Review: Holybro Kopis Mini 3″ BNF FPV Drone with DJI Air Unit

The Holybro Kopis Mini packs all the advantages of the DJI FPV system into a 3″ form factor – equipped with full size DJI Air Unit and designed to be used with the DJI FPV remote out of the box.

Where to Buy Kopis Mini

DJI Version With DJI Air Unit:

DJI Version with Caddx Vista:

The DJI Air Unit is better than the Caddx Vista in many ways, it has onboard 1080p HD recording (unaffected by focus mode or any interruption you see in the goggles), audio in recording, and dual antennas for more reliable signal. However it’s heavier and slightly more expensive. See this post for detail.

Unfortunately the Kopis Mini is slightly over 250 grams even with the smallest battery I recommend. If sub-250 weight is important to you, there is also the analogue version.

Analogue Version: 

Get some 4S 650mah LiPo batteries for this quad:

Get spare props (T-Motor T76) because it only comes with 1 set

Emax Avan 3×2.4×3 is another good choice:

The Kopis Mini comes in a fancy carry case, big enough for a 5″ quad.

But the package is minimal, not many accessories included, only a set of props, a spare cable for the Air unit, couple of zip ties and some spare C-clip for the motors.

Specs

  • FC: Kakute F7 HDV
  • ESC: Tekko32 F3 4in1 45A ESC (BLHeli_32 20x20mm)
  • Motors: T-motor F1507 3800KV (T-mount 1.5mm shaft)
  • Propellers: T-motor T76 (T-mount)
  • Carbon Fibre Frame
    • 2mm top plate
    • 3mm unibody bottom plate (and arms)
  • Buzzer included
  • Weight: 206g without battery; 293g with CNHL 4S 650mah

Close Look at the Kopis Mini

The frame supports 3″ propellers, and has a wheelbase of about 148mm.

The Kopis Mini doesn’t have a radio receiver, it gets the RC signal from the DJI Air Unit (SBUS protocol), and you can bind it to the DJI FPV remote. Of course you can use other radio transmitters, but you have to install your own receiver as Holybro doesn’t offer any receiver options at purchase.

Very nice looking quad. All the USB connectors and SD card slots are easily accessible without special adapters.

Camera angle is adjustable – but the front motors get in the way of the screw driver, so you will  need a L-shape M2 hex key wrench for this (or screwdriver bit). I wish this is included.

The lens does stick out of the frame a tiny bit and prone to damage in a crash. I think it’s best if you can get a protective lens cap like this.

They recently changed the props mounting design of the motor, it used to be M5 threaded shaft but now a 1.5mm shaft with M2 mounting holes. And they also ship with different prop now too.

The F1507 motors from T-Motor are 3800KV, which is relatively low for 3″ on 4S, indicates it’s designed to handle slightly heavier props (higher pitch) than the typical 3″ toothpick props.

The Antenna mounting and placement are questionable, perhaps they did this for better durability, but it’s certainly not the best for signal. I think they placed the antennas way too close to the carbon fibre, and they can be easily blocked by the frame when spinning around in the air.

I wish Holybro would design a 3D printed antenna rear mount for holding the antennas (something like my Martian). It feels like they rushed it to get this model out of the door ASAP.

The other problem I found was the Lipo strap – it’s impossible to have the strap right in the center of the frame, because the Air Unit is in the way. To hold the battery properly, I have to slide the battery slightly forward and that’s not great for CG. Although I haven’t really noticed an issue in flight performance because of this, it’s something to take note of.

The Kopis Mini can be easily taken apart if you want to do repairing on it. There are only four screws on the top plate. And those screws all have thread locks, what a nice touch!

The DJI Air Unit is mounted under the top plate with just double sided foam tape. Personally I’d advice against this and use some proper mounting like 3D printed parts. But I guess this is more cost effective for the manufacturer, and better for weight-saving too. Only time will tell if this will hold up to long term usage, so far it has survived a dozen of crashes.

Just like any builds with the DJI Air Unit, cabling is very clean and simple. The Kopis Mini uses the Kakute F7 HDV flight controller, and it has a port that connects directly to the Air Unit.

