Building the Synergy N9 - Page 2
Simon Lockington

Main shaft fitted in the auto hub and plastic mainshaft bearing blocks.

First frame beginning assembly.

The plastic engine side mounts bolt through the frames into the metal engine block.

The factory provided governor magnet recesses can be clearly seen in this picture.

My particular helicopter needed a little bit of dremelling to the front shroud mount.

The first frame just prior to the second one being fitted.

Second Frame fitted.

Servo tray just prior to servo installation.

Plastic cyclic servo bell cranks

MAIN GEAR/CROWN GEAR ASSEMBLY
It’s about here that we really get introduced to some of the heavy duty engineering that the Synergy has going on.

That great big main gear bolts onto the hub into which goes the sprag bearing assembly that you have to build. At first I thought this could be a intricate and complex process but infact it wasn’t. A lot of care must be taken to making sure you have the sprag bearing inserted in the right direction else you’ll get no drive to the mainshaft!

The sprag bearing comes in the kit with a rubber band holding the teeth in. I have no idea what would happen if you took the band off with no other constraining device, so I opted not to find out! I inserted it in the Sprag Outer Race by slowly removing the band as the bearing was pushed into the race. This ensured the sprag teeth were always ‘compressed’. I then coated the bearing in Tri-flow light oil.

A sleeve is then inserted through the completed bearing assembly (the sprag bearing teeth do not make direct contact with the mainshaft).

The whole assembly is very heavy duty indeed. Compared to the relatively ‘light weight’ Vigor assembly, I really can’t see how any ‘locked hub’ problems would occur.

The CNC machined plastic crown gear is mounted on a fully supported platform (ie the platform supports the gear right up to the edges).

MAIN SHAFT ASSEMBLY
The Synergy uses a 12mm mainshaft which passes through the autorotation hub via two plastic bearing mounts. One area that I was surprised with was the size of the main shaft bearings. The height of these bearings is only 5mm whereas in the machines I’ve been used to, these bearings are normally 7mm high.

However, the effect of having shorter bearings may be somewhat offset by the dampening qualities of plastic bearing mounts. I’ve found that machines with plastic bearing mounts seem to have less bearing damage than a machine with metal mounts.

It should be noted as well that the mounts are metal threaded inserts in the same way as the Raptor which is an excellent system.

There is a shim provided to lift the height of the tail crown gear if a mesh adjustment is needed later on in the piece.

MAIN FRAMES
You build the N9 up one frame at a time by attaching the three metal cross braces and the large vertical front frame plate which has the servo tray mounts attach to it..

The fuel tank grommet material is very interesting. Easily the most heavy duty and durable material I’ve seen on any helicopter and I’d love to get some to use on my other machines. It takes a bit of work to fit, but once fitted works perfectly.

The first half of the engine mount is then attached which the large aluminium center block attaches to the frames via bolts that thread through the plastic side mount through large slots (for vertical adjustment) in the frames.

The main gear assembly is then fitted and the mainshaft collar adjusted to ensure no vertical play. Very straight forward.

Fitting the engine assembly is next. You can add a variety of shims to ensure correct horizontal engine alignment and ofcourse vertical adjustment is easy via the engine mount slots.

The cooling shroud bolts into the slightly slotted frames. However on my machine, once the engine was installed I noticed that the front of the shroud sat noticeably higher than the rear which was causing the shroud to foul on the fan. No amount of mucking around seemed to fix it, so I vertically slotted the horizontal slots a little with the dremel which lowered the front of the shroud and fixed this.

I discussed this issue with some other guys who hadn’t had this problem so perhaps it was just me.

The engine is bolted into the engine mounts by two large 40mm bolts that thread through the mount and into nyloc nuts on the other side.

The pinion bearing block is mounted into the frames by four bolts, two of which thread through the provided governor sensor mount which is a really great idea.

With these components now mounted on the right hand frame, it’s time to now attach the left which is a very straight forward process. The plastic gyro mount platform is attached over top of the two frames behind the mast.

FUEL TANK/LANDING GEAR
The fuel tank is now fitted to the frames and it’s very straight forward, you simply squeeze the tank through the frames and you’re done!

The landing gear is bolted to the frames via four 3x40mm bolts which can take a fair bit of screwing to get through!

CYCLIC SERVO/BELL CRANK INSTALLATION
Next up is the servo tray installation. The Synergy cyclic servos are all lined up in a row in plastic servo mounts mounted on top of the frames.

The servos connect via pushrods to plastic bell cranks held in place by button head bolts that thread into spacers between the frames.

Mounting the servos is very straight forward. The two outer servos are raised in height by using spacers underneath the mounting tabs. There are Xcell style servo supports that bolt down into the servo mounts.

Much has been discussed ever since the Synergy made it’s first public appearances on the geometry of the plastic bell cranks as the first machine used very small servo output arms to control the bell cranks. This ofcourse would make the servos work harder than if a longer servo arm (or increased distance between the bell crank pivot point and the servo link ball) was used.

It seems now that longer servo arms are used as a distance of 14mm from servo horn center to ball link is now recommended, as are heavy duty servo horns.

The control system is very simple and straight forward. Do I think it’s as good as a Vigor’s push/pull system? No I don’t, but I’ve never been a fan of the Miniature Aircraft system which this is obviously based on. However it does seem to work just fine.

The original prototype machines also had a carbon fibre servo tray, however this has been replaced by a moulded plastic one much like a Raptor. There’s plenty of space for mounting electronic components in recognition of the fact that modern helicopters have a wide range of components to carry these days (gyro and governor head units as well as battery regulator items etc).

The throttle linkage is nice and short between the throttle arm and the throttle servo while on the opposite side of the frames, the tail servo is mounted to a pushrod that connects to the rudder bell crank at the rear of the frames, similarly to the new Vibe mechanism.

SWASHPLATE AND WASHOUT
I know I’ve mentioned the size of the swashplate before, but it really is a seriously heavy duty item.

The provided ball links are similar to Min Air ones in that the ball link has a built in hex driver socket and integrated thread which is great.

The swashplate uses a bearing mounted on the front to slot into