Small Rocket Research Articles

Optimizing Solid Rocket Missile Trajectories: A Hybrid Approach Using an Evolutionary Algorithm and Machine Learning

This paper introduces a novel approach for modeling and optimizing the trajectory and behavior of small solid rocket missiles. The proposed framework integrates a six-degree-of-freedom (6DoF) simulation environment experimentally tuned for accuracy, with a combination of genetic algorithms (GAs) and machine learning (ML) to enhance the performance of the missile path. In the initial phase, a GA is employed to optimize the missile’s trajectory for efficient target acquisition, defining key launch parameters such as the ramp angle and lateral maneuver force to minimize positional errors and to ensure effective target engagement. Following trajectory optimization, the derived data are used to train an ML model that predicts setup parameters, significantly reducing computational costs and time. This close integration enables real-time adjustments for acquiring moving targets, thereby improving accuracy and minimizing maneuvering costs. This study also explores the application of fluidic thrust vectoring for small rockets, providing an innovative solution to enhance maneuverability and control, especially at low speeds. The proposed framework was validated using experimental launch data from the Icarus Team. The methodology offers a robust and cost-effective solution for precision targeting and improved maneuverability in aerospace and defense contexts.

Upconverting thermal history paint for investigations of short thermal events

The main goal of the work was to develop phosphorescent coating for investigations of surface temperature distribution resulted from short duration and high energy thermal events such as small rocket engine testing. For that purpose, we developed thermal history paint with upconverting Gd2O3: Er3+, Yb3+, Mg2+ nanopowder. The developed paint was heated by Joule effect with precise control over temperature and heating time. Photoluminescence signal of cooled samples was excited with 980 nm laser and collected in automatic manner with use of an optical fibre probe connected to photospectrometer. The results show that irreversible changes of paint emission are temperature and heating time specific for calcination temperatures from 700 °C to 1150 °C. Calibration curves were prepared for heating times of 10, 60 and 180 seconds. Finally, 2D surface temperature samples were determined with use of upconverting thermal history paint and compared to IR camera and pyrometric measurements. The results indicate that uncertainty of temperature measurement below 10 °C was achieved for temperatures above 1000 °C. It has been demonstrated that developed thermal history paint allows for measurements of 2D surface temperature distribution with high spatial resolution and good agreement to standard measurements techniques like thermal camera and pyrometer.

Modeling of Spray Combustion and Heat Transfer of MMH/N2O4 in a Small Rocket Engine Using Different Mechanisms

Although various hypergolic propellants like MMH/N2O4 (monomethylhydrazine/dinitrogen tetroxide) are widely used in small rocket engines, there remains a lack of in-depth study conducted on their chemical reactions and spray combustion behaviors. To fill this research gap, a simplified chemical kinetic model that is suitable for three-dimensional simulation was proposed in this paper for MMH/N2O4. Then, numerical investigation was conducted using the Volume of Fluid (VOF) model to explore the transient injection and atomization of MMH/N2O4 impinging jets in a small bipropellant thruster. Also, the instantaneous formation and evolution of the fan-shaped liquid film were analyzed. With the spray distribution determined, the proposed kinetic model and two existing mechanisms were applied to simulate spray combustion and heat transfer within the thruster, respectively, under the Euler–Lagrange framework. According to the research results, the liquid film covered nearly the entire chamber wall with a sawtooth pattern, which protected against the high temperatures of the engine wall. Notably, the two existing mechanisms showed significant errors in predicting temperature changes around the wall due to the excessively simplified reaction pathways. In contrast, the proposed model enabled the accurate prediction of the chamber pressure, wall temperature, and thrust with an error of less than 10%. Given the high accuracy achieved by the proposed numerical method, it provides a valuable reference for the development of advanced space engines.

Research on Simulation Technology of Excitation Response of Aircraft Structural Based on Finite Element Model in Flutter Flight Test

To simulate excitation response of the aircraft structural of flutter test aircraft under different excitation methods. A simulation method for excitation response of flutter flight tests based on finite element models has been proposed. This method is based on the finite element model of the aircraft structure. Establish aerodynamic and excitation force models for flutter flight tests. Obtain a simulation model for the excitation response of aircraft flutter flight tests. Solve the model and simulate various excitation methods for flutter flight tests. Firstly, a detailed introduction was given to the excitation modeling method for aircraft flutter flight tests, including two excitation models: external excitation and control surface excitation. Then, the finite element model of the structural dynamics of a single wing with ailerons is taken as the research object. Establish a single wing flutter flight test excitation response model. Implemented simulation of control surface sweep excitation, control surface pulse excitation, and small rocket excitation. The feasibility of this method has been verified. Finally, based on the finite element model of the entire aircraft, a flutter flight test excitation response simulation model was established. We have conducted analysis and research on sensor position optimization, excitation method optimization, excitation response amplitude prediction, and flutter boundary prediction. And the simulation optimization analysis results were compared with the flight test results. Analyzed the promoting effect of flutter flight test excitation response simulation on flight tests.

