THE UNIVERSITY OF MICHIGAN COLLEGE OF ENGINEERING Department of Naval Architecture and Marine Engineering Final Report RESISTANCE AND PROPULSION TESTS ON TWO SERIES 60 MODELS Finn C. Michelsen R. B. Couch Hun Chol Kim ORA Project 03509 under contract with: DEPARTMENT OF COMMERCE MARITIME ADMINISTRATION CONTRACT NO. MA-2084 WASHINGTON, D.C. administered through' OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR April 1961

I. INTRODUCTION This report presents the result of resistance and self-propulsion tests of two Series 60 parent models carried out at the Ship Model Towing Tank of The University of Michigan from March to August, 1960, and November, 1960. The parent models pertaining to these tests are David Taylor Model Basin (DTMB) Series 60 Model Nos. 4210 (0.60 block coefficient) and 4213 (0.75 block coefficient). Corresponding numbers of the Michigan models are Nos. 912 and 913, respectively. The original DIMB parent models were 20 feet (LBP) long compared to the 14-foot models used at Michigan. DTBM data were to be used as the basis for comparison. Thus the purposes of the tests may be summed up as follows: 1. Development of techniques and instrumentation for propulsion and propeller tests at The University of Michigan Tank. 2. Correlation of data from the Michigan Tank with those of DTMBo It may be pointed out that self-propulsion tests have not previously been conducted at Michigan. For these purposes, the U.S. Maritime Administration has sponsored the project under U.S. MARAD Contract No. MA-2084, ORA Project 03509. 1

II. SUMMARY Results of the resistance tests are summarized in Figs. 1-4. Those of the open-water and self-propulsion tests follow in Figs. 5-8. Calculation of self-propulsion data are given in Tables 3-6 in the appendix. The figures are self-explanatory. Methods of data reduction are identical to the standard method used at DTMB. The 1947 ATTC friction formulation is used throughout. The resistance data agree within 5% of Cr for Model No. 912 (0.60 block) and within 10% for Model No. 913 (0.75 block). Better agreement is achieved with the finer model, but all data show a reasonably good correlation. Correlation of open-water propeller data show better agreement for UM Prop. No. 2 (used with UM Model No. 913). The first propeller, UM Prop. No. 1, was found to have 6.7% higher pitch than the parent's. This would ace count for some of the deviation in the test data forProp. No. 1. Self-propulsion test data indicate a good agreement in shaft horsepower. The higher pitch of propeller No. 1 accounts for the deviation in rpm in Model 912. Wake frictions and thrust deduction fractions are generally higher than shown by DTMB data. Wall-effect corrections made in both- EP and SHP tests were based on a tentative, unpublished formflila developed in the National Physical Laboratory in England. For turbulence stimulators, a 0.036-in.-diameter trip wire placed at 5% LBP from the fore perpendicular was used. For Model 913, an additional trip wire placed at the quarter point of the stern was used. This is believed to stabilize the separation point. Although it seems to be effective, in the light of slightly higher Cr values found in Model No. 913 compared to those of DTMB, it will have to be more fully explored. In summing up, the correlation of data from the Michigan Tank with those of DTMB is believed to be good. The technique of conducting these tests has been worked out, and with a new carriage and more test data better correlation should be obtainable. 5

