Curious about the launching mechanism your team has decided on and why you may have chosen that method.
Thanks, everyone!
We’re trying the elastic tube (not so much for ease, but it’s fun trying to build a slingshot for a 10 inch boulder)
Problem is right now it launches like 10 feet! Anyone else getting better results?
Ours went about 50 feet… https://www.youtube.com/watch?v=QT2OmzrAhPI
Would recommend more strands of surgical tubing, do not stretch them beyond 200%, and replace them between events for consistency.
We decided to go for a compression spring linear accelerator, similar to a pin-ball machine.
Our concern with the surgical tubing to power the system was the degradation over time and variability due to ambient conditions. That being said, it does provide the ability to quickly change the power by adding or removing tubes to the system. With the rules about only launching from the courtyard, high-powered launching for full-court shooting wasn’t necessary.
We had considered going with the wheeled shooter (either single or double sided). This seemed like the best way to have variable launch speeds but decided against that due to our experience with the 2012 game piece and its manufacturing variation in both surface texture and compressability. I’m seeing more threads that suggest this may be an issue this year too.
1747 is using a double-sided, sequential wheeled shooter. The goal is to make the trajectory of the ball between the robot and the upper tower opening as close to linear as possible by maximizing ball velocity. With any luck we should get a test shot off with our competition shooter tonight.
I really hesitate to speculate what it will do, but the theoretical maximum ball velocity is about 88 mph and the shooter is ~1.8 horsepower worth of motor. Everyone on the team can’t help but grin or giggle when we talk about it, because it is absolutely silly and the very definition of overkill.
It’s going to be something…
There is no such thing as overkill 
Team 1708 is going with a sort of two wheel shooting approach but not on both sides. Hope to have a picture up tonight.
I’d like to see what happens. Good luck!
Have fun trying to launch such a large ball through such a small goal. Launching? No thanks.
Results at 100 responses:
Single-sided wheeled launcher 25 25.00%
Double-sided wheeled launcher 35 35.00%
Linear accelerator (pneumatic powered) 2 2.00%
Linear accelerator (elastic spring/surgical tubing) 4 4.00%
Rotating arm (catapult, trebuchet, etc.) 18 18.00%
Another method (please share in comments!) 4 4.00%
Launching? No thanks. 12 12.00%
Looks like we’re going to see a lot of wheeled launchers at the competitions this year.
What if we have more than one boulder scoring mechanism? 
The catapult/trebuchet design fits the theme better, so clearly it’s the best solution. If a team works out how to make a trebuchet launcher with a resetting sling I will be thoroughly impressed! It will be interesting to see how many catapult style launchers are pneumatic vs mechanical spring vs latex powered.
That’s what I thought for the first few days after kickoff. After we had a field mocked up and tested some prototypes, I changed my mind. It’s a tough target, but it’s doable.
Is more than one of them a launcher? If we need to score low, we plan on just reversing our intake, so we technically have multiple scoring mechanisms.
I think he may be referring to a modular shooter robot that can be a short robot that scores in the high goal or a tall robot that shoots in the high goal based on alliance partner’s robots. It was one of our ideas at one point early on in the season but ultimately gave it up.
Our prototype pneumatic catapult. We made 3/4 of our first shots. Quit while we were ahead and went to production.
Video is private.
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Slingshot? With this simple prototype design of two pieces of surgical tubing, we sent the ball slamming into the wall on the other side of the room:
http://put.nu/files/AFbPe9B.png
Surprisingly we tested a pneumatic powered linear punch that looks, but doesn’t work like 1114’s 2008 ball shooter. It’s actually more like 1102’s 2008 ball puncher. Made the shot we wanted every time the same way. Simple, easy and effective.
Based on our priority list/strategy, we don’t feel like we’ll need the ability to score in the high goal until later in the season. In order to ensure that we only go to competitions with polished, tuned systems, we’re building two seperate scoring mechanisms (one that only scores in the low goal, and one that scores in the low and high goal). Since we build a practice robot and have ample weight allowance/unbag time by going to four two day events, we’ll be able to iterate a ton on the high goal mechanism on our practice bot and be able to move it to the competition bot whenever it’s ready.
It’s also seems that both mechanisms could fit on the robot at the same time, which offers some interesting possibilites in terms of a modular robot.
Anyway, I answered the poll based on our late-season mechanism.