Video summary

How to build a 7-inch long range FPV Drone for $150

Main summary

Key takeaways

Technology

Summary (technological concepts / build + configuration highlights)

Goal & cost strategy (2024)

  • Build a 7-inch long-range FPV drone under $150 by using low-cost mass-produced motors.
  • The video claims that because manufacturing has shifted globally, 7-inch motors (e.g., 2807 size) can be bought in sets for <$35 shipped, rather than paying ~$30+ each from brand-name suppliers.
  • A teaser mentions potentially using larger 3115 motors for 10-inch props with even cheaper bulk pricing (future build idea).

Frame

  • Uses a Mark 47 “in version” clone frame from AliExpress (~$15).
  • Recommends verifying the correct frame variant that includes 3D-printed/injection-molded mounting accessories for:
    • GoPro mounting
    • Motor protection

Flight stack

  • Generic F4 “v3” deck with an ESC included (45A mentioned).
  • Mentions an alternative 60A version (referencing prior guidance).
  • Notes that many stacks come under different brand names but are essentially identical (same factory/schematics).
  • Claims the combined stack can be found for under ~$40.

Receiver (ExpressLRS / ELRS)

  • Uses ExpressLRS with a HappyModel EP1 micro receiver.
  • Caution: the receiver bag reportedly doesn’t include wiring harness/silicone leads, only antennas.
    • If you need those wires, the video suggests an alternative such as a JMcu micro ELRS receiver that includes leads.

Video (analog budget)

  • VTX: Rush Tank Solo VTX (~1W, under ~$35), aluminum case.
  • Antenna:
    • Stock whip is described as not great.
    • Upgrade suggested: Rush RHCP SMA antenna (~$5 on AliExpress).
  • Camera: RunCam Phoenix 2 SE, chosen for performance and low cost (< $15 availability).

Build procedure and troubleshooting approach (tutorial structure)

  1. Dry fit planning (no soldering yet)

    • Assemble the frame first and do a dry fit of components to avoid rework.
    • Verify that the mounting accessory versions are correct.
    • Catch hardware mismatches early (example issue): motor mounting screws/bolts are too short → plan to use longer M3 bolts.

  2. Pre-solder electronics verification (Betaflight)

    • Connect the flight controller to Betaflight Configurator to confirm it’s working before soldering.
    • Check firmware version (example shows older 4.4.2) and update to latest 4.5.1 via Betaflight’s firmware upgrade flow.
    • If flashing fails due to DFU mode:
      • Enter bootloader/DFU mode using the configurator (“activate bootloader DFU”).
    • After flashing: do an accelerometer calibration sanity check.

  3. Mounting flight controller and ESC

    • Use rubber dampers (“rubber gummies”).
    • Use M3 bolts because included hardware is insufficient.

  4. Motor wiring length planning

    • Mount one motor temporarily, measure required lead length, then only afterward commit to wiring.

  5. Video transmitter + camera mounting

    • VTX has 20x20 mounting holes, mounts using M2 screws.
    • Uses the frame accessory kit for antenna mount/adaptor.
    • Camera front mount uses M2 screws.

  6. Soldering considerations

    • Battery leads to the 4-in-1 ESC are described as the hardest solder due to the ESC ground plane sinking heat.
    • Recommends temperature-controlled irons (example: Pinel / TS100) with fast-reacting temperature sensing.

  7. Short protection + ESC firmware

    • Use a smoke stopper to limit current into the ESC if a short occurs.
    • Notes potential ESC firmware updates (conceptually similar to BLHeli / “run blue J” ideas), while powered and accessible.

  8. Motor-to-ESC connections (optional connectors)

    • Instead of soldering motors directly, uses MT30 connectors for easier swapping across builds.
    • Still emphasizes correct connection/testing of motor wiring.

  9. Accessory wiring (VTX + control UART + camera)

    • Wiring includes flight controller/Betaflight connections for:
      • VTX: ground, power, video signal, plus UART control for VTX parameter switching.
      • Camera: ground, 5V, and video only.
    • Recommends a smaller solder tip for tiny flight-controller pads.

