CHAPTER XI GEARED MOTORSA MORE accurate control may be gained over a strand motor by using gear wheels. Both their speed and duration may be increased indefinitely. The gear will restrain a powerful motor from "racing," acting much the same as the governor of an ordinary engine. Still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration.The geared wheels and the frames for mounting them will be found to add very little weight, and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor. Gears may be installed upon any ordinary motor base. Here is a fascinating field for experiment.The great advantage of the geared motor lies, of course, in the fact that it enables you to divide up your rubber motor into smaller groups of strands. As you increase the power by adding more rubber, you of course cut down the number of the turns it will take. A motor forty inches in length, comprising six strands of rubber, one-eighth of an inch square, may be twisted to about one thousand turns. Double the number of strands and you will find that you cannot get more than five hundred turns with safety. Double the diameter of your motor one more and it cannot be twisted more than to two hundred times.Now it is clear that if the motor consists of two groups of six strands each, and the axles be geared together, it may be wound up with one thousand turns while the power exerted will be that of the twelve strands. A motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number, or eighteen strands, and so on.As a general rule, it may be laid down, that by dividing your motor you double the number of revolutions. The heavier the motor the greater is the vibration in unwinding, and as you have doubtless discovered, a model which vibrates in flight offers a greatly increased resistance to the air. The geared motor cuts the vibration in half, or a third, as the case may be. Incidentally, this renders your motor practically noiseless.The resistance offered by a set of smoothly-running geared wheels is slight, and may be compensated by adding more strands to the motor. In mounting them use the same care as used in the shafts of ordinary motors. By mounting them on a simple metal frame the friction may be cut down still further. This mechanism, moreover, is so slight that you can afford to select substantial material for the purpose. The clock wheels used in most of our American clocks are too thin for the purpose and easily slip apart.A wheel one-sixteenth of an inch thick will add little weight to your model and will run much more smoothly. They may be bought very cheaply from clockmakers. The ingenious miniature ball bearings constructed for model aeroplanes are excellent for mounting gears, but they are not essential by any means, and the ordinary arrangement of washers used for motor axles will be delicate enough for gear adjustments. Complete sets of gear wheels mounted on metal frames, ready to be attached to the motor bases, may be purchased from the supply houses, but they are so simple that almost any bright boy can construct them for himself.In experimenting with gears it will be well to begin with but two sets of strands with gears of the same number of teeth. Several models equipped in this way have been flown with success in America. The best flights are those made by a model built by Mr. Frank Schoeber of New York, a winner in several competitions. Mr. Schoeber's model is driven by two motors of three strands each. He uses wheels of the same size and number of teeth. The support on which the gear wheels are mounted must be perfectly rigid, since any play will result in a serious loss of power through increased friction.Compressed-air motors have not yet been developed to a form practical for use in small model aeroplanes.An aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyAn aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyA remarkable model built by John CaresiA number of inventors are at work on this problem and high hopes are entertained that a practical form of compressed-air engine will soon be invented. An unlimited supply of compressed air may of course be carried without adding to the weight of the model. It costs nothing again to get a supply. Anyone with a bicycle pump can get up enough energy for his model as easily as he can inflate a bicycle tire. The best compressed-air engines at present weigh from one-third to one-half as much as the model they drive, and will run only from ten to thirty seconds.Spring motors hold out a promise for the model aeroplane builder. A number of fascinating experiments have been made to utilize the power of a coil spring. One young aviator mounted the spring of an ordinary shade roller upon a model aeroplane. The spring was connected up for a direct drive, a single propeller being used. It was found that such a spring could turn fifty times, storing up a relatively large amount of energy. Once released, however, it unwound with startling rapidity. The unwinding process was so rapid that the propeller spun through the air without taking hold or exerting any appreciable driving power.A propeller of very high pitch was employed, but with the same results. Evidently a spring of this nature is not practical. Experiments have been made in Germany, however, with coil springs better suited for model aeroplanes, with satisfactory results. Since trolley cars have been driven for considerable distances by energy wound up in coil springs, the model aeroplane should be able to take advantage of this elasticity. Doubtless another year will find model aeroplanes flying by energy stored in this way.The Petrol motors are now offered for sale in sizes suitable for model aeroplanes by several firms. A motor developing one-half of one horsepower weighs but little. The principal difficulty of these little power plants is that they set up a more or less violent vibration which racks the entire machine and renders a stable flight difficult. To set up one of these engines and adjust it to so delicate a task requires the highest engineering skill. Unless one has had such experience it will be well to avoid such experiments for the present at least. As a rule the engines are used to equip scale models which are not intended to fly. The beautiful model illustrated on the cover of this volume built by Mr. Karl H. De Leon is equipped with a rotary Knome engine especially imported.
