Arrow setup analysis for a 28-inch arrow at 280 fps. Default specs: 381 gr arrow, 8.4 mm shaft diameter.
Total arrow mass for a 28" build: 381 gr = 238 gr shaft (8.5 GPI × 28") + 143 gr components (point + insert + nock + fletching).
KE: 66.3 ft·lbf — Momentum: 0.474 slug·ft/s
| Distance | Velocity | KE (ft·lbf) | Momentum (slug) |
|---|---|---|---|
| 0 yd | 280.0 fps | 66.3 ft·lbf | 0.474 |
| 10 yd | 274.8 fps | 63.9 ft·lbf | 0.465 |
| 20 yd | 269.6 fps | 61.5 ft·lbf | 0.456 |
| 30 yd | 264.6 fps | 59.2 ft·lbf | 0.448 |
| 40 yd | 259.7 fps | 57.1 ft·lbf | 0.439 |
| 50 yd | 254.8 fps | 54.9 ft·lbf | 0.431 |
This build pairs a standard-length cut with a modern mid-speed compound launch. At 28 inches the shaft is the mainstream draw-length range, where most factory spine charts are calibrated and tuning is the most forgiving, and 280 fps is the kind of speed produced by mainstream hunting compounds tuned for a balance of speed and forgiveness. Together they finish at about 381 grains, which is what drives the kinetic energy and momentum figures in the table above.
Because this is a standard-length cut, this length sits near the centre of the spine chart, so published reference spines apply most directly. The launch matters too: with a modern mid-speed compound launch, the dynamic-spine reaction is dominated by a versatile setup that flattens trajectory without giving up the stability a moderate arrow weight provides. Pick a static spine that lands stiff once this 28" shaft and your point weight are factored in, then confirm it with bare-shaft or paper tuning.
At roughly 66.3 ft·lbf this is large-game kinetic energy — this is solid large-game energy, covering mule deer, black bear, and wild hog where deeper penetration through heavier bone and muscle is needed. Keep in mind that a standard-length cut at 280 fps is only the starting point; broadhead choice and shot placement still decide the outcome more than the headline energy number.
A modern mid-speed compound launch pushing roughly 381 grains yields about 0.474 slug·ft/s of momentum. That is moderate penetration potential: momentum sits in the moderate range, giving dependable penetration on soft tissue while still favouring shot placement over brute force. Momentum, more than raw kinetic energy, predicts how a 28" arrow holds up against bone and angled entry.
For a standard-length cut launched at 280 fps, dial in rest centre-shot and timing first, then verify broadhead flight against field points at distance. A versatile setup that flattens trajectory without giving up the stability a moderate arrow weight provides — so re-check the tear any time you change point weight, since that shifts the dynamic spine on a 28" shaft more than most archers expect.