Application of a Modal Parameter Identification Method Based on Variational Mode Decomposition in Flight Flutter Testing

Signals of flight flutter testing exhibit non-stationary characteristics, closely spaced modes, and low signal-to-noise ratio, presenting challenges in data processing. In recent years, the variational mode decomposition (VMD) method has emerged as a promising approach to mitigate mode mixing and exhibit robust noise resistance. Therefore, a novel time-frequency domain modal parameter identification method based on VMD is proposed to process impulse response signals in flight flutter testing. The modal frequency and damping ratio are determined through a three-step process: VMD analysis, Hilbert transform, and least square fitting. The efficacy of the proposed method in identifying closely spaced modes and resisting noise is validated through a numerical example. Furthermore, this method is applied to analyze two types of pulse excitation signals in actual flight flutter testing: one induced by the pilot’s shaking stick and the other induced by small rocket excitation. The obtained modal parameters are compared with those from ground vibration tests and specialized software, respectively, to showcase the effectiveness and superiority of the proposed method.

Mission Profile Analysis of Point-to-Point Rocket Cargo Transportation System Using Trajectory Optimization

This paper proposes new concepts for the point-to-point rocket cargo transportation system (RCTS). The RCTS is a transportation system that can deliver cargo anywhere on Earth in an hour using reusable launch vehicle technologies. As a fundamental study of global transportation on Earth, we especially address the mission profiles for short-range transportation within hundreds of kilometers using small rocket engines, which are intended for logistics transportation within neighboring countries or domestic transportation in a country. Two mission profiles of the RCTS are introduced, and the flight phases of each concept are explained in detail. The trajectory optimization problem of the RCTS is formulated based on the mission profiles, incorporating the flight constraints, boundary conditions, and an objective function that aims to maximize the payload ratio. The explicit-guidance is employed during the landing burn phase to enhance the convergence of the optimization problem by expanding the feasible region. The coevolutionary augmented Lagrangian method, one of the evolutionary algorithms, is utilized to obtain the solution for the trajectory optimization problem. The optimal trajectory and state variables are presented through numerical simulations. Additionally, parametric studies are performed to determine the payload mass trend of the RCTS. The trajectory optimization results are summarized to provide an analysis and comparison of the proposed mission profiles.

Perancangan Sistem Kanban Berbasis Web

These maneuvers use small rockets (thrusters) on the satellite body and their direction is adjusted according to the correction direction. Ignition of these small rockets will consume fuel brought by the satellite from Earth as supplies. If this supply runs out, the operational life of the satellite will end. To extend the life of the satellite, the small rockets used for north-south maneuvers will no longer be operated in order to save energy or fuel.

Death on New Year’s Eve caused by illegal fireworks—a firework shell

During the turn of the year, injuries caused by fireworks occur in Germany every year. According to the professional associations, the Unfallkrankenhaus Berlin, for example, treats an average of 50 injuries caused by fireworks on New Year’s Eve. Patients come with burns, soft tissue injuries, or fractures; eyes and hands are particularly frequently affected. Again and again, there are also very serious or even fatal injuries. The background is usually the improper or illegal use of larger fireworks. Smaller fireworks such as sparklers, bangers, or smaller rockets are available in Germany in most supermarkets, and their use is permitted from the age of 12 or 18. However, the use of larger fireworks in Germany requires proof of an official permit to handle pyrotechnic objects, which is why they are often acquired abroad. The following report describes such a case. Shortly after the turn of the year 2022, a young man died as a result of an explosive effect on the facial skull after using an illegal firework shell. The case is discussed with regard to the autopsy findings, the possible cause of the accident, and the type of firework used.

A rockoon closed helium buoyancy system; a first assessment

It is believed that the use of rockoons will revolutionize the space industry by giving priority service to microsatellite developers that now are secondary payloads for large rocket companies. However, stratospheric balloons, including rockoons, are typically filled with helium, the price of which has been rising sharply in the last decade, and if the tendency continues the use of helium in this technology could be seriously compromised. Here, we present a first assessment of the possibility for a helium closed buoyancy system in which helium is stored in a pressurized tank attached to the stratospheric balloon and pumped into the balloon and back by means of a centrifugal pump. Preliminary reckoning shows that by using a carbon-fiber-reinforced polymers (CFRP) composite as material for the storage vessel, a vessel diameter around 4.5 m will be necessary to transport a small rocket with a total mass of 150 kg. A helium closed buoyancy system will allow not just saving helium but also controlled buoyancy during lifting and the landing. Keywords: Rockoon, Helium Stratospheric Balloons, Helium Market

