The Pirx Seven 7-inch FPV frame
Ladies and gentlemen, I give you Pirx Seven! The 7-inch FPV frame designed in-house to give me, and you obviously, a versatile platform for long-range, cinematic takes and freestyle!
Let's begin with the question: why did I have to design my own frame? There are plenty of good frames out there! True, there are good 7-inch FPV frames, but all of them have some problems: props in the view, very little space inside, thin arms, asymmetrical arms, no place for a huge battery, limited accessories and dozens of other minor things.
Pirx Seven overcomes some of them (creates a few others as well, but let's not shout about it) and truth to be told, it's the best 7-inch frame I own. After all, I designed it to solve problems I was having :)
- weights around 210g before equipment
- dead cat setup - front and rear arms are fully interchangeable
- No props in the view! With a very wide angle camera you might see tips of the props, but only that
- 6mm arms are super stiff to shift the resonance frequency high enough to be filtered without interfering with flight performance
- 4mm bottom plate and 2mm top plate are connected with 12 standoffs in total resulting in pretty nice structural strength and stiffness
- accepts ONLY micro size FPV cameras as well as popular micro-split-like cameras like Caddx Tarsier or RunCam Hybrid 4K
- fits DJI FPV Air Unit and camera but there is no official mount for the Air Unit yet
- 20x20mm pattern holes in the front
- 30,5x30,5mm and 20x20mm pattern holes in the middle where the center of gravity meets the center of thrust
- 30,5x30,5mm and 20x20mm pattern holes in the rear section for any equipment you want
- has a dedicated place for Matek Optical Flow & Lidar Sensor
- accepts LiPo on the top and the bottom side as well. Top mount is recommended as it moves CoG closer to the thrust plane
- variety of 3D printed accessories for cameras and antennas
- FPV camera is mounted on the 3D printed bracket by design! During the crash, it's better to break a small 3D printed element than an expensive camera
- Vertical plates in the front are tight fit by design and have to be precisely sanded/filed to fit slots in the horizontal plates!
- All M3 holes are tight fit by design as well! Some torque will be required to put screws into them. It's to make sure that arms will be rightly in place and not move at all.
Does it fly?
Yeap! Take a look at fly videos:
More about the frame
Additional, 3D Printed, parts
Armattan Productions does not offer 3D printing service, you will have to print some extra elements:
- Micro FPV camera adapters
- Micro FPV camera adapters (alternative)
- 4mm spacer for the front bumper
- GPS plate
- GPS and SMA plate L
- GPS and SMA plate R
- Horizontal SMA adapter (Flexible TPU)
- Vertical SMA adapter A
- Vertical SMA adapter B
- GoPro Session Flexible Mount (attach with zip-ties)
- GoPro Hero 6/7 30deg Mount (attach with zip-ties to front bumper)
Note that only an FPV Micro Camera adapter is required. All the rest are optional!
Or you can download all STL files from here: http://bit.ly/2SPdpxW
- Frame: Pirx Seven
- Motors: Brotherhobby 2507 Avenger v2 1500KV
- Propellers: HQProp 7x4x3
- Flight Controller: Holybro Kakute F7
- ESC: Holybro Tekko32 HDV
- VTX: Matek 5.8GHz HV VTX
- FPV Camera: RunCam Micro Eagle
- GPS: Beitian BN-880 GPS module
- RX: FrSky R9MM or TBS Crossfire Nano
Settings & Tuning
Pirx Seven reference setup is based on INAV 2.3 as it provides full GPS long-range support as well as very good acro / freestyle flight performance. Below are key settings like mixer, PIDs, filtering and rates that you can copy-paste into INAV CLI instead of manually tuning the drone. Please remember, that if your setup is much different from the reference, you might have to adjust it accordingly.
Pirx Seven is an asymmetric frame in a dead cat configuration. It will fly just fine with standard quadcopter mixer, but informing flight controller about the actual motor positions can improve flight performance.
mmix 0 1.000 -0.900 0.800 -1.000 mmix 1 1.000 -1.000 -0.800 1.000 mmix 2 1.000 0.900 0.800 1.000 mmix 3 1.000 1.000 -0.800 -1.000
feature DYNAMIC_FILTERS set looptime = 500 set gyro_hardware_lpf = 256HZ set gyro_lpf_hz = 85 set gyro_lpf_type = PT1 set gyro_stage2_lowpass_hz = 150 set dterm_lpf_hz = 90 set use_dterm_fir_filter = OFF
set mc_airmode_type = THROTTLE_THRESHOLD set mc_p_pitch = 45 set mc_i_pitch = 58 set mc_d_pitch = 32 set mc_p_roll = 40 set mc_i_roll = 45 set mc_d_roll = 27 set mc_p_yaw = 75 set mc_i_yaw = 75 set dterm_setpoint_weight = 0.850 set pidsum_limit_yaw = 400 set mc_iterm_relax = RPY set d_boost_factor = 1.500 set d_boost_max_at_acceleration = 3500.000 set d_boost_gyro_delta_lpf_hz = 50 set antigravity_gain = 2.000 set antigravity_accelerator = 5.000 set rc_yaw_expo = 70 set roll_rate = 75 set pitch_rate = 75 set yaw_rate = 70
set min_check = 1050 set max_angle_inclination_rll = 500 set max_angle_inclination_pit = 500