, weghng 5 tons, s propelled at speeds up to 15 knots by four 5 KW motors drvng each of four 23-nch wheels, Fgure 12. Complete nstrumentaton for resstance, propulson, open-water propeller, and wavegong tests are carred, together wth a wre-re;stance type of wave heght meter. When self-propellng n waves, a small lght secondary carrage provdes full freedom n surge, ptch and heave, and tests of a DTMB Seres 60 model n a head sea were wtnessed wth admraton. On the return run of the carrage when testng n waves, a wde board extendng the wdth of the tank s lowered onto the water surface, and lïterally rons out the resdual waves. The model basns at Saunders-Roe Lmted on the sle of Wght are engaged n a wde spectrum of scaled dynamc nvestgatons, all the way from the hydrodynamcs of sk-supported seaplanes and the dtchng of every class of arcraft to tests of mnesweepers, hydrofol boats, and all types of surface craft. The orgnal 618-foot basn completed n 1946 has a towng carrage that attans a speed of 35 knots. Forced rollng and fn stablzaton tests were underway at the tme of vst. The second tank was opened n June 1956 (13). Here, from the monoral carrage, 14 nstantaneous observatons can be transmtted through a looped multcore cable to the control console, Fgure 13. A 10 HP wnch drves the lght carrage at speeds up to 30 knots. Tank dmensons are length 250 feet, wdth 12 feet, and depth 6 feet; the cross-secton s rectangular. The new tank has been ftted wth a wavemaker of the plunger type and tests of a hgh speed surface craft n waves were observed. The Stevens nsttute of Technology has been conductng sea-keepng experments n ther orgnal towng tank, now ftted wth a programmed generator for rregular waves. n Berln, a pneumatc type of wavemaker, that generates from the acton of ar sucton as well as ar pressure on the water surface n the dome, has now been put nto operaton. At Feltham, the large new towng tank of the Natonal Physcal Laboratory had just been flled at the tme of vst and track layng of all-welded rals was begnnng. The generous cross-secton of the tank, 48 feet by 25 feet, was determned by the desre to test larger self-propelled models, of the order of 24 feet long (9). Shop machnery s planned to process wax or wood models up to 40 feet n length. The towng carrage s desgned for a 7- second steady run at 30 knots on a tank length of 1300 feet. The man tank, Fgure 14, s almost entrely above ground level. The Dansh model basn s now under constructon at Hjortekaer just north of Copenhagen, Fgure 15. The man tank wll have a length of 788 feet, a wdth of 39 feet and a depth of 18 feet. t wll be flled n the late Sprng of 1958 and track layng wll begn. The towng carrage s already under constructon. The new plant wll also nclude an aerodynamc laboratory. n North Amerca, the Natonal Research Councl of Canada completed a new model basn n ts Dvson of Mechancal Engneerng at Ottawa n The tank s 450 feet by 25 feet by 10 feet (14). A 30 HP drve motor propels the towng carrage at speeds Courtesy SupeTntendent. Shp Dvson Fgure 14. Deepest Model Basn Spanned By a Towng Carrage, part of the New Feltham Complex of the Natonal Physcal Laboratory. Roof structure and sde panelng are all of alumnum. gvng a strkng appearance to the nteror of the long basn buldng. 10

13 Courtesy Professor C. W. Prohaska Fgure 15. Fne New Facltes for Denmark are under Constructon. Vew of eastern end and part of workshops. up to 12 knots. MT's 108-foot tank was put nto operaton n February 1951 (15). A programmed wave generator has now been added. The Robnson Model Basn at the Webb nsttute of Naval Archtecture was also completed n The U. S. Naval Academy at Annapols now has a towng tank for the nstructon of mdshpmen (16). The tank s 52 feet by 6 feet by 4 feet, and s ftted wth a gravty dynamometer and electronc speed calculator. The new tank of the Unversty of Calforna at Rchmond became operatonal n the Fall of t s 200 by 8 by 6 feet, has both towng carrage and wave generator, and s beng used for a varety of research ncludng shp motons (17). Convar Dvson of General Dynamcs at San Dego has a new 300-foot tank (18) as a part of ts growng hydrodynamcs laboratory. The planned facltes contemplate a second 300-foot tank n lne wth the frst, and wth a 100-foot square turnng basn between them. The lght monoral carrage can be operated up to 60 knots. n an extenson of 302 feet was made to the Courtesy of the 5uperntendent Fgure 16. Completely Modernzed Orgnal Tank at the Admralty Experment Works. The new carrage s drven by a synchronous motor at each corner. 