Lecture Notes: Mass and Balance in Aviation

Introduction

• Focus on cargo loading and its importance in aviation.
• Discuss the calculation of forces and moments on board.
• Understanding the placement of cargo and passengers.

Cargo Loading Limitations

1. Maximum Load Limitations

   • The total weight or mass that can be carried in the cargo hold.

2. Maximum Linear Load Limitations

   • Restriction based on load per unit length of the cargo floor.
   • Example: Plank of wood between two chairs bending under weight.
   • Expressed as mass per distance (e.g., kg/m or lb/ft).

3. Maximum Area Load Limitations

   • Restriction on load per unit area of the floor in the hold.
   • Similar to linear load limit but two-dimensional.
   • Expressed as weight/mass per area (e.g., kg/m² or lb/ft²).

Example Calculation

• Scenario: Determine if a 50 kg box can be carried based on area load.
• Steps:
  • Check maximum load (250 kg) vs. box weight (50 kg).
  • Calculate the area in meters squared for different orientations.
  • Check each area against the limitation.
  • Result: Only one orientation meets area load limitations.

Center of Gravity (CFG)

• CFG is crucial for aircraft control.
• Acts as the focal point where axes of rotation meet.
• Comparison to a seesaw: Balance is necessary for control.
• National Airlines 102 Example:
  • Cargo shifted during flight, moving CFG outside safe range.
  • Resulted in an unrecoverable pitch moment, leading to a crash.

Moments and Balance

• Moment: Rotation caused by a force times distance from the fulcrum (CFG in aviation).
• Example with Seesaw:
  • Balance calculated by equating moments.
  • Position of weight affects balance.

Forces on Aircraft

• Thrust: Forward force from engines.
• Weight: Downward force through CFG.
• Lift and Drag: Act through the center of pressure.

Moment Calculations in Aircraft

• Positive moments are clockwise, negative are anti-clockwise.
• Need to balance moments for stable flight.
• Example Calculation:
  • Calculate moments to determine aircraft stability and required counter-moments.
  • Tail of aircraft provides necessary counter-moment.

Importance of CFG Range and Balance

• Implications of CFG Movement:
  • Too far forward/back affects stability and control.
  • Forward CFG can increase stability but require more tail force.
  • Backward CFG can lead to insufficient control and potential disaster.

Summary

• Cargo loading and CFG’s importance in flight safety.
• Limitation types and examples in aircraft loading.
• Importance of drawing diagrams for clarity in calculations.
• Balancing moments to maintain aircraft stability and control.