Notes on How Airplanes Fly and Are Controlled

Introduction

• Engineering Marvels: Modern airplanes can navigate turbulent air and perform complex maneuvers.
• Objective: To explore how airplanes fly and how pilots control them using logical methods.
• Special Thanks: SimScale for CFD support.

Airplane Anatomy

• Wings and Tails: Composed of movable parts, not a solid piece.
• Airfoil Shape: Critical in fluid mechanics for generating lift.

Understanding Airfoils

• Lift Production:

  • An airfoil produces lift by creating a downwash, resulting in pressure differences between the top and bottom surfaces.
  • Higher angle of attack increases downwash and lift.
  • Increased airspeed also leads to greater lift.

• Historical Context: The Wright Flyer utilized basic airfoil principles, demonstrating sufficient downwash with simple curved shapes.

• Techniques to Increase Lift:

  1. Increase angle of attack
  2. Alter airfoil shape
  3. Increase wing area

Aircraft Control Mechanisms

• Flaps and Slats: Activated to increase downwash and lift during takeoff.
• Ailerons: Control lift by moving up or down, affecting the aircraft's roll.
• Tail Controls:
  • Rudder: Controls horizontal movement.
  • Elevators: Affect vertical force on the tail.

Takeoff Procedure

• Lift Force: Must exceed gravitational pull.
• Steps for Takeoff:
  1. Increase engine thrust for speed.
  2. Activate flaps and slats to boost lift.
  3. Pull elevators up to tilt the airplane and increase angle of attack (usually 15 degrees).

Engine Thrust Generation

• Turbofan Engines: Provide thrust through fan reaction and exhaust force.
• Fuel Storage: Located in the wings.

Climb Phase

• Thrust vs Drag: As long as thrust exceeds drag, speed and lift will increase, allowing ascent.
• Level Flight: Thrust equals drag, and lift equals weight.

Changing Direction

• Rudder's Role: Produces horizontal force, but not ideal for direct turns due to passenger discomfort.

• Centrifugal Force: Achieved by adjusting ailerons.

  • One aileron up and the other down creates roll, shifting lift's direction.

• Adverse Yaw: Imbalance in drag forces during aileron operation can cause yaw, requiring rudder adjustment.

Use of Technology

• Fly-by-Wire System: Control computers manage wing attachments for precise handling.

Descent and Landing

• Descent Procedure:
  • Reduce thrust and lower the nose.
• Landing Techniques:
  • Activate flaps and slats to increase drag.
  • Use spoilers for additional drag.
  • Reverse Thrust: Redirects exhaust forward to aid in stopping.

Conclusion

• Simulation Insights: CFD simulations provided by SimScale are beneficial for understanding complex aerodynamics.
• Call to Action: Create an account at SimScale.com for further exploration of CFD analyses.