Page:Sim popular-mechanics 1910-06 13 6.pdf/29

 779 proven so easy to balance as the monoplane. The principal objection to it up to within a short time has been the difficulty of bracing the plane. With the biplane the trussing was of great service in this connection. But with the guide wires firmly fixed from the frame to the wings there is little probability of any difficulty with the Santos-Dumont type.

At the very beginning it might be well to state that the greatest items of expense in the construction of the machine will be the motor and the propeller. Santos-Dumont used a Darracq motor of 30 hp. in his record-breaking flight, although he had previously made some fine flights with a 17-hp. motor. There are American motors which will do just as well, probably. and will undoubtedly be much cheaper, as the importation of one from France involves the expense of freight and customs duties.

The construction of the propeller is vitally important, and we would advise that this be purchased.

A good place at which to start would be the vertical rudder, Plate III. The thickness of the bamboo there given is the maximum one. The stronger and heavier portions are used for the centers where the joints are formed and the strain is heaviest. The detailed drawing C on this plate shows the manner in which the cloth is attached to the framework by gauge No. 21 piano wire. As it is done at this point so it should be done on all parts of the monoplane. After having sewn the piano wire into the outer edge of the cloth, taking care to leave open the part where the wire is to be attached to the framework, the wire should be stretched to get it to the extremity, and then dropped into the slot made for it to rest in on the outer end of the bamboo. Thus the planes of cloth are well stretched, and are held firmly in place, adding to the strength of the machine. The same end could not be accomplished nearly as well by first attaching the wire and then sewing the cloth thereon. This applies to the wings also where every added bit of strength and firmness adds to the successful completion. Slots are made at the end of the bamboos for the wires to slip into and be held fast. It is a good idea to put a cork into the hollow ends of the rods, and to cut the slots in both at the same time. The brass wire, gauge No. 25, should also be wound around the rod just below the end of the slot. This prevents the piano wire on which the cloth is sewn from splitting the rods. It may seem that this arrangement is crude, yet it is the way that Santos-Dumont made the ends when he flew from St. Cyr to Buc. Later on—he had a number of "Demoiselles," and small breaks happened now and then—he put a little metal cap over the ends of the rods. Slots were made in these caps to receive the wires. We have described the former because it is by far the easier way for amateur airship builders.

M. Santos-Dumont about to Start Flight in the "Demoiselle" The cloth used by Santos-Dumont was a very finely woven silk. Silk does not rot as easily as cotton and is considerably stronger. Silk has the great objection of expense, however, and it would probably be as well to use percale or strong muslin, care being taken to secure the best grade of closely woven and unbleached goods.