Drone & Rocketry

Possible Causes

• •ESC not calibrated
• •Motor order incorrect in firmware
• •Props on wrong motors
• •Throttle not at zero before arming

Diagnostic Steps

1. 1.Verify throttle stick is at minimum before arming
2. 2.Check Betaflight/ArduPilot motor order matches physical layout
3. 3.Confirm props are on correct motors (CW/CCW)
4. 4.Calibrate ESCs individually or via flight controller
5. 5.Check motor direction in Betaflight motor tab

Possible Causes

• •Power supply noise on video transmitter
• •Ground loop between camera and VTX
• •Insufficient filtering on power leads
• •VTX overheating

Diagnostic Steps

1. 1.Add LC filter on VTX power lead
2. 2.Use shielded video cable between camera and VTX
3. 3.Check VTX is not overheating — ensure airflow over VTX
4. 4.Try different video channel to avoid interference
5. 5.Separate power leads for camera and VTX if possible

Possible Causes

• •Props on wrong motors
• •Motor direction reversed
• •Motor order incorrect
• •Accelerometer not calibrated

Diagnostic Steps

1. 1.Verify prop direction — CW props on CW motors, CCW on CCW motors
2. 2.Check motor direction in Betaflight motor tab with props off
3. 3.Verify motor order in Betaflight matches default layout
4. 4.Calibrate accelerometer with drone on level surface

Possible Causes

• •VTX interference on RC link frequency
• •Low TX power
• •Antenna damaged or disconnected
• •Receiver not bound correctly

Diagnostic Steps

1. 1.Check RC receiver antenna is not near VTX antenna
2. 2.Verify RC link is on correct frequency and not interfering with video
3. 3.Inspect receiver antenna for damage
4. 4.Re-bind receiver to transmitter
5. 5.Check RSSI values in OSD — should be above −90 dBm at operating range

Possible Causes

• •Battery capacity degraded
• •Flying style too aggressive
• •Incorrect battery C rating for application
• •LiPo not fully charged

Diagnostic Steps

1. 1.Check battery internal resistance — above 20 mΩ per cell indicates aging
2. 2.Check voltage sag under load — more than 0.5V per cell sag indicates weak pack
3. 3.Log motor current draw and compare to battery C rating
4. 4.Charge battery fully to 4.2V per cell before flight

Possible Causes

• •Throttle signal not detected
• •Motor disconnected or open phase
• •ESC in calibration mode
• •Battery voltage outside ESC operating range

Diagnostic Steps

1. 1.Verify flight controller is powered and outputting PWM or DSHOT signal to ESC
2. 2.Check motor wire connections at ESC — a single open phase causes continuous beeping on most ESCs
3. 3.If ESC entered calibration mode accidentally, cycle power with throttle at minimum to exit
4. 4.Measure battery voltage — most ESCs beep continuously if voltage is below LVC threshold

Possible Causes

• •Damaged motor winding or bearing
• •ESC timing set incorrectly
• •Partially shorted motor phase
• •Motor bell contact intermittent

Diagnostic Steps

1. 1.Remove props and spin motor by hand — rough or grinding feel indicates bearing damage
2. 2.Listen for uneven tone as motor spins up — a stuttering or grinding sound indicates a damaged winding or partial short
3. 3.Try the motor on a known-good ESC to isolate motor vs. ESC fault
4. 4.Adjust ESC timing in firmware — lower timing can reduce stutter on some motor/ESC combinations

Possible Causes

• •Current draw exceeding ESC rating
• •Insufficient airflow over ESC
• •Motor partially shorted increasing current draw
• •Damaged ESC FETs from a previous overcurrent event

Diagnostic Steps

1. 1.Check ESC current rating against maximum motor current — ESC should be rated at least 20% above peak motor current
2. 2.Verify ESC has adequate airflow — avoid mounting ESC in enclosed areas with no airflow
3. 3.Check motor for partial short — a partially shorted motor draws significantly more current than normal
4. 4.Inspect ESC for burn marks or damaged FETs from a previous crash or overcurrent event

Possible Causes

• •Damaged motor on that arm
• •ESC on that arm faulty
• •Prop damaged reducing apparent RPM
• •Firmware motor output imbalanced

Diagnostic Steps

1. 1.Swap motor to a known-good arm to determine if the fault follows the motor or stays on the arm
2. 2.Check prop on the slow arm for damage — a chipped prop reduces effective pitch and appears as reduced speed
3. 3.If fault stays on the arm after swapping motor, the ESC on that arm is likely faulty
4. 4.Check Betaflight motor output balance — run motor test at a fixed throttle and compare RPM across all four motors

Possible Causes

• •PID gains too high (P term oscillation)
• •Filters not tuned for propeller/frame combination
• •Loose motor or prop causing vibration input
• •Flight controller mounting not vibration-isolated

Diagnostic Steps

1. 1.Reduce P gain on roll and pitch axes by 10–15% and re-test
2. 2.Check all motor screws and prop nuts for tightness — loose hardware causes vibration that confuses the gyro
3. 3.Verify flight controller is mounted on vibration-dampening standoffs, not directly to the frame
4. 4.Enable RPM filtering in Betaflight if using DSHOT and bidirectional telemetry — significantly reduces prop wash oscillation