CHAPTER XI GEARED MOTORSA MORE accurate control may be gained over a strand motor by using gear wheels. Both their speed and duration may be increased indefinitely. The gear will restrain a powerful motor from "racing," acting much the same as the governor of an ordinary engine. Still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration.The geared wheels and the frames for mounting them will be found to add very little weight, and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor. Gears may be installed upon any ordinary motor base. Here is a fascinating field for experiment.The great advantage of the geared motor lies, of course, in the fact that it enables you to divide up your rubber motor into smaller groups of strands. As you increase the power by adding more rubber, you of course cut down the number of the turns it will take. A motor forty inches in length, comprising six strands of rubber, one-eighth of an inch square, may be twisted to about one thousand turns. Double the number of strands and you will find that you cannot get more than five hundred turns with safety. Double the diameter of your motor one more and it cannot be twisted more than to two hundred times.Now it is clear that if the motor consists of two groups of six strands each, and the axles be geared together, it may be wound up with one thousand turns while the power exerted will be that of the twelve strands. A motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number, or eighteen strands, and so on.As a general rule, it may be laid down, that by dividing your motor you double the number of revolutions. The heavier the motor the greater is the vibration in unwinding, and as you have doubtless discovered, a model which vibrates in flight offers a greatly increased resistance to the air. The geared motor cuts the vibration in half, or a third, as the case may be. Incidentally, this renders your motor practically noiseless.The resistance offered by a set of smoothly-running geared wheels is slight, and may be compensated by adding more strands to the motor. In mounting them use the same care as used in the shafts of ordinary motors. By mounting them on a simple metal frame the friction may be cut down still further. This mechanism, moreover, is so slight that you can afford to select substantial material for the purpose. The clock wheels used in most of our American clocks are too thin for the purpose and easily slip apart.A wheel one-sixteenth of an inch thick will add little weight to your model and will run much more smoothly. They may be bought very cheaply from clockmakers. The ingenious miniature ball bearings constructed for model aeroplanes are excellent for mounting gears, but they are not essential by any means, and the ordinary arrangement of washers used for motor axles will be delicate enough for gear adjustments. Complete sets of gear wheels mounted on metal frames, ready to be attached to the motor bases, may be purchased from the supply houses, but they are so simple that almost any bright boy can construct them for himself.In experimenting with gears it will be well to begin with but two sets of strands with gears of the same number of teeth. Several models equipped in this way have been flown with success in America. The best flights are those made by a model built by Mr. Frank Schoeber of New York, a winner in several competitions. Mr. Schoeber's model is driven by two motors of three strands each. He uses wheels of the same size and number of teeth. The support on which the gear wheels are mounted must be perfectly rigid, since any play will result in a serious loss of power through increased friction.Compressed-air motors have not yet been developed to a form practical for use in small model aeroplanes.An aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyAn aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyA remarkable model built by John CaresiA number of inventors are at work on this problem and high hopes are entertained that a practical form of compressed-air engine will soon be invented. An unlimited supply of compressed air may of course be carried without adding to the weight of the model. It costs nothing again to get a supply. Anyone with a bicycle pump can get up enough energy for his model as easily as he can inflate a bicycle tire. The best compressed-air engines at present weigh from one-third to one-half as much as the model they drive, and will run only from ten to thirty seconds.Spring motors hold out a promise for the model aeroplane builder. A number of fascinating experiments have been made to utilize the power of a coil spring. One young aviator mounted the spring of an ordinary shade roller upon a model aeroplane. The spring was connected up for a direct drive, a single propeller being used. It was found that such a spring could turn fifty times, storing up a relatively large amount of energy. Once released, however, it unwound with startling rapidity. The unwinding process was so rapid that the propeller spun through the air without taking hold or exerting any appreciable driving power.A propeller of very high pitch was employed, but with the same results. Evidently a spring of this nature is not practical. Experiments have been made in Germany, however, with coil springs better suited for model aeroplanes, with satisfactory results. Since trolley cars have been driven for considerable distances by energy wound up in coil springs, the model aeroplane should be able to take advantage of this elasticity. Doubtless another year will find model aeroplanes flying by energy stored in this way.The Petrol motors are now offered for sale in sizes suitable for model aeroplanes by several firms. A motor developing one-half of one horsepower weighs but little. The principal difficulty of these little power plants is that they set up a more or less violent vibration which racks the entire machine and renders a stable flight difficult. To set up one of these engines and adjust it to so delicate a task requires the highest engineering skill. Unless one has had such experience it will be well to avoid such experiments for the present at least. As a rule the engines are used to equip scale models which are not intended to fly. The beautiful model illustrated on the cover of this volume built by Mr. Karl H. De Leon is equipped with a rotary Knome engine especially imported.
