I really like the simple design of the HGLRC Draknight O4, but the camera soft mounting just doesn’t seem to work properly and introduces jello/vibration into the video. That is a major drawback on this quad, and unfortunately it really hurts the overall experience. Let’s take a closer look in this review.
What other O4 micro quads do I recommend? Check out this buyer’s guide: https://oscarliang.com/micro-drone-dji-o4-lite-comparison/
Where to Buy
Product Page:
Comes with These Accessories:
- 8x GF2023 propellers (2 sets)
- 2x LiPo straps
- 4x rubber grommets for the O4 Air Unit
Specifications
- Frame: Draknight 2 Inch O4 Version
- Stack: HGLRC SPECTER 15A ELRS AIO
- MCU: STM32F411
- Gyro: MPU6000
- FC Firmware: ZEUSF4EVO
- ESC Firmware: Q-H-50 (Bluejay)
- Camera/VTX: DJI O4 Air Unit
- Motors: HGLRC SPECTER 1003 10000KV
- Propellers: GF2023
- Optional Receiver: ELRS 2.4G / TBS Nano 915MHz
- Wheelbase: 93mm
- Overall Dimensions: 80 × 88mm
- Weight:
- Without battery: 61.9g
- With 2S 750mAh LiHV: 97.2g
Design
The frame itself is easy to build and maintain. You only need to remove four screws to take off the top cage and access the electronics inside.
The soft-mounting platform is quite unique — I have never seen this design before. The camera cage is separated from the main frame and connected by a TPU part that acts as a vibration dampener. This allows the camera cage to move up and down, left and right, and you can even twist it by hand.
There is also a dedicated TPU mount on top of the frame for installing a GPS module, although GPS is not included. However, the FC only has two UARTs: one is used by the ELRS receiver, and the other is for the DJI O4. So there really is no UART left for GPS. SoftSerial is possible for GPS, but I would not recommend it because it is not fast enough and is unlikely to be reliable for Rescue mode.
There is also a rear spoiler made from 3D-printed TPU. I am not sure if it actually does anything apart from adding a bit of weight and drag, but it does look cool.
The Draknight O4 has an onboard buzzer/LED board at the rear. The LEDs can be configured in the Betaflight LED tab for different functions, such as warnings or changing with throttle level. By default, they just show a blue light. They are very bright, and you can see the quad quite well at night.
The buzzer, on the other hand, is a little disappointing. It is very quiet, almost as quiet as the motors using DShot beacon.
There is a small 16V 100uF capacitor soldered to the power input for noise filtering. In my opinion, that is a bit too small. Personally, I would have used 220uF minimum for a 2-inch quad. For capacitor recommendations: https://oscarliang.com/capacitors-mini-quad/
It runs props out, and the propellers are friction-fit, so no mounting screws are required.
Installing the DJI O4 Air Unit
Mine did not come with the DJI O4, so I had to install my own.
You will need the original camera adapter that came with the O4 in order to install the camera in this drone.
Note that it does not come with a cable, so you have to use your own. The FC also does not have a connector for the O4, so you will need to cut the cable and solder it directly to the FC. Slightly annoying — I really wish HGLRC had pre-soldered the cable to the FC so users could just plug it in.
When it comes to soldering, it is not the easiest job because the solder pads are quite tiny. If you are not confident with soldering, get the pre-installed O4 version instead.
At least the Ports tab and OSD are already configured out of the box for the DJI O4, which is a nice bonus.
HGLRC recommends powering the DJI O4 directly from the battery, probably because the onboard 5V BEC is not powerful enough, so I soldered the O4 power to the battery lead pads.
Jello Issue and Flight Performance
The soft-mounting platform for the camera is an interesting idea, but in my experience it does not work well.
It is simply too flexible. The camera can move in all directions, which creates vibration and jello that is noticeable even in the goggles. Applying Gyroflow to the recording does not help at all — in some cases, it actually makes it look worse. If you want to produce cinematic footage, this is just not usable.
I am not sure if HGLRC really tested this properly before production. I have seen a number of complaints online describing the exact same jello issue, so this clearly looks like a design flaw rather than an isolated case.
If you ignore the jello, the quad is actually quite enjoyable to fly. It handles well, feels responsive, and stays nicely locked in. It is not very powerful, but it can still do most basic freestyle moves, which is exactly what you want for ripping around small parks and flying through tight gaps. If you fly over grass fields like I do, this quad can take a beating and actually makes a decent practice quad too.
It is a shame the jello ruins the experience, because as it stands, I cannot recommend this quad due to that issue.
Some more flight stats:
- It hovers at around 30% throttle
- 2S 550mAh: 3–4 minutes
- 2S 750mAh: 5–6 minutes
- 2S 850mAh: 6–7 minutes
One more thing to note: the props can come loose over time because they are only friction-fit, so make sure to push them all the way on before every flight.
PID and Filter Tune
It comes with a custom tune, but it is very conservative. Filters are mostly close to default values, and the PID values are quite low for a 2-inch quad. There is definitely room for improvement.
There is 8MB of flash memory for Blackbox logging, so you can tune it if you want. Here are my tuning tutorial: https://oscarliang.com/pid-filter-tuning-blackbox/
How to Setup
Firmware:
- The FC target is ZEUSF4EVO, and it came loaded with Betaflight 4.5.2. The original CLI diff can be found here.
- ESC firmware is Bluejay, 0.19, 48kHz (Q-H-50).
- Onboard ExpressLRS receiver: HGLRC Hermes 2.4GHz (Firmware 3.2.1).
- Propellers mounting: motors are reversed direction.
To setup for first flight, I did the following:
- Bind ELRS Receiver: Plug in the USB cable to the flight controller, the onboard ELRS receiver will go into WiFi mode after waiting a minute. Join the WiFi network “ExpressLRS_RX”, go to 10.0.0.10 in your browser, and enter bind phrase. And binding was done. For more detail: https://oscarliang.com/bind-expresslrs-receivers/#Method-3-Entering-Bind-Phrase-in-Web-UI
- Pair O4 to Goggles 3:
- Presets tab: make a backup of the current settings (press the Backup button); Load ExpressLRS preset based on your ELRS packet rates, how to do: https://oscarliang.com/rc-link-preset-betaflight/
- Receiver tab: enable Telemetry
- Modes tab in Betaflight Configurator: Configure the switches for arming, angle mode, beeper, and turtle mode.
- OSD tab: select HD Video Format, and load my CLI settings: https://oscarliang.com/betaflight-osd/#HD-without-GPS.
- PID Tuning tab: set your own rates, here’s my rates: https://oscarliang.com/rates/#My-Rates
Conclusion
The HGLRC Draknight O4 has a lot going for it on paper. It is lightweight, simple, easy to maintain, and actually flies pretty well for a sub-100g micro quad. Unfortunately, the camera soft-mount design is fundamentally flawed and causes serious jello in the footage.
That is a huge problem on a quad built around the DJI O4 Air Unit, because good video quality is one of the main reasons to buy it in the first place.
If HGLRC redesigns the camera mount, this could become a very solid little quad. But in its current form, I cannot recommend it.