III. MODELS, EQUIPMENT, AND TEST PROCEDURES A. MODELS AND THEIR SELECTION Model sizes were chosen so that the propeller size would not be less than six inches in diameter to avoid appreciable scale effect and that the model would not be so large that appreciable restricted channel effects were present. Both models were,built to a size of 14 feet LBPo The propellers selected were the intermediate sizes of the three tested by DTMB on each of their models, DTMB Prop. No. 3378 and No. 3379 for 0,60 block and 0.75 block models, respectively. The Michigan Prop. No. 1 for 0.60 block model is 6.272 in. in diameter, and Prop. No. 2 for 0.75 block model, 6.969 in. in diamter. The ship models were constructed of lifts of sugar pine in much the same manner as is done with wood models at DTMB. They were painted with several coats of gray enamel and varnished. The models were fitted with shoepiece and rudder (and a dummy hub for resistance tests) made geometrically similar to the DTMB modelso Location of propellers with respect to bossing was controlled by reading the thrust gage within a given range while running-a necessary procedure because the thrust gage is directly connected to the propeller in such a way that the propeller has about 3/8 in, of "play" in a fore and aft direction over the full range of the gage. Rudder angles were zero for all tests, All tests were run at design displacements. Model and propeller data are given in the appendix, Tables 1 and 2. Bo EQUIPMENT For resistance tests the old spring dynamometer was used to some extent. In most cases, however, and for all self-propulsion tests the towing force was measured with an electronic dynamometer developed at this tanko In addition to being more accurate, the electronic dynamometer indicates force directly in pounds, and makes it possible to obtain several sets of data points during one run in the tanko Self-propulsion data were obtained from simultaneous readings of all instruments, and not from average values. A brief description of the instrumentation is as follows. Towing Carriage. oElectric-powered with Ward Leonard control system, 25-hp motor, maximum speed about 7.5 knots. (To be replaced with a new carriage with a maximum speed of about 20 ft/sec and equipped with electronic speed control in 1961 ) Resistance Dynamometer o-The new electronic resistance dynamometer built at The University of Michigan consists of a transducer and displacement indi5

cator connected to an x-y plottero It was used both for resistance tests and for the propulsion tests. This dynamometer is designed so that any part of total resistance can be counterbalanced by means of weights. Propulsion Dynamometer.-Standard 1/8-hp Kempf and Remmers J-05 mechanical propulsion dynamometer utilizing a 220-volt d-c drive. The tachometer was altered from the original mechanical to a photoelectric type using a digital counter for revolution display. Carriage Speed Indicator.- A new rotopulser driven from the motor shaft with an electronic digital display unit was used to indicate carriage speed, With proper settings of constants on the instrument panel, carriage speed may be directly read in ft/sec, mph, knots, etc. Figure 10 shows the equipment arrangement for self-propulsion tests. The equipment list, corresponding to the numbers indicated on Fig. 10, is as follows: 1o Autograf - Two-axis recorder, Model No. 3, Series 78, Fo L. Mosely Co., Pasadena, California. 2. Displacement Indicator - Model 300, Daytronic Corp., Dayton, Ohio. 3. Force Transducer - Model 140-10 (with magnetic shield), Daytronic Corp. 4. R-C Filter - 0-10,000 MFD in steps of 1,000 MFD, 15 max volts. 5. Rheostat Control. 6. Tachometer Head - Model 506 A, Series 003-01393, Hewlett Packard Co. 7. Propeller Dynamometer - Kempf and Remmers J-05. 8. Electronic Counter, Model 523B, Series 675, Hewlett Packard Co. 9. Dynamometer Frequency Counter - 610, Series No. 101, Dynapar Corp., Chicago, Illinois 10o Rotopulser - Dynapar, 1200 pulses per revolution. Propeller Boat, —oFor openswater propeller tests, a stainless-steel boat was built. Both dynamometers, Kempf and Remmers J-05 and J-04, fit into this boato Open-Water Dynamometer. -Both propellers were first tested with the 1/86

hp Kempf and Remmers J-05 dynamometer. A new 1-hp Kempf and Remmers J-04 was later used for retests at higher Reynolds numbers and and low values of speed of advance. Propeller dynamometers are shown in Figs. 12 and 13. Installations of dynamometers in the model and propeller boat are shown in Figs. 14 and 15. C. TEST PROCEDURES Prior to each self-propulsion test, a Df correction chart was prepared from the results of previous resistance tests. Resistance increase due to the wall effects was estimated and added to the amount of viscous correction of Df to bring the model propeller loading equivalent to the ship point of propulsion. Although the present carriage speed control at the Michigan Tank does not permit an easy preselection of speed and hence an exact amount of Df, the values of Df have been matched by duplicating the same spot more than once at a constant carriage speed setting. As the instrumentation was set up, resistance was directly read in pounds; speed in ft/sec; revolutions in milli-seconds per revolution; and thrust and torque in grams and gram-centimeters, respectively. Other than these, all the procedures are identical to the method described in W. T. Potter's ":A Manual for the Calculation of Propulsion Tests at the DTMB."2 Open-water propeller tests were run essentially at constant carriage speed and varying rpm, to cover the required range of propeller speed of advance. With the 1/8-hp propulsion dynamometer, due to the small power, it was hot possible to obtain low J-values even at reduced carriage speeds, With the 1-hp motor of the.J-04 dynamometer, however, it is possible to obtain a full range of J-values at maximum carriage speed, thus maintaining the highest possible Reynolds number with the present equipment. Reynolds numbers were in the range of 2.5 x 105 to 3.2 x 105. Dfo values (measured amount of viscous correction to propeller loading) have been.matched to Df values (theoretically exact amount of correction) within about + 4~ on the.average and to a + 12% mnaximum. 2DTMB, October, 1954, 2nd ed. 7

