New Catapult Design?

Has anyone thought much about Wingus and Dingus’s new design (ChooChoo shooter)?


It only uses two motors and its another catapult.
Tell me what you guys think.

Interesting design. I personally try to stray away from catapults because you constantly lose potential energy as the ball loses height. I am a fan of slip gear with a stop that actually prevents the ball from moving in any direction.

However, I do like the idea of using tension and a lever arm to be able to launch a ball. Possible problems that I could see is trying to work with the tension that over time will conform to the length that it is stretched. If all these problems were fixed, this would still have the potential to be a very accurate and fast launcher. I would still prefer this in comparison to dual flywheel. Flywheels, when perfected, have the capability of being the number one deadliest launcher in the game. If they have a very small reload speed, accurate shooting through the use of PID, and fast firing speed, they could whoop alot of people. However, this is very scarce. Linear punchers, lever arms, and catapults are a lot easier to use and program, and they still can prove to be intimidating.

In the end, we’ll see the victor at nationals and worlds.

I have found that catapults have the highest accuracy of any launcher, whether puncher, flywheel, or anything else. However, because of the extra energy catapults require to propel balls into the high goal, the entire robot suffers from shock, jumping forwards every shot and requiring readjusting for the next shot. This readjustment wastes a ton of time, effectively eliminating the benefits of a catapult. Another issue is loading a catapult. Catapults are not easy to load via mechanisms, and while teams have pulled it off quite well, the process is much slower than loading a flywheel or puncher. This also brings up the limited fielding capabilities of many catapults, such as catapults powered by slip gears or the “choo choo” mechanism, since these can only score from one place.

We saw a lot of teams do this in frc and built a prototype a month ago. The linkage style was just too space inefficient for us. And we like flywheels better. We stopped all work on our current competition robot and have been making a 4 sided rubber band intake with a pivoting turret and climber. We find that flywheels, while definitely slightly worse in general at full court, arnt as good on the feild, and are easy to defend against.

Yeah. I was going to try it out, but then automatic feeding would be very hard, and hand feeding during the match can be very unreliable.

I agree with you, powerful slip gears and other launchers using a lever arm with dynamics will often shock the robot to make it need to readjust itself. Something to consider perhaps using a system that could reduce that shock or get rid of it all together. Also, what would your team altogether go ahead and classify as a slow firing rate?

We had a choochoo puncher. But we dismantled it.
I was concerned with the high maintenance involved. But maybe it is due to the not so great quality of build.

With our catapult, it took over a minute just to shoot the preloads, but we had 100% accuracy. We then built a double catapult, but the entire robot jumped forwards enough that after ~3 shots we would move out of the loading zone. We have since moved to a rotational puncher.

Just add a ton of weight to your robot to prevent it from jumping.

At this point in nbn, fielding ability is as important as shooting match loads. Adding a ton of weight kills the fielding ability, which of absolutely necessary.

Maybe a lot of weight and a lifting mechanism so you’re stable and not jumping backwards and you can still do 2 of the 3 functions.

In my opinion, fielding ability is more important than lifting since it offers more potential points. In addition, there are other designs that offer consistent and fast full court shots that are more compatible with more subsystems.

Maybe if you add lots of padding the robot will not jump around as much

You could just separate the launcher from the rest of the robot using a suspension system, which would prevent jumping. I’m thinking leverage suspension, such as what full suspension mountain bikes have.

Adding a suspension adds a level of inconsistency to the system that each shot can be very different from one another, thus eliminating the high accuracy the catapult gives.

Indeed… I hadn’t thought of that. (I’ve never built a catapult.)

So the question is, how far does this shoot? I built a catapult that shot at a rate of 0.3 secs. but it only shot 5-6 feet. If this shoots the whole field than this is impressive.

As a stop, maybe rubber bands stretched tight (not too tight, just a tiny bit). I’m not sure what that would do to accuracy, but it should reduce jumping significantly. The rubber bands would dissipate energy over a longer period of time. Since


F = ma
and
a = Δv / Δt

increasing t reduces a, which reduces F. That means that at any given time, the catapult, stop, and robot are experiencing less force. You would limit fire rate, but will keep the robot functional, which is good.

According to comments on the video and the video description, this shoots full court.

speed = Velocity, weight = Mass;
I hear this correlation between mass and speed mentioned like this often, which would be V=F/M,
or F=MV, but physics says F=MA not F=MV (edit)

Pick a representative distance, like 3 feet.
Run a series of timed drag strip race the clock, with various extra mass added.
This would look great in an engineering notebook.