5" FPV Drone keeps falling out of the sky

noahmalin

New member
Hey guys,

So, I had a crash a couple of months ago and broke one of my arms. Now, I've waited for two months to finally get the replacement arm and fixed it. But now, when I tried to test fly it, the quad keeps falling out of the sky for no reason. The distance is always different, sometimes 100 m and sometimes very close (in the video its about 5 m). I didn't change any settings in Betaflight, and this quad was flying fine for two years with my settings. The motors don't get hot, and I don't see any physical damage to the drone. Nothing is touching the props. I have the blackbox file attached with my latest test flight dvr video.
Just after the quad disarms, you can see that rxSignalReceived and rxFlightChannelsValid are still 1 and that failsafePhase is still 0. So, the flight controller itself isn't seeing a failsafe condition. It looks like it just disarms for some reason.
Does anyone know what could cause this? Thanks!

https://drive.google.com/drive/folders/1...sp=sharing


5 Inch X Hover Blastr V2
T-Motor F7 Stack - F7 FC, F55A PRO II 3-6S 4-in-1 ESC Combo
DJI Airunit
TBS Crossfire Nano RX, with immortal T antenna
Tango 2
4 x XNOVA 2207 FREESTYLE SMOOTH LINE MOTORS 1700 kv

Tattu R-Line batteries 6s 1800 mAh and 1400 mAh






# version

# Betaflight / STM32F7X2 (S7X2) 4.3.0 Jan 25 2022 / 12:40:47 (2e4f1c922) MSP API: 1.44

# config: manufacturer_id: TMTR, board_name: TMOTORF7, version: c2b8c0d3, date: 2021-06-18T03:42:42Z



# start the command batch

batch start



board_name TMOTORF7

manufacturer_id TMTR



# name: LINK QUALITY



# feature

feature -RX_PARALLEL_PWM

feature RX_SERIAL

feature GPS

feature TELEMETRY



# serial

serial 1 1 115200 57600 0 115200

serial 3 2 115200 57600 0 115200

serial 4 64 115200 57600 0 115200



# beeper

beeper -DISARMING

beeper -ARMING

beeper -ARMING_GPS_FIX

beeper -ARMED



# beacon

beacon RX_LOST

beacon RX_SET



# aux

aux 0 0 0 1700 2100 0 0

aux 1 1 2 1300 1700 0 0

aux 2 2 2 1700 2100 0 0

aux 3 46 3 1700 2100 0 0

aux 4 13 1 1700 2100 0 0

aux 5 35 1 1300 1700 0 0



# master

set acc_calibration = 50,53,86,1

set mag_hardware = NONE

set baro_hardware = NONE

set min_check = 1010

set max_check = 1990

set serialrx_provider = CRSF

set blackbox_sample_rate = 1/8

set blackbox_device = NONE

set dshot_bidir = ON

set motor_pwm_protocol = DSHOT600

set failsafe_procedure = GPS-RESCUE

set yaw_motors_reversed = ON

set small_angle = 180

set gps_provider = UBLOX

set gps_ublox_use_galileo = ON

set gps_set_home_point_once = ON

set gps_rescue_initial_alt = 88

set gps_rescue_descent_dist = 88

set gps_rescue_sanity_checks = RESCUE_SANITY_FS_ONLY

set gps_rescue_min_sats = 6

set gps_rescue_min_dth = 50

set gps_rescue_allow_arming_without_fix = ON

set osd_warn_batt_not_full = OFF

set osd_warn_core_temp = OFF

set osd_warn_rc_smoothing = OFF

set osd_warn_launch_control = OFF

set osd_warn_link_quality = ON

set osd_vbat_pos = 497

set osd_rssi_pos = 417

set osd_link_quality_pos = 2476

set osd_rssi_dbm_pos = 434

set osd_flymode_pos = 2401

set osd_current_pos = 128

set osd_mah_drawn_pos = 2534

set osd_craft_name_pos = 2465

set osd_display_name_pos = 395

set osd_gps_speed_pos = 2057

set osd_gps_lon_pos = 2080

set osd_gps_lat_pos = 2048

set osd_gps_sats_pos = 2433

set osd_home_dir_pos = 2061

set osd_home_dist_pos = 2062

set osd_altitude_pos = 2064

set osd_warnings_pos = 2377

set osd_avg_cell_voltage_pos = 2537

set osd_battery_usage_pos = 490

set debug_mode = GYRO_SCALED

set name = LINK QUALITY

set display_name = Noah Malin



profile 0



# profile 0

set vbat_sag_compensation = 40

set iterm_relax_cutoff = 10

set yaw_lowpass_hz = 70

set throttle_boost_cutoff = 10

set p_pitch = 64

set d_pitch = 54

set p_roll = 59

set d_roll = 50

set p_yaw = 63

set d_min_roll = 0

set d_min_pitch = 0

set feedforward_transition = 40



rateprofile 0



# rateprofile 0

set roll_rc_rate = 15

set pitch_rc_rate = 15

set yaw_rc_rate = 15

set roll_srate = 65

set pitch_srate = 65

set yaw_srate = 65



# end the command batch
batch end
 

Liam B

Well-known member
Looks like it flies quite well from the DVR you provided. At 1:05 in the video, you gave it a pretty good amount of gas and it didn't stutter then like I thought it might. A few things I noticed you didn't mention checking... are the motor screws touching the windings perhaps? I know that's something that could happen after an arm swap. Maybe in the crash, the speed controller was damaged? Do you have another to check this? I know it isn't probably your favorite advice you'll get, but if it's flying well on those PIDs and just being spontaneous in reliability, maybe replace the stack? I doubt the issue would follow
 

noahmalin

New member
First of all, thank you for your help! Unfortunately, that doesn't seem to be the issue. I've checked all my motors, connectors, and wires. I just bought a new FC and ESC; I think that should solve the problem.
 

mastermalpass

Master member
My racing quad started cutting out randomly as well. I eventually discovered it happened when the motors exceeded a certain throttle level when I had the auto-level enabled:


I have yet to properly try the solution as the recommended tip was to re-flash the firmware. Thing is, binding this quad to my Spektrum was a ball-ache and I can't remember how I did it. Didn't manage to get it to bind again when I tried and now I have a FlySky FS-i6x I'm thinking I'll just get one of those receivers for it. When I got my Spektrum DX6i, quadcopters weren't really a thing yet. However, with it plugged into the computer, I can send the throttle up to 100% and that didn't cause it to cut out, so it's not that one of the ESCs is doing an emergency cut-off.
 

Liam B

Well-known member
First of all, thank you for your help! Unfortunately, that doesn't seem to be the issue. I've checked all my motors, connectors, and wires. I just bought a new FC and ESC; I think that should solve the problem.
Yeah as much as it stinks sometimes...: when in doubt, change it out. Especially with the big drones and semi-reliable components, its best to swap before it completely dies above water or at a high altitude.
 

noahmalin

New member
Hey guys, thanks for all the answers!

So, I finally found the solution. The arming switch was twitching; when I opened the modes tab in Betaflight and armed the quad, it was twitching on and off. So, I flashed the FC, and that solved the problem. Hope this helps someone with a similar problem.
 

Liam B

Well-known member
Hey guys, thanks for all the answers!

So, I finally found the solution. The arming switch was twitching; when I opened the modes tab in Betaflight and armed the quad, it was twitching on and off. So, I flashed the FC, and that solved the problem. Hope this helps someone with a similar problem.
That has to be the weirdest issue I've heard... but luckily easily solvable. You're sure it's not the actual radio switch and just the firmware?