DESIGN AND ANALYSIS OF AUTONOMOUS 400MM SPAN FIXED WING MICRO AERIAL VEHICLE M.Satyanarayana Gupta M.Venkateswar Reddy Professor and HOD, Aeronautical Department, AssociateProfessor, MLR Institute of Technology, Narasimha Reddy Engineering College, Hyderabad,T.S, INDIA Hyderabad,T.S, INDIA D.Ramana Reddy Professor & Principal, Vivekananda Institute of Technology and Science, Karimnagar, T.S, INDIA ABSTRACT: A micro air vehicle (MAV), is a class of unmanned aerial vehicles (UAV) that has a size restriction and may be autonomous. MAVs are a new class of vehicles that has sparked considerable interest in aerospace R&D recently. This papermainly discusses the design 400 mm fixed wing MAV. Due to the small size of MAVs, flying wing configuration to maximize lift. Planform is designed with procedure. Designed wing is analyzed in XFLR5 software. Aerodynamic performance is calculated to check whether it is matching with XFLR5 results. The designed model is then fabricated using dense foam by hot wire cutter. The required avionics and propulsion systems of the model are selected using the weight parameter and according to required specifications. Eagle A3 axis gyro is used to stabilize the vehicle. Nomenclature A = amplitude of oscillation a = cylinder diameter C p Cx Cy = pressure coefficient = force coefficient in the x direction = force coefficient in the y direction c = chord dt = time step Fx = X component of the resultant pressure force acting on the vehicle Fy = Y component of the resultant pressure force acting on the vehicle f, g = generic functions h = height i = time index during navigation j = waypoint index K = trailing-edge (TE) non dimensional angular deflection rate 1. INTRODUCTION 1.1. MAV s Introduction Micro Air Vehicle (MAV) is defined as a small, portable flying vehicle which is designed for performing useful work. They have the potential to revolutionize our sensing and information gathering capabilities in As the size of a vehicle becomes smaller than a few centimeters, fixed wing designs encounter fundamental challenges in lift generation and flight control. Hence, researchers are slowly arching towards bio mimicking flapping wing MAVs. They offer great potentials for various civil and 142
military applications, especially for surveillance and sensing at remote and hazardous locations. 1.2. Low Reynolds number Flow over Airfoils The performance of Airfoils operating at low relative wind speeds (low free stream velocities) has been of interest in modern subsonic aerodynamics. To characterize flows, the dimensionless Reynolds Number is used. As Reynolds number is proportional to free stream velocity, the low wind speed flows (low free stream velocity) correspond to low Reynolds numbers. At low Reynolds numbers, the Airfoils generate lesser lift, and encounter higher drags, bringing down the performance of the Airfoil. This study gives a basic overview of low Reynolds number flows and proposes methods to tackle the challenges of low lift and high drag in such flows. 2. LITERATURE REVIEW The emergence of remotely piloted vehicles for military surveillance missions during the late seventies led to an increase in research of lower Reynolds numbers aerodynamics Comprehensive literature surveys of this area of research can be found in Mueller (1985) and Lissaman (1983). Micro aerial vehicles, in contrast, operate at significantly lower speeds and have smaller dimensions; their Reynolds numbers range is approximately 150,000 or lower. In the last five years, ongoing research has revealed the dominant flight mechanisms present at these Reynolds numbers. Nevertheless, a complete analytical or theoretical procedure for predicting lowreynolds number aircraft performance is not yet available. Computational techniques are under development but they take considerable computer time as the equations that must be solved are fully viscous for such low Reynolds numbers. No other air vehicle Design space has presented the mix of challenges as that of the miniature flight platforms. The creator of these aerial robots must address the same physical design constraints which have already been mastered by the world of airborne biology.weight of aircraft 200gm, Payload capacity 50 gm, Wing loading around 20 N/m2, Cl required = 0.457, Thrust more than 500gm, Cm almost near to zero at angle of req Cl. New Use case for indoor operation, after 2 decades of UAV development, no assets exist to covertly penetrate buildings, tunnels/caves and bunkers. Size is important in indoor and confined spaces. Unfamiliar enclosures are dangerous for soldiers to enter. Ground Vehicles have difficulty penetrating. No need to operate in high difficulty penetrating. No need to operate in high winds. No need for long stand-off. 3. DESIGN METHODOLOGY Design is an iterative effort, as shown below. Requirements are set by prior design trade studies. Concepts are developed to meet requirements. Conceptual design is made to check whether it is possible to meet the requirements otherwise requirements are revised. Figure 1: Block diagram of Design Procedure Due to the small size of the MAV, the design of it is complicated when related to Conventional subsonic aircrafts. The design of this MAV is an iterative process. Key features considered aretotal weight,largest linear dimension, Flight speedhigh endurance, Stable flight. 143
