While indoor micro quads seem to be getting larger or more powerful, there’s a simultaneous shrinking of outdoor quads. We started looking for a 3″ quad so we could explore this area when Gearbest brought us the Helifar X140 PRO.

Helifar X140 PRO full kit

This ARF comes with a fairly standard array of parts.

What’s Included

  • Frame
  • Stack (FC, ESC, VTX)
  • Optional receiver (FrSky or AFHDS/Flysky)
  • Battery strap (installed)
  • 4 pairs 3041 propellers (8 total)
  • Dipole antenna
  • Small zip ties, heat shrink
  • An XT-60 connector (pre-installed connector is XT-30)
  • Warning card
  • Stickers

Parts Overview

I was surprised to find some of the components to be brand name parts. The included receiver is a FrSky XM+. The props have RK (RaceKraft) debossed into them. The XT60 connector is marked “Amass”. These all certainly appear to be genuine; even the original one-sheet manual for the XM+ is included in the box. We really hope that there’s a commitment by Helifar to keep using quality components like these—and not later on swap out inferior components like what happened with the Furibee Darkmax. If we find out later that the product is shipping with different components, we will definitely update this review. (If you find out before us, please let us know.)


The X140 PRO is framed by a carbon fiber base with removable arms in a stretched-X configuration, evoking the FLOSS 2 in positioning and mounting methods. Each arm is 4mm, with a chamfered edge. The top and bottom plates are each 2mm. Between the top and bottom plates are four standoffs, giving an interior height of 34mm. This is a generous height, and probably 10mm more than necessary. Two vertical carbon struts also span the horizontal plates, slotting into each with the purpose of providing a mounting point for the camera. These vertical plates are shaped like lightning bolts: a subtle detail to reward the observant, but without practical purpose. Holding the plates together are a dozen brass-colored screws, each with a rounded head. Like the FLOSS, the outer screws that only hold the arms in place terminate with a lock nut.

The camera mount provides an adjustable angle because its design is simply two screws against the carbon. You can expect the top edges of the frame and the props to be in view. I didn’t find either especially distracting when I was flying, but it’s a little distracting in the DVR.

Power/Flight Controller

The powertrain and flight controller are full of current-gen features: an F4 processor capable of 8K/8K, MPU6000 gyro, and Betaflight OSD. The 4-in-1 ESC portion of the stack handles 25A (30A burst) and is BLHeli_32, supporting up to DShot1200. This stack is soft-mounted with a set of grommets at the bottom and a set of rubber washers at the top. You get a voltage sensor, but not a current sensor. (I much prefer a mAh reading in addition to voltage when deciding when to land.) It also misses the ability to do Blackbox (except externally). The whole package has a 20mm mounting pattern and takes an input voltage of 2–4S.

Completing the powertrain are Skystars 1408 3800Kv motors following the now-common open-bottom design. All four motors use an M5 shaft with a CW-thread, so spare prop nuts are dime-a-dozen at any local hardware store and interchangeable with your larger motors. The bells are each held in place by an E-clip underneath. 3041 propellers are included for each, plus an extra full set.


The camera is a CCD. These days, many CMOS cameras can outperform the CCD, but there’s good reason why the Sony Super HAD II was the gold standard for a long time. Dynamic range, light/dark transition, color banding, saturation, and balance are all good. Not best-in-class, but more than enough for most types of flying. Paired with a 2.3mm lens gives a 145° field of view. This is more a matter of taste, but I found it to be a good match.

Helifar X140 PRO side view with antenna mount

The clearance between the prop arc and VTX antenna is only a few millimeters, but the stiffness of the SMA connector should prevent prop strikes.

The included antenna is, unsurprisingly, a sleeve dipole. It gets the job done, but almost anything else you have to put in its place will be an improvement. Because it’s mounted vertically from the side of the craft, you’ll have a harder time getting any distance between the antenna and the frame. At first I thought this would be an awful position, just a few mm from the prop arc. Instead, the antenna mount is stiff enough to prevent it from bending that far. Prop strike to the antenna should be rare.

The VTx is a 48-channel, the standard 40 plus L. Maximum power on the VTx is 200mW, which allows some exploring behind obstacles but no significant long-range flight. Minimum power is 0mW; turning on “Pit mode” appears to simply shut the transmitter off. If you require manually changing video channels, it’s the common system of short-press=channel, long-press=band, super-long-press=power. The LEDs show their setting in binary code (starting at zero) to save board space. Though the product description states an RP-SMA connector, mine was an SMA.


