Instrument

## Aerodynamic Factors

Introduction This chapter outlines the factors affecting aircraft performance as a result of aerodynamics, including a review of basic aerodynamics, the atmosphere, and the effects of icing. Pilots need an understanding of these factors for a sound basis for prediction of aircraft response to control inputs, especially with regard to instrument approaches, while holding, and when operating at reduced airspeed in instrument meteorological conditions (IMC).

Review of Basic Aerodynamics

As an instrument pilot, you must understand the relationship and differences between the aircraft’s flightpath, angle of attack, and pitch attitude

The Four Forces The four basic forces acting upon an aircraft in flight are: lift, weight, thrust, and drag. The aerodynamic forces produced by the wing create lift. A byproduct of lift is induced drag. Induced drag combined with parasite drag (which is the sum of form drag, skin friction, and interference drag) produce the total drag on the aircraft. Thrust must equal total drag in order to maintain speed.

Newton’s First Law Newton’s First Law of Motion is the Law of Inertia, which states that a body in motion will remain in motion, in a straight line, unless acted upon by an outside force.

Newton’s Second Law Newton’s Second Law of Motion is the Law of Momentum, which states that a body will accelerate in the same direction as the force acting upon that body, and the acceleration will be directly proportional to the net force and inversely proportional to the mass of the body.

Newton’s Third Law Newton’s Third Law of Motion is the Law of Reaction, which states that for every action there is an equal and opposite reaction.

## Recover From Unusual Attitudes

Objective:

To recognize undesirable flight attitude and to apply appropriate controls to correct and recover the A/C.

• Factors that contribute:
• Instrument failure
• Disorientation
• Fixation

Nose-High Attitude:

• decreasing AS
• increasing ALT
• high rate climb VSI
• nose high AI

Nose-Low Attitude:

• increase AS
• loss of ALT
• high rate descent VSI
• nose down AI

Partial panel Unusual Attitude Recovery *( very important to read the instruments and confirm which one has failed before making correction)

Usually loss of Gyro instruments HI and AI:

• use TC to stop the turn
• ALT, VSI to stop descent or climb (change of direction – passing through level flight)
• AI can be used for pitch if ALT and VSI fail