what was the best shooting mechanism for 2016?
 

During the build season we had a discussion about our way to shoot the boulders into the high goal. The main two mechanisms were(of course) a catapult and a wheeled shooter. Throughout the season I've seen some amazing teams that used both methods and reached an amazing consistency, but somehow I always thought that the catapult is much more consistent because it didn't had nothing to do with the condition of the boulder.
I was wondering if someone on CD have some data about the type of shooting mechanism that teams that were on Einstein had?
I would be happy to hear what other people think? was the catapult more effective or was it the wheeled shooter?

Re: what was the best shooting mechanism for 2016?
 

The best shooting mechanism was the optimized one. Whether it had wheels, or a catapult wasn't the point.

I have seen extremely successful wheeled shooters and catapults as well as extremely unsuccessful wheeled and catapults.

Its all in the execution.

Re: what was the best shooting mechanism for 2016?
 

This is just guessing, but the catapult could probably be unreliable sometimes if the springs got stretched out. The wheeled shooter is effective, but as you said it has much to do with the condition of the boulder. Also if the wheels don't spin fast enough (be a programming or mechanical issue) it won't shoot out as expected. "Its is all in the execution"

Re: what was the best shooting mechanism for 2016?
 

I still say the linear puncher is the best mechanism (if done well). However, hooded flywheel shooters seemed to be the most successful.

Re: what was the best shooting mechanism for 2016?
 

Both wheeled shooters and catapults were equal I feel, but the best wheeled shooter was the turret-style from 254, 179, and 5172. The best catapult was between 148 and 118. (Texans know catapults, I guess) The best "Other" shooter was from 3360 and their "mini catapult" inside their arm.

Re: what was the best shooting mechanism for 2016?
 

You have to include 1501 and their turret I think. They been really successful with it. I dont really know what mechanism did 330 used but they also had a solid shooter that scored well, probably gets them to the category of the best "Other" shooters.

Re: what was the best shooting mechanism for 2016?
 

When it comes to "other" shooters, I'd throw 1519 into the mix for one of the best linear punchers.

Re: what was the best shooting mechanism for 2016?
 

330 had a good linear punch mechanism (A piston hit the ball), but I feel it had to be a bit to close to the goal. I think that 3360 had a shooter that could shoot from farther away, and the batter, which made them more flexible. As for 1501, they had a great turret shooter, but my list wasn't definitive, it was just some robots with good turrets.

Re: what was the best shooting mechanism for 2016?
 

Now the real lesson is to see that this applies to nearly every year. Great execution can make a wide variety of concepts work at the highest levels. The "right" mechanism depends on a variety of factors - you have to weigh what your team has experience with, what your team can prototype the best, what your team can optimize most easily, what has the right tradeoff between performance ceiling and simplicity, etc.

I think my team should have done a catapult, and that more teams should have done catapults than wheeled shooters. It seems like double wheeled shooters were the easiest to get range and repeatability out of, and they did not suffer as many problems with the goal chains as backspin (one wheel) shooters seemed to, but both could be optimized.

Re: what was the best shooting mechanism for 2016?
 

Although there were many different successful shooter designs this year, I think the best ROI was in the hooded flywheel shooter, which was why it was so prevalent. Here's why:

1) Hooded flywheel shooters are space efficient over other wheeled shooters because they use less wheels, and if you design for it, the hood can pop down under the low bar (saw a few teams do this).

2) Hooded flywheel shooters are relatively easy to test/tune. Most catapult designs require mechanical tweaks to adjust power and speed. As long as your shooter wheels are overpowered, you can tune them down with encoders until you get the desired effect.

3) Hooded flywheel shooters put a backspin on your ball. Due to aerodynamics that I don't exactly understand, this means that the ball goes further, but it also means that if you hit the top of the goal, the ball has a high probability of rolling in. (hitting the top of the goal is far more common than the bottom because the robots are shooting up at the goal from below.

4) Hooded flywheel shooters are relatively easy to design. The only moving components are a single axle with wheels on it. No potential energy storing devices are necessary. Most teams have also tried this kind of shooter at some point in their history.

5) While both catapults and wheeled shooters can get worn down. Wheel wear is clearly visible, while springs or surgical tubing getting stretched is not as easy to spot.

I'm not saying necessarily that hooded flywheel shooter is objectively the best (because each design has its own merits). I am saying that the hooded flywheel shooter gives the best ratio of time spent (designing, building, tuning) to effectiveness.

