Surjatin Wiriadidjaja

Generic Modeling and Parametric Study of Flapping Wing Micro-Air-Vehicle

The present work is focused on the unsteady aerodynamics of bio-inspired flapping wing to produce lift and thrust for hovering and forward flight. A generic approach is followed to understand and mimic the mechanism and kinematics of ornithopter by considering the motion of a three-dimensional rigid thin wing in flapping and pitching motion, using strip theory and two-dimensional unsteady aerodynamics for idealized wing in pitching and flapping oscillations with phase lag. Parametric study is carried out to obtain the lift, drag, and thrust characteristics within a cycle for assessing the plausibility of the aerodynamic model, and for the synthesis of a Flapping Wing MAV model with simplified mechanism. Other important parameters such as flapping frequency and wing geometry are considered. Results are assessed in comparison with the existing theoretical results.

Further Development of the Kinematic and Aerodynamic Modeling and Analysis of Flapping Wing Ornithopter from Basic Principles

The basis of this work was to understand the generation of lift and thrust of a flapping bi-wing ornithopter, which is influenced by its geometrical, dynamic, kinematic and aerodynamic features by following a generic approach in order to identify and mimic the mechanisms. As further development of earlier work, three-dimensional rigid thin wing is considered in flapping and pitching motion using strip theory and two-dimensional unsteady aerodynamics for idealized wing in pitching and flapping oscillations with phase lag. Later, parametric study is carried out to attain a complete cycle’s lift and thrust physical characteristics for evaluating the plausibility of the aerodynamic model and for the synthesis of an ornithopter model with simplified mechanism. Further investigation is conducted to identify individual contribution of generic motion towards the flight forces. Results are assessed in comparison with existing theoretical and experimental results as appropriate.

Aerodynamic Interference Correction Methods Case: Subsonic Closed Wind Tunnels

The approach to problems of wall interference in wind tunnel testing is generally based on the so-called classical method, which covers the wall interference experienced by a simple small model or the neo-classical method that contains some improvements as such that it can be applied to larger models. Both methods are analytical techniques offering solutions of the subsonic potential equation of the wall interference flow field. Since an accurate description of wind tunnel test data is only possible if the wall interference phenomena are fully understood, uncounted subsequent efforts have been spent by many researchers to improve the limitation of the classical methods by applying new techniques and advanced methods. However, the problem of wall interference has remained a lasting concern to aerodynamicists and it continues to be a field of active research until the present. The main objective of this paper is to present an improved classical method of the wall interference assessment in rectangular subsonic wind tunnel with solid-walls.

Subsonic Wind Tunnels in Malaysia: A Review

In Malaysia, there exist wind tunnels operated by several universities and organizations. Most of them are actively used for a variety of experimental works that are needed by uncounted educational curricula and aerodynamics related researches. Lately, wind tunnels have even become increasingly accepted as one of common engineering tools in solving of unexpected and abundant wind engineering problems that are continually facing automotive industries, oil and gas companies, as well as governmental agencies and ministries. This paper is meant to present an overview of the existing wind tunnels, accompanied with information on some important technical data, and added, to a lesser extent, with complementary information about backgrounds and design philosophies. The emphasis is, however, given only to those with test section size of 1.0 square meter or larger. From the general point of view, some information about testing capabilities and trends in wind tunnel technology is also presented.

Computational Simulation for Static and Dynamic Load of Rectangular Plate in Elastic Region for Analysis of Impact Resilient Structure

Impact resilient structures are of great interest in many engineering applications varying from civil, land vehicle, aircraft and space structures, to mention a few examples. To design such structure, one has to resort fundamental principles and take into account progress in analytical and computational approaches as well as in material science and technology. With such perspective, the first objective of this work is to develop a computational algorithm to analyze flat plate as a generic structure subjected to impact loading for numerical simulation and parametric study without considering the surface impact effect. The analysis is carried out from first principles for static and dynamic analysis; the latter is based on dynamic response analysis in the elastic region. The second objective is to utilize the computational algorithm for direct numerical simulation, and as a parallel scheme, commercial off-the shelf numerical code is utilized for parametric study, optimization and synthesis. Through such analysis and numerical simulation, effort is devoted to arrive at optimum configuration in terms of loading, structural dimensions, and material properties, among others. The codes developed are validated for generic cases. Further simulations are carried out using commercial codes for some sample applications to explore impact resilient structural characteristics in the elastic region.

