Alfa Monster 7-inch FPV drone
It is not a secret that I am a huge fan of 7-inch FPV quadcopters. To be honest, most of my drones are the ones with 7-inch propellers. Why? There are a few reasons: they are more efficient than 5", can be used for cruising, freestyle and long-range. And they climb... oh boy, they can climb!
What's the most important in 7-inch quadcopter drones? Thick arms and big motors. Forget about 4mm arms and the motors we use on 5" quads only with lower KV. It does not work like that. 6mm arms in absolute minimum - we need stiff arms that are not resonating in flight. Motor size 2208 is the minimum (you might try with 2207 but it might not work the best) but the fun begins with 2506 and peaks at 2507!
Like my Alfa Monster with 7-inch arms and Brotherhobby Avenger V2 2507 1750KV motors on 4S. A shitload of torque, power and climb rate! Full specification:
- Motors: iFlight XING 2806.5 1800KV
- Frame: Alfa Monster 7 inch
- Props: HQProp 7x4x3
- ESC: Holybro Tekko32
- Flight controller: Matek F722-SE running INAV
- FPV camera: Foxeer T-Rex
- VTX: AKK X2 Ultimate
- 5.8 GHz antenna: Foxeer Lollipop
- RX: FrSky R9MM-OTA
Bear in mind, Alfa Monster is not a perfect frame. Arms could be slightly more durable and wider and mounting holes are too close to the edges. On top of that, the space inside is rather limited. That's due to the "racing" origins of this frame. And on top of that, mount for an HD camera like GoPro has to be improvised as there is no "factory provided" way to do it.
- Low weight and low moment of inertia gives a great flight performance
- Frame resonant frequency is high enough that it is not vibrating in flight
- Arms are not strong enough and they tend to break after some beating. It's a good idea to have one or two spares
- Space inside is very limited and some creativity to fit everything you need is needed
- There is not a good place to fit a GoPro by default. You have to improvise
INAV Reference Tune
INAV 2.6 Alfa2 can be downloaded from here
# mixer mmix reset mmix 0 1.000 -1.000 1.000 -1.000 mmix 1 1.000 -1.000 -1.000 1.000 mmix 2 1.000 1.000 1.000 1.000 mmix 3 1.000 1.000 -1.000 -1.000 # feature feature PWM_OUTPUT_ENABLE # master set looptime = 250 set gyro_hardware_lpf = 256HZ set gyro_lpf_hz = 90 set gyro_lpf_type = PT1 set dynamic_gyro_notch_enabled = ON set dynamic_gyro_notch_q = 200 set dynamic_gyro_notch_min_hz = 75 set gyro_kalman_enabled = ON set gyro_kalman_q = 200 set gyro_kalman_w = 8 set blackbox_rate_denom = 4 set motor_pwm_rate = 8000 set motor_pwm_protocol = DSHOT300 set throttle_idle = 13.000 set model_preview_type = 3 set small_angle = 180 set applied_defaults = 2 set mc_airmode_type = THROTTLE_THRESHOLD set i2c_speed = 800KHZ # profile profile 1 set mc_p_pitch = 44 set mc_i_pitch = 65 set mc_d_pitch = 32 set mc_cd_pitch = 80 set mc_p_roll = 42 set mc_i_roll = 55 set mc_d_roll = 28 set mc_cd_roll = 80 set mc_p_yaw = 40 set mc_i_yaw = 70 set mc_cd_yaw = 75 set dterm_lpf_hz = 85 set dterm_lpf_type = PT1 set dterm_lpf2_hz = 150 set dterm_lpf2_type = PT1 set mc_iterm_relax_type = GYRO set mc_iterm_relax_cutoff = 12 set d_boost_factor = 1.350 set d_boost_max_at_acceleration = 5000.000 set d_boost_gyro_delta_lpf_hz = 60 set antigravity_gain = 2.000 set antigravity_accelerator = 5.000 set tpa_rate = 10 set tpa_breakpoint = 1300 set rc_yaw_expo = 70 set roll_rate = 80 set pitch_rate = 80 set yaw_rate = 70
Videos with 7-inch Alfa Monster
Here are some videos recorder with my Alfa Monster during the 2019 flying season.