Disclaimer: these calculators are as close to accurate as possible but they are not 100% perfect, use with caution.
Tip Speed Calculator copied from Bristol Bot Builders
Wheel speed
Calculate drive speed from wheel size, motor RPM, and gear ratio.
Inputs
Target checker
Speed results
Target status
Tip speed & kinetic energy
Spinning weapon tip speed and rotational kinetic energy.
Battery & motor
Weapon geometry
Results
Battery runtime
Runtime estimation, discharge safety, and pack planning.
Battery
Motor load
Match planning
Runtime
Discharge & packs
Motor power & torque
Characterise a brushless motor from kV and stall current.
Motor inputs
Custom operating point
No-load speed
Torque & power
Operating point
Weight budget
Track component weights against your class limit.
| Subsystem / component | Name | Qty | Unit wt (g) | Total (g) | Total (kg) |
|---|
Gear ratio optimizer
Back-calculate gear ratio from target speed, or verify a chosen ratio.
Motor & wheel
Back-calculate from target speed
Back-calculate from wheel RPM
Verify a chosen ratio
Ratio sweep (1.0 – 5.0)
| Ratio | Wheel RPM | ft/s | m/s | mph |
|---|
Weapon spin-up time
Estimate time to reach full weapon speed from rest.
Motor inputs
Moment of inertia
Spin-up results
Spin-up benchmarks
| Target | Time (s) |
|---|
ESC current headroom
Check motor current demand against ESC ratings — three channels plus system total.
Total system draw vs battery
Spur gear centre distance
Calculate centre-to-centre distance from tooth counts, or find required tooth counts for a given centre distance. Works for both MOD (metric) and DP (imperial) gears.
📐 MOD (Metric)
① Centre distance from tooth counts
② Tooth counts from centre distance
📏 DP (Imperial)
① Centre distance from tooth counts
② Tooth counts from centre distance
🔄 MOD ↔ DP converter
Brushless arm calculator
Design a brushless-driven arm, flipper, or lifter — motor through multi-stage gearbox to tip force and speed.
Motor inputs
Gearbox — up to 9 stages (leave unused stages as 1)
Arm geometry & travel
Motor output
Output shaft (after gearbox)
Arm tip
V-belt calculator
Calculate belt length from centre distance, or find centre distance from a standard belt length.
Belt section & pulleys
① Belt length from centre distance
② Centre distance from belt length
Pulley geometry
Standard belt lengths — 4L
| Belt no. | OD length (in) | Length (mm) | C-C (mm) |
|---|
Chain length calculator
Calculate chain links needed for a given centre distance, or find centre distance from a known chain length.
Chain & sprockets
① Links → Centre distance
② Known links → Centre distance
Sprocket geometry
Wrap angles
Link count sweep (± 4 links from calculated)
| Links | Length (mm) | C-C (mm) | C-C (in) |
|---|