Reflection on Test day #4

Part 1

In the accuracy part of the challenge project we got off to a super bumy start. The first shot of ours went backwards, along with our second. This left us with one more shot to try and record an accuracy mark, and it came threw when we needed it to with an accuracy marking of 1.60 meters. We were absolutely thrilled with this because this was the best that we had ever gotten it to shoot to 15 meters. Even though this placed us last in our class for rankings, I was just glad that we were relatively close. If we had the chance to modify our current trebuchet design I would want to make our trigger system apparatus alot stronger, because it seemed as though that gave us some troubles. If we were able to start with a brand new modely I would for sure go with a non-fixed weight, just because that seemed to be alot easier to play around with ( viewing from other groups) rather than having to adjust the sling length, arm length and all of that stuff etc. It would also be of interest to me to make a smaller base and therefore add more height onto the trebuchet, for the fact that the taller it is the longer the distance it will shoot. The only thing that I really would've wanted to tweak with on our current model, would've been the pouch. You pretty much need a perfect pouch if you're wanting to get a somewhat consistent shot.

Part 2

From the start of the Trebuchet Challenge I didn't know how keen I would be on doing something like this. The papermodel is where I got extremely frustrated, but I'm glad that we were made to do a mini one, because I think if we just jumped straight into the big design there would be a million questions and alot of anger. In the end I really did enjoy doing such a hands on project. Some of the things that went well for Karissa and I driung the project were:

- the durability of the big model

- our cooperation with eachother

- some different materials that we used rather than the same old thing

 

There's so many things that you could recommend to future classes. But the three main things that I would suggest, would be to have as small as a base as you can so you can have achieve a maximum height. We built ours this way and so did all of my class mates and it seemed to be to our benefit. The second big thing would to have a non-fixed counterweight. It's much more easier to play around with the weight, and then once you feel as though you have your spots you can simply mark down the amounts you used. It's a bit harder using a fixed weight ( what we did) because it was complicating on what we were going to mark in order for us to know our key spots. Lastly I would recommend a very strong and consistent trigger system. You may think that you want to try a complex system, but in reality the easiest ones work just as good!

Reflection on Test day #3

Part 3

To calculate the theoretical range you use the following formula: 2*h* (M/m)
H- stands for the heights that the bucket falls in meters
M- the weight you use (counterweight)
m- the weight of the tennis ball

2*(0.98 m)*(22.6796 kg/ 0.0624 kg) = 712.37 meters
After we got all of our weights and measurements we came up with a theoretical range of 712.
37 meters for our trebuchet. This is obviously a drastic comparison to our average distance that we were shooting of 23.44 meters. There are multiple reasons why I think our trebuchet didn't perform as well as it could've. On our launch day we defintely had murphy there with us! The biggest reason in my mind why it maybe didn't shoot as far would be the angle of release. The nail seemed to be loose and kept wiggling on us, therefore when we went to hammer it in it got slightly changed which can make a big difference. Our arm was another big problem for us. The arm randomly broke off for us after our 3rd throw which meant that in order for us to have an arm we had to shorten it which affected the distance. It was much easier having a fixed weight in the sense that you weren't constantly changing things, but it did make it a bit harder to shoot farther since we couldnt add any weight. I think if we would've added even 25 pounds we wouldve got an extra 10 meters out of it. We saw this in our mini model with the washers, that the more weight you have the farther it seems to go. Another thing that worked in our favour sometimes and other times not was the pouch. I think that if we would've spent more time on that part of the project we wouldn't have had the problem of the ball staying in the pouch or rolling out. Lastly, an even longer length for our pouch strings would've been beneficial, because gravity would've had more time to play its' role of force on it.

Ready to let the trigger system release

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Part 4 

On the day of our trebuchet challenge we began with a 10 minute time frame where we were able to set everything up and make any minor adjustments. After the 10 minutes was up we got 20 minutes to launch 5 times to try and achieve an average of 25 for full marks. Our launches were marked at the following distances:

Launch 1- 20.2 meters

Launch 2- 25.8 meters

Launch 3- 43.6 meters

Launch 4- 0.00 meters

Launch 5- 27.6 meters

After we completed the launches this gave us an average of 23.44 meters. We were happy with all of the distances that our trebuchet shot, other than the 0 meters. The ball not shooting at all made it that much harder for us to try and get a 25 meter average. Overall I was pleased with how it ended up working for us.

The things that we had planned, and did change for the accuracy part of our trebuchet was the arm length, sling length and the angle of release. We shortened both the length of the arm and sling so that there was less time for gravity to effect the ball. The change of the angle of release was almost 60 degrees rather than 45 so that it would shoot higher up rather than farther across. In the end most of our adjustments paid off.

