21st Century Pacific Students Construct A Great Launcher of Siege Assembled by: See Yang Hans Roelle Nicole Solari Rim Madani (Thursday 4-6) December 04, 2003

1
21st Century Pacific StudentsConstruct A Great
Launcher of SiegeAssembled by See YangHans
RoelleNicole SolariRim Madani(Thursday
4-6)December 04, 2003
2
Overview/Outline

1. Project Description
2. History
3. Modern Improvements
4. Design Tips and Guidelines
5. Safety Considerations
6. Design Construction
7. Analysis Proposed Design
8. Completion Performance
9. Suggestions
10. Acknowledgement

3
Project Description

• To design and construct a TREBUCHET that is able
  to launch a hacky sack as far and accurate as
  possible.
• Trebuchet an ancient siege engine used for
  throwing objects

TASKS 1. Research 2. Design development 3.
Build actual model. 4. Performance Test
5. Final/Competition 6. Presentation 7. Final
Report
4
History

• Used for destroying barricading walls
• 4th century BC - first invented in China
• 6th century AD - made its way to Europe
• (used to hurl stones, cows, rotting flesh, etc.)
• In England, it was referred to as Ingenium
• 16th century - became obsolete

5
Modern Improvements

• Usage of Newtons Second Law of Motion to modify
  designs (principles of physics)
• The addition of wheels to increase momentum
• Development of new materials for counter weight
  (massive solid vs. rocks)
• Different/stronger sling material
• Usage of light weight building materials

6
Design Tips and Guidelines

• Find ratio of counter weight vs. arm that best
  optimizes hurl distance
• Hinge the weight so it is free falling
• Have the weight fall as vertically as possible
  for maximum acceleration
• Have counter weight arm at a minimum weight
• Have stable based frame
• When drilling the hole for the dowel, make sure
  its as straight at possible
• Use as much simplicity as possible

7
Safety Considerations

• Always wear safety goggles at every step of the
  construction process and launching of the
  trebuchet
• Keep a safe distance from the trebuchet when
  launching, somewhere around six feet
• Keep all appendages away from the sling or
  release mechanism of the trebuchet to prevent
  injury to yourself or others
• Prevent yourself and others from putting harmful
  objects into the sling as they may be hurled and
  injure someone
• Do not use sharpened metals in construction as
  they may injure someone during operation

8
ALWAYS TAKE SAFETY PRECAUTIONS BEFORE OPERATING!!!
9
Design and Construction Requirements and Scoring
Criteria

• Limitations/Constraints
• Hurl a Hacky Sack of weight 28.8g or 1 oz
• Cannot exceed 4ft long x 3ft wide x 2.5 ft tall
• Must use a counter weight that does not exceed 12
  lbs
• Must release arm from a distance no less than 10
  ft
• Weight penalty incurred per pound

10
Analysis and Proposed Design
11
Analyses Overview

• I. Design criteria discussion
• II. Analytical discussion
• A. Theoretical energy analysis
• B. Dynamic Computer Simulation
• III. Proposed Design
• A. Proposed Materials to be used
• B. Estimated Cost

12
Design Criteria Discussion

• In this portion of our project, we discussed how
  the truss should be put together, the base
  strength, the height, the arm length, the
  distance at which the counter weight is hanging
  from the arm, the length of the sling, and what
  material to use for the pouch.

13
Analytical Methods

• Projectile range with no air resistance

Energy balance
Combining range and energy equation
R projectile range g gravity h height
mc mass of counter weight mm mass of
missile (hacky sack) V0 initial velocity
In order to maximize the range, the total
height needs to be maximized
14
Analytical Methods (cont.)

• Dynamic Computer Simulation Discussion
• In order to maximize the range, we experimented
  with all the variables in the figure to the left.
  
• First, we started with all the given information.
  From there on, we experimented with different
  lengths of L1, L2, L3, L4, and L5. After finding
  the most efficient values for the variables, we
  experimented with the most efficient angles to be
  used.

15
Analytical Methods (cont.)

• Computer Simulation Results

16
(No Transcript)
17
(No Transcript)
18
Proposed Design

• In our proposed design, we made the base wide so
  the trebuchet would be stable. We also set our
  dimensions and lengths in accordance with the
  computer simulation. It seemed that in the
  simulation, by changing one measurement, the rest
  of the trebuchet lengths were changed.

19
Proposed Design (cont.)

• Materials Used
• Pine (1x 2) (2x 2)
• Screws
• Wooden dowel (1)
• Nylon rope
• Shami
• Wood putty
• Eye bolts (appr. 4)
• PVC pipe (1- 3.5 dia.)

• Estimated Cost
• Due to the fact that Nicole already has supplies
  at her house, we are fortunate enough to have our
  supplies donated.
• If we do need supplies, we have estimated an
  amount of 25.

