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Report No. 387. The vertical wind tunnel of the National Advisory Committee for Aeronautics
Sept., 193~.]
BOOK REVIEWS.
397
organic chemistry, this book contains either chapters or sections devoted to such subjects as the proteins and their related compounds, the terpenes and camphors, the alkaloids, dyes, enzymes, toxins and antitoxins, hormones, and vitamins. This feature renders the treatise of especial value to the biologist and the premedical student as well as to persons who wish a comprehensive introduction to this extensive branch of chemistry. Another feature is an appendix on the "Consultation of Chemical Literature," chiefly in its organic aspects. Physicochemical relationships and industrial applications also receive attention in the text. JOSEPH S. HEPBURN. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS. Report No. 386. Maneuverability Investigation of an F6C- 4 Fighting Airplane, by C. H. Dearborn and H. W. Kirschbaum, 25 pages, illustrations, quarto. Washington, Government Printing Office, I931 , price twenty cents. In order to compare the relative maneuverability of two fighting airplanes and to accumulate additional data to assist in establishing a satisfactory criterion for the maneuverability of any airplane, the National Advisory Committee for Aeronautics, at the request of the Bureau of Aeronautics, Navy Department, has conducted maneuverability investigations on the F6C- 3 (water-cooled engine) and the F6C- 4 (air-cooled engine) airplanes. The investigation made on the F6C-3 airplane has been previously reported. This report contains the results of the investigation made on the F6C- 4 airplane. Measurements of air speed, angular velocity, linear acceleration, temperature, pressure, and the position of the controls were made for practically all the kinds of military maneuvers required of this type of airplane. Flight path coisrdinates were secured for most of the maneuvers by means of a special camera obscura developed for this investigation. The results are given in the form of curves, some showing the variation of the measured quantities with respect to time, others, the variation of some maximum quantities with respect to air speed. In addition, all maximum quantities are tabulated. A comparison of the results with those obtained in the investigation conducted on the F6C-3 airplane shows t h a t : with practically the same speed and control movement, the F6C-4 completed a loop in Io per cent less time than did the F6C-3; in dives the F6C- 3 increased its speed more rapidly than did the F6C-4; and the minimum radius of turn was found to be I35 feet at 61.5 miles per hour for the F6C-4, and I55 feet at 76 miles per hour for the F6C- 3. Report No. 387 . The Vertical Wind Tunnel of the National Advisory Committee for Aeronautics, by Carl J. Wenzinger and Thomas A. Harris, Io pages, illustrations, quarto. Washington, Government Printing Office, I93I , price ten cents. The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics is described in this report. The tunnel was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual spin of an airplane.
398
BOOK R E V I E W S .
[J. F. I.
Satisfactory air flow has been a t t a i n e d with a velocity t h a t is uniform over the jet to within :t= 0.5 per cent. The turbulence present in the tunnel has been compared with t h a t of several other tunnels by means of the results of sphere drag tests and was found to average well with the values of those tunnels. Included also in the report are comparisons of results of stable autorotation and of rollingmoment tests obtained both in the vertical tunnel and in the old horizontal 5-foot atmospheric tunnel. Report No. 388. Investigation of the Diaphragm-Type Pressure Cell by Theodore Theodorsen, I8 pages, illustrations quarto. Washington, Government Printing Office, I93I , price ten cents. This report relates to various improvements in the process of manufacture of the N. A. C. A. standard pressure cell. Like most pressure recording devices employing thin diaphragms, they would in general show considerable change in calibration with temperature and also some change of calibration with time or aging effect. Some instruments exhibited considerable internal friction. It was established t h a t the temperature dependency of the stiffness was due to difference in the thermal expansivlty between the diaphragm proper and the supporting body of the cell, and convenient methods for its compensation have been developed. The diaphragm is furnished with a small central bushing of a different metal, and it is possible to determine a size of this bushing which gives the diaphragm exactly the same thermal expansivity as the cell body. It was further established t h a t the internal hysteresis in the diaphragm was of a negligible magnitude a n d t h a t the observed lag was due, primarily, to the force of the hairspring on the stylus point. The resultant adoption of weaker hairsprings made it possible to extend the useful range of the instrument considerably downward. Satisfactory instruments having a range of less t h a n 3 inches of water were made possible. It was found t h a t the tendency to change calibration with time was caused, to a great extent, b y insufficient clamping of the diaphragm. The adoption of double copper gaskets improved this condition. T h e required diaphragm thickness and the desirable rate of mechanical magnification have been determined on the basis of several hundred tests. Report No. 389 . The Effect of Small Angles of Yaw and Pitch on the Characteristics of Airplane Propellers, b y Hugh B. Freeman, I I pages, illustrations, quarto, Washington, Government Printing Office, I93I , price ten cents. T h e subject tests were carried out in the 2o-foot wind tunnel of the National Advisory Committee for Aeronautics to determine the effect on the characteristics of a propeller of inclining the propeller axis at small angles to the relative wind. Tests were made of a full-scale propeller and fuselage combination a t four angles of yaw (o °, q- 5 °, -b Io °, a n d -}- I5°), and of a model propeller, nacelle, and wing combination at five angles of pitch (-- 5 °, o °, -I- 5 °, q- Io °, and -4- I5°). T h e results of the full-scale tests of a propeller and fuselage, without a wing, show t h a t the effect on the propeller performance is small. Similar results are shown by the model test data except t h a t where the propeller is directly in front of the wing there is a n appreciable decrease in effective t h r u s t and propulsive efficiency with increase of angle of pitch.
