• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.72-82
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• 2017

Nozzleless booster is one of the applicable components for integral rocket ramjet (IRR). In order to predict nozzleless solid booster performance, the simplified theoretical analysis was applied for L/D=5, 6, 7, 9, 11, and 13. Al-HTPB and Zr-HTPB propellant with a high metal content were used to increase the hardness because of the combustion gas flow effect. It was found that the trends between the simplified theoretical analysis and experiments were similar.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.58-66
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• 1997

To investigate the effect of the oxidizer mass flow rate on the fuel regression rate of the hybrid rocket, a laboratory size rocket was designed and ground fire test were carried out. Oxidizer was gaseous oxygen and HTPB was used as a fuel. Following correlation was obtained from the experiment. $\dot{r}$=$0.183G_o^{0.605}$

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.60-70
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• 2001

The study of compatible liner with ADP-505 propellant based PCP was performed. HTPB/DDl was chosen as a binder of liner in order to prohibit migration of nitroester plasticizer from propellant. The possible formulations for liner were screened by peel test of EPDM insulation/liner, propellant/liner and insulation/liner/propellant. Also, the adhesion tests including tension and shear were conducted. The adhesion of liner and propellant fumed out to be very good. The peel value was shown 1.5∼1.8 daN/cm, tensile force was 5.5∼6.0bar and shear force was 4.2∼5.0bar. In the samples of insulation/liner/propellant, they also have shown good adhesion properties. The peel, tensile and shear strength were 1.8 daN/cm, 5.0∼6.0bar and 4.5∼5.0bar, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.21-26
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• 2019

Exposure to a rapidly depressurized environment causes extinction of a burning solid propellant. Experiments have been conducted to determine the rate of depressurization required to extinguish a burning solid propellant. For this purpose, a depressurization combustor was designed and fabricated. The results of this experiment were used to determine the boundary between extinction and non-extinction of AP/HTPB solid propellants under different propellant compositions. Experimental results show that the initial and final pressures have a considerable effect on the critical depressurization rate.

• Advances in materials Research
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• v.13 no.2
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• pp.129-140
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• 2024

This study evaluates the ratio of Toluene di-isocyanate (TDI) functional group isocyanate (NCO) to the binder functional hydroxyl group (OH) in HTPB/AP/Al-based propellants on their mechanical properties, flow rate, and viscosity to determine the limitations of NCO/OH in the composition of solid propellants. The propellants consisted of hydroxyl-terminated polybutadiene (HTPB) polyurethane (PU), aluminum (Al) and tri-modal ammonium perchlorate (AP). The tri-modal AP consisted of 30% of coarse AP, 30% of medium AP, and 8% of fine AP. The ratio of NCO/OH varies from 0.73 to 0.85, with two binder percentages of 10.5% and 12%. An increase in NCO/OH ratio with 10.5% binder provided 20%, 95%, and 8 to 9% increments in UTS, modulus, and hardness, respectively. However, the propellant elongation, density, and flow rate decreased by 170%, 0.2%, and 11-12%, respectively. Viscosity increased 20% based on initial hour reading. The 12% binder provides 27%, 47%, and 5~6% an increment of UTS, modulus and hardness respectively. However, the propellant elongation, density, and flow rate decreased by 47%, 0.17% and 27%, respectively. The viscosity increased 30% based on initial hour reading. This study suggests the NCO/OH value of 0.77 and 10.5~11% binder content in propellant based on the mechanical properties, flow rate, and viscosity for better processing and pot life.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.383-386
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• 2006

Several HTPB/AP and HTPB/AP/HMX propellants were investigated experimentally for ignition characteristics in subatmospheric pressure. The threshold ignition pressure was 4psia for HTPB/AP composite propellant. The partial replacement of AP in HTPB/AP composite propellant by $5\sim15%$ of HMX, HNIW showed improvements in the threshold pressure was below 0.4psia. This appears to be due to the exothermic dissociation characteristics of HMX and HNIW at lower temperature $(\sim220^{\circ}C)$ than that of AP. The ignition substance B/KNO3 was coated thinly on the propellant surface for better ignition effect. As a result, ignition delay time of 15% was improved. NC is applied to $B/KNO_3$ ignition substance as a secondary binder and $NC-B/KNO-3$ suspension solution is coated to the propellant surface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.508-512
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• 2017

In this study, we carried out the study on the combustion characteristics of HTPB/AP propellants with Al and Zr as fuel metal in order to develop the solid propellant with high burning rate. The major combustion characteristics of propellant were investigated as measuring of the burning rate and pressure exponent, and the HTPB/AP solid propellants were prepared with introducing Butacene as burning rate catalyst for the enhancement of burning rate. The propellant with Al and Zr was demonstrated the improvement of propellant performance and combustion characteristic.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.6
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• pp.28-33
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• 2022

In this study, the curing characteristics of commonly used Hydroxyl terminated polybutadiene(HTPB)-based solid propellant according to the curing temperature and Equivalent ratio change were investigated. In addition, the effect of curing reaction according to their ratio and content in the Triphenyl bismuth(TPB), Maleic anhydride(MA) and Magnesium oxide(MgO) catalyst systems was confirmed. Finally, moisture was added for each propellant mixing process to check the effect of moisture on propellant curing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.11a
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• pp.3-8
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• 1995

An experimental investigation was conducted in order to figure out the multiple fire effects on the combustion efficiency and fuel properties of the solid fuel ramjet. Pure HTPB and metallized $B_4$C/HTPB fuel were studied. Fuel property effects were analyzed by using differential scanning calorimetry, The thermal or mechanical properties of the fuel grain were not affected and the combustion efficiency was a little increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.28-28
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• 2000

HTPB/AP/AI 추진제는 none-reinforcing filler가 다량 함유되어 있어 기계적 특성은 바인더와 고체 충진제의 계면 접착력에 따라 크게 영향을 받으며 이를 향상시키기 위해 결합제의 연구가 다수 진행되었고 추진제의 인장 변형율을 증가시키기 위해 HTPB의 관능기수에 따른 가교밀도, 경화제와 경화촉매, 가소제등 최적의 바인더조성을 위해 가능한 원료 및 함량 연구에 많은 노력을 기울여 왔다. 또한 추진제의 주원료로서 AP는 추진제의 성능 및 내탄도 관점에서 입자크기에 따른 연소특성 및 고성능을 위한 충전 분율에 대해 주로 연구되었으며 특히 Oberth와 Farris는 고체추진제 분야에서 많은 업적을 이루었다.(중략)