ENGINEERING 10 TREBUCHET PROJECTBy HL and TC

Blk. 2

Introduction

Description:

Students will use the design cycle to create a functioning Trebuchet that is capable of throwing an object with repeated accuracy. (25 feet, 5 consecutive times).

Learning Outcomes

-Work collaboratively in a team

-learn about historical significance of the trebuchet

-Understand basic principles and functions behind the trebuchet

Statement of Inquiry:

Historical technical innovation has contributed to advances in modern human process.

Global Concepts

Scientific and technical innovation

Materials Provided

Wood ( 36 by 12 inches)

Lead counterweight

Various screws, bolts etc.

Sling fabric, plastic wheels

INVESTIGATION

Inquiry questions

At the start of this project, we were given time to research info about the trebuchet and brainstorm possible designs. We then researched potential trebuchet designs to create; evaluating each on its characteristics or pros/cons

What materials are needed

What are some common issues/problems

What does it mean to be proportionate

What is the recommended size

How much counterweight is needed

What type of wood is used

How far should the distance be

What are we throwing

How much time is required

How do we attach the components

What are the components

What type of trebuchet are we building

What calculations are required

What is an effective planning method

We also had to familiarize with basic physics concepts as well Definition/purpose- A trebuchet is

a battle machine used in the middle ages to throw heavy payloads at enemies. The payload could be thrown a far distance and do considerable damage, either by smashing down walls or striking the enemy while inside their stronghold.

Where- Ancient China, then /Europe/ Middle east

What replaced Trebuchets?- The Cannon

Ex. Torsion, lever arms, moment, momentum, force, potential energy, kinetic energy, arm ratios.

These concepts had to be understood in order to design a fully functioning trebuchet.

Prior to brainstorming designs, we were unfamiliar with the Etymology of the trebuchet, therefore we researchedThe 5ws of it

Design

To answer our inquiry questions, we conducted researchOn the trebuchet, and what designs might inspire us.

There were 4 types we could choose from.

Swinging Counterweight-weight is looseWeight falls vertically

Fixed counterweight on a fixed frame-weight is fixed-Weight hits base to fling object

F.C on a floating Frame-fixed weight-allows weight to fall through the frame

Floating Arm (FAT)-weight falls, causing one part of arm to fall, and other to swing up

Design

DesignWe came up with three designs after researching various models

Fixed Counterweight with Floating frame-Had wheels to absorb recoil and use it to increase thrust. However object had to be attached to a sling as well as balancing the counterweight with the arm size, therefore making it difficult to shoot without calculations

Fixed free swing counterweight- This model would allow the object- To be shot in a catapult launch method.- However the object would not go far due to the size ratio.- This trebuchet type is unique,- as the bigger the object is, the farther it can throw.

Design

In the end we chose the fixed counterweight on a fixed frame.

This model has wheels the frame could surge back and forth by a small amount, allowing the counterweight to fall more vertically.Secondly, the recoil force absorbed by the wheels could throw the object farther.

Our good copy design sketch of our chosen design

Although this type of trebuchet usually has a firing pin that pulls out of the Frame to fire, we decided to use a string ties to a hook to create an elastic type of launch sequence.

Plan After creating a blueprint for our project, we created a concise plan to help us build efficiently.

Goals of the team

We plan to finish the trebuchet by Jan 21st; the final deadline for construction.

Utilizing any remaining time and resources to add final tweaks and adjustments.

The PPT will be finished by Jan 21st, after construction is complete, and the trebuchet has been test fired. Until we reach

those deadlines though, we will begin a steady construction process of both these

Assignments simultaneously. Adding/removing info based on results.

Roles of the team

-Tyler-building-Hoya- Design brief/building

PLAN

Strategies Used: 1. Be industrious and diligent during work time. 2. Make sure each group member fulfills their role. Make sure the final product is in full working order to compete. 3. Calculate amount of resources needed and how to use them

wisely. 4.Take risks and look for new effective ways to improve the product. No matter how exotic the process. 5. If we make a mistake during construction, we stop and refine

before considering Anything else. 6. Teamwork and cooperation are essential for creating a

successful project.

SCHEDULE/MANUAL (BY RELEVANCE)

Cut out wood pieces after measuring

Verify that all pieces are compatible with each other

Build the horizontal and vertical frame. Nail pieces together.

Add Gussets to strengthen edges and frames. Nail gussets after gluing.

Cut out plastic wheels

Trim out ready-rod for arm, attach wheels with screws.

Calculate arm ratios and strength, then attach to frame.

Attach Sling with firing pin

Attach counterweight

Test fire (using different counterweights)

Finish research assignments done in class.

Start the investigation process, research types and pros/cons.

Create multiple designs, then decide on the most feasible.

Create a Blueprint/good-copy sketch.

Write down design process

Create a Plan including schedule and goals/roles of the team.

List Creation Process step by step

Take pictures of creation process

Evaluate by test firing.

Plan

Building Design Brief

CREATEHoya Tyler

Sanding, refining/assisting.

Cutting and Drilling

After cutting out the required pieces, we can begin construction on the frame.

We create the horizontal base first, then begin the vertical frame.

