Murlin Trebuchet Case Study

Murlin Trebuchet

SUMMARY
Murlin Tebuchets are lightweight, transportable, and very efficient.  The advantage of that is that you can fling a projectile far distances using very little counterweight.  This project is an engineering masterpiece and that is why I want to work on it.

CASE STUDY #1
Rating (7 /10)

Diagram of Murlin Trebuchet
http://www.behance.net/gallery/The-Murlin-Trebuchet/10601767

 Positives:

• It has a video, step by step
• Many, many photographs

Negatives:

• Dimensions are vague
• No specification of hardware (pulleys, bearings, release pins, firing mechanisms)
• No (Content) Most important Dimensions, weights, mass ratio and range are not given in text.
• You have to watch the video to know how to build it

http://www.behance.net/gallery/The-Murlin-Trebuchet/10601767

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CASE STUDY #2Rating (10 /10)

Diagram of Murlin Trebuchet
https://etown.digication.com/kaylee_werner/Trebuchet_Project

 

Positives:

• It has a video, step by step
• Many, many photographs
• Dimensions are vague
• Specification of hardware (pulleys, bearings, release pins, firing mechanisms)
• (Content) Most important Dimensions, weights, mass ratio and range are given in text.
• Results shown

Negatives:

• None

https://etown.digication.com/kaylee_werner/Trebuchet_Project

 

 

 

 

 

SumoBot

Sumobot

Mike Desmond

Winning bot

Our bot

Our bot

The project requirements were to build a robot vehicle that can have a brain attached to it that will be able to make it around a course in the hallways.  It had to be as fast as possible to beat other teams and had to be precisely crafted in order to maintain stability and accurate steering.  We chose to mount the motors and wheels at the end of the given wood piece, and the roller bearing wheel in the front with the brain and batteries in the middle.  This would give us the option to have either side the front, so we could experiment which was better - for the powered wheels to push the rest of the bot, or for he wheels to pull the rest along.  Groups 1 and 2 finished, but not groups 3, 4, and 5.  Group 1 was 2:24 and group 2 was 2:50.  The overall winning bot was very fast because it had a wide wheelbase, was assembled carefully, and had a great gear system.  Unfortunately, our group's bot was unable to make it around the track since it couldn't go very fast, and couldn't go straight or left because it kept going right.  What I would do to improve this would be to get smaller wheels, maybe add a gear system, and possibly make the rear wider so that the weight can be placed on the wheels.

Fastener

Art Structure

Mike Desmond

 

Rubber Band Fastener

Our groups design

Our fastener was the rubber band.  We designed and layed out the structure with the pieces, and then designed how we would connect and hold everything together.  We made up a system where we cut grooves in the sides of the wood where the rubber bands would hold, so that they would stay in place.  The rubber bands would hold the pieces of wood together, and the rubber bands would be held in place by the grooves.  When we noticed weak spots, we added more rubber bands to increase the strength and hold the structure together more securely.  Sean's idea was to make a field goal post, so we designed it.  We experimented with the structure so that it could be held together in the most secure way, and finished pretty quickly.  We could've worked more to make it more advanced but had no more ideas and the rubber bands limited our creations.

Build a Compound Machine

Build a Compound Machine

Mike Desmond

 

Our machine that we built

We combined and transformed our four simple machines to create a massive machine that would give us the ultimate mechanical advantage.  We put the lever on top of the pulley frame so that we could attach the wheel and axle to pull down the lever.  At first, the pulley system did not do anything.  But then, we incorporated the pulley system by having the string pull down the pulley, and secured the second pulley to the bottom of the base.

The project turned out great and we were in the lead.  Other groups followed our idea of this and took the ideas themselves.  The string was falling off of the wheels so we added another axle to correct this and guide the string to go straight onto the wheels.  We also extended the arm of the wheel and axle multiple times.  Our methods were very successful and it turned out to work perfectly.  We achieved the highest mechanical advantage in the class.

We learned that it would be easier to plan it all out in the beginning so that we can modify all of the parts before-hand instead of having to take apart many things.  There were no surprises in this project.   I could definetely use this knowledge for future projects.  I found it very easy and creative to build simple items, like our four simple machines, and then combine them to make something very cool.  This machine turned into a piece of art and it was a pleasure making it.

Simple Machines

Four Simple Machines

Mike Desmond

 

 

We built a lever, wheel and axle, and inclined plane, to a mechanical advantage of 6, so that we could demonstrate how much they help us to make everyday work easier.  The pulley that we designed had to have a mechanical advantage of 2.  To calculate the % efficiency we did the Actual Mechanical Advantage divided by the Ideal Mechanical Advantage, and then multiplied by 100.

                            Lever by our group                                 Inclined Plane by our group


Pulley by our group

Wheel and Axle by our group



 

 For the Wheel and Axle, we tied for third place, with about 70% efficiency.  For the Inclined Plane, we came in 5th with 33.33%.  On the Lever we had a 66.67% efficiency, which made us come in second because everyone else was diqualified.  On the pulley we had 64.79% efficiency, which landed us last place, but when Mr. Adkins measured everyone's projects to see if their measurements were off, and many groups except ours exceeded the qualifications so they were considered cheating.  That was what also made it difficult to determine the placement of the teams, because you have to tell if the machine was built correctly and was within the guidelines.

We were pretty far from 100% efficiency each time.  This was because our measurements weren't precise enough and we didn't have the most precise tools to be able to build a machine that well.  Another reason is because we did not factor in friction with this.  One more reason why we didn't achieve 100% efficiency was because testing the machines was difficult and not accurate at all.  Unfortunately, there was really no better way to test our designs.  If we made our machines on a bigger scale it would've been easier to be more precise, but that would've also taken up more time and costs for the larger materials.

 

 

 

 

 

 

 

 

 

 

 

 





Reducing Six Simple Machines to Four

Reducing Six Simple Machines to Four

• Pulley
• Wheel and axle
• Lever
• Wedge
• Screw
• Inclined plane

How we can reduce to four:

There is no need for a wedge, since we already have an inclined plane which is basically the same thing, and we don't need a wheel and axle since the pulley includes that. The screw is just an inclined plane wrapped around a point.

Mike Desmond
Brainstorm

Project Ideas:
Use an Emotiv to control typing on a computer so it would be much faster
Use an Arduino TRE to detect snow on the roof of a car and turn on a heater to melt it.
Use an Arduino TRE to detect a breeze when someone walks in a room to turn on the lights
Use an Emotiv to open your lock when you are near
Use an Arduino to sense when there is an increase in sawdust and turn on the vacuum fan