(ENG1001) Project 2 Brief - Trebuchet Design (on-campus) PDF

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ENG1001–LIGHTER, FASTER, STRONGER assignment...

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ENG1001–LIGHTER, FASTER, STRONGER PROJECT 2: TREBUCHET

SUMMARY Welcome to your second major project for ENG1001. You will be working in the same teams as Project 1. Your task is to build and modify a model trebuchet, with the goal of producing the best possible design to fulfil the tender outlined in this document. By understanding and optimising the dynamics of this mechanical system, teams should be able to confidently shoot over the range of distances required with high accuracy, repeatability, and power. ●

You will be building a trebuchet from a kit, which is stored in a container. It is your responsibility to take your container with you, and to bring it to your lab classes each week.

●

You can make any modifications to the trebuchet that you wish, as long as they are only made from the items in your kit, and the modifications do not break any of the rules listed in this document. You will be completing a risk assessment to ensure you can operate the trebuchet safely.

● ● ● ● ● ●

You will be taking testing data of the range your trebuchet achieves with a variety of different combinations of variables. You will obtain the statistics of your testing data to quantify its accuracy and repeatability. You will make necessary modifications to the model trebuchet to improve its performance. You will then use the data obtained for your final trebuchet build to participate in a trebuchet competition in week 11, where the objective is to knock down stacks of cups. Each team is required to submit a single page poster and a video of their oral presentation on the poster.

The assessment will consist of a video (4%) + poster (4%) presentation, trebuchet competition (2.5%), labs (4.5%) and teamwork activities (risk assessment + poster activity) (2%).

ENG1001: Lighter, Faster, Stronger Page 1 Project 2 Brief

CONTENTS SUMMARY

1

1

TENDER / PROJECT INTRODUCTION

3

2

MATERIALS AND EQUIPMENT

4

3

OCCUPATIONAL HEALTH AND SAFETY

5

4

TREBUCHET SPECIFICATIONS

6

5

COMPETITION RULES

7

6

POSTER REQUIREMENTS AND VIDEO PRESENTATION

8

7

ASSESSMENT SCHEDULE: LABS AND TEAMWORK ACTIVITIES

9

8

ASSESSMENT BREAKDOWN

10

9

PEER ASSESSMENT

10

APPENDIX: ADDITIONAL RESOURCES

ENG1001: Lighter, Faster, Stronger Page 2 Project 2 Brief

11

1

TENDER / PROJECT INTRODUCTION

LFS Demolitionists is an engineering company based in south east Melbourne, specialising in the deconstruction and demolishing of various types of structures. In the interests of generating a new source of revenue for the company, they are looking into producing a television program, made up of footage of their work. In order to make the show more entertaining, LFS is looking into new and interesting methods of destruction. Or, in this case, a very old and interesting method of destruction: a trebuchet! The intention is to set up a trebuchet in a certain location, and then demolish a series of small structures at varying ranges in a single direction. This would be achieved by slightly altering the trebuchet set up to produce the desired range changes, without relying heavily on the projectile bouncing into the target. LFS has hence put out a tender for budding design engineers to come up with a trebuchet design that will fit their circumstances. The trebuchet design is to be judged equally on the presentation given by the applicants, and on the performance of a scaled down prototype built by the applicants. The dimensions of the required scaled down set up is shown in figure 1.

Figure 1 Scaled down version of the setup for the trebuchet competition.

ENG1001: Lighter, Faster, Stronger Page 3 Project 2 Brief

2

2.1

2.2

MATERIALS AND EQUIPMENT Each team will be provided with a project kit that comes either in a bag/backpack. Locker will be provided; these are located on lower ground floor of the Woodside building. You will take this kit with you and return it in week 12. It is your responsibility not to lose the kit and to bring it to every practical class in the last 6 weeks of semester.