Re: what was the best shooting mechanism for 2016?
 

All other things equal (specifically, tip speed / torque of the flywheel, and energy transfer between the wheel and the ball), a hooded shooter will throw a ball half as fast as a double wheel shooter.

For my team this was the biggest challenge with our shooter - actually getting it to shoot far enough to make a shot from the outer works was difficult with just one mini-CIM on the shooter. We probably could have done it with two, but then packaging became an issue.

Re: what was the best shooting mechanism for 2016?
 

And this is why 775Pros are a godsend.

Crazy power output? check

Fast as heck so I don't have to gear up? check

I would also argue that the main reason that the two wheeled shooter is faster is because it has twice as many motors. If you really need the extra power Vex has you covered

Re: what was the best shooting mechanism for 2016?
 

I just realized the entire Carson division winning alliance had catapults.. Go catapults! :D

Anyway, I agree with most of the posts on this thread. It depends on the execution and implementation behind it. Whichever method of shooting you go with, find a way to implement it well and make it flexible. (for example, the ability to shoot from multiple positions from the field, outerworks, batter, etc.)

Re: what was the best shooting mechanism for 2016?
 

It's not an argument or random postulation, it's physics. It's the difference between a ball being "rolled" or "tossed" out of a shooter. Let's make some assumptions - zero slip between the wheel and the ball, zero slip between the ball and the hood of the shooter, perfect energy transfer, wheels don't even slow down, whatever.

A two wheeled shooter contacts both sides of the ball at a certain tip speed, V. Both edges of the ball are being moved at the same speed, so the ball does not rotate at all, it is fired straight out of the shooter. The center of the ball therefore also moves at V.

Now consider a hooded shooter. The flywheel rolls one edge of the ball forward at V, and the other side of the ball is rolling along the flywheel. Instantaneously, the tip velocity of the other side of the rolling ball is zero (or is it the other way around...) - so the velocity of the center of the ball is V/2. When the ball exits the shooter (is released from the constraints placed on each end of the ball) it'll travel at the speed the center of the ball is moving.

Real world factors will make your result vary, but in general, all other things equal, hooded shooters do move balls half as fast (and half as far) as two wheeled shooters. This is not due to having fewer motors - tons of teams put more than one motor on a ball. This is just due to the dynamics of a ball rolling through a shooter.

A 775pro's power is greater than a mini-CIM, yes, but there are also good reasons not to spin your flywheel at 19,000 RPM, and tip speed is far from the only factor that determines how far your ball will fly. You probably end up gearing the 775 down to a speed closer to the mini-CIM, but with more power, which would probably reach a greater distance yeah. Too bad you can't buy those right now...

Re: what was the best shooting mechanism for 2016?
 

For a non-turret style shooter which was beautiful optimized - see 971. I'd definitely say they were one of the best shooters at worlds, coupled with a beautiful two ball auto. Also, 1678.

Between 148 and 118, I'd have to say 148 - they scored 12 balls in one match (with 1678 putting up ten more) for the "most balls scored" in the 270 point match during Hoppers divisional eliminations. But kudos to both Texas teams for showing us how catapults should be done.

Re: what was the best shooting mechanism for 2016?
 

Definitely agree with this. It is all in the optimization and execution...

Team 230 built a catapult... and we had the 2nd highest OPR at the Championship event. Our catapult was highly optimized (as noted in this post: http://www.chiefdelphi.com/forums/sh...9&postcount=47) ... and it did not suffer from any kind of reliability issues to to springs stretching out, because there were no springs. It is a fully electric catapult, driven by 2 mini-CIMs. The best part about the catapult was that the boulders that were being damaged by the wheeled shooters were not an issue for us as the catapult is unaffected by the size and shape variations.

Re: what was the best shooting mechanism for 2016?
 

I feel that "best" is relative to what you value the most. For our team accuracy is the most important over distance, and speed. If you are going to take a shot make it count otherwise you spend more time chasing it down.

We did a two wheeled shooter in 2012 and actually found it to be much less accurate than the single wheel shooters. We thought that going with high speed motors on both sides of the ball would give us more range and having two wheels would make it more consistent but we were wrong. What we ultimately found out was that there is better energy transfer between the wheel and the ball when you give it a curved track to allow the mass to get up the wheel's spinning velocity. Because of this it was more consistent and seemed to go further even with less powerful motors. Ours just kinda burned out on the ball because we were taking something that is not moving at all and all of a sudden trying to get it up to full speed. This varied based on how well the wheels gripped the ball which changed as the wheels got dirty or the balls varied.

