Bronze Theory

1
The Principals of Flight

• Bronze Theory

2
Airflow
3
Bernoullis Theorem

• Daniel Bernoullli (1700-1782) was a Swiss
  mathematician.
• V x P Constant
• An increase in the speed of a fluid results in a
  simultaneous reduction in pressure.

4
Bernoullis Theorem
5
Sir Isaac Newton

• Isaac Newton (1643-1727) was an English
  physicist, mathematician astronomer.
• Newtons laws of motion.
• For every action there is an equal and opposite
  reaction.

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Airflow
7

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The Chord Line
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Centre of Pressure Movement
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Instability of the Wing
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The Tailplane - Balance
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Lift increases with Angle of Attack until the
critical angle is reached at which point the
airflow can no longer flow smoothly over the
wings upper surface. The wing has now stalled.
When the wing stalls the centre of pressure
moves rapidly towards the trailing edge, this
creates a nose down pitching movement.The
stalled wing also creates a lot of drag.
15
Angle of Attack.
16
Washout.
17
Ailerons at the Stall.
18
Stalling / Spinning

• We have seen from an earlier slide that when the
  wing gets to a certain A of A the lift it
  generates is reduced and that it will stall.
• Of course it is entirely possible that one wing
  will stall before the other, when this occurs if
  no corrective action is taken a spin is likely to
  develop.
• This process is known as Autorotation, and
  results from the combination of loss of lift and
  increased drag on the stalled wing.
• The next slide will help to clarify this.

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Auto Rotation.
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Lift Distribution
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Wing Tip Vortices
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The Boundary layer

• Modern sailplanes use laminar flow airfoils, for
  these to work the wing surface must be smooth and
  retain the cross section that the designer
  intended.
• Laminar flow sections have a thin boundary layer
  of air directly in contact with the wings surface
  which moves in a smooth orderly (i.e. laminar)
  fashion from the leading edge towards the
  trailing edge.

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The Boundary Layer
25
The Boundary layer

• At some point during this chordwise movement of
  the air, the flow will become turbulent, the
  point at which this occurs is called the
  transition point.
• The turbulent air is a major source of drag.

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The Boundary layer

• It has been found that it is more efficient to
  trip the boundary layer to turbulent flow before
  it occurs naturally.
• This process of tripping the boundary layer is
  usually achieved by applying a span wise strip of
  zig - zag plastic tape.

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Vector Diagrams
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Vector Diagrams
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Vector Diagrams
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Accelerated Flight
37
Forces in a Turn
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Forces in a Turn
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ASI Colour Bands
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Water Ballast
41
Compass Errors
42
Compass Errors

• In the Northern hemisphere the following will
  happen.
• When flying East or West if you accelerate the
  compass will swing to the North, if you
  decelerate it will swing to the South.
• To help you remember this
• ANDS Accelerate North, Decelerate South.

43
Compass Errors

• In the UK the compass will lead by 25 30
  degrees when turning onto a Northerly heading, it
  will lag by a similar amount when turning onto a
  Southerly heading.
• To help you remember this
• SLAG South Lag.