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Stalls

Stalls
Power On and Power Off Stalls

Objective: The student will be able to understand what a stall is and where it will most likely to occur. The student will be introduced to stall aerodynamics and the characteristics of a stall. The student will also be introduced to the steps for an entry into a stall as well as the recovery from a stall.

Completion Standards: the student will be able to explain what a stall is and where we might encounter them. The student will also be able to explain  the procedures for power on and power off stalls including the entry the stall itself and recovery.

References: AFM ch 5

Equipment: White Board and markers, iPad/ computer 

IP’s Actions:

  • Assess student

  • State the objective and completion standards

  • Writes down references

  • Provide attention getter

  • Present content

  • Assessment

  • Assign Homework

SP’s Actions:

  • Take notes

  • Ask Questions

Introduction: 

(Attention Getter) : Paper airplanes and stalls

Motivation: have you flown a paper airplane so hard that it goes vertical but then slows and goes straight down. This is an example of a stall. 

Overview:

  1. What is a stall

  2. What Leads to a Stall?

  3. Stall Recognition

  4. Stall Characteristics

  5. Sample recovery from a stall

  6. Where can Stalls Occur

  7. Flight Maneuver’s

  8. Common Errors


Content:

What is a stall:

  • A stall is an aerodynamic condition which occurs when smooth airflow over the airplane’s wings is disrupted, resulting in loss of lift

  • When the AOA—the angle between the chord line of the wing and the relative wind—exceeds the wing’s critical AOA



What Leads to a Stall:

The Longer it takes to recognize an impending stall the more likely a full stall will occur!

  • Impending Stall

    • Occurs when the AOA causes a stall warning

    • Not yet reached the critical AOA.

      •  Indications of an impending stall can include buffeting, stick shaker, or aural warning. 

  • Full Stall

    • Occurs when the critical AOA is exceeded.

    • Indications of a full stall 

      • Are typically that an uncommanded nose down pitch cannot be readily arrested,

      • an uncommanded rolling motion. 

Stall Recognition:

  • Stall warning

    • For airplanes equipped with stall warning devices. 

      • Includes an aural alert, lights, or a stick shaker all which alert the pilot when approaching the critical AOA.

  • Sensory Cues

    • Feel

      • The pilot will feel control pressures change as speed is reduced.

      • less resistance on the control surfaces

      • Controls Feel Sluggish 

    • Vision

      • Can be stalled in any attitude

      • Maintaining pitch awareness is important


  • Hearing

    • As speed decreases, 

    • A change in sound made by the air flowing along the airplane structure.

  • Kinesthesia

    • The physical sensation

    • Seat of the pants

      • Changes in Direction and Speed


Stall Characteristics:

  • Factors that can affect the stall characteristics of an airplane

    •  include its geometry, CG, wing design, and high-lift devices.

    • Explain how CG can affect stall characteristics

  • Design of wings 

    • so that the wings stall progressively outward from the wing roots (where the wing attaches to the fuselage) to the wingtips

  • Twist, known as washout, resulting in the outboard portion of the wings having a slightly lower AOA than the wing roots

    • causes the wingtips to have a smaller AOA during flight than the wing roots. Thus, the wing roots of an airplane exceed the critical AOA before the wingtips, meaning the wing roots stall first.

    • the ailerons should still have a degree of control effectiveness until/unless stalled airflow migrates outward along the wings

Sample recovery from a stall:

  1. Disconnect the wing leveler or autopilot (if equipped).

    1. Manual control is essential to recovery in all situations.

  2. Pitch nose-down control.

    1. Reducing the AOA is crucial for all stall recoveries.

  3. Roll wings level.

    1. This orients the lift vector properly for an effective recovery. 

  4. Add thrust/power.

    1. Power should be added as needed, as stalls can occur at high power or low power settings or at high airspeeds or low airspeeds.

    2. Advance the throttle promptly, but smoothly, as needed 

    3. while using rudder and elevator controls to stop any yawing motion.

  5. Return to the desired flightpath.

Where can Stalls Occur:

  • During takeoff

    • Known as Power On Stall

  • During approach/ landing

    • Known as Power off stall

Flight Maneuver’s:

Power On Stall

Entry

  1. Clear the Area

  2. Choose altitude no lower than 1500’

    1. Preferably 2000’ or above

  3. Bug heading/ reference point above the horizon

Stall No flaps

  1. On selected heading/ reference point

  2. Bring power to 1500 RPM

    1. Slowing to rotation speed/ 55 kn

  3. Upon reaching 55 kn pitch nose up to 18°-20°

    1. While adding power to full

    2. Stay coordinated by adding right rudder

  4. Listen for stall warning/ buffet

    1. Nose of plane will fall when a stall has occurred

Recovery/ Exit

  1. Upon hearing stall warning/ fully developed stall

    1. Reduce AOA

  2. Make sure throttle is full

  3. Once recovered

    1. Climb Vy to safe altitude/cruise

Power Off Stall

Entry

  1. Clear the Area

  2. Choose altitude no lower than 1500’

    1. Preferably 2000’ or above

  3. Bug heading/ reference point above the horizon

Stall With flaps

  1. On selected heading/ reference point

  2. Bring power to 1500 RPM

  3. At 110 Kn apply flaps 10

  4. At 85 Kn apply flaps full

  5. Once flaps are applied pitch for 65 kn

    1. Once established for 65 kn reduce power to idle

    2. While pitching up to about 10°

  6. Listen for stall warning/ buffet

    1. Nose of plane will fall when a stall had occurred

Recovery/ Exit

  1. Upon hearing stall warning/ fully developed stall

    1. Reduce AOA

  2. Add throttle to full

    1. Add right rudder and staying coordinated 

    2. Start a climb

  3. Flap recovery speeds

    1. Once in a climb/ positive rate

      1. Flaps to 20

    2. Once airspeed is above 60 

      1. Flaps 10

    3. Once airspeed is above 65

      1. Flaps up

  4. Once recovered

    1. Climb Vy to safe altitude/cruise

Common Errors:

  1. Failure to establish the specified configuration prior to entry. 

  2. Improper pitch, heading, yaw, and bank control during straight-ahead stalls. 

  3. Improper pitch, yaw, and bank control during turning stalls. d. Rough and/or uncoordinated use of flight controls. 

  4. Failure to recognize the first indications of a stall. 

  5. Failure to achieve a stall. 

  6. Improper torque correction. 

  7. Poor stall recognition and delayed recovery. 

  8. Excessive altitude loss or excessive airspeed during recovery. 

  9. Secondary stall during recovery


Conclusion:

Went over what a stall is

Went over what leading to a stall

Went over stall recognition

Went over stall characteristics

Went over a sample stall recovery

Went over power on and power off stalls


(Questions to assess student)

What is a stall?

How does AOA affect a stall?

Where would a stall occur?

What is our first step when we end up in a stall?


HW: 

Look over Power on  and power off procedures


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