The methodology for the preliminary design will be Weight Estimation, Wing Loading from the Great Flight Diagram, Minimum required area for lift, Required Lift Coefficient, MAV Aspect ratio, Platform selection, Airfoil selection, Require Angle of Attack (AoA) GCS System Features Notebook PC based system with facility for Air vehicle command &Control, for Telemetry and Video Display Link System Features Uplink and Telemetry cum Video Downlink, Link range > 2Kms Image Processing Image processing for enhancing the resolution and quality of the video images to aid detection and recognition of targets. It shall have the capability to freeze frames and video clipping. The requirement is to design a 400mm span air vehicle capable of carrying a miniaturecd DLTV camera as a payload and with an endurance of 30mins. Mission wing and is common for low-speed designs. Tapered wing is aerodynamically more efficient than straight and easy to fabricate than elliptical. AOA and CD of different planeforms are given in figre3 and 4 respectively.. AOA for rectangular planform AOA for EllipticalPlan form Figure 2: Mission profile 4. DESIGN PROCESS High lift airfoil and seen that its Clmax is 0.7933 which is less than our requirement and additionally aerodynamic efficiency is also much less. As we have only Elevon as control surface this high pitching moment will not be encountered by Elevon. Even with High Lift airfoil we could not getcl 0.5 at the cost of reduced aerodynamic efficiency and large pitching moment.this is most structurally-efficient AOA for Zimmerman Planform 144
AOA for Inverse ZimmermanPlan form Figure3: AOA for Different Plan forms Cd for rectangular Plan form Cd for Elliptical Plan form Figure 3: Cd for zimmermanplanform Cd for Inverse Zimmerman Planform Figure 4: CD For Different Planforms A short examination of these plots reveals that the Inverse Zimmerman planform offers the best shape for an MAV which is restricted by maximum dimension. For a given maximum dimension & aspect ratio, the inverse Zimmerman planform has the lowest required angle of attack (α) & also the lowest value of CD. After continue iterations we find to have 3 types of airfoils to concern about. They are High lift Airfoils like (E61,E62.E63) Low pitching moment (symmetrical Airfoils) High aerodynamic efficiency Airfoils(S5020,S5010,S4083,ClarkY) These 3 sub considerations allow us to modify our model according to the need, but the main parameter of better design evolve after many combinations and selection of airfoil with a suitable airfoil. 4.1 Model 1 The model is designed considering the geometrical consideration including the thickness parameter of the airfoil. The E61 airfoil is very thin which make it very difficult to integrate the components and avionics in it as it would be in flying configuration. To overcome that we have to design underneath the wing to carry avionics and payload in it. The dimensions of the model are described below. The designed model is then generated in Catia for better visual glance of the model and verifications of the components placements that gives the overall 145
clarity of model overview. The isometric model is shown in figure2. Figure 9: surface velocity Figure 5: Model 1 The generated model is finalized with the dimension and then generated using the dimensional coordinates in the XFLR5 software for analysis at different condition. The XFLR5 model1and dimentions are shown figure6 and 7. Figure 9: CP plot Figure 4: XFLR5 model Figure7:Wing Dimension Figure 10: Overall plots 4.2 Model 2: This model is flying wing type model as its airfoil is thick which will be sufficient to integrate the components and indeed there is no requirement to design any fuselage body for the purpose of components. Figure8:Xflr5 lift curve Figure 11:Xflr5 146
Figure 12: wing dimensions Figure13: stream line Figure 17: overall plots The model is then fabricated using high dense thermocol sheets and hot wire cutter. The airfoil templates are made out of wood using an airfoil paper plotter Xplot. Using this templates the hotwire cutter is used to trace the boundaries around the wing span keeping airfoil templates as support. Figure 14: SURFACE VELOCITY Figure15: lift curve Figure 16: Cp plot 5. CONCLUSIONS 1 An empirical methodology for the design of a MAV is discussed. 2. 400 MAV is designed by selecting the components and estimating the weight of the MAV. A suitable planform and airfoil is selected for the required weight and performance. 3. The Lift and Drag of MAV is found and an appropriate propulsion system is selected. 6. The CAD model of MAV is made in CATIA and the CG of the MAV with the components assembled in it is found. The CG was placed such that a static margin of 10.43% is maintained for longitudinal stability. 7. The fabrication drawings of the wing and the fuselage are made. 147
8. MAV model 1 is made from corrugated plastic sheets and the model 2 is made from thermocol sheets, components are assembled into the fuselage as per the required CG location and is tested in the RC mode for flight worthiness. REFERENCES 1. 1. Nieruch K. D,Operational inspection methods of fibre composite airframe structures used for maintenance, PhD thesis, April 2012 2. Calligaris A., Reparability, A350 XWB Structure CFG, 24-26 th September 2008. 3. Calligaris A., Robustness by design, A350 XWB Structure CFG, 24-26 th September 2008 4. Baker A. A., Rose L. R. F., Jones R., Advances in the Bonded Composite Repair of Metallic Aircraft, Elsevier 2002 5. K Amadori*, D Lundström, P Krus,, Automated design and fabrication of micro-air vehicles, October 19, 2011,Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 6. Torres design and fabrication Of UAV, university of Notre dame 7. Prof. C. R. L. Murthy Et. Al., Micro Intellicraft. 8. HenkTennekes, The Simple Science of Flight: From Insects to Jumbo Jets 9. Thomas J Mueller Et. Al., Introduction to the design of Fixed Wing Micro Air Vehicles: Including three case studies 10. Gabriel Torres and Thomas J. Mueller, Micro Aerial Vehicle Development: Design, Components, Fabrication, and Flight Testing 11. Thomas J Mueller, Aerodynamic Measurements at Low Reynolds Numbers for Fixed, Wing Micro-Air Vehicles, 1999 12. Mark Luke Et. Al., Predicting Drag Polar for Fixed Wing Micro Air Vehicles, AIAA 2004-6330 148