When I was window shopping for a new 3-inch freestyle drone, I came across the RATE S30 Pro and immediately wondered how this drone could be so cheap when the specs look great on paper. So I decided to pick one up for a review. I’ll also be comparing it to my current favourite, the Deepspace Seeker3, to see which one is the better 3-inch FPV drone when paired with the DJI O4 Pro Air Unit.
Check out my 3-inch FPV drone comparison with the O4 Air Unit here: https://oscarliang.com/best-3inch-micro-fpv-drone/
Where to Buy
Get the RATE S30 Pro FPV drone from Banggood: https://oscarliang.com/product-nomu
Comes with
- 2 battery straps (15cm and 20cm long)
- Mounting hardware for various FPV setups (Analog, DJI O3, Vista, DJI O4 Pro)
- Zip ties
- 1 set of propellers (4 total)
- 2 screwdriver bits
Specifications
- Frame: S30 Pro Freestyle FPV Racing Frame
- Wheelbase: 139mm
- Flight Controller: RATE F405 Mini
- ESC: RATE 30A Mini
- Motors: RT 1505 4300KV
- Propellers: HQ T3x3x3 / Gemfan (1 pack)
- Dimensions: 128 × 38 × 42mm (L × W × H)
- Receiver Options: None / RATE ELRS 2.4G / TBS Nano RX (optional)
- Input Voltage: 4S
- Camera Mounting: Supports 14mm, 19mm, and 20mm wide cameras
- VTX Mounting: Compatible with 20×20mm and 25×25mm mounting patterns
- Weight (My Measurements)
- Without FPV setup or battery: 135g
- With DJI O4 Pro, no battery: 172g
- With DJI O4 Pro + Sub250 4S 720mAh LiHV: 239g
- With DJI O4 Pro + BetaFPV LAVA 4S 850mAh LiPo: 266g
Installing the DJI O4 Pro Air Unit
The RATE S30 Pro is sold without an FPV system installed, so you’ll need to add your own. The installation process was slightly more involved than I expected. There’s no printed manual included—there is an online manual, but it’s only two pages, entirely in Chinese, and only 2 pictures, so it’s not very helpful.
For experienced builders, this shouldn’t be a major issue, but it’s not the most beginner-friendly.
All the screws are neatly organized in labeled bags, but again, the labels are in Chinese only.
Here’s a quick overview of how I installed the DJI O4 Pro Air Unit:
Route the camera cable underneath the ESC first.
To mount the camera, use the included screwdriver bit (a normal screwdriver won’t work because the motor is in the way).
Mount the antenna and connect the camera to the air unit.
To connect the air unit to the flight controller, you’ll need to remove the FC first, as the connector is located underneath the board.
You can leave the SBUS wire connected. It’s wired to UART3 (R3) on the FC, which isn’t used by default, so it won’t cause any issues. However, if you plan to use UART3 for another peripheral, make sure to remove the SBUS wire from the harness to avoid conflicts.
The O4 Pro Air Unit connects to UART4, and it’s already configured in Betaflight. You shouldn’t need to change any settings — it should work right away after installation.
Finally, zip-tie all the wires securely to prevent them from getting chopped by the propellers.
Stick the receiver on top of the air unit—the receiver comes with pre-applied double-sided tape, which is a nice touch.
The beeper is designed to be sandwiched between the top plate and one of the rear standoffs, as shown.
Design
This is my personal favourite type of traditional freestyle drone design—nothing flashy or over-engineered, just practical and simple. It’s easy to work with, easy to repair, and easy to maintain.
One of the things that caught my eye was its low weight. Without a battery, it weighs only 172g including the DJI O4 Pro, which is over 6g lighter than the Seeker3. It would be even lighter without those plastic side panels – which I am not a fan of.
They’re designed to be openable like a door, but in practice they are extremely difficult to release. Because they clip onto the FC stack’s nylon nuts, pulling too hard can rip the nylon nut off along with the panel, which is frustrating.
You can remove the panels entirely, and doing so would save a few grams. However, they indeed do a good job of keeping dirt and debris out of the electronics—as you can see on my quad after a few flights.
Soldering quality looks good overall.
The 3D-printed antenna mounts are well designed for both the DJI O4 Pro and the ELRS receiver.
The camera is quite exposed, so I’d recommend using an ND filter or UV filter to protect the O4 camera lens.
Flight Performance
There’s no GPS onboard, so I can’t say exactly what the top speed is. Although the S30 Pro is lightweight and runs 1505 motors, when flying it back-to-back with the Seeker3, the Seeker3 does feel slightly faster and more punchy.
That doesn’t mean the S30 Pro is slow—it’s still a powerful and agile freestyle beast. In fact, it’s more efficient than the Seeker3, delivering over 30 seconds of extra flight time on average. It also feels more forgiving and easier to handle, and it’s slightly quieter as well.
One common criticism online about the S30 is that the stock PID and filter tuning is poor, but I didn’t find that to be true at all. The factory tune feels smooth and locked-in, with very little propwash. I don’t think it really needs any tuning changes—it’s good enough as-is for what this drone is designed to do.
I think lighter batteries suit the S30 Pro best. The Sub250 4S 750mAh LiHV (get it here: https://oscarliang.com/product-fmf7) is an excellent match—it keeps the quad under the 250g weight limit and makes it feel much more nimble. A 4S 850mAh battery is also a solid choice if you prefer longer flight time of up to 7–8 minutes (if only cruising). You can still freestyle with it, but lighter batteries are way more fun and still give you almost 5 minutes of aggressive freestyle flying.
The current sensor appears to be fairly accurate, and I didn’t need to make any adjustments.
How to Setup
FC / ESC / RX Firmware:
- Flight Controller Board Target: RATEF405_V3 (preloaded with Betaflight 4.5.2). Original CLI Diff available here.
- ESC Firmware: AM32 (RATE_V203_01 Version 2.18)
- Receiver: Rate 2.4GHz RX running ExpressLRS v3.5
Setup Instructions:
Conclusion: S30 Pro or Seeker3?
For $120, I can confidently recommend the RATE S30 Pro. It’s such as great deal.
It’s not the most beginner-friendly due to the lack of an English manual, but for experienced pilots, that shouldn’t be a dealbreaker. Other drawbacks include the lack of GPS and slightly lower power compared to the Seeker3. However, it’s significantly cheaper while still delivering very respectable freestyle performance with an excellent factory tune. The included accessories are generous and support a wide range of FPV setups.
RATE has hinted at long-range potential by recommending a 4S 3000mAh Li-ion pack for this drone. With its efficient motors, I’m sure it could achieve very long flight times—but I wouldn’t attempt that without adding a GPS module first.
The Seeker3 remains the premium option, offering better performance and a more complete set of features out of the box. The RATE S30 Pro, however, is an excellent budget alternative for pilots who want a capable, fun-to-fly freestyle drone without spending a lot.
