Painless360's latest in-depth review tackles the AtomRC Penguin, a uniquely-designed fixed wing drone that promises versatility for FPV use. Read on for a full rundown of his thorough testing and final verdict.
TL:DR - The Good and Bad
- Twin motors provide tons of thrust for aggressive climbs and easy hand launches
- Wide speed range from 10 mph up to over 70 mph
- Efficient cruise at lower throttle settings allows long flight times
- Durable foam construction has held up well so far
- Capable of basic aerobatic maneuvers like loops and rolls
- Very quiet thanks to 6-inch props
- Protected nose section fits FPV gear nicely
- Large internal capacity for big batteries up to 4200mAh
- Flight controller mounted far back from CG point
- Pre-set throws are much too high
- Does not excel at very high speeds over 90mph
- Airframe remains bulky when broken down for transport
- Nose durability uncertain long-term
- Shovels grass and dirt into nose openings during landings
Straightforward Build with Room for Improvement
Construction of the Penguin took just a couple hours, with no major issues. Painless360 opted for ExpressLRS over SBUS to avoid telemetry problems with the flight controller. Upgrading the firmware to iNav 6.1 enabled key fixes like improved AHRS. He also tuned settings like AHRS type and arming to better suit the plane.
While the spacious airframe easily fits large batteries or HD FPV gear, its rear-mounted flight controller could be positioned further forward. This would enhance balance by placing it nearer the CG and also allow more room in the back for components. Painless360 found the extreme pre-set throws made the plane too twitchy.
Impressive Speed Range with Twin Electric Power
The Penguin's twin motors generate substantial static thrust for rocket-like climbs and effortless hand launching. At just 1/3 throttle, it cruises efficiently at 30mph and 3.5A draw. This makes slower, longer flights possible. At 50% throttle, it zips along at 46mph and 8A. Top speeds exceed 70mph at full throttle.
Despite its odd shape, the Penguin tracks well and feels stable in the air. With lowered throws, the roll and pitch response feels crisp but not too sensitive. It can easily perform aerobatic loops and rolls thanks to the ample thrust and control authority. The 6-inch props keep noise pleasantly low.
Durable Airframe with Some Minor Shortcomings
Though the foam construction has proven durable so far, more flight time will reveal how well the nose holds up. The Penguin excels at most tasks but won't break any speed records. Transport and storage is mediocre since the airframe remains bulky when broken down.
On the plus side, the wings can be removed without disconnecting servo links. FPV equipment fits nicely within the protected nose section. Landings are gentle thanks to its glide capabilities and low stall speed. The ample interior space allows large batteries up to 4200mAh for long flight times.
Verdict: A Versatile FPV Performer
Despite a few small areas for improvement, the AtomRC Penguin shines as a versatile all-purpose FPV plane. With excellent efficiency, a wide speed envelope and aerobatic abilities, it makes a great platform for casual and aggressive flying alike. For these reasons, Painless360 gives it his official seal of approval.
AtomRC Penguin Inav Diff
Here is the Diff file provided by Painless360 that he used on his build, please only use this with the exact same version of Inav, otherwise use this as a guide to get your settings optimally configured.