2.3

The kit and its contents must be returned in the Week 12 Lab. Very few of the items supplied in these kits are considered ‘consumables.’ Nearly all parts will need to be returned in good working condition, and these will be checked off by the demonstrators.

2.4

A cost will be incurred for any lost or damaged components. A price list will be provided on Moodle as well as in your week 7 lab for reference. Teams will be responsible for sharing or recouping these costs between members. The total kit value is over $300.

2.5

Teams should note that the trebuchet and even the projectiles must only be constructed from the supplied components, in the supplied quantities. Teams should ask the demonstrators if they run out of a consumable.

You are NOT allowed to add additional items or use non-standard items, unless otherwise stated. 2.6

Your trebuchet kit contains the following: Non-consumables: (must ALL be returned in good condition) ● ● ●

1 x Trebuchet Kit in a clear parts organiser (see Parts & Tool Templates) 1 x Tool Kit (see Tools Template) 1 x 20m Tape Measure

Consumables: (these items do not need to be returned) ● ●

0.5m of clear Fishing Line (to make slings, which will remain attached to the projectile) A small number of cable ties (return any unused ones please)

ENG1001: Lighter, Faster, Stronger Page 4 Project 2 Brief

Commented [1]: Are we just providing them with a bag instead? Update accordingly.

Commented [2]: Lockers will be provided students. These are located on LG of Woodside. I'm thinking of how to share the pins with them atm.

Commented [3]: Are we updating this?

3

OCCUPATIONAL HEALTH AND SAFETY

Good safety practices are of paramount importance in the Engineering profession, and they are applicable to you as students. Please exercise caution and common sense, particularly noting the following precautions. 3.1

The wire tip on the throwing arm on your trebuchet MUST always be rounded at its tip to reduce the risk of eye injuries. Teams may adjust the angle of this bend but MUST NOT change or modify the basic design. Spare wire can be supplied if you break or damage your tip.

3.2

Safety glasses MUST be worn at all times when testing or launching your trebuchet, or when in proximity to other teams launching theirs. Teams found not wearing their glasses will be warned once and, if they continue to do so, they will be penalised in their lab marks.

3.3

Students MUST wear closed shoes and proper attire when testing their trebuchets.

3.4

You MUST only use the supplied wooden balls as projectiles, along with the fishing line sling and eyelets for attachment. Nothing else should ever be launched from your trebuchet.

3.5

The only places on campus that you may fire the trebuchet are: Room 1.02, 1.10 Woodside Building (the practical class room) in your assigned lab session; and outside that session in an area in front of the Woodside Rapid Prototyping space (students need to set up traffic cones when firing).

3.6

You may also fire your trebuchet off-campus, away from other people, but you must do so safely and all team members must still wear safety glasses. Remember that all students are responsible for their own and other people’s safety, as well as for any property damages. You must exercise all preventive measures at all times.

3.7

Be careful not to get projectiles caught in the overhead power rigging in the rooms. If any do get stuck, they should be carefully retrieved by a member of staff using a pole. Please do not try to stand on the tables or anything else in order to reach them.

3.8

No food and drinks (except water) are permitted while testing any of the trebuchets. Teams will be held liable for any cleaning costs or damages.

ENG1001: Lighter, Faster, Stronger Page 5 Project 2 Brief

Commented [4]: Outside area in front of the Woodside Rapid Prototyping space (not sure of room number). Students to set up traffic cones when firing.

4

4.1

TREBUCHET SPECIFICATIONS

The trebuchet itself is to be built using only the components from the kit provided.

4.2 The wooden throwing arm and metal tip must be used as provided; however, the angle of the tip may be altered. 4.3

The counterweights must be used as provided. Teams may not use additional counterweights (more than 3), or use other parts as counterweights. No energy sources other than the counterweights provided are to be used to propel the projectile (e.g., additional springs or levers are banned).

4.4

The projectiles must be used as provided. Teams may not modify the projectiles in any way. Only one wooden ball may be launched at a time, or per shot. Please ensure that you do not remove the screw eyes affixed to the projectile. IF the screw eye on the projectile is loose, please request help from a demonstrator.

