Walkera QR X350 Pro (Long Term Review)

In my earlier review of the Walkera QR X350 Pro, I had given my initial impressions of Walkera’s entry-level 350-size quadcopter. Most of it were good but that was nearly three months ago and since then I’ve had some really interesting experiences with it, culminating in a spectacular crash a few days ago which resulted in a ruined quad and close to $300 in damages.

Suffice to say, my experience of owning the X350 Pro has not been all rosy and although my initial impressions of it were generally good, three months of flying it has revealed flaws that were not obvious in the beginning.

Poor Implementation of APM AutoPilot

For a start, the APM-based Devo M flight controller that comes with the X350 Pro appears to be a botched up version of the original APM by ArduPilot. My initial problems with the X350 Pro centered around its erratic flight behavior which usually happens after I tweaked around with some simple parameters in Mission Planner such as the RTL height. After hours of researching I found out that I wasn’t alone and that other X350 Pro owners have also experienced the same problems.

My X350 Pro during happier times.

My X350 Pro during happier times

In case you are facing the same issue with erratic flight behavior after tweaking around in Mission Planner, the only way to restore your X350 Pro back to factory settings is to load the original parameter list which is available on the RCGroups forum. To restore the original list, connect your X350 Pro to Mission Planner (without connecting the battery). Click on the Config/Tuning tab in Mission Planner and select “Full Parameter List”. In the Full Parameter List screen, click on “Load” to load the original parameter file. Parameters in the original list that differs from your current parameters will be highlighted in green. This gives you a visual idea of how different your list is from the original one. Once loaded, click on “Write” to overwrite the parameters in your X350 Pro. Once restored your X350 Pro should fly properly unless there is some hardware damage or calibration problem.

My badly damaged Devo M flight controller. The Devo M is the main culprit of many X350 Pro crashes apart from pilot error.

My badly damaged Devo M flight controller. The Devo M is the main culprit of many X350 Pro crashes apart from pilot error.

The general advice now for any X350 Pro owner is this — use Mission Planner only for waypoint navigation and nothing else, unless you are an ArduPilot developer and know exactly what you’re doing. Any attempt to tweak around with your quad’s parameters, even basic ones, will result in a X350 Pro that won’t fly properly. It seems the cause of this problem is how Walkera implemented the APM-based Devo M flight controller. Some APM features have either been locked or improperly tweaked around with, which means the Devo M flight controller does not behave like other flight controllers that make use of the APM Autopilot Suite.

Low Voltage Cutoff — the X350 Pro’s Own Suicide Feature

Perhaps the most critical flaw in the X350 Pro is its Low Voltage Cutoff (LVC) feature which has been blamed by countless X350 Pro owners for causing their quads to crash or drop very fast from the air. Ironically, the LVC feature was intended to prevent damage by preventing batteries from over-discharging. Both the X350 and X350 Pro are known to crash due to issues with the LVC.

So how does the LVC cause crashes? When flying your X350 Pro, the voltage in your battery will occasionally drop to 10.75V or less. This is normal and usually last only a split second but when the flight controller detects this drop in voltage, it will attempt to cut off power to the motors in an attempt to save the battery from over-discharging. What happens when the LVC kicks in during a flight? You guessed that right — a plumetting X350 Pro.

In my case, I learnt my LVC lesson the hard way.

With that said, you might be wondering why did Walkera incorporate LVC in the X350 Pro anyway since it can potentially cause the quad to drop like a rock from high altitude. Surely, choosing to preserve the battery at the expense of destroying the entire quad just simply doesn’t make sense.

Well, LVC is a safety feature meant to save RC airplanes from crashing when battery power runs low. When a battery is depleted, power to both the propeller and steering servos gets cut off simultaneously, resulting in a crash. With LVC, the plane’s flight controller will shut off the propeller first in order to save some power for the steering servos. This allows the pilot to save the plane by performing a “dead-stick landing” —  a type of forced landing when an aircraft loses all of its propulsive power and is forced to land.

