Boys' Book of Model Boats

d-water boats still employ side paddle-wheels, while oce

the wheel goes around the paddle dips into the water and pushes the boat forward. If the

t what the paddle does in the water. It dips into the water and pushes against it. It must be remembered, however, that water is unlike a solid substance and it "gives." When a man places his oar against the bank and pushes it, the bank does n

al screw, because its theory of operation is exactly the same. A wood screw, when turned, forces itself into wood. A propeller, when turned, forces itself (and thereby th

he water back tends to produce a forward motion of the propeller, and in this way the boat on which the propeller is mounted moves through the water. The propeller is caused to revolve by a steam-engine, steam-turbi

stance the screw moves forward will depend entirely upon the distance between the threads. The distance between the threads is

peller with a pitch of ten inches should move ten inches through the water at each revolution. However, there is a certain amount of "slip," and a propeller does not actually advance

his purpose. Next, a block, as shown at B, is carefully carved out so that the propeller can be hammered down into the depression. The same block is used for the t

od of cutting the slots in the hub is shown at D, Fig. 37. The hub is clamped between two boards placed in the vise, and a hacksaw is used to cut a slot in the hub. The hub is then turned around one third of a revolution, and another slot cut, using the same saw-marks in the boards, so tha

ractical merely to bore a hole in the hull of the boat to put the propeller-shaft through. In this way water would surely leak into the hull and the

re will be a space between it and the tube. Before the propeller-shaft is put in place it is well smeared with vaseline, and when it is placed in the tube the space between the shaft and the tube will be completely filled with it. This will prevent water from entering. Owing to the fact

to the low power of the rubber-band motor. The opposite end of the propeller-shaft is bent into a hook, and the rubber bands run from this to another hook placed at the bow of the boat. The rubber bands may be similar to those employed by model airplane builders. The motor, of course, must be wound up by turning the propeller around until the b

little power motor, a very reliable method of propulsion is made possible. The boat must have sufficient displacement to accommodate the weight of the dry-cells and storage

dry-cells, is shown in Fig. 41. The connections for the motor are given clea

s are extremely heavy and occupy considerable space. They are also costly, s

on of three to one. It will be seen that the propeller-tube is strapped within a strip of brass to a small cross-piece nailed to the bottom board of the hull. The hull is of the built-up type, and the other three boards that go to make it up are not shown. When the three boards are glued in place, a brass strip is run across the to

to shape on a rod, and a drop of solder holds it to the propeller and motor shafts. In the method of propulsion shown in Fig. 44 the armature-shaft of the motor must be perfectly in line with the propeller-shaft, or the gears will bind and unsatisfactory operation of the motor will res

llustrated in Fig. 48. This method is so simple th

e clockworks to install in a boat. Oftentimes it will be possible to salvage the works of an old alarm-clock, providing the main-spring is int

ommend it as strongly as the electric method for reliability. Of course, steam is a more power

ces are forced in place solder is carefully flowed around their edges. The brass rod is then threaded at each end and placed concentrically within the boiler, as shown in Fig. 49. A nut is placed on each end of this rod and tightened. The nut is then soldered in place. This brass rod, called a stay-rod, prevents the end of the boiler from blowing out when the steam pressure has reached its maximum value. Three holes are

k by means of which it is filled with denatured alcohol. A little pipe runs from the fuel-tank to the burner. It is advisable, if possible, to place a small valve in this pipe to cut off the fuel supply when necessary. The only other method of putting the burner out would be to stand it on its end. The burner consists of a rectangular tin box with a top cut out as illustrated. A piece of brass or

ery simple engine of the oscillation type, and there should be little trouble in making it. A more

over and cylinder head, must be cut to fit inside the cylinder. These should be cut to shape from 1/16 inch brass, and a hole drilled in the cylinder head 1/8 inch i

little piece is cut and drilled as shown in the drawing. Before it is soldered in place on the piston-rod the cylinder-end cover should be placed on the rod. Both the piston and the cylinder-end cover can then be placed inside the cylinder, and the piston-end cover is soldered in place. Before final a

his piece as shown in the drawing. The hole at the top is the steam entrance and exhaust for the engine; that is, when the cylinder is at one side steam enters this hole, and when the crank throws the cylinder over to the other side steam leaves through the same hole a

the inlet hole in the block under consideration. Steam then enters the cylinder and forces the piston down. This turns the crank around, and the crank in turn pulls the piston over to the opposite side, so that the hole in the first piston block of the cylinder now comes in line with the exhaust hole on the second cylinder block. The

block and the engine standard. A small spring is placed over the protruding end of the pivot and a nut put in place. By turning this nut the pressure on the face of the two cylinder blocks can be adjusted, and the model engineer must always remember that the pressure on these springs must be g

that the sheet brass that makes up the engine standard is not thick enough to offer a good bearing for the crank. The crank is bent to shape from a piece of 1/8-inch brass rod

54. Two other holes 1/8 inch in diameter are drilled in the flywheel as illustrated, and two small brass pins are cut out from 1/8-inch brass

in the boiler has reached a sufficient pressure the engine crank should be given a couple of twists in order to start it. Before operating the engine a little lubricating oil should be

rted and cannot be made to run, take the burner from under the boiler so that steam will cease to be generated. With the safety-valv