COMPONENT
ARCHITECTURE

Five Core Systems — Drone Component

A drone is simpler than it looks. Five systems, each with a clear job. If you understand what each one does and how they connect, you can build, troubleshoot, and field-repair any FPV (First Person View) drone.

How They Connect

Power flows from battery to everything. The ESC (Electronic Speed Controller) takes battery power and feeds it to the four motors — each motor independently, at different speeds, which is how the drone tilts and turns. The flight controller (FC) is the brain. It reads the gyroscope and accelerometer 400 times per second, calculates how fast each motor should spin, and tells the ESC. The radio receiver (RX) receives the pilot's stick commands from the handheld controller and passes them to the FC. The FPV camera captures video and sends it to the video transmitter (VTX), which broadcasts to the pilot's goggles on a separate frequency (5.8 GHz, separate from the control link on 300 MHz (mil-band)).

Important: the video link (5.8 GHz) and the control link (300 MHz (mil-band) ELRS) are completely separate systems on different frequencies. If one fails, the other continues working. You can lose video but still have control (fly blind by instruments/telemetry), or lose control but still see video (the drone executes its failsafe — return to launch or land).

Frame Selection — Carbon Fiber vs Injection Molded

FPV frames divide into two categories: carbon fiber plate construction (cut from sheets, assembled with standoffs) and injection-molded unibody (single-piece plastic or composite). Carbon fiber offers superior stiffness-to-weight ratio (Young's modulus 230 GPa vs 3 GPa for polycarbonate) and vibration damping — critical for clean IMU data that EKF3 depends on for navigation. The tradeoff: carbon fiber is electrically conductive, which can interfere with antenna placement, and cracks catastrophically on impact rather than flexing.

For tactical FPV at €270 per unit, the frame is expendable. A 5-inch carbon frame (iFlight Chimera, Diatone Roma) costs €25-40 and weighs 100-130g. Swedish supplier: Electrokit.com (Malmö) stocks several options. For arctic operations, carbon fiber maintains its mechanical properties to -50°C while polycarbonate becomes brittle below -10°C — carbon is the only viable frame material for winter operations above the Arctic Circle. Oxeon AB in Borås manufactures spread-tow carbon fiber fabric that could supply a domestic frame production capability.

Motor and ESC Pairing

The motor-ESC combination determines thrust, efficiency, and response characteristics. Emax ECO II 2207 2400KV (€8) produces 1.2 kg thrust on 6S with 5-inch propellers — thrust-to-weight ratio of 8:1 at the typical 600g FPV all-up weight. This ratio provides aggressive maneuverability needed for terminal attack dives and evasive maneuvering. ESC must support DShot600 protocol for digital motor control — SpeedyBee BLS 55A (€25 for 4-in-1 stack) handles 55A continuous per motor with 48 kHz PWM switching frequency.

KV rating determines the tradeoff between speed and efficiency. Higher KV (2400+) spins faster for more aggressive flight but draws more current and reduces flight time. Lower KV (1700-2000) is more efficient for cruising but lacks the snap response needed for terminal FPV attack. The 2400KV choice prioritizes combat performance over endurance — a tactical FPV mission is 5-15 minutes, well within the 6S 1300mAh battery capacity at aggressive throttle. Fischer 26 uses T-Motor U8 at much lower KV (100) for efficient fixed-wing cruise over 2+ hours.

Related Chapters

External source: Obemannat luftfartyg – Wikipedia

Implementation

# FPV Drone Wiring — Pin Assignment
WIRING = {
    "battery": "XT60 → ESC power input (6S, 22.2V)",
    "esc_to_motors": {
        "M1": "ESC pad 1 → Motor FR (front-right)",
        "M2": "ESC pad 2 → Motor RL (rear-left)",
        "M3": "ESC pad 3 → Motor FL (front-left)",
        "M4": "ESC pad 4 → Motor RR (rear-right)",
        "protocol": "DShot600"
    },
    "fc_uart": {
        "UART1_TX/RX": "MANET radio (MAVLink 2.0, 115200 baud)",
        "UART2_TX/RX": "Jetson companion (MAVLink, 921600 baud)",
        "UART6_TX/RX": "GPS (if used) or telemetry"
    },
    "power_regulation": {
        "BEC1 (5V 3A)": "Flight controller + FPV camera + VTX",
        "BEC2 (5V 5A)": "Jetson Orin Nano ONLY (separate!)",
        "WARNING": "NEVER share BEC between FC and Jetson — brownout kills drone"
    }
}

Swedish Supply Chain

Sources

ArduPilot hardware documentation (ardupilot.org). SpeedyBee F405 V4 pinout diagram. ExpressLRS documentation (expresslrs.org). Oscar Liang component guides (oscarliang.com, 2024).