Rounding out the build is a combo board with two LEDs and a buzzer.

When buying the FrSky version, the included receiver is an XM+. This model lacks telemetry, so you can’t get many sensor readings and alarms back to your radio. Much of the data and functionality available through telemetry is duplicated through the OSD, so many pilots won’t miss it. I do, though; during races I like to shut the OSD off and allow my radio to relay any important warnings. Pilots like myself do have the option of buying the PNP version and supplying a receiver of their own choosing, but no wiring diagram appears to be available for the FC.

Setting Up

Helifar X140 PRO with XM+ Receiver hanging off the side

Out of the box the receiver is electrically connected, but not mounted at all. Bind it now, before you shove it inside and make it harder to get to.

When you buy an X140 PRO with an included receiver, What you get is the receiver physically connected to the correct port. It is not, however, mounted on the frame anywhere and is just hanging by the wires. We suggest you bind it now, before you find a place to put it. Ours came with a bit of double-sided tape already applied to the receiver. We stuck it to the underside of the top plate and used the zip-ties and heat shrink included for the purpose to route the antennas off the rear arms. There are plenty of cuts in the carbon if you prefer sticking them out the top plate.

We’ve documented the process of RC receiver antenna mounting in this post if you need some help!

On opening the box, you’re greeted with a yellow card that tells you to leave the firmware alone, only use a screwdriver set for a specific amount of torque, and other oddly specific restrictions. However, there’s an e-mail address to go to for questions. I went ahead and asked one, and got a response from someone the next day that was legitimately trying to help, seemed to actually understand the technical aspects of my question, and pointed me in a direction that answered it. If you’re already very experienced in quad building, I’m sure you can ignore this notice and go right on as you normally would. For those that aren’t, it could be a very important part of successful ownership. This kind of responsive support is a real rarity from overseas vendors and a step in the right direction in our opinion.


The X140 PRO is assembled in a way that keeps its internal components nicely protected. Motor wires are left bare across the arms, but it would take so much effort to push the prop blades down this far that prop strikes shouldn’t be a concern. The frame looks suitably strong, going with 4mm arms even though the dry weight is only 162g. Care has been taken to run the carbon parallel with each arm, maximizing strength across their weakest point, and chamfering should help prevent delamination. When the weight/inertial difference from a 5″ is factored in, the quad should take a fair beating before showing any structural problems.

Build Quality

Helifar X140 PRO with front right arm out of place

A missing screw caused the arms to shift out of place, and it took a while to find one with the right length.

The frame is a reasonably good design, but my front arms arrived slightly askew. I tracked this down to a missing screw and had to source my own to replace it. While the frame has individual arms, we don’t know where you could buy them if one breaks. As far as we’ve seen, you can only purchase the entire frame kit together.  Usually if a frame is popular, replacement parts tend to become available, so this is likely subject to change.

The biggest problem with my X140 PRO is the accelerometer. It won’t hold a calibration. At first, this caused the craft to simply not fly at all: I had to adjust the angle range to allow it to arm. Now that I’ve disabled it, the craft often lurches off to one side when any auto-leveling kicks in. The direction isn’t consistent. Pilots who exclusively fly in acro/rate mode may not even notice this issue, but pilots who rely on it would not be able to fly at all. I only occasionally use it, mostly for quick testing of configuration settings and if I need to do any line-of-sight. For my X140 PRO, I may simply disable it so I don’t encounter any unexpected, inconsistent, unpredictable behavior.

The included battery strap doesn’t hold well, so a battery will slip out easily. The strap is a little too long, and with smaller batteries, it could flop into the props during flight.  Sadly, this is par for the course on nearly any ARF/RTF quad we’ve seen.  We highly recommend replacing the included version with a quality battery strap.

Everything else on the quad appears to be in good shape, with no obvious issues. I’m impressed with the quality overall—but the attention to detail skipped the graphic design department: the box has the product title misspelled as “X140 RPO”.


If you take the Helifar out of the box, slap some props on, and go, you’ll have an okay time. We first tried it on 3S, and it had the flight feel of a big micro. That is, it’s a bit lethargic compared to your typical 5″ racer, and while it went where I wanted it to, it didn’t offer anything really special. But it was fun to zip around. Going to 4S exposed some pretty annoying oscillations. The stock tune is unsuitable here. It’s not just propwash; even punching out will induce wobble. You won’t be able to really enjoy a rig set up like this. Fortunately, this poor flight feel can be tuned out. We had the most success with a tune from AndyRC.

