Science of Submarines

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Science of Submarines

• The Turtle

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The Turtle Submarine
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Module Objectives

• Learn about the Turtle submarine, its design
  issues and some of its exploits during the
  Revolutionary War.
• Learn about buoyancy, what makes some objects
  float and others sink Archimedes Principle and
  Pascals Principle.
• Learn about stability, what keeps objects upright
  on and below the ocean surface.

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The Turtle

• Propelled by pedals and cranks, hand-and-foot
  operated
• Descended using valve to admit water to ballast
  tank, ascended using pumps to eject water
• Equipped with a depth gauge, a compass, and a
  ventilator to supply fresh air when the vessel
  was on the surface.

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The Turtle

• Inflicted no damage to any British vessel, but
  changed course of British strategy through her
  use as a potential weapon
• Alleged to have been sunk by British while being
  transported to a battle site
• From a warrior's mentality, the submarine was
  a great addition to the world's war arsenal

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Turtle Engineering/Design Issues

• Engineering/design problems that had to be solved
  with the technology of the time
• watertight, pressure-proof hull
• vertical and horizontal propulsion
• vertical stability
• variable ballast
• steering controls
• weapons-delivery system.

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Turtle Engineering/Design Issues

• Engineering/design problems that had to be solved
  with the technology of the time
• watertight, pressure-proof hull
• vertical and horizontal propulsion
• vertical stability
• variable ballast
• steering controls
• weapons-delivery system.

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Turtle Engineering/Design Issues

• Engineering/design problems that had to be solved
  with the technology of the time
• watertight, pressure-proof hull
• vertical and horizontal propulsion
• vertical stability
• variable ballast
• steering controls
• weapons-delivery system.

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Turtle Engineering/Design Issues

• Engineering/design problems that had to be solved
  with the technology of the time
• watertight, pressure-proof hull
• vertical and horizontal propulsion
• vertical stability
• variable ballast
• steering controls
• weapons-delivery system.

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Turtle Engineering/Design Issues

• Engineering/design problems that had to be solved
  with the technology of the time
• watertight, pressure-proof hull
• vertical and horizontal propulsion
• vertical stability
• variable ballast
• steering controls
• weapons-delivery system.

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Buoyancy To Float or Not to Float

• Archimedes PrincipleAny object comp-letely or
  partially immersed in a fluid (liquid or gas) is
  buoyed up by a force equal to the weight of the
  displaced fluid.
• Pascals Principle Any change in pressure in
  a fluid is transmitted undiminished through the
  fluid

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Some Terminology Metric Units

• Mass is the amount of matter in an object units
  kilograms
• Weight is the measure of the force of attraction
  between objects due to gravity. units newtons
• Volume is the amount of space an object takes up
  units liters, meters3
• Density is mass per unit volume units
  grams/cubic centimeter (g/cc)

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Virtual Density Lab

• Use the tools in the Virtual Lab to find the mass
  and volume of the various objects.
• Drop the objects in the pail of water to see if
  they sink or float.
• Find a relationship between the mass and volume
  of the objects predict whether the objects float
  or sink.
• Density Lab

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Some Density Results
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Stability

• Consider a submarine with mass m, and displaced
  volume V below the waterline.
• The center of buoyancy (CB) is the mathematical
  average of all points below the waterline less
  dense than water.
• The center of mass (CM) is the mathematical
  average of all masses mechanically linked to the
  submarine.
• If CM is lower than the CB, the ship is said to
  be stable. If CM is above CB, the ship is
  unstable.
• Stability graphic

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References
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Computational Project Ideas

• The density of sea water is a function of
  pressure, temperature, and salinity. The flux of
  heat in and out of the ocean is constrained
  largely to the layer near the surface. At depth
  the ocean is approxi-mately adiabatic (no sources
  or sinks of heat). Find a formula which
  approximates density in sea water and calculate
  sea water densities for various oceans around the
  world. Compare your results with published data.

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Computational Project Ideas

• In the early 1940s, the US submarine Squalus
  was raised from the ocean floor by attaching
  air-filled pontoons to it. Consider the problem
  of raising an object of constant density from the
  ocean floor by attaching pontoons to it to
  increase its buoyancy. Bring the object to the
  ocean surface in an upright position.