Synergy N9 – Part Two

For those that missed it, I covered the initial stages of assembly in Part One of this review. Next in line are the composite frames, all the holes of which line up perfectly. You build one side first to include the spacers and rear cross brace and then install the main shaft assembly and engine, thus enabling everything to be lined up and meshed correctly. The liner around the fuel tank cut-out (a very good way of stopping tank chafing) needs fitting at this stage, after which the other frame is added along with the tank and skids. Lo and behold, you have the core of your heli built!

The servos are all situated up front in a composite tray, therefore cutting down the routing of servo wires from back to front etc. Some N9 owners place the gyro in the front on the provided gyro mount, however I found mine worked better ‘out back’ and routed the wires forward, secured with some JR cable clips. The servos are easy to fit, and the drawing within the instructions explains everything well. An offset tail bellcrank (included) allows the rudder servo to be fitted at the front, away from oil and possible crash damage. Said bellcrank enables the tail control rod to run parallel with, and underneath, the boom and into the chassis, whereupon it’s ‘cranked’ to meet a control rod that runs down the outside of the frame to the servo. A simple and nicely executed system that works well.

Moving on and it’s time to fabricate the swashplate, washout assembly and head. The swashplate is a substantial unit that utilises socket caps to facilitate the tightening of the balls and also has a bearing fitted to it as a guide in the anti-rotation bracket. The washout assembly gets you thinking a bit, wondering how to fit the circlips to the washout link pins. This is a tricky operation to say the least, but a call to UK distributors Skyline Models yielded an answer: drill a 2.5mm hole in a block of wood close to its edge, place the circlip over this hole and tap the pin through it. Job done!

The pre-assembled head block comes with the seesaw fitted and utilises a substantial 5mm flybar that should take a fair old kicking. Flats have been filed on the flybar to accommodate the control arms and youll note that the set-up is a ‘closed’ type, i.e. it surrounds the rotor head and offers superior precision. Three different flybar ratios are available, from which I chose the middle version.

The blade grips need to be assembled and the races must be greased before fitting. It’s important to install these the right way round, i.e. with the unit of larger internal diameter (the one with more slop when on the spindle) closest to the head. Incidentally, the head is nicely retained with a Jesus pin and two further bolts on each side.

Next comes the torque tube assembly, which I built with some advice from Bob at Skyline who suggested using Loctite on the splines before inserting into the tube. He also advised to make sure that the setscrews are properly ‘set’ by using a high quality tool and tightening them slightly more than you would normally. Touch wood mine have never slipped, nor have any that have been assembled like this, so it seems like sound advice. As I mentioned earlier the tail box is supplied pre-built, although I decided to check it over. Just as well, really, since not one retaining bolt had been installed using Loctite! I also discovered that the thrust races hadnt been greased.

Finally, in terms of basic assembly, the tail boom is secured to the frames with four through bolts, whilst the rotors use 5mm blade bolts. Oh, and while were on the subject of bolts, youll find a set of rather stylish items for retaining the canopy which, as standard, is supplied in white. My nicely painted job, I must confess, is the handiwork of those talented guys at Canopy Creations. Pretty, aint she?

Having made a decision to fit the aforementioned pumped YS91 I also decided to try CSM’s new governor, the Revlock 20, and their top of the range 720 gyro, which has received great press. The Revlock 20 is an impressive piece of kit, with its LED display to keep you informed of the speed setting. It’s proved faultless in use, is easy to set up and kept the YS controlled with a head speed of 1900. I can honestly say Ive never found it to hunt or be sluggish.

In use the 720 gyro is simply stunning and although I also received the USB interface for the CSM software, in order to tweak the gyro, it isn’t really needed as most things can be done by stick programming. Mind you this does mean you can see everything and tweak the pirouette start and stop rates etc. During the N9’s first flight I found that the gyro would hold the tail in continuous rolls without any alteration… just how I like it! I’ve tweaked a few bits, such as the rates, but that really is all. No doubt about it, the 720 is a stunning piece of kit and, best of all, it’s made in the UK!

I decided to fit a FlightPower 4200mAh 7.2V Li-Po pack and a Duralite voltage regulator to provide the 6V required by the majority of the servos. The exception here was my JR 8100g tail servo, which at 4.8V required the installation of a second voltage regulator.

The YS proved easy to set up and when coupled to a Curtis muscle pipe it has huge power on tap. My only area of concern with this engine is that I would prefer to have the exhaust bolts pass though clearance holes in the exhaust rather than be secured into tapped holes, as aluminium isn’t the strongest of materials in this application and on occasion I’ve had the bolts work loose. And with that, I’ll leave it there for now. Be sure to read Part Three for my Synergy N9 conclusions.