Century UK MX2 Issues. This article is more of a heads up for those of you with this model or thinking of purchasing one. You don't expect too much for the price but hope it wil give you some decent length of service. When it is flying it is great fun and fairly lively which you should expect from an aerobatic model. Being mainly a scale flyer, I purchased the MX2 to practice aerobatics, get used to large control surfaces before committing my more expensive models to the airspace. My thoughts were if I break it I can probably patch it up and not have lost a lot of money, especially if I can retreive the LiPo and receiver. With this in mind here are few anomalaies to be aware of.
Update 1: I have had number a number of successful flights with this large foamie MX2 aerobat. It takes some time to get the CG right by moving the battery back and forth along the fuselage tunnel. I am using GensAce 4000maH 4 cell Lipos. After some experimentation It was discovered very early that to achieve a decent Centre of Gravity it was necessary to move the ESC out of the tunnel up front and secure it to the motor mounting which is probably the best idea anyway because it will receive adequate airflow and less chance of overheating and burning out which will inevitably mean loss of model. The Lipo can now be postioned right up to the front of the tunnel/battery space. Held in it's hidden away position by a piece of stiff foam that holds it fully forward and still allow airflow through the tunnel.
Update 2: Recently, after trying to take off on longish grass and rather spongy field surface, which entails full throttle, full up elevator to get rolling and fortunately not actaully getting into the air the motor made some strange noises similar to the timing being way out or massive bearing failure. After returning to the Pits I discovered that I could pull the prop, spinner and the motor casing forward virtually pulling the motor apart. No more flying for this baby today! But I did have a suspicion as what this may be.
Back home on the workbench I removed the motor from the fuselage, removed the motor bracket and yes, my suspicions were correct. The circlip was missing! I took the motor apart and studied the other components. No issues there, magnets secure bearing appeared to be serviceable. I found another 4mm circlip and after putting the two halves of the motor together I struggled to get the circlip to locate. On further study thats because it was not visible at all. Aha! Friday night job or just quality control as such as it may be. The circlip had never been there in the first place and only my excessive loading of WOT on a static model brought the issue to bear.
A new motor from Century is £39.95 plus P&P. But am I laying out £45 GBP for another batch of trouble? I will see if I can solve the motor myself first. Looking at the photo on Century's website although not scientific, it appears that the shaft should be about 1mm lower in the casing centre boss. Removing the 2mm grub screw from the casing which locks the shaft to the outer casing, it took some fairly firm taps with a hammer and drift to to get the shaft to move but eventually I succeed without damaging the casing. On reassembly of the motor, lo and behold, the circlip groove now is just visible above the rear bearing. New circlip engaged and the motor is fixed. £45 GBP saved and still in my wallet and no thanks to Chang Hi Woo who assembled it.
Before, considering repairing the motor my thoughts turned to replacing the motor with something a little more powerful. I had such a motor waiting for a home. A GT2826-04 (910 watt) 870KV Outrunner. This would usually be located by a generic "X" plate mount. Looking at the original MX motor mount, a piece of folded galvanised steel it appears that it was too small to take the 2826 motor. In fact the motor mounting holes are not evenly spaced either but offset and also to close together compared with most other motors. I think this fact is a crafty, underhand way of locking you into purchasing the correct spare parts. Nice one! With this discovery, my alternative option was binned so repairing or replacing the motor was my only quick option if I was going to fly this MX2 by the weekend, weather permitting.
Update 3: I had to replace an elevator servo also after few flights. THe 9g servo for the rudder and elevator are not really up to the job. Again, these micro servos appear to be a odd size too. None of the sub-micro servos I had would just drop in. I got round this problem easily. All that was required was some careful cutting of the elevator servo cut-out and I dropped in a Hitec Mini metal gear. Job done!
The prop driver seems to be an odd size too although the shaft for the prop is 5mm. Again like the P51, the prop driver has custom face so that the bespoke spinner backplate slides and locates on. The prop nut purely holds the prop back tight against the prop driver. The three blade prop looks the part but is plastic and the first "nose-over" will break one blade off. This may also take a chunk out the spinner backplate making it unbalanced. This WILL require you to purchase from Century a spinner assembly and another prop although they are cheap to buy. But how often and will they stay in stock?
My workaround was to replace the spinner with an Irvine 2 1/2 inch spinner in black and replaced the 12 inch three blade with an APC-e 13x6. More resilient to "nose-overs" and no noticeable difference in performance. I sprayed my prop with Acrylic car paint in satin black. Do it lightly and check prop balance afterwards.
So, if you have one of these models or are weighing up whether to buy one or not and you decide to go ahead just verify or check these items first that I have highlighted preferably before flight. The bottom line is, yes it's a nice flier for the price and you will probably have hours of fun but some quality issues need sorting by yourself though.
Fly and Enjoy!