Lifting charge

Bottom disc Return match Gunpowder lifting charge... 

Initially the main piped match fuse is lit and a fraction of a second later the flame from this fuse reaches the gunpowder lift charge in the bag at the base of the shell. 

Therefore, the pressure-time curve for the combustion of the gunpowder lifting charge will be approximately as illustrated in Figure 4.5. 

Figure 4.5 Approximate pressure-time curve for combustion of lifting charge within a mortar tube.

The gunpowder lifting charge beneath a shell provides a source of chemical energy, a proportion of which, depending on the efficiency of the mortar, is converted into kinetic energy in the shell. 

In the case of a 75 mm star shell, fired by a 13 g lifting charge to give a muzzle velocity of 105 ms as listed in Table 4.3, the kinetic energy (KE) of the shell is given by equation (4.20). 

Obviously, with no lifting charge and fewer compartments, the mine is a little simpler in construction than the shell, but the range of effects is equally varied and interesting and includes comets, stars, whistlers, hummers, fountains and serpents. 

Sometimes we see the sparkling of a fire ball caused by burnt quick match. When shells are fired one by one in the same mortar, sometimes an unexpected explosion occurs when a lifting charge is loaded into the mortar. This may be caused by the remaining fire in the mortar which is activated a little v/hile by the Senko-PIanabi reaction. Accordingly, we must scrub the inside of the mortar and check it before loading to see if the fire spot remains in it or not ... 

To ignite the propellant charge, or as some say the Lifting charge", we use a cut star about x 3 x 30mm in size, called Sindoro" ... 

The shells are prepared in the form in Fig.1 7(A). A quick firing shell is filled with a lifting charge over the fuse and has a handle on the upper part. 

The mortar for quick firing is rather larger than an ordinary mortar in diameter to avoid a shell sticking on the way down the mortar cinder from the lifting charge is liable to collect on the inside wall. After one series has been fired, the mortar is taken off the support and the mortar is placed upside down and the igniting metal is then taken out. The inside of the mortar is carefully swept for the next firing. 

The shells for quick firing are more dangerous than ordinary shells, because the lifting charge is attached to each of the skells and can ignite from ven quite a small heat source like a small number of sparks. 

The point has been made that mortars must be swept after each shot in ordinary shooting, and after each series of shots in quick shooting with a stick attached by a piece of cloth inside the wall. This is to remove the cinder from the lifting charge and to allow the shell to be loaded easily. It is also important to remove the remaining fire which occurs due to the Senko-Hanabi phenomenon in the cinder. After the display is finished wash the mortars with water, especially the inside, and dry them well. When they are completely dry they are biledl The cinder from... 

Bottom explosion. (See "No lift.) This is an accident where a shell explodes in the mortar without ascending. This generally occurs when the lifting charge is missed and the igniter, a Sindoro, is thrown into the mortar. If it is a report shell or chrysanthemum the mortar is broken into pieces, and it is quite dangerous. However if it is a quick firing shell such an accident does not occur. 

The altitude at which the explosion of a firework shell takes place depends on various conditions i.e. the amount of lifting charge, the weight of the shell, the length and diameter of the mortar, the clearance between the shell and the wall of the mortar, the loaded state of the mortar, the length of the main fuse of the shell etc. These conditions affect each other, and the relations between the conditions are very... 

Kind of shell (inch) Weight of lifting charge (g) Altitude of explosion (ra) Diameter of chrysanthemum (m) V. eight of shell (g)... 

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