# version # INAV/ATOMRCF405NAVI 6.1.1 Jun 13 2023 / 10:02:51 (42ced253) # GCC-10.2.1 20201103 (release) # WARNING - USE WITH CAUTION, NO MODES OR OSD LAYOUT IN THIS FILE # ALSO - BE AWARE THAT AUTOLAUNCH IS ON ALL THE TIME AND THE PROPS ARE SET TO SPIN ON THROTTLE UP # Mixer: motor mixer mmix reset mmix 0 1.000 0.000 0.000 0.000 mmix 1 1.000 0.000 0.000 0.000 # Mixer: servo mixer smix reset smix 0 1 0 80 0 -1 smix 1 2 0 80 0 -1 smix 2 3 1 80 0 -1 # Outputs [servo] servo 1 1000 2000 1539 -100 servo 2 1000 2000 1479 -100 servo 3 1000 2000 1426 100 servo 4 1000 2000 1500 -100 servo 6 1000 2000 1500 -100 # safehome # features feature MOTOR_STOP feature GPS feature PWM_OUTPUT_ENABLE feature FW_LAUNCH feature FW_AUTOTRIM # beeper # blackbox blackbox -NAV_ACC blackbox NAV_POS blackbox NAV_PID blackbox MAG blackbox ACC blackbox ATTI blackbox RC_DATA blackbox RC_COMMAND blackbox MOTORS blackbox -GYRO_RAW blackbox -PEAKS_R blackbox -PEAKS_P blackbox -PEAKS_Y # Receiver: Channel map map AETR # Ports serial 0 0 115200 115200 0 115200 serial 3 2 115200 115200 0 115200 serial 4 33554432 115200 115200 0 115200 # LEDs # LED color # LED mode_color # Modes [aux] # Adjustments [adjrange] # Receiver rxrange # temp_sensor # Mission Control Waypoints [wp] #wp 0 invalid # OSD [osd_layout] # Programming: logic # Programming: global variables # Programming: PID controllers # master set gyro_main_lpf_hz = 25 set dynamic_gyro_notch_q = 250 set dynamic_gyro_notch_min_hz = 30 set gyro_zero_y = -2 set ins_gravity_cmss = 997.973 set acc_hardware = BMI270 set acczero_x = -15 set acczero_y = 8 set acczero_z = -11 set accgain_x = 4098 set accgain_y = 4086 set accgain_z = 4100 set align_mag = CW270FLIP set mag_hardware = NONE set baro_hardware = SPL06 set motor_pwm_protocol = DSHOT600 set failsafe_procedure = RTH set align_board_yaw = 1800 set platform_type = AIRPLANE set has_flaps = ON set model_preview_type = 14 set servo_pwm_rate = 100 set small_angle = 180 set ahrs_inertia_comp_method = ADAPTIVE set applied_defaults = 3 set gps_sbas_mode = AUTO set gps_ublox_use_galileo = ON set airmode_type = STICK_CENTER_ONCE set nav_extra_arming_safety = ON set nav_wp_radius = 5000 set nav_wp_max_safe_distance = 500 set nav_rth_allow_landing = NEVER set nav_rth_altitude = 7000 set nav_fw_control_smoothness = 2 set nav_fw_launch_velocity = 150 set nav_fw_launch_accel = 1500 set nav_fw_launch_max_angle = 180 set nav_fw_launch_motor_delay = 100 set nav_fw_launch_timeout = 10000 set nav_fw_launch_max_altitude = 5000 set nav_fw_launch_climb_angle = 25 set osd_video_system = AVATAR set osd_units = IMPERIAL set osd_time_alarm = 20 set osd_alt_alarm = 110 set osd_home_position_arm_screen = OFF set osd_switch_indicators_align_left = OFF # profile profile 1 set fw_p_pitch = 15 set fw_i_pitch = 5 set fw_d_pitch = 5 set fw_ff_pitch = 80 set fw_p_roll = 15 set fw_i_roll = 3 set fw_d_roll = 7 set fw_p_yaw = 50 set fw_i_yaw = 0 set fw_d_yaw = 20 set fw_ff_yaw = 255 set max_angle_inclination_rll = 450 set dterm_lpf_hz = 10 set fw_turn_assist_pitch_gain = 0.400 set nav_fw_pos_z_p = 25 set nav_fw_pos_z_d = 8 set nav_fw_pos_xy_p = 55 set d_boost_min = 1.000 set d_boost_max = 1.000 set rc_expo = 30 set rc_yaw_expo = 30 set roll_rate = 18 set pitch_rate = 9 set yaw_rate = 3 # profile profile 2 set fw_p_pitch = 15 set fw_i_pitch = 5 set fw_d_pitch = 5 set fw_ff_pitch = 96 set fw_p_roll = 15 set fw_i_roll = 3 set fw_d_roll = 7 set fw_ff_roll = 40 set fw_p_yaw = 50 set fw_i_yaw = 0 set fw_d_yaw = 20 set fw_ff_yaw = 255 set max_angle_inclination_rll = 600 set max_angle_inclination_pit = 600 set dterm_lpf_hz = 10 set fw_turn_assist_pitch_gain = 0.400 set nav_fw_pos_z_p = 25 set nav_fw_pos_z_d = 8 set nav_fw_pos_xy_p = 55 set d_boost_min = 1.000 set d_boost_max = 1.000 set fw_level_pitch_trim = 2.000 set rc_expo = 30 set rc_yaw_expo = 30 set roll_rate = 31 set pitch_rate = 13 set yaw_rate = 3 # profile profile 3 set fw_p_pitch = 15 set fw_i_pitch = 5 set fw_d_pitch = 5 set fw_ff_pitch = 80 set fw_p_roll = 15 set fw_i_roll = 3 set fw_d_roll = 7 set fw_p_yaw = 50 set fw_i_yaw = 0 set fw_d_yaw = 20 set fw_ff_yaw = 255 set max_angle_inclination_rll = 450 set dterm_lpf_hz = 10 set fw_turn_assist_pitch_gain = 0.400 set nav_fw_pos_z_p = 25 set nav_fw_pos_z_d = 8 set nav_fw_pos_xy_p = 55 set d_boost_min = 1.000 set d_boost_max = 1.000 set rc_expo = 30 set rc_yaw_expo = 30 set roll_rate = 18 set pitch_rate = 9 set yaw_rate = 3 # battery_profile battery_profile 1 # battery_profile battery_profile 2 # battery_profile battery_profile 3