IV. DISCUSSION OF RESULTS The result of the resistance test of 0.60 block Model No. 912 correlates excellently with DTMB results, but that of the 0.75 block Model No, 913 has slightly more scatter and differs about 10% in Cr, the Michigan data being slightly higher in general. This seems to result from instability of turbulent flows on fuller models, inadequate wall-effect correction, and/or inadequacy of the flat-plate friction extrapolator. Although a very small difference is involved, Michigan data are a shade lower from speed-length ratio 0.89 to 0.96 for Model 912, and from 0.78 to 0.82 for Model 9130 At the high-speed end, Michigan data tend to become appreciably higher. A similar observation is noted for the SHP data at almost the same speeds. It is believed that this condition is partially due to blockage effect correction. As for the results of the self-propulsion test, SHP and EHP/SHP agree well with DTMB data. For Model 912, rpm is about 3% lower throughout. This is mainly due to the 6o7% higher propeller pitch than that of the DTMB propeller. Thrust deduction in general shows appreciably higher values than those of DTMB contrary to expectations. No explanations of this fact has been attempted at this time. Wake values, however, are as expected in view of the smaller model size.3 BLOCKAGE EFFECT It was estimated that the maximum increase in total resistance due to blockage would. be about 2-3% at about 10% above the trial speed for 14-foot models. Previously, in a similar comparative study on a Series 60 model, a 12-1/2-foot model had been tested. This model had a blockage ratio (model cross-sectional area over the tank cross-sectional area) of about 1/2 of 1% and had shown no blockage effect as far as could be determined within the accuracy of measurements. The present models had blockage ratios of 0.74 of 1% for Model 912 and 0.81 of 1% for Model 913 with an estimated effective tank cross-sectional area of 190 square feet. Rather than accept the conse= quences of having possible laminar flow on propellers of diameters smaller than 6 inches, a 14ifoot model size was chosen. A number of empirical and theoretical studies have been made in regard to blockage effect. Some of these are mostly concerned with either extremely shallow draft or high speed. Corrections applied to Model 912 and Model 913 3Van Lammerren, Troost, and Koening, Resistance, Propulsion and Steering of Ships, Technical Publishing Company, Holland, 1948, p. 150. 9

by such methods would be nil. After consideration an estimate was finally based on the semi-emipirical formula developed at the National Physical Laboratory in England. The formula is as follows: Resistance increased in % = nT 1V3/ A = Cross-sectional area of the tank in sq fto V = Volume of the model in cubic feet. nT = Logarithmic index of the change in total resistance with respect to speed. in tne absence of a better estimate, this formula has been used throughout the present analysis' It is planned, however, to study blockage effects in the Michigan tank. The University of Michigan Ship Model Towing Tank has approximately a 22foot width and 10-foot depth, but the section is semi-circular at the bottom. At about 140 feet down the length of the tank, there is a false bottom about 7 feet below the water level. It covers only about 4/5 of the 22-foot width, Figure 11 is a sketch of the tank. The cross-sectional area, therefore, can be taken as anywhere from 160 to about 210 square feet. At present, 190 square feet has been used as an estimate. The effect of the false bottom is unknown and will indeed be difficult to ascertain. The best solution will be to have it removed. The total resistance increase based on the given equation is shown in percent of total resistance in Fig. 9. This correction has been applied in both the resistance and self-propulsion test analysis. TURBULENCE STIMULATOR Based on the experience obtained from the 12-1/2-foot model tested, a trip wire stimulator was used exclusively. For the 12-1/2-foot model, both studs and trip wires were tried, and the trip wire was found to be the most satisfactory. The trip wire stimulator was of 0o036-in.-diameter copper wire placed at 5% LBP from the FP secured to the model by 0O 036-in diameter bent nails about 1-1/2 in. aparto Model 913 was initially run with a trip wire stimulator on the bow (as was done with Model 912), and then with an additional trip wire placed at the quarter point of the stern. This was based on the belief that the separation From the confidential correspondence between Dr. Hughes and Professor Coucho 10

