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RECOMMENDATIONS FOR SELECTION OF SELF-FUEL FUEL FOR ENGINES
MODELS OF ROCKET
Glossary of terms
Sometimes a mixture consisting of 60% nitric acid potassium KNO3 (saltpeter) and 40% sugar powder (by weight), called "caramel fuel", is sometimes used. This elementary fuel is capable of raising a small rocket (about 300 mm long ) to a height of up to 300 m , but the preparation tool is very unsafe for unlucky pyrotechnics. The difficulty lies in the fact that if both components are confused at a high temperature, then a slight overheating, as well as stirring, threatens with an explosion.
In addition, poorly crushed and mixed components dry out after drying, resulting in cracks filled with air inside the fuel. After ignition of the fuel prepared in this way, a sudden and uncontrolled multiplication of the pressure in the combustion chamber of the engine results, and it also explodes.
The use of these components in powder form excludes the risk of explosion, but requires careful preparation of the engine control, too, as if the melted sugar clogs the nozzle and often leads to the formation of cracks in the walls.
Among the many varieties of solid fuels, it is difficult to find a fully safe and at the same time high-calorie. Therefore, there is no need to conduct research in this course, much less put the experiments - this is already done by experts in return.
For amateur rocket-building, only one fuel is recommended, but it is the mixture of zinc and sulfur in the form of finely powdered powder. This fuel has already been thoroughly studied and tested. Yet it is intended for relatively large rockets - amateur as well as research rockets.
It can also be used in circles working under the guidance of instructors. A powdery zinc mishmash with sulfur forms a chemical union - zinc sulphide. The effectiveness of this fuel depends on various factors, for example such as the engine system (especially the nozzle) and even the humidity also the ambient temperature. The mixture of zinc and sulfur ignites from the electrical ignition system is also not sensitive to impact.
Dust mixture, rising in the air, acts on the mucous membrane of the nose and also the eye. Therefore, when powder is poured, it is necessary to use a dustproof mask. It should be noted that the zinc dust particle (as well as any metallic dust) in certain thermal conditions can come into contact with the atmosphere if ignited.
Therefore, when carrying the powder in impressive quantities, it is necessary to observe special care. Mix the ingredients in wooden utensils (but not in metal), rotating it, as it is working, mixing cement.
The following weight ratio is recommended: 2.04: 1.0 (zinc 2.04, sulfur 1.0) , which results from the ratio of the atomic weights of both components. The atomic weight of zinc ( Zn ) is equal to 65.38 , but sulfur ( S ) 32.07 . As a result of the chemical reaction taking place in the combustion chamber of the engine, zinc sulphide Zn + S = ZnS is formed . To fill the engine with the mentioned fuel it is necessary to use a wooden spoon in an open atmosphere or in a well-ventilated place. Due to the danger that lies in the homemade, primitive preparation of rocket fuel, specialists have also begun to develop fuels for engines, as a result of which model-based industrial engines appeared, fueled with an accurately calculated energy reserve, simple in design, also in use. However, the most proud thing is that the engine with industrial fuel alienates the missile modeler with a significantly impressive safety guarantee than the best-prepared fuel of own manufacture.