Steep Turns


 

  1. In order to turn effectively, an airplane must be banked.

             [Draw picture of split forces in a turn] (AFH 3-8)
             i.      Vertical component of lift counters weight                                               

             ii.      Horizontal component turns the airplane (PHAK 4-19)

  1. Airplanes are banked using ailerons
    1. Ailerons increase or decrease lift of a wing
  2. A byproduct of lift is drag.  The lowered aileron (upper wing) creates greater drag, which produces adverse yaw
    1. Adverse yaw is yaw in the opposite direction of a turn
  3. To counteract adverse yaw, rudder is used simultaneously to make coordinated turns (AFH 3-8)
    1. Too little rudder creates a slipping turn
    2. Too much rudder creates a skidding turn
  4. Vertical component of lift must be equal to the weight to maintain altitude.
    1. AoA is increased by the elevator pressure (yoke back)
  5. Induced drag increases as lift increases
  6. To maintain airspeed, additional power/thrust is required to compensate for increased induced drag of the wing  (PHAK 4-20)
  7. There are three main types of bank
    1. Shallow banks require aileron input to prevent bank from returning to level flight (less than approximately 20°)
    2. Medium banks require no aileron input to maintain a constant bank (approximately 20° to 45°)
    3. Steep banks require opposite aileron input to prevent overbanking tendencies (approximately 45° or more)
  8. Overbanking tendency is created during a steep banked turn because the outside wing is producing more lift from increased airflow (think of a funnel) (AFH 3-9)

(Because the outboard wing is developing more lift, it also has more induced drag.  This causes a slight slip during steep turns that must be corrected by sue of the rudder.) (AFH 3-9)

Flying tip:  to recover from an excessively low nose the pilot should first reduce the angle of bank with coordinated use of the rudder an aileron, then raise the nose of the airplane to level flight with the elevator.  If elevator alone is used, it will cause a steepening of the bank and could result in overstressing the airplane. (AFH 3-9)

  1. Increased bank produces increased load factor
    1. Load factor is the stress put on an airplane, or how heavy the airplane feels

Load Factor:  the ratio of the maximum load an aircraft can sustain to the gross weight of the aircraft (measured in G’s).  Any force applied to an aircraft to deflect its flight from a straight line produces a stress on its structure, and the amount of this force is the load factor.  For example, a load factor of 3 means the total load on an aircraft’s structure is three times its gross weight.  Load factors are important for two main reasons:

  1. It is possible for a pilot to impose a dangerous overload on the aircraft structures.  (see table on PHAK 4-33)
  2. An increased load factor increases the stalling speed and makes stalls possible at seemingly safe flight speeds.

The load factor for any aircraft in a 60° bank is 2 Gs.  The load factor in an 80° bank is 5.76Gs.  The wing must produce lift equal to these load factors if altitude is to be maintained.

Increased load factors also increase stall speeds: in proportion to the square root of the load factor.  An aircraft that normally stalls at 50 knots can be stalled at 100 knots at 4 Gs. (PHAK 4-30)  At 60° of bank, the stall speed of the twinstar (normally 62 knots) will be closer to 88 knots.  At 70° bank (nearly 3 G’s) the stalling speed rises to about 107 knots.

 

Preflight Briefing:

Complete clearing turns before every performance maneuver—usually at least 180° change in direction, looking for traffic (Jeppesen Private Pilot pg. 4-6)

 

Power 50%

Below VA 120kts

(Altitude +/-100 ft +/-5°)

Roll through 30° Power 60%

50° Bank (+/-5°)

2-3° nose up to maintain altitude

Lead turn out by 15°

 

Flight:

 

Technical Subject Areas:

Visual scanning/collision avoidance

Preflight Preparation

Preflight Procedures

Takeoffs/Landings


       STEEP TURNS

  • Clearing Turns
  • Establish a heading and altitude to retain
  • Slow to approximately 110KIAS
  • Power 50%
  • Bank to 50° and apply 60% power (the extra power is needed to overcome the increased induced drag produced by the increased AOA–needed to supplement the vertical component of lift–lost to the horizontal component) (see AFH 9-2)
  • Coordinate rudder with aileron in the direction of the turn.
  • As you roll through 30° bank, apply back pressure to maintain altitude (this provides the higher AOA so the wing can produce enough lift to compensate for the [increasing load factor, or] vertical component of lift that was diverted to the horizontal component of lift)
  • Bank to 50° bank; use aileron to adjust bank and to correct the overbanking tendency
  • Trim the aircraft (elevator trim)
  • As you turn out on your original heading, “nose over” the aircraft by applying forward elevator(or ease back pressure if not using trim) in order to prevent ballooning
  • [optionally instead of using the elevator to compensate for the “extra lift” during the change in turn direction, you can reduce power back to original power, then increase for the next turn]
  • Smoothly and without pausing, turn the opposite direction; same procedure
  • Turn out on your heading as you decrease your power, an readjust trim

Common Errors

  • Failure to adequately clear the area
  • Excessive pitch change during entry or recovery
  • Attempts to start recovery prematurely
  • Failure to stop the turn on a precise heading
  • Excessive rudder during recovery, resulting in skidding
  • Inadequate power management
  • Inadequate airspeed control
  • Poor coordination
  • Gaining altitude in right turns, and/or losing altitude in left turns (Sinking to the left, floating  to the right)
  • Failure to maintain constant bank angle
  • Disorientation
  • Attempting to perform the maneuver by instrument reference rather than visual reference
  • Failure to scan for other traffic during the maneuver
  • Not being stabilized before you begin the maneuver
  • Not trimming immediately after established in the turn makes it much more difficult

Posture:  Do not lean to either side [usually to try and stay parallel with the ground] because it affects the interpretation of outside visual references.  (AFH 3-11)

 

Parallax error:  Side-by-side airplane configurations (either side of the longitudinal axis of the airplane) can create the illusion (from the left seat) that the nose appears to rise when making a left turn, and to descend when making right turns (thus the common error of gaining altitude in right turns and/or losing altitude in left turns).

 

Special Emphasis Areas:

Positive aircraft control in a high performance maneuver

Positive exchange of flight controls

Visual scanning/collision avoidance

 

Post-Flight Debriefing:

Identify tasks that were completed to standards or above.

Identify and discuss tasks that were not completed to standards.

Record and grade completed tasks in the training record.

Record training in the student’s logbook (reference Areas of Operation above)

Give an assignment for the next flight session.

 

Next Assignment: Prepare for completing this lesson by reviewing tasks that were not performed to standards. If all tasks were performed to standards, assign the next lesson’s required material.