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!

Alfa Monster 7"

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.

Pros

Cheap
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

Cons

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

Alfa Monster 7 inch freestyle quadcopter

INAV Reference Tune

INAV 2.6

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