This document provides three problems related to aircraft stability and control. The first problem provides numerical data about an aircraft's wing and tail and asks to calculate the neutral point location and required wing angle of attack for pitch balance. The second problem provides additional data on an aircraft and asks questions about calculating its neutral point, static margin, stability, and trimmed lift coefficient and speed. The third problem asks to calculate the tail lift and aircraft weight given information about the wing and tail lift and moments, along with the aircraft geometry and an assumption about thrust and drag locations.
This document provides three problems related to aircraft stability and control. The first problem provides numerical data about an aircraft's wing and tail and asks to calculate the neutral point location and required wing angle of attack for pitch balance. The second problem provides additional data on an aircraft and asks questions about calculating its neutral point, static margin, stability, and trimmed lift coefficient and speed. The third problem asks to calculate the tail lift and aircraft weight given information about the wing and tail lift and moments, along with the aircraft geometry and an assumption about thrust and drag locations.
This document provides three problems related to aircraft stability and control. The first problem provides numerical data about an aircraft's wing and tail and asks to calculate the neutral point location and required wing angle of attack for pitch balance. The second problem provides additional data on an aircraft and asks questions about calculating its neutral point, static margin, stability, and trimmed lift coefficient and speed. The third problem asks to calculate the tail lift and aircraft weight given information about the wing and tail lift and moments, along with the aircraft geometry and an assumption about thrust and drag locations.
This document provides three problems related to aircraft stability and control. The first problem provides numerical data about an aircraft's wing and tail and asks to calculate the neutral point location and required wing angle of attack for pitch balance. The second problem provides additional data on an aircraft and asks questions about calculating its neutral point, static margin, stability, and trimmed lift coefficient and speed. The third problem asks to calculate the tail lift and aircraft weight given information about the wing and tail lift and moments, along with the aircraft geometry and an assumption about thrust and drag locations.
1. A subsonic aircraft has a tapered, untwisted sweptback wing with straight leading and trailing edges. The tail uses a symmetric airfoil with no local moment about its own aerodynamic center. The narrow fuselage may be neglected in the consideration of total lift and moment and the engine thrust is aligned through the mass center. The following numerical data is supplied. Wing area : S = 253 m 2
Wing mean aerodynamic center : c = 5.87 m Wing mean aerodynamic center : x ac = 5.5 m (back from wing apex) Tail area : S t = 70 m 2
Tail ac location : t l = 16.75 m (back from wing ac) Wing lift-curve slope : a w = 4.2 (C L /rad) Wing local moment coefficient w ac m C = -0.025 Tail lift curve slope : a t = 4.0 (C L /rad) Tail incidence angle : i t = 2.0 o (down from wing ZLL) Downwash angle at zero wing angle-of-attack : ! 0 = 0.5 o
Downwash angle change with angle-of-attack : !" = 0.25 (rad/rad) Static margin for typical cruise flight : (h n - h) = 0.06 a. Calculate the (elevator-fixed) neutral point location with respect to the wing apex. b. Calculate the wing angle-of-attack (from the wing ZLL) required to hold the aircraft in pitch balance with zero elevator deflection.
2. An aircraft has the following data: The center of gravity is located 0.45c behind the leading edge of the wing, the aerodynamic center of the wing-body is at 0.25c, the tail volume ratio is 0.4, the wing lift curve slope is 0.08/deg, the tail lift curve slope is 0.07/deg and #!/#" = 0.3, the tail setting angle is 3 o , C Ma.c. = -0.05, and the downwash angle at zero lift is zero. The weight is 2500 lbs, the wing area is 200 ft 2 and the aircraft is flying at sea level conditions. a. Calculate the neutral point. b. Calculate the static margin. c. Is this aircraft stable? d. Calculate C M ! , C M o , and ! e
e. What is this aircrafts trimmed lift coefficient? f. What is this aircrafts trim speed?
3. A conventional aircraft (tail to the rear), is in trimmed, level, unaccelerated flight. The wing is generating 40,000 lbs of lift and has a moment around the aerodynamic center of - 20,000 ft-lb. The aerodynamic center of the wing is located at 0.25c, the center of gravity is located at 0.45c, the aircraft has a chord of 5 ft, and the symmetric tail aerodynamic center is located 10 ft behind the center of gravity. What is the lift generated by the tail and what is the weight of the aircraft? {Hint: Draw a sketch and assume thrust and all drag forces act through the center of gravity.