Air Trajectory B/C

[bernard]

In our state competition, there are simply wide range of students/coaches/parents that compete and it is not uncommon that many of them do not carefully follow the websites or forums such as this. I am not a coach of this event so I was not fully aware of the details, I just started helping out a few weeks ago and when I read the rule, it did not even occur to me that different type of practice golf balls would be illegal. I don't have any problem with the intent of the ruling but I wish if there was this rationale from the beginning, why not just spell it out? Foam balls are illegal, don't even think of trying to use it?

I think somewhere in the rules manual there is a short blurb that mentions rules clarifications and FAQs on the official website. A lot of teams that scan the rules don't scan this so you might have to look at a booklet version of the rules (the one you'd find in the official Science Olympiad store or mailed to your team by your state supervisor). In regards to the forums, nothing on here is official, it's just an open place for people to share ideas or interpretations of the rules. Participating in or simply reading the forums can be extremely helpful, but event supervisors aren't expected to do anything in accord to what is mentioned on the forums, since its not official.

[bernard]

Ok, so I'm competing in this event and I have a couple of weeks to pull together something good. So far, I really haven't had the best time and I'm pretty stumped. This event is pretty new for me and out of my comfort zone - I'm more of a balsa builder or a good studier. As a result, I've used up pretty much all of my creativity. What's an idea I can base my design off of that will be consistent and able to fire up to 8 meters? Any general tips? Thank you to anyone who replies!

A stomp rocket or something made out of a 2-Liter bottle is something I've seen a lot at competitions probably because its simple to do. However, I prefer using a bike pump because it falls consistently. I'll give you a brief overview of the materials I'm using. For my barrel, I'm using 1.5-inch PVC, cut to about a foot in length. At the end I have an cap with a brass barb adapter on it (I drilled holes and fit it on). Put some tape where your ball goes so it fits tightly. Pretty simple. The bike pump has a mass attached to it (you need to separate the handle and mass for impound). Pretty simple, but that's good since there's not too many factors or places to mess up. You'll want to make a reliable way of angling your barrel. The Image Gallery for Trajectory (an older, slightly different event) has some good images of what people have done in the past.

Hope this helps, and if anything is unclear or doesn't work, let me know and I'd be happy to help.

Thanks for your help! As of now, I've been using a barrel very similar to yours - a 1.5 inch PVC pipe about 10 inches long that can be angled easily. However, I tried using a bike pump when I first started working on the event, but none of my pumps could produce enough pressure to even move a ping pong ball. Could I ask what type of pump you're using? Also, I'm having some trouble visualizing how you would connect the bike pump to the barrel - could you maybe post a picture of how it looks? (If you don't want to reveal your design to me, I'm perfectly fine with that.) Thanks again for the helpful response!

I'm happy to share anything you want to know about my device, but I'm also a bit lazy and don't want to get up to take a picture right now. I think describing will work well here. As I said earlier, I had a end cap (the round ones that go around the pipe, not the ones that are plugs) and I drilled a small pilot hole just to make sure everything would eventually be centered (it doesn't matter, I'm just really picky). I moved up drill bit sizes and kept drilling, and the largest one I had was a bit smaller than the size of the threads on my [/url=http://www.steam-brite.com/images/barb_ ... itting.jpg]threaded bard brass fitting[/url]. I actually had to angle the drill bit just to get a hole that would be larger, but not too large because then it would leak. I attached the barb end of the brass fitting into my drill and used that as a bit and screwed it into the hole I had made. If done well, it makes a tight fit, just don't drill your initial hole larger than the threads.

The bike pump I'm using is an ordinary standing bike pump (not a compact pump that you might find in an emergency kit) and it's about 50cm tall. If your ball isn't launching, try putting your palm over the end of the barrel and feel for leaks. If its leaking, then add some masking or painters tape in the area where it is leaking (just a short strip at a time). Keep doing this and feeling for leaks until it starts launching. If it launches but doesn't go the full 8m, add more tape to make the ball fit tighter while still feeling for leaks. For our device, I added just the right amount of tape so right when the pump handle is about to fall all the way, the ball launches.

Also, ping-pong balls you use will vary slightly in diameter and might not all fit the same in your barrel. Try to load your ball the same way every time (same orientation, pushed into the barrel the same distance) and label your balls so you know you're using the same one every time (if you have multiple). We did half of our calibration with one ping-pong ball and someone stepped on it since we were in the hallway so we had to redo all our calibrations for another ping-pong ball.

Hope this makes things more clear. If theres anything I can go more in depth about, let me know and I'd be happy to.

[chalker]

....
I think somewhere in the rules manual there is a short blurb that mentions rules clarifications and FAQs on the official website. .....

It's actually quite prominent:

In the printed manuals, at the TOP OF EVERY PAGE, in bold text it says "Read the General Rules in the manual and on www.soinc.org as they apply to every event." The same happens in the mobile app manuals, but appears at the BOTTOM OF EVERY PAGE.

