Aircraft Wing Design Considerations - Book Report/Review Example

Aircraft Wing Design Considerations Aircraft Wing Design Considerations Introduction In aircraft wing design the most imperative considerations involves shape and size of the airplane. Designing an effective airfoil requires comprehensive understanding of how the wings work in relation to drag and lift generation. Moreover, the aforementioned understanding would be domineering in designing a conceivable and workable aircraft as explored in the paper. Q 1 Various common misconceptions exist regarding aerofoil lift amongst educationists and learners. Firstly, some argue that the inherent part of the lifting force results from effects of Newton force and other remaining part from Bernoulli Effect. It is imperative to note that the inherent explanation remains as a misconception and is entirely incorrect. Essentially, all wings that exists within a designed aerofoil irrespective of its degree of tilting, and shape normally have to create approximately 100 percent of their own lift mainly due to Newton’s resultant force. A contrary explanation would eliminate the effect of Newton and consequently, it would exist as a misconception. However, all wings normally create their own lift resultantly from Bernoulli Equation mainly due to difference in pressure across the surfaces of the wings. Secondly, some people believe in the misconception that the Newton’s laws within aerofoil relates to the inherent angle of attack while the Bernoulli Effect relates to the wing shape. The explanation is entirely incorrect since Newton’s laws relate to all features that exist within the wing that includes attack angle and shape of the wing. Similarly, in relation to Bernoulli’s effect wing shape has effect the same way angle of attack remains critical. Therefore, wings do not inherent violate neither Bernoulli equation nor Newton’s laws. Thirdly, some have the misconception that during generation of an aerofoil lift, the inherent upper parts of the foil must have more curvature compared to the lower surface. The misconception remains entirely incorrect for various reasons that define correct lifting of an aerofoil. First, the explanation remains as a misconception because most lifts can result from symmetrical airfoil in a similar manner as those applied within acrobatic aircraft. Moreover, lifts can also result from flat plywood pieces that are tilted, thin fabric airfoils, and paper airplanes (Beaty 1). Q 2 In common, explanation as aforementioned, two basic explanations exist for generation of lift by an aerofoil. The explanations includes changes in the speed of airflow in combination with Bernoulli principles and the second being Newton’s laws effects alongside downward deflection of flow. It is indispensable to note that both the above explanations explores specific aspects of generation of lift within an aerofoil but do not inherently explains other imperative phenomenon. The most comprehensive explanation of generation of lift by aerofoil entails both changes in flow speed and the aforementioned downward deflection. The explanation asserts that an aerofoil lift entails both reaction and action within the surface of the aerofoil. The action and reaction forces remains felt as difference in pressure. It is essential to comprehend that both the angle of attack and the aerofoil shape work in unison in exertion of a downward force on the flow of air that passes around the aerofoil. Based on Newton’s third law of motion, air must react by generating an upward opposite and equal force towards the aerofoil consequently resulting into generation of a lift. The inherent force that results into generation of lift results from the inherent difference in air pressure within the surfaces of the aerofoil. In normal setup, fluid pressure would always push rather than pull mainly due to its absolute positivity. Consequently, the fluid pressure exerts an inward pressure both on the lower and upper surfaces of the aerofoil. In reaction, the air flowing reduces the in existing wing’s upper surface pressure and raises that on the lower surfaces of the aerofoil as a reaction to the wing’s presence. Consequently, pressure existing on the lower parts exerts a harder upward push compared to the decreased downward pressure on the upper parts. The inherent net consequence of the forces exists as an upward lifting of the aerofoil. Q 3 a) Notably, airfoils have a unique shape with a leading edge that exists as rounded, sharp curved trailing edge, and systematically curved lower and upper surfaces. Normally subsonic aerofoil has a rounded leading edge that does not have a natural sensitivity to the inherent angle of attack. In addition, the top surface of the airfoil normally has a greater curvature compared to the bottom parts. The airfoil has a rounded leading edge to help in generation of led dragging effects and realization of more lift. The trailing edge do not disrupt airflow and a higher-pressure flowing air past an aerofoil on the lower surfaces or sides would follow a defined smooth streamline on the rounded surface and consequently spill towards the upper side on the low pressure zones within the upper surface of the wing. Shaper trailing edges would prevent the aforementioned upward spill mainly because air does not make sharp turns while in motion. Moreover, a leading rounded edge provides a possibility of smooth rejoining of airflow at the bottom and top of the airfoil. Furthermore, the leading rounded shape assists in keeping attachment of air during increase of the airfoil angle of attack (NASA Government 1). b) Normally, supercritical aerofoil has designs that give them maximum possible thickness near the leading rounded edge to assist in having more strength and length able to shock slowly the inherent