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Flywheel RPM Drop & Recovery

How much speed each shot costs, how long until the wheel is ready again, and therefore how fast you can 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.

1
2
3
4
5
sec

Indexer cycle time. Runs alongside recovery, not after it.

%

How close to target counts as ready. Tighter means slower firing but more consistent shots.

kg·m²

Optional. Only needed for the energy figure, and only trustworthy if you measured or modeled 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

—

Fire four in a row

Fire four in a rowflywheelindexer
0%

Four shots at the fastest steady rate your numbers allow. After every shot two things happen at once: the flywheel climbs back to speed, and the indexer loads the next object. The next shot waits for whichever finishes last, and that one is your bottleneck. Only your measured times are drawn; nothing is guessed about the shape of the climb.

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 shots

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.

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                                  Comes after

                                  Shooter Accuracy & Consistencygives you your trial resultsFlywheel Design Studiogives you your flywheel speedShooter Type Comparatorgives you your cycle time

                                  You are here

                                  Flywheel RPM Drop & Recovery

                                  Where your answer goes

                                  Flywheel Design Studiosee how extra spinning mass would shrink the speed drop on each shotShooter Accuracy & Consistencycheck whether the speed drop makes your shots land in different placesuses your trial results againShooter Type Comparatorcompare your real fire rate with what other shooter types could reach

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