35 by 18 foot man tank at the Netherlands Shp Model Basn, makng the present length on the water 827 feet. The orgnal tank at the Admralty Experment Works was lengthened n 1957, together wth new shops and drawng rooms n the extenson (4). The tank s now 540 feet long by 20 feet wde by 9 feet deep. The wooden box grder towng carrage desgned and bult by Wllam Froude has now been replaced by a completely new towng carrage, Fgure 16. t s remarkable that the orgnal Froude paddle type wavemaker was n such good condton that t was largely relocated at the extended end of the basn; waves up to 1 foot hgh and 20 feet long can be generated. The new tank under constructon n nda s understood to be about 500 feet long, wth a 12 by 7 foot cross-secton and wth a carrage speed up to 12 knots. The Genoa tank, completed n 1947, s 158 feet long, 9 feet wde and 5 feet deep. n late 1953, excavaton started for the stanbul Model Expermental Tank as a component of the Turksh Shpbuldng and Research nsttute founded the same year (19). The towng tank s 245 feet long wth a cross-secton about 20 feet wde and 12 feet deep. The carrage, weghng approxmately 9 tons, wll be propelled up to 14 knots. The Kryloff Shpbuldng Research nsttute n Lenngrad s unquestonably dong mportant scentfc work n shp model research, as well as accomplshng an mposng amount of resstance and propulson testng, n support of an extensve shp desgn and buldng program (20). The man tank there s so long, n the order of 2130 feet, that a number of readngs at dfferent speed settngs can be obtaned n one trp down the basn; ths tank s 50 feet wde and 23 feet deep. The second tank s 490 feet by 20 feet by 13 feet. Both towng tanks at Lenngrad have now been equpped wth eccentrc rotatng drum type wavemakers. The tanks are apparently workng a full 16 hours daly, and the large professonal staff of perhaps 150 to 200 s very actve. Russan representatves of the Kryloff nsttute and of the Academy of Scences n Moscow made sgnfcant techncal contrbutons to both the Wagenngen and Madrd conferences, and wll n the future be represented on the techncal commttees of the nternatonal Towng Tank Conference. n Brazl, the Naval Secton of the Techncal Research nsttute has recently completed at Sao Paulo a shp model testng tank 197 feet long, 12 feet wde and 7.5 feet deep (21). The towng carrage for ths new faclty corresponds to those of larger basns, for t s desgned to undertake propeller and selfpropulson as well as resstance tests, and to carry model testng personnel and the carrage operator. The rectangular 20 by 13 foot carrage weghng about 4 tons wll have a speed range up to 10 knots. The Mtsubsh model basns at Nagasak, destroyed by the bomb, have now been completely 11

14 rebult and n full operaton snce August 1953 (22). Prncpal features are: Medum Tank Large Tank Length, feet Wdth, feet Depth, feet Carrage drve, HP Speed, max., knots Models, max., feet The two tanks are n tandem so that the large towng carrage can run the length of both tanks. A 30 HP wavemaker serves the large tank. Fgure 17. Courtesy Hdeo Fujta Fgure 17. The Mtsubsh Nagasak Expermental Tank. Carrage and housng have been completely rebult: the flap of the new wavem.aker can be seen n the foreground. Extensve constructon of new facltes s currently underway at the Meguro Model Basn of the Techncal Research nsttute n Tokyo. Completed n 1956, the small basn s 336 feet long by 11 feet wde and 7 feet deep, wth a towng carrage drven up to 14 knots by four' 7.5 HP motors, Fgure 18. A pneumatc wavernaker for ths basn was completed Courtesy M. Kanno Fgure 18. Small Tank at the Meguro Model Basn. Auxlary pneumatc tres are used on concrete rals at both tank ends for hgh acceleraton and deceleraton. n The large basn, 836 feet long wth a crosssecton 41 feet by 24 feet, s n the ral layng stage, Fgure 19. The steel-tube all-welded towng carrage wll be 52 feet long, wll wegh 30 tons, and wll be drven up to 32 knots by four 35 HP drve motors. A flap-type wavemaker, drven by a 100 HP motor and capable of generatng waves over 3 feet hgh, has been nstalled n the large basn. Lkewse buldng s a thrd basn 1140 feet long, 20 feet wde and 10 feet deep for stll hgher speed experments. At Kngs' College n the