§§1-2. Its primary importance both in rubber and power-driven models—Professor Langley's experiences. §3. Theoretical aspect of the question. §4. Means whereby more weight can be carried—How to obtain maximum strength with minimum weight. §5. Heavy models versus light ones.
§1. The chief function of a model in the medium in which it travels. §2. Resistance considered as load percentage. §3. How made up. §4. The shape of minimum resistance. §5. The case of rubber-driven models. §6. The aerofoil surface—Shape and material as affecting this question. §7. Skin friction—Its coefficient. §8. Experimental proofs of its existence and importance.
§1. Automatic stability essential in a flying model. §2. Theoretical researches on this question. §§3-6. A brief summary of the chief conclusions arrived at—Remarks on and deductions from the same—Conditions for automatic stability. §7. Theory and practice—Stringfellow—PÉnaud—Tatin—The question of Fins—Clarke's models—Some further considerations. §8. Longitudinal stability. §9. Transverse stability. §10. The dihedral angle. §11. Different forms of the latter. §12. The "upturned" tip. §13. The most efficient section.
§1. Some experiments with rubber cord. §2. Its extension under various weights. §3. The laws of elongation (stretching)—Permanent set. §4. Effects of elongation on its volume. §5. "Stretched-twisted" rubber cord—Torque experiments with rubber strands of varying length and number. §6. Results plotted as graphs—Deductions—Various relations—How to obtain the most efficient results—Relations between the torque and the number of strands, and between the length of the strands and their number. §7. Analogy between rubber and "spring" motors—Where it fails to hold. §8. Some further practical deductions. §9. The number of revolutions that can be given to rubber motors. §10. The maximum number of turns. §11. "Lubricants" for rubber. §12. Action of copper upon rubber. §12A. Action of water, etc. §12B. How to preserve rubber. §13. To test rubber. §14. The shape of the section. §15. Size of section. §16. Geared rubber motors. §17. The only system worth consideration—Its practical difficulties. §18. Its advantages.
§18A. Spring motors; their inferiority to rubber. §18B. The most efficient form of spring motor. §18C. Compressed air motors—A fascinating form of motor, "on paper." §18D. The pneumatic drill—Application to a model aeroplane—Length of possible flight. §18E. The pressure in motor-car tyres. §19. Hargraves' compressed air models—The best results compared with rubber motors. §20. The effect of heating the air in its passage from the reservoir to the motor—The great gain in efficiency thereby attained—Liquid air—Practical drawbacks to the compressed-air motor. §21. Reducing valves—Lowest working pressure. §22. The inferiority of this motor compared with the steam engine. §22A. Tatin's air-compressed motor. §23. Steam engine—Steam engine model—Professor Langley's models—His experiment with various forms of motive power—Conclusions arrived at. §24. His steam engine models—Difficulties and failures—and final success—The "boiler" the great difficulty—His model described. §25. The use of spirit or some very volatile hydrocarbon in the place of water. §26. Steam turbines. §27. Relation between "difficulty in construction" and the "size of the model." §28. Experiments in France. §29. Petrol motors.—But few successful models. §30. Limit to size. §31. Stanger's successful model described and illustrated. §32. One-cylinder petrol motors. §33. Electric motors.
§1. The position of the propeller. §2. The number of blades. §3. Fan versus propeller. §4. The function of a propeller. §5. The pitch. §6. Slip. §7. Thrust. §8. Pitch coefficient (or ratio). §9. Diameter. §10. Theoretical pitch. §11. Uniform pitch. §12. How to ascertain the pitch of a propeller. §13. Hollow-faced blades. §14. Blade area. §15. Rate of rotation. §16. Shrouding. §17. General design. §18. The shape of the blades. §19. Their general contour—Propeller design—How to design a propeller. §20. Experiments with propellers—Havilland's design for experiments—The author experiments on dynamic thrust and model propellers generally. §21. Fabric-covered screws. §22. Experiments with twin propellers. §23. The Fleming Williams propeller. §24. Built-up v. twisted wooden propellers
THE QUESTION OF SUSTENTATION. THE CENTRE OF PRESSURE.
§1. The centre of pressure—Automatic stability. §2. Oscillations. §3. Arched surfaces and movements of the centre of pressure—Reversal. §4. The centre of gravity and the centre of pressure. §5. Camber. §6. Dipping front edge—Camber—The angle of incidence and camber—Attitude of the Wright machine. §7. The most efficient form of camber. §8. The instability of a deeply cambered surface. §9. Aspect ratio. §10. Constant or varying camber. §11. Centre of pressure on arched surfaces