In an RC airplane, LVC is intended to protect both the airplane and battery from damage. While LVC is an essential safety feature in RC airplanes, it simply has no place in a quadcopter which uses its propellers for both propulsion and steering. The APM AutoPilot was designed to be used by a variety of unmanned vehicles, including RC airplanes which rely on the LVC feature. Since the X350 makes use of the APM AutoPilot, someone at Walkera probably forgot to turn LVC off.

Due to this reason, X350s have been crashing so often that owners eventually found out the cause and fixed it themselves. It’s puzzling why Walkera hasn’t solved the LVC issue in the X350 Pro although the problem has been plaguing the line since the earlier X350.

However, if you’re a proud owner of a X350 Pro, it’s not the end of the world for your quad. As I mentioned just now, there is a DIY solution for disabling LVC. You can read about it at the RCGroups forum here. If you don’t have the time to read, this short video explains the LVC mod in about 5 minutes.

If you’ve just bought a new X350 Pro, my advice is never fly without disabling the LVC unless you enjoy seeing your quad do heart-stopping kamikaze dives. However, once you have disabled LVC, you will have no way of knowing how much power your battery has if you don’t have live telemetry readings from your quad when flying. Remember that draining your 11.1V 3-cell 5200mAh battery to 10V or less can cause some serious damage. An effective and affordable way to deal with this risk is to install a battery voltage checker with buzzer.

I’d recommend a Integy C23212 voltage checker which costs less than $5 on Amazon with shipping. The Integy C23212 not only shows your battery’s voltage, it can also be used to check the voltage on each battery cell and has a buzzer to warn you if the voltage drops below a certain value (this lower limit is programmable). Just plug in the voltage checker into the balance port of your battery for it to work.

The Integy C23212 Lipo Voltage Checker can help cure "kamikazelitis" in your X350 Pro.

The Integy C23212 Lipo Voltage Checker can help cure “kamikazelitis” in your X350 Pro.

Another essential item to have when flying your X350 Pro is a stopwatch. Bear in mind that you may not always hear the buzzer on your voltage checker, especially when your quad is some distance away. This is why having a stopwatch or timer to time your flights is important. A X350 Pro without any extra payload has a flight time of about 25 minutes. A fully loaded X350 Pro with camera and gimbal will fly for about 15 minutes so having a timer will give you a rough idea when it is time to land before your battery gets damaged from being over-discharged.

Camera Gimbal System

My X350 Pro’s epic crash from 60m in the air resulted in a badly mangled G-2D gimbal. This wasn’t surprising since it landed on hard tarmac. The impact had caused the Devo M flight controller to be pancaked, apart from crushing the plastic body like an egg shell and causing damage to various other parts such as the power distribution board and landing skids. Surprisingly, the iLook+ camera survived the crash intact with only a small dent at the bottom. I had installed a lens protector which got shattered but managed to protect the front element of the lens from scratches or getting cracked. The iLook+ is still capable of taking videos (and transmitting video), still photos and audio and record them on a memory card. Kudos to Walkera for building such a sturdy camera.

Conclusion

Without the LVC issue and botched implementation of the APM AutoPilot, the X350 Pro is actually a nice and reliable quadcopter to own and fly. It’s a shame that Walkera had to ship the X350 Pro with these critical flaws and leaving Walkera fans to fend for themselves. With such flaws, the X350 Pro is certainly in no position to challenge the DJI Phantom 2 which is known to be more reliable. Disabling the LVC and installing a voltage checker in their products shouldn’t be a costly move but exactly why Walkera hasn’t done this with the X350 Pro is simply beyond my understanding.

What's left of my X350 Pro's plastic body. I plan to salvage the usable parts to build a 250-size quad soon.

What’s left of my X350 Pro’s plastic body. I plan to salvage the usable parts to build a 250-size quad soon.