point of the boundary layer will be stabilized due to the second stimulatoro The test seems to confirm this, although the problem will have to be more fully explored. The drag of an additional stimulator in the stern seemed to be negligible. Water spray was used on the return after high-speed runs. This possibly helpsturbulence stimulation, but the major purpose is to clam down waves generated in the tank, and the practice was followed only when needed. A high-speed practice run at the beginning of a sequence of tests is always made to insure that the water in the basin is moderately stirred. When this precaution is not followed, it has been noticed that the first couple of runs invariably produce lower resistance data. FRICTION EXTRAPOLATORS Throughout the test, the 1947 ATTC friction extrapolator was used exclusively. It was found from the 12-1/2-foot-model tests that the 1947 ATTC friction extrapolator resulted in closer agreement between Michigan and DTMB data than could be obtained by using the 1957 ITTC friction extrapolator. 11

ACKNOWLEDGMENT The authors are grateful to the members of The University of Michigan staff who participated in the conduct of the test program. In particular, the cooperation of Mr. Albert F. Harloff is greately appreciated. 12

APPENDIX

LEGEND: _: Corresponding / DTMB results / o: U of M 912 data I points corrected for wall effects / I Water temperature 67~F 7 / 6 I' I I I 1 / vi i I w / z._4 4 (I, C, w 4 / 0 o3: II... 2 3 4 - SP EED-LENGTH RATIO 4.5.6.7.8.9 1.0.........., _ _ _ _ MODEL SPEED, FT. PER SEC. Fig. 1. Total resistance vs. model speed, series 60,.60 block, U of M 912 14-ft model, DTMB 4210 20-ft model with rudder.

U of M 912 14-ft model 2.4 DTMB 4210 20-ft model with rudder 2* | - - -: DTMB results with rudder 2.0. U of M 912 results corrected for wall effect 1.8 1 1.4 1.2 1.0 0.8 0.6.40 ~ 50. 0.70.80.90 1.00 1.10 Speed-length Ratio, V//c Fig. 2. Cr vs. speed-length ratio, series 60,.60 block.

LEGEND: -- - —: Corresponding / DTMB results ~: U of M 913 data points corrected for wall effects / Water temperature 73~F -i 7 _ 6 / 5 )_2_3_ 456__ I i w -3 /,^ SPEED- LENGTH RATIO 21.3.4.5.6.7.8 20 23A456 MODEL SPEED, FT. PER SEC. Fig. 3. Total resistance vs. model speed, series 60,.75 block, U of M 913 14-ft model, DTMB 4213 20-ft model with rudder.

3.8 U of M 913 14-ft model 3.6 DTMB 4213 20-ft model with rudder / 3.4 - - -: DTMB results with rudder 3.2:; U of M 913 results corrected for wall effect 3.0 2.8 o 2.0 1.8 1.6 1.4 1_.2 0.8 0.3 0.4 0.5 0.4 0.7 0.8 0.9 Speed-length Ratio, V/ /L Fig. 4. Cr vs. speed-length ratio, series 60,.75 block.

DIAMETER = 6.272 in. MWR 0.261 NO, OF BLADES = 4 PITCH (.7R)= 7.195 in. BTF = 0.045 RAKE = 6,00~ P/D = 1.147 EA/DA = 0.550.. —-.APPROXIMATE CHARACTERISTICS B-4-55 PROPELLER Ho/D:1.147.8.7 l~~~ z /.6,.3/. IOKQ KT.1I J2v/nd Fig. 5. Propeller open-water test result, U of M prop. No. 1.

