Fig. 03 · Cinewhoop · Betaflight 2026.6.2

3-inch cinewhoop

Fly it

Parts: …
Battery: unplugged
Fault: none

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Pick the battery, motors and props. Every number below is recalculated from this craft's own model.

Battery

Motors

Props

Calculated for this build

All-up weight: 441 g
Thrust : weight: 4.3 : 1
Hover throttle: 48%
Max current: 75 A
Hover time: 6.0 min
Hard-flying time: 5.1 min

Checks

Parts match. Smooth and steady enough to film with.

No problems found with this combination.

Cost

Category	Parts	Cost
Electrical	8	$640
Mechanical	5	$72
Total (approx.)	13	$712

A working emulation of the Betaflight command line for this craft: real setting names, real limits and real error messages.

Entering CLI Mode, type 'exit' to return, or 'help'

Up and down recall earlier commands.

Configuration snippets

First setup after flashing after the build

Sets the mixer, the board alignment and the motor protocol: DShot300 with bidirectional telemetry, so each ESC reports rpm. motor_poles is 14 for these 12N14P motors. The O3 is on UART1 with function 131073, MSP (1) plus VTX_MSP (131072), which since Betaflight 4.4 is how a DJI unit gets the OSD; the old displayport_msp_serial is gone. vcd_video_system = HD lays the OSD out on the 53 x 20 HD grid. ExpressLRS is serial RX (64) on UART2 with CRSF.

# Betaflight 2026.6.2, F722 20x20 stack, DJI O3 on UART1, ExpressLRS on UART2
mixer QUADX
set align_board_yaw = 0             # arrow to the nose; 180 if it points back
set motor_pwm_protocol = DSHOT300
set dshot_bidir = ON                # rpm telemetry for the RPM filter
set motor_poles = 14                # 12N14P: count the magnets in the bell
set yaw_motors_reversed = OFF       # props in (ON = props out)
serial UART1 131073 115200 57600 0 115200  # MSP (1) + VTX_MSP (131072): the O3
set osd_displayport_device = MSP
set vcd_video_system = HD
serial UART2 64 115200 57600 0 115200      # 64 = serial RX (ELRS)
set serialrx_provider = CRSF
save

RPM filter: no jello after the build

Small, fast motors shake the gyro, and that shows as jello, a rolling wobble, in the footage. With rpm from every motor, Betaflight puts notch filters exactly on each motor's noise and its harmonics. It needs bidirectional DShot and the right motor_poles; the other numbers are Betaflight's defaults, listed with their ranges.

# RPM filter: notches each motor's noise out of the gyro (no jello in the footage)
set dshot_bidir = ON
set motor_poles = 14
set rpm_filter_harmonics = 3        # 0-3, 0 switches it off
set rpm_filter_min_hz = 100         # 30-200
set rpm_filter_q = 500              # 250-3000
set rpm_filter_fade_range_hz = 50   # 0-1000
set rpm_filter_lpf_hz = 150         # 100-500
save

Switches and failsafe after the build

aux takes the mode's number: 0 ARM, 1 ANGLE, 3 ALTHOLD, 35 FLIP OVER AFTER CRASH (turtle). The channel counts from 0 = AUX1, and the range is in microseconds. There is no ACRO mode to switch on: acro is what flies when angle and altitude hold are off. Failsafe DROP stops the motors after 1.5 s without a link: indoors, near people, falling into the ducts is safer than flying on.

# aux <slot> <mode id> <AUX channel, 0 = AUX1> <start> <end> 0 0
aux 0 0 0 1700 2100 0 0             # ARM on AUX1 high
aux 1 1 1 1300 2100 0 0             # ANGLE on AUX2 mid and high (low = acro)
aux 2 3 2 1700 2100 0 0             # ALTHOLD on AUX3 high (needs a barometer)
aux 3 35 3 1700 2100 0 0            # FLIP OVER AFTER CRASH on AUX4 high
set failsafe_procedure = DROP       # indoors, near people: stop the motors
set failsafe_delay = 15             # 1.5 s of lost link before stage 2
save

Altitude hold for Altitude hold (easy)

Betaflight's ALTHOLD (since 2025.12) holds the height with the flight controller's barometer, so check that your board has one. With ANGLE and ALTHOLD both on, centred throttle holds height; the deadband is the 20 % of stick round the centre that counts as centred, and full stick climbs or sinks at 1.5 m/s (15 tenths). Tilt is capped at 30 degrees.

