Launcher Types, The Great Debate of NBN

VEX V5 General Discussion General Forum
1

This thread is designed to do the following: Help teams whether experienced or not with launcher designs, help improve launcher designs, and to come up with new launchers (if possible). Below I am giving the main designs that have been introduced this year. The pole is for what design you think is best not what design you have. All credit for the videos goes to there sources.

To start off with the most common type of launcher, the dual flywheels:

The dual flywheels are 2 wheels set beside each other or above each other that spin at a target of 2400 - 3000 RPMs. The housing of the flywheels is usually stood horizontally (which gives better accuracy) but in some cases stood vertically (gives better distance). The best gear ratios are: 7:1 with turbo motors, 15:1 with high speed motors, 21:1 with high speed motors. The fallowing are videos of the dual flywheels, all thanks to there origins:
929w
26
35
and many more that will not be shown.

https://lh6.googleusercontent.com/-PoCHWvp0v1k/VivK6laVC8I/AAAAAAAAATU/fJk8088UTbI/w826-h617-no/IMG_4185.JPG

Next is the single flywheel, with the fastest recovery time. This was pioneered in vex by 8059:

The single flywheel is a wheel that spins at a target speed of 2800 - 3200 RPMs. The ball can be entered on the top or bottom. Some teams have the ball switch directions with a bent piece of metal the goes around the wheel. The best gear ratios for this are: 35:3 with turbo motors, 21:1 with high speed motors, 25:1 with high speed motors. This design has been the fastest at recovering its full speed in about 0.7 sec. (respectively). The best examples of this design are:

8059a
323z

The next design is the hardest to perfect but is very rewarding, as we see with team 62’s pinball launcher. This design is the catapult, whether it be a Wingus and Dingus catapult or pinball launcher, they are all catapults:

The catapult is a design that pulls back rubber bands by the means of a cam gear (or any other means), after the piston or foot releases it hits the ball and sends it flying. This is the most accurate design, as we see in team 62’s documentary video. The design works best with cam gears. The drive gear ratio depends on the rubber banding. Below are the best examples of these launchers, all credits go to the origin of these videos:
62
7682

So the real question is, what is the best launcher. The dual flywheels shoot the farthest, the single flywheels ramp up fastest, and the catapult is the most accurate. Well, that is to be decided (or made more clear) by this thread. So what do you think?

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I don’t think that you can say which design is better because it varies based on the strategy of the robot (loading zone shooter, position tracking field shooter, or “against the bar” field shooter). Also, when you say “7:1 with turbo motors” is that an overall gear ratio of 7:1 or 18.2:1?

3

Well tink back to last year:rolleyes: in skyrise, at the start of the year we were asking “which is better, a skyrise builder or a cube scorer”. At the end of the year we saw that there were teams (like 62 or us or the New Zealand teams) building most of the skyrise in auton. By the end of this year the preload may be gone in 20 sec :eek:. My point is what design will do all of them the best. Also when I am refereeing to the 7:1 gear ratio I am meaning the external gearing.

4

Just so you know there are already teams that can do the preload in <20s with both flywheel and catapult-esk designs.
Here are some vids 8000 took during Dougherty
- YouTube - 5776T ~20s (fairly accurate)
[- YouTube - 5327C ~15s (had some problems during the tournament)](- YouTube - 5327C ~15s (had some problems during the tournament))

5

Ok cool, I had not seen that yet. I guess my prediction was correct;).

6

First off thanks for mentioning us :)! Also I do agree with a lot of things you said, but here’s my 2 cents. My team started off thinking that our dual flywheel was going to be temporary and help us gain experience to build a single flywheel. However, we have had huge success with this design and we are currently working on a way to almost double (in theory) our fire rate.

So the short answer is that there really is no right answer, if you build it right it’ll work.

7

That second video’s robot shot WOW fast but pretty inaccurate, that team is going to be a monster when their accuracy catches up to their speed

8

I think in the end it depends on how much time you put into your design. Any of these designs can be made awesome with enough tuning. They can become really accurate and really fast with the right design choices.

9

Ohhhhhhh, 5327C is quite accurate all right. One of the problems at the tournament was that the balls were quite literally as hard as baseballs, which affected the flywheels quite a bit. The balls on the skills field were much much softer–there’s a reason they’re the top PS and almost top RS in the world right now :slight_smile:

10

Well, what ever the balls were like, that robot is amazing! But I still think that there will be one dominate design this year. Last year it was the scissor lift and double reverse 4-bar. Toss Up it was the 6-bar etc. My personal opinion is that the single flywheel is the best design.

11

Maybe I’m being picky, but it looks like there’s a mechanical difference between the catapult and pinball mechanisms.
[ATTACH]9747[/ATTACH]

Edit:
Catapult - Rotational motion
Pinball - Linear motion
Picture1.jpg

12

Heres my 2 cents.

I think what we are going to see the most is flywheels. They are probably the easiest to build and perfect, not to mention the best documented. You can build a single flywheel 8059a style robot and push out balls at 2+ balls per second.

I think as designs have progressed, ‘two sided’ flywheels have become essentially obsolete compared to their single counterparts. I mean for what we have seen, single flywheels are at least quite a lot faster. EDIT: I see a lot of people have voted double, whats your reasoning? Im quite interested. :smiley:

My personal bet is on catapults, I think a team that can design a fast, accurate catapult that can shoot full field, mid field and close to the net all with good accuracy could do really well.

Pin ball machines… well I haven’t really seen anyone do them apart from cam :stuck_out_tongue: Sooo… Maybe? :smiley:

13

You are not being picky. You are right.

In fact, think I am even pickier. There is a difference between pinball and crossbow as well :smiley:
Both are linear motion, but the point of transfer of momentum/energy is different.

14

That brings up an interesting point, I have not seen any crossbow, sling, or other medieval designs yet besides a catapult. has anyone else?

15

I haven’t seen any ballistas or other medieval siege weapon-inspired launchers yet, but my team is working on a ballista that doesn’t need custom nautilus gears. When we finish our robot, we will do a reveal.

16

I think that the catapult will do well, although it will require some power. The reason for this is because of its consistency. I have made a catapult and although I have a 1.2 second firing rate, I have consistency. I have made 40 balls with 99% accuracy. The reason we barely missed was because of a user error of loading the ball.

17

I actually don’t believe we will see many crossbow or sling type launcher becoming mainstream. The problem with those designs is the fact that the ball must be loaded either right before or right after the sling is loaded. However, if it is done before, the sling still needs to **** back. If it is done after, the loader must wait for the sling to **** back before loading. Either way, it isn’t as efficient as a puncher, where the loader can load the ball while the puncher is cocking back.

18

I personally like using the double flywheel, but there are certainly some disadvantages to using them. It’s difficult to maintain a high fire rate, keep both wheels at the same speeds without gearing them together, and overall size of the mechanism.

Single flywheels take up less space and have a higher fire rate, but require MUCH more refining and engineering to use effectively.

I have not personally made a catapult or pinball launcher so i cant give much input on them.

19

Why is it bad to gear the two sides of the flywheel together?

20

It is not necessarily “bad”, but it will make the gearbox massive to keep the 6 or 7 hole spacing and keep the wheels spinning in the opposite ways. I believe good construction and a solid P correction is key to double flywheels. The same RPM on both sides is required (unless you’re going for a curve shot :p).

I like single flywheels because of the rapid fire rate achievable through fine (very, very fine) tuning.