Part 1# Assembly

We plan to create the design exactly how we pictured it in the planning stage. Considering its pros and cons and evaluating them based on potential positive or negative results.

PART 2# STRENGTHENING/REFINING

After creating the frame, we measured and cut out a dozen triangles of thin wood to use a s gussets. Gussets would help stabilize the frames and angles, thus prevent the frame from becoming loose.

Part 3# Arm and WheelsWhen the frame was sturdy enough, we attached a ready-rod to hold the arm in place. Our arm wasn't a straight piece of wood, but consisted of 4 different pieces.

Two pieces were added to stabilize the arm at the revolving point to equalize the weight and prevent the arm from snapping.

-Once the arm was done, we cut out 4 plastic wheels approx. 10cm in diameter to absorb the recoil of the trebuchet when firing.

We used a ¼ ratio for our arm. Our arm was approx. 25 inches in length

PART 4# SLING AND WEIGHTS

In the end, we used two large weights instead of one.

Now that the initial structure of the trebuchet was finished, we could begin sling and weight assembly. We used a square piece of fabric approx. 15cm by 10cm as the pouch. Secondly, we tied the pouch to the arm with a thin string.

Thirdly, we made a firing pin out of a string and a hook that was released by pulling on it. Therefore releasing the arm.

(The idea of a string firing pin was to give the arm an almost elastic type of force instead of relying on the removal of a rod pin to increase centrifugal force.)

EVALUATION OF FINAL PRODUCT

Test /firing results (Approx.)

First time- 10ftSecond time- 15ftThird time- 27ftFourth time -18ftFifth time-15ft

Average of 17ft/five consecutive tries

The reason for the large difference in distance was due to the loosening of the sling. The sling should have been larger and the string should ha been tighter. In other words, the Movement and arrangement of the string and sling (which was different each time) resulted in a Different firing trajectory.

EVALUATION (TYLER)

Overall, I am happy with our final product in terms of structure and resource use. We effectively utilized all resources to create the trebuchet. ( we even had leftover wood). We managed to complete the trebuchet and test it before the deadline but we didn’t have enough time to make modifications or improvements. The string and sling were not accurately assembled, which resulted in the inaccurate results of firing. I feel that I could have done a better job in measuring and testing parts such as the sling before permanently attaching them to the trebuchet. In the future, I plan to do 100% checkups on each part before proceeding to the next.

EVALUATION (HOYA)

In the end, I am proud of our final product and the ways we used our resources and time. We made good use of every resource to make sure we didn’t over over-budget, and we worked on regular basis every class to consistently improve the trebuchet. Our firing results were a bit disappointing due to the odd pattern results. We had figured out a solution to the problem, but we had run out of time and had to reflect on the process we had managed to make. My role was to assist in the crating process any way I could, and to successfully complete the required design brief. I am satisfied with my role in the design brief as I went in depth of all factors and concept prior, during, and after the construction process. However, I wasn't very effective with my time as I did not get to complete the reflection process in time with the project. Our trebuchet was tested at the final day and I did not get to submit any possible improvements for the brief. For future projects, I intend to keep a tight schedule for our process. This included taking time time out of our own day if we didn't’t finish the required materials for that specific date. I feel that if I had done that, we would have had time to make any necessary improvements to create the best final product, as well as competing the brief in sync with the construction.

TEAM EVALUATION Our team managed to successfully complete the Trebuchet by the deadline, along

with the Brief. Each team member contributed equally to the project to enable a successful final product.

The trebuchet itself is in perfect working order. It is easy to use with a simple firing mechanism which included advanced firing physics. (Elastic Theory). Our wheels worked fabulously as they transferred the recoil into momentum energy.

On the contrary, we did have a significant problem. Our sling was not the right size for the tennis ball we were throwing. It was too large for the ball, therefore causing it to slip around when it fired. We figured this was the reason for the odd pattern of distances.

Secondly, the string was very thin and often entangled with the trebuchet, delaying firing and causing confusion.

Our Solution to these problems were to accurately measure out a sling proportionate to the object being thrown as well as using tighter stronger wiring for the arm. We feel that we would have had a perfect work schedule and product if we tested/measured all materials prior to permanent attachment. Doing so would help us create the best product as well as leave time for improvements and reflection.

In term of competition, our trebuchet was average, but we could have done better if we had time to make modifications.

Our work ethic and knowledge of shop materials mainly contributed to our success in creating the project. Each team member did an excellent job of fulfilling their role. We worked hard every class and it sped up the process. In the future we should accurately measure and test all materials in sync with deadlines to prevent problems and to effectively reflect on the project for any improvements.

BIB

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"Main Page." Wikipedia. Wikimedia Foundation. Web. 17 Jan. 2015. <http://en.wikipedia.org/wiki/Main_Page>.

"Trebuchet." Trebuchet. Web. 25 Jan. 2015. <https://www.msu.edu/~hartle35/KHweb/webquest/WebQuest Stuff/Trebuchet.html>.

"Trebuchet Physics." Real World Physics Problems. Web. 25 Jan. 2015. <http://www.real-world-physics-problems.com/trebuchet-physics.html>.

"Trebuchet Types." Trebuchet Types. Web. 25 Jan. 2015. <http://tantaurus.net/trebuchet/php/trebtypes.php>.