morgan's+trebuchet

A little bit of physics.
  Trebuchet physics basically involves the principles of the lever and sling. The lever involves having the force at one end and the load at the other with a fulcrum. **

The frame is the body (base) of the trebuchet which is used to support the beam (arm) and the counter weight. ** **The counter weight is a large mass that hangs on the short arm of the beam. The sling is a sack used to hold the projectile until there is enough energy to launch it. A trebuchet is powered by either gravity (like a heavy load) or by a force that is strong enough to be able to throw the projectile (like a person pullin****g it back). When the sling accelerates, it creates an arc shape (actually a parabolic arc) until one end slips off of a pin. The angle at which this happens is called the release angle. Using its own momentum, the projectile continues to fly in an arc shape (a parabola) until falling to the ground.**

**My Trebuchet.**
- 2m fishing line - duct tape - counter weight is a 14gauge steel cube filled with pennies and a hook welded on. total mass of counter weight 1.5kg. - 2 washers - 14 1 1/4" drywall screws - hook bolt and nut - 2 pieces of copper pipe (cut 5.5cm long) - 3 sheet metal screws - 1/2" dowel 19cm long - 2 pieces of pine cut 6.5cm/96cm/2cm - 2 copper pipe clamps - 1 bent wall hook - 2 pieces of pine cut 3cm/15.5cm/2cm - 2 pieces of pine cut 3cm/50cm/3cm - 1 piece of pine cut at 3cm/85cm/2cm - 4 pieces of pine cut 3cm/66cm/2cm one end cut at 44.7°, and the other at 40.3°
 * Materials used:**

=building and testing:= What I first did was research the internet for different types of trebuchets. I came to the conclusion that although the floating arm trebuchet is more effective, it is often heavier than the conventional trebuchet (my design). Which is why i decided on my design because of the equation we used to calculate our scores (P=d/M x La). When doing my research I came across a trebuchet simulator called __Trebstar__. This is what i used to do my testing and to find the ideal size for my trebuchet. The simulator calculated the theoretical P it would get was about 13. This simulator was very handy, but it was also the downfall of my project because it didn't take into account the air resistance on the ball in the air. The actual P my trebuchet achieved with the christmas ball was 1.55 which is significantly lower than what the simulator projected and since i relied solely on the simulator for my testing my trebuchet was inefficient when throwing the christmas ball. (a picture of the simulator is below)



sources:
http://www.medieval-castle-siege-weapons.com/trebuchet-physics.html http://library.thinkquest.org/05aug/00627/phy.html