Trajectory B/C

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Re: Trajectory B/C

Postby old » April 26th, 2010, 3:57 pm

swimmmm wrote:
zyzzyva98 wrote:It's good to have an equation on your graphs to get a good estimate for obscure amounts like that...

an equation?! wtf how do u do that??


We use the equation for a ballistic trajectory, including aerodynamic drag, then we use our empirical data as a correction factor. We have a doppler wind speed indicator that, unfortunately, only gives us the average wind speed and direction between the trajectory device and the target. We are able to plug all this into a laptop to get the aiming offset and correct range setting. Of course at Nationals we shouldn't really need the windspeed (unless it is set up like last year's, with the A/C vents cycling up at the extremely low ceiling). All in all we still only get about 1-2cm accuracy at the fartest distances when it is windy. You could do all this without the math but it would require a huge number of data points to account for all the possible ranges, heights, wind speeds and wind directions. On the other hand I spoke to people at last year's nationals who said that with the A/C cycling unpredicatably in the gym where trajectory was run their accuracy went from centimeters (what they were able to get with no wind) to tens of centimeters in the gym at Augusta. You just have to decide how competitive you want to be.

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Re: Trajectory B/C

Postby thepro » April 26th, 2010, 7:41 pm

I read the discussion about triggers that you guys have had before..but it didn't answer my question. My catapult's [picture attached] trigger is the white bar with holes every centimeter. When we pull a string attached to the bar, it releases the arm which shoots the golf ball.
The rules say that the device must fit within a 60X60 cube prior to all launches, but when we load the catapult to some of the lower holes the white "trigger arm" extends out of the box. Is this considered part of the device? or is it part of the trigger..and thus allowed to extend out of the 60X60 cube?
Image

(Sorry, reposting this..to clarify..b/c the image didn't work last time)

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Re: Trajectory B/C

Postby wlsguy » April 27th, 2010, 4:33 am

thepro wrote:I read the discussion about triggers that you guys have had before..but it didn't answer my question. My catapult's [picture attached] trigger is the white bar with holes every centimeter. When we pull a string attached to the bar, it releases the arm which shoots the golf ball.
The rules say that the device must fit within a 60X60 cube prior to all launches, but when we load the catapult to some of the lower holes the white "trigger arm" extends out of the box. Is this considered part of the device? or is it part of the trigger..and thus allowed to extend out of the 60X60 cube?

(Sorry, reposting this..to clarify..b/c the image didn't work last time)


My opinion;

The white bar will most likely be considered part of the device and will need to fit inthe 60x60 cube.
Some things that may change this (I mean may...)

1) if the bar is not permanently attached and is added seperately, it would be easier to argue that it is not part of the device.
2) making it a different color helps because you could say "everything white is part of our trigger".

If you can change it, I probably would.

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Re: Trajectory B/C

Postby haven chuck » April 27th, 2010, 5:10 pm

wlsguy, do you happen to know what the State tournament distance were for Ohio B this year, and perhaps the winning score?
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Re: Trajectory B/C

Postby wlsguy » April 27th, 2010, 7:32 pm

haven chuck wrote:wlsguy, do you happen to know what the State tournament distance were for Ohio B this year, and perhaps the winning score?


I think the B distances were 7.5m and 4m @50cm high.
I don't know the winning score but I do know that a 240 placed 7th.
(Our team had trouble with one of the distances. 4cm at the close target but 2ocm at the far one)

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Re: Trajectory B/C

Postby RndmPplPrsn » May 22nd, 2010, 9:34 pm

sj wrote:could you elaborate on how we could use kinematics because so far we have been testing extensively however it seems impractical to calibrate for all the points that are possible.


I had graphed 90 or so graphs using the averaged data for each peg and angle (Some were estimated by using kinematics because we had all of the variables needed that we chose. I also payed attention to the small stuff). We printed copies, and used that in our testing and competing.

My machine is built where most of the human factors have been removed or greatly minimized. In other words it is really consistent and predictable, all except for the bungees and their mounts.

There is a slight difference in force and speed when shooting a steeper shot than when shooting a shallower shot. This is because of gravity. However it didn't make much of a difference at State Competition :P.

