The DJI O4 Professional Air Unit is unbelievable, however one main draw back is its weight. At 33g, it’s not supreme for micro quads or builds that intention to remain below the 250g weight restrict.
That’s why the “bare” DJI O4 Professional has been one of the vital anticipated improve within the FPV pastime. A “bare O4 Professional” basically removes the unique housing and heatsink, changing them with a minimal aluminium bracket, lowering weight by 42%!
After taking a more in-depth have a look at the WalleFPV Bare O4 Professional, I’ve to say it’s extremely engineered. It’s clear lots of thought has gone into the design, and the extent of weight saving is spectacular. Nevertheless, it does introduce a number of trade-offs that it is best to contemplate earlier than utilizing it, which I’ll cowl on this overview.
New to the DJI FPV system?
The place to Purchase
Get the WalleFPV Bare O4 Professional Air Unit from:
You may as well simply purchase the improve package and modify your individual O4 Professional:
The package comes with these equipment
- M1.5 hex screwdriver
- Phillips screwdriver
- A bag of spare screws
- Two micro 5.8GHz antennas
If you are going to buy the total bare O4 Air Unit, it is going to additionally embody the unique housing and antennas. There may be additionally a 6-pin cable for connecting the Air Unit to the flight controller (not proven within the image). That is the usual cable that comes with the unique O4 Professional.
The Execs and Cons of Bare O4 Professional
Execs
Extremely light-weight
The unique DJI O4 Professional weighs round 33g, whereas the Bare O4 Professional is available in at slightly below 19g — a 14g discount. This considerably improves flight efficiency and effectivity of your FPV drone, making it supreme for micro quads, sub-250g builds, and long-range drones.
Drop-in compatibility
The Bare O4 Professional makes use of the identical mounting sample for each the digital camera and transmitter module as the unique air unit, making it appropriate with present frames and BNF drones. For present setups, it’s basically a plug-and-play improve.
Extra compact design
It’s barely smaller than the unique, permitting it to suit into tighter builds.
Similar performance
You get the very same options and efficiency as the unique DJI O4 Professional.
Cons
Cooling is a significant concern
From my testing, the Bare O4 Professional is rather more vulnerable to overheating with out ample airflow. It’s not supreme for enclosed frames or floor autos the place airflow is restricted.
Diminished sturdiness
Though the brackets are constituted of 6061 aerospace-grade aluminium (in accordance with WalleFPV), the PCB is much extra uncovered in comparison with the inventory housing. This makes it extra susceptible to crashes and environmental injury. You may need to contemplate including conformal coating for water resistance: https://oscarliang.com/waterproofing-drone-electronics/
ND filter compatibility
The unique DJI ND filters now not match. You’ll want to make use of WalleFPV’s customized ND filters. Alternatively, you’ll be able to reinstall the unique digital camera housing if you wish to maintain utilizing DJI filters.
Guarantee void
Modifying your DJI O4 Professional will void the DJI guarantee.
Measurement & Weight Mesurements and Comparability
Weight Breakdown
| Authentic O4 Professional | Bare O4 Professional | |
| Digicam Module (with cable) | 11.05g | 8.84g |
| Transmitter Module (no antennas) | 17.33g | 9.14g |
| Antennas | 4.16g | 0.87g |
| Whole Weight | 32.54g | 18.85g |
You may as well combine and match antennas or digital camera modules relying in your wants.
Dimensions
| Authentic O4 Professional | Bare O4 Professional | |
| Digicam cable size | 13cm | 15cm |
| Digicam width | 20mm | 20mm |
| Digicam mounting | 2x M2 Holes 16mm Aside | Similar |
| Transmitter measurement (WxLxH) | 33.5×33.5×13.3mm | 31.4×31.4x12mm |
| Transmitter mounting | 20x20mm & 25.5×25.5mm | Similar |
The mounting is basically equivalent, so it’s appropriate with present O4 Professional builds.
The longer 150mm cable is nice for 5-inch and long-range drones. A shorter 60mm cable can be out there, which is right for micro builds (2-inch and smaller).
Construct Particulars
Putting in the Bare O4 Professional is a breeze.
With authentic O4 Professional, my Flywoo Explorer weighs 166g:
With the Bare O4 Professional it now weighs solely 152g!
WalleFPV has gone to nice lengths to cut back weight—even utilizing aluminium screws to shave off each potential gram.
Left: Authentic housing screws; Proper: Bare O4 Professional Screws
Connector is held securely utilizing tiny Philip screws.
It’s this stage of consideration to element that makes the burden discount so spectacular, however it additionally highlights the trade-off: sturdiness and thermal efficiency take successful.
