Question

2. A recreational airplane has a rectangular wing of constant chord c 1.0m and spanb 10m which uses the same airfoil section from tip to tip. The lift curve slope of this airfoil is shown in the figure below. It is flying at the cruising speed of 50m/s through SSL ISA conditions. Assuming no 3D (finite span) effects (we will cover these in subsequent weeks), compute the following: (a) Cruising at sea level the angle of attack of the wing is α = 3, Assuming the wing is the only surface providing lift, calculate the mass of the airplane in kg (b) Assuming fully turbulent flow, estimate the parasitic (frictional) drag on the wing in N at cruise. (c) What is the the lift to drag L/D ratio of the wing at cruise? (d) What is the minimum takeoff speed of this airplane. (e) Based on the data in the graph, write an equation for the linear portion of the lift curve in the form c-ao (a - ao) where a is in radians (and providing actual numbers for ao and ao) (f) Compare your estimate of ao with the value from thin wing theory

Answer 1

CL= 0.55 AN "ヴ,02 1.. 一.. 853,375 do Avy 50X 1 2 7 ©4857 .462 19.445

=2x s.po i '/0 do 2. 339 Taui 25 2 28. 608 m/s.. .