XK X251 Review

Quick facts:

Battery: Removable 950 mAh, 7.4 volt
Flight time: 12 min
Charge time: 75 min

Transmitter rates: 2 (programmable)
Transmitter compatibility: ?

Competitors: JJRC X1

Video review:


In December of 2015, I reviewed the JJRC X1 Shuttle, which had just made a big splash because it represented an unprecedented attempt at marrying the powerful brushless motors of the hobby grade multirotor world with the smaller price tag and greater ease-of-use of the toy grade multirotor world.

While it certainly seems to have been a commercial success, the idea didn’t come fully formed and the X1 – while overall competent – did come with some teething problems, leaving the door open for someone else to swoop in and at least try to do the same thing only better.

It’s now half a year later and exactly this has happened. The X251, comparable in both size and price, is being touted as relative newcomer XK’s answer to the X1. I remember reading somewhere that XK is a more luxurious (as in less cheap) and enthusiasts oriented off-shot of WLToys. Regardless, they have a decent track record and seem to put care into the models they release. Let’s see if it’s true in this case as well!

The XK X251 arrives fully assembled (even propellers mounted!) in a very large box for a quadcopter not as big as you may think. Albeit the same size class as the JJRC X1 (250, indicating the longest motor-to-motor distance in millimeters), it also sports smaller – though still brushless – motors, shorter propellers (5 as opposed to 6 inches) and an overall slimmer design, which – taken together – gives off an impression of a smaller aircraft.

Because of said factors it’s also considerably lighter, weighing in at a little over 200 grams (of which the battery makes up around 40) as opposed to the X1’s closer to 300. I’m not an expert on this FAA drone registration business (as you can probably tell from my accent, I’m not based in the US), but I believe this means there’s no paperwork required!

No matter how you slice it, it’s hard not seeing the X251 as a response to the successful JJRC X1. XK have even made sure to address some of the most common criticisms of its competitor. One such example is the LEDs. The X1 had poor lights and flying it during nighttime was pretty much a no-go. With well-placed and color-coded LEDs on each motor pod, this is not a problem with the X251. There’s even an extra, dual-color LED in the back for indicating the status of the aircraft, like which mode it’s in and if the battery’s running low.

Another example of the X251 exceling at a point the X1 was kind of disappointing on is the transmitter. While I’m willing to go as far as calling the X1’s transmitter serviceable, others carry a more bluntly negative opinion. Let’s agree it wasn’t all it could’ve been! Now this is your typical toy grade transmitter, this is a hobby grade style but functionality-wise still toy grade transmitter and this… is the transmitter for the X251!

This borderline hobby grade “bad boy” feels well-built, has excellent sticks with good travel and resolution as well as a big back-lit display. The equally sturdy switches are used to switch between the two rates (high and low), the two modes (“6G” and “3G”, more on this later) and to cut the throttle (a much needed failsafe when dealing with these brushless multirotors). The jog-wheel and buttons around the display may be used to tweak the rates in various ways, meaning unlike toy grade multirotors you’re not stuck with the pre-programed rates but can customize a large part of the flight characteristics to your hearts content.

This was really just an overview, I could easily have done a full-length video on the transmitter alone!

While the transmitter itself is a huge positive, it also segues into one of the negatives about the XK X251: the documentation – or rather lack thereof. I wasn’t as unlucky as some early adopters who apparently were sent Chinese-only instruction manuals, but the translated version still leaves a lot to be desired: Dubious spelling and phrasing are to be expected, but the real issue here is that it’s absolutely all over the place in terms of its level of detail. You’ll find surprisingly intricate information like freaking schematics, at the same time basic stuff like how the different modes function or how to work the transmitter menus are either practically or completely absent.

Having to spend the first time of your quadcopter ownership searching the web for instructions on how to get going not only makes for a poor customer experience but is also – I suspect – a strong contributing factor to why manufacturers like XK never really seem to break into the mainstream.

While it might not look it at first glance, the X251 – with its carbon fiber arms, thick canopy and seemingly thought-out construction – feels sturdy, which – at least in theory – should give it good durability. This – at this point – seems verified by many online testimonies – both in written and in video form – of the aircraft surviving serious crashes. I even experienced one of these myself when I misjudged the distance and flew it straight into a tree, but was pleasantly surprised when it came out pretty much completely unscathed!

Should something break though (or you’re looking to trick out your aircraft), you may have to deal with the fact that the X251 unfortunately isn’t as exemplary as the X1 when it comes to using standard parts and specs.