Unversty of Durham, a tank 130 feet long wth a cross-secton 12 by 5 feet was completed n July 1952 (23) for research and nstructon n the Department of Naval Archtecture, the frst arrangement of ths knd n England. Snce November 1951, full operatons have been resumed n the Schflbautechnshe Versuchsanstalt n Venna, Fgure 20. The basn s 590 feet by 33 feet by 16 feet, and the maxmum carrage speed s 15 knots. Ths basn was heavly damaged n World War. At the Shpbuldng Research nsttute n Zagreb, Yugoslava, extensve constructon s underway. Of the 4 new model basns now buldng, one wll be a deep water basn about 905 feet long, 40 feet wde by 21 feet deep, and another a hgh speed basn almost 1000 feet long wth a cross-secton 16 by 10 feet and a carrage speed of 40 knots. Detals wll be announced at the tme of openng, probably next year. Consderable progress s beng made n the development of technques and ostrumentaton for resstance and propulson experments on submerged bodes n towng tanks, such as at the Natonal nsttute for the Study and Testng of Naval Archtecture n Rome, Fgure 21. SHALLOW AATER BASNS AND FLOW CHANNELS Channels at model basn establshments appear to be of three general varetes: (a) Shallow water basns n whch the water s at rest and the towng carrage moves, (b) channels usng ether a carrage or flowng water or both, and (e) facltes desgned for observng a statonary model n movng water. The Pars Model Basn completed and put nto operaton n 1956 a separate shallow water basn wth depth from O tu 6.5 feet, utlzng the basn floor as was done at Carderock. Ths basn s 508 feet long and 30 feet wde, and wll be used for maneuverng experments n shallow water as well as resstance and propulson, Fgure 22. The towng carrage has a maxmum speed of 10 knots. A gate type wavemaker was ready for nstallaton when ths tank was vsted. Another new addton to the Netherlands Shp Model Basn wll be facltes for nland waterway tests and research (24). Constructon s now well underway on ths basn. Fgure 23, whch wll be 712 feet long. 52 feet wde and 4 feet deep. Expermental work n ths basn s already programmed over ts frst 5 years. At Dusburg-Neudorf n Western Germany, Specal facltes were bult about 1954 for the study of 12

15 Courtesy M. Kanno Fgure 19. New Large Meguro Tank of the Techncal Research nsttute, Japan. Completon of the rals, carrage and dynamometer s antcpated n Courtesy Dr. Leopold Kretschmer Fgure 20. War Damage Now Repared at Orgnal Gebers Tank n Venna. Courtesy J. Puglese Fgure 21. Towng Tests of a Submarne Model at the Rome Model Basn. Dynamometers have been bult for selfpropulson experments on submerged bodes. 13

16 Courtesy öl the Drector Fgure 22. New Shallow Water Basn at Pars. A large towng carrage, complete wth nstrument room, s provdcd entrely for shallow water. craft for nland waterways. The shallow water tank there s 130 feet long and 10 feet wde wth a towng carrage. n addton, there s a large shallow tank Courtesy Dr. W. P. A. van Lammeren Fgure 23. The Netherlands Bulds a Shallow Water Model Basn. A new maneuverng pond s n the background. whch, after the second stage of constructon, wll be 360 feet long. The Deft flow channel (12) has a length of 147 feet, a wdth of 9 feet, and a depth over an accuratelylevelled bottom varable from O to 1.6 feet. A carrage over the channel wll tow at speeds up to 5 knots n ether drecton. The water can be made to flow up to a velocty of 2 knots n the channel. The water crculates n a flat vertcal loop, mpelled by a 4-hladed 30 HP propeller. The Hamburg combned shallow water basn and flow channel shares the use of the double-cantlevered towng carrage. The water depth s adjustable up to 2.2 feet n the channel of wdth 12 feet and length 262 feet. When at maxmum secton, a water flow of 2 knots can he obtaned. Studes of the Baltc to North Sea Canal were underway at the tme of vst to Hamburg. The flexblty to adjust the channel dmensons, water speed, and model speed n a faclty of ths knd s a materal advantage n restrcted waterway experments. The flow channel at Pars has large stllng reser-