  10. Receiver binding workflow (ExpressLRS)

    • Suggests a RadioMaster Pocket ELRS transmitter (claimed $60).
    • Binding is described as the most frustrating ELRS part due to multiple possible methods.
    • Suggests the binding phrase method:
      • Use receiver Wi‑Fi configurator flow to retrieve binding phrase (example: open configurator after leaving receiver plugged in ~1 minute).

  11. First flight as a sanity test

    • Flight described as relaxed cruising with GoPro + analog DVR overlay.
    • Issue found: OSD current readings are incorrect because the current sensor on the flight controller is broken (voltage values appear correct).
    • Overall handling is described as smooth/floatier for a 7-inch vs a 5-inch freestyle drone.

Key performance/analysis notes from the flight

Handling difference (7” vs 5” styling)

  • The 7-inch uses larger props and less disc-loading than typical 5-inch freestyle setups.
  • Result: a more floaty, relaxed “long-range/plane-like” feel.

Battery/flight time claims

  • Example run: 4S ~1800 mAh (estimate) with about ~7 minutes on that pack.
  • Mentions achieving >20 minutes of hovering using larger 4S packs (e.g., 4S 2P 3000 or 4S 2P 5000 mAh Li-ion).

Missing long-range safety feature

  • Explicitly notes the build currently lacks a GPS module.
  • Planned future work:
    • Add GPS
    • Set up GPS rescue / RTH confidence
    • Do longer-distance flights (example: ~1 mile scenarios)

Betaflight “final configuration” workflow (detailed tutorial sequence)

  1. Setup prep

    • Props off
    • Use a USB fan aimed at the flight controller/VTX while powered (not flying).

  2. Receiver & ports

    • Configure serial RX (ELRS) on UART1.
    • Verify in receiver tab that roll/pitch/yaw/throttle respond properly.
    • Confirm receiver provider as CRSF (ExpressLRS via Crossfire-like naming).

  3. Board/sensor alignment

    • Check orientation by moving the quad and ensuring Betaflight graphical model matches.
    • If misaligned: adjust in Board and Sensor Alignment.

  4. Flight modes

    • ExpressLRS arming/disarming logic:
      • ARM on AUX1 with value 2000
      • DISARM on 1000
    • Sets:
      • Acro mode around 1500
      • Angle (staple) mode on AUX2 around 2000 (naming varies in subtitles)

  5. Motors: order + direction

    • Use Betaflight motor wizards to:
      • Validate all four motors spin
      • Run Motor Output Reorder Wizard
      • Run Motor Direction Wizard
    • Example outcome: some motors initially reversed; corrected via motor direction wizard.
    • Emphasizes: correctness is configuration/software—direction can be swapped without re-soldering.

  6. VTX/OSD integration (the finicky part)

    • VTX connected to UART3; configured via SmartAudio 2.1 (or similar).
    • Load a VTX table JSON from the manufacturer website for the specific:
      • Rush Tank Solo SmartAudio 2.1
      • 48-channel version
    • Use VTX LED feedback to confirm power levels:
      • 25mW = green
      • 400mW = yellow
      • 800mW = red
      • max purple
    • Desired runtime defaults:
      • CH band + channel 6
      • Runtime power set to 400mW
      • Enable low power disarm so VTX powers down until the quad is armed (still uses LED feedback while disarmed)
    • OSD setup:
      • Ensure analog (NTSC) mode, avoiding accidental selection of an unrelated HD mode.
      • Reposition/select key OSD elements:
        • timers (on time / flight time)
        • battery cell voltage / voltage metrics
        • craft name
        • VTX band/channel info
        • throttle position / artificial horizon
      • Notes: OSD elements may require save + reboot to reliably appear on the monitor.

Main speakers / sources

  • Primary speaker: The video’s author/instructor (not named in the subtitles).
  • Referenced external source: Joshua Bardwell (recommended for Betaflight/ELRS binding and firmware resources).

Mentioned brands/products

  • Betaflight Configurator
  • ExpressLRS (ELRS)
  • RadioMaster Pocket
  • Rush Tank (VTX/camera/antennas)
  • RunCam Phoenix 2 SE
  • Smoke stopper
  • Pinel / TS100 soldering irons

Original video