Also I have found that there is no reason not to use an electromagnet for the trigger device. It is the best idea ever. I also made a change to my last design before state, but forgot to post pictures, they should be up soon.
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North Lake Regionals: 3rd: Trajectory, 4th: Picture This, 4th: History of Science

Hutto Invitationals: 2nd: Picture This, 4th: Forensics, 4th: Trajectory

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Re: Trajectory B/C

Postby AlphaTauri » May 23rd, 2010, 8:19 am

Does anyone know the winning score for Traj. at Nationals (B and C)?
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Re: Trajectory B/C

Postby Lily Essence » May 23rd, 2010, 3:05 pm

I'm sure both are in the negatives. I'm guessing somewhere around the -170s for first and -60s for medaling, but I didn't watch alot of devices compete, so that might not be accurate.
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Re: Trajectory B/C

Postby Phenylethylamine » May 23rd, 2010, 4:57 pm

AlphaTauri wrote:Does anyone know the winning score for Traj. at Nationals (B and C)?

Tech event raw scores don't seem to have been posted yet (and may never be, but there's some chance that we will get them eventually), but I know that Fayetteville-Manlius High School got first in Division C, and Fairfield Junior High got first in Division B. If nobody on this board knows, I might be able to contact someone from F-M and ask what their score was.
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Re: Trajectory B/C

Postby AlphaTauri » May 23rd, 2010, 6:09 pm

Lily Essence wrote:I'm sure both are in the negatives. I'm guessing somewhere around the -170s for first and -60s for medaling, but I didn't watch alot of devices compete, so that might not be accurate.
Really? I was thinking more along the lines of -400 for first (about 7 cm off each target, two bucket shots- one hit the bucket and bounced, the other went in, full graphs, and no penalties) and -200 to medal. Seems reasonable, but I have no idea.
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Re: Trajectory B/C

Postby RndmPplPrsn » May 23rd, 2010, 6:40 pm

To my surprise people seem to have lower standard machines and ability in Trajectory at the higher levels than I thought. The amount of machines at State that had scores in the thousands was pretty high.
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State: 1st: Trajectory, 6th: History of Science, 11th: Picture This

North Lake Regionals: 3rd: Trajectory, 4th: Picture This, 4th: History of Science

Hutto Invitationals: 2nd: Picture This, 4th: Forensics, 4th: Trajectory

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Re: Trajectory B/C

Postby hlall » May 23rd, 2010, 7:21 pm

We got 4th and were a few centimeters off each target. Only took two shots, since we didn't realize the time crunch at nationals.

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Re: Trajectory B/C

Postby ichaelm » May 23rd, 2010, 7:41 pm

I'm from BC in division B, we got 20th in trajectory. I was also surprised all the totally awesome devices there!! I think we got about 6 cm off on each target, and we hit the bucket twice. Actually, let me correct that: on our first bucket shot, it went inside the bucket, bounced up, and landed on the ground behind the bucket. However, through our goggles, my partner and I both thought it stayed in!!! :lol: :lol: And the whole crowd was cheering like mad!! So we didn't change the setting for the second shot. And that time we saw it bounce out. But we were convinced we had gotten -150 for the buckets. Until we talked to our friends sitting there, who showed me the truth (I even needed to see the video! :lol:) So with a score of approximately positive 20 by my estimation, we got 20th place. Again, all the devices were surprisingly accurate, and all of you guys handled yourselves really well. Does anyone else wanna share their performance?

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Re: Trajectory B/C

Postby starpug » May 23rd, 2010, 8:08 pm

I forgot to impound the pole that I use to set the trajectory position at nationals, but my partner was able to use his hand to do the same job. Time was a big issue, I had not time to check the power settings and little time to do more then guess at how much to readjust my device by after each shot. I was able to eak out a pretty decent score and come in 33rd though
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Re: Trajectory B/C

Postby Lily Essence » May 23rd, 2010, 8:33 pm

My coach told me after the coaches meeting that we weren't allowed to bring in lazers that said "Danger." He said only "Caution" was allowed, so we ripped the lazer off before impound. It didn't really matter because the bucket shot was 8 M out and 2 M to the right. We'd only callibrated to 8M, so even if we had the lazer, we didn't have the callibrations for something further than 8M in a straight line (I'm guessing the bucket would be something around 8200-8300 in a straight line).

My first shot at the close (6M, 1M high) was 200-something mm and the second 140-something.
My third (8M) was 60-something mm and the fourth 20-something.

16th place. Not perfect, but I'm pretty happy with it since I've had some really bad encounters with devices at state.

Did anyone else see the absolutely cute plastic cup and duct tape pulled back by a string in C division? It was so funny, but I felt bad for that team because FedEx lost their device...

AlphaTauri wrote:Really? I was thinking more along the lines of -400 for first (about 7 cm off each target, two bucket shots- one hit the bucket and bounced, the other went in, full graphs, and no penalties) and -200 to medal. Seems reasonable, but I have no idea.


Well, I'm not sure -400s are possible. Are you talking about C division? Because I was talking about B division...
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