4.5

Teams may modify the assembly of the trebuchet support frame and arm from the instructions given to increase the range and/or improve its accuracy. Only the original parts (and spares) may be used in the support frame or arm.

4.6

For consistency, all slings must be made from the lightweight fishing line and swivels supplied. More line is available if you need it. Please ensure that you have enough tension in your knots to prevent the sling from loosening during launch. Up to THREE (3) SWIVELS may be provided per team to allow teams to pre-prepare the sling lengths required for the competition.

4.7

Teams are encouraged to use creative means and the components provided to improve the accuracy and range of their trebuchet, provided that the spirit of the rules is followed and the safety of the system and the firing action is maintained. If for any reason you are concerned that your device, or another team’s device, is unsafe or not in line with the rules please let your demonstrators know.

4.8

The unit lecturers and demonstrators have the final say with regards to the interpretation of the rules and reserve the right to change or amend them at any time, if required.

ENG1001: Lighter, Faster, Stronger Page 6 Project 2 Brief

5

COMPETITION RULES

5.1

Aim: knock down a pyramid formation of 10 empty 425ml or 450ml Redd’s plastic drinking cups.

5.2

The tower of cups (target) will be built on the A3 Target Template provided in your kit, which features the silhouette of the lowest four cups. This template will be taped to the target platform.

5.3

A cup is only considered to be knocked down if it is either:

5.4

1.

Knocked over, upside down, or off its usual stacked position, or;

2.

For any bottom level cups, if ANY part of the solid black circle silhouette on the target template is visible from directly overhead.

The set up for competition day is as follows: 1.

The target platform will be one of the standard tables in the rooms (Woodside 1.02 or 1.10), oriented with the longest side parallel to the firing direction. The target template, and hence the stack of cups/target, will be set up in the centre of this table.

2.

The launching platform will be one of the standard tables in the Woodside 1.02 or 1.10 rooms, oriented with the longest side parallel to the firing direction. The trebuchet may be freely positioned on this table, provided the trebuchet and projectile are completely within the plan (top) view of the launching platform when fully primed. The trebuchet may be repositioned between shots.

3.

The quoted distances on the day are measured as the closest distance between the launch and target (location of the cups). This will range from 2.5m to 8m, at an increment of 0.5m for the competition.

5.5

8 shots will be taken at each range. The target will be rebuilt after each shot is taken. Demonstrators will inspect the target before each shot.

5.6

A single team member must make all of the shots at each given range. Every team member must operate the trebuchet at least once.

5.7

The score for each shot is determined by the shot number (different weights), and the number of cups knocked over. The weightings of each shot are as follows: Shot # (at each range) Points per cup

1

2

3

4

5

6

7

8

Total points

2.8

2.2

1.7

1.4

1.2

1.1

1.1

1.0

125

5.8

A total of four different ranges will be tested. The first range is set at 2.5m and the last range is at 8m, teams will be informed of the remaining two ranges (between 2.5m and 8m) at the start of each competition heat.

5.9

At the start of the competition session, teams will be given 10 minutes to set-up and calibrate their trebuchets. No test shots will be provided.

5.10 Between shots, teams will have about 1-2 minutes to make fine adjustments whilst the demonstrators record the scores, before the next shot countdown commences. 5.11 Between ranges, teams will be given about 5 minutes to adjust their trebuchets. ENG1001: Lighter, Faster, Stronger Page 7 Project 2 Brief

Commented [5]: Happy to leave it as is if you're comfortable with this given the space and time.

6

POSTER REQUIREMENTS AND VIDEO PRESENTATION

The Trebuchet Project Posters will be submitted by teams and presented to/assessed by demonstrators in the allocated labs in week 12. The poster will serve as a business/project tender where teams will need to convince the panel that their trebuchet is the best design amongst the cohort for the LFS Demolitionists scenario. Note: i.

ii. iii. iv.

