The Flywoo Explorer LR4 is arguably one of the best sub250 long-range FPV drones in 2025 when paired with the DJI O4 Pro Air Unit. But like any drone, it’s not perfect. There are a number of mods and upgrades that can significantly improve performance—such as installing a diversity receiver, optimizing antenna and GPS mounting, reducing weight, and a custom PID/filter tune.
Check out my full review of the Flywoo Explorer O4 Pro: https://oscarliang.com/flywoo-explorer-lr4-o4-pro/
Diversity Receiver Upgrade & Antenna Mounting
The stock receiver uses a single antenna mounted horizontally at the front under the frame. While this is fine for short-range flights, it’s far from ideal for long-range flying.
By upgrading to a true diversity receiver with two antennas, you can mount them vertically on both sides of the frame. This setup ensures that at least one antenna is in line of sight with your transmitter most of the time, resulting in a far more consistent and reliable radio link.
I’m using the RadioMaster RP4TD receiver, get it here:
It’s a bit too big to mount inside the frame, so I attached it underneath using a tiny 3D-printed TPU strap – I made it free to download here: https://www.thingiverse.com/thing:7062885
I also designed an antenna holder you can mount on the standoffs, it has a small 10-degree tilt so it remains vertical when cruising forward. I made the STL file free to download here: https://www.thingiverse.com/thing:7062886
This diversity receiver, along with the extra antenna, adds about 3g compared to the stock RX. However, for the improvement in signal reliability, I think it’s well worth it. If you don’t fly long range or are happy with the stock performance, the original receiver is still perfectly usable.
Optimizing GPS Mounting
Out of the box, the Explorer LR4 takes a long time to get a GPS 3D fix (Betaflight recommends at least 8 satellites for reliable GPS Rescue). Also, I rarely saw more than 20 satellites, and I suspect it’s due to Flywoo’s choice to mount the GPS under the VTX antennas, which introduces significant interference.
My solution? Move the GPS to the front of the drone.
In previous Explorer versions, this wasn’t an option because I had to mount a Naked GoPro up front. But thanks to the DJI O4 Pro’s onboard recording, I no longer need a separate camera, freeing up the perfect spot for GPS.
I designed a custom front-mounted GPS holder, free to download here: https://www.thingiverse.com/thing:7062882/
You can also safely remove the copper tape from the GPS module to save a bit more weight.
The improvement is substantial. After relocating the GPS:
- 3D fix (8 sats) in under 1 minute from a cold start
- Almost instant fix between battery swaps
- Maximum satellite count increased to 29
Switching GPS and Receiver UARTs
This mod is optional—but worth considering if you’re mounting the GPS and receiver like I did above, because the stock cables aren’t long enough. It makes more sense to swap the UART ports (i.e., move the receiver to UART5 and the GPS to UART2). This also keeps the wiring cleaner.
Important: The connector pinouts for UART2 and UART5 are different (why, Flywoo?!). You’ll need to re-pin the wires in the connectors. It’s a little annoying but not difficult.
Weight Reduction
I’ve optimized weight on dozens of BNF drones, and the Explorer was actually one of the most challenging – it’s already pretty well optimized, so there are not many places you can reduce weight. Also it’s such as lightweight drone, saving a few grams might feel underwhelming. But if you truly care about performance, a gram here and there adds up.
Warning: Removing hardware reduces crash resistance. Proceed at your own risk.
Here’s what I did:
- Removed arm guards and only use two screws per motor
- Removed the front second-row standoffs
- Removed copper tape on GPS wires (only if it’s relocated to the front like I did)
- Minimized cloth tape used on motor wires
- Used plastic nuts instead of metal on the FC/ESC stack
- Replaced screws (optional):
- Top/bottom plates: 5mm (was 6mm)
- Stack: 16mm (was 20mm)
- Motors: 5mm (was 6mm)
- Props: 6.5mm (was 7mm)
After performing all these modifications, I was able to shave 9g off my build. However, because I upgraded to a diversity antenna, it added 3g back. It might not sound much, but that’s 5% weight reduction on a quad that’s already extremely lightweight, and can potentially translate to another 20 to 30 seconds more flight time.
I think the DJI O4 Pro air unit has a huge potential for weight saving too. If we remove the case, heatsink and use lighter antenna alternatives, we could probably get rid of another 10g or more. However there’s currently no such “Naked O4 Pro” conversion kit exists (like what Flywoo did with the Naked O3 kit), but hopefully, some manufacturers would release one in the future.
You could consider removing the heat shrink on the battery for a ~2g saving. But it’s not recommended if you plan to travel by planes—batteries without labels might not pass security. Also, you could shorten motor wires which might save another 2–3g, but I didn’t do it this time.
As it stands, if you want to stay under 250g, the heaviest battery you can use is around 80g. The biggest battery I can find is the GNB 4S 850mAh LiHV 60C weighs in at ~73g. Get the it from AliExpress: https://s.click.aliexpress.com/e/_olJ1Gke
If you want to get the longest flight time, and weight isn’t an issue, 4S 18650 battery would be the top choice, 30+ minutes of flight time and 20km+ flight distance are possible. Ideally, you should build your own pack using high-quality cells. I recommend the Molicel P30B 18650 cells, which I’ve tested here: https://oscarliang.com/best-18650-li-ion-battery/#Results-and-Recommendations. You can also buy pre-built Li-ion packs, but they often use cheaper cells, here’s a list of options: https://oscarliang.com/li-ion-battery-long-range/#Buying-Ready-Made-Li-ion-Battery-Packs
PID & Filter Tuning
The Explorer flies decently out of the box—but I’m disappointed Flywoo didn’t even try to optimize the filters. That means there’s still room for improvement, especially after all the hardware changes we’ve made. Luckily, the Explorer has onboard flash for Blackbox logging, which makes filter tuning possible.
For your reference, I’ve shared my custom PID and filter tune on Patreon, along with GPS Rescue config, ports, power settings, rates, OSD layout, and more: https://www.patreon.com/posts/flywoo-explorer-131255399
Want to tune it yourself? Start here:
Using ND Filters
Get more cinematic footage by using ND filters. The official DJI ND filters don’t fit in the Flywoo Explorer LR4 frame, so I recommend low-profile ND filters such as the ones from BetaFPV—they’re also among the most affordable options available: https://oscarliang.com/betafpv-nd-filters-dji-o4-pro/
Learn how to use ND filters in this guide: https://oscarliang.com/nd-filter-fpv/
Other Minor Tweaks
- Disable LED_Strip in Betaflight’s Configuration tab (to reduce CPU load)
- Increase PID Loop Frequency from 2KHz to 4KHz (there’s enough CPU headroom)
- ESC Protocol: DShot300
- Current Sensor Scale: 450
- Voltage Sensor Scale: 111
Conclusion
With just a few thoughtful upgrades and modifications, you can take the already excellent Flywoo Explorer LR4 O4 and push it to the next level—improving signal reliability, GPS performance, flight performance and efficiency, all while staying under 250g.
If you are still debating whether to get the Explorer, check out my review here: https://oscarliang.com/flywoo-explorer-lr4-o4-pro/
Let me know what mods you’ve tried—or if there’s anything I missed!