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18 KiB
Plaintext
1 line
18 KiB
Plaintext
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Originally Displayed on P-80 Systems
From "The Chemistry of Powder & Explosives by Tenney L. Davis" 1943.
The principle of the rocket and the details of its design were worked out at an early date. Improvements have been in the methods of manufacture and in the development of more brilliant and more spectacular devices to load in the rocket head for display purposes. When rockets are made by hand, the paper casing is mounted on a spindle shaped to form the long conical cavity on the surface of which the propelling charge will start to burn. The composition is rammed into the space surrounding the spindle by means of perforated ram rods or drifts pounded by a mallet. The base of the rocket is no longer choked by crimping, but is choked by a perforated plug of clay. The clay, dried from water and moistened lightly with crankcase oil, is pounded or pressed into place, and forms a hard and stable mass. The tubular paper cases of rockets, gerbs, etc., are now often made by machinery, and the compositions are loaded into them automatically or semi-automatically and pressed by hydraulic presses.
John Bate and Hanzelet understood that the heavier rockets require compositions which burn more slowly.
"It is necessary to have compositions according to the greatness or the littleness of the rockets, for that which is proper for the little ones is too violent for the large--because the fire, being lighted in a large tube, lights a composition of great amplitude, and burns a great quantity of material, and no geometric proportionality applies."
Present practice is illustrated by the specifications tabulated below for 1-ounce, 3-ounce, and 6-pound rockets as now manufactured by an American fireworks company.
Ounce Ounce Pound
Size.................................... 1 3 6
Saltpeter....... 36 35 30
Sulfur.......... 6 5 5
(Composition of charge) No. 3 charcoal.. .. 5 5
No. 5 charcoal.. 12 .. ..
Charcoal dust... 7 17 12
Inch Inch Inch
Length of case........................ 3 4 1/4 13
Outside diameter...................... 1/2 11/16 2 3/8
Inside diameter....................... 5/16 7/16 1 1/2
Overall length of spindle............. 2 3/4 4 12 3/4
Length of taper....................... 2 1/2 3 23/32 12
Choke diameter........................ 5/32 1/4 3/4
The diameter of the base of the spindle is, of course, the same as the inside diameter of the case. That of the hemispherical tip of the spindle is half the diameter of the choke, that is, half the diameter of the hole in the clay plug at the base of the rocket. The clay rings and plugs, formed into position by high pressure, actually make grooves in the inner walls of the cases, and these grooves hold them in place against the pressures which arise when the rockets are used. The propelling charge is loaded in several successive small portions by successive pressings with hydraulic presses which handle a gross of the 1-ounce or 3-ounce rockets at a time but only three of the 6-pound size. The presses exert a total pressure of 9 tons on the three spindles when the 6-pound rockets are being loaded.
Rockets of the smaller sizes, for use as toys, are closed at the top with plugs of clay and are supplied with conical paper caps. They produce the spectacle only of a trail of sparks streaking skyward. Rockets are generally equipped with sticks to give them balance and direct their flight and are then fired from a trough or frame, but other rockets have recently come on the market which are equipped with vanes and are fired from a level surface while standing in a vertical position.
Large exhibition rockets are equipped with heads which contain stars of various kinds, parachutes, crackers, serpents, and so on. In these, the clay plug which stands at the top of the rocket
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