Sparrow Expeditions · The Forge
Build the arrow. Tune the bow. Read the math.
A bowhunter's workshop calibrated against documented hunts. The first 3D wind-drift visualizer in the category. The only spine recommender that models extended-length inserts. Field-anchored math, not pulled from a spec sheet.
The Forge · every tool
One workshop. Eight surfaces. Always in sync.
Save your gear once. Tune, log, review, optimize across every surface. All math runs on the same calibration anchors.
My Bows →
Save your bow specs once. Auto-loads into every other tool. Primary bow flag for the one you reach for first.
FreeMy Arrows →
Build profiles per shaft + components. Active arrow flag drives the visualizer, the review, the spine ladder.
Hunter+Tune Wizard →
The full pro-shop tune in a guided sequence — pre-flight, cam timing, tiller, paper, bareshaft, broadhead. 100+ bow specs verified.
Hunter+Range Log →
Log every practice. Track PBs and streaks. Auto-diagnose your group pattern with a specific tuning fix deep-linked into the Wizard.
FreeBuild Review →
Full read-out on your active arrow: warnings, balance, FOC, spine ladder, stability, trajectory, weight breakdown. Share the URL.
ProWind-Drift Visualizer →
Compare two builds in 3D under your wind, altitude, range. Forge Score updates live. Measure your tune from a bareshaft offset or group photo.
Hunter+Spine What-If →
The only spine calculator that models extended-length inserts (Firenock CTI, Iron Will Snyder Core, Evolution glue-in, Easton DG).
FreeMethods & math →
The full methodology behind the Forge Score, the trajectory model, the spine math, the Ashby penetration coefficients. Read it, argue with it.
Why this is different.
Three claims that separate Sparrow Forge from every other calculator on the internet, each one tied to a documented hunt or peer-published method.
Field-anchored math
The Forge Score, the yaw→drift coupling, and the broadhead-by-game-class matrix are all calibrated against documented hunts — eland, wildebeest, red stag — not generic spec sheets.
Methods §12–13 · Field NotesThe only extended-insert spine model
Stu Miller’s calculator handles HIT depth. We extend the math to model Firenock CTI 3"/6", Iron Will Snyder Core, Evolution glue-in, and Easton DG — anchored on Ethics Archery’s measured stiffening curve.
/pages/spine-what-if3D wind-drift visualizer, first in category
Compare two builds in a real 3D scene under your wind, altitude, and shot scenario. See the trajectory walk, the apex marker, the brush clearance. No competitor ships this.
/pages/wind-driftField Notes · calibration anchors
The hunts the math is built on.
Each hunt is one calibration anchor. Read them in any order.
Eland · Ashby reframe
500-Grain Eland — What Ashby Missed
The almost-pass that anchors the broadhead-type × game-class matrix. Why a 500gr mech can fail on the largest African game even with the right FOC.
Read →Wildebeest · Tune-quality canary
Three Feet at Sixty Yards
The wildebeest hunt that anchors the yaw→drift coupling. Bareshaft drift at hunting distance is the cheapest tune-quality canary that exists.
Read →Red stag · Shot scenario × head matrix
Thirty-Five Down a Canyon
Quartering away, downhill, through both shoulders. The math said the shot was inside the envelope before I took it.
Read →Free forever. Paid tiers add the loop.
Save bows + arrows on Free. Hunter ($6/mo) adds the Tuning Wizard, Range Log auto-diagnose, and the Compete module. Pro ($12/mo) adds the precision Sight Tape printer, Shot Solver, and A/B build comparison. Annual saves 2 months on every paid tier.