The usual formula for this smoke-tracer composition consists of -
A slight deviation from this formula, as shown by the following composition, is also used with satisfactory results:
This composition is hand mixed and passed through a sieve in a manner similar to the mixing of the compositions previously discussed. Little cups, attached to a rack holding sufficient composition for the three or four successive charges, are used to introduce the composition into the carton. When the composition has been rammed into place a clay heading is forced into position in a manner similar to that described previously.
The match is inserted in holes drilled in the loaded carton.
Figure 33 shows the operator drilling three 1/8-inch holes in the smoke-tracer case. The case is laid on a drill jig and three holes, equally spaced, are drilled into the composition, as shown in figure 34.
These holes penetrate slightly beyond the center of the loaded carton. A quick match, the end of which is first forced into the hole nearest to the center of the tracer, is now looped into two loops, the first being forced in the center hole and the second into the last hole of the tracer, the end of the match protruding a distance of about 3 inches beyond the lower extremity of the tracer.
Fig. 33. - Drilling smoke tracer.
Fig. 34. - Smoke tracer showing vents.
A small protecting pipe stem of Kraft paper, rolled in a cylindrical form, is used as a support for this match, as shown in figure 35.
Thirty-pound Kraft paper, cut 4 1/2 inches by 7 inches, is pasted around the smoke tracer and the package attached firmly to the side of the rocket-body case by a stripe of glue which is painted on the surface, the tracer abutting on the stick socket as shown in figure 37.
Fig. 85. - Smoke tracer with match assembled.
Fig. 36. - Parts of smoke tracer.
Fig. 37. - Rocket body showing smoke tracer attached.
A band 1 3/8 inches wide by 11 inches long of 30-pound Kraft paper is wrapped tightly around the rocket body and attached firmly to it, holding in place the tracer and stick socket as shown in figure 38.
The match used for igniting the propelling charge in the rocket body consists of a piece of six-ply slow match cut 6 inches long which is introduced into the orifice of the clay-bottom heading of the rocket body in the following manner:
The smoke tracer which has been attached to the rocket body has a match extending some 3 or 4 inches beyond its lower edge. The match is bent over and the end threaded through the orifice in the clay heading of the rocket body. This match is held in place while the end of the slow match used to ignite the rocket is inserted into the orifice of the clay heading. The protruding end of the slow match is laid side by side, with the match running from the smoke tracer and a small staple is driven into the interior wall of the rocket case just above the clay heading. This staple holds the two matches in position, allowing a free end to the match last mentioned, which is looped and held in position until ready for use by means of a light drumhead. The match is protected by means of a small paper tube similar to that used as a protection for the match of the smoke tracer. This protecting tube encircles only a portion of the length of the match and protects the match from abrasion caused by the staple.
Fig. 38. - Rocket body showing tends and drumhead.
Figure 39 shows the positions of the smoke-tracer match and the rocket-igniting match.
The drumhead is a piece of 30-pound Kraft paper 3 1/2 inches square, the corners of which have been clipped off 5/8 of an inch. This drumhead is given a coat of paste and smoothed down over the bottom of the rocket. When the rocket is ready to be fired this drumhead is broken and the loose end of the match is drawn out and lit.
A finishing band of 30-pound Kraft paper is cut in 8-inch lengths, 7/8 inch wide, given a coat of paste and wrapped around the drumhead. Figure 38 shows this band and drumhead.
The case is made of strawboard which comes in sheets 2G by 28 inches, 0.022 inch in thickness, Paddock strawboard being used. These sheets are cut into strips 7 1/4 inches wide by 25 inches long. The strips are placed upon a table and one edge feathered. A coating of paste similar to that used in rolling the rocket-body carton is applied to these sheets, which are in turn rolled by hand over a mandrel forming a cylinder with an inside diameter of approximately 2 inches and a length of 7 1/4 inches. The diameter of this case will permit it to be slipped over the rocket-body case.
The garniture consists of the parachute and signal, with the necessary articles for proper packing.
Fig. 39. - Cross-sectional view of completed rocket.
The parachute is made of light, tough Japanese paper. The parachute is composed of seven sectors, the length of the sector being 16 inches with an arc approximately 12 inches. These sectors are sewn together with a fine cotton or fiber thread. The parachute strings are tied to the ends of the seams. When completely assembled the parachute has a form similar to that of an open umbrella, often with an inverted cone at the center due to the drawing forward of the central parachute string which is attached to the apex of the parachute. There are eight parachute strings, seven of them extending from the seams where the sectors are sewn together and the eighth being attached to the center or focus of these seams. The strings are knotted together at a distance permitting the free opening of the parachute.
Fig. 40. - Sectional drawing of rocket head.
Fig. 41. - Parachute functioning.
Figure 41 shows a parachute which has opened up and is functioning properly, having been expelled from the case.
It is obvious that careful and delicate manipulation in packing is necessary, to insure the opening of the parachute in a proper manner so that the strings will not become entangled and prevent the proper functioning of the article. There is no standard method of folding the parachute, each manufacturer following his own plan, which according to his experience has given the best result.
The signal consists of either a white, red, or green light, a caterpillar (chain of lights), which function at night, or the smoke signal, which functions in the daylight.