17 vors both upstream and downstream of the channel to stablze end condtons. Water s transferred between reservors by 4 hydraulc pumps, located low n the crcut. A water velocty of 12 knots can be obtaned when the channel area s about 10 square feet. Wndows n the channel sdes are provded for observaton. The Natonal Physcal Laboratory has reached the fnal desgn stage on a crculatng water channel wtth a test secton abou't 6 feet wde and 4 feet deep, and wth a maxmum water speed a lttle below 4 knots (9). ntal model studes were made n the Cambrdge Unversty Engneerng Laboratory under the sponsorshp of the Brtsh Shpbuldng Research Assocaton. The nsttute of Naval Archtecture at the Unversty of Genoa has a new crculatng water channel now beng calbrated, Fgure 24. n Japan, a new horzontal loop flow channel at the Techncal Research Laboratory of the Htach Shpbuldng and Engneerng company has a wndowed cross-secton 4 feet square. Calbratons are sad to show velocty fluctuatons less than per cent up to 3.5 knots; the channel s already n use studyng rudder acton n a propeller race. t s understood that the flow crculatng channel at the rebult Mtsubsh Experment Tank, Nagasak, has a measurng secton 4 feet wde by 2.6 feet deep and a water speed of 4 knots. A most unusual flow channel has recently been bult at the DeVoorst Hydraulcs Laboratory, located below sea level near Emmeloord on one of the remarkable polders of the Zuderzee works. Here lterally s a wnd tunnel over a model basn. The basn s 328 feet long, wth a wdth of 13 feet and depth of 2.5 feet. Ar flows n a closed vertcal loop at veloctes over the water surface up to 40 knots. When ths unque faclty was observed n operaton, the varaton of wave heght, length, and shape wth fetch were strkngly apparent. CAVTATON TUNNELS New varable pressure water tunnels are characterzed by greater versatlty, sze, and attenton to ar content. The functon of resorbers s to redssolve entraned ar bubbles before they return to the test secton. Followng the lead of the Hydrodynamcs Laboratory at the Calforna nsttute of Technology (25), many of the new cavtaton tunnels are ncorporatng some form of resorber. n the new water tunnel under constructon at the Natonal Physcal Laboratory (9), an exceedngly deep resorber crcut of large volume s beng ncorporated n order to provde generous pressure and tme encouragng ar to redssolve. n fact the lower horzontal leg of the tunnel crcut s 180 feet below the test secton and has a length of 87 feet. The steel tube below ground, from 10 to over 13 feet n dameter, s grouted nto concrete rngs. Pressure n the 44-nch crcular closed-throat test secton of the NFL tunnel wll be varable from near O up to 6 atmospheres absolute, and water velocty up to 30 knots drven by an 850 HP motor wth a vertcal shaft to the mpeller n the downstream vertcal leg. The workng secton wll be at the Courtesy Professor ng. Aflo U Bella Fgure 24. New ('rculatng Water Channel Nearng Completon at the Unversty of Genoa. Apparatus for graphcally recordng the model resstance appears on the centerlne of the rght leg of the channel. Courtesy Superntendent. Shp Dvson Fgure nch Water Tunnel Buldng Under Constructon at Feltham for the NPL Shp Dvson. Laboratory offces wll be n the foreground, the plant room n the back wng, and the cavtaton tunnels between them athwartshps.

18 ground level n a new water tunnel buldng, Fgure 25. Provsons are beng made at NFL for tests of 24- nch propellers n open water, usng the same sze model as planned for the new cavtaton tunnel. An auxlary carrage, to be towed by the exstng carrage over the hgh speed basn at Teddngton, has been bult to carry the large propeller dynamometer. The new 30-nch cavtaton tunnel at the Admralty Research Laboratory (3) has a 4-pass resorber. The lower left duct n the photograph, Fgure 26, supports the varable ptch propeller whose plane of rotaton s horzontal to keep t under a unform pressure head. The 850 HP drvng motor s drect connected above the propeller. Water s then mpelled down ths leg, takes two 90-degree bends then up the upper left leg, then down and up agan to the elbow ahead of the test secton. Transt tme for a bubble through the resorber at maxmum water velocty s over 70 seconds.!4lr PSD Courtesy Mr. F. S. ßrt Fgure 26. The Resorber Pt for the 30-nch Varable Pressure Water Tunnel at the Admralty Research Laboratory. The pt s 35 feet n dameter and 0 feet deep. Each pass of the tunnel s 11 feet n dameter. -Courtesy Mr. ' S Burt Fgure 27. The Completed 30-nch Water Tunnel at the Admralty Research Laboratory. The flow drecton sfrom the left n the photograph, past the 3 wndows opposte the long workng secton, and then to an easy dffuser wts a generous straght length before makng the frst 90-degree bend. 16

