Trajectory B/C

[scifipi]

Thanks everybody! Well, I have a racquetball as a projectile. Its been working well as far as I know, but that isn't much... (it's my first year)
I don't think I wan't to switch to the plastic golf balls with the holes, because I'm afraid that the lightness will somehow affect the accuracy.

[zyzzyva980]

Right on, scifipi. Don't risk the plastic practice golf balls. All that really matters is what your machine can support. We use tennis balls because our machine was designed for it. If you have the right projectile, and it sounds like you do, then with enough practice you can get good enough to take a high placement.

[starpug]

Just as a note, Hacky Sacks are not permitted in this years rules. You can only use tennis balls, racquet balls, ping-pong balls, and plastic practice golf balls.

[RndmPplPrsn]

I've had experiance with Canon type devices for 2 years, the first year of the event in B and last year in C, I have discovered one major flaw in the design. The flaw is that canon type devices rely on pulling the projectile straight back, and as the rules require the devices to be smaller and smaller, the amount of power you can get from one of these devices drops. Because of this elastic with high and higher resistance is required in order to get the projectile to travel the required distance (I couldn't even achieve that with the strongest elastic I could find last year, but I had limited time so it's possible I could have gotten it to work eventually.) The greater forces generated by the stronger elastic can lead to other problems, for example last year I had the force of the launching device hitting the stopper rip the end cap of the launching device right off. In a catapult you are pulling the arm in an arc, meaning as the devices have to get smaller, the power is less greatly effected.

These are just my experiances, the design of your device maybe slightly different. My devices looked like this:
164|2/a2j_IMG_0021.jpg

976|2/a2j_img0154oqu.jpg

Well in this years 60 cm design my cannon was easily able to achieve 14-15m. Now with height at 10m, that might be hard to make, but so far distance/power has not been a problem. For me the pull designs have a flaw (Most of them) where when they sacrifice angle they sacrifice power, and vice versa. There are ways to design it without this happening, but they always seem much to complicated, as in unnecessary. Even most event proctors in my sate agree that Event B teams do better for the fact that they have simpler designs. My simplified design (6th Designed Version) was already difficult to create, we have tools (Personally), but my school hardly lacks the tools and funding to make those curved arcs on pull designs. I pride myself on how well I do compared to other larger, well funded schools, just saying.

I've also got a few questions. Does anyone have an idea for launching their device with a battery powered mechanism? If you haven't noticed yet, I use a cannon/Push device, I'm including the link to my Photobucket if you want to see more pictures. Another question I have is there a way to attach my "cannon" part of my device other than using a swivel latch, like in the design provided? So far I believe that is all, I've got the rest down.

For competition purposes I live in Texas if you don't feel like sharing ideas with a in-state competitor.

http://s290.photobucket.com/albums/ll26 ... 000116.jpg

http://s290.photobucket.com/albums/ll26 ... 000114.jpg

http://s290.photobucket.com/albums/ll26 ... 000110.jpg

[starpug]

I've had experiance with Canon type devices for 2 years, the first year of the event in B and last year in C, I have discovered one major flaw in the design. The flaw is that canon type devices rely on pulling the projectile straight back, and as the rules require the devices to be smaller and smaller, the amount of power you can get from one of these devices drops. Because of this elastic with high and higher resistance is required in order to get the projectile to travel the required distance (I couldn't even achieve that with the strongest elastic I could find last year, but I had limited time so it's possible I could have gotten it to work eventually.) The greater forces generated by the stronger elastic can lead to other problems, for example last year I had the force of the launching device hitting the stopper rip the end cap of the launching device right off. In a catapult you are pulling the arm in an arc, meaning as the devices have to get smaller, the power is less greatly effected.

These are just my experiances, the design of your device maybe slightly different. My devices looked like this:
164|2/a2j_IMG_0021.jpg

976|2/a2j_img0154oqu.jpg

Well in this years 60 cm design my cannon was easily able to achieve 14-15m. Now with height at 10m, that might be hard to make, but so far distance/power has not been a problem. For me the pull designs have a flaw (Most of them) where when they sacrifice angle they sacrifice power, and vice versa. There are ways to design it without this happening, but they always seem much to complicated, as in unnecessary. Even most event proctors in my sate agree that Event B teams do better for the fact that they have simpler designs. My simplified design (6th Designed Version) was already difficult to create, we have tools (Personally), but my school hardly lacks the tools and funding to make those curved arcs on pull designs. I pride myself on how well I do compared to other larger, well funded schools, just saying.

