Post on 26-Dec-2015
description
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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.