International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 03 Issue: 01 | Jan-2016 www.irjet.net p-ISSN: 2395-0072 © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 662 ESTIMATION OF BASE DRAG ON SUPERSONIC CRUISE MISSILE Variganji Sanjeev Kumar 1 1 PG Student, Department of Aerospace, Marri Laxman Reddy Inst of Tech & Mang, Hyderabad, Telangana, India 2 Associate Professor, Department of Aerospace, Marri Laxam Reddy Inst of Tech & Mang, Hyderabad, Telangana, India. ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Drag is the main drawback for flight and cost consideration. Among several forms of drag, one usually studied category is the base drag. This paper focuses on an improved method for base pressure and drag prediction under rocket motor-on conditions called Brazzel’s drag prediction model. Also, a major modification done in this method is, to extend its range of applicability to high values of thrust coefficient(Ct) and to Mach number less than 1.5(transonic) at zero angel-of-attack. Simulating the problem using CFD analysis, which best describes the physics behind the flow is done. For numerically predicting the base drag, codes are generated for the classical ȋBrazzel’sȌ model and modified model to validate the results. The results are compared and were found to be synonymous with each other. It can be noted that the improved method will prove to be a better and faster method in determining the base drag of a cruise missile at supersonic mach numbers. Key Words: Drag, Aerodynamic forces, Mach number. 1. INTRODUCTION Accurate prediction of drag is very important from aerodynamic configuration design point view. Initial off- prediction can lead to oversize or undersize propulsion system and intern it will affect the flying vehicle performance. It may increase the weight or may reduce the range. An initial accurate prediction of drag brings down the design time and leads to optimum configuration design. Especially, in the case of cruise missile, it is essential to predict the drag component. Prediction of power-on base drag is very critical part of overall drag. For proper and accurate design, it is important to bring out the power on base drag component for given geometry, propulsion unit and trajectory. With above as objective, a project has been carried out to estimate the power-on base drag using multiple methods. Based on literature survey, a method is selected which reasonably predicts the base drag component in power-on condition. Based on given methodology, a computer code has been developed and used for evaluating the power-on base drag for given geometry, flight conditions. 2. EQUATION USED 3. DRAG CLASSIFICATION Drag force is the summation of all forces that resist against aircraft motion. The calculation of the drag of a complete aircraft is a difficult and challenging task, even for the simplest configurations. We will consider the separate sources of drag that contribute to the total drag of an aircraft. The variation of drag force as a function of airspeed looks like a graph of parabola. This indicates that the drag initially reduces with airspeed, and then increases as the airspeed increases. It demonstrates that there are some parameters that will decrease drag as the velocity increases; and there are some other parameters that will increase drag as the velocity increases. This observation shows us a nice direction for drag classification. Although the drag and the drag coefficient can be expressed in a number of ways, for reasons of simplicity and clarity, the parabolic drag polar will be used in all main analyses. Different references and textbooks use different terminology, so it may confuse students and engineers. In this section, a list of definitions of various types of drag is presented, and then a classification of all of these drag forces is described.