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Aviation History
1925
1925 - 0017.PDF
JANUARY 8, 1925 TESTS OF ROTATING CYLINDERS* By ELLIOTT G. REID FOLLOWING on the publication in FLIGHT of November 27 and December 4 of the articles dealing with the Flettner " Rotor," we have received from Mr. G. W. Lewis, Director of Aeronautical Research in the United States, a copy of " American National Advisory Committee for Aeronautics Technical Note No. 209," which deals with tests on rotating cylinders. Extracts of this report are published below, lack of space preventing us from giving the report in full. The only omissions, however, are Figs. 2 and 3, which show the installation of the apparatus used for the tests, and Tables III and IV, giving' data of cross- cyliftder, and Tables V, VI and VII, giving data of compound strut. For all practical purposes the required data can be read off with sufficient accuracy from the graphs, Figs. 7-14 inclusive. We have, however, reproduced Figs. 15, 16 and 17, which show the flow around the smooth cylinder at an air speed of 5 m. per second and at rotational speeds of 600 r v m 1 200 r t> m and 2,400 r.p.m. " - " ' v' Mr. Lewis, in his covering letter, states that further tests are being made in the direct application of the rotatin°--cvlinderprinciple to actual aeroplane design.—ED. Introduction A COMBINATION of translation and circulation is the basic concept of the theory of airfoils proposed by Kutta, as well as those of Joukowski, von Mises, Lanchester and Prandtl (Reference 1). The tests described below constitute an attempt to measure the forces arising from controlled com- bination of these two types of flow. The observed data consist of drag and cross-wind forces, air speed, revolutions per minute of the cylinder and electrical input to the motor driving the cylinder. Individual observa- tions were made by bringing air speed and revolutions per minute to the desired values and measuring the other quan- tities simultaneously. The programme of test was as follows :—The circular cylinder was tested at an airspeed of 15 m./s. (49-2 ft./sec), and increasing rotative speeds until the power limit of the drive motor was reached. The air speed was then reduced to 10 m./s. (32-8 ft./sec.) and the process repeated. It became necessary to go to 7 (23) and, finally, 5 m./s. (16-4 ft./sec.) in order to reach a maximum " lift drag " ratio. The performance of the cross cylinder, at 15 m./s. (49-2 ft.'/ sec.), was very erratic. A marked hysteresis loop made its • Technical Note No. 209 of American National Advisory Committeefor Aeronautics. Y4Ji"D- Circular cylinder Crosscylinder Compound strut * FIG. I. TESTS OF ROTATING CYLINDERS : Fig. 1 :Dimensions of cylinders and compound strut used in the experiments. .-.". appearance in the vector diagram of resultant air force, and, when excessive vibration was encountered at 3,000 r.p.m. ana 10 m./s. (32-8 ft./sec.) air speed, the work on this model was discontinued. R.P.M. 25 500 900 1,020 1,115 1,240 1,300 1,300 1,400 1,500 1,500 1,600 1,600 1,700 1,700 1,700 1,780 1,800 1,900 1,900 1,900 2,000 2,080 2,100 2,200 2 2°0 2^300 2,420 2,500 2,600 2 620 2>00 1,300 1,500 1,700 1,900 2,100 2,300 2,500 2,700 2,900 1,800 2,100 2,400 2,700 3,000 3,300 3,600 1,800 2,100 2,400 2,700 3,000 3,300 3,600 D kg 1136 1-136 1026 •942 •852 •111 •754 •747 •740 •744 •740 •744 •744 •759 •751 •750 •751 •754 •757 •751 •757 •759 •765 •764 •764 •787 •772 •754 •742 •729 •724 •710 •353 •351 •338 •331 •322 •324 •332 •334 •346 •085 •105 •130 •151 •168 •188 •196 •167 •173 •181 •197 •222 •256 •287 TABLE I CWF kg -•010 + -010 -020 -•022 -•007 +••003 •018 •043 •150 •283 •305 •400 •453 •608 •625 •598 •660 •673 •798 •815 •758 •S73 •868 •997 1073 1158 1-188 1-278 1-338 1-468 1-303 1-578 + •308 •418 •636 •758 - -97S 1083 1-293 1-403 1-443 •605 •820 •995 1110 1-170 1-250 1-295 •660 •860 1140 1-365 1-700 1-945 2-210 —Circular cD •925 •925 •835 •766 •693 •632 •614 •608 •602 •605 •602 •605 •605 •618 •611 •610 •611 •614 •616 •611 •616 •618 •622 •622 •622 •640 •628 •614 •604 •593 •589 •578 •646 •642 •618 •605 •589 •593 •607 •611 •633 •622 •769 •952 1 • 105 1-230 1-376 1-434 •624 •646 •676 •736 •829 •956 1070 Cylinder. Ccw -008 -•008 -016 -018 -006 + •002 •014 •035 •122 •230 •248 •326 •369 •495 •508 •487 •537 •548 •650 •663 •617 •710 •706 •811 •873 •942 •967 1-040 1089 1194 1-060 1-284 •563 •764 1163 1-386 1-789 1-980 2-362 2-564 2-639 4-43 6-00 7-28 8-13 8-57 9-15 9-48 2-46 3-21 4-26 5 10 6-35 7-26 8-25 V (m/s) 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 10 10 10 10 10 10 10 10 10 5 5 5 5 5 5 5 7 7 7 1 7 7 7 r •010 •200 •360 •408 •460 •496 •520 •520 •560 •600 •600 •640 •640 •680 •680 •680 •712 •720 •760 •760 •760 •800 •832 •840 •880 •888 •920 •968 1-000 1-040 1-048 1-080 •780 •900 1020 1-140 1-260 1-380 1-500 1-620 1-740 2-16 2-51 2-87 3-23 3-59 3-95 4-32 1-54 1-79 2-05 2-30 2-56 2-82 3 07 S = 0-1741 m2; q= 1-535 kg./m- (5 m/s.), 3-01 kg/m3 (7 m/s.), 6-15 kg./m"- (10 m/s.) and 13-81 kg./m2 (15 m/s.).
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