Straight and Level Flight

Straight-and-level flight

Straight-and-level flight is flight in which a constant heading and altitude are maintained.

Objectives of the lesson

  • To flight straight and level (constant heading, selected altitude and airspeed) at various speeds within the full operational speed range of the aircraft.
  • The combination of attitude and power to achieve performance.

In the previous lecons

  • Cruise attitude: The cruise attitude is attained with level flight attitude, a constant altitude, a constant airspeed and power, and level wings.
  • Control yaw with rudder.
  •  Increase power:   yaw to the left:   right rudder.
  •  Decrease power: yaw to the right: left rudder.
  •  Cause of yaw:   Bank attitude, slipstream effect , asymmetric thrust.

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Straight flight

  • Straight means: No turn.
  • Straight flight is maintained by keeping the wings level with ailerons and applying the necessary pressures on the rudder pedal to prevent yaw.
  • If you allow the aircraft to bank it will begin to turn in direction of the lower wing.

Straight flight control of Yaw.

  • An increase in power, which increase the rotational force of the propeller slipstream, will cause aircraft with clockwise rotating propeller to yaw to the left.
  • A decrease in power will cause the aircraft to yaw to the right.
  • Any tendency for the aircraft to yaw with power change should be anticipated and prevented by appropriate use of rudder.

Level Flight

  • Level flight means flying at a constant altitude, not going up and down.
  • As power is increased or decreased, keep the pitch attitude constant with appropriate elevator control pressure.
  • When the aircraft is at the desired airspeed, trim to relieve the control pressure required to maintain straight-and-level flight.
Attitude+power=performance

This formula simply states that for any given attitude (pitch and bank) and power setting, a certain performance will result.

When an aircraft is in straight-and-level flight  forward or backward pressure on the control column will affect both speed and height. Likewise , changes in power settings can affect both speed and height.

To increase the airspeed while in straight-and level flight.

  • Advance the throttle smoothly to the power setting estimated for the speed desired.
  • Anticipate the yaw to the left with the right rudder.
  • At the same time apply sufficient forward pressure to the control column to keep the altitude from increasing.
  • Keep the wing level.
  • When the desired airspeed is reached, readjust the power setting if necessary,  then trim the aircraft.

To decrease the airspeed while in straight-and-level flight.

  • Throttle back smoothly to the power setting estimated for the speed desired.
  • Anticipate the yaw to the right with the left rudder.
  • Back pressure to the control column to maintain the desired altitude.
  • Keep the wing level.
  • When the desired airspeed is reached readjust the power setting if necessary, then trim the aircraft.

Resume

To change airspeed at level flight without changing the altitude.

To increase airspeed :

  • Increase power.
  • Lower the nose.

To decrease airspeed :

  • Decrease power.
  • Raise the nose.

This plane has a pitch nose up but it could be in straight-and-level flight at reduced airspeed.

Straight and level flight instruments

The six pack: the six main flight instruments.

No change in theses instruments mean that we are in straight-and-level flight.

  • Use ailerons to keep wings level
  • Use elevator and power to maintain altitude and airspeed
  • Use rudder to control yaw

Trim technique

  • As you increase and decrease airspeed, you will feel pressure on the control as you try to maintain level flight.
  • Once the new speed and/or pitch attitude is established, eliminate the control pressure by trimming the aircraft.

Review questions

  • When reducing power in level flight, what control movement will be necessary to maintain straight and level flight ?
  • What Attitude + Power = Performance means?
  • When adding power to accelerate what else will you have to do?
  • What happened with visual reference if I increase the pitch attitude?
  • Why is trimming the aircraft important?