CHAPTER XI GEARED MOTORSA MORE accurate control may be gained over a strand motor by using gear wheels. Both their speed and duration may be increased indefinitely. The gear will restrain a powerful motor from "racing," acting much the same as the governor of an ordinary engine. Still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration.The geared wheels and the frames for mounting them will be found to add very little weight, and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor. Gears may be installed upon any ordinary motor base. Here is a fascinating field for experiment.The great advantage of the geared motor lies, of course, in the fact that it enables you to divide up your rubber motor into smaller groups of strands. As you increase the power by adding more rubber, you of course cut down the number of the turns it will take. A motor forty inches in length, comprising six strands of rubber, one-eighth of an inch square, may be twisted to about one thousand turns. Double the number of strands and you will find that you cannot get more than five hundred turns with safety. Double the diameter of your motor one more and it cannot be twisted more than to two hundred times.Now it is clear that if the motor consists of two groups of six strands each, and the axles be geared together, it may be wound up with one thousand turns while the power exerted will be that of the twelve strands. A motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number, or eighteen strands, and so on.As a general rule, it may be laid down, that by dividing your motor you double the number of revolutions. The heavier the motor the greater is the vibration in unwinding, and as you have doubtless discovered, a model which vibrates in flight offers a greatly increased resistance to the air. The geared motor cuts the vibration in half, or a third, as the case may be. Incidentally, this renders your motor practically noiseless.The resistance offered by a set of smoothly-running geared wheels is slight, and may be compensated by adding more strands to the motor. In mounting them use the same care as used in the shafts of ordinary motors. By mounting them on a simple metal frame the friction may be cut down still further. This mechanism, moreover, is so slight that you can afford to select substantial material for the purpose. The clock wheels used in most of our American clocks are too thin for the purpose and easily slip apart.A wheel one-sixteenth of an inch thick will add little weight to your model and will run much more smoothly. They may be bought very cheaply from clockmakers. The ingenious miniature ball bearings constructed for model aeroplanes are excellent for mounting gears, but they are not essential by any means, and the ordinary arrangement of washers used for motor axles will be delicate enough for gear adjustments. Complete sets of gear wheels mounted on metal frames, ready to be attached to the motor bases, may be purchased from the supply houses, but they are so simple that almost any bright boy can construct them for himself.In experimenting with gears it will be well to begin with but two sets of strands with gears of the same number of teeth. Several models equipped in this way have been flown with success in America. The best flights are those made by a model built by Mr. Frank Schoeber of New York, a winner in several competitions. Mr. Schoeber's model is driven by two motors of three strands each. He uses wheels of the same size and number of teeth. The support on which the gear wheels are mounted must be perfectly rigid, since any play will result in a serious loss of power through increased friction.Compressed-air motors have not yet been developed to a form practical for use in small model aeroplanes.An aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyAn aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyA remarkable model built by John CaresiA number of inventors are at work on this problem and high hopes are entertained that a practical form of compressed-air engine will soon be invented. An unlimited supply of compressed air may of course be carried without adding to the weight of the model. It costs nothing again to get a supply. Anyone with a bicycle pump can get up enough energy for his model as easily as he can inflate a bicycle tire. The best compressed-air engines at present weigh from one-third to one-half as much as the model they drive, and will run only from ten to thirty seconds.Spring motors hold out a promise for the model aeroplane builder. A number of fascinating experiments have been made to utilize the power of a coil spring. One young aviator mounted the spring of an ordinary shade roller upon a model aeroplane. The spring was connected up for a direct drive, a single propeller being used. It was found that such a spring could turn fifty times, storing up a relatively large amount of energy. Once released, however, it unwound with startling rapidity. The unwinding process was so rapid that the propeller spun through the air without taking hold or exerting any appreciable driving power.A propeller of very high pitch was employed, but with the same results. Evidently a spring of this nature is not practical. Experiments have been made in Germany, however, with coil springs better suited for model aeroplanes, with satisfactory results. Since trolley cars have been driven for considerable distances by energy wound up in coil springs, the model aeroplane should be able to take advantage of this elasticity. Doubtless another year will find model aeroplanes flying by energy stored in this way.The Petrol motors are now offered for sale in sizes suitable for model aeroplanes by several firms. A motor developing one-half of one horsepower weighs but little. The principal difficulty of these little power plants is that they set up a more or less violent vibration which racks the entire machine and renders a stable flight difficult. To set up one of these engines and adjust it to so delicate a task requires the highest engineering skill. Unless one has had such experience it will be well to avoid such experiments for the present at least. As a rule the engines are used to equip scale models which are not intended to fly. The beautiful model illustrated on the cover of this volume built by Mr. Karl H. De Leon is equipped with a rotary Knome engine especially imported.
A MORE accurate control may be gained over a strand motor by using gear wheels. Both their speed and duration may be increased indefinitely. The gear will restrain a powerful motor from "racing," acting much the same as the governor of an ordinary engine. Still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration.