Overheat Testing
With the heatsink eliminated, we count on the Air Unit to overheat extra rapidly—so let’s take a look at it.
Take a look at Circumstances
- Ambient temperature: 20°C
- No airflow (indoor bench take a look at)
- Quad armed (Air Unit transmits at full energy 1200mW)
- Bitrate: 60Mbps
- VTX Onboard Recording: 4K 60fps
Outcomes
Authentic O4 Professional
- Overheat warning: 2 minutes
- Air Unit Shutdown: By no means (inside the 10-minute take a look at)
WalleFPV Bare O4 Professional
- Overheat warning: 40 seconds
- Air Unit Shutdown: 2 minutes
When the overheat warning seems, the Air Unit makes an attempt to cut back temperature by:
- Stopping onboard recording
- Dropping bitrate to 30–40Mbps
- Lowering transmission energy
If the temperature continues to rise, the Air Unit will finally shut down to forestall {hardware} injury—leading to full lack of video sign.
xxx overheat warning picture
Actual-World Implications
Bench testing represents the worst-case state of affairs as a result of there’s no airflow.
When you’re flying:
- Airflow considerably improves cooling
- Overheating is much less seemingly even with out heatsink
This has been confirmed with the bare DJI O3 Air Unit which I examined extensively. So long as there’s respectable airflow it shouldn’t be a difficulty.
Nevertheless, the outcomes clearly present that the Bare O4 Professional overheats a lot sooner because of the lack of a heatsink. Thermal administration turns into essential.
My Sensible Recommendation
From my testing, right here’s what I like to recommend:
- Use decrease VTX energy for short-range flying, or use Auto Energy
- Keep away from leaving the quad powered on the bottom for too lengthy, take off as quickly as potential after plugging within the battery
- In sizzling climate, all the time do a brief take a look at flight close by first, to verify your bare O4 can deal with it earlier than flying too distant
ND Filters
When you take away the unique digital camera housing, the inventory DJI ND filters are now not appropriate.
You’ll want WalleFPV’s devoted filter set:
Included Filters
Even if you happen to don’t use ND filters, I nonetheless advocate placing the UV filter on—it acts as a lens protector.
Additional Studying: Why ND filters are helpful to picture high quality: https://oscarliang.com/nd-filter-fpv/
Bare O4 Professional vs O4 Lite
With none modifications, the O4 Professional is clearly superior in picture high quality.
However issues change whenever you add a wide-angle lens to the O4 Lite. Try my overview right here: https://oscarliang.com/flywoo-o4-wide-angle-lens-new/
However relating to weight, the O4 Lite now not has the clear benefit over the Bare O4 Professional:
- O4 Lite + Extensive Angle lens: 15g
- Bare O4 Professional: 19g
For micro quads (just like the 1S Flywoo Firefly18), that 4g weight distinction nonetheless makes an enormous distinction.
And contemplate the worth distinction:
- O4 Lite + Extensive Angle lens: roughly $170
- Bare O4 Professional (DIY): roughly $260
With that stated, the O4 Lite merely can not match the O4 Professional digital camera relating to picture high quality, which includes a 1/1.3-inch sensor (higher dynamic vary and low gentle), 4K/120fps recording, a 155° ultra-wide-angle lens and 10-bit D-Log M colour mode—all essential options the O4 Lite digital camera lacks.
The best way to Improve
If you wish to convert your individual O4 Professional, you’ll be able to comply with this information: https://drive.google.com/file/d/1wmJ15Pm2PHmTLj2q3AZpOceW6Ngzxk88/view?usp=sharing
Conclusion
The WalleFPV Bare O4 Professional is strictly what many FPV pilots have been ready for—a technique to deliver the total efficiency of the DJI O4 Professional into light-weight builds.
The ~14g weight discount is very large, particularly for sub-250g micro drones and lengthy vary builds. And the engineering behind this package is genuinely spectacular.
Purchase the WalleFPV Bare O4 Professional Equipment right here:
Nevertheless, this comes with actual trade-offs:
- Considerably diminished cooling efficiency
- Elevated fragility
- Lack of compatibility with authentic ND filters
From my expertise, this improve makes probably the most sense if:
- You prioritize weight and efficiency
- You don’t crash quite a bit
- Your drone has respectable airflow to the air unit
In the event you’re constructing a high-performance light-weight quad with DJI O4 Professional, that is simply one of the vital impactful upgrades you may make. However if you happen to’re flying in sizzling climates, your drone has an enclosed body, otherwise you crash quite a bit, you’ll have to be additional cautious with this hack.