The OasisFly25 from Sub250 is an exciting 2.5-inch FPV drone, equipped with the DJI O3 air unit and weighing under 250g, making it perfect for compact, freestyle flying. This drone is small enough to fit in your pocket yet packs plenty of power. It’s designed for those who love the thrill of freestyle flying in tight spaces or parks. In this review, I’ll walk you through my experience with the OasisFly25, including its specs, performance, flight characteristics, and whether it lives up to the hype.
Where to Buy
You can purchase the OasisFly25 from these vendors:
The drone is available with the DJI O3 system and a receiver installed, but there’s also a plug-and-play version if you want to use a different FPV system and receiver.
Inside the box, you’ll find the drone and two accessory boxes containing:
- Two sets of HQ 2.5×2.5×3 tri-bladed propellers
- Stickers and manuals
- Spare screws, standoffs, and a hex key
- 3D-printed camera holders (including one for a naked GoPro)
- USB-C adapter for the flight controller
Note that batteries are sold separately: https://oscarliang.com/product-fmf7
Spare propellers: https://s.click.aliexpress.com/e/_Dkaokyp
Specifications
- Flight controller: F7 with 35A ESC, which is impressive for a 2.5-inch drone
- Frame: Sub250 Oasis Frame, 135mm wheelbase, with 2mm top plate and 2.5mm bottom and arm thickness
- Flight controller: Redfox A3 F722 45A AIO
- Camera/VTX/Antenna: DJI O3 Air Unit
- Motors: Sub250 1404 4500kv
- Propellers: HQ2.5×2.5×3
- Receiver options: PNP, TBS Crossfire Nano, ELRS 2.4G
- Battery connector: XT30
- Recommended battery: 4S 530-730mAh LiPo (not included)
- Weight: 174g (without battery), 241g with 4S 720mAh
Build Quality and Design
The OasisFly25 boasts a sleek and durable design, combining carbon fiber and CNC aluminum for strength and stability. The simple, effective design means it’s easy to take apart when you need to repair it. The frame features replaceable arms, allowing you to swap out broken arms without needing to replace the entire frame. Spare frame parts are available on the Sub250 website.
Weighing 174g without a battery and 241g with a 720mAh 4S pack, the drone is perhaps a little heavy for a 2.5″ drone, but the build is very sturdy. The DJI O3 system provides a top-notch video feed, making this a great drone for recording high-quality footage.
The long frame body design means the propellers are not visible in the FPV camera’s view, so it doesn’t ruin your shot which is great. There’s enough room for you to place a secondary camera like a naked GoPro if you wish.
One minor downside is the absence of a USB port on the flight controller, requiring a special dongle to configure Betaflight. While not a deal-breaker, it adds some inconvenience if you need to make frequent changes.
The OasisFly25 frame can also accommodate the Walksnail Moonlight Camera and an analog setup, adding versatility.
The OasisFly25 has a robust construction and it can take a beating, but I’d still recommend getting extra props and arms just in case. I had a few crashes during testing, and the drone held up well, with only minor scratches on the motors and frame. The 3D-printed motor protectors also did their job, absorbing impact and keeping the motors in good shape.
Flight Performance
Now, let’s talk about how it flies.
Using the recommended 4S 720mAh LiHV battery brings the total weight to 241g, which is slightly heavy for a 2.5″ FPV drone. This setup won’t leave room for a naked GoPro if you want to stay under 250g, but the drone still performs incredibly well.
Right from the first takeoff, I was impressed by the drone’s power. Despite its small size, it offers excellent acceleration and stability, even in very windy conditions. It hovers effortlessly at 25% throttle, and with just a little throttle punch, it shoots up like a rocket. I was flying in 23MPH wind, the drone still felt locked in and stable, with very little propwash during aggressive maneuvers, and it wasn’t overly noisy.
Although the extra weight reduced some efficiency, the drone still handled well, offering about 5 minutes of aggressive flying. If you’re cruising, you can stretch the flight time to over 7 minutes. The OasisFly25 strikes a good balance between agility and efficiency.
With no propellers in view, you can capture clean footage whether you’re flying slowly or fast. The antenna performance was excellent, maintaining a strong signal throughout my flights.
This is probably one of the best 2.5″ quads with the DJI O3 I’ve flown for freestyle. It has that “flingability” you get from larger quads like a 5″, likely due to its heavier weight. It’s got the punch to throw around easily in the air, and inverted moves and dives are clean and smooth, without the uncontrollable washout seen in lighter micros. These qualities are key for a good freestyle quad. While it’s not as powerful as a 5″, it’s still responsive, punchy, and agile. Importantly, it’s quiet, so it won’t disturb people nearby.
When flying in tighter spaces like the woods, I was mostly working between the 20% to 30% throttle range, similar to a 5″, but it was much easier to maneuver due to its lighter weight and nimbleness compared to a larger quad.
I also tested smaller batteries, like a 4S 450mAh, but the flight time was almost halved compared to the 720mAh. While the lighter weight did improve flight performance, the reduced flight time didn’t justify the trade-off in my opinion. I’d recommend sticking with the 4S 720mAh from Sub250 for the best overall performance: https://oscarliang.com/product-fmf7
What Could Be Improved
I don’t much much negative to say about the Oasisfly25, quite happy about its design and performance really. The only thing is weight.
The frame’s durability adds extra weight, and while this contributes to its sturdiness, I would have preferred a lighter build for better efficiency and agility. However, the trade-off for durability is understandable.
You can reduce weight by removing the 3D-printed feet or using the Flywoo O3 naked kit to make the DJI O3 Air Unit 15+ grams lighter. Replacing the original O3 antenna with lightweight dipole antennas can also shave off a few grams, which is a reasonable choice for most users who won’t be flying long range with this model.
Another minor suggestion: making the battery lead slightly longer would reduce stress on the solder joints.
Finally, I’d love to see a bit more protection for the DJI O3 camera, a small protruded 3D printed piece attached to the front of the bottom plate would do a good job. For now I think it’s crucial to use an ND filter, or just a clear UV filter to protect the lens from scratching: https://oscarliang.com/flywoo-nd-filter-o3/
How to Setup
The flight controller comes pre-installed with Betaflight 4.4.3 (firmware target: SUB250REDFOXF722AIO). The ESC comes with BLHeli_32 firmware 32.9.
To set up this drone for first flight, here is what I did:
Binding ELRS Receiver
- The ExpressLRS receiver comes with ELRS 3.3.1 firmware, with the target Sub250 2400 RX.
- Power the receiver (via battery or USB) and wait for it to enter WiFi mode (indicated by a rapidly flashing LED).
- Connect to the ExpressLRS receiver’s WiFi network on your phone, open browser and go to 10.0.0.1, and enter your binding phrase.
- Follow other binding methods, see my detailed instructions here: https://oscarliang.com/bind-expresslrs-receivers/.
Binding DJI O3 Air Unit
Betaflight Setup
- Set your own rates.
- Configure switches for arm, angle, beeper, and turtle mode.
That’s it!
Final Thoughts: Is the Sub250 OasisFly25 Worth It?
Absolutely! The Sub250 OasisFly25 FPV drone offers fantastic performance in a compact, durable design. It’s fast, responsive, and excels at freestyle flying. Although it’s slightly heavier than ideal, the sheer fun and versatility it provides make up for the added weight.
For $396 with the DJI O3 system, the OasisFly25 is well-priced and perfect for both beginners and experienced pilots looking for a portable, sub-250g freestyle drone. You can purchase the OasisFly25 from these vendors:
If you’re in the market for a powerful and compact freestyle drone, the OasisFly25 is a solid choice that won’t disappoint.