Pitch— P:36, I:50, D:14
Roll— P:33, I:90, D:14
Yaw— P:60, I:20

Once tuned up, this little craft was a blast. Now that the stability was there and the craft could handle 4S, it really showed its full potential. The tune improved flight feel on 3S as well, allowing more stable and locked-in flight. The difference between 3S and 4S became less important, so even 3S is a good choice for some freestyle. Now, and especially on 4S, I really felt like the craft handled closer to a full-size racer than a big micro. It’s very light, fast, and agile. It’s easy to whip it around and change directions. You don’t have to plan quite so far ahead when you want to hit a gate or a gap. In fact, gap-hitting felt almost effortless compared to a 5″ rig. This gives the pilot a lot of freedom to explore. I went flying on a dense forest path, and through the middle of tree canopy where I’d never dare to take my larger quads. I even had it out in 25mph winds during setup for an event, and it handled the wind as well as the larger rigs I flew that day. It was actually more fun to fly around the tight, technical course we had assembled. Lesser momentum (vs. a 5″) does make some freestyle maneuvers more difficult; the quad doesn’t hang in the air as long and give you as much time to complete your tricks.

In all, I was very impressed with the full capabilities of the craft, but you’ll only experience them if you get it tuned.

Modifications, Upgrades, and Replacements

The worthless battery strap should be replaced, so I went with a rubberized strap from RaceDayQuads. (If you buy a few batteries there, you can get this strap sent with your order for free.) It helped immensely, but installing it was frustrating. The entire stack has to be removed, and it’s all held in place by a single set of long bolts. Pull them out and tiny spacers, grommets, and washers go everywhere. If you’re not careful, you’ll be chasing them around the floor. Take note of the order they belong in before you pull them out, because each piece is a different size. Once installed, I had no more fear of a battery ejection.

If the FC/ESC failed, we might consider an upgrade to one with a current sensor, but it would be a lot to spend for a minor benefit while the existing one works.

Helifar X140 PRO side view showing available space inside the frame

There’s a fair amount of extra space in the frame, but the camera connector interferes with getting the stack any taller.

The Helifar’s predecessor, the Furibee X140, had enough extra space to stuff in a Runcam Split Mini to capture some HD footage. Unfortunately, the camera mount is closer to the stack on the 140 PRO. The Runcam won’t fit unless you construct a new camera mount. If you decide to do that, we don’t doubt the craft has enough power to handle carrying it.

If you’re just looking for replacement parts, most of the X140 can be purchased in pieces. We couldn’t find the unbranded camera, but any micro-size cameras should fit this frame. For batteries, we went with 650mAh 3S and 4S from RaceDayQuads. Tattu is always a safe choice, and CNHL is a good budget option as well. Like their larger batteries, these CNHL packs are underrated, so they’re larger and heavier but last longer than other brands.

helifar X140 PRO replacement parts:


It’s our understanding that Helifar is Gearbest’s new in-house brand. Perhaps Helifar represents a higher standard of product, including name-brand components in many cases. We’re happy to see the build quality in our Helifar X140 PRO and the name-brand parts in other Helifar products such as the FUUTON 2 sporting components from Holybro and Runcam. We really hope there’s a commitment to keeping this high standard over the life of the product. At ~$150-170 price point, (~$140 on sale) the quality really has to be there—fully built 5″ racers like the original Wizard X220 can be had for just $130 and kits can be found for just $99. In the 3″ space, that price is in line with similar offerings from strong brands like Emax.

Once you get a good tune on the X140 PRO, and if the durability proves out, the performance backs up the investment. It’s fast, light, agile, and a ton of fun to fly. The smaller size and weight opens up a lot of proximity flying possibilities, and it may even be competitive against 5″ racers on very technical courses. While the setup and build quality aren’t entirely without issues, they’re not overly complicated to fix. If you’re in the market for a 3″ and a little bit of tuning and tweaking doesn’t scare you, the Helifar X140 PRO will be a very enjoyable machine.

Interested in buying?  Gearbest gave us a few promo discounts you can use for the next few weeks.  You can get the helifar X140 PRO discounted to $140 using code RCDeal84.

Additional RC deals on other micro quads can be found here!


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