Design and Performance Analysis of a Hybrid Rocket Propulsion System

Matteo Rossi^*
*Correspondence: Matteo Rossi, Department of Astronomy, University of Bologna, Via Ranzani 1, 40127 Bologna, Italy, Email:

Introduction

Hybrid rocket propulsion systems represent a promising middle ground between solid and liquid propellants, combining the safety and simplicity of solid fuels with the controllability and performance of liquid oxidizers. This unique configuration not only enhances safety and handling ease but also allows for throttling, shutdown, and restart capabilities characteristics that are typically absent in conventional solid propulsion systems. Hybrid propulsion has gained renewed interest in recent years, particularly for academic research, suborbital missions, and commercial space launch applications due to its potential for cost-effective and environmentally friendly operations. This study focuses on the design methodology and performance evaluation of a hybrid rocket propulsion system, examining propellant selection, combustion dynamics, thrust optimization, and system architecture through both experimental data and computational modeling [1].

Description

Hybrid rocket engines operate by storing the fuel in solid form and the oxidizer in liquid or gaseous form. Upon ignition, the oxidizer flows into the combustion chamber, reacts with the solid fuel grain, and generates hot gases expelled through a nozzle to produce thrust. One of the most widely used combinations in hybrid propulsion is Hydroxyl-Terminated Polybutadiene (HTPB) as the solid fuel and Nitrous Oxide (Nâ??O) or Liquid Oxygen (LOX) as the oxidizer. The selection of this pairing is driven by factors such as high regression rates, storability, low toxicity, and relatively benign environmental impact. The regression rate of the solid fuel, which influences how fast the fuel burns, is a critical parameter in the design, and it is typically enhanced through the optimization of port geometries and oxidizer mass flux.

In designing a hybrid rocket propulsion system, engineers must consider several interrelated components: the combustion chamber, oxidizer tank, injector design, nozzle configuration, and structural integrity. The combustion chamber must be thermally insulated and capable of withstanding high-pressure environments. Injector design plays a pivotal role in oxidizer atomization and distribution across the fuel surface, directly impacting combustion efficiency. Nozzle geometry must be tailored to match the expected expansion ratio to ensure optimal exhaust velocity and specific impulse. Performance simulations are often carried out using Computational Fluid Dynamics (CFD) and thermochemical models to predict combustion characteristics and to validate design assumptions before full-scale testing.

Performance analysis of a hybrid system primarily involves evaluating thrust output, specific impulse (Isp), burn time, and combustion efficiency. Experimental tests typically measure chamber pressure, oxidizer mass flow rate, and thrust curve to determine engine behavior under different conditions. Results from test firings are then compared with theoretical predictions to assess the accuracy of modeling tools and identify any discrepancies that might arise from incomplete combustion, port erosion, or heat losses. High-speed cameras and pressure sensors are also employed to study transient phenomena such as ignition delay, flame propagation, and potential combustion instabilities [2].

Conclusion

The design and performance analysis of hybrid rocket propulsion systems illustrate their viability as a safe, controllable, and adaptable alternative to traditional propulsion methods. By integrating the mechanical simplicity of solid fuels with the performance advantages of liquid oxidizers, hybrid engines address several long-standing challenges in rocket propulsion, including safety concerns, environmental impact, and cost-effectiveness. Through meticulous design processes, computational modeling, and rigorous testing, engineers can fine-tune hybrid engines to meet a wide range of aerospace applications. As research progresses and materials technology advances, hybrid propulsion is poised to play a pivotal role in the future of space accessâ??particularly in small satellite launches, reusable space systems, and educational rocketry platforms.

Acknowledgement

None.

Conflict of Interest

None.

References

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