19 The Admralty Research Laboratory tunnel has an exceptonally long test secton, 15 feet equvalent to 6 tmes the dameter of the jet, Fgure 27. Stablty of flow, constancy of pressure, and greatly mnmzed wal effect are attaned throughout the speed range up to 36 knots by a slotted wall workng secton. Slotted walls n water tunnels are new, and the Admralty Research Laboratory was a prme developer of ths arrangement. Slots were sad to be really effectve only when the test secton s long. n ths connecton, the Sujerntendent ponted out that a workng propeller s a long body and that a long test secton s needed to treat t properly. Pressure n the test secton s adjustable from about 0.1 to 3.0 atmosphere absolute. Prncpal nstrumentaton s by stran gages wthn the models under test. The cavtaton tunnel at the very modern Shpbuldng Laboratory of the Deft Unversty of Technology (12) has a test secton 11 nches square n whch a water velocty up to 18 knots s obtaned by a 20 HP mpeller hydraulcally vared up to 700 RPM, Fgure 28. The propeller shaft s n the down- erlands Shp Mcdel Basn becomes another classc frst for that ngenous laboratory (26). The test secton s crcular, 16 nches n dameter, wth a slotted wall to reduce boundary effects, Fgure 29. Wth Courtesy Dr. W. P. A. van Lammeren Fgure 29. Frst Varable Wake Varable Pressure Water Tunnel, Developed by the Netherlands Shp Model Basn. Flow s ndvdually controlled through each of the ducts to the left n the photograph; the propeller s beng tested n a nozzle whch has been made of plastc so the flow can be observed. partly closed flow regulator, the mnmum cavtaton number s about 2, and the maxmum water velocty about 12 knots. The Pars cavtaton tunnel, Fgore 30, has a closed -Courtesy r. JeUe Gerrttsma Fgure 28. Delft Varable Pressure Water Tunnel. Developmental work for the varable wake tunnel at Wagenngen was accomplshed here. stream drecton, as n the shp, and propeller model measurements are taken up to 3000 RPM and 4.3 HP. These condtons are obtaned wth the conventonal gude vanes and honeycomb n the elbow ahead of the propeller poston. The Delf t tunnel was utlzed by the Netherlands Shp Model Basn to develop a flow regulator to smulate crcumferental as well as radal wake varatons over a propeller dsc. An alternate elbow ahead of the test secton was dvded essentally nto 146 elements, the flow through each of whch could he regulated. A rotatng rake wth 13 ptot tubes enabled a rapd velocty survey to check the desred velocty dstrbutofl. Another development at Deft s a new test secton, about 6 nches wde, n whch a 2-dmensonal propeller profle can be moved transversely to smulate a propeller blade n crcumferentally varyng wake. The varable wake cavtaton tunnel at the Neth- Courtesy of the Drector Fgure 30. Lower Loop of Cavtaton Tunnel at the Pars Model Basn. The bellows flter vbratons that may arse from the mpeller drven by the large motor n the foreground. 17

20 Courtesy Professor J. K. Lunde Fgure 31. Norwegan Tunnel Model at Trondhdm. n ths arrangement, flow condtons are beng studed n an exceptonally short dffuser secton to the rght of the flexglass test secton. --Cocu ey Chef Engneer Ler,r,art Pehrsson Fgure 33. Cavtaton Tunnel at the Karlstads Mekanska Werkstad n Sweden. Control panel and measurng devces are n the foreground. Courtesy Dr. -1ns Edstrnd Fgure 32. Swedsh Cavtaton Tunnel Recently Completed at Göteborg. throat of clear plastc about 36 nches n dameter. A water velocty of 30 knots s attaned n the test secton of ths tunnel. The Admralty Experment Works has erected and housed a very large cavtaton tunnel (4). n Norway at the Trondhem Shp Model Tank. experments are underway on a small tunnel to gan experence for a proposed large cavtaton tunnel. The present faclty, Fgure 31, has a basc 8-nch dameter closed jet workng secton wth a water speed of 20 knots, and two alternate slotted wall arrangements wth maxmum test speeds of 10 and 24 knots respectvely. The Swedsh State Shpbuldng Expermental Tank at Gothenburg has recently added to ts excellent facltes (27) a new varable pressure water tunnel, Fgure 32. The Krstnehamn tunnel of KMW, Fgure 33. contnues ts outstandng propeller research. The Escher Wyss laboratores n Swtzerland have long been a leader n hydrodynamc research. There, over 30 years ago, ar was used as a more convenent flud for studyng hydraulc