The back inside cover of the manual has the general rules, as does this webpage: http://soinc.org/ethics_rules Rule #3 states: "Students, coaches and other adults are responsible for ensuring that any applicable school or Science Olympiad policy, law or regulation is not broken. All Science Olympiad content (e.g., policies, requirements, clarifications, FAQs, etc. on soinc.org) must be treated as if it were included in the printed rules."

[peteb]

It's actually quite prominent: In the printed manuals, at the TOP OF EVERY PAGE, in bold text it says "Read the General Rules in the manual and on www.soinc.org as they apply to every event." The same happens in the mobile app manuals, but appears at the BOTTOM OF EVERY PAGE.

I just want to express appreciation for the whole "tone" of this discussion, (very cordial and patient) and the "spirit" of investigation in the Science Olympiad approach. What I value for my students is that not everything is black and white, spelled out and obvious. The first time we participated, we had some crushing blows, (tears!) because we did not read the rules carefully enough, just assumed this or that was OK. Seems to me that one of the fantastic benefits of this competition is that those who approach it with a drive to do the best, and keep in the spirit of the competition do well, or at least learn a lot. I've met many individuals and teams who assume they have a right to win, etc. and are disappointed. None of us can assume to win. It is earned by determined students with the help of their coaches.
Thank you to all who keep it going. I enjoy the challenge of trying to get it right!

[hogger]

And yet many competitions and regionals are allowing foam balls, why? Because even in the clarifications, it is not entirely clear it is not allowed. The requirement that the word has to be on the package is ambiguous while the other item in the clarification seems to say that it might be allowed. I am not trying to be difficult here and I know a lot of work and time are put into this. But if you don't want us to use foam balls why not say so? It seems like it is a very roundabout way of saying foam balls are not allowed. After all, foam is really a kind of plastic.

Is it fair that in some other regionals or competitions are allowing this and the people who happened to carefully read this forum might be at a disadvantage against people who might not be as conscientious?

Yes I know, this is all unofficial discussion unrelated to the actual SO governing body.

Just IMO. Cheers

[bernard]

And yet many competitions and regionals are allowing foam balls, why? Because even in the clarifications, it is not entirely clear it is not allowed. The requirement that the word has to be on the package is ambiguous while the other item in the clarification seems to say that it might be allowed. I am not trying to be difficult here and I know a lot of work and time are put into this. But if you don't want us to use foam balls why not say so? It seems like it is a very roundabout way of saying foam balls are not allowed. After all, foam is really a kind of plastic.

Is it fair that in some other regionals or competitions are allowing this and the people who happened to carefully read this forum might be at a disadvantage against people who might not be as conscientious?

Just IMO. Cheers

To me it seems very clear. You can use HDPE golf balls, but the words "plastic," "practice," and "golf ball" just appear somewhere on the original packaging. If you want to use HDPE golf balls, make sure it has those words and you should be fine.

[hogger]

That is not very clear to me. The same material if put in a package that has the word plastic in it is legal and not if it does not. It is border on relying on some marketing department or who design the package for the material to be legal and not at all scientific, seems to me. Wouldn't no foam balls be so much clearer? Why are some regionals allowing foam balls?

[bernard]

That is not very clear to me. The same material if put in a package that has the word plastic in it is legal and not if it does not. It is border on relying on some marketing department or who design the package for the material to be legal and not at all scientific, seems to me. Wouldn't no foam balls be so much clearer? Why are some regionals allowing foam balls?

The foam balls would be allowed if they came in a package that had the words "plastic practice golf ball." There will be some variation in what is allowed between event supervisors, but the FAQ makes it clear that those are the words that need to be on the packaging. The rules had the wording "plastic practice golf ball" and the FAQ is staying consistent with it.

[cco11029]

Ok, so this is my first year competing in air trajectory, and a couple of the rules were rather unclear. My main question is on the process of choosing distance during the event. Are you expected to estimate the distance of the platform, or do they actually announce it beforehand? Basically, I want to know wether or not we should record the distances exactly during testing periods. If it is left to estimation exact measurements will not be necessary. If it is announced, we need to get those recorded sooner than later. Any responses would be greatly appreciated.

[bernard]

Ok, so this is my first year competing in air trajectory, and a couple of the rules were rather unclear. My main question is on the process of choosing distance during the event. Are you expected to estimate the distance of the platform, or do they actually announce it beforehand? Basically, I want to know wether or not we should record the distances exactly during testing periods. If it is left to estimation exact measurements will not be necessary. If it is announced, we need to get those recorded sooner than later. Any responses would be greatly appreciated.

After impound, the distance of the two targets and the location of the bucket are announced. You should record distances exactly during testing period and know how to adjust your device for targets of different distances, but due to factors that might affect your performance in a different location, you should be able to adjust your device finely.