Want something compact yet has decent flight performance? Check out the GEPRC Smart 35 – a 3.5″ freestyle FPV drone. It’s well tuned and flies great out of the box, if you don’t want to build it from scratch and tune it, you have to check out the Smart35.
Where to Buy?
There are 3 receiver options: PNP (no receiver), Frsky R-XSR and TBS Crossfire Nano. There are two versions based on what FPV system you want to run. I will be reviewing the DJI HD version.
DJI HD Version (Caddx Nebula Nano + Vista): https://oscarliang.com/product-9up7
Analog Version (Caddx Ratel V2 + 600mW VTX): https://oscarliang.com/product-9z7t
You might also want to get some spare props as it only comes with one set:
The GEPRC Smart 35 comes with the following accessories in the box.
Should You Get the GEPRC Smart 35?
Just like the GEPRC Rocket, I am super happy with the PID/Filter tune of the Smart 35. It just flies so damn well and I can’t recommend it enough.
And let me explain what the GEPRC Smart 35 FPV drone is designed for.
This is the first time I tried a 3.5″ drone. Normally there are either 3″ or 4″, so you can imagine the performance is in between these two more common sizes. Comparing to a 3″, it’s pretty hard to spot the difference until you put them side by side.
4″ is also a popular size for sub 250-gram builds (weight limit for registration in some countries), but normally it would have to use skinny frames and under-powered motors, especially with the extra weight from an HD camera on top.
3.5″ aims to strike for that perfect balance between durability, weight and performance, to offer the best possible handling while staying under 250g all-up-weight.
Notice there’s a power cable already soldered to the FC, and it comes with a 3D printed mount. Both of them are for the new GEPRC Naked GoPro 8. Of course you can also use other HD cameras of your choice.
The Naked GoPro weighs only 27g, this quad can totally handle it like a champ. With the built-in stabilization or using Reelsteady, you can get some amazing cinematic footage.
GEPRC never disappoints when it comes to factory PID and filter tuning. My good experience started with the GEPRC Rocket and it continues with the Smart 35. It flies like it’s on rail and is free of jello even when doing punch outs. Little to none when it comes to bounce backs and prop wash, just amazing tune. If you don’t know much about building and tuning, the Smart 35 will save you many headaches. Check out my flight here:
In terms of flight performance, the GEPRC Smart 35 feels like the Flywoo Explorer 4″ on steroid. Of course, it’s not as energy efficient, but it’s more powerful, nimble and aggressive with those 1404 3850KV motors.
Higher KV and smaller props means RPM is much higher, hence the quad feels faster and more responsive. It’s definitely more suited for freestyle and acrobatic style flying. Yet if you take it easy, a relax cruise flight can still give you 7 – 8 minutes of flight time on 4S 850mAh.
Those 3.5″ props are Emax 3528 triblade, they are the same props used in the Babyhawk II HD.
If you find 5″ quad too scary to fly in your busy local parks, this 3.5″ might be a better option. It’s quieter and handles very much just like a 5″.
Closer Look at the GEPRC Smart 35
- GEP-F411-35A AIO FC
- MCU: STM32F411
- MPU6000 Gyro
- BLHeli_S 35A 4in1 ESC
- Input Voltage: 4S
- Caddx Vista VTX
- FPV Camera: Caddx Nebula Nano V2
- VTX Antenna: Momoda 5.8g UFL LHCP
- Motors: GR1404-3850KV
- Props: EMAX 3.5*2.8*3 (3528×3)
- Weight without LiPo: 150g
The arms are 4mm thick, I crashed and fell on concrete a few times and it held up well. But if you are still looking for more strength, there are carbon fibre braces included in the kit that you can add to the arms.
It’s a compact frame, so you will see some props and top canopy in the FPV camera view, but it’s not the end of the world.
The Vista is mounted under the top plate, and not on the bottom plate which is an interesting idea.
You have these plastic covers on each arm to protect the motors wires from getting chopped by bent prop in crashes.
The FPV camera doesn’t extrude from the frame and is well protected by the front standoffs. If yours came extruding from the frame, you can push the camera back by loosening the side screws in the camera plates.
Here’s the 3D printed TPU antenna mount. I am a little concerned about the RX antenna getting chopped by spinning props, something you should pay attention to. It hasn’t caused me any problems yet, but it needs a better solution.
There’s no strain relief on the battery lead (XT30), you should probably zip tie it to one of the rear standoffs. The Smart 35 is equipped with GEPRC’s own LHCP antenna for the Caddx Vista VTX.
Finally, I wish it had a beeper which can help you find the model more easily after crashing. ESC beacon is setup out of the box, which uses motors as beeper but they are not quite as loud.
Battery and Weight
I recommend running 4S 850mAh LiPo batteries on the Smart 35, and without using an HD camera you should be able to stay under 250g comfortably. Here’s my battery recommendation.
However, with an HD camera like the Naked GoPro Hero 8, you probably want to use a smaller battery if you want to hit that 250gr weight target, e.g. a 4S 650mAh.
The GEPRC Smart 35 is not really designed for long range. With that powerful motor and prop setup, it can be quite power hungry if you fly aggressively. Flight time is not too bad though, I am getting 4-5 mins on 4S 650mAh, and 6min on 4S 850mAh.
How to Setup
Stock CLI dump can be found here.
- Board: GEPR/GEPRC_F411_AIO(STM32F411), loaded with Betaflight version 4.2.3
- BLHeli_S 16.70 Firmware (G-H-30)
Bind Crossfire receiver (you will have to push the bind button on the receiver first), then check in Betaflight Configurator receiver tab if you get response from stick movement.
Check if the motors are running correctly in the motors tab. DO NOT mount props while testing motors on the bench. Use a smoke stopper if you have one. For some strange reason, motor #1 in my quad spins the opposite direction and needs to be corrected in BLHeli Configurator.
- In Modes, assign switches to Arm / Beeper / Flip over after crash
- Disable RX_LOST in DShot Beacon in Configuration tab to avoid motor overheat when you crash and lost signal
- Setup OSD elements
Activate and update Caddx Vista. Do this with a fan blowing as it can take several minutes and you don’t want the VTX to overheat. Stock firmware is 1.05 and you want latest version 1.06 to use 50Mbps mode.
Finally bind it to to DJI FPV Goggles.
You can now mount the props and get ready for first flight!