models, a practce now wdely appled n shp model research. The laboratores support hgh qualty desgn and producton of dverse naval machnery ncludng controllable ptch propellers, hydraulc pumps, gas turbnes, and n tme perhaps gas cooled reactors. To permt cavtaton observatons at hgher Reynolds numbers, a large varable pressure water tunnel was added n 1956 to the laboratory facltes of Escher Wyss (28). A sngle console, Fgure 34, Contans all operatng and measurng controls, ncludng the eyepeces for two optcal systems for remote observaton of cavtaton from two drectons. The 459 HP dynamometer on top of the test secton has hydraulc transmsson to the control console where the torque s weght-balanced. Two 400 HP drvng pumps, Fgure 35, wll delver aganst a pressure head of over 300 feet; however, the heavy test secton wthstands the statc pressures so that the spral casng of the model can be of lght constructon. At the tme of vst to Etcher Wyss, a model turbne runner test frst showed strkng cavtaton swrls along von Karman vortex streets, and then was carred up to runaway cavtaton condtons. The Spansh cavtaton tunnel at El Pardo s ecentally the same desgn as the large tunnel at the Netherl3nds Shp Mcdel Basn, together wth a number of d:tal desgn alteratons learned by ccn- 18

21 Courtesy Escher Wyss Ltd Fgure 34. New Cavtaton Tunnel at the Escher Wyss Laboratores. From the pressure sphere, water flows to the left, through the hydraulc turbne model under test, to the tal water cylnder. sderable operatng experence at Wagenngen. The El Pardo tunnel, erected n 1951, has a test secton 36 nches square wth rounded corners and an mpeller motor of 300 HP. The Kng's College tunnel was made from parts of a flow faclty bult orgnally n Germany for acoustc tests on underwater weapons (29). ts welldesgned converson to a cavtaton tunnel provded the largest tool avalable for propeller research and t has been exceptonally well used. The 12-foot long test secton for ths tunnet, followng a 5 to contracton, s 40 nches hgh and 32 nches wde wth rounded corners. n Yugoslava. a new cavtaton tunnel, wth a test secton about 40 nches square, s currently beng erected at the Zagreb Shpbuldng Research nsttute. nterchangeable test sectons wll be provded. Vospers Lmted n Great Brtan, long a leader n the development of hgh-speed small craft, s understood to have bult recently a cavtaton tunnel wth a 20-nch square test secton. Ths frm wll no doubt make creatve use of ths faclty n experments on hgh speed propellers, wth both axal and angular nflow, and n research on rudders and stablzng flns. Courtesy Escher Wyss Ltd. Fgure 35. Escher Wyss Cavtaton Tunnel. From the tal cylnder, water s valved to two radal pumps connected ether n seres or parallel, thence to the bottom pressure sphere, and va a ventur to the top pressure sphere. Flow drecton can be reversed for models operated as pumps. 19

22 -Offcal U. S. Navy Fgure nch Varable Pressure Water Tunnel Under Constructon at Carderock. The resorber pt s 70 feet deep n bed rock lned wth stanless clad steel. Courtesy of the Drector Fgure 36. Largest Water Tunnel n the Unted States, Located at the Ordnance Research Laboratory, Pennsylvana State College. At the Ordnance Research Laboratory located at Pennsylvana State College, a large tunnel was completed n 1950 for the purpose of testng complete selfpropelled models of underwater bodes under controlled condtons (30). n the 48-nch dameter workng secton 14 feet long, water speed can be contnuously vared to selected veloctes up to 48 knots, Fgure 36. The 95-nch, 4-bladed, adjustable ptch mpeller s drven by a 2000 HP varable speed nducton motor. The 36-nch varable pressure water tunnel now under constructon at the Davd Taylor Model Basn (31) wll have a vertcal double-pass resorber wth an outer cylnder 25 feet n dameter extendng 70 feet below the ground elevaton. t s estmated that bubbles enterng the resorber wth dameters of nch or less wll be reabsorbed nto soluton. Desgn of the new DTMB cavtaton tunnel was materally asssted by tests of a 6-rcale plot model at the St. Anthony Falls Hydraulc Laboratory of the Unversty of Mnnesota. n the full scale verson, a 2880 HP pump wll produce a maxmum water speed of 50 knots n the test secton. The absolute pressure on models under test wll be varable from 2 to 60 pounds per square nch. Both an open jet and a closed jet test secton are beng constucled. Removable