supersonic flow backs that result from subsonic speeds. In most cases, airfoils that remains designed for low to medium speeds have inherently more camber and thickness in the middle. The design helps in generation of more possible lift at the lowest speed. It is essential to comprehend that the amount of thickness added above the camber line depends on the needed strength on the sings and required usual speed of the airplane at varied altitudes. c) The aerofoil has a tapered rear at the trailing edge to help smooth rejoining of airflow from the leading edge. The pressure of streamline of air flowing from the top and bottom form the leading edge needs to drop slowly at the trailing edge to enable smooth flow and balance of the airplane. Moreover, a tapered rear with less thickness also provides ability to reduce the drag effect caused by flow of air on the surfaces of the airfoil. d) The airfoil has a design of a flatter bottom to help in reduction of flow of air and consequently generation of high pressure underneath. The high pressure remains partly significant in generation of the required airplane lift. Camber relates to the curvature on the surface of an airfoil. Normally, the top surface of an airfoil has more camber than the bottom part to assist in generation of faster air flow on top of the wing compared to the underneath surface. Consequently, there would be higher air pressure at the bottom than the top resulting into lift due to the inherent difference in air pressure. Therefore, the curvature created by the camber line remains imperative in generation of lift. Moreover, a greater camber assists in giving the airplane a greater lift at very slow speeds. Q 4 It is imperative to note that any shape that can introduce a curvature within the flow-field of air can directly generate a lift (IOP Science 4). The curvature is domineering in changes the flow and direction of air to mainly asymmetric form. When the airflow direction changes, drag and lift effects acts on the object lifting it. Normally, the lift force faces a direction different from that of airflow. a) A house brick has no airfoil shape characteristics or a curvature that generate a lift. In addition, house bricks have designs with heavy materials that directly resist air movement. Significantly, the weight of the house brick directly overcomes dragging effect and consequent lift force that may result from air pressure flowing on surfaces of the brick. b) A saucer would generate lift because of the curvature on its surface that would help in creation of both the lifting and dragging effects to the flow of air. Just as a flying disc, a saucer made of light materials has a cross-sectional shape similar to that of an airfoil and would consequently generate a lift. The airfoil cross-sectional shape enables the saucer to fly by generating a lift and a spinning effect as it moves through the airflow. The lift generated by the saucer results in a similar manner as that created from traditional aerofoil through downward deflection of air. It is indispensable to comprehend that the spinning effect remains vital in movement of the saucer after its lifting. c) A football would not generate a lift mainly because it cannot create a curvature on the flow of air and consequently a disruption in the flow of air to asymmetric form. Air passing on the surface of a ball have a streams of laminar flow and only exert viscous drag. The drag only points in the direction of airflow that remains opposite to that of the relative motion of the ball. Consequently, only a spin may result and not a lift. Q 5 Drag entails the common opposition on an airplane as it moves through the air. It exists as a horizontal force that its action remains parallel to the path of flight. Drag experiences opposition from thrust effects. Drag directly results from different forces that acts in opposite directions mainly to an object’s relative motion based on the surrounding fluid that exists as air in airplane context. Ultimately, drag results from viscous friction (AV8N 1). Types of drag Drag has three main categories including wave drag, parasitic drag, and finally lift-induced drag. Parasitic drag Parasitic drag directly results from the creation airplane parts that have no direct contribution to generation of lift including the rivets, windshield and tires. Parasitic drag exists in three main significant categories including interference drag, form drag, and skin-friction drag (FAA 2). Skin-friction drag normally results from the dragging effect or resistance to the flow of air on surfaces of the airplane. In most cases, airplane designers and engineers tries to reduce skin-friction generated drag by smoothening surfaces of the plane as much as possible to significantly decrease any resultant friction. In smoothening, the designers and engineers uses waxing, smooth paints, and flush riveting technique. On the contrary, form drag directs results from resistance of the frontal surfaces of the plane to flow of air and. Normally, airplane designers reduce it through effective streamlining of the surfaces. However, interference drag directly results from airflow resistance by other airplane parts including empennage, wings, or fuselage and can significantly remain reduced through filleting. Induced drag On the contrary, to parasitic drag, that results from airplane parts that do not directly generate lift, induced drag results from surfaces of the plane that creates lift. Such airplane parts include horizontal tail surfaces and wings of the plane. In most cases, induced drag results from the direct cost of consequent lift. Normally, increasing the angle of attack directly causes a consequent increase in induced drag effect. It is imperative to note that induced drag do not rise with airplane speed but increases as the