BOOK REVIEWS.
397
organic chemistry, this book contains either chapters or sections devoted to such subjects as the proteins and their related compounds, the terpenes and camphors, the alkaloids, dyes, enzymes, toxins and antitoxins, hormones, and vitamins. This feature renders the treatise of especial value to the biologist and the premedical student as well as to persons who wish a comprehensive introduction to this extensive branch of chemistry. Another feature is an appendix on the "Consultation of Chemical Literature," chiefly in its organic aspects. Physicochemical relationships and industrial applications also receive attention in the text. JOSEPH S. HEPBURN. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS. Report No. 386. Maneuverability Investigation of an F6C- 4 Fighting Airplane, by C. H. Dearborn and H. W. Kirschbaum, 25 pages, illustrations, quarto. Washington, Government Printing Office, I931 , price twenty cents. In order to compare the relative maneuverability of two fighting airplanes and to accumulate additional data to assist in establishing a satisfactory criterion for the maneuverability of any airplane, the National Advisory Committee for Aeronautics, at the request of the Bureau of Aeronautics, Navy Department, has conducted maneuverability investigations on the F6C- 3 (water-cooled engine) and the F6C- 4 (air-cooled engine) airplanes. The investigation made on the F6C-3 airplane has been previously reported. This report contains the results of the investigation made on the F6C- 4 airplane. Measurements of air speed, angular velocity, linear acceleration, temperature, pressure, and the position of the controls were made for practically all the kinds of military maneuvers required of this type of airplane. Flight path coisrdinates were secured for most of the maneuvers by means of a special camera obscura developed for this investigation. The results are given in the form of curves, some showing the variation of the measured quantities with respect to time, others, the variation of some maximum quantities with respect to air speed. In addition, all maximum quantities are tabulated. A comparison of the results with those obtained in the investigation conducted on the F6C-3 airplane shows t h a t : with practically the same speed and control movement, the F6C-4 completed a loop in Io per cent less time than did the F6C-3; in dives the F6C- 3 increased its speed more rapidly than did the F6C-4; and the minimum radius of turn was found to be I35 feet at 61.5 miles per hour for the F6C-4, and I55 feet at 76 miles per hour for the F6C- 3. Report No. 387 . The Vertical Wind Tunnel of the National Advisory Committee for Aeronautics, by Carl J. Wenzinger and Thomas A. Harris, Io pages, illustrations, quarto. Washington, Government Printing Office, I93I , price ten cents. The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics is described in this report. The tunnel was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual spin of an airplane.
398
BOOK R E V I E W S .
[J. F. I.
Satisfactory air flow has been a t t a i n e d with a velocity t h a t is uniform over the jet to within :t= 0.5 per cent. The turbulence present in the tunnel has been compared with t h a t of several other tunnels by means of the results of sphere drag tests and was found to average well with the values of those tunnels. Included also in the report are comparisons of results of stable autorotation and of rollingmoment tests obtained both in the vertical tunnel and in the old horizontal 5-foot atmospheric tunnel. Report No. 388. Investigation of the Diaphragm-Type Pressure Cell by Theodore Theodorsen, I8 pages, illustrations quarto. Washington, Government Printing Office, I93I , price ten cents. This report relates to various improvements in the process of manufacture of the N. A. C. A. standard pressure cell. Like most pressure recording devices employing thin diaphragms, they would in general show considerable change in calibration with temperature and also some change of calibration with time or aging effect. Some instruments exhibited considerable internal friction. It was established t h a t the temperature dependency of the stiffness was due to difference in the thermal expansivlty between the diaphragm proper and the supporting body of the cell, and convenient methods for its compensation have been developed. The diaphragm is furnished with a small central bushing of a different metal, and it is possible to determine a size of this bushing which gives the diaphragm exactly the same thermal expansivity as the cell body. It was further established t h a t the internal hysteresis in the diaphragm was of a negligible magnitude a n d t h a t the observed lag was due, primarily, to the force of the hairspring on the stylus point. The resultant adoption of weaker hairsprings made it possible to extend the useful range of the instrument considerably downward. Satisfactory instruments having a range of less t h a n 3 inches of water were made possible. It was found t h a t the tendency to change calibration with time was caused, to a great extent, b y insufficient clamping of the diaphragm. The adoption of double copper gaskets improved this condition. T h e required diaphragm thickness and the desirable rate of mechanical magnification have been determined on the basis of several hundred tests. Report No. 389 . The Effect of Small Angles of Yaw and Pitch on the Characteristics of Airplane Propellers, b y Hugh B. Freeman, I I pages, illustrations, quarto, Washington, Government Printing Office, I93I , price ten cents. T h e subject tests were carried out in the 2o-foot wind tunnel of the National Advisory Committee for Aeronautics to determine the effect on the characteristics of a propeller of inclining the propeller axis at small angles to the relative wind. Tests were made of a full-scale propeller and fuselage combination a t four angles of yaw (o °, q- 5 °, -b Io °, a n d -}- I5°), and of a model propeller, nacelle, and wing combination at five angles of pitch (-- 5 °, o °, -I- 5 °, q- Io °, and -4- I5°). T h e results of the full-scale tests of a propeller and fuselage, without a wing, show t h a t the effect on the propeller performance is small. Similar results are shown by the model test data except t h a t where the propeller is directly in front of the wing there is a n appreciable decrease in effective t h r u s t and propulsive efficiency with increase of angle of pitch.