Propelan pepejal untuk kegunaan roket berbahan dorong pepejal yang telah dihasilkan di Universiti Teknologi Malaysia (UTM) adalah dari kumpulan propelan komposit kalium nitrat sebagai pengoksida dan sukros sebagai bahan api. Antara kaedah fabrikasi propelan adalah teknik pembentukan (forming), penyemperitan (extrusion), tuangan (casting) dan pengacuanan mampat (compressed moulding). Semua kaedah ini telah menghasilkan pelbagai propelan dengan sifat serta gaya laku yang berbeza–beza.
Bergantung kepada bagaimana ia difabrikasi, propelan ini telah menunjukkan perkaitan sifat mekanikal yang begitu ketara. Dari setiap kaedah, propelan dibentuk mengikut satu bentuk serta dimensi yang piawai. Ujian kadar pembakaran dibuat ke atas setiap jalur propelan menggunakan alat uji kaji (test rig) yang telah direka bentuk. Ujian kadar pembakaran dilakukan pada tekanan atmosfera. Melalui ujian ini, kadar pembakaran propelan telah diperolehi. Hasil uji kaji menunjukkan kadar pembakaran propelan yang menggunakan teknik pembentukan dan teknik pengacuanan mampat masing–masing adalah 1.033 cm/s dan 0.429 cm/s. Manakala kaedah penyemperitan dan kaedah tuangan didapati tidak sesuai kerana sifat propelan kalium nitrat–sukros yang likat. Hasil uji kaji menunjukkan kaedah pengacuanan mampat ialah kaedah yang paling sesuai berbanding kaedah yang lain kerana dapat menghasilkan propelan yang seragam dan stabil.
Kata kunci: Propelan; komposit; pengoksida; bahan api; kadar pembakaran
Solid propellant used on solid fuel rocket developed at Universiti Teknologi Malaysia (UTM) is from the composite propellant group with potassium nitrate as the oxidizer and sucrose as the fuel. Among the propellant fabrication techniques are forming, extrusion, casting and compressed moulding. All of these techniques are used to fabricate several types of propellant with different characteristics and performances.
Depending upon the technique of fabrication, these propellants have shown strong relationship with their mechanical properties. With every technique, the propellants are formed according to a standard shape and dimension. Burning rate tests were performed for each propellant strand fabricated using the test rig designed. The burning rate tests were performed at atmospheric pressure. Through this test, the propellant burning rates were obtained. Experimental results show that the burning rate for propellant developed using forming and compressed moulding are 1.033 cm/s and 0.429 cm/s, respectively. Meanwhile, the extrusion and casting methods were found not suitable due to the property of potassium nitrate–sucrose that is viscous. Experimental results show that the pressed moulding method is the most suitable method compared to the other techniques since it can produce propellant that is uniform and stable.
Key words: Propellant; composite; oxidizer; fuel; burning rates
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