DIAMETER =6.969 in. MWR = 0.225 NO. OF BLADES = 4 PITCH (.7R) = 7.250 in. BTF = 0.045 RAKE.00 P/D =1.040 in. EA/DA = 0.475 --- DTMB PROPELLER NO. 3379.8 ReR 2.86x10.1... -_N 1) \^ J - v/nd Fig. 6. Propeller open-water test result, U of M prop. No. 2. ^~~~~~~~.. Fig. 6.?rope'l'ler open-wa-ter -bes-t resu'lt, U of Mv prop. No, 2,

40o 35 0.80o ~P 30 ~ ~ ~~~~ ~ 0-70 - LEGEND: A -. - -:; DTMB results 25' ~: U of M data points and results 0 G I) o 20 rd~/ 13 14 16 18 20 22 24 Speed in Knots Fig. 7-A. Self-propulsion test results for 600-ft ship. 0.60 block model 912, prop. No. 1 (parent DTMB model 4210, prop. DTMB 3378).

LEGEND: 120: DTB results / 1 ~: U of M data points 110 and results IIIII,__StS 1 100 ~ ~ ~ ~ ~ ~. ___~ ~ 90 s-'-.70 ~~~.8o W 6o e 701 20' 30 20 30 ~~.20.......L.... ~~~~~20.20, _ ~.10 14 16 18 20 22 24 Speed in Knots Fig. 7-B. Self-propulsion test results for 600-ft ship. 0.60 block model 912, prop. No. 1 (parent DTMB model 4210, prop. DTMB 3378).

.8o 50 _ _ _ _ _ _ ____II'c __-._.70...... ____ ____ ____ ____ ____ /.60 LEGEND | —: DTMB results > I,.: U of M data points, PA and results 0 ~20 0 10 05 ______ ______ 0/ 10 12 14 1 18 20 Speed in Knots Fig. 8-A. Self-propulsion test results for 600-ft ship. 0.75 block model 913, prop. No. 2 (parent DTMB model 4213, prop. DTMB 3379).

I~ ~~1 ~ 1 1 ~1-1. - 110 LEGEND: _______ 100 - —: DTMB results / 90 | O: U of M data points and results a// m,___/ t X80 70' --- 40 7_ — _-_ _ _-'_".__ _____ _ ______ 50.-400^..20 ~.2 6o........ ~ ~.o 10 12 14 16 18 20 Fig. 8-B. Self-propulsion test results for 600-ft ship. 0.75 block model 913, prop. No. 2 (parent DTMB model 4213, prop. DTMB 3379).

o 3.0 c* 2.5 A' 0 r-y c 2.0 0 H 1 5 ____ Model 913 ___/ \ ______ P o I 0I I~.~ ~ ~ 1 2 3. 0.5__________ 0 1.2 6 7 Model Speed, ft/sec Fig. 9. Estimated blockage effects.

pLOTTER. R.P. PROPELLER R- OAMO- m. ~W COUNJTIR MlTLR. 2 2 C.OP.JT.OL. b,, oaro "'rU I ~i Di~ A'r PHOT~T UAO Jarr. ION DI C AAM R PSovpELL Ilro e I 3 _ Fig. 10. Err., r.. -po.p.ulsion.tes Numbers refer to the Equipmt Lit.,14 *o.; NAo Uf - 3 i $. U~ RE5lST. DYIAMoI',~;;TE. PROPELL1ERT DYNAM OMETS | C464ZIVA-l |P| SPEEC Fig. 10. Equipment arrangement for self-propulsion test. Numbers refer to the Equipment List.

.^f II~ ~Water Level ~ \~~~~~~~~~~~~* ~'. a., 4'. ALr 24" l 0'Fig. 11. Cross section of U of M tank O' & t0" 7 ".....~ Fig. 11. Cross section of U of M tank.

