Review: Flywoo Naked O3 Lite\Ultra Conversion Kit – The Lightest DJI O3 Setup

The DJI O3 Air Unit has taken the FPV experience to the next level for many pilots. However, it’s not without its shortcomings, the primary one being its substantial weight, particularly for micro FPV drones. This is where the Flywoo Naked O3 Air Unit Lite/Ultra Kit comes into play, promising to reduce the weight of the O3 by up to an impressive 50%. If you want a lighter DJI O3 drone build, this is what you want.

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In this review, I’m going to walk you through the process of using this kit to modify your DJI O3 Air Unit, delving into the advantages and potential drawbacks to help you make an informed decision.

Why Make DJI O3 Naked?

The DJI O3 Air Unit comes in at a hefty 36 grams, which is heavy for micro FPV drones. This excess weight can seriously hinder flight performance and flight time.

The Flywoo Naked O3 Lite/Ultra conversion kit is a game-changer in this regard, allowing a weight reduction to a mere 18 grams. Alongside this, the kit also reduces the camera size from 20mm to 18mm, transforming it from a mini to a micro form factor. If you’re considering incorporating the DJI O3 into your 3.5″, 3″, or even 2″ drone, this kit is a compelling option.

Here’s a related modification we’ve explored before, the Naked DJI Vista Air Unit: https://oscarliang.com/naked-vista/

The modification removes the unnecessary, mostly plastic housing and metal heatsink from both camera and VTX. Unfortunately, this has the side effect that the VTX gets very hot much faster. But as long as you have enough airflow, tests have shown it shouldn’t be a huge issue.

However, it’s crucial to understand that the Naked O3 conversion kit is not an official DJI product. What Flywoo offers here is a DIY kit, enabling you to strip the O3 Air Unit down to its minimum components. Doing this modification will void the warranty, so please proceed with caution.

Where to Buy?

You can get the Flywoo Naked O3 Lite/Ultra Kit from:

• AliExpress: https://s.click.aliexpress.com/e/_DBMZHF9
• Flywoo: https://oscarliang.com/product-mgwa
• GetFPV: https://oscarliang.com/product-35mv
• RDQ: https://oscarliang.com/product-w620

Flywoo offers two different kits, the Lite and Ultra. They also sell pre-modified units if you don’t want to do it yourself.

Differences Between Lite and Ultra Kits

The main difference between the O3 Lite and O3 Ultra is weight. The Ultra kit is about 5 grams lighter due to the removal of micro SD card reader. This means with the Ultra, you are limited to the built-in 20GB storage for onboard video recording. If you want to retain the SD card reader, you should get the Lite kit.

Below is a comparison table detailing the specifics of the Original DJI O3 Air Unit, Naked O3 Lite, and Naked O3 Ultra:

* Overheat warning time was measured with the Air Unit sitting on the bench without airflow, a cold start, low power mode enabled, with an ambient temperature of around 25°C.

Unboxing Accessories

The Naked O3 kit from Flywoo includes CNC-machined aluminium brackets and pieces (7075 alloy) for the VTX and camera, and a variety of additional hardware. Flywoo also includes their customized dipole antennas for the O3 to replace the heavier, original 2in1 antenna, saving about 2 grams.

Here’s a quick breakdown:

• Replacement screws
• Replacement antennas
• A metal frame for board mounting
• Holders for antennas and the MIPI cable connectors
• A camera mounting bracket
• A UV lens cover (acts as lens protector)

ND Filters

After the Naked O3 modification, generic ND filters designed for the DJI O3 camera are no longer compatible. However, Flywoo has thoughtfully provided specialized ND filters specifically for the Naked O3 camera. They can be acquired here: https://oscarliang.com/product-mgwa

ND4, ND8 and ND16 are available in the box.

Potential Overheat Issues

One thing to note is that the air unit does get hot rather quickly after the mod. So, heat dissipation is something you might want to think about, especially for longer flights.

The drone, when left sitting on the ground plugged in, is prone to overheating. This is common even with the original O3 Air units or most high power VTX in fact; without airflow and cooling, the heat accumulates over time leading to overheating.

After doing the naked O3 mod, in low power mode, I experienced overheat warnings in the goggles within 2-3 minutes, with the air unit shutting down 1-2 minutes after. With low power mode disabled, the overheating warnings and shutdowns occurred even earlier. For comparison, the unmodified original O3 Air Unit can endure up to 10+ minutes before showing the overheating warning.

With that said, when installed the naked O3 in my BetaFPV Pavo Pico, I haven’t experienced any overheating warnings during flight. That’s probably because I usually take off within 30 seconds of plugging in the battery, minimizing idle time on the ground and it was pretty cool outside at 25°C. I can confidently say there’s no compromise on the image quality, DVR capabilities, or signal penetration.

