ADS T3 MV - Col·lecció Activitats dirigides Tema 3 Mecànica de Vol PDF

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Col·lecció Activitats dirigides Tema 3 Mecànica de Vol...

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` MECANICA DE VOL TURBOJETS

1 Turbojet - Stationary cruise manoeuvre Let’s consider the following information on a given acrobatic single-engine turbojet performing cruise manoeuvres: • Its parabolic drag polar can be described with the following coefficients: CD0 = 2.2 · 10−2 and k = 1.5 · 10−2 • Due to the fact of being an acrobatic aeroplane, the aerofoil is symmetric, and the next expression can be used for CL : CL = 7.1 · 10−2 · α (where α is expressed in degrees). This expression can be used up to a maximum value of α equal to 32◦ • The aeroplane total mass is 1750 kg. This mass can be considered constant along the exercise • The wing area is S=24 m2 • The gravity must be assumed as a constant, equal to g0 = 9.81 m/s2 • The atmospheric density can be estimated as a function of the altitude by means of the following expression: ρ = ρ0 · exp(−Zh), where ρ0 = 1.225 kg/m3 is the density at sea level, Z = 1.2 · 10−4 m−1 and h is the altitude. • The flight must be assumed as a symmetric one along the exercise. The Thrust’s angle of attack can be neglected. • For this turbojet, assume T11,max = 2950 N and x = 0.7 (value in the troposphere). You are asked to compute: 1. VB0 and VS0 (Base and Stall velocities at sea level). VB and VS at 8 km 2. Tmax and Tˆmax at 8 km, and Tˆ11,max 3. V1 and V2 at 8 km when T = Tmax . The values of α1 and α2 (corresponding to the two previous velocities). What is the value of Vmax at that altitude? Is it possible to flight at V2 ? 4. hT 5. Vmax,max 6. Time required to travel a distance of 9000 km at Vmax,max without wind, with a wind equal to Vw = −22 · ih m/s and finally with a wind Vw = 22 · ih m/s.

` MECANICA DE VOL TURBOJETS

1 Turbojet - Stationary cruise manoeuvre 1. 31.1, 22.7, 50.2, 36.6 m/s 2. 3795.5 N, 6.09, 4.73 3. 174.5, 14.4 m/s. 1.41, 206.2◦ 4. 23948 m 5. 183.7 m/s 6. 13.6, 15.5, 12.2 h...