# Altitude hold: ANGLE (AUX2) + ALTHOLD (AUX3) both on
set alt_hold_deadband = 20          # % of stick around centre that holds height
set alt_hold_climb_rate = 15        # 1.5 m/s at full stick (units of 0.1 m/s)
set angle_limit = 30
save

Cine rates on a switch for Cine (smooth)

Cine is not a Betaflight flight mode but a second rate profile with soft rates: under ACTUAL rates full stick is the larger of rc_rate and srate times 10, so 150 degrees a second on roll and pitch and 100 on yaw. rateprofile counts from 0, so 1 is the Configurator's Rateprofile 2. The adjrange line with function 12 lets a switch on AUX5 pick the profile. More rc smoothing and feedforward smoothing round off the stick moves at the cost of a little delay.

# Cine is a rate profile, not a flight mode: soft rates in profile 2, picked by AUX5
rateprofile 1                       # 0-based: the Configurator's Rateprofile 2
set rates_type = ACTUAL
set roll_rc_rate = 7                # centre sensitivity: 70 deg/s
set roll_srate = 15                 # 150 deg/s at full stick
set pitch_rc_rate = 7
set pitch_srate = 15
set yaw_rc_rate = 7
set yaw_srate = 10                  # 100 deg/s: slow, steady pans
set roll_expo = 0
rateprofile 0
adjrange 0 0 4 900 2100 12 4 0 0    # function 12 = rate profile, chosen by AUX5 (AUX3 is altitude hold)
set rc_smoothing_auto_factor = 60   # 0-250, default 30: smoother sticks, a little delay
set feedforward_smooth_factor = 75  # 0-95, default 65
set angle_limit = 30
save

Angle mode for Angle mode

The flight controller levels the quad when you let go and never tilts it past angle_limit: 30 degrees here instead of the default 60, which keeps the shot steady and the speed down. angle_p_gain is how hard it levels; older Betaflight called it p_level.

# Angle: the sticks set the tilt, centred sticks level it
aux 1 1 1 1300 2100 0 0             # ANGLE on AUX2
set angle_limit = 30                # 10-80 deg, default 60
set angle_p_gain = 50               # 0-200 (was p_level)
save

Soft acro rates for Acro (rate) mode

Acro is what flies with angle and altitude hold off: the sticks set the rotation rate and nothing levels it. 7 and 40 give 70 degrees a second round the centre and 400 at full stick, gentle for a 440 g ducted quad (Betaflight's default is 670). Yaw stops at 270.

# Acro is what flies with ANGLE, HORIZON and ALTHOLD all off (AUX2 low)
set rates_type = ACTUAL
set roll_rc_rate = 7
set roll_srate = 40                 # 400 deg/s at full stick: soft for a heavy whoop
set pitch_rc_rate = 7
set pitch_srate = 40
set yaw_rc_rate = 7
set yaw_srate = 27                  # 270 deg/s
save

Gate timer on the HD OSD for Gate fly-through

osd_tim1 packs the timer's source and precision into one number: 2 (since the last arm) plus 1 x 16 (hundredths) is 18. The position is 2048 (OSD profile 1) plus the column plus 32 per row: column 23, row 1, near the top middle of the HD canvas.

# Gate fly-through timer on the HD OSD: time since arming, in hundredths
set osd_tim1 = 18                   # source 2 (last armed) + precision 1 (hundredths) << 4
set osd_tim_1_pos = 2103            # 2048 (OSD profile 1) + column 23 + row 1 x 32
save

One take through the house for Range: Real-estate tour

Fly the take on the cine profile, with the throttle scaled to 80 % in that profile so a full stick never shoots you through a room. Set the action camera to 4K at 60 frames a second with a shutter of about 1/120 s (twice the frame rate) for natural motion blur, using an ND filter in daylight, and turn on gyro data for stabilising later.

# One take through the house on the cine profile, throttle capped for indoors
rateprofile 1
set throttle_limit_type = SCALE
set throttle_limit_percent = 80     # 25-100: full stick gives 80 %
rateprofile 0
save
# camera: 4K at 60 fps, shutter about 1/120 s (an ND filter outdoors), gyro data on

Check yourself · Bolt on the ducts

1. What are the ducts on a cinewhoop for?
2. A 3-inch prop (76.2 mm) spins inside a duct 79 mm across. Why keep that gap small, but never zero?