I hope Walkera has been listening to the problems faced by X350 Pro owners and will not repeat the same mistakes on the upcoming X350 Ultimate which is due to be released soon. If you already own a X350 Pro or plan to get one soon, there is no reason to panic or cancel your order. Just remember to disable the LVC and not mess around with parameters in Mission Planner and your X350 Pro will fly just fine.



Adrin Sham

Adrin Sham is a designer and photographer turned drone enthusiast. Since buying a drone for aerial photography some years ago, he has since developed a passion for UAVs and all things related.

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23 Responses

  1. Eben says:

    How do one fly missions as auto mode is not one of the default factory settings? Or will it be ok to set one of the flight modes for that and one of the channels for rtl? Just had the same power lost crash, whish I had known about this issue

    • admin says:

      Sorry to hear about your crash Eben. I hope the damage was minimal. Auto mode is not set in your transmitter’s factory settings. You need to use Mission Planner to assign a switch on your transmitter to turn it on.

      For Auto mode, I’d recommend you use a switch that has not been previously assigned to anything. On my Devo F12E, I use the Elev D/R switch to turn on Auto Mode.

      Hope that helps

  2. Eben says:

    Thanks for reply. The damage was not too bad. Body cracked and one of the motors struglle to turn. I have the devo 10 and have the fmod and ale d/r switch nicely setup to switch nicely between all the 6 flight modes (Although for some reasen mode 3 and 4 seems to be stuck on alt hold no matter what the selection is in mission planner) Just 2 questions about the lvc problem, can it happen with a fresh fully charged battery? Had it happened with about 3 minutes flying time on the battery and is still reading 12.18v. Will disabling this lvc as per suggestion prevent the osd that is connected to the module from giving the correct battery voltage? What about the rtl setting for voltage below 10.75? Will that also be triggered when the voltage dip below that briefly?

    Thanks so much for all the advice

    • admin says:

      I’ve had the LVC problem kick in after just flying for about 3 to 5 minutes on a fully charged battery. It has happened when the battery is still over 12V. Usually the motors will lose power drastically but still continue to spin, though not fast enough to keep the X350 in the air. I’m not sure about your OSD and your RTL questions as I’ve never done extensive testing on those 2 features. Maybe you can ask at the RCGroups forums. Here’s the links:

      http://www.rcgroups.com/forums/showthread.php?t=2077292

  3. handydan says:

    I bought my first QR X350 Pro in January but did not fly it until mid April. I have a good sense in solving seemingly “unexplainable problems” like the one I’ve been reading about concerning the QR X350 Pro. I believe I have found the single problem that creates these unusual flight characteristics of this machine. The bottom bearing on the motors appears to be spinning in its socket, sometimes known as a spun bearing, this leads to overheating, reduced power and ultimately high harmonic distortion. I believe the harmonic distortion is the cause of the failure of the electronic instruments not operating properly, including the LVC being activated at the wrong time. Between what I have experienced and what I have read there are many software and instrument failures at the center of the final crashes of this Copter. I fixed my problem by drilled 5 holes under each motor, one in the middle to access the bottom bearing and one hole between each motor mount bolt to give the motors airflow. Additionally to temporarily keep the motors running cooler I sprayed the bearings with lubricant and balanced the motors and props however this will only work short term. I have ordered 4 new motors from an alternative supplier that advertises having bigger and higher quality bearings than the original Walkera ones, this is the only permanent solution since it is the design of the motor that is at fault not just poor workmanship and quality control.
    I hope this helps some of you.

    Dan

    • admin says:

      That’s a very interesting observation there, Dan. I do agree that the motors on the X350 Pro vibrate a lot and run very hot. One guy even wrote that the plastic below one of his motors had actually melt due to the heat.

      Just last week, I had rebuilt my X350 Pro and upgraded it with a APM Mini 3.1, still using the stock ESCs and motors. When I place my X350 on a table and run the unbalanced motors with propellers removed, I can feel the tremendous vibration they generate, especially at 20% throttle or higher. One can only imagine how much stronger the vibration can get when the props are mounted. Balancing the motors could help reduce the vibrations.