Echoing the previous comments I think execution is key and that any design can be successful as long as the time is put in to remove inefficiencies and variability.

Re: what was the best shooting mechanism for 2016?
 

Regardless of type of shooter, there were patterns of thought process that lead teams to consistent, optimized shooting mechanisms.

Every consistent shooter had an optimized shot trajectory. There were two different camps here. One camp set the peak of their shot's parabola at the top of the goal, taking advantage of the vertical goal to maximize the sweet spot of their shot. In fact, many teams had a single, workable shot from the outworks all the way to right in front of the batter. The other camp, including teams like 971 and 987, were able to adjust their shot angle using vision targeting. This camp then used flat shot trajectories, decreasing the impact of exit velocity consistency on shot accuracy.

Additionally, many teams in both camps maximized their release height in order to circumvent the threat of blockers and further maximize their trajectory's sweet spot.

The next variable that posed a threat to consistency was ball variation. As balls were used on the field they became more compressible. Catapults elegantly avoided this variable by never compressing the ball. For the flywheel shooters, minimizing compression also decreased energy transferred to the ball. Thus, competitive flywheel shooters counteracted this with higher wheel surface velocities, more power, and larger contact patches on their wheels. Flywheel shooters also relied on sensor feedback in order to accurately control their wheel velocity. While my team did not extensively prototype the two wheel shooter design, I would also conjecture that the single wheel designs were more consistent because they had less variables to control.

Catapults on the other hand still had a slew of problems to contend with in order to get consistent exit velocities. Pneumatic catapults had to deal with airflow, limited by their solenoids, regulators, pneumatic tubing, and fittings. From talking with some pneumatic catapult teams, I heard that many used high-flow solenoids in conjunction with air tanks after the regulator. Spring powered catapults had to deal with spring wear and consistent release/pull-back points. My team ended up finding success with high-quality extension springs.

Lastly, alignment time was critical in this game, given that teams could only hold one ball. Both camera and flashlight alignment was proliferate, and some teams used turrets to great success, which could align fast and accurately.

Re: what was the best shooting mechanism for 2016?
 

I liked 125's catapult. It was integrated into their utility arm, so it was able to shoot from very high up. That paired with its ability to shoot from anywhere on the field made it very difficult to defend against.

Re: what was the best shooting mechanism for 2016?
 

Also 148, the robot with the highest opr at champs, had the highest opr. Catapults are good.

Re: what was the best shooting mechanism for 2016?
 

Those are two examples. They certainly don't constitute a proof, especially if you're basing it solely on OPR.

Why don't we do something similar and look at all the captain and first selections that made Einstein- not necessarily representative of the best, but pretty close.

• Newton 217, 3476
• Curie 694, 3339
• Archimedes 1501, 1986
• Galileo 195, 987
• Carson 2122, 2052
• Tesla 2056, 1690
• Carver 330, 2481
• Hopper 148, 1678

Hooded Single Flywheel Shooters:

• 217, 3476, 694, 3339, 1501, 2056, 2481, 1678

Catapults:

• 1986, 195, 2122, 2052, 148

Double Flywheel:

• 987 (horizontal), 1690 (vertical)

Linear Punch:

• 330

This data could be the way it is for multiple reasons.

1. These are the best kinds of shooters
2. These are the most common types of shooters
3. These are the shooters that happened to make Einstein

But if you look closer at how they got there, you'll start to notice trends.
9/16 of these teams had inarguably high release points. 5/16 couldn't go under the low bar as a result of that.

These teams prioritized certain objectives, and met them 100%. It's obvious when looking at 1678 and 1690's designs that they anticipated needed a high release point, but also needed to be able to get a solo breach. They have the resources to execute that at 100%, so they did.

Other awesome teams on Einstein had other priorities above high release point.

2122 showed up at their first regional just making low goals. They then improved by adding a climber and then eventually their extremely accurate high goal shot. They did, however, shoot from almost the ground.

1986 had a catapult, which allowed for a relatively high release point that would get over most blockers while still going under the low bar.