The geared wheels and the frames for mounting them will be found to add very little weight, and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor. Gears may be installed upon any ordinary motor base. Here is a fascinating field for experiment.
The great advantage of the geared motor lies, of course, in the fact that it enables you to divide up your rubber motor into smaller groups of strands. As you increase the power by adding more rubber, you of course cut down the number of the turns it will take. A motor forty inches in length, comprising six strands of rubber, one-eighth of an inch square, may be twisted to about one thousand turns. Double the number of strands and you will find that you cannot get more than five hundred turns with safety. Double the diameter of your motor one more and it cannot be twisted more than to two hundred times.
Now it is clear that if the motor consists of two groups of six strands each, and the axles be geared together, it may be wound up with one thousand turns while the power exerted will be that of the twelve strands. A motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number, or eighteen strands, and so on.
As a general rule, it may be laid down, that by dividing your motor you double the number of revolutions. The heavier the motor the greater is the vibration in unwinding, and as you have doubtless discovered, a model which vibrates in flight offers a greatly increased resistance to the air. The geared motor cuts the vibration in half, or a third, as the case may be. Incidentally, this renders your motor practically noiseless.
The resistance offered by a set of smoothly-running geared wheels is slight, and may be compensated by adding more strands to the motor. In mounting them use the same care as used in the shafts of ordinary motors. By mounting them on a simple metal frame the friction may be cut down still further. This mechanism, moreover, is so slight that you can afford to select substantial material for the purpose. The clock wheels used in most of our American clocks are too thin for the purpose and easily slip apart.
A wheel one-sixteenth of an inch thick will add little weight to your model and will run much more smoothly. They may be bought very cheaply from clockmakers. The ingenious miniature ball bearings constructed for model aeroplanes are excellent for mounting gears, but they are not essential by any means, and the ordinary arrangement of washers used for motor axles will be delicate enough for gear adjustments. Complete sets of gear wheels mounted on metal frames, ready to be attached to the motor bases, may be purchased from the supply houses, but they are so simple that almost any bright boy can construct them for himself.
In experimenting with gears it will be well to begin with but two sets of strands with gears of the same number of teeth. Several models equipped in this way have been flown with success in America. The best flights are those made by a model built by Mr. Frank Schoeber of New York, a winner in several competitions. Mr. Schoeber's model is driven by two motors of three strands each. He uses wheels of the same size and number of teeth. The support on which the gear wheels are mounted must be perfectly rigid, since any play will result in a serious loss of power through increased friction.
Compressed-air motors have not yet been developed to a form practical for use in small model aeroplanes.
An aeroplane of simple construction that flies remarkably well, built by R. S. BarnabyAn aeroplane of simple construction that flies remarkably well, built by R. S. Barnaby
An aeroplane of simple construction that flies remarkably well, built by R. S. Barnaby
A remarkable model built by John Caresi
A number of inventors are at work on this problem and high hopes are entertained that a practical form of compressed-air engine will soon be invented. An unlimited supply of compressed air may of course be carried without adding to the weight of the model. It costs nothing again to get a supply. Anyone with a bicycle pump can get up enough energy for his model as easily as he can inflate a bicycle tire. The best compressed-air engines at present weigh from one-third to one-half as much as the model they drive, and will run only from ten to thirty seconds.
Spring motors hold out a promise for the model aeroplane builder. A number of fascinating experiments have been made to utilize the power of a coil spring. One young aviator mounted the spring of an ordinary shade roller upon a model aeroplane. The spring was connected up for a direct drive, a single propeller being used. It was found that such a spring could turn fifty times, storing up a relatively large amount of energy. Once released, however, it unwound with startling rapidity. The unwinding process was so rapid that the propeller spun through the air without taking hold or exerting any appreciable driving power.
A propeller of very high pitch was employed, but with the same results. Evidently a spring of this nature is not practical. Experiments have been made in Germany, however, with coil springs better suited for model aeroplanes, with satisfactory results. Since trolley cars have been driven for considerable distances by energy wound up in coil springs, the model aeroplane should be able to take advantage of this elasticity. Doubtless another year will find model aeroplanes flying by energy stored in this way.
The Petrol motors are now offered for sale in sizes suitable for model aeroplanes by several firms. A motor developing one-half of one horsepower weighs but little. The principal difficulty of these little power plants is that they set up a more or less violent vibration which racks the entire machine and renders a stable flight difficult. To set up one of these engines and adjust it to so delicate a task requires the highest engineering skill. Unless one has had such experience it will be well to avoid such experiments for the present at least. As a rule the engines are used to equip scale models which are not intended to fly. The beautiful model illustrated on the cover of this volume built by Mr. Karl H. De Leon is equipped with a rotary Knome engine especially imported.