85mm whoop is the sweet spot for the DJI O4 — it’s powerful enough to carry the extra weight of the air unit while not being too big or noisy for flying in parks. The Happymodel Mobula8 is quite an old design, but Happymodel has updated it with a new canopy to support the O4. I’m more interested in Happymodel’s O4 Wide Angle Lens solution (they call it the FOV extender). It increases the camera’s field of view (FOV), making the flight experience more enjoyable and stabilized footage more usable — similar to how the Flywoo wide-angle lens works. It will be interesting to find out which wide-angle lens performs better.
Looking for micro quads with DJI O4? Check out this round-up and my recommendations: https://oscarliang.com/micro-drone-dji-o4-lite-comparison/
Where to Buy
You can get the Mobula8 O4 HD Whoop from:
What’s in the Box
- Stickers
- UV filter
- ND8 filter (pre-installed)
- ND16 filter
- Spare camera canopy
- Two extra sets of propellers
- HQ 2x2x3
- Gemfan 2023R triblade
- Screwdriver and prop remover
Specifications
- Wheelbase: 85mm
- Flight Controller: CrazyF405HD ELRS AIO FC
- ESC: 12A 4-in-1 (Bluejay firmware)
- Receiver: Built-in ExpressLRS 2.4GHz
- FPV Setup: DJI O4 Air Unit + Wide Angle FOV Adapter
- Battery: 2S (XT30 connector)
- Motors: EX1103 11000KV
- Propellers: Gemfan Hurricane 2023 tri-blade (1.5mm shaft hole)
- Size: 120mm × 120mm × 53mm
- Weight:
- Without battery: 52.6g
- With 2S 550mAh: 82.2g
For an HD whoop, that’s impressively light — only 82g including battery.
Mobula8 Build & Design
The Mobula8 is a 2-year-old design, and they are basically using the same hardware. However, in this new version, Happymodel updated the canopy, designing it specifically around the DJI O4 Lite Air Unit. They also created a wide-angle lens for it, which improves recording quality and overall flight experience.
Camera Mount & Canopy
The O4 camera is hard-mounted inside the canopy — there’s no soft mounting.
The O4 Lite antenna dangles out the back without any support, which could be a weak point. It can get close to the props or snag during crashes. I wish Happymodel had mounted the antenna more securely.
An ND8 filter comes pre-installed out of the box. If you plan to fly indoors where there’s not a lot of lighting, you may want to remove it first. ND16 and a transparent UV filter are also included. You definitely want either an ND or UV filter installed because the camera is very exposed — these filters provide some protection to the lens during crashes.
Happymodel O4 Wide Angle Lens
The highlight of the Mobula8 O4 is the wide-angle lens.
If you’ve flown the O4 Lite in stock form, you’ll know the FOV is quite narrow — everything feels closer than it actually is. The wide-angle lens dramatically improves the flight feel.
However, you may see corners and edges in 4:3 mode. It also adds a bit of extra weight to the quad.
Installation is relatively simple — just clip the wide-angle lens onto the O4 camera. It’s secured by two tabs at the back. This is similar to Flywoo’s older design but feels more secure. However, it shares similar issues with lens glare and internal reflections due to the extra glass. Flywoo’s new wide angle lens solution is better in that regard because it replaces the original O4 housing and lens entirely.
The lens weighs just over 3g, about 2g lighter than Flywoo’s new solution.
The mount width is 18mm. The lens itself is much wider than 18mm and sticks out quite a bit. It also gets in the way of the front canopy screws — accessing them requires bending the canopy to move the camera out of the way.
The ND filter is held in place by two tabs and is very tight — installing or removing it isn’t easy.
Image Quality
The FOV is wider than Flywoo’s — you see more of the surroundings — but the fisheye effect is also more noticeable when comparing Happymodel and Flywoo side by side. That said, I don’t find the fisheye effect problematic. It feels fine in flight and is totally flyable.
You can see the lens housing in the corners inside the goggles. It’s even more noticeable in the air unit’s onboard recording — it looks like you’re looking through a tunnel.
Stabilization works well in Gyroflow. Processing the HD footage crops out most of the vignette, and you can eliminate nearly all of it by setting the FOV below 1.0. I set mine to 0.97, and almost everything disappears.
I also noticed slightly reduced sharpness around the edges, but that’s expected with any wide-angle lens.
Flight Performance
The quad hovers at around 21% throttle. Flight performance is surprisingly smooth and stable — better than expected, especially given the unusual PID tune. The filters and PIDs are set conservatively, so there’s definitely room for improvement.
It’s also worth noting that it’s not using bidirectional DShot, so the tune isn’t fully optimized.
For a 2S micro quad, it’s quite powerful and feels agile. However, there is noticeable prop wash and some instability when recovering from dives and split-S maneuvers. You could try reversing motor direction and running “props out” — that may help reduce yaw washout.
It’s also surprisingly quiet — from about 100 meters away, you can barely hear it.
In fact, it feels more like a small 2S toothpick than a traditional whoop. This might be one of the best-flying O4 Lite tiny whoops I’ve tested so far.
That said, there’s definitely room for improvement in the tune. As you can see, filtering isn’t quite sufficient and the quad sounds a bit noisy. I also think the PID values could be refined further.
With a 2S 550mAh LiHV battery, I’m getting around 5 minutes of freestyle flying. That’s pretty efficient and a solid flight time for this setup.
How to Set It Up
I don’t think Happymodel put much effort into configuring Betaflight. Even the craft name is wrong — it’s labeled “Mobula7”.
Original CLI can be found here.
The DJI O4 isn’t activated out of the box. You’ll need to connect it to DJI Assistant 2 (Consumer Drone Series) via USB to activate it. The Air Unit must be powered during activation, so make sure a LiPo battery is plugged into the drone.
To bind ExpressLRS, use the WiFi method. The receiver is a Happymodel EP1/EP2 2.4GHz RX running ELRS firmware 3.0.1, connected to UART2.
Here are the Betaflight changes I recommend:
- Enable DShot Beacon
- Change channel map to “Default”
- Enable Telemetry in the Receiver tab
- Pitch channel has slight jitter — set RC deadband to 2
- Set up your arm switch and beeper in Modes
- In the OSD tab:
- It came with the wrong format selected (even though HD was shown).
- Select “Auto”, save, then switch back to “HD”.
- Enable and position the OSD elements you want.
- Disable “Core Temperature” — it’s not useful.
Manual: https://www.happymodel.cn/wp-content/uploads/2023/06/Mobula8-O4-Manual-document.pdf
Final Thoughts – Is It Worth It?
I was initially a bit put off by the “old school” design. It felt like Happymodel didn’t put much effort into updating the Mobula8. But after flying it, I kind of understand their approach — they’re simply recycling a platform that already works well.
And honestly, the Mobula8 flies well. It’s smooth, agile, quiet, and fun. Paired with the O4 and the wide-angle lens, it becomes a really solid combo. It might not look flashy, but you won’t be disappointed by how it performs in the air.
If you want a micro whoop with DJI O4, this is definitely among the better options in terms of flight performance.
Get the Mobula8 O4 from:
The wide-angle lens is a great addition. Image quality isn’t quite as good as Flywoo’s newer solution, but Happymodel’s version is lighter and better for overall flight performance. Flywoo’s approach feels more polished and streamlined, with slightly better image quality, while Happymodel’s solution feels more DIY — but still delivers a widened FOV and solid results with less weight penalty.
Overall, it’s a strong package — especially if flight feel matters more to you than absolute image perfection.
