Chapter III: Section II: Other Forms of Motors

§ 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_ 39

CHAPTER V.

PROPELLERS OR SCREWS.

§ 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 52

CHAPTER VI.

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 78

CHAPTER VII.

MATERIALS FOR AEROPLANE
CONSTRUCTION.

§ 1. The choice strictly limited. § 2. Bamboo. § 3.
Ash--spruce-- whitewood--poplar. § 4. Steel. § 5. Umbrella
section steel. § 6. Steel wire. § 7. Silk. § 8. Aluminium and
magnalium. § 9. Alloys. § 10. Sheet ebonite--Vulcanized
fibre--Sheet celluloid--Mica 86

CHAPTER VIII.

HINTS ON THE BUILDING OF MODEL
AEROPLANES.

§ 1. The chief difficulty to overcome. § 2. General
design--The principle of continuity. § 3. Simple monoplane.
§ 4. Importance of soldering. § 5. Things to avoid. § 6.
Aerofoil of metal--wood--or fabric. § 7. Shape of aerofoil.
§ 8. How to camber an aerocurve without ribs. § 9. Flexible
joints. § 10. Single surfaces. § 11. The rod or tube carrying
the rubber motor. § 12. Position of the rubber. § 13. The
position of the centre of pressure. § 14. Elevators and
tails. § 15. Skids _versus_ wheels--Materials for skids.
§ 16. Shock absorbers, how to attach--Relation between the
"gap" and the "chord" 93

CHAPTER IX.

THE STEERING OF THE MODEL.

§ 1. A problem of great difficulty--Effects of propeller
torque. § 2. How obviated. § 3. The two-propeller
solution--The reason why it is only a partial success. § 4.
The _speed_ solution. § 5. Vertical fins. § 6. Balancing tips
or ailerons. § 7. Weighting. § 8. By means of transversely
canting the elevator. § 9. The necessity for some form of
"keel" 105

CHAPTER X.

THE LAUNCHING OF THE MODEL.

§ 1. The direction in which to launch them. § 2. The
velocity--wooden aerofoils and fabric-covered
aerofoils--Poynter's launching apparatus. § 3. The launching
of very light models. § 4. Large size and power-driven
models. § 5. Models designed to rise from the
ground--Paulhan's prize model. § 6. The setting of the
elevator. § 7. The most suitable propeller for this form of
model. § 8. Professor Kress' method of launching. § 9. How to
launch a twin screw model. § 10. A prior revolution of the
propellers. § 11. The best angle at which to launch a model 109

CHAPTER XI.

HELICOPTER MODELS.

§ 1. Models quite easy to make. § 2. Sir George Cayley's
helicopter model. § 3. Phillips' successful power-driven
model. § 4. Toy helicopters. § 5. Incorrect and correct way
of arranging the propellers. § 6. Fabric covered screws. § 7.
A design to obviate weight. § 8. The question of a fin or
keel. 113

CHAPTER XII.

EXPERIMENTAL RECORDS 116

CHAPTER XIII.

MODEL FLYING COMPETITIONS.

§ 1. A few general details concerning such. § 2. Aero Models
Association's classification, etc. § 3. Various points to be
kept in mind when competing 119