mercredi, janvier 22, 2020

Study flight

Study Before Flying

Attitudes and Movements

Attitudes and Movements

Attitude:    describes the airplane’s orientation relative to the horizon.
Movements:  are the motions, called   roll, pitch, and yaw that result in changes of attitudes.
aviation learning

Objectives of the lesson

  • Knowing the range of attitude use in normal flight.
  • Knowing the movement necessary to produce and maintain desired attitude.
  • Learn yaw and how to control it.
  • This basic principles that we need to learn, everything depends on it (climb, descent, turn, cruise attitude and straight-and-level flight).

Cruise attitude

  • It’s the REFERENCE ATTITUDE ALL OTHER ATTITUDES ARE VARIATIONS FROM THIS ATTITUDE
  • zero pitch attitude.
  • zero bank attitude.

Horizon in cruise attitude

  • The primary visual reference used is usually the appearance of the natural horizon or the ratio of visible sky to ground, when you are looking straight ahead.
  • The line of the dashboard are around three finger wide from the horizon line.
  • To maintain the cruise attitude keep the horizon at the proper location in the windscreen.
  • The wings remain parallel to the horizon.

Instruments indications in cruise attitude

The attitude of flight may be broken down in two groups:

  • Pitch attitudes: any attitudes of the nose of the aircraft above or below the reference datum (horizon). The attitudes above the datum are termed “nose up attitudes”, and those below, “nose down attitudes”.
  • Bank attitudes: any attitudes of the wings of the aircraft when inclined relative to the datum.

Pitch attitudes

   Pitching movement:
  • Are produced and controlled by the elevators.
  • This movement is used to achieve pitch attitudes.
  • These attitudes are maintained by use of elevator.
  • The elevators are controlled by the movement of the control column forward or backward.
  • Movement about the lateral axis.

Bank attitudes

Rolling movement:
  • Are produces and controlled by the ailerons.
  • This movement is used to achieve bank attitudes. (15°max)
  • Roll is simply produced by rotating the control column left or right much like rotating the steering wheel of a car.  Once the desired bank is obtained, the movement is controlled by reducing the rotation of the control column and simultaneously placing it in the neutral position.
  • Movement about the longitudinal axis.

Yaw

  • The final movement is referred to as yaw, and unlike pitch and roll, it is usually an undesired movement that the pilot seeks to control through the application of rudder.
  • Control of yaw is visually confirmed by the pilot by maintaining the ball positioned in the centre on the turn coordinator.

  • Movement about the normal (vertical) axis.
  • If not controlled properly, yaw leads to roll movement and an eventual nose-down attitude.

Cause of  yaw:

  • Torque effect
  • slipstream
  • P-factor
  • Gyroscopic precession

Propeller Torque Effect

  • “For every action , there is an equal and opposite reaction”
  • Torque is the result of the engine spinning the propeller. The prop spins clockwise as seen by the pilot. The force exerted by the engine causes the airplane to twist counter clockwise.
  • As the result of the torque, the plane will try to bank to the left.
  • A little right aileron will counter act the bank action.

This is something we have to do automatically. It must be become second nature to keep the wings level.

TORQUE

The torque effect (left-turning tendency) is greatest at low airspeed, high angles of attack, and high power, e.g., on takeoff.

Slipstream Effect

  • As the prop spins clockwise ( from the pilot’s view ), a swirl is created in the air behind the prop. The wind swirling around the plane comes in contact with the vertical stabilizer.
  • The slip stream striking the tail pushes the tail to the right. This yaws the plane to the left.
  • The right rudder is used to counteract the slipstream effect.

P-Factor

  • P-factor (asymmetric propeller loading) causes the airplane to yaw to the left when at high angles of attack because the downward moving blade of the propeller (as seen from the rear) has a higher angle of attack than the upward-moving blade and provides more thrust.
  • The right rudder is used to counteract the P-Factor effect (Yaw to the left).

Gyroscopic Precession

  • Precession is the resultant action, or deflection, of a spinning rotor when a deflecting force is applied to its rim., when a force is applied, the resulting force takes effect 90° ahead of and in the direction of rotation and in the direction of application.
  • The resultant force acting 90° ahead causes a yawing moment to the left around the vertical axis.

Adverse Yaw

  • 1) Tendency for an airplane to yaw opposite the direction of roll when initiating a turn
  • (2) when an airplane rolls into a turn, the wing is being raised creates more lift that the wing being lowered.
  • (3) the raised wing also creates more drag.
  • (4) because of the uneven drag components on either side of the longitudinal axis, the airplane wants to yaw towards the raising wing.
  • To counteract adverse yaw, correct rudder pressure must be applied when initiating a turn.
  • (5) Turns to the right display more adverse yaw than turns to the left because of the natural left turning tendencies our airplane exhibits, the adverse yaw is counteracted a bit more.
  • Moving the control wheel to the right causes the right aileron to deflect upward and the left aileron to deflect downward.
  • The upward deflection of the right aileron decreases the camber resulting in decreased lift on the right wing. The corresponding downward deflection of the left aileron increases the camber resulting in increased lift on the left wing.
  •  Thus, the increased lift on the left wing and the decreased lift on the right wing causes the airplane to roll to the right.
  • Since the downward deflected aileron produces more lift, it also produces more drag. This added drag attempts to yaw the airplane’s nose in the direction of the raised wing. This is called adverse yaw.

Look out !!!

Collision avoidance, both in the air and on the ground, is one of the most basic responsibilities of a pilot flying in visual conditions.

The Scan techniques

Divides the sky into blocks, each spanning 10 to 15 degrees of the horizon, and 10 degrees above and below it—for a total of 9 to 12 blocks, or scan areas.

Side-to side scanning method: Start at the left of your visual area and make a methodical sweep to the right, pausing in each block of viewing to focus your eyes. At the end of the scan, return to the panel.

Front-to-side scanning method: Start at the center block of your visual field (center of front windshield); move to the left, focusing in each block then swing quickly back to the center block after reaching the last block on the left and repeat the performance to the right.

The clock code

  • The method of reporting the position of other aircraft you can see is based on the clock code.
  • Simply, an aircraft directly in front of the aircraft is known to be at 12 o’clock and one directly behind is at 6 o’clock.
  • To this direction you can also add ‘High’ or ‘Low’ depending on where the aircraft is in relation to you.
  • As an example, you see an aircraft flying below your left wingtip about 1 mile away. You would identify this aircraft as aircraft at 9 o’clock, low, 1 mile.

  Review questions

  • If the nose of the airplane is above the horizon (reference datum) we say that the aircraft is?
  • If it’s below we say?
  • How the wings are if the aircraft is in cruise attitude?
  • When backward pressure is applied to the control column the nose……?
  • When forward pressure is to applied to the control column the nose….?
  • When the aileron control is moved to the right the aircraft roll to the….?
  • What are the causes or yaw ?
  • What is the main control to counteract the yaw ?
  • If an airplane arrive in front of me, based on the clock code, where is it ?