Experimental and Analytical Study on the Liquid Film by Jet–Wall Impingement

Liquid film cooling by jet–wall impingement on the combustor wall is commonly used in small rocket engines. The heat transfer mechanism inside the liquid film is closely related to the film flow. Therefore, we establish a comprehensive analytical model with reasonable assumptions for the liquid film flow by inclined jet–wall impingement, and we validate it through a series of experiments. It is found that the predicted liquid film dimensions agree well with the experimental results. As the impingement angle increases from 30 to 60 deg, the shape of the liquid film turns from an oval to a circle. With the increase of the impingement velocity from 7.8 to , the width, length, and area of the liquid film increase. The wall roughness ranges from 6.3 to , which shows negligible effects on the liquid film dimensions. As the surface tension increases from 36.03 to 67.13 mN/m and the viscosity increases from 1 to , the dimensions of the liquid film decrease. The effect of viscosity is more significant than surface tension within the scope of this experiment. Finally, an empirical correlation for the three investigated film dimensional parameters is proposed.

Implementasi Hasil Perancangan Sistem Pelacakan dengan Menggunakan Antena Tracking Sistem

Orbital perturbation is a phenomenon in which the orbit of a satellite changes due to one or more external influences such as an anomaly in the Earth's gravitational distribution, gravitational disturbances from the moon, meteor impacts or other objects, or solar radiation pressure. These maneuvers use small rockets (thrusters) that are on the satellite body and the direction is set according to the correction direction. Ignition of these small rockets will consume fuel brought by satellites from Earth as a provision. Communications satellites have demonstrated their capabilities since the last three decades. that the communication satellite mission in the 60s was an alternative point-to-point transmission between continents, due to its ability to see approximately one third of the earth's surface from the geostationary orbit altitude just above the equator.

Analisis Penggunaan Sistem Pelacakan Menggunakan Antena Tracking Sistem

Orbital phenomena are altered by one or more external influences, such as an anomaly in the distribution of Earth's gravity, disturbances of the gravitational pull from the moon, impacts of meteors or other objects, or solar radiation pressure. Satellites make corrections by performing maneuvers controlled by stations on Earth, these maneuvers are known as north-south corrections and west-east corrections. These maneuvers use small rockets (thrusters) that are on the satellite body and the direction is set according to the correction direction. This shift in satellite trajectory results in reduced signal quality received by stations on earth, so we have to re-pointer manually to get a better signal by shifting ajimuth, elevation, and polarization, this method requires relatively long time and a high degree of accuracy.

FLIGHT DEMONSTRATION OF A GAP/N2O DIRECT INJECTION GAS-HYBRID ROCKET SYSTEM USING A SMALL ROCKET

This paper presents the first trial of a flight demonstration experiment using a direct-injection gas-hybrid rocket (DIGHR) system, with glycidyl azide polymer (GAP) as the solid fuel and nitrous oxide (N<sub>2</sub>O) as the oxidizer. In this work, the combustion characteristics of the DIGHR system were studied. GAP is a high-energy material with characteristics such as self-decomposition, high density, and high heat of formation. N<sub>2</sub>O has high vapor pressure. Therefore, the system does not need to use additional pressurized gas to oxidize the combustion chamber. Consequently, the DIGHR system is characterized by a high-density specific impulse that enables the development of a small thruster system. In this study, a 400 N thrust class DIGHR was developed to use in the flight demonstration and a ground test was conducted before the flight test. The performance of a DIGHR system using gaseous oxygen (GOX) was previously reported, in which all of the experiments confirmed smooth ignition and stable combustion. In addition, the efficiency of the characteristic velocity (C*) decreased to approximately 85% in comparison to a system using GAP/GOX. One reason for this is that the motor sizes were different. The second reason is the use of liquid N<sub>2</sub>O as an oxidizer. However, these experimental results support the use of a small rocket at an altitude of 100 m. Therefore, a GAP/N<sub>2</sub>O flight motor was designed and developed for a small hybrid rocket. The DIGHR was launched from the ground to the sea and the experiment was successfully performed.

동일한 연소실 압력에서의 당량비 변화에 따른 기체메탄-액체산소 소형로켓엔진의 성능특성

동일한 연소실 압력에서의 당량비 변화에 따른 기체메탄-액체산소 소형로켓엔진의 성능특성

Dynamics Modeling and Characterization of Sunk Screw Connection Structure in Small Rockets

Bolted flange joints are widely used in engineering structures. Sunk screw connection structures commonly used in small rockets and missiles exhibit significant nonlinear characteristics when subjected to forces. In this article, a study of the dynamic characteristics of sunk screw connection is conducted. A 3-dof trilinear dynamic model is proposed, based on the study of the stiffness characteristics of the connection structure and considering contact nonlinearities. The connection surface is simplified as two axial trilinear springs and a lateral linear spring. The motion of the system can be divided into nine regions by the turning point of the trilinear springs. So that the motion of the system in each region can be completely resolved, the dynamic characteristics of the 3-dof trilinear system under impulse load and simple harmonic load are studied by means of semi-numerical analytical method. It is found that the response frequency of the system remains unchanged under a small impulse load, and the response can be obtained by approximate analytical expressions. When the impulse load is large, the response frequency is fluctuant, which reflects the sensitivity of the nonlinear system to the magnitude of impulse load. Under the simple harmonic excitation of bending moment, the response frequency curve of the system presents good single peak characteristics when the excitation amplitude is small. When the amplitude is large, the peak frequency of the system shifts, and the phenomenon of multi-peak resonance is shown in a certain range.