217, 3476, and 1501 eschewed the low bar in favor of a harder to block shot and a climber.

The type of shooter you choose isn't about which is objectively "the best", but rather which one fits your priorities and resources the best.

Re: what was the best shooting mechanism for 2016?
 

To the extent of my knowledge, 2481 didn't have a climber.

Re: what was the best shooting mechanism for 2016?
 

You're correct. I edited my post to reflect that. The rest stands.

Re: what was the best shooting mechanism for 2016?
 

Thank you for this great data! I understand that we cant deifne what is the "best" type of shooter. My main goal was to see what mechanism the teams that were successful at shooting this year used. I can say about my team(3339) that we used one wheel shooter and it worked well, we've reached the consistency we were looking for but our main problem, like most of the wheeled shooters was the damaged boulders.
Again, it is obvious that we can't define what is the "best" type of shooter, this disscusion was ment mostly for sharing data and experience about the types that were used by different teams.

Re: what was the best shooting mechanism for 2016?
 

when we were looking at shoots we looked at wheels but the problem with that is ramp up time. Catapults are wishy washy. So a liner punch seemed like the best design for consistent shots. But most teams had wheels.

Re: what was the best shooting mechanism for 2016?
 

We didn't worry about ramp-up time as much because of the fact that robots can only carry one boulder. With only one boulder to shoot, you only need to make sure that your shooter gets turned on sufficiently ahead of time (for us we turned it on right after crossing the outer works). Another neat trick I've heard of is that some teams leave their shooter running at half speed or quarter speed for most of the match so it takes them less time to spin up.

Re: what was the best shooting mechanism for 2016?
 

I'm curious about how you came to this conclusion. Our catapult could shoot from any legal spot on the field.

Re: what was the best shooting mechanism for 2016?
 

I'd love to know how your catapult was powered. One of the bigger advantages to a catapult in my opinion is that you can make it have a consistent amount of power with relatively little programming by using springs, pneumatics, and hard stops.

Now there are ways to make each of these methods shoot from multiple positions, and also ways to make your trajectory flat enough to shoot from a ton of different locations with the same shot.

I'd love to hear about how some of the best catapult teams made their catapults work this year.

Re: what was the best shooting mechanism for 2016?
 

Ditto, I would love to see some more details of your catapult. I loved watching your robot put shot after shot in the high goal. I figured it was spring or pnuematic powered.

Re: what was the best shooting mechanism for 2016?
 

No springs or pneumatics. It is a fully electric catapult powered by 2 mini-CIMs. Steve describes it here:

http://www.chiefdelphi.com/forums/sh...9&postcount=47

Re: what was the best shooting mechanism for 2016?
 

Thanks I had already read that post, I was wondering if you had any additional information and pictures.

Re: what was the best shooting mechanism for 2016?
 

This side view shows the catapult arm after it has reached its most forward position and has begun to retract:



The arm is nearly the length of the robot and pivots on the front frame rail. It's driven by 2 mini-CIMs through a toughbox mini and #25 chain with an overall ratio of 28:1. We have an incremental encoder on the gearbox so we know how far its traveled is each 20mS control loop.

I don't remember the exact weight of the catapult arm but it is extremely light. The arm itself is 1.25" square, 0.040" wall thickness 7075 tubing that came out of a sponsor's dumpster. The "dish" the boulder rests in is carbon fiber. The block of pink foam on the arm was added after week 3 and reduced the boulder settling time substantially.

Re: what was the best shooting mechanism for 2016?
 

The best Shooting mechanism was 971 Spartans shooter would retract and it had probably the vison tracking. Don't teams like 16, 1678, 1538, and others who had good rotational platform which made them "UNBLOCKABLE".:ahh:

Re: what was the best shooting mechanism for 2016?
 

While we may not be able to compete with teams like 254 or 971 in shooter design, we at 2877 are proud of our Pnuematically fired rolling catapault.
Our biggest innovation was the placement of servos on the end of the shooter tips. Combined with vision code, this gave us the ability to precisely control the distance and arc of the shot. As our vision code evolved, we came to the realization that by putting the servos at different angles we could aim the ball to the left or right which reduced our time to shoot greatly.

Attachment 20786

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Re: what was the best shooting mechanism for 2016?
 

Now that's really cool. Do you have some videos of this in action? We'd joked about changing our left/right shooter speeds during the season to create a curveball, but never thought about really trying it.

