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SECTION B Question 4 (25 marks) An F-16 Daircraft is not properly trimmed for takeoff, because its rudder trim tab is inadvertently set to maximum right deflection (12º right). The aircraft takes off (Weight Off Wheels-WOW point, Figure 4.2) and it crashes 6 seconds later (impact point, Figure 4.2). The powerplant settings stayed at maximum afterburner throughout the 6 seconds. The forces applied to the control stick by the pilot were constantly left and aft, up to the maximum values possible (ie stick in the lower left corner). The position of the control stick (bottom right hand side of the Figure 4.1) of the F. 16 D is shown in Figure 4.1 below I Figure 4.1 At the 'Weight Off Wheels' point (Figure 4.2), the following data is recorded by the flight data recorder of the aircraft: AOA 4.75 Pitch 7 degrees (nose up) Roll-1.4 degrees (left wing down) Pitch stick 12 lb. (aft) Roll stick - 12.5 lb. (left) Left Flap 6 Right Flap 20 Rudder -7.0 (right) At the impact point (Figure 4.2), the following data is recorded by the flight data recorder of the aircraft: AOA 17 23 Pitch -7.0 Roll 73.1 degrees (right) Left Flaperon - Right Flaperon -20 Page 9 of 11
The above mentioned points and the flight trajectory of the aircraft can be seen in Figure 4.2 below: Ramp E2 Shelter D-4 Impact point Weight off wheels "leak check area Figure 4.2 A 3-view image of the aircraft type is provided below in Figure 4.3 as well: Figure 4.3 a) Develop a possible scenario explaining why and how the aircraft ended up crashing, from an aircraft stability point of view. (20 marks) b) Explain how different control inputs, applied by the pilot, would have recovered and stabilized the aircraft, thus avoiding the crash. (5 marks)