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TABLE 1 MODEL DATA Model No. 912 (Parent DTMB Model No. 4210) Model No. 913 (Parent DTMB Model No. 4213) Ship Series 60 0.60 Block Ship Series 60 0.75 Block Ship Owner MARAD ORA No. 03509 Material: Wood Ship Owner MARAD ORA No. 03509 Material: Wood Model: X = 42.8571 (600 ft) Ship (600 ft) Model: 4 = 42.8571 (600 ft) Ship (600 ft) LOA L)A LWL 14.2345 ft; 170.814 in. 610.050 ft LWL 14.2345 ft; 170.814 in. 610.050 ft LBP 14.0000 ft; 168.000 in. 600.000 ft LBP 14.0000 ft; 168.000 in. 600.000 ft B 1.8666 ft; 22.3986 in. 80.000 ft B 2.074 ft; 24.888 in. 88.886 ft H mean 0.7466 ft; 8.9586 in. 32.000 ft H mean 0.8295 ft; 9.954 in. 35.55 ft fwd 0.7466 ft; 8.9586 in. 32.000 ft fwd 0.8295 ft; 9.954 in. 35.55 ft aft 0.7466 ft; 8.9586 in. 32.000 ft aft 0.8295 ft; 9.954 in. 35.55- ft A = 728.8 lb at LWL Draft, 73~F 26,349 tons, STD S.W. A = 1124.9 lb at LWL Draft, 73~F 40,644 tons, STD S.W. W.S. bare 33.4181 sq ft 61,380 sq ft W.S. bare 41.934 sq ft 77,022 sq ft rudder 0.3136 sq ft rudder 9.346 sq ft 635 sq ft appendage appendage Total 33.7316 sq ft 61,956 sq ft Total 42.280 sq ft 77,657 sq ft Ax, LWL 1.362 sq ft Friction Basis: 1947 ATTC Ax, LWL 1.703 sq ft Friction Basis: 1947 ATTC Ax, LWL 18.449 sq ft ACf... 0.0004 Ax, LWL 24.013 sq ft ACf... 0.0004 Ax, Tank Area 0.74%* Ax, Tank Area 0.81% Designed Speed 5.70 ft/sec V/,/E =.894; 22.08 KTS Designed Speed 3.76 ft/sec V//i =.595; 14.70 KTS Trial Speed 6.06 ft/sec V/,/ =.952; 23.51 KTS Trial Speed 4.16 ft/sec V/L =.655; 16.18 KTS MODEL TEST CONDITIONS: EHP & SHP TESTS MODEL TEST CONDITIONS: EHP & SHP TESTS Draft: Mean: LWL Aft: Fwd: Draft: Mean: LWL Aft: Fwd: Turbulence Bow Trip Wire Temp: 67, 75~F Turbulence Bow and Stern Trip Wire Temp: 67 ~ 75F MODEL CHARACTERISTICS MODEL CHARACTERISTICS LBP/LWL CpA.648 B/H 2.5 LCB, LBP 1.5A of. LBP/LWL CpA.724 B/H 2.5 LCB, LBP 1.5 of LE/LBP 0.5 Cpv.850 LCF LBP LE/LBP.350 CpV.907 LCF, LBP LX/LBP 0 CpvF.910 L/V/3 6.165 LX/LBP.210 CpVF.961 L/V / 3 LR/LBP 0.5 CPVA.802 S/V2/3 6.481 LR/LBP.440 CPVA.856 S/V2/3 6.090 CB.60 CW.706 KR = R/i~/ 0.229 CB.75 cw.827 KR = R//CX.977 CWF.624 CiT.543 CX.990 CWF.817 CiT Cp.614 CWA.788 Cp.758 CWA.838 CpF.581 L/B 7.5 1/2 aE 7.0 CpF.792 L/B 6.75 1/2 0E 22.5 *Tank cross-sectional area = 190 sq ft.

TABLE 2 PROPELLER DATA PROP. UM No. 1 UM No. 2 PARENT DTMB No. 3378 DTMB No. 3379 DIAMETER (d), inches 6.272 6.969 PITCH (p), inches 7.195 (6.742)* 7.250 (7.143)* CHARACTERISTICS PITCH-DIAMETER RATIO, P/D 1.147 (1.075)* 1.040 (1.025)* MEAN-WIDTH RATIO, MWR 0.261 0.225 EFFECTIVE AREA-DISC AREA RATIO, EA/DA 0.550 0.470 BLADE THICKNESS FRACTION, BTF 0.045 0.045 RAKE, DEGREES ARC 6.00 6.00 NO. OF BLADES 4 4 *Indicates equivalent values of parent propellers.

UNIVERSITY OF MICHIGAN 3 9015 03483 5622