Re: what was the best shooting mechanism for 2016?
 

Wow. That is really cool. Did you guys win any awards for that specifically?

I also just wanted to comment on this. We had this same conversation in our team, and it went from joking, to half serious, to actually trying it. We probably spent about 2 hours trying to get a curveball to work with our dual wheel shooter, and while it did curve a little, the shot power was reduced a lot, so we scrapped the idea of using it. Would not recommend.

Re: what was the best shooting mechanism for 2016?
 

Most of the boulders I saw used on the fields were in like new condition. If a boulder got a big tear or rip during a match they would replace it with a new one. I don't think one is better then the other, I think its more of what works best with your team. I think one of the reasons we chose a wheeled shooter this year was because we have done them before and have experience on how to tweak and adjust them.

Re: what was the best shooting mechanism for 2016?
 

Brand new balls still performed differently than slightly used balls.

Re: what was the best shooting mechanism for 2016?
 

Unfortunately, I don't have any close up video(might try to get some at our next meeting), but you can see a pronounced difference in how long it took us to line up at each of our events.
At WPI, our first district event, it was taking us around 6-7 seconds to line up and shoot(Our robot is on the blue alliance shooting at the center goal)

At our next event, BU, it was in the 3-5 range(robot on blue alliance shooting into near goal)

At NEDCMP, our final event, with the "Differential Flaps" fully implemented, it was 1-3 seconds depending on how close our angle was before we let the robot take over. Our robot is the robot nearest to the center goal


We won Innovation in Control at BU and NEDCMP

Re: what was the best shooting mechanism for 2016?
 

That's ridiculously cool. It's also a great solution to getting hit while shooting if you can't seem to get a shot from a more protected location work.

Re: what was the best shooting mechanism for 2016?
 

Thanks so much! The "Differential Flaps" were implemented in response to playing under heavy defense(shoutout to 2262 for indirectly causing our shooter to improve). Our catapult didn't have the capability to shoot from the outerworks or the batter accurately, so we opted to quick-shoot.

Overall, our season ended in a slightly disappointing fashion, as we were ultimately brought down by our tread failure, and missed out on a trip to Saint Louis. Overall the season was great, but it was somewhat disheartening to think about how good our robot could of been with a better drivebase.

We are in the process of improving the drivetrain and hope to be playing at our peak at BattleCry this weekend.

I suspect our programming team will write up a whitepaper detailing everything about our code and vision tracking for anyone interesting in the nitty-gritty detail

Re: what was the best shooting mechanism for 2016?
 

I've been thinking about this thread again, and I decided to analyze IRI this time as a sampling of the best teams in the world ought to produce the best shooters as well, right?

IRI had:

• 26 Single Flywheel Shooters
• 21 Catapults
• 11 Double Flywheel Shooters
• 2 Linear Punches
• 9 Robots without a high goal shooter
• And 1619's shooter, which I'm not quite sure how to classify, but it used a lot of wheels. If someone from 1619 would comment, that would be cool.

Of those teams, in eliminations were 32 teams as follows:

• 14 Single Flywheel Shooters
• 7 Catapults
• 4 Double Flywheel Shooters
• 2 Linear Punches
• 3 Robots with no high goal shooting
• 1619

There are a few ways to analyze this data, so I've put it into a little table. The first one is the number of teams with that type of shooter compared to the total number of teams at IRI. The second is the number in eliminations with that type of shooter compared to the number of teams at IRI with that shooter, and the third is the number of teams in eliminations with that type of shooter relative to the total number of teams in eliminations.


This data could mean absolutely nothing, and the shooters at IRI could be happenstance and good teams just happened to draw their inspiration from 2012 robots or something. Or maybe not.

I think the most interesting numbers are the comparison between the first row and the third row. Despite being the largest group of robots at IRI, single flywheel machines were over-represented in eliminations, while the next three largest blocks(Catapult, Double Flywheel, None) were all underrepresented in eliminations. The middle row also represents that, with more than 50% of all single flywheel teams at IRI making eliminations.

Knowing this information (and also my experience in the past with some very finnicky double flywheel shooters and catapults), I would use a single flywheel shooter in a similarly styled shooting game in the future (although God knows I'm going to eat these words when I want to pursue some other shooter a few years from now and my students do some research and find this post).

Re: what was the best shooting mechanism for 2016?
 