As you can see, the brushless motors have a size indication of 1307, which is smaller and – from what I gather – less widely used than the X1’s 1806. That they’re smaller isn’t the problem: There are so many factors that play into a multirotors feeling of power (like weight, propeller size and pitch as well as overall configuration), that motor size alone doesn’t say a lot. The problem is that these motors have a shorter shaft, meaning many standard propellers simply won’t fit right.

Now this isn’t as serious as it could have been: There’s certainly nothing wrong with the included props and their dimensions should cater to most tastes, but you suspect XK have done it only to deter people from using anything but their “official” spare parts.

This suspicion continues to the 2 cells-in-series, 950 mAh LiPo, which lacks the JST connector standard on multi-cell RC batteries, instead using the balance plug for both charging and discharging. Unmodified – this complicates charging the stock battery with a proper hobby charger (as it assumes both connectors) and standard replacement batteries with the included charger (as it assumes overcurrent protection to prevent overcharging). Sure if you know what you’re doing you can get around a lot of this, but it’s further proof of XK’s intent to try to limit their customers to proprietary accessories.

Looking past this though, XK must have gotten some proportions just right, because the flight times on the stock battery are great: 12+ minutes with a moderately long LVC warning, while charging with the included wall charger (which I’m sure you recognize if you own a multi-cell toy grade multirotor) clocks in at a tolerable 75 minutes.

Apart from the accessories already mentioned (transmitter, battery, charger and instruction manual), the X251 also comes with a set of spare propellers and a tool for loosening and tightening the prop caps so you can replace said props.

Flight-wise the XK X251 – in my opinion – just straight-up delivers. The overall impression is that of a stable and – at least in part thanks to the transmitter – precise quadcopter that’s also dependable, by which I mean it behaves as you expect it to without any quirks or issues to be aware of. Because of their power with potential to do real damage to both people and property, I generally don’t think brushless quadcopters should be recommended to complete beginners, but given the just mentioned characteristics the X251 at least makes for an ideal step up from brushed quadcopters.

Of course one of the advantages of brushless over brushed motors is power. How does the X251 utilize this? As evidenced by the throttle punches you can pull off, the power is definitely there, though the rates are – out-of-the-box – pretty moderately set. As mentioned earlier though, the transmitter is programmable, allowing the rates to be tweaked to match your flight style – within limits.

For the expert flyers out there, the X251 used to have a rate mode accessed via the 6G/3G switch shown earlier. In “Rate” (also called “Acro” or “Manual”) mode there is no self-leveling and the pitch/roll stick controls the rate of rotation (hence the name!). This in contrast to the “Angle” (also called “Self-level”) mode most of us with a toy grade multirotor background are used to, where there is always self-leveling and the pitch/roll stick controls the angle (hence that name!).

I was pretty excited about this as “Rate” mode – while difficult to master – opens up a whole range of stunts and maneuvers not otherwise possible to pull off, but sadly – for whatever reason – XK decided to remove it from the X251 soon after release. If you buy an X251 today, like me you’re most likely going to get the revised version instead, where “Rate” has been replaced with “Rattitude”. In “Rattitude” (also called “Horizon”) mode, the pitch/roll stick towards its endpoints controls the rate of rotation but near the center offers stabilization. This hybrid is far less common and understandably so as it feels like a compromise that fully satisfies neither beginners nor experts. The only thing it successfully brings to the table is the possibility to pull off reasonably tight manual flips.

Keep in mind that this debacle, which I see more as a missed positive than a negative, is XK’s only real trip-up in the flight department. Apart from the satisfying flight characteristics, there’s also the impressive flight times, solid transmitter and – thanks to the use of the Futaba protocol – excellent range.

So in conclusion, which is the better choice: The XK X251 Whirlwind or the JJRC X1 Shuttle? Before handing out any verdict, it should be noted that both are overall competent models, offer some pretty impressive value for money and should make for solid choices if you’re looking to dip your toe into the world of brushless multirotors. There is certainly more that unites them than sets them apart!

That being said, I think the XK X251 comes out on top. Both models fly well, but with its outstanding transmitter, superior lights and programmable rates the X251 just comes off as the more complete, well-rounded package. The poor manual is a bummer for sure, especially seeing as it’s being targeted at the entry level crowd. So is the missing rate mode, but then that isn’t part of the X1’s offering either.

There are some reasons you may still want to consider the X1 though: Out of the box, the X1 feels like the sportier of the two and even given the X251’s programmable rates, I believe there are still some results you can’t quite achieve. Also, by sticking closer to standard parts and measurements, the X1 is bound to be the more easily modifiable and repairable of the two.
Choose wisely!

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