Posters must be done in a single slide of PowerPoints presentation in full colour, to be submitted (as a single page pdf file) with a presentation video. A PowerPoints template with the correct paper size will be provided through Moodle. The video presentation time limit is 7 minutes. All team members must present in the video. Consider the limitation of a laptop screen, in your video presentation, multiple slides can be used to present different elements of your poster. For submission: a single page pdf file of your poster and a 7 minutes video presentation on your poster to pitch your design to LFS Demolitionists.

The posters will need to contain at least the following sections and content: Introduction

Theory

Description of the project / tender. Include project restrictions such as height and material. Brief outline explaining the theories governing the motions in this system. Explain what is being optimised / improved in this system. Briefly justify the theories behind all design modifications made. Explain the initial data collection procedure.

Testing methods

Explain how the team approached optimising the trebuchet’s performance. Points will be awarded for logical and coherent experimental / testing methods. Pictures describing all interesting design features or modifications made to the trebuchet from the original design to improve the system’s performance.

Trebuchet design highlights

Graphical summary of trebuchet range and variability for different settings

Teams must be able to explain the reasons and theory behind the modifications when interviewed by the demonstrators. It is insufficient to just mention what the changes are. Graph(s) indicating how teams interpolate and predict necessary variable combinations required to hit ANY given range for the final trebuchet design. Using only the information read directly from this graph(s), teams must explain how the best trebuchet settings can be inferred for any target range between the minimum and maximum required by the competition. Show the range variability of the ranges through the use of vertical error bars set to +/- 1 standard deviation. Conclusion to summarise the trebuchet design – why it works, why this design is better that the other teams’ design.

Proof of concept Proof of performance / proof of concept – include score and number of cups obtained in the competition. Justify why your team should win this competition. ENG1001: Lighter, Faster, Stronger Page 8 Project 2 Brief

Commented [6]: Should we mention that a template will be provided? Commented [7]: Do we provide resources on how students can do this?

7

ASSESSMENT SCHEDULE: LABS AND TEAMWORK ACTIVITIES

There are 3 labs and 2 teamwork activities to be completed for this part of the course. The lab worksheets can be downloaded from Moodle and to be completed collaboratively through Google shared drive. Each team is to complete a single lab worksheet. This will only be marked in the lab session in the correct week. You will need to be in attendance for these practicals to receive these marks. Team members absent for the labs or the final poster presentation (in video) without special consideration will receive 0 mark for each component respectively. Note that the practicals commence on the hour in line with university regulations. Late attendance may be penalised. The schedule for these assessments is as follows: WEEK

LAB ASSESSMENT

TEAMWORK ACTIVITY

7

Receive trebuchet kits.

Risk assessment

8

Trebuchet variable testing lab

-

9

Projectile motion lab

Poster design

Energy method lab

-

10 11

Trebuchet competition

12

Submission of a poster pdf file and a video of your presentation through Moodle. Return trebuchet kits in your lab session.

ENG1001: Lighter, Faster, Stronger Page 9 Project 2 Brief

8

ASSESSMENT BREAKDOWN

This project carries 17% of the total final marks for this unit. The breakdown of the unadjusted final marks are as follows: COMPETITION POSTER

Trebuchet competition

2.5 %

Poster and video presentation

4% + 4%

Lab work

4.5 %

Teamwork activities

2%

PORTFOLIO TOTAL

17 %

The relative score from the trebuchet competition will be determined through a statistical analysis of the scores from the entire class. Teams whose total score: ● ● ●

is more than n standard deviations below the mean will receive 0.5/2.5. is more than n standard deviations above the mean will receive 2.5/2.5. lies between these two values will receive a score based on a linear scale between the above point limits. This means teams scoring exactly the mean will receive 1.5/2.5.

To give you a rough idea, the statistics obtained from a previous semester are min score = 22 p...