Development of a Model Rocket Trajectory Simulation Tool with Python

Within any space mission, the design of the trajectory that the spacecraft will travel across is one of the essential and most important steps. For the launch of smaller rockets, this is also a key analysis to be done during the development of the project, ensuring that the rocket achieves its flight objectives and enabling the definition of a safety radius based on its landing site. Therefore, the present work proposes the development of a tool to simulate the trajectory of small rockets that is satisfactory for use in academic projects, acting as a free alternative to similar software available on the market. For this task, the Python programming language is used, due to its open-source characteristic and shorter execution times compared to similar languages during the execution of numerical computation methods, which are necessary for modeling the rocket's flight dynamics. The results found with the use of the tool for simulating the trajectory of a model rocket are sufficient for the purpose of this work, reaching similar findings to those of simulations carried out in OpenRocket (a JAVA rocket trajectory simulation software, widely used in academic space). Moreover, a Monte Carlo simulation is performed, in which an impact point dispersion radius is estimated.

Finite Element Analysis for Rocket Motor Case Under Internal Pressure and Thermal Loads

Rocket motor combustion chamber need to contain very high pressure and temperature due to burning of rocket fuels. Although for small rocket the burning time in the combustion chamber are short about 1 to 5 seconds it is very important to make sure that the combustion chamber can hold the pressure and heat produced by the burning of the fuels. Even with a very strong material of combustion chamber and the analysis proof that the chamber is able to stand the high pressure produced there are high probability of structural failure due to the increase of temperature due to heat into the combustion chamber wall since the increasing temperature of the combustion chamber wall will decrease the strength of the material. In this study the thermal analysis was done using ANSYS software with various thickness from CC 2.5, CC 3.5 and C.C 5.0 in two condition which are the stress due to static stress and the stress due to static stress and thermal stress. The propellant properties, pressure applied, chamber temperature and heat coefficient are the same in all cases. Then the results for the different thickness stress at the wall are plotted and compared. The study shows that the results due to then static stress and overall stress with different combustion chamber thickness for the radial stress show no significant differences. While the hoop stress and von-Mises stress due to static stress are maximum at inner wall and decrease as the direction of the wall increase from the inside. In other cases where the static and thermal stress are applied, the highest stress is at the outer wall of the cylinder. The higher combustion chamber thickness, the lower hoop stress and von-Mises stress need applied to the combustion chamber wall. Thus, results in higher safety factor for the higher combustion chamber thickness.

The attitude control optimization of small rocket

In this article, an optimization method for attitude calculation and vector control of small rocket is proposed, which reduces the performance requirements and costs of gyroscopes. Dynamic model parameters such as engine thrust curve and rocket body moment of inertia are added to the traditional filtering and control algorithm, which can reduce the hardware performance requirements of sensors and the cost of rocket control system. This method has achieved good results in the test, and is of great significance for the promotion of small rockets.

On the operation of the Hanstead car

We consider the operation of the hypothetical mechanical vehicle driven by an engine powered by small rockets introduced by P D Hanstead in the inaugural volume of this journal. Hanstead arrived at three contradictory conclusions regarding the change in velocity should some of the rockets malfunction at a particular time. This thought experiment constitutes an excellent, conceptual discussion, or even exam, question for an introductory mechanics course.

초소형위성의 폐기 기동을 위한 항력 증대 장치 개발

In this paper, we described the development of a drag augmentation device for nanosatellite. Recently, space industry has entered the New Space era, and barriers to entry into Low Earth Orbit (LEO) for artificial objects such as small rockets and nanosatellite mega constellations have been significantly lowered. As a result, the number of space debris is increasing exponentially, and it is approaching as a major threat to satellite currently in operation as well as satellites to be launched in near future. To prevent this, international organizations like Inter-Agency Space Debris Coordination Committee (IADC) have been proposed space debris mitigation guidelines. The Korea Aerospace Research Institute (KARI) conducted KARI Rendezvous & Docking demonstration SATellite (KARDSAT) project, the first nanosatellites for rendezvous and docking technology demonstration in Korea, and we also developed drag augmentation device for KARDSAT Target nanosatellite that complied with the international guideline of post-mission disposal.