Flight Path Flight velocity AOA AOI RAF

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Fig 1

What is flight path?
The curve which we attain by tracing Center of gravity( C.G.) of airplane at every second is known as Flight path.

What is flight velocity?
The tangent drawn to the flight path at any instant gives flight velocity.

What is Relative Air flow?
When aircraft moves, atmosphere stays rest. But in our dynamics approach in order to make analysis simple, we are considering aircraft to be stationary and the air as moving. So whatever the flight velocity with which we move, we will feel that much velocity against to that; that velocity is what Relative air flow velocity or free stream velocity.
What is angle of attack?

The angle between relative air flow and the chord line of aerofoil is the angle of attack.

Fig 2


What is angle of incidence?

The angle between fuselage reference line and average chord of wing is the angle of incidence. see fig. 1 for reference. you just draw chord line for the main wing aerofoil. Note that it makes an angle with fuselage reference line.

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