There may be either a white, green, or red light composition loaded into the case, depending upon the particular color desired. These compositions will be taken up separately and discussed.
This is a mixture of -
Powdered aluminum ........................
A batch consists of first 18 pounds of barium nitrate screened through a 24-mesh sieve into a fiber tub. Then 5 pounds of powdered aluminum and 2 1/2 pounds of flake aluminum are passed through a 24-mesh sieve into the same tub and all are thoroughly mixed by hand and then screened through a 24-mesh sieve. One pint of ordinary gum water is then added, mixed, and the whole is rubbed and screened twice through a 12-mesh sieve. The case is first charged with first-fire composition and then the light composition is loaded into the case by hand with mallet and tamping tools in four separate charges so that the final compressed charge is even with the top of the case. It is allowed to dry for 24 hours before being assembled in the shell. The quantity and character of the composition are designed to burn for 30 seconds.
Fig. 143. - Method of mixing composition by hand.
This is a barium-chlorate and shellac mixture made up in the proportions of 90 per cent, barium chlorate and 10 per cent, orange shellac. It is a very simple mixture to make up and is effectively mixed by one or two screenings through a 24.-mesh sieve. The quantity of this composition is designed to burn 30 seconds.
This is composed of -
Potassium chlorate ...............
Strontium carbonate .................
It is made up in batches by mixing 75 pounds of potassium chlorate with 15 pounds of strontium carbonate and 12 pounds of orange shellac The constituents of this composition are compounded in a similar manner to the compositions described above. The usual practice, in order to insure uniformity and a homogeneous mixture, is to screen twice through a 12-mesh sieve. It will be noted that a guni mixture is used to act as a binder in compounding the white-light composition. In compounding the green-light composition and the red-light composition, powdered orange shellac is used, but no gum water.
The shellac performs two functions: one, supplying the means for a high temperature of combustion to the composition; the other, acting as a binder, due to the slightly tacky character of the powdered shellac which holds the mass together when pressed into the carton. This composition is designed to burn between 30 and 35 seconds.
This is comprised of two pieces of two-ply match 1 1/2 inches long. Each piece is inserted through a separate hole in the bottom disk so as to cross and leave 1 inch of the match exposed outside of the case. The junction of the matches is primed with a small quantity of prime. Figure 145 shows the quick match placed in position and Figure 146 shows it sealed by means of the prime.
This consists of a black hardware-paper disk 1 5/8 inches in diameter through which a tie cord passes. The tie cord is held to the top disk by being knotted on the inner side of the disk.
This is a paper strip 1 1/2 by 6 inches, of 20-pound Kraft paper, pasted around the case and over the edge of the top disk to hold the disk firmly in place.
Fig. 144. - Hand loading of light case.
This tie cord is used to attach the strings of the parachute to the light case and is of cotton 1/16 of an inch in diameter and 24 inches long.
The wad, which is used to prevent the flame of the expelling charge from burning the parachute and parachute strings, is made of 50-pound strawboard, cut 1 3/4 inches in diameter, with a central hole large enough to permit the threading of the tie cord through it. The string is then knotted to prevent the wad from riding.
Fig. 145. - Position of quick match on light case.
Fig. 146. - Quick match sealed with prime.
In order to prevent the flame of the expelling charge from burning the cord which holds the light suspended from the parachute, an asbestos cord is used as an auxiliary. This is tied firmly to the cord and spans the distance between the wad and the point at which the strings of the parachute are attached. The length of this cord is shown in figure 147.
Fig. 147. - Asbestos cord and protecting wad.
This figure shows also the parachute folded on the table ready to be inserted in the case.