Indonesian Journal of Aerospace

Stability Analysis of 3D UAV Gimbal using Flexible Body

Neno Ruseno — 2023-06-30

Unmanned aerial vehicle (UAV) application in visual object tracking requires a gimbal to stabilize the camera in following the object’s movement. External disturbance and gimbal stability are the issues in this application. This study aims to analyze disturbance effects and study the stress and modal analysis on UAV gimbal using flexible body concepts. The three-dimensional (3D) gimbal is modeled using the RecurDyn software consisting of 3 arms and a camera. Each of the arms is connected using a revolute joint and a rotational force to represent a motor. The considered disturbances are step, pulse, ramp, and sine wave input. The PID controller is used to stabilize the gimbal arm from the gravity of the camera and external disturbance. The result shows that the PID controller is robust to step, pulse, and ramp disturbance, but not to the sin wave disturbance. In addition, the second arm of the gimbal is the most stressed component and is prone to vibration.

Automatic Gain Control for UAV Stability Augmented System Using Jacobian Method

Prasetyo Ardi Probo Suseno — 2023-06-30

A flight control system is an important system in aircraft to direct the aircraft and maintain the aircraft’s attitudes. One of the most important parts of the flight system is the stability augmented system designed to improve the stability of the aircraft during flight. This system is usually located as the most inner-loop part of the flight control system. There are many methods to design gain control feedback for aircraft stability systems. In this paper, the longitudinal stability augmented system for Unmanned Aerial Vehicle Albatross is designed using the Jacobian methods. The Jacobian method is capable to generate feedback value automatically within the limitation given by design requirements and objectives. This method allows a faster design for the stability augmented system on multi-trim points compared to the classical method such as PID tuning. The results that the designed system works well and conforms with the design requirements and objectives.

Integrated Numerical Investigation on the Aerodynamics Characteristic and Vortex Development of Airfoil using Spalart-Allmaras Model

Okto Dinaryanto — 2023-06-30

In this paper, the numerical simulation successfully obtained good results in analyzing fluid flow over the airfoil. Detailed explanations of simulation steps were also presented. The flow characteristics over three airfoil models were numerically simulated in this work: NACA0021, NACA2409, NACA2409+Fowler flap. The reliable Spalart-Allmaras (S-A) turbulent model was used and validated using reported data from experimental in terms of lift and drag coefficients. In this regard, the discrepancies of less than 10% were obtained for both coefficients, respectively. The boundary layer separation, vortex development, and air separation were clearly captured. The results of symmetric airfoil showed that the vortex shedding regimes occurred at α = 8^o, and the stall critical-angle was about 14^o. The value was higher for the NACA2409, where the airflow exhibited a relatively more stable behavior. Moreover, it is evident that flap addition altered lift-drag characteristics. The value of the lift-to-drag ratio increased due to the increase of C_l and the reduction of C_d. The parametric study was done on the α and flap deflection angle to attain the desirable airfoil configuration. The maximum result of airfoil configuration was obtained on the NACA2409 at α = 12^o with 10⁰ flap deflection angle while it enhanced the lift coefficient by about 54%. This result strengthens the robustness of the S-A turbulence model and projects the use of the S-A model for dealing with the aerodynamics analysis. This study is beneficial for initial aircraft design on the aerodynamics aspect of a wing.

A Comparison of Vacuum Infusion, Vacuum Bagging, and Hand Lay-Up Process on The Compressive and Shear Properties of GFRP Materials

Kosim Abdurohman — 2023-06-30

Fiber-reinforced plastics are widely used in aerospace, marine, military, automotive, wind turbine, sports, and civil engineering applications. GFRP is a common material used in engineering applications such as for UAV structural material. Several techniques that can be used in the composite structure manufacturing process are HLU, VB, and, VARI. This paper studies the influence of the three manufacturing processes on the compressive and shear properties of GFRP composites. This study uses e-glass fiber as reinforcement material and a clear epoxy polymer called lycal as matrix material. The composites were manufactured by using HLU, VB, and VARI processes. The specimen dimensions, compressive, and shear tests are following ASTM standards. The microstructural characteristics were observed using a scanning electron microscope. The compressive strength of VARI composite is higher than HLU and VB composites up to 71% and 53%, respectively. The shear strength of the VARI composite is higher than HLU and VB composites up to 71% and 53%, respectively.

Impact Point Dispersion Prediction for 300 mm R-Han 300 Artillery Rocket

Ahmad Riyadl — 2023-11-24

The effectiveness of artillery rocket in battlefield is the determined by its impact point dispersion, which may occur due to manufacturing and measurement inaccuracy, initial launch perturbations and atmospheric conditions. Therefore, the objective of this study is to establish model that could predict the impact point dispersion of R-Han 300 rocket using Monte Carlo method. Generic rocket of 6 Degree-of-Freedom model was implemented to investigate the impact point. Initially two simulations with 1000 iterations were carried out, first to study the effect of value uncertainty of every parameter on the impact point dispersion at launch elevation angle 50 degrees, second to study the impact point dispersion caused by value uncertainty of all the parameters at launch elevation angles ranging from 30 to 70 degrees. The second simulation is then repeated with 10000 iterations. This study showed that the dispersion increases as the launch elevation angle increases, except around the optimal launch elevation angle that give the farthest range. Monte Carlo simulation with 10000 iterations showed a better normal distributed data then the simulation with 1000 iterations, but the maximum difference in value of CEP resulted from both simulations is very small, which is 3.16%.