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DragTree

NHRA Pro Tree reaction timer — accelerometer launch detection, no internet
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.
  • app screenshot

Versions

Although APK downloads are available below to give you the choice, you should be aware that by installing that way you will not receive update notifications and it's a less secure way to download. We recommend that you install the F-Droid client and use that.

Download F-Droid
  • Version 1.7.3 (164) suggested Added on Sep 29, 2026

    x86_64

    This version requires Android 7.0 or newer.

    It is built and signed by the original developer, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • access sensor data at a high sampling rate
      Allows the app to sample sensor data at a rate greater than 200 Hz
    • change your audio settings
      Allows the app to modify global audio settings such as volume and which speaker is used for output.
    • control vibration
      Allows the app to control the vibrator.
    • com.flyboybyte.dragtree.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 32 MiB PGP Signature | Build Log

  • Version 1.7.3 (163) - Added on Sep 29, 2026

    x86

    This version requires Android 7.0 or newer.

    It is built and signed by the original developer, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • access sensor data at a high sampling rate
      Allows the app to sample sensor data at a rate greater than 200 Hz
    • change your audio settings
      Allows the app to modify global audio settings such as volume and which speaker is used for output.
    • control vibration
      Allows the app to control the vibrator.
    • com.flyboybyte.dragtree.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 32 MiB PGP Signature | Build Log

  • Version 1.7.3 (162) - Added on Sep 29, 2026

    arm64-v8a

    This version requires Android 7.0 or newer.

    It is built and signed by the original developer, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • access sensor data at a high sampling rate
      Allows the app to sample sensor data at a rate greater than 200 Hz
    • change your audio settings
      Allows the app to modify global audio settings such as volume and which speaker is used for output.
    • control vibration
      Allows the app to control the vibrator.
    • com.flyboybyte.dragtree.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 31 MiB PGP Signature | Build Log

  • Version 1.7.3 (161) - Added on Sep 29, 2026

    armeabi-v7a

    This version requires Android 7.0 or newer.

    It is built and signed by the original developer, and guaranteed to correspond to this source tarball.

    Permissions
    • view network connections
      Allows the app to view information about network connections such as which networks exist and are connected.
    • access sensor data at a high sampling rate
      Allows the app to sample sensor data at a rate greater than 200 Hz
    • change your audio settings
      Allows the app to modify global audio settings such as volume and which speaker is used for output.
    • control vibration
      Allows the app to control the vibrator.
    • com.flyboybyte.dragtree.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 27 MiB PGP Signature | Build Log

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