A Preliminary Study of Baseline Design Architecture Effects on Aircraft Redesign Risks

Aircraft redesign process normally does not start from scratch and requires a well-defined reference baseline design as the starting point for redesign changes. In general, the baseline design is often chosen based on the closeness of its existing performance capability to the driving requirement. This practice essentially presumes that such condition guarantees a minimum amount of required redesign changes, hence the least development risk. However, it is argued here in this study that such notion can be misleading because risk also depends on the type and the extent of the changes. Instead, it is believed that the existing baseline design architecture is an important element that will influence its suitability for the redesign task at hand. Through a sample aircraft redesign case study, the possible effects of existing design architecture on the redesign process is demonstrated and highlighted.

Usability Evaluation Survey for Identifying Design Issues in Civil Flight Deck

Ergonomics assessment for cockpit in civil aircraft is important as the pilots spend most of their time during flight on the seating posture imposed by its design. The improper seat design can cause discomfort and pain, which will disturb the pilots concentration in flight. From a conducted survey, it is found that there are some issues regarding the current cockpit design. This study aims to highlight potential mismatches between the current cockpit design and the ergonomic design recommendations for anthropometric dimensions and seat design, which could be the roots of the problems faced by the pilots in the cockpit.

Basic Geometries of the New Closed Circuit Wind Tunnel of the Universiti Putra Malaysia (UPM)

The existing UPM low speed wind tunnel was usually occupied by students, who carried out their final year projects or postgraduate researches, so that there was hardly free time slot for any additional testing work. Due to this reason, a new wind tunnel project has been started recently. Some basic specifications of the new tunnel have been pre-selected before the project was started, which comprised the following design decisions: a tunnel speed of 50 m/s, a test section area of 1´1 m2, and a closed circuit tunnel type. It wouldn’t be difficult to perceive that this pre-selection was made based on some of the trade-off results among the project’s options and constraints. This paper is aimed to present a simple analysis on the design of the new tunnel, focusing only on its basic geometries. Some design decisions that have been made related to its basic geometries are analyzed and reported in this paper. This analysis may be considered as a design verification of the new tunnel or even perhaps be regarded as scientific justification for its existence.

Conceptual Product Design Methodology through Functional Analysis

Due to high competitive nature of todays product market, it is essential for conceptual design architecture solution to be derived faster while still maintaining a certain level of innovation to differentiate it from other competing products. This can be a handful task for the development of complex product designs with the current geometrical-based approaches due to plethora of possible physical alternatives to be considered. The search for product design architecture solutions from its functional requirements is more effective as the functional space is comparatively smaller than the physical search space. This allows the design and development effort to be more focused and saves time and resources. With this notion, there is a driving motivation to adapt the functional approach into the conceptual design process to exploit some of its benefits. In this paper, a methodology to derive the product architecture solution from functional approach is discussed and proposed.

An Investigation on the Effect of Variable Valve Timing on Piston Engine for Lightweight Aircraft

As the Lycoming engine had failed its attempt on using variable valve timing for aircraft piston engine back in 1940s, the idea of the technology was abandoned as the turbines were then introduced in the aviation for better performance and greater power. Since piston engines produce smaller power efficiently in the low speed than turbine engines, they are presently still practically used in most of lightweight aircraft. With the use of a variable valve timing mechanism, it may help to increase the amount of air inlet and to provide more power output with lesser fuel consumption. With the use of this new valve system, improvements in the performance of automobile engines have been recorded. The indicated improvements, however, are limited to automobile engines running with high revolutions only. Engine simulation program was run in this investigation as an attempt to predict engine performances that are appropriate for lightweight aircraft.