20
Construction and Performance
21
Construction methods

• To begin the project, we first sat down together
  and gathered all our thoughts. Before beginning
  to cut the pieces, we drew out a rough sketch of
  how we were going to put the trebuchet together.
• Step 1 measure all the pieces
• Step 2 we put the base together
• Step 3 measure and cut all angles for the legs
  that are to fit at an angle
• Step 4 screwing all the pieces together
• Step 5 getting the holes in for the dowel
• Step 6 cut the dimensions of the arm
• Step 7 fix the track
• Step 8 fix the sling, pouch, and release
  mechanism
• Step 9 fix the counterweight

22
Pictures
23
Pictures
24
Pictures
25
Pictures
26
Pictures
27
Pictures
28
Construction methods (cont.)
Problems Solutions
Angles of Bracings Add wedges and end caps
Angling of truss Modify design so trusses would stand vertical
Use of nails to attach pieces Use screws instead of nails
Drilling the hole on the arm for the dowel Added an extra piece to straighten the dowel
Release mechanism wouldnt lock into place Moving the release attachment
Size of swing arm Shorten the end of the swing arm where the counter weight is attached

• In our actual building of the trebuchet, we
  changed a lot of the dimensions and design. The
  reason we changed our design and dimensions was
  so make it easier on our part. We ARE humans and
  cannot be exact, and our changes did make a
  difference.

29
Completion of the Trebuchet
30
Optimizing hurl distance

• For our first trials, we kept the all the
  measurements as calculated by the simulation.
• Step 1 experimented with different sling
  length to find the optimum performance length
  (between 30-40 ft)
• Step 2 experimented with shortening and
  lengthening the distance between the
  counterweight and the ground (between 20-30 ft)
• Step 3 experimented with different release
  angles (distance varied between 0-40)
• Step 4 shorten the length of the arm connected
  to the counterweight (50 ft)
• Step 5 repeated steps 1, 2, and 3
• Other factors that affected the range were the
  weight of the arm, the overall weight of the
  trebuchet, and air resistance.

31
What would we do differently?

• Group
• Started earlier on the construction portion of
  the project
• Figured out the angles and lengths at reasonable
  measurements
• Trebuchet
• Maximizing height of trebuchet
• Use a lighter arm
• Add wheels
• Reduce the total weight
• Use different release pin
• Use different sling material
• Make the counterweight drop as straight at
  possible
• Drilling a straight hole through the arm

32
Conclusions and Recommendations

• Most helpful design processes
• Our design goals were met in terms of weight and
  size
• We learned a number of interesting aspects in
  math and physics to help aid us in the design
• The construction process helped us understand
  that the computer simulation was just a
  theoretical estimation of the results
• Collaboration of ideas
• Examples of trebuchets on the web
• Least helpful design processes
• There werent different measurements
• The drawings we made were not detailed enough
• The weight of the arm

33
Recommendations (cont.)

• Recommendations for future trebuchet builders
• Using better materials, connections, and
  construction tools
• Run as many test trials as you can
• Time management
• Try not to get off task
• Dont be afraid to argue with your teammates to
  get your point across
• Leave criticism with the project (dont take it
  personally)
• Have spare parts available
• Be flexible
• Have fun!!!

34
Acknowledgement

• Bullock, Tom. 11 January 2000. Trebuchet. 8
  October 2003
• lthttp//www.tbullock.com/trebuchet.htmlgt 
• Carliste, Paul. 1 February 1998. The Trebuchet.
  8 October 2003
• lthttp//www.ameritech.net/users/paulcarliste/treb
  uchet.htmlgt 
• Geiselman, Kevin A. 27 May 2002. Ingenium. 8
  October 2003
• lthttp//tasigh.org/ingenium/medium.htmlgt 
• Gray Company Trebuchet Page. February 2000. 8
  October 2003.\
• lthttp//members.iinet.au/rmine/gctrebs.htmlgt 
• Grimminck, Micheal. 16 April 2001. Basic
  Physics Formulae. 8 October 2003
• lthttp//xs4all.nl/mdgsoft/catapult/ballistics.ht
  mlgt 
• Ludlam, Eric M. 1 June 2003. Siege-Engine.com.
  8 October 2003
• lthttp//www.siege-engine.com/gt
•  Radlinski, Filip. Welcome to the Physics of the
  Trebuchet. 8 October 2003
• lthttp//www.geocities.com/Silicon
  Valley/Park/6461/trebuch.htmlgt
•  

35
Acknowledgement (cont.)

• Ripcords Trebuchet Stuff. 23 August 2003. 8
  October 2003.
• lthttp//www.ripcord.ws/gt
•  Trebuchet. 10 February 2003. 8 October 2003.
• lthttp//www.io.com/beckerdo/other/trebuchet.html
  gt
•  Trebuchet. 8 September 2003. Wikipedia. 8
  October 2003.
• lthttp//www.wikipedia.org/w/wiki.phtml?titletreb
  uchetprintableyesgt
•  Trebuchet.com. 8 October 2003.
• lthttp//www.trebuchet.comgt
•  Trebuchet at NF/Observatory. 8 October 2003.
• lthttp//www.nfo.edu/trebuche.htmgt
•  Vaarma, Jari. 20 July 2001. Siege Engine Page.
  8 October 2003
• lthttp//www.students.tut.fi/vaarma/siege/siege.h
  tmgt

36
Acknowledgement (cont.)

• Thank you Linda, Charlene, Hanh, and James for
  letting us borrow your power drill and donating
  screws.
• Thank you to Professor Litton and Professor
  Golinbari for all your help.