Consequently, the backwards tilt of the reaction force is smaller, resulting in less induced drag for the same lift. This backwards component is induced drag! The wider the wing is, the more air can be used for lift creation, hence less deflection is needed. This means the reaction force is pointing up- and slightly backwards. This happens gradually over the wing's chord, and creates a reaction force orthogonally to the local speed of air. The wing creates lift by deflecting air downwards. What is induced drag? It is the consequence of creating lift over a limited span. However, wing span and aspect ratio will also drive wing structural mass, so you need to find a sound compromise between low induced drag and low wing mass. The ratio of wing span to aircraft mass (called span loading) is the driving force for induced drag. This means that the wing creates more lift for a given angle of attack, but also that the stall angle of attack is lower. The higher the aspect ratio, the less the wing tips will influence the airflow around the wing. Now I will focus on aspect ratio, because Jan has already answered the rest with his excellent answer. Take-off, maximum altitude and minimum turn radius are the classics which drive minimum wing area. To be more precise, he tries to set a certain wing loading, trying to minimize wing area (and weight) such that the wing creates just enough lift for the estimated aircraft mass in all design cases. Mach 3 spy plane, etc.)?ĭuring design, chord length will be the result of wing span and wing area, because those two are what the designer wants to set. Are there other factors centered on the chord length that should be considered when designing a wing? And do those factors change depending on the mission of the craft in consideration (eg., trainer v. Lastly, this all relates to how chord length is considered during wing design. Secondly, why does increasing the chord length decrease the stability of the wing? In my mind a longer wing would mean that the craft is more stable because the airflow is being forced into line for a longer period of time. There are a few things I am not understanding, but I think they probably relate quite heavily, so I'm going to ask them together.įirstly, what is the aspect ratio of the wing? Is that a reference to the incidence of the wing and how a longer wing would mean a larger percentage of the side of the fuselage is covered by the wing (as seen from the front)? Or am I way off the mark? By increasing chord, you decrease aspect ratio. If you increase the chord, lift goes up almost linearly and stabilityĭecreases, because now the wing's lift force has a longer lever arm inįlow direction. In comments on the answer to a question about transonic speeds and control surfaces I came across this comment and I'm having a hard time understanding it.
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