Shortly after the official release of the DJI O4 Air Unit, FlyFishRC updated their line of FPV frames to support this new HD digital transmission system. The company also introduced compatibility kits for existing O3 setups, allowing pilots to upgrade without spending a fortune or rebuilding their drones completely.
The DJI O4 Pro Air Unit introduces notable changes in the transmission module (VTX) and camera compared to the DJI O3, affecting frame compatibility. The O3 Air Unit’s module measures 30×30×6 mm with a 20×20 mm mounting pattern, while the O4 Air Unit Pro is larger at 33.5×33.5×13 mm and supports both 20×20 mm and 25.5×25.5 mm patterns. Additionally, the cameras differ by size and mounting pattern (14mm vs 16mm screw distances), requiring either dedicated frames or adapter kits. Another key difference that affects frame design is that O4 Pro uses two antennas, while its predecessor had only one.
All FlyFishRC frames natively support both O3 and O4 VTXs, but when it comes to the camera, they require a different camera cage for each camera type. The Volador II family and the Tony 5 have already been upgraded to support O4, and conversion kits are available for the Atlas 4 and Tony 5.
FlyFishRC DJI O4 Air Unit frames
Disclosure: I received these fame kits for a product review collaboration with FlyFish-RC. Although the products were offered for free, all opinions in this article remain my own, and the sponsor did not influence me. With over five years of proven presence in the FPV industry, the company has built a solid reputation for reliability and innovation. It remains committed to developing cutting-edge products that help pilots achieve precision, performance, and creative freedom in every flight.
I was lucky enough to get my hands on a DJI O4 Air Unit Pro kit before its official release, so I didn’t waste any time and installed it on one of my reliable FlyFish frames. This early hands-on experience not only showcased the system’s advanced capabilities but also offered valuable insights into its integration within existing FPV setups. Installing the O4 Pro into my existing Volador II VD6 frame, previously equipped with the O3 system, came with the following challenges:
- First, I needed to 3D print a compatible dual-antenna mount to replace the stock single-antenna mount. Luckily, the STL file was available on Thingiverse.
- The second issue was caused by the different size and geometry of the new O4 camera compared to its predecessor. At that time, since the O4 Pro hadn’t been officially announced, no online resources were available to print a dedicated camera mount or gauge. In the end, taking the risk of leaving the camera lens too exposed in the event of a crash or mounting it too tightly without the vibration isolation provided by a proper frame bracket, I installed the O4 Pro camera into the existing O3 mount and continued using it that way until last week.
After seeing my DJI O4 Pro review, Robbie from FlyFishRC mentioned they’d soon release dedicated O4 camera mounts and promised to send me a test sample. When the package arrived, I was genuinely excited to find not just the expected conversion kit but two complete frame sets! It was an awesome surprise, and it gave me the perfect opportunity to rebuild my setups from the ground up, fully optimized for DJI’s new O4 digital FPV system.
FlyFish Volador II O4 series (Freestyle and Long-Range Cine)
The Volador series is available in four sizes (3, 3.5, 5, and 6″) and two geometry options (True-X and DeadCat). Since last month, everything has been updated to support the DJI O4 Pro Air Unit kit. Furthermore, for those who already own a build using one of these frames, FlyFish offers dedicated upgrade kits to ensure full compatibility with the new DJI O4 system. It’s a thoughtful and pilot-friendly approach, allowing existing users to modernize their setups without purchasing an entirely new frame. All brands should offer this flexibility and support for the FPV community.
I use FlyFish Volador VX5 and Volador II VD6 frames in my current FPV builds. These frames are exceptionally well-designed, offering a solid balance between durability, weight, and ease of assembly. Their robust construction and thoughtful engineering make them reliable choices for various flying styles, whether for freestyle, long-range, or cinematic applications.
The Volador II 5-6″ conversion kit with the included dual-antenna TPU mount costs $16.90, and the complete set of VD6/VX6 is $74.90. Both have yellow and black options.
After replacing the O3 camera mount on the Voldaror II VD6 with the new O4 cage, I encountered the following problems:
- My K&F Concept AVATA 2 filters are no longer compatible with the O4 Pro Air Unit, as their mounting system does not fit the new camera frame.
- The side CNC aluminum frame parts are visible in FPV view, making the user experience less enjoyable.
FlyFish Fifty5 O4 Freestyle
The Fifty5 O4 frame is an excellent choice for those who want an ultra-light FPV drone compatible with 5 and 5.5″ propellers. As detailed in our FlyFish RC Fifty5 review, the frame is available as a bundle with Sword 2207 motors (1850KV | 1950KV | 2050KV) and Flash 2306 motors (1750KV | 2550KV), providing flexibility to build both 4S and 6S setups. The standalone frame kit is priced at $52.90.
According to FlyFish, “At the heart of our design philosophy for the FIFTY5 frame lies the pursuit of lightweight simplicity and durability. While our Volador VX5/6 is extremely durable and known as a flying tank, it’s not synonymous with lightweight or ease of assembly”. While the manufacturer’s product photos show a single-antenna mount, mine arrived with the new dual-antenna TPU holder.
Depending on your intended use, you can choose either a flight controller and ESC stack for increased performance and versatility or an AIO (all-in-one) board to keep the build as lightweight as possible.
Upgrade kits for FlyFish Atlas 4 and Tony 5
These two frame sets have not been upgraded yet, but if you own an Atlas 4 or Tony 4 build, you can replace the stock 03 camera mount with the one designed for the Volador VX3/VX3.5 O4. A pair of CNC aluminum camera plates with silicon insertions costs only $9.99.
Bottom line
As I’ve already reviewed these frames, I chose not to make this article too detailed or overly technical. If anyone needs help or advice building a FlyFishRC drone, feel free to drop a comment below — I’d be happy to assist!
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Shame for a deadcat frame that has no clean FPV view.