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Project 3:

By Group 3: Thao Tran, Sean Gillespie, Von Kaukeano

TREBUCHET DESIGN

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Task Outline*

1. History

2. Problem Statement

3. Project Management

1. Roles

2. PERT & Gantt chart

4. Define the working goals

5. PDS- Product Design Specifications

6. Document Concepts

1. Brainstorm and Research

2. Alternate concepts

3. Refine problem statement and PDS

4. Pugh tables

5. Modeling/testing/

7. Detailed budget and list of materials                                                      

8. Construction

9. Construction report

10. Performance results                                  

11. Improvement

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History

The traction trebuchet is believed to be an ancient war engine which was invented in

China in 300BC. It is thought that the trebuchet may have developed from the stave sling. In the

traction trebuchet a large troop of men pulled down on ropes to propel the missile. The trebuchet

reached Europe during the Medieval era in 500 AD and was used extensively by the French and

the troop of men were replaced with a large fixed, or pivoting, counterbalance weight. The

Trebuchet (Trebuchet) was introduced in England in 1216 during the Siege of Dover - as were

many other types of siege engine. Louis the Dauphin of France crossed the Channel with a large

force and laid siege to Dover Castle making a violent and incessant attack on the walls. He used

the trebuchet against the walls of Dover Castle. The constable of Dover castle was Hugh de

Burgh - he refused to surrender.

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Problem Statement

For this project, we are to create a trebuchet to test in a competitive.  We are to have a

constructed trebuchet and have it prepared to launch on Monday, May 12. Our team devised a

problem statement:  Design and construct a launching device to maximize the horizontal

displacement of an bean, with size restraints and a $50 budget.  We created what we believed to

be the most efficient and successful trebuchet.

Proposed Problem and Design Specifications

 The most important criteria for our design are the following:

Can be constructed in the fabrication shop

Budget must be under $50

Maximum size can be 2 x 2 foot base, 3 feet height

 The class has to be able to use the resources available.  If the product cannot be built in the

fabrication shop, we have no place to build the product.  We are allotted only $50 to build the

trebuchet, and therefore cannot overspend.  The product size must be as specified for storage

purposes.  If it exceeds the size limits, it can be disqualified from the competition.

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Project Management

Communication strategies and time management were laid out in order to accomplish the tasks at

hand.  The task outline created from the given schedule was converted into both a PERT chart

and a Gantt chart to calculate total time needed to complete the project.  This plan allowed us to

set deadlines and have the initial design ready for April 20, 2014.

Define the working goals

For this activity, my teammates and I will design and construct a model trebuchet from

the given materials. Using a base set of plans, we will make design modifications to improve the

performance of the device. Our goal is to design a machine that will throw a bean the farthest

with the most precision.

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Selection

To start concept generation, we researched the different types of trebuchets and found

that there are four types:  fixed counterweight with fixed frame, swinging counterweight, floating

arm, and fixed counterweight with a floating frame. After we had the decisions made, we were

able to start designs a floating arm trebuchet and continue the design process.

After our design was finalized, we determined an approximate budget

PVC plumbing piping $23

Sling $5

Others 7

Final Total $35

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Detailed Design and Reflection

Our final design is a floating arm trebuchet.  This type of launching device uses the

energy of a raised counterweight to throw the projectile. Initially, the sling, which has a pouch

containing the projectile, is placed in a trough below the axle, which supports the beam. Upon

releasing the trigger, the sling and the beam swing around toward the vertical position, where

one end of the sling releases, opening the pouch and propelling the projectile towards the target.

The efficiency of the transfer of the stored energy of the counterweight to the projectile can be

quite high, even without, for example, restraining the path of the counterweight.

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Construction Report

Multiple problems occurred within the construction process.  First, every piece of our

PVP does not fit together, etc. The trebuchet started the first launch by shooting straight into the

ground several feet in front of the trebuchet. We had slightly adjusted the angle of the holding

the release mechanism to help allow the pin to slide more smoothly during the release.  Our

trebuchet started out really well.

There was some sort of error with the sling.  The bean was either shooting straight up or

rolling out of the sling.  We tightened the string on the net to help the sling hold onto the bean

more effectively.  The last change we made to the sling was adjusting the length of the strings for

the release.  By cutting them the slightest bit shorter, we were able to ensure that they were equal

in length to help create a more balanced and well-rounded release. 

Trebuchet Project April 14-20 April 21 28 April 28- May 4 May 5-11ResearchBrainstormConstuctuiontestalterationPaperwork

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Gather data and results

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Improvement

Trebuchets vary in their design. Some have wheels while others do not, and the types of

slings and counterweights vary, as well.

Trebuchets with wheels have an advantage because wheel-less trebuchets have the

tendency to rear up into the air as its arm begins to spin, and then slam back down. This

monstrous lurch can destroy the trebuchet. Rolling wheels prevent the crushing lurch by allowing

the energy to channel smoothly into the trebuchet's arm and missile. Also, wheels add power as

the trebuchet rolls forward. The forward motion adds velocity to the pitched weight.

Slings vary as well, and affect the trajectory of the missile. At the time of launching, the

sling moves faster than the beam, creating a whipping motion. A faster flung stone will deliver a

stronger punch to the wall. However, if a sling is used to extend the range of a trebuchet, a

lighter ball must be used to reach the wall, and delivers less destructive power.

One of the key design improvements was in the design of the counterweight. It is

believed that lead sheets were melted down and then attached to the counterweight of the

trebuchet. The lead attached is estimated to have weighed about six and a half tons.

The most efficient way for any counterweight to respond to the force of gravity is by

falling in a straight line. The hinged counterweight was developed, which allowed for a straighter

descent to the ground, providing the trebuchet—and eventually the launched missile—with an

even more devastating power.

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The types of missiles also varied. In addition to flinging rocks against walls, corpses were

flung into castles in order to spread diseases.

OUR TREBUCHET!!!!!!!

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Work Cited

http://www.historynet.com/weaponry-the-trebuchet.htm

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Trebuchet.html

http://en.wikipedia.org/wiki/Trebuchet

http://www.ancientfortresses.org/trebuchet.htm

"Trebuchet Types." Trebuchet Types. Tantaurus, n.d. Web. 18 Apr. 2013.

Parachute Cord. Michael's. Web. 19 Apr. 2013.

"Natural Burlap Fabric Sheet Size: 22" X 35"" Table and Shelf Decorations. Factory Direct

Craft. Web. 19 Apr. 2013.

Floating Arm Trebuchet, the Most Effecient Catapult! Perf. TeamCatapult. YouTube, 3 Apr.

2010. Web. 19 Apr. 2013.