Murlin Trebuchets Case Studies

Finbarr Saunders
May 13, 2014

Summary:

The Murlin Trebuchet works by a string, attached to a counterweight, is wrapped around the prongs that are attached to the fulcrum. When the weight drops it pulls the prongs and on the last prong is a sling with a projectile.  On part of the sling releases at a certain angle while its rotating around the fulcrum throwing the projectile into the air.  I would like to work on this because its a difficult challenge that will take a lot of effort into the building and designing to make it the most efficient machine possible with the most mechanical advantage.  It's unique because the unlike a normal trebuchet this one drops a counterweight straight down and not using a normal force and resistance arms. These arms are going to be changing within the process of launching the projectile.

Case Study #1

Rating - (7/10)

http://www.instructables.com/id/The-Marshmallow-Trebuchet/#step0

Positives:

1. It has the history of this trebuchet.
2. There are available pictures used in the website.
3. It has ways to improve your design.
4. It has the materials used.

Negatives:

1. No dimensions.
2. Different projectile than what we are using in class and different weight used.

Case Study #2

Rating - (6/10)

http://prezi.com/lpxzueiilmh2/murlin-trebuchet/

Positives:

1. Includes dimensions and sizes to help configure to our preference as a group.
2. Labeled blueprints to help with how to build the trebuchet.
3. Includes useful info withour having to research many sites, the background information

Negatives:

1. Too lengthy and gets annoying for reading it for a long time.

Faster Blog

In the Faster Lab my group of Zach, Morris and I had to use wooden pegs as a faster.  Our design was going for  hovering house or a beach house that's being held up by pegs.  It was a very difficult because it took a while to get all the holes to line up with the right size holes.  While in the process of building the sculpture the group hit a setback when a piece of the wood snapped in two places which then we realized we had to use smaller pegs unless the wood would snap again. So we had to re-drill every hole to fit the newly sized pegs.  Then we had to re-line up the holes and made sure they were the right size in one class period.  The final thing was not the way we had planned it to look like because it had multiple useless holes where we messed up.  It was very difficult to portray a house like that with the limited amount of materials.

Compound Machines

 

After the simple machines were complete we were give the new task of combining the simple machines into one compound machine.  instead of trying for a mechanical advantage of 6 the goal was to obtain the largest mechanical advangtage possible.

We decided to use the pulley, the wheel and axil, and the lever. We were not allowed to use the incline plane. This was the opposite of when we were building the simple machines because we are not going for the AMA of 6. After many tries we were able to come up with a simple idea on how to get a high AMA. We were able to get an AMA of 39 witch mean we got a B+. I wasn’t too worried about the other groups because I really was only competing agents myself to get the best grade I could. But at the same time the way other groups combined their machines intimidated me to do better. Some of the other groups were recording massive amounts of mechanical advantages that completely surpassed our groups' final result.  We had a problem with finding the right place for the pulley to combine with the lever. We fixed this by combining them in different places and testing them to see which placement had the best AMA for is machine. Are methods were not the best but they worked out in the end. We could have spent more time on it rather than talking to other groups and getting distracted.

I learned that you can combine small machines to create one machine that could perform almost 50 times better than just one machine. It was very difficult to decide how we were going to place each machine and combined them for the best AMA. I was surprised to see how easy it was to move the hole machine to lift the wait. WE could take this project and combined it to are trebuchet to make it move quicker and have more accuracy.