Very cool data you have here! I'm happy to see that 100% of teams with a 1619 style shooter made it to elims, haha. Anyways, on to our shooter design.



Basically, two horizontal rows, each with four four inch colsons, opposite from quarter inch polycarb, with about 2 inches of compression.

Personally, I most enjoyed watching (and listening to) the linear puncher shooters. However, different shooters entail different constraints and/or requirements, and can all yield great results when well optimized.

Re: what was the best shooting mechanism for 2016?
 

Really interesting writeup. Could you post the lists of which teams use which shooting mechanisms? I'd like to take it one step further and see how far the various mechanisms made it in elims.

Re: what was the best shooting mechanism for 2016?
 

Well lets take a look

Winning Alliance
2056 - Single Flywheel
118 - Catapult
33 - Single Flywheel
4587 - Catapult

Finalist Alliance
1114 - Single Flywheel
195 - Catapult
225 - Dual Wheel
1405 - Defender

Semi Finalist 1
1619 - 1619 Style
1241 - Single Flywheel
133 - Catapult
868 - Single Flywheel

Semi Finalist 2
3620 - Single Flywheel
67 - Single Flywheel
3683- Low Goal
5254 - Dual Wheel

Quarterfinalists 1
2771 - Single Flywheel
16 - Single Flywheel
1024 - Catapult
1023 - Single Flywheel

Quarterfinalists 2
217 - Single Flywheel
2451 - Catapult
494 - Single Flywheel
3641 - Dual Wheel

Quarterfinalists 3
2481 - Single Flywheel
330 - Linear Punch
3824 - Dual Wheel
1640 - Catapult

Quarterfinalists 4
45 - Catapult
179 - Single Flywheel
1806 - Linear Punch
233 - Low Goal

I am probably wrong somewhere in this list so if you see something wrong just PM me and Ill edit it.

Re: what was the best shooting mechanism for 2016?
 

Analyzing how many of each type of shooter there was is similar to counting how many presidential candidates have blue eyes. The quantities of each might represent what teams initially perceived would serve them the best, but that decision making process was full of other variables like packaging, previous experience, and fabrication difficulty.

If you want to determine which was superior, then you need to determine what metrics you believe are important to the shooter and measure them.

% shots made would be a decent start.

Re: what was the best shooting mechanism for 2016?
 

Here is data on this subject from our qual match scouting at IRI. The usual noise of scouting data applies.

Re: what was the best shooting mechanism for 2016?
 

Very true, but I think it's a good start, and it's an easy analysis to do.

Re: what was the best shooting mechanism for 2016?
 

Best Shooting mechanism of 2016: Robonauts Grappling Hook

'Nuff Said

Re: what was the best shooting mechanism for 2016?
 

Thanks for the kind words. Your last sentence noted above is worthy of emphasis.

Having previous experience with hooded shooters (2012) and linear punch shooters (2014) we considered both before settling on a catapult design. Given the packaging constraints imposed by our desire to hang, be low bar capable and retain low and high goal scoring, our small spring catapult emerged as the best solution for us. Additionally, our picker design permitted us to quickly move the ball from low goal scoring position to catapult and back again if required by defense robots.

In terms of accuracy, on Carson through Einstein high goal accuracy was 79%. With respect to our low release point and its vulnerability to blockers, we experienced 2 blocked high goal shots out of 80 taken in teleop throughout CMP's.

Re: what was the best shooting mechanism for 2016?
 

Any reason why 1619 has their own group?

Re: what was the best shooting mechanism for 2016?
 

Because even after a member of 1619 posted a picture and explained their shooter, it is unique enough that it doesn't quite fit in any of the other groups. It could probably be grouped with the double flywheel shooters, but it's enough of an outlier to earn its own category.

Re: what was the best shooting mechanism for 2016?
 

We had the same shooter design (more or less).

I'd classify it closer to a single wheeled rotary shooter than a double flywheel shooter.

It's using flywheel(s) on one side to roll ball against a stationary wall and has a good deal of travel on the ball. A double wheeled shooter reacts off both wheels at once and doesn't have as much travel time on the ball.

Re: what was the best shooting mechanism for 2016?
 

Well that shows how unique it is (or how dirty my glasses are). I thought it was the blue wheels on the two vertical shafts that provided the power, not the horizontal rows of Colsons. I guess those are for intake then.