propeller shafts from both upstream and downstream drectons wll provde flexblty, together wth ndependent dynamometer drves for counterrotatng propellers. t s expected that the DTMB tunnel, Fgure 37, wll be completed by md AcKNoWLEDGMENT The gracous readness of the varous towng tank superntendents to furnsh the photographs presented n ths paper s gratefully acknowledged. Apologes are made for falure to menton ans' new facltes unknown to the author, and for any unntended emphass dsproportonate to the mportance of the facltes brefly descrbed. Apprecaton s expressed to the Bureau of Shps for sponsorng partcpaton n nternatonal tankery by the U. S. Navy of ultmate beneft to all martme natons. 20

23 REFERENCES "Hydrodynamcs n Shp Desgn," by H. E. Saunders, Socety of Naval Archtects and Marne Engneers, Revewed n the Nov ssue of the JOURNAL. "Study of Turnng Tests At The Pars Model Basn," by J. Bleuzen, Conventon of the Assocaton Technque Martme et Aeronautque, June 1946, DTMB Translaton 222. "The Rotatng-Beam Channel and 30-nch Water Tunnel at Admralty Research Laboratory," by E. H. Lever, H. Rtter, M. Woolfson and C, T. Wrght, nsttuton of Mechancal Engneers, November 'The Admralty Experment Works, Haslar," by R. W. L. G wn, Transactons of the nsttuton of Naval Archtects, 'A Rotatng Arm and Maneuverng Basn," by W. F. Brownell, Proceedngs of the Amercan Towng Tank Conference, Septembar Proceedngs of the Symposum on The Behavor of Shps n a Seaway, Netherlands Shp Model Basn, September The Seakeepng Laboratory of the Netherlands Shp Model Basn," by W. P. A. van Lammeren and G. Vossers, nternatonal S pbnldng Progress, January "New Equpment for Model Tests At All Headngs To Waves," by E. V. Lews. Expermental Towng Tank, Stevens nsttute of Technology, Memorandum 110, June "Natonal Physcal Laboratory New Shp Hydrodynamcs Laboratory," by J. F. Allan, Transactons of the nsttuton of Naval Archtects, Proceedngs of the Eghth nternatonal Towng Tank Conference, Madrd. September "The Pars Model Basn," La Revue Martme, September "Descrpton of the New Laboratores of the Department of Naval Archtects, Unversty of Technology, Deft, Holland; Part 2. The Shpbuldng Laboratory," by J. Gerrtsma, nternatonal Shpbuldng Progress. February "The New Towng Tank," by W. A. Crago, Saunders-Roe Lmted. "Bref Dasc'pton of the Model Testng Basn, Ottawa, Canada," by E. S. Turner, Laboratory Memorandum MTB, 'Shp Model Towng Tank At M..T.," by M. A. Abkowtz and J. R. Paullng, Transactons of the Socety of Naval Archtects and Marne Engneers, May "The Unclergraduate Educaton of Naval Engneers-U. S. Naval Academy," by R. B. Madden, JOURNAL OF THE AMERCAN SOCETY OF NAVAL ENGNEERS, February 'Of Seas and Shps and Towng Tanks," by R. A. Fuchs, Calforna Monthly, January "The Convar Towng Tank-Frst Year Problems," by F. L. Thornburg, Transactons of the Socety of Naval Archtects and Marne Engneers, 1957, "Report On the Actvtes of the Turksh Shpbuldng Research nsttute and Present State of the Model Expermental Tank," by Ata Nutku, stanbul, "Ma'nc Engneerng Notes From the Sovet Press," by B M. Kassell, JOURNAL OF THE AMERCAN SOCETY OF NAVAL ENG- NEERS, May 'Expermental Shp Model Testng Tanks," by Aldo Andreon, nternatonal Shpbuldng Progress, March "Expermental Tank," Mtsubsh Shpbuldng and Engneerng Co., Ltd. "Kngs' College Towng Tank," Shpbuldng and Shppng Record. June 'Hstory of the Netherlands Shp Model Basn Durng the Frst 25 Years," by W. P. A. van Lammeren. "Ar Resorpton n Water Tunnels." by F. B. Brown, Calforna nsttute of Technology Report N-62, March "Testng Screw Propellers n A Cavtaton Tunnel wth Controllable Velocty Dstrbuton Over the Screw Dsc," by W. P. A. van Lammeren, New England Secton, Socety of Naval Archtects and Marne Engneers, Aprl "Statens Skeppsprovnngaanstalt, Goteberg," by H. F. Nordstrom, Publcaton No. 32, "New Testng Plant for Measurng Characterstcs and Observng Cavtaton Phenomena n Water Tu.rbnes and Pumps," by J. Osterwalder and W. Lecher, Escher Wyss News, Number 2, "Propeller Cavtaton: Some Observatons From 16 nch Propeller Tests n the New Kngs' College Cavtaton Tunnel," by L. C. Burll and A. Emerson, Transactons of the Northeast Coast nsttuton of Engneers and Shpbulders, "Garfeld Thomas Water Tunnel Operatons," by J. M. Robertson, Ordnance Research Laboratory, May "A 36-nch Varable Pressure Water Tunnel," by W. F. Brownell, DTMB Report 1052, June 1956.