      I won’t be surprised if this extreme vibration is to be blamed for the many problems bugging the X350 Pro, as you pointed out. Something’s definitely going to fail in those solder joints, connectors and ICs after long-term exposure to such strong vibrations.

      I’d would be good if you can share photos of the mods you did on your stock motors and publish them on some blog or in Facebook. Btw, what is the spec and brand of the motors that you ordered?

      The stock X350 Pro motors and body have an odd bolt hole spacing of 16 X 17mm. Most motors out there with similar size have a spacing of 16 X 19mm. I have yet to find a brand that offers the odd 16 X 17mm spacing. I believe the odd spacing is Walkera’s attempt at preventing owners from mounting non-Walkera motors on their X350s.

      To mount aftermarket motors on your X350 Pro you will need to drill and modify your motor arms to accommodate the common 16 X 19mm spacing. But I feel this approach is simply messy.

      Alternatively, you can 3D print your own adapter to fit a 16X19mm motor on your X350 Pro body — this approach is a lot more neat. There’s a guy who sells these adapters, you can find more details here:

      http://www.rcgroups.com/forums/showthread.php?t=2273261

    • x350_noob says:

      Hi Handy Dan, What motors are you putting in?

  4. Lithuanian says:

    Cool article! Thanks! I have Walkera 350 Pro, I flew five times, updated the software and flew two times and when returning home Walkera felt from 30 meters like a piece of sh…sorry, rock. Battery was about 80 %, everything was fine, weather was clear, distance from transmitter ~50 meters. I did not know what to think. This crash cost me 200 Euros. Sadly, my shop could not tell the problem. Thanks to your article, I now the problem and will try to fix it. Thanks, man!

  5. x350_noob says:

    I have had the x350 pro for 2 weeks now. My first flight was indoors and was perfectly balanced. My second fly was outside and was perfect, hold worked well – even given the wind; it didn’t move an inch, RTL worked as expected landing within a metre of the point the unit was set to active.

    I then watched all the videos on Youtube which recommend you upgrade to 1.7 and change several paramters such as battery voltage to 10.5 and failsafe set to RTL instead of land.

    First flight was strange, the unit just leaned forward and took off soon crashing to the ground, second flight took off to the left doing the same .. 3rd flight I was able to get stable flight by as soon as I hit hold switch – the unit wanted to take off at high speed to the right.

    I have had luck with RTL only one other time now – most of the time the unit slows, hunts .. and then just whips into a full forward race in any direction – very bizzarre behavior.

    15 crashes and 12 props later – I have now managed to downgrade the firmware back to 1.5 and set all parameters back to default using your link however RTL and Hold do not work as they were in my very second flight.

    It’s frustrating to say the least Walkera charge good money for this product but it seems that if you try to connect to and change any of the settings the unit becomes very unstable. I really didnt want to by a Phantom, but all my mates who fly have rarely – if ever had a crash.

    At least I can drive stick real well now 😛

  6. mervyn says:

    Hi,
    For most of the RTF X350 set it comes with Devo 7 TX. Recently i just purchase X350 Pro Ver. And it comes with a Devo10 but the RX is RX705 which means it a 7 channel RX. Which it suppose to come with a 10 channel RX.
    But my main concern is, with the stock 7 channel RX.
    Can i perform,
    IOC, Auto take off, GPS Hold, Auto round circular, Gimbal full brushless control.
    Is it enough for 7 channel?

    • admin says:

      Hi Mervyn,

      You can still fly the X350 with camera and gimbal with just 7 channels. However, you might have to sacrifice a few functions and assign only the most important functions to your TX such as RTL. Gimbal control alone takes at least 2 channels. For a X350 with camera and gimbal I’d recommend at least 10 channels.

  7. Johan says:

    Hmm have the problem with my Walkera 350Pro and 2D gimbal using the Devo7 transmitter. I had AUX 2 knob working for the gimbal but then I was stuck in IOC. No IOC can be turned of as per factory settnings but I have no control over the 2D gimbal. Not only doesnt the AUX2 knob works, but the Gimbal it self is not stabling. I dont need the AUX2 knob to adjust the vertical. But i do need the Gimbal to level. What I am doing wrong?