Possible Causes

• •Wrong COM port selected
• •Flight controller in bootloader mode
• •Driver not installed
• •USB cable data lines damaged

Diagnostic Steps

1. 1.Try a different USB cable — many cables are charge-only with no data lines
2. 2.Check Device Manager (Windows) for the correct COM port — it appears when FC is connected
3. 3.If FC appears as a DFU device, it is in bootloader mode — hold boot button and cycle power to exit
4. 4.Install STM32 USB drivers if the FC is not recognized by Windows

Possible Causes

• •Accelerometer not calibrated
• •Frame not level during calibration
• •ESC not calibrated causing unequal motor speeds
• •Wind — not a fault

Diagnostic Steps

1. 1.Calibrate accelerometer with drone on a known-level surface
2. 2.Verify all four arms are at the same height — a bent frame causes permanent drift that cannot be corrected by calibration alone
3. 3.Calibrate all ESCs simultaneously to ensure equal throttle response
4. 4.Trim can be used for minor corrections in Angle mode but should not be needed in Acro mode

Possible Causes

• •OSD chip not powered
• •UART not configured for OSD
• •Video transmitter and OSD on incompatible standards (NTSC/PAL)
• •Damaged OSD chip from crash or short

Diagnostic Steps

1. 1.Check Betaflight Configurator — verify the correct UART is set to MSP and OSD is enabled in the Configuration tab
2. 2.Verify OSD chip power — most integrated OSD chips draw power from the VTX 5V rail
3. 3.Match video standard — NTSC and PAL must match between camera, OSD, and VTX
4. 4.Inspect FC for physical damage near the OSD chip if drone has been crashed

Possible Causes

• •Antenna obstructed or facing down
• •GPS module not powered
• •Interference from VTX or other electronics
• •Cold start after long storage

Diagnostic Steps

1. 1.Verify GPS antenna faces skyward — patch antennas must point up, helical antennas are omnidirectional
2. 2.Allow 5–10 minutes for cold start fix — subsequent fixes are much faster
3. 3.Move GPS antenna as far from VTX as possible — VTX harmonics can fall near GPS L1 (1575 MHz)
4. 4.Check GPS LED indicator — most modules blink slowly when searching and fast when locked

Possible Causes

• •Insufficient satellite count
• •High HDOP
• •GPS antenna near metal structure causing multipath
• •Magnetic interference on compass

Diagnostic Steps

1. 1.Wait for satellite count above 8 and HDOP below 1.5 before engaging GPS modes
2. 2.Mount GPS antenna on a mast away from the frame to reduce multipath
3. 3.Calibrate compass away from metal structures, vehicles, and power lines
4. 4.Check for compass interference from motors and ESCs — mount GPS/compass module as high as possible on the frame

Possible Causes

• •Home point not set before flight
• •Compass not calibrated
• •GPS lock lost during flight
• •Compass interference causing heading error

Diagnostic Steps

1. 1.Verify home point is set — most flight controllers require GPS lock before arming to set home point
2. 2.Perform compass calibration before each flight in a new location
3. 3.Check telemetry log for GPS satellite count and HDOP during the event
4. 4.Check for heading error on the HUD — if compass reads incorrectly on the ground it will navigate incorrectly in RTH

Possible Causes

• •Battery voltage low
• •Continuity check failing on ejection charges
• •Incorrect switch wiring
• •Firmware not recognizing launch detect threshold

Diagnostic Steps

1. 1.Verify battery voltage meets minimum for altimeter
2. 2.Check ejection charge lead continuity — most altimeters require less than 5Ω
3. 3.Verify arming switch is wired to correct terminals
4. 4.Use altimeter's beep code to diagnose fault — consult manual for code meanings

Possible Causes

• •Single ejection charge failure
• •Apogee or main charge burned but did not ignite propellant
• •Wiring fault on one channel
• •Altitude threshold set incorrectly for main deploy

Diagnostic Steps

1. 1.Verify both channels show continuity before flight
2. 2.Check main deployment altitude setting — must be lower than apogee
3. 3.Inspect ejection charge leads for secure connection to terminals
4. 4.Use backup altimeter for redundancy on high-power flights

Possible Causes

• •Antenna obstructed inside airframe
• •Cold start delay
• •Interference from altimeter or other electronics
• •GPS module not powered

Diagnostic Steps

1. 1.Ensure GPS antenna has view of sky — do not mount inside carbon fiber tube
2. 2.Allow 5–10 minutes for cold start GPS fix before flight
3. 3.Keep GPS away from other electronics
4. 4.Verify GPS is powered and check LED status indicator

Possible Causes

• •Antenna pointing away from ground station at apogee
• •Transmit power insufficient for altitude
• •Frequency interference at launch site
• •Antenna damaged during flight

Diagnostic Steps

1. 1.Use omnidirectional antenna on rocket and ground station for tumbling flight
2. 2.Increase transmit power within legal limits
3. 3.Monitor frequency for interference before launch
4. 4.Review telemetry log for last received altitude to determine where link was lost