It will depend heavily on your frame design, flying environment, and ambient temperature. If you have a much enclosed frame and flying in much hotter temperature, overheating could be an issue.

If you crash, the Air Unit can overheat sitting on the ground, and eventually shut down. If that happens, it will not reconnect to your goggles until you power cycle the Air Unit. This is something to think about for long-range flights where immediate retrieval is not possible.

Given the high levels of heat, although it shuts it self down when overheats to prevent further damages, it’s important to consider long-term implications for other components on the boards. While the unit has been designed to self-regulate its temperature to some extent, a lack of proper airflow during flights could cause problems and might even lead to components desoldering themselves from the board.

Mounting Naked O3

Mounting the Naked O3 is straightforward; if your drone can already accommodate a full-sized O3 Air Unit, it will fit the Naked O3 just fine. The only thing that really changes is the camera size – from 20mm to 18mm.

However, the stripped down VTX is more likely to overheat without enough airlfow to cool it down. Therefore the manufacturer recommends mounting the naked O3 in an open frame.

O3 Lite Installation

In this section, I will walk you through the installation process of the O3 Lite kit, providing a detailed, step-by-step guide on how to successfully make the conversion.

Tools You Will Need:

• Small Phillip Screwdriver
• Tweezers
• Q-tip
• (Optional) Isopropyl Alcohol, aka rubbing alcohol
• (Optional) Toothbrush

Disassembling the DJI O3 Air Unit

Start by detaching the antennas and camera from the Air Unit.

Remove all eight Phillips screws securing the top and bottom covers. Use a cloth (or Q-tips) and isopropyl alcohol to clean the blue thermal paste inside the case. The clean-up require a bit of patience, it doesn’t need to be perfect, just get as much off as you possibly can.

Detach the glued ribbon cable connecting the boards. Use a plastic tool or your fingernail to avoid causing damage to the connectors. Carefully separate the dual circuit boards from the black housing.

This leaves you with the two main circuit boards.

Working on the Main Boards

After separating the boards, proceed to strip the unit further by removing metal heat shields and cleaning the blue thermal paste very carefully. Ensure to be gentle around fragile connectors.

The metal casings on the unit are secured with clips all the way around. Gently pry them open with suitable tool, and clean off any residual thermal paste.

For thorough cleaning, I found using a soft toothbrush and isopropyl alcohol to be extremely effective.

For a more thorough cleaning, you could use an isopropyl alcohol-dipped toothbrush or even an ultrasonic cleaner. However, based on experience, a Q-tip should suffice for most cleaning tasks.

Making the Camera ‘Naked’

Disassemble the camera by removing the two screws on the back, and  unplug the coaxial cable.

After unscrewing four more small screws inside the camera, the lens module can slide out of the housing.

The cable is glued to the back housing, to remove it you might want to use a hot air gun (or hair dryer if you don’t have one) to make it easier to pull apart

The Flywoo kit provides a special bracket for the camera, which slips over the camera once the coaxial cable is reconnected. Secure the lens and cage with the four provided screws.

It also comes with a UV filter which acts as the lens protector.

Installing O3 Air Unit in New Case

The kit includes a CNC bracket for mounting the two circuit boards. Reconnect the camera and antennas before mounting the CNC parts.

Reconnect the ribbon cables between the two boards, and attach the CNC parts, ensuring proper alignment of all connectors. Pay attention to the direction of the USB-C and other connectors while aligning the internal boards.

The assembly is well-designed and robust, feeling solid once all components are securely in place.

Conclusion

Overall, the Flywoo Naked O3 Lite/Ultra Air Unit is an excellent product for those who looking to shave off some weight from their DJI O3 Air Unit. There are 3D printed alternatives, but the ease of use, precision and robustness of CNC parts are probably better bets. The design is well thought-out, and the conversion process is straightforward.

You can get the Flywoo Naked O3 Lite/Ultra Kit from:

• AliExpress: https://s.click.aliexpress.com/e/_DBMZHF9
• Flywoo: https://oscarliang.com/product-mgwa
• GetFPV: https://oscarliang.com/product-35mv
• RDQ: https://oscarliang.com/product-w620

While it may have a few caveats, such as warranty void, thermal concerns and the reduced durability, it’s benefit in weight saving and flight performance cannot be ignored especially for small 2″, 3″ and 3.5″ micro FPV drones.

So, if you’re keen to lighten your FPV drone for that extra agility and performance, this is a kit worth considering.

Spare Cable between PCB Boards

Get it from Flywoo: https://oscarliang.com/product-e06p

Spare DJI O3 Camera Lens Module

When using a non-original O3 lens, you may notice an unremovable prompt on the right side of your goggles (Camera calibration error). However, this does not affect the performance of the camera in any way.

Get it from:

• Flywoo: https://oscarliang.com/product-ibfr
• AliExpress: https://s.click.aliexpress.com/e/_Ddf0wMl