  8. jake says:

    Bro, I have a problem. Looking for solution that u may provide. I am realy upset with my devof12e transmitter. It got stuck if I click the EXT button, and it even dosen’t turn off even I power off. I have to remove batteries to power off and If i on normally without holding EXT button. it shows a message in monitor that “devention-saving-please waiting”. Please help. I found no solution anywhere in the net,

  9. Angelene says:

    I have a problem please help my Walkera x350 does not want to lift at all please help

  10. Ivan says:

    Hi

    I came to this website looking for a QR350 pro vs DJI Phanthom 2 comparison, and to be honest now im feeling kind of regret of choosing Walkera.

    I bought it on April and i started flying until July, so far i’ve had only one crash while i was proving the Return to home Function, that test made me require a new ESC.

    Now is functional again but i haven´t practiced a lot because Im concern about the issues i keep having to manually keep stable the Quad:
    The takeoff always is complicated because the quad tend to go to one side or the other before start to actually flying, that causes propelers to crash with the ground. I have calibrated Quad and Devo F7 Controller, but the results are the same, I basically want to know if that’s normal? Do i need just more practice? or is something uncommon that might be caused by some issue with the QR350 pro?

    I must say that i have the firm intention of making a business out of this recent purchase, so any comment is welcome (BTW once its on the air keeps being a problem)

    Thanks for your comments

    • admin says:

      If you plan to buy a drone for a small business, I recommend the Yuneec Q500 4K. This is one of the best value consumer drones around for under $2000, if not the best. If you find the Yuneec’s price too steep, then I recommend you get the Phantom 3 Standard ($999).

      The X350 Pro is notorious for poor quality control. You might want to balance the motors and propellers. The motors are very badly balanced and produce A LOT of vibration which can cause a lot of problems. The newer X350 Premium has much better quality control over its predecessor but is similarly priced as the Phantom 3, so you might as well get a Phantom 3.

      As for your takeoff problems, I think it might be due to lack of experience piloting quadcopters. I suggest you buy a cheaper drone like the Syma X5C-1 to sharpen your skills.

  11. Allen says:

    Hello,

    I’m Allen from Bonka Power. we sell Bonka LiPo Battery suit for FPV Quadcopter, RC Helicopter,DJI Phantom etc.

    Such as:1800/2200/3300/4500/5200mah 3S for FPV Quadcopter,RC Helicopter,DJI Phantom.

    Our battery with high quality and best price, welcome you contact me and buy our battery to test,that’s no problem.

    Hope we have an chance to do business and establish good friend relationship in the nearest day.

    Waiting for your reply.

    Best Wishes

    Allen
    skype:bonka-allen
    email:sales5@bonkapwer.com
    http://www.bonkapower.com

  12. Nikos says:

    Hello ,

    I need help. I own a qr350 pro and i had some good flights.
    By mistake i change some settings in my devo f7 and its not working correct. How can i restore the devo F7 settings to my QR PRO default settings.
    I also reset the model in my devo device.
    Thanks in advance

  13. yuval says:

    HI
    How do I connect the bt-2401b to wallkera qr 350 pro?
    i connect it to Smartphone But fails to connect with the wallkera qr 350 pro.
    Thanks yuva

  14. Alice Tayllor says:

    Now this is actually an honest review, and I really appreciate that! I loved that you included the “suicide” feature 🙂 Thanks. I did some research on this model, and beside your review the only one worth mentioning was this one http://mydronelab.com/reviews/the-walkera-qr-x350.htmlin which they mentioned that the drone doesn’t come with any valid warranty from its suppliers.

  1. February 23, 2016

    […] terdapat sedikit bug mengenai drone ini, seperti dilaporkan Thedronefiles, Walkera QR X350 PRO ini mengalami crash saat terbang karena fitur LVC (Low Voltage Cut) yang […]

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