I remain inspired by Ether and his apparent passion for mathematical modeling (PLEASE COME BACK!). In that light, please use this post to aggregate information related to modeling the ballistics of the Infinite Recharge POWER CELL shot.
My team has yet to measure the POWER CELL drag or lift coefficient so if anyone has made a ball drop experiment, I’d be particularly interested in that result!
(for this game) I agree drag and lift could be negligible, but I like including it in the math! This sheet was 100% inspired by previous posts by ETHER. Let’s continue to “Do the math” so we can “Save the World!”
This is a bad assumption for a spinning sphere, especially if you want to go for a 3/4 field shot.
The Apocyphal Wisdom is to slap some backspin on it for a flatter trajectory.
I’d love to see some real trajectory mapping and modeling, but I need to build our field first so we can run experiments.
Bit of a shaky cam, but this is some trajectory tracking we did today.
Its a bit fast on the gif, but Vx is dropping over a roughly 6m displacement. Roughly 16-19 m/s^2.
We did some lob throws as well and got much lower drag accelerations, but for those looking to shoot from a fair distance, expect to wrangle with the shooting dynamics.
In computer science last semester, we built a ball launching simulator that took into account all factors, including the Magnus force, and used a genetic algorithm to determine optimal speed and launch angle to hit a goal. We’re currently working on adapting this solution for the game.
@sgeckler’s calculator should be more accurate than mine because it takes into account drag and lift, which mine doesn’t. I’m curious to see how far off I was though. Also, magnus effect is definitely non-negligible on these balls! I’d love to see someone modeling magnus effect properly.
Ball velocity is just that, the velocity of the ball when it leaves the shooter. I’m essentially assuming that the ball appears at a specific location (0, y) traveling at the specified speed and angle. For a two-wheeled shooter (zero spin), the ball velocity is the surface speed of the wheels. For a single wheeled (hooded) shooter, the ball velocity is roughly half of the surface speed of the wheel (although it depends what the backing of the hood is made of).
So looking at this, the curve represents the height of the ball and the lines represent the height of the goals. The places where the curve is in between the lines (the ones which determine the goals upper and lower bound) is from where you can shoot from and have the ball land into the target. Correct?
What motors do you use, what RPM do you want to run them at, and how are they geared?
What is the MOI of the shooter wheels?
And includes a handly single-variable bisection algorithm to find the right RPM or hood angle for a given shot. You can adapt to whatever…
And includes a handy rev-up-time simulator (so you can figure out how many motors you need, how adding inertia will help your shot but hurt your response time, etc…)