speed decreases. There exists proximal association between induced drag and difference in pressure on the surfaces of airplane wings. Normally, a decrease in speed of air flow results into airfoil producing an increase in low pressure on the upper parts of plane wings and consequent increase on the bottom parts of the wing. On the wingtip, the pressures meets causing vortex. The vortex directly results into generation of drag called induced drag that increases as the vortex generated becomes greater (FAA 4). Q 6 Boundary layer relates to the fluid layer within the bonding surface of the immediate vicinity that has significant effects of viscosity. Within an aircraft wing, the boundary layer relates to the area of flow with proximity to wing of the plane having viscous forces that directly distorts nearby flow of non-viscous air depending on Reymonds number. As air moves past airplane parts, molecules that remain near the surface sticks as those above gets slowed down. Consequently, the molecules above the surface collide constantly with the stuck molecules of the fluid. In effect, the stuck molecules directly slow movement and consequent flow of the molecules above surface of the plane. It is vital to note that as molecules moves farther from the sticking surface, collisions decreases. Such phenomenon results into creation of a thin fluid layer approximately close to the airplane part where velocity alters from zero to free stream on and away from the surface respectively. The inherent layer that exists within the boundary of the given fluids that composes of mainly air represents boundary layer as referred to by engineers (NASA Government 1). Q 7 Wingtip vortices relates to the inherent circular patterns mainly consisting of rotating air that normally remains behind airplane wing during the process of generation of lift. Each wing has a wingtip vortex trailing from its tip. The wingtip vortices remains closely associated with induced drag that result from resistance to air flow on surfaces of airplane wings. Generation of the inherent trailing wingtip vortices results when the wing directly generates an aerodynamic lift. During generation of aerodynamic lift, air that exists on the top surface of the plane has comparatively lower pressure in relation to surfaces on the bottom. Normally, air would flow from the underneath parts of the wing and come out round the wingtip and to the upper top surface within a circular motion. During the process, there would exists and emergence of circulatory flow of air in a unique pattern curling inwards, resulting into vortex. It is essential to note that the vortex remains observable from a low-pressure zone area. Normally, there exists a single wingtip vortex on the left side if the viewer stands from tail of the plane facing flight direction. Another vortex would remain visible on the right side of the wing circulating on anti-clockwise motion. Q 8 Drag Equation Drag equation relates to the formula used in calculating the drag forced an object experiences due to motion within an enclosed fluid for instance air. The formula remains accurate in only specific conditions of calculation. The conditions assert that the object has to have factor in blunt form. In addition, the fluid in question must possess an inherently adequately large Reynolds number to assist in producing turbulence at the tail of the airplane wing (NASA Government 1). Lift equation Lift equation relates to the formula of determining the amount of lift achievable under particular conditions of flow. The main significant condition in using the lift coefficient formula remains that the researcher must have specifications of the angle of attack for the wing’s lift coefficient (NASA Government 1). Q 9 a) b) Q 10 a) 2 degrees b) 11 degrees c) 2.16 degrees d) maximum lift-11 Q 11 In conclusion, designing an aircraft wing requires great understanding of the concepts behind operation of the airplane wings in relation to how they work. Shape of the aircraft wing remains essential in obtaining an effective airplane wing that would generate lift and withstand drag effects. Drag and lift effects associated with aircraft wings is imperative in its movement and only effective designs of the wings would remain successful. XFL5 software is domineering in designing an effective airplane wing that would withstand drag effects and generate smooth wings. It is imperative for engineers and aircraft designers to comprehend the misconceptions about operation of airfoils, understand XFL5 software and related applications, and finally apply the principles of designing an effective airplane wing. Bibliography AV8N. 2005. Airfoils and Airflow. December 24, 2014. Accessed from http://www.av8n.com/how/htm/airfoils.html Beaty, William. 1996. Airfoil Lifting Force Misconception. Web. December 24, 2014. Accessed from http://www.amasci.com/wing/airfoil.html#parts Federal Aviation Administration (FAA) and US Department of Transportation. 2014. Helicopter Flying Handbook: FAA-H-8083-21A. 2014. New York: /r/flying Publishing Services IOP Science. 2014. How do wings work?. Web. December 24, 2014. Accessed from http://iopscience.iop.org/0031-9120/38/6/001/pdf/pe3_6_001.pdf NASA Government. 2014. Airplane: Boundary layer. Web. December 24, 2014. Accessed from http://www.grc.nasa.gov/WWW/k-12/airplane/boundlay.html NASA Government. 2014. Airplane: Lift formula. Web. December 24, 2014. Accessed from http://www.grc.nasa.gov/WWW/k-12/WindTunnel/Activities/lift_formula.html NASA Government. 2014. Airplane: Modern Drag Equation. Web. December 24, 2014. Accessed from http://wright.nasa.gov/airplane/drageq.html NASA Government. 2014. Atmospheric Flight: The work of wings. Web. December 24, 2014. Accessed from http://quest.nasa.gov/aero/planetary/atmospheric/aerodynamiclift.html Read More