24 NTAL DSTRBUTON Copes 8 COBUSHPS, Lbrary (Code 312) 5 Tech Lbrary Tech Asst to Chef (Code 106) Res & Dea Program Plan (Code 320) Sc Res (Code 442) 2 CHONR, Mech Br (Code 438) 1 OR, JSNRL 1 COR, USNOL CUR. USNOTS, Pasadena, Calf. CO & DR, USNUSL, New London, Coon. CO & DR, JSNEL, San Dego, Calf. CO & DR, USBTL, Phladelpha, Pa. CO, USNUOS, Newport, R.. OR, JSNEES, Annapols, Md. CO & DR, USN1DL, San Francsco, Calf CO, USNMDL, Panarra Cty, Fa, 1 DR, US Mall Lab, Brooklyn, N. Y. OR, Towng Tank, Convar Do of Gereral Dynamcs Cnrp, San Dego, Calf. DR, Exper Bava Tank, Unv of Mch, Ann Arbor, Mch. DR, anfetd Thomas Water Tunnel, ORL, Unversty Park, Pa. 1 Head, Dept of NAME, MT, Cambrdge, Ma SS. t DR, Hydraulc Lab, NNSB&DDCo., Newport News, Va. DR, Shp Model Towng Tank, 'lt, Cambrdge, M4ss. DR, [T, ST, Hoboken, N. J. DR, Towng Tank, U. S. Nan Academy, Annapols, Md. DR, Hydraulc Model Basn, Uno at Calf., Rchmond, Calf. DR, Robnson Model Basn, Webb nst of Tech, Glen Cove, L.., N. Y. 0mO, Postgrad School, Webb nst of Tech, Glen Osee, L.., N, Y. Chef, Nat Hydr Lab, US Ball BuStand 1 Hydra Lab, CT. Pasadena, Calf. DR, Flud Mech Lab, Unv of Calf. Berkeley, Calf. 0fR, Hydr Lab, Carnege nst of Tech, Pttsburgh, Pa. DR, Hydr Lab, Colo. St Une, t. Collns, Cols. De, owa nst of Hydn Res, owa Cty, la. Copes DR, S Anthony Falls Hydr Lab.. Unv el Mno., Mnneapols, Mno. Dr. L. Kretschmer, Schffbautechnsche Versuchsanstalt, Venna XX, Austra Or. A. Andrenn, Tech Res sst, [oper Tank, San Paulo, Brazl 1 DR, Model TestnZ Basn, Nat Res Councl, (lftowa, Canada t t Prat. C. W. Prohaska, Dansh Model Basn, Hortekaer, Denmark Hydno Dv, An L, Teddngton, England Mr. W, P. Balker, D, Wm. Denny & Oros, Ltd. Dumbartor, Scotland Or. F. H. Todd, Supt of Shp Dv, NPL, Teddngton, England tr. P. P.. Crewe, Chef Engr. Saunders-Roe, Ltd sle nf Wght, England Prof. L. C. Burrll, Prof. of Nao Arch., Unv nf Durhan, Kngs College, Newcastle-on-Tyne 1, England Supt, Shp Model [oper Tank, Vcbers-Armslrong Ltd., St. Albans, Herts, England 9 USN Afach, London, England RAD Roger E. kf. Brard, Dr, Bassn d'essas, des Carenes, Pars, Fnance Prof. J. J. Rahola, 0mnland loaf of Tech, Helsnk, Fnland Dr. H. W. E. Lerbs, Dr, Hamburg Model Basn, Homburg, Germany 1 DR, Versuchsanstalt fr Wasserbau und Schffbau, Berln 87. Germany 1 Prof. Dr. ng. Alla d Bella, Dr, nst of Nao Arch, Unv of Genoa, Genoa, taly 1 Pres. ng. l. Puglese, nsttuto Naz. ner Stud ed [sp. d Arch. Nay., Rome, taly Prat. D. Volker, ndan nst of Tech, Kharagoun, West Bengal, nda Chef, Meguro Model Basn, Transportaton Tech Res nst Tokyo, Japan DR, Enper Tank, Mtsubsh Shpbuldng & Engn Co., Lfd Nagasak, Japan Mr. Tatoua to, Mnstry of Transportaton, Shpbuldng Secton, Tokyo, Japan Prnf. W. P. A. van Lammeneo, Netherlands Shp Model Basn, Wagenngen. Netherlands DR, DeVoorst Flydr Lab, Emmeloord, Netherlands Dr. J. Gerrtsmv, msmo of Tecr, Shpbemldng Lab., Delft, Netherlands Copes Prof: J. K. Lande, Dr, Stafeon Skpomodelltaokeo, Truodtemv, Norway DR, Kryloff Shpbuldng Bes lost, Lenngrad, Russa DR, AEW, Haslar, England Dr. J. F. C. Conn, Pnot. st Nao Arch,Unv st Glasgow Glasgow W-2, Scotland Mr. J. M. Fergssnn, Supt of [oper Task. John Brown & Co. Ltd., Glastow. Scotland 1 Dr. Manuel Lopez Acevedo, Casal de Experencas Hdnodmoascas,.ladrd, Span Mr. L. Pehrsson, Chef of Cavtaton Tunnel, Korlstads tek. Werk, Krstnehamn, Sweden Prof. E. G. E. Hogner, moyal nst of Tech, Stockholmm, Sweden Dr.. Ertstrurd, Slatens Skeppsprovnngnanstalt, Cotebnnk C, Sweden Chef, Hydro Res, Escher Wyss Lab, Zurch, Swtzerland DR, stanbul Model [ope, Took, Turksh Shpbuldng & Res nst. stanbul, Turkey Prof. S. Slovc, Shpbuldng Res lest, Zagreb, Yugoslava Dr. E. V. Teller, Skpsbyggrg, Norges Teknnke rtogsknle, Trondhern, Norway NAVY.DPPO PNO. WASH.. D.C. 23