Lecture Notes: How Do Planes Fly and Einstein's Flawed Wing Design

Introduction

• By 1917, Albert Einstein had explained space-time but designed a flawed airplane wing.
• Flawed due to incomplete theory of flight; misconceptions about flight still exist.

Basics of Flight

• Air as Fluid: Air is a fluid medium, less dense than water.
  • Buoyant: Lighter-than-air objects.
  • Lift: Required upward force for heavier objects to stay aloft.
• Wings and Lift: Wings primarily generate lift for planes.

Misconceptions About Lift

• "Longer Path" or "Equal Transit Time" Explanation:
  • Incorrect theory that air traveling over the wing must travel faster to meet air traveling below.
  • Debunked: Air above the wing reaches the trailing edge faster than below.

Real Mechanism of Lift

• Air Movement Around the Wing:

  • As wing moves, air is diverted above and below.
  • Centripetal acceleration increases speed of air above the wing.
  • Lower pressure above creates more lift.

• Pressure Differences:

  • Higher pressure below the wing compared to above.
  • Greater speed increases pressure difference and lift.
  • Lift overcomes gravity, allowing takeoff.

Wing Design Considerations

• Curvature and Lift:

  • Wing curvature isn't sole cause of lift.
  • A flat wing tilted upwards can also generate lift.
  • Excessive curvature or steep angle can cause turbulent detachment.

• Einstein's Design:

  • "The cat’s back" wing design increased curvature.
  • Resulted in unstable flight (e.g., "pregnant duck" wobble).

Complexities in Lift

• Other Influences:

  • Air beyond wing’s surface contributes to lift.
  • Wing tip vortices also play a role.

• Experts' Views:

  • Consensus on pressure difference causing lift.
  • Different focuses: air behavior at wing vs. deflected air's upward force.

• Equation for Modeling Lift:

  • Navier-Stokes equations: used to model air flow and lift.

Conclusion

• Despite Einstein's failed attempt, the principle of lift is complex and nuanced.
• Physics of fluid in motion is key to understanding flight.

Sponsorship Note

• Video was supported by Marriott Hotels, promoting travel curiosity.