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Air Trajectory B/C

Posted: August 22nd, 2015, 2:36 pm
by robotman
Discussion for Air Trajectory B/C.

Resources:
Air Trajectory Wiki
2015 Thread
Air Trajectory Image Gallery

Re: Air Trajectory B/C

Posted: September 2nd, 2015, 7:34 am
by Argus
Anyone have any clue what is new for this year?

Re: Air Trajectory B/C

Posted: September 2nd, 2015, 4:33 pm
by chalker
Anyone have any clue what is new for this year?

Yes;) Might as well give a high level summary of major changes since this is in my committee. As always though, you really need to read the actual rules to understand the specifics:

-Nominal mass items like strings / container walls aren't considered part of the falling mass
-Max device size reduced: 70cm cube C, 80cm cube B
-Foam golf balls allowed
-Launch area size reduced: 1m square
-Far target can be up to 2m right or left of the centerline
-Bucket shot max points increased to 300

Re: Air Trajectory B/C

Posted: September 2nd, 2015, 4:36 pm
by sciolylover13
Anyone have any clue what is new for this year?

Yes;) Might as well give a high level summary of major changes since this is in my committee. As always though, you really need to read the actual rules to understand the specifics:

-Nominal mass items like strings / container walls aren't considered part of the falling mass
-Max device size reduced: 70cm cube C, 80cm cube B
-Foam golf balls allowed
-Launch area size reduced: 1m square
-Far target can be up to 2m right or left of the centerline
-Bucket shot max points increased to 300
Guess that means I have to start working on my bucket shot aiming skills!!
Oh and my angles.
Yay! Time to start working on my device and do countless hours of repetitive monotonous practice to get the ball in one spot!!

Re: Air Trajectory B/C

Posted: September 2nd, 2015, 4:51 pm
by Argus
Anyone have any clue what is new for this year?

Yes;) Might as well give a high level summary of major changes since this is in my committee. As always though, you really need to read the actual rules to understand the specifics:

-Nominal mass items like strings / container walls aren't considered part of the falling mass
-Max device size reduced: 70cm cube C, 80cm cube B
-Foam golf balls allowed
-Launch area size reduced: 1m square
-Far target can be up to 2m right or left of the centerline
-Bucket shot max points increased to 300
My rule manual is coming in tommorow haha. I just am super impatient and excited to start. The 70cm cube size restrictions will probably be the most difficult part but it can definitely be done. Thank you very much for the info I can't wait to start building!!!!!

Re: Air Trajectory B/C

Posted: September 2nd, 2015, 7:42 pm
by windu34
Any plans on how to adapt to the size restrictions? Also what kind of pvc do you use? Thin walled?

Re: Air Trajectory B/C

Posted: September 12th, 2015, 7:33 pm
by windu34
Do you guys use physics to calculate exactly how far and what force is needed to launch the projectile or do you just test it?

Re: Air Trajectory B/C

Posted: September 13th, 2015, 7:02 pm
by daycd
Just test. The important thing is that your machine is consistent.

Re: Air Trajectory B/C

Posted: September 13th, 2015, 7:22 pm
by bernard
Just test. The important thing is that your machine is consistent.
Exactly the approach we use for this event and many other builds. If you're starting out and aren't sure if something will work, just test the main step(s) that might not work. If you're dropping a mass onto a bottle, you probably don't need to make a contraption that drops the mass yet. And if something just barely works, there's a chance it won't work under slightly different conditions.

Re: Air Trajectory B/C

Posted: September 13th, 2015, 7:32 pm
by windu34
Actually this will be my second year with this event and I have a lot of experience. Last year, I only tested to achieve my results and placed second at state, but this year, I am in physics and have started wondering if there would be a way to actually calculate the initial velocity that I would need for each launch and then quantify the force produced by my device into an initial velocity that I could use as a variable.
I think there is a ratio that relates the effect of air resistance to distance that I could find and employ
Thoughts?

Re: Air Trajectory B/C

Posted: September 14th, 2015, 4:57 am
by laidlawe18
I think that in theory, that would be ideal, but in all practicality, it's probably not going to work. My goal for this year is to make something that is super consistent, and can accurately be modeled by some kind of function. Rather than using physics to find a function, I think you'd just be better off just testing it a bunch and then making a regression equation. With the far target no longer on the center line, there are way to many individual places that the target could be to test and perfect all of them.

Re: Air Trajectory B/C

Posted: September 14th, 2015, 6:14 am
by windu34
I think that in theory, that would be ideal, but in all practicality, it's probably not going to work. My goal for this year is to make something that is super consistent, and can accurately be modeled by some kind of function. Rather than using physics to find a function, I think you'd just be better off just testing it a bunch and then making a regression equation. With the far target no longer on the center line, there are way to many individual places that the target could be to test and perfect all of them.
For the far target, couldn't you just bring a laser pointer to aim your device and then use Pythagorean theorem to find the distance?

Re: Air Trajectory B/C

Posted: September 14th, 2015, 11:00 am
by laidlawe18
I think that in theory, that would be ideal, but in all practicality, it's probably not going to work. My goal for this year is to make something that is super consistent, and can accurately be modeled by some kind of function. Rather than using physics to find a function, I think you'd just be better off just testing it a bunch and then making a regression equation. With the far target no longer on the center line, there are way to many individual places that the target could be to test and perfect all of them.
For the far target, couldn't you just bring a laser pointer to aim your device and then use Pythagorean theorem to find the distance?
Yes, but the problem is that you're going to get numbers like 6.243237 or something. It is impractical to test every single possible distance, because there will be so many this year. Having some kind of function for weight or height dropped from in relation to distance would be much more practical.

Re: Air Trajectory B/C

Posted: September 15th, 2015, 7:45 am
by SPP SciO
I didn't see anything in the rules prohibiting laser alignment (unlike scrambler, for instance), so I imagine it'll be a simple Pythagorean calculation, and I imagine the hope is that the graphs will actually be useful!

Speaking of graphs, rule 6.c.v seems a little weird - only one graph gets scored, but that score gets multiplied by 4? What if a team makes 3 great graphs but a mistake on the 4th one which is scored? Or vice versa? If it's just a time issue to get all graphs scored, why not require just one? Or let the students decide which of the 4 to score, not "selected by the event supervisor."

Re: Air Trajectory B/C

Posted: September 15th, 2015, 8:29 am
by windu34
I didn't see anything in the rules prohibiting laser alignment (unlike scrambler, for instance), so I imagine it'll be a simple Pythagorean calculation, and I imagine the hope is that the graphs will actually be useful!

Speaking of graphs, rule 6.c.v seems a little weird - only one graph gets scored, but that score gets multiplied by 4? What if a team makes 3 great graphs but a mistake on the 4th one which is scored? Or vice versa? If it's just a time issue to get all graphs scored, why not require just one? Or let the students decide which of the 4 to score, not "selected by the event supervisor."
Usually all graphs are done in the same format by the team so if one graph has a mistake, they all will have the same mistake. The point of the graphs is that students are SUPPOSED to be graphing velocity by time, acceleration by time, etc. We are SUPPOSED to be using physics to calculate how to calibrate our device (of course most students don't)

As for the laser, my team has a distance laser that is accurate to the mm so I might just use that instead of relying on the ES to be precise on target placement (which most probably wont be able to)