Figs. 227, 228.
When long models are made with single spine, they need some simple wire supports to prevent springing up or down, and from left to right. Fig. 229 is 4' long and the spine is only 1/4"'x1/4" at the small end 1/4"x3/8" at the larger end. A little 1/16" oak veneer cut in strips 3/16" wide would be very serviceable for the purpose of support in trussing the long spine. It should stand 2" above and below the spine, and the same amount for the right and left brace, Fig. 230. The wires for these should extend about a foot on each side of these posts, and be attached to the spine with little tin anchors, as shown in Fig. 230, a.
Figs. 230, 231, 232.
The propeller shaft bearing is of metal and is lashed to the cross-piece, called the base, Fig. 231. It is not necessary to have two points of bearing for the shaft. The metal is about 1/16"x1/4"x1", bent as in Fig. 232, and lashed to the under side of the base. The planes are similar to those in the next model. 1"xl 1/2"x7 1/2" propeller blanks are used. Try about fourteen strands of 1/16" string rubber for each motor, seven rounds.
My favorite model aeroplane is shown in Fig. 233. It had made some very pretty flights when it took a notion to glide into a young man's bicycle as he was riding by. Well, there was no improvement on the aeroplane when the chain and spokes of the bicycle were thru with it.
The framework is light and is spread well at the rear. The two spines are 3/16"x1/4"x33" and they come together at the forward end, the vertical section being 1/4". Nine inches back from the front end is a cross-piece that is just under 1/8" in thickness, 1/4" wide and 2 1/2" long. The cross-piece is on the upper side of the spines, and is fastened by a small 1/4" brad, is lashed with thread and coated with glue or shellac. The other cross-piece is 1" forward from the rear end, is of the same dimensions in cross-section as the forward piece, but is 8" long and is secured in the same manner as the other, see Fig. 234. The framework is further stiffened by two fine wires that run diagonally from the ends of one cross-piece to the ends of the other. They are secured to the inside vertical face of the spines by means of small pieces of tin that have two small holes, one at each end, the one receives a 1/4" brad that is driven into the spine, while the wire is attached to the other hole. The little pieces of tin are about 3/16"x1/2" and are lashed to the spine in addition to the fastening by the small brad. This kind of fastening prevents slipping, also the cutting into the wood, either of which would destroy the efficiency of the wire. In order to increase the tension of the wire, a small turn-buckle is inserted, Fig. 235.
Figs. 234, 235, 236, 237.
The bearings for the propeller shafts are lashed to the outside face of the rear end of each spine, Fig. 236. The bearing is a piece of brass 1/16"x1/4"x1" and is bent to a right angle at the middle. A small hole is drilled for a brad into the side of the spine and the other hole is drilled to receive the propeller shaft, which is 1/16" steel wire. The shaft is bent into a hook after it passes thru the bearing. To prevent the rubber of the motor from touching the steel wire, which is injurious to the rubber, a small rubber hose is slipped over the hook. In this model, the propellers are pieces of veneer steamed and pressed into the spiral shape. The propeller shaft then is bent around the center of the propeller, has two little washers between this and the bearing, after which comes the covered hook, sec Fig. 237. A piece of tin 1/2" wide and 1 1/4"' long is folded about the propeller before the shaft is bent around. The shaft is soldered to the tin, the tin being secured by two' small brads and shellac. A small tin rudder with a small fold in its upper portion may be slipped over the back cross-piece, Fig. 238. The fore plane is made of very thin spruce, shaped like Fig. 239, and is bent up almost like a butterfly's wings, Fig. 240. The wood is less than 1/16" thick. A double hook as anchors for the double motors, is bent and secured about the fore end of the framework. The hooks are covered with the rubber hose, the same as the propeller shaft, Fig. 241. The large plane is 4 1/2" in the widest place and is 20" long. It is the shape of Fig. 242 in outline, the straight side being to the rear. The outline of the plane is a steel or brass spring wire 1/16" diameter and is spliced at the center of the long sides, being soldered at this point. The ends of the wire lap over an inch or more. There are but two ribs which are 5 1/2' from the outer ends. The ribs have a slight curve upward, most of it being near the free edge of the plane, Fig. 243. The e-nds of the ribs are bent at a right angle and are soldered to the outside framework of wire. The cover of the plane is made of prepared silk and is made 1/4" larger all around than the size of the outline of the wire frame. A 1/4" hem is then turned which gives strength to the edge. The cover is now over cast with needle and thread to the framework, stretching fairly tight.
Figs. 239. 240.
The framework of the large plane is not secured directly to the wooden framework of the model, but is soldered to wire loops that in turn lie flat on top of the spines of the frame, Fig. 242, a, a. This gives opportunity to tie with string so as to try out the model. If it is too far forward, it can be slipped back and vice versa; when the correct position is located, it is permanently wired to the wooden framework. The fore plane is attached by means of rubber string. This is known as the Mann monoplane, and is a commercial product.
The propellers will be further discussed in the next chapter.