Check yourself · Solder the XT60 and the capacitor

1. What does the 470 µF capacitor across the battery pads do?
2. The capacitor went in stripe to plus. What catches that before anything burns?

Check yourself · Mount the O3 air unit

1. Why does this cinewhoop carry two cameras?
2. The goggles show the HD picture but no OSD. What is the most likely cause?
3. On the default build, where does most of the money go?

Check yourself · Fit the props, last

1. Why do the props go on last?
2. Props in, Betaflight numbering: which way does M1, the rear right motor, turn, seen from above?

Check yourself

1. Why does this cinewhoop fly only about 5 to 6 minutes?
2. What is "cine mode" in Betaflight?
3. The link drops while filming inside a house. What does failsafe DROP do?
4. The footage wobbles like jelly. What do you check first?

Meet the cinewhoop

A cinewhoop is a camera platform, not an acrobat. Each 3-inch prop spins inside a duct, a ring that guards it, so the quad can fly through houses, shops and venues, close to people, and survive bumping a wall. This one is a 147 mm true-X carbon frame with a 20 x 20 stack (a 35 A 4-in-1 ESC and an F722 flight controller running Betaflight), a DJI O3 air unit for the HD live view, an ExpressLRS receiver, and a naked action camera on top that records the footage. The ducts, the two cameras and the small props cost flight time: expect 5 to 6 minutes on a 4S 1100. Pick the pack, motors and props and watch the numbers change, build it part by part, run the bench checks with the props off, then fly a smooth take through the house.

Practice task

Fly the yard gate race first, then the real-estate take: in through the front door, down the hallway, out through the sliding door, over the pool, up over the roof and back down to the pad, slowly and smoothly. On a real cinewhoop: turn every prop by hand inside its duct before each flight, check the OSD and link with the props off, test the failsafe, and fly the cine profile with gentle stick moves. Descend slowly or while moving forward, or the quad wobbles in its own prop wash, and land at about 3.5 V a cell.

Build it, run the bench checks, then film a one-take tour of the house

Category

Parts

Cost

Electrical

$640

Mechanical

$72

Total (approx.)

$712

# Betaflight 2026.6.2, F722 20x20 stack, DJI O3 on UART1, ExpressLRS on UART2 mixer QUADX set align_board_yaw = 0 # arrow to the nose; 180 if it points back set motor_pwm_protocol = DSHOT300 set dshot_bidir = ON # rpm telemetry for the RPM filter set motor_poles = 14 # 12N14P: count the magnets in the bell set yaw_motors_reversed = OFF # props in (ON = props out) serial UART1 131073 115200 57600 0 115200 # MSP (1) + VTX_MSP (131072): the O3 set osd_displayport_device = MSP set vcd_video_system = HD serial UART2 64 115200 57600 0 115200 # 64 = serial RX (ELRS) set serialrx_provider = CRSF save

# RPM filter: notches each motor's noise out of the gyro (no jello in the footage) set dshot_bidir = ON set motor_poles = 14 set rpm_filter_harmonics = 3 # 0-3, 0 switches it off set rpm_filter_min_hz = 100 # 30-200 set rpm_filter_q = 500 # 250-3000 set rpm_filter_fade_range_hz = 50 # 0-1000 set rpm_filter_lpf_hz = 150 # 100-500 save

# aux <slot> <mode id> <AUX channel, 0 = AUX1> <start> <end> 0 0 aux 0 0 0 1700 2100 0 0 # ARM on AUX1 high aux 1 1 1 1300 2100 0 0 # ANGLE on AUX2 mid and high (low = acro) aux 2 3 2 1700 2100 0 0 # ALTHOLD on AUX3 high (needs a barometer) aux 3 35 3 1700 2100 0 0 # FLIP OVER AFTER CRASH on AUX4 high set failsafe_procedure = DROP # indoors, near people: stop the motors set failsafe_delay = 15 # 1.5 s of lost link before stage 2 save

# Altitude hold: ANGLE (AUX2) + ALTHOLD (AUX3) both on set alt_hold_deadband = 20 # % of stick around centre that holds height set alt_hold_climb_rate = 15 # 1.5 m/s at full stick (units of 0.1 m/s) set angle_limit = 30 save