Trebuchet

March 29th was test day for our trebuchet's. We got off to a bit of a shaky start with a few launches going backwards, but after some tweeking we exceeded to shoot on average a distance of 40 meters. This was a big relief for us knowing that we don't have to change anything for our distance. We ran out of time to work with the accuracy part, but plan to do so over the weekend. It's clear since we have a fixed weight that we're going to have to do some major adjusting with our pouch, string length and arm length. We are looking forward to test day and hope to achieve both the accuracy and distance.

Karissa and I with our baby on test day

Paper Model Trebuchet

   Our trebuchet challenge experience began with us being paired off into groups of 2. After this it consisted of us getting pieces of paper with cutouts that we had to assemble to make the small paper model. This took several hours for Karissa and I making sure that it was solidly put together and there would be no pieces causing friction. The trebuchet had to hurl a distance of 10m using a little wooden ball and washers acting as our counterweight. Since the marble was a projectile and it was dealing with no other forces other than gravity we really found that we had to tweak our angle of release in order for it to shoot the way we wanted it. We were quite frustrated off the start seeing as ours was shooting backwards, but after a lot of fine adjustments it started shooting forward as best to its ability as it could.

   As we were doing our refining there were many factors that we had to deal with. Some of the more obvious environmental factors were gravity and air resistance. Gravity had the pull on the ball bringing it as low to the ground as possible and air resistance we didn't deal much with in an inside setting. These 2 factors we couldn't control and had to hope instead that they worked in our favor.

 Next were the performance factors that we could control, such as friction, counterweight, angle of release and the durability of our paper model. Friction was something that we dealt with as I have said previous in the building of our model, any rubbing of any parts of the trebuchet would cause a big problem. Friction was also present in the pouch that we had to sew, the force needed to be there to ensure the ball to stay in the pouch, but it also had to be a smaller force in order for the ball to release at the proper time. The easiest factor we could control would've been the counterweight. We ended up using 45 washers in our bucket to achieve our maximum distance, but in order to hit the accuracy you needed to reduce the amount of weight. The most frustrating factor that I felt we had to accomplish was the angle of release, it was one of those things that once you perfected it, you didn't want to toy around. In the end the angle that worked best for us was a 45 degree release.

  In the end there were more performance factors vs. environmental factors so we had the opportunity to pretty much make it how we wanted, overlooking the gravitational force. We definitely got 80% of our frustration out on building this little guy, so the other 20% will be saved for the big one! Overall it was a smart idea building the paper model so we could get a better understanding of how exactly it works,

The picture shown below is not of our actual model, but yet a class members.

Competition Day

After we proceeded with our competition day we recorded the following data for our egg drop project:

Mass of Container: 130.6g
Container Dimensions ( l/w/h):20.5 * 21 * 11.5
Time of Fall: 1.12 seconds
Fall Distance: 5m
Condition of Egg:Perfect
Egg points Earned:153.1






The restriction that I felt was most limiting to us during our design was the fact that it had to have the dimensions or be less than 25*25*25. I felt this was the hardest for us because you could think of a lot of different designs when planning out the project but a lot of them were not capable of being used because they exceed the limits. It's obviously easily doable with what we were given but it would've been that much easier if there was no limits on dimensions.

The most effective part of our design was the pantyhose we used for suspension. We chose this part because it was different than all of the other designs and we knew it would be fairly stable since the pantyhose has lots of elasticity in them. Meaning it would be fairly lenient in the way our egg would be bounced around in the container. I felt that we really didn't have any non effective parts to our design because of all the tweaking we did before hand. If we were wanting to add another egg we would obviously have to get 2 more ponytails to double up the security. It would also be wise to add some cushioning and more layers of pantyhose to up the amount of suspension within the box.

Performance Day

Our group consisting of Greg, Shelby and myself came up with a design having the main focus being suspension. We took a circular box with the dimensions 20.5 by 21 by 11.5 cm and took 4 pieces of pantyhose that we stretched across our box and stapled to the sides. We made sure that we had one piece stretched on the top and 3 across the bottom to support our suspension system. It started off with bread in the bottom of our container along with packing peanuts with the container on, but we felt fairly safe in the sense that we didn't need it for support and it was instead reducing egg points from our total because of the mass. For this reason after test day we decided that we would go with a simplicity design, containing only the pantyhose and no lid.This meant that in order for our egg not to break we would have to make sure it was centered so that the box would land up right rather than on it's side or face. On the test day we dropped our container up t0 5 times, and then the day after 7 and not once did it break or crack so we felt confident enough to leave it alone and wait till test day!