Review: Holybro Kopis Freestyle 4-inch FPV Drone

by Oscar
Holybro Kopis Freestyle 4 Inch Fpv Drone

The Holybro Kopis Freestyle 4-inch FPV drone offers both HD and analog versions. It’s intended for freestyle flying but I found it’s more suited for cruising and long range. Also it can benefit from some PID and filter tuning in Betaflight, which I will share in this review.

Where to Buy Kopis Freestyle

The HD version comes with the Caddx Nebula Nano and Vista Air Unit (DJI FPV System), while the Analog version comes with Foxeer Micro Razer FPV camera and Atlatl HV Micro 800mW VTX.

Receiver options are SBUS from the Vista, or Crossfire Nano RX.

Holybro Kopis Freestyle 4 Inch Fpv Drone Zipper Case Unbox

It comes in a soft roomy zipper case with accessories.

Flight Performance

See flight video here and decide for yourself how it flies.

For me, the tune is okay, there’s room for improvement for sure. It has some oscillations at higher throttle and prop wash, but it’s not impossible to get some smooth flying with the stock tune. I can try to improve the tune, let me know if that’s something you are interested to see.

With a 4S 850mAh LiPo, I get about 5 to 6 minutes of flight time.

Closer Look at the Holybro Kopis Freestyle

Here’s the specs of the Holybro Kopis Freestyle 4inch FPV drone:

  • Flight Controller: Kakute F7 Mini V3
  • ESC: Tekko32 F3 35A 4in1 ESC
  • Motor: T-Motor F1404 3800KV
  • Propeller: Gemfan Hurricane 4023 tri-blade
  • VTX: Caddx Vista
  • Camera: Nebula Nano
  • Battery connector: XT30
  • Recommend Battery: 4S 650~850mAh
  • Weight without LiPo: 180g
  • Weight with 4S 850mAh: 277.5g

Holybro Kopis Freestyle 4 Inch Fpv Drone Lipo Battery Top

It’s almost 20g heavier than the Flywoo Explorer which uses the same sized motor and prop. That explains the decrease in flight time. But the arms on the Kopis are wider and tougher (8mm vs 6mm).

The frame wheelbase is 180mm, with 2mm thick bottom plate and 3mm thick arms.

Holybro Kopis Freestyle 4 Inch Fpv Drone Bottom Plate

The FPV camera sticks out of the frame just a tiny bit, but protected by a 3D printed TPU ring around the lens.

Holybro Kopis Freestyle 4 Inch Fpv Drone Fpv Camera Nebula Nano

FC and 4in1 ESC are a 20x20mm stack. The FC is a tiny yet powerful one, offering 6 UART’s. There’s a big low ESR capacitor soldered to the ESC power pads for noise reduction. Caddx Vista is located at the back.

Holybro Kopis Freestyle 4 Inch Fpv Drone Fc 4in1 Esc Stack Vista

The Kopis Freestyle is using 1404 motors with 4inch tri-blade propellers, which is a similar setup we have been seeing on those popular 4-inch long range models.

It’s already got a power cable for the Naked GoPro soldered to the board, to be specific it’s for the BetaFPV BEC board (hero 6). But make sure to pull the yellow pin out, which is known to sometimes cause issues to the GoPro. The same TPU mount actually works for the SMO 4K camera too, all you have to do is to remove the little piece at the bottom of the mount.

Holybro Kopis Freestyle 4 Inch Fpv Drone Naked Gopro Tpu Mount

I love the fact that you can push the antenna into the frame so it doesn’t stick out and wobble during flight that causes frame resonance and mess up gyro data. And if you want more range you can just pull it out.

Holybro Kopis Freestyle 4 Inch Fpv Drone Vtx Rx Antenna Mount

It has a buzzer which helps when you crashed and lost your quad. A beeper is so important but often missing in many BNF so it’s great that Holybro added it in this build.

Holybro Kopis Freestyle 4 Inch Fpv Drone Buzzer Beeper

Holybro also sent me a nano GPS module (UBLOX M8 5883) with the Kopis Freestyle, which I assume is intended for this quad if you wish to fly long range. You can get it from here: https://oscarliang.com/product-463g

Holybro Nano Ublox M8 5883 Gps ModuleI wish the battery pad is longer and more sticky, i’d probably replace it with some Ummagrip.

Holybro Kopis Freestyle 4 Inch Fpv Drone Battery Pad Top Plate

How to Setup

Here’s the CLI dump from the Holybro Kopis Freestyle 4inch (not stock setting, just my last working dump).

  • FC: KAKUTEF7MINIV3, loaded with Betaflight version 4.1.6
  • ESC: BLHeli_32

Bind Crossfire receiver, check in receiver tab if you get response from stick movement.

Check if the motors are running correctly in the motors tab. DO NOT mount props while testing motors on the bench. Use a smoke stopper or bench power supply if you have one. The quad is configured to run “normal” rotation (props in).

Betaflight setup:

  • In Configuration tab, change arming angle to 180
  • Enable Airmode
  • Enable ESC DShot (enable RX_SET only) I know it has buzzer but it’s good to have backup
  • In Modes, assign switches to Arm / Beeper / Flip over after crash
  • In Receiver Tab, enable RSSI Channel (I selected AUX8), and pass LQ or RSSI via a channel (I am using Channel 12, as DJI doesn’t support displaying LQ or RSSI yet)
  • Setup OSD elements

Activate and update Caddx Vista. Do this with a fan blowing as it can take several minutes and you don’t want the VTX to overheat. Stock firmware is 1.05 and you want the latest version 1.06 if you want to run 50Mbps mode.

Finally bind it to to DJI FPV Goggles.

Further Reading:

You can now mount the props and get ready for first flight!

Kopis Freestyle Needs Better Tune (WIP)

Update Betaflight to the latest version (4.2.9 when I wrote this). If you wish to go back to the original version/settings, just flash it to 4.1.6 and apply the CLI dump I linked in “How to Setup”.

First thing you should do is to enable RPM filter. You should take advantage of the expensive BLHeli_32 F3 ESC, it supports Bi-directional DShot out of the box. By the way, 1404 motors have 12 poles.

Set motor Idle to 7.

Filter / PID need re-tuning. Update coming soon.

Conclusion

The Kopis Freestyle 4inch is not a “under-250” FPV drone unless you are willing to use a very small LiPo that gives you little flight time. With a naked GoPro and 4S 850mAh LiPo it will be near 300g. If 250g is your thing, you should consider the analog version instead.

Although it’s marketed as a “freestyle” FPV drone, I think it’s more suited as a cruiser. The 1404 motor and 4-inch prop combo is made popular by the ultra-light long range setup, it’s really efficient and gives you fantastic flight time. However it isn’t particular a powerful combo and struggles when you do extreme maneuvers. I demonstrated this in my review of the Flywoo Explorer, even it was a much lighter quad.

Given the weight and driving 4-inch 3-blade props, the Holybro Kopis Freestyle 4-inch will definitely benefit from larger motors if acrobatics is your main focus. 1506 or even 1606 should be considered.

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