Normally the 4in1 ESC sits under the flight controller, but interestingly, Holybro decided to mount the ESC next to the FC instead, there are a couple of benefits:

  • The two boards have different mounting holes – the FC has M3 30x30mm, while the ESC is a smaller board with M2 20x20mm, and that takes less space
  • Having the FC and ESC spaced out in the frame, frees up room for the DJI Air Unit
  • No need to worry about shielding and interference between the 4in1 ESC and FC

Soldering quality looks good – not fantastic but it will get the job done.

The FC is soft mounted with rubber grommets. I am happy to see they didn’t over-tighten the FC screws like some other BNF manufacturers do, so soft mounting can work effectively.

And it has a buzzer which is lacking in a lot of 2-inch and 3-inch BNF builds – especially when you have an expensive DJI Air Unit on it and tends to get very hot, you’d want to find your quad ASAP after you crash it to avoid overheating.

But the buzzer can be annoying during setup and Air Unit firmware update :) It beeps so loud I had to put tape over it.

It has a 35V 1000uF capacitor soldered to the power pads on the ESC for noise reduction.

The TPU mount for the capacitor and XT30 also acts as Air Unit antenna holder, it prevents the MMCX connectors from popping out – nice touch.

It’s strange that they used countersuck bolts for the FC, but didn’t for the ESC. It would have been nice to have a “all flat” surface on the bottom so we can “bottom mount” the battery if we choose too. ( I guess I am just being picky :) )

And it’s a nice touch that they added some rubber feet under the arms.

Setting up

Holybro did a great job with their online manual for this drone.

If you are totally new to FPV drones, check out my tutorials to get started:

Here are what I did to setup the Holybro Kopis Mini for the first flight:

  • Activate DJI Air Unit, update firmware to the latest (comes with V1.3) and bind it to FPV goggles and remote
  • Go to Betaflight, it comes with BF 4.1.2 version
    • No need to update, but if you are having performance issues, try to setup RPM filters, and try updating to BF4.2
    • Configuration tab – arming 180, DShot Beacon
    • OSD
    • Rates

Conclusion

The Holybro Kopis Mini won’t have the same speed and handling of its bigger 5″ brother – the Kopis 2, but it’s small, lightweight, and if you crash it’ll do less damage. It’s been very reliable, and the crash-resistance gives me a lot of confidence.

For a 3″, it might appear to be a little heavy at 293g AUW, but it’s a rocket! (I might be exaggerating a little, but it is very fast)

You have to take into consideration that other light weight 3″ normally use much smaller motors such as 1105 or 1204 with skinny 3″ propellers. The 1507 motors on the Kopis Mini are absolute powerhouse and it can produce a lot of torque and lift with these T76 props.

The heavy weight actually gives this quad more momentum and “hang time”, makes it more fun to fly freestyle with and performing inverted moves.

Get the Kopis Mini DJI Version from:

4S 650mah LiPo batteries:

Spare props (T-Motor T76): https://oscarliang.com/product-vt4v

Spare props (Emax Avan 3×2.4×3): Amazon: https://amzn.to/33vWnKM


These bigger motors however can draw a lot of amps when you push it hard, but if I take it easy, a 4S 650mah gives me about 3:30 to 4 minutes of flight time (cruising).

Pros

  • It has DJI Air Unit – allows 1080p HD recording and audio which is missing in the Vista
  • Reliable components and great build quality
  • Flies very well out of the box
  • Simple to setup (especially so if you use DJI FPV remote)
  • Comes with buzzer
  • Tons of power – can even carry a GoPro
  • Nice online manual

Cons

  • Not cheap
  • Antenna placement / mounting is a little sloppy
  • Would be nice if they included spare props
  • More than 250g with battery
  • No receiver options – you can use other radios but you’d have to buy receiver separately and install it yourself; Not a problem if you use DJI remote

1 thought on “Review: Holybro Kopis Mini 3″ BNF FPV Drone with DJI Air Unit

  1. Adam

    Hey Oscar, thanks for the guide on the Kopis Mini. I picked up those Avan props on your recommendation because the T76 are hard to get. Unfortunately they don’t work on the motor, the aggressive bottom ‘wings’ hit the motor before the prop sits all the way down

    Reply

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