Flywheel RPM Drop & Recovery
How much speed each shot costs, how long until the wheel is genuinely ready again, and therefore how fast you can actually fire.
Inputs
One row per shot. Read the numbers off the brain or a logged graph: the speed just before firing, the lowest it dipped to, and how long it took to climb back.
Indexer cycle time. Runs alongside recovery, not after it.
How close to target counts as ready. Tighter means slower firing but more consistent shots.
Optional. Only needed for the energy figure, and only trustworthy if you measured or modelled it.
Results
Sustainable fire rate
—shots/sec
Time between shots
—sec
Average drop
—RPM
As a share of target
—%
Average recovery
—sec
Shot-to-shot variation in drop
—RPM
Energy per shot
—J
Only if inertia is given.
Shots recorded
—
How this is calculated
Every shot takes energy out of the flywheel, and the wheel slows down. Fire again before it has climbed back and the second shot leaves slower than the first, which is why a shooter that is accurate on the first ball sprays on the third.
The rate that actually matters
time between shots = the longer of (recovery time, reload time) fire rate = 1 ÷ time between shotsWith your numbers
Recovery and reload happen at the same time, so the cycle is set by whichever is slower rather than by their sum. That tells you where to spend effort: if recovery dominates, a faster indexer buys you nothing.
Drop is about stored energy, not motor power
How far the speed dips is decided by how much energy the wheel was holding compared with how much the shot takes. A heavier wheel, or one spinning faster, dips less. The motor barely affects the dip at all; it only affects how quickly the wheel climbs back.
So the two symptoms have different cures. A large dip wants more flywheel inertia. A slow recovery wants more motor power or less reduction. Adding motors to fix a large dip is the usual wasted change.
Consistency is the real score
The variation between shots matters more than the average. A wheel that drops 400 RPM every single time is predictable, and a program can wait a fixed interval and be right. A wheel dropping anywhere between 300 and 600 cannot be waited out reliably, and that unpredictability shows up directly as scatter on the target.
If the variation is large, look for inconsistent object compression, a belt slipping, or a battery sagging as the match goes on.
Sources & assumptions
No VEX data is used. Everything is computed from speeds and times you record, so nothing here goes stale between seasons.
The energy figure uses ½ I (ω₁² − ω₂²) and appears only when you supply an inertia. VEX publishes no inertia for any assembly, and it depends entirely on what you built, so this tool will not guess one. Without it the drop and recovery figures are still complete and useful on their own.
Assumes recovery and reload overlap, and that you measured the true minimum speed. Sampling too slowly will miss the dip and make the shooter look better than it is.
Save this run, and compare
Keeps what is on screen so you can change something and see both sides of the change. Saved in this browser only, never uploaded.
Save this as evidence
Collects what you entered, what came out, how it was worked out, and anything the tool flagged, with a timestamp and a version so someone else can reproduce it.
This is evidence, not a notebook entry. It deliberately does not write your problem statement, your reasoning, or your conclusion, because under RECF rules an Engineering Notebook has to be the students' own work and no tool may generate or organise its content. Take the numbers, decide what matters, and write it yourself.