Air Trajectory B/C

[chalker]

I thought setting off a ball to hit the trigger was considered "gravitational potential energy", since it'll be going down an incline of some sort to actually hit the trigger?

The ball going down the incline would indeed be gravitational potential energy. The part you are missing is that you aren't CONVERTING that energy into air pressure or movement. Rather you are using that energy to trigger the release of energy contained within a spring. The key question to ask with any design is this: would the design work in a vacuum chamber? If your answer is YES, then it most likely is NOT compliant with the rules regarding air pressure / movement.

[sciolylover13]

And a related question: what do you do when you can't find a ball that fits your pipe perfectly (but of course your pipe is larger than your ball)? Last season we used tape, but noticed over time it lost consistently. Started with great consistency, but over time it would somehow act weirdly (making the projectile fit very, very tightly) so not so great consistency in the long run, at least from our experience.

What ball are you using? I use plastic ping pong balls that fit a 1 1/4* in. PVC pipe perfectly.

*I bought said PVC pipe last year, so I don't remember the exact diameter of it. I'm pretty sure it was 1 1/4 though.

Even better, is a practice golf ball, which is very similar to a ping pong ball, but since it has dimples, it has less of a tendency to drift away from the desired trajectory.

Huh, really? Might have to look into that.

[Fanglin]

What ball are you using? I use plastic ping pong balls that fit a 1 1/4* in. PVC pipe perfectly.

*I bought said PVC pipe last year, so I don't remember the exact diameter of it. I'm pretty sure it was 1 1/4 though.

Even better, is a practice golf ball, which is very similar to a ping pong ball, but since it has dimples, it has less of a tendency to drift away from the desired trajectory.

Huh, really? Might have to look into that.

It worked better than the ping pong ball, and it is about the same size as one, so it could probably fit into the same pipe that you were using the ping pong ball. Also, the barrel that I used was not made out of PVC or any other pipe. Instead, I used a fluorescent light cover which happened to be just the right size! This is better, because then it is easier to cut, and create variables with.

[Bazinga+]

Even better, is a practice golf ball, which is very similar to a ping pong ball, but since it has dimples, it has less of a tendency to drift away from the desired trajectory.

Huh, really? Might have to look into that.

It worked better than the ping pong ball, and it is about the same size as one, so it could probably fit into the same pipe that you were using the ping pong ball. Also, the barrel that I used was not made out of PVC or any other pipe. Instead, I used a fluorescent light cover which happened to be just the right size! This is better, because then it is easier to cut, and create variables with.

I was originally using a foot pump which was connected to a tube to shoot ping pong balls, but I realized ping pong balls weren't very consistent because they curve very easily along with other problems. I switched to foam practice golf balls but I couldn't reach the far distances so I had to replace my pump with a ball to get it to go farther. With these balls I got insane consistency (15 cm off both far and close target and got both bucket shots at regionals)

[windu34]

Huh, really? Might have to look into that.

It worked better than the ping pong ball, and it is about the same size as one, so it could probably fit into the same pipe that you were using the ping pong ball. Also, the barrel that I used was not made out of PVC or any other pipe. Instead, I used a fluorescent light cover which happened to be just the right size! This is better, because then it is easier to cut, and create variables with.

I was originally using a foot pump which was connected to a tube to shoot ping pong balls, but I realized ping pong balls weren't very consistent because they curve very easily along with other problems. I switched to foam practice golf balls but I couldn't reach the far distances so I had to replace my pump with a ball to get it to go farther. With these balls I got insane consistency (15 cm off both far and close target and got both bucket shots at regionals)

Id be careful with the word "insane consistency". To some teams, 150 millimeters (which translates to subtracting 150 points from score) is fabulous, but to others, it isn't good enough. When you say both bucket shots, are you just hitting the outside of the bucket or touching the bottom as well?

[Bazinga+]

It worked better than the ping pong ball, and it is about the same size as one, so it could probably fit into the same pipe that you were using the ping pong ball. Also, the barrel that I used was not made out of PVC or any other pipe. Instead, I used a fluorescent light cover which happened to be just the right size! This is better, because then it is easier to cut, and create variables with.

I was originally using a foot pump which was connected to a tube to shoot ping pong balls, but I realized ping pong balls weren't very consistent because they curve very easily along with other problems. I switched to foam practice golf balls but I couldn't reach the far distances so I had to replace my pump with a ball to get it to go farther. With these balls I got insane consistency (15 cm off both far and close target and got both bucket shots at regionals)

Id be careful with the word "insane consistency". To some teams, 150 millimeters (which translates to subtracting 150 points from score) is fabulous, but to others, it isn't good enough. When you say both bucket shots, are you just hitting the outside of the bucket or touching the bottom as well?

When I say 15 cm off that doesn't mean I have 15 cm consistency. If i did the same shot again it will land in almost exactly the same spot. I didnt have the chance to Calibrate as much as I wanted to. As for the bucket, it landed inside the bucket both times which was placed at about 7.5 meters and 1.5 meters to the left. It was a 1 gallon bucket.

[HandsFreeCookieDunk]

Hey guys,

My team was looking into using the base from a stomp rocket to convert the energy of the falling mass into air pressure and I wanted to get someone else's opinion on its legality. I've noticed that some other events has rules that specifically disallow manufactured parts, and I didn't see such a rule for this event. Did I miss a rule, is there some sort of "Spirit of the problem" rule that this breaks, or is it completely legal?

[windu34]

Hey guys,

My team was looking into using the base from a stomp rocket to convert the energy of the falling mass into air pressure and I wanted to get someone else's opinion on its legality. I've noticed that some other events has rules that specifically disallow manufactured parts, and I didn't see such a rule for this event. Did I miss a rule, is there some sort of "Spirit of the problem" rule that this breaks, or is it completely legal?

Sounds perfectly legal to me.

[chalker]

Hey guys,

My team was looking into using the base from a stomp rocket to convert the energy of the falling mass into air pressure and I wanted to get someone else's opinion on its legality. I've noticed that some other events has rules that specifically disallow manufactured parts, and I didn't see such a rule for this event. Did I miss a rule, is there some sort of "Spirit of the problem" rule that this breaks, or is it completely legal?

What you describe is a very common design used by teams.

[kaziscioly]

What are the best methods for initial calibration of your device? struggling w/ inconsistency in trying to set up initial dropping points for the mass