# Cine is a rate profile, not a flight mode: soft rates in profile 2, picked by AUX5 rateprofile 1 # 0-based: the Configurator's Rateprofile 2 set rates_type = ACTUAL set roll_rc_rate = 7 # centre sensitivity: 70 deg/s set roll_srate = 15 # 150 deg/s at full stick set pitch_rc_rate = 7 set pitch_srate = 15 set yaw_rc_rate = 7 set yaw_srate = 10 # 100 deg/s: slow, steady pans set roll_expo = 0 rateprofile 0 adjrange 0 0 4 900 2100 12 4 0 0 # function 12 = rate profile, chosen by AUX5 (AUX3 is altitude hold) set rc_smoothing_auto_factor = 60 # 0-250, default 30: smoother sticks, a little delay set feedforward_smooth_factor = 75 # 0-95, default 65 set angle_limit = 30 save

# Angle: the sticks set the tilt, centred sticks level it aux 1 1 1 1300 2100 0 0 # ANGLE on AUX2 set angle_limit = 30 # 10-80 deg, default 60 set angle_p_gain = 50 # 0-200 (was p_level) save

# Acro is what flies with ANGLE, HORIZON and ALTHOLD all off (AUX2 low) set rates_type = ACTUAL set roll_rc_rate = 7 set roll_srate = 40 # 400 deg/s at full stick: soft for a heavy whoop set pitch_rc_rate = 7 set pitch_srate = 40 set yaw_rc_rate = 7 set yaw_srate = 27 # 270 deg/s save

# Gate fly-through timer on the HD OSD: time since arming, in hundredths set osd_tim1 = 18 # source 2 (last armed) + precision 1 (hundredths) << 4 set osd_tim_1_pos = 2103 # 2048 (OSD profile 1) + column 23 + row 1 x 32 save

# One take through the house on the cine profile, throttle capped for indoors rateprofile 1 set throttle_limit_type = SCALE set throttle_limit_percent = 80 # 25-100: full stick gives 80 % rateprofile 0 save # camera: 4K at 60 fps, shutter about 1/120 s (an ND filter outdoors), gyro data on

Meet the cinewhoop

Practice task

Build it, run the bench checks, then film a one-take tour of the house

3-inch cinewhoop

Design it

Calculated for this build

Checks

Cost

Build it

Try a real mistake

Selected part

Parts in the box

Wiring

Safety tests

Smoke stopper test

Motor direction check (props off)

Accelerometer calibration

Prop clearance check (battery out)

Pre-arm check

OSD and link check (props off)

Failsafe test (props off)

Betaflight CLI console

Configuration snippets

First setup after flashing after the build

RPM filter: no jello after the build

Switches and failsafe after the build

Altitude hold for Altitude hold (easy)

Cine rates on a switch for Cine (smooth)

Angle mode for Angle mode

Soft acro rates for Acro (rate) mode

Gate timer on the HD OSD for Gate fly-through

One take through the house for Range: Real-estate tour

Check yourself · Bolt on the ducts

Check yourself · Solder the XT60 and the capacitor

Check yourself · Mount the O3 air unit

Check yourself · Fit the props, last

Check yourself

Meet the cinewhoop

Practice task

3-inch cinewhoop

Design it

Calculated for this build

Checks

Cost

Build it

Try a real mistake

Selected part

Parts in the box

Wiring

Safety tests

Smoke stopper test

Motor direction check (props off)

Accelerometer calibration

Prop clearance check (battery out)

Pre-arm check

OSD and link check (props off)

Failsafe test (props off)

Betaflight CLI console

Configuration snippets

First setup after flashing after the build

RPM filter: no jello after the build

Switches and failsafe after the build

Altitude hold for Altitude hold (easy)

Cine rates on a switch for Cine (smooth)

Angle mode for Angle mode

Soft acro rates for Acro (rate) mode

Gate timer on the HD OSD for Gate fly-through

One take through the house for Range: Real-estate tour

Check yourself · Bolt on the ducts

Check yourself · Solder the XT60 and the capacitor

Check yourself · Mount the O3 air unit

Check yourself · Fit the props, last

Check yourself

Meet the cinewhoop

Practice task