I've also got a few questions. Does anyone have an idea for launching their device with a battery powered mechanism? If you haven't noticed yet, I use a cannon/Push device, I'm including the link to my Photobucket if you want to see more pictures. Another question I have is there a way to attach my "cannon" part of my device other than using a swivel latch, like in the design provided? So far I believe that is all, I've got the rest down.

For competition purposes I live in Texas if you don't feel like sharing ideas with a in-state competitor.

http://s290.photobucket.com/albums/ll26 ... 000116.jpg

http://s290.photobucket.com/albums/ll26 ... 000114.jpg

http://s290.photobucket.com/albums/ll26 ... 000110.jpg

From looking at those pictures I believe I know the reason why your design doesn't have power problems like mine did.

You have a tube stretching the entire length and mine only covers half. I have a large tube which fits inside the other tube and pushes the ball out. So the distance traveled by the ball is limited.

In regards to your other question, what exactly do you mean by "canon" part? The thing which the ball comes out that goes up and down, or the thing that pushes the ball out?

[RndmPplPrsn]

If you look closely, in the back of my design there is a black "Swivel Latch." It is loose and shaky (Its own mechanism, not how I attached it), so in other words my "Cannon" (I call it the Launching Module) goes left to right easily. It was also very hard to construct for it to even be remotely close to straight.

If you don't know what I mean by "Swivel Latch," here is a picture, it's on the left side.

http://www.wildwesthardware.com/hinges/ ... _KIT_8.jpg

I also had a sort of epiphany while beginning on new designs after invitationals, I recognize in some manners in how the cannon is shot, leaves a lot of factors for the projectile to move horizontally, when not meant to. While the pull devices, if built decently enough, seem to always be relatively straight (Horizontal movement is less than 5cm). When building even the perfect push device, there is still a considerable horizontal movement. So for my pull design, is there a "best" way to assemble the elastic solid where I can easily, quickly, and repetitively (Without Tear & with Consistence) launch my device (Ex. Cotter Pin, Certain Latches)?

[scifipi]

Nice!

[inycepoo]

If you haven't noticed yet, I use a cannon/Push device, I'm including the link to my Photobucket if you want to see more pictures.

To what height can your cannon push device reach? I've always used a catapult-like design and last year at States they elevated the close target to 2.5 meters, and most of the push devices I saw couldn't make it to the top of the platform. The catapult's parabolic shaped arc lets you reach maximum height and distance, especially when placed at the right angle.

And my school isn't even close to being the most well-funded compared to the specialized schools we compete with in New York City (you know, the private ones with parents who live on Park Ave and such?), but my catapult design was easy and simple to make. All you need is a base attachment that stands still on the ground while the arm of the catapult rests at different pre-measured elevated angles. Then when you pull the arm down, height won't be a problem, and if your elastic is strong enough, distance is just as easy to get as well.

I made absolutely no changes this year besides replacing the elastic from last year's machine, as I got 4th at regionals (should've been 1st, my judges were from the major rival school & gave me an unfair penalty), and 4th at states again. With practice and a some luck I should be able to get 1st at regionals in two weeks :]

[haven chuck]

If you look closely, in the back of my design there is a black "Swivel Latch." It is loose and shaky (Its own mechanism, not how I attached it), so in other words my "Cannon" (I call it the Launching Module) goes left to right easily. It was also very hard to construct for it to even be remotely close to straight.....

I'm not sure if exactly get what you're saying, but have you tried using 2 hinges side-by-side. Also, the larger the hinges, the less they will "move" horizontaly.

[RndmPplPrsn]

Incycepoo: it can reach an angle of 88.6 degrees, and can still use all of the power, so I am pretty sure it can reach that height.

Look up LASA, we compete with teams like them, just not at regionals. For example my entire school often fits inside other schools cafeterias, and only offers 1-3 AP classes per grade. However we are awesome that is what allows us to do well. In other words public schools to us are rich (Facility wise, at least the ones near us)

Haven Chuck: What I mean is the actual mechanism is loose. So even if it drilled it in as hard as possible it still moves left and right when launching. We had to put spacers on the bar in order for it to have a straighter shot. I don't think having two of them will do anything, for the mechanism on which it pivots usually is pretty loose to begin with.