Ancient Machines “The Siege Engine Edition”
Big Idea: More than Manpower <ul><li>Humans like the easy way out: developed technology to help construct pyramids, waterw...
Mechanical Advantage
What Goes Up… <ul><li>Most ancient machines were used to create, rather than destroy. </li></ul>
…Gets Knocked Down <ul><li>Forts, Castles, Walls of all shapes and sizes = Tempting Targets! </li></ul>
Catapults <ul><li>Storing Tension – lots of tension! </li></ul><ul><li>Ratchet Gears work as a winch: a piece of metal cal...
Activity: Coat Hanger Catapults Bend a coat-hanger into a catapult base, wind up a rubber band and test your flinging mach...
Trebuchets <ul><li>A trebuchet works with a lever and counterweight, using gravity (potential energy transformed to kineti...
Success or Splat? <ul><li>Be a siege engineer! </li></ul><ul><li>NOVA: Destroy the Castle  http://www.pbs.org/wgbh/nova/lo...
Activity: Testing Trebuchet Range <ul><li>Try out our working tabletop trebuchet!  Try for distance or for one of the targ...
Projectile People—Possible? <ul><li>Also known as: my favorite movie stunt </li></ul>
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Ancient Machines: Siege Engines

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Introduction to a hands-on program in building and experimenting with models of siege engines (catapults and trebuchets).

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Ancient Machines: Siege Engines

  1. 1. Ancient Machines “The Siege Engine Edition”
  2. 2. Big Idea: More than Manpower <ul><li>Humans like the easy way out: developed technology to help construct pyramids, waterwheels, castles </li></ul><ul><li>Wedges, levers, wheels, etc all use alternate sources of power to ease the work involved. </li></ul><ul><li>Gravity and tension are today’s 2 power sources. </li></ul>
  3. 3. Mechanical Advantage
  4. 4. What Goes Up… <ul><li>Most ancient machines were used to create, rather than destroy. </li></ul>
  5. 5. …Gets Knocked Down <ul><li>Forts, Castles, Walls of all shapes and sizes = Tempting Targets! </li></ul>
  6. 6. Catapults <ul><li>Storing Tension – lots of tension! </li></ul><ul><li>Ratchet Gears work as a winch: a piece of metal called a ‘pawl’ keeps the gears only rotating in one direction. </li></ul><ul><li>Releasing the tension on the spring arm makes it fly up until it hits the stop-bar. </li></ul><ul><li>Notice the extra construction to keep the stop-bar from snapping under the pressure. </li></ul>The ancient Romans were excellent engineers. Many of the things they built are still standing today.
  7. 7. Activity: Coat Hanger Catapults Bend a coat-hanger into a catapult base, wind up a rubber band and test your flinging machine! For obvious safety reasons, we will not be throwing rocks, marbles, or anything hard.  Feel free to experiment and modify your design at home! … In which we learn that experiments with rubber bands and sponges will hurt less than the alternative.
  8. 8. Trebuchets <ul><li>A trebuchet works with a lever and counterweight, using gravity (potential energy transformed to kinetic) to fling the projectile. </li></ul><ul><li>Range and accuracy can be altered by changing the length of the swinging arm, the mass of the ball, the mass of the counterweight, and several other factors. </li></ul>
  9. 9. Success or Splat? <ul><li>Be a siege engineer! </li></ul><ul><li>NOVA: Destroy the Castle http://www.pbs.org/wgbh/nova/lostempires/trebuchet/destroywave.html </li></ul><ul><li>GlobalSpec: Treb Challenge http:// www.globalspec.com /Trebuchet/ </li></ul>
  10. 10. Activity: Testing Trebuchet Range <ul><li>Try out our working tabletop trebuchet! Try for distance or for one of the targets. </li></ul><ul><li>Remember not to fire AT anyone, and stay out of the firing line while waiting your turn. </li></ul><ul><li>Please remember to recover your “ammunition” after each firing! </li></ul>The “Little Dragon” Trebuchet was the model for our version.
  11. 11. Projectile People—Possible? <ul><li>Also known as: my favorite movie stunt </li></ul>

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