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Velocity Model 2

Velocity Model

Q You are flying a DA20 and are getting ready to land. Your current approach speed is 106 km/h and a tower reported cross wind (i.e. provides an added velocity) of 15 km/h at an angle of 90° to the runway. At what angle (crab angle) should you orient the plane to the runway so that you will approach in a straight line? Do you think this is within safe limits or would you be advised to go around from a landing? Also consider the case that the same crosswind speed were to blow from a non perpendicular direction. How, if at all, would this change your answer? Rubric Modeling Modeling Criteria Ratings Pts This criterion is linked to a Learning OutcomeAccuracy All the ideas used in the diagram and/or narrative correspond to ideas established by the class thus far. (No ideas are used that have not been previously established and agreed on.) 5 pts This criterion is linked to a Learning OutcomeCompleteness All the established ideas and assumptions necessary to explain the event are included in the diagram and/or narrative. (No relevant ideas are missing.) 5 pts This criterion is linked to a Learning OutcomeClarity and Logical Reasoning The presentation is well done so that it flows logically and is easy to follow. It also explicitly connects the relevant ideas to the event being explained. 5 pts Total Points: 15 PreviousNext

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To orient the plane so it approaches the runway in a straight line, I should align the plane's velocity vector with its centerline. To do this, I will apply a crab angle to the plane to counteract the crosswind effect. The crab angle is calculated by taking the angle of the crosswind velocity vector (15 km/h at 90° to the runway) and subtracting it from the approach angle of the plane (106 km/h). In this case, the crab angle would be: Crab Angle = 90° - atan(15/106) The angle of the crosswind velocity vector (15 km/h at 90° to the runway) is perpendicular to the runway, so the crab angle would be very small, it will be close to 0°