The nine metrics on every arrow
After each release, the Post-Shot Telemetry panel reports exactly what the engine calculated. Each number maps to one link in the chain from bow to face, so each one points to a different fix.
| Metric | What it measures | What it diagnoses |
|---|---|---|
| Draw Strength | Draw fraction at release | Draw length consistency |
| Wind Compensation | Aim-off as a share of actual drift | Wind reading and hold |
| Arrow Velocity | Launch and impact speed | Energy loss to drag |
| Flight Time | Nock to target plane | Exposure to wind and gravity |
| Ring Score | Scoring ring, X for inner 10 | Outcome |
| Distance from Centre | Radial miss in cm | Precision |
| Launch Angle | Sight mark plus aim elevation | Vertical aim discipline |
| Kinetic Energy | ½·m·v₀² at launch | Draw quality (scales with d²) |
| Wind Drift | Lateral push versus calm-air flight | Conditions at release |
Mean point of impact
A single arrow can lie; a group cannot. The mean point of impact (MPI) is the average position of all arrows that reached the face. It separates two very different problems: an offset group that is tight but away from centre, and a centred group that is simply too wide.
MPI = ( Σxᵢ / n , Σyᵢ / n )If the MPI sits more than one ring width from centre, the error is systematic — a repeatable bias such as a consistently short draw or an uncorrected crosswind. Systematic errors are fixed by adjusting the sight or the hold. If the MPI is close to centre but arrows are scattered, the error is random and must be fixed through technique: steadier holds, cleaner releases and better timing in gusts.
Radial spread and group size
The match panel's Avg from Bullseye is the mean radial distance of every arrow on the face. It blends bias and scatter into one figure. To isolate scatter, measure each arrow's distance from the MPI rather than from centre:
σ_r = √( Σ[(xᵢ − x̄)² + (yᵢ − ȳ)²] / n )On the 122 cm face at 70 m, a σr of 6 cm — about one ring width — keeps a centred group mostly in the 9 and 10. A σr of 12 cm spreads the same group into the red. Because ring width is fixed, halving your spread is worth roughly one ring on average across the match.
Draw and wind consistency scores
Two telemetry lines deserve their own tracking column on your scorecard. Draw Strength should read 100% on every arrow; at 70 m each 1% short costs about 13 cm of elevation, so a single 98% draw can outweigh an otherwise perfect shot. Wind Compensation should cluster between 80% and 120%. Consistent readings near 50% show that you are under-reading the flags; wildly varying readings suggest you are releasing at random points in the gust cycle.
- Draw index: count arrows at 100% draw out of ten. Target: 10 / 10 before moving distance.
- Wind index: count arrows with compensation between 80% and 120%. Target: 7 / 10 in variable wind.
- Vertical index: compare Launch Angle across arrows. At 70 m, a spread wider than 0.10° is two rings of vertical scatter.
A data-driven progression plan
Progress fastest by changing one variable at a time and moving on only when the numbers say you are ready.
| Stage | Setup | Pass criterion |
|---|---|---|
| 1 · Foundation | 18 m, calm | 90+ with draw index 10 / 10 |
| 2 · Mid range | 30 m and 50 m, calm | 85+ at both distances |
| 3 · Wind intro | 50 m, variable | 80+ with wind index 7 / 10 |
| 4 · Long range | 70 m, variable | 75+ and avg from bullseye under 10 cm |
| 5 · Elite | 90 m, gusty | 70+ with at least one X |
Lab habit: after every match, write down the total, the MPI direction, the draw index and the wind index. Three matches of notes reveal patterns that a hundred unrecorded arrows never will. With functional storage enabled, the range keeps your personal best at each distance on this device.