DragTree
DragTree simulates a real NHRA Christmas Tree (drag strip starting lights) and uses your phone's accelerometer to measure reaction time to the millisecond — no tapping required.
Mount your phone on the dash, stage up, watch the tree, and floor it. The app detects launch G-force automatically and records your RT. Fully offline — no internet, no account, no ads.
TREE MODES
• Pro Tree (.400s) — all three ambers fire simultaneously, green follows 0.400s later
• Sportsman Tree (.500s) — ambers count down one at a time, green follows 0.500s after the last amber
REACTION GRADING
• Perfect: 0–0.049s
• Pro: 0.050–0.099s
• Great: 0.100–0.199s
• Good: 0.200–0.349s
• Late: over 0.349s
• Red Light: launched before green
FEATURES
• Accelerometer launch detection — rolling baseline, no calibration step
• Three sensitivity presets: Gentle (0.15g), Normal (0.25g), Hard (0.46g) plus custom dial
• Session history — last 30 runs, personal best highlighted
• Reaction time trend chart — bar chart of recent runs
• Series mode — run 3, 5, or 10 back-to-back stages with avg RT, best/worst, and consistency score
• Optional audio cues — amber click, green chirp, result ping, red-light buzz
• Diagnostics screen — live G-force, sensor telemetry, last-launch breakdown
• Browser / simulator mode — on-screen FLOOR IT button for desktop practice
PERMISSIONS
• HIGH_SAMPLING_RATE_SENSORS — required for 125 Hz accelerometer sampling. No other sensor or location permissions used.
No internet connection required after install.
Mount your phone on the dash, stage up, watch the tree, and floor it. The app detects launch G-force automatically and records your RT. Fully offline — no internet, no account, no ads.
TREE MODES
• Pro Tree (.400s) — all three ambers fire simultaneously, green follows 0.400s later
• Sportsman Tree (.500s) — ambers count down one at a time, green follows 0.500s after the last amber
REACTION GRADING
• Perfect: 0–0.049s
• Pro: 0.050–0.099s
• Great: 0.100–0.199s
• Good: 0.200–0.349s
• Late: over 0.349s
• Red Light: launched before green
FEATURES
• Accelerometer launch detection — rolling baseline, no calibration step
• Three sensitivity presets: Gentle (0.15g), Normal (0.25g), Hard (0.46g) plus custom dial
• Session history — last 30 runs, personal best highlighted
• Reaction time trend chart — bar chart of recent runs
• Series mode — run 3, 5, or 10 back-to-back stages with avg RT, best/worst, and consistency score
• Optional audio cues — amber click, green chirp, result ping, red-light buzz
• Diagnostics screen — live G-force, sensor telemetry, last-launch breakdown
• Browser / simulator mode — on-screen FLOOR IT button for desktop practice
PERMISSIONS
• HIGH_SAMPLING_RATE_SENSORS — required for 125 Hz accelerometer sampling. No other sensor or location permissions used.
No internet connection required after install.
