I totally agree. The puncher is much better for loading purposes, but it does rely more on the ball’s compression. If you are concerned about the difference in compression, the catapult is the way to go, as it is unaffected by a ball’s compression. However, the main issue is loading it. It is very difficult to load a catapult consistently besides when it is at the bottom. And when it is at the bottom, it definitely isn’t easy to make sure that you are loading it consistently, especially if you don’t have a wait at the bottom.
Regarding a puncher and how much it is affected by a ball’s compression, the distance is affected more than I could have expected. With a firm ball, the ball easily made it into the high goal. With a noticeably softer ball, the ball hit a few feet below the high goal, which really surprised me.
At Worlds, I think that balls will at least be fairly new throughout, meaning that they will probably have similar “firmness levels”. However, at regional competitions, most teams can probably expect a wide variety of newer, more firm balls, and older, more soft balls, especially as the season progresses.
With the debate on which launcher is better, here at 1138, 1138A uses a single fly wheels positioned vertically, 1138 B uses a cam driven catapult while 1138G uses dual fly wheels horizontally. We have noticed that 1138B with our cam driven catapult have had exceptional accuracy while 1138A and G being not as accurate. We have also noted in competitions that punchers and catapults have been more accurate than fly wheels and have scored higher.
I think there are actually a number of ways to initiate a passive release mechanism without custom cutting a plexiglass sheet. I have thought of at least 3, although 1 is impossible with VEX. The question at this point becomes how much of an issue are the variable ball density rates, because we all know that a plunger is more efficient than a catapult (team 62 got it working with a 1 second fire rate and 2 motors.) At a competition I went to this weekend, two teams, who I will not give the name of for anonymity, both with custom cam shooters, were the tournament champions and had about a 1 second fire rate with 85%ish accuracy. However, another robot on the alliance that lost in the finals had a different kind of passive release mechanism that was able to achieve an even faster fire rate with but with only 70%ish accuracy. If VEX decided not to perform any quality control at some competitions and lots at others, we may see some teams dominate at certain events and fall on their faces at others. In any case, VEX has to a large extent fixed the varying ball compression rates to my knowledge, so it may not be an issue at all.
Interestingly enough, at a regional competition I went to but did not compete in a few weeks back, team 62 switched to a single flywheel and was able to accomplish at 0.75 second fire rate but with much worse accuracy than the cam shooter. Given that they were able to get a 1 second recovery rate with 2 motors and were using 4 motors on their flywheel, the only logical reason to switch to the single flywheel would be because the cam shooter does not, in fact have good accuracy. Perhaps this will change now that the ball densities have been fixed?
In any case, perhaps plungers, with cams or other passive release mechs, will dominate at higher levels because of their increased efficiency.
But, to play devil’s advocate, team 9674 in China was able to get an even faster fire rate than the cam shooter, at about 0.65 seconds per shot. And 323Z said in a forum post that they have an 0.625 second recovery rate with their single flywheel.
So, maybe the piston shooter is more efficient, but flywheels are just as good? The convergence that we saw in design last year as better teams advanced will be interesting to see this year with NBN. In any case, there will be an emerging answer to this question as the season goes on.
Recently I have tested out a single flywheel, this is totally my favorite design:cool:, it is so accurate. When launching the full field it would only vary about 1" in each direction, out of 25 balls we only missed 2 balls that were bad and ripped up. It also ramps up very fast. Though I have not yet timed the recovery time, I am loading the balls in continuously.
our team has a 1:7 gear ratio with 4 motors all with turbo gears and are redoing our intake… if were to increase power in the program and make the angle less steap would that change my distance from where i shoot or not?
What type of launcher are you using and how far can you shoot already? If you are barely scoring from the starting tiles you should just increase your power a bit.
My launcher can shoot full field using 70 with the same gear ratio, but our angle and launcher is most likely different from your’s, so you may have to add or take away a bit of speed depending on where you want to shoot from. I don’t know our exact angle but I will post a picture below as a reference.
From testing, we found that the sprocket would get up to speed faster than a regular wheel 4" wheel and would not lose as much speed when a ball is shot. Also, it helped solve much of our flywheel’s vibration issue.
The tank treads are just there to help with the compression and placement of the rubberbands.
Because there is less weight on the sprocket and tank tread than there is on the large traction wheels, wouldn’t there be a bigger slow down each time you launch a ball because there is less than mass and therefor less momentum?
It should slow down more because there is less mass, but it doesn’t. The weight of the 4" wheels caused the whole launcher to vibrate which resulted in friction being added to the launcher which slowed down the motors more than it should whenever we launch a ball.
If it wasn’t for our poor build quality when designing our dual flywheel, we would have been able to keep the 4" wheels.
If you have a dual flywheel, you should try out the sprockets and post your results.
Alright, thanks i actually have a single flywheel but am thinking about testing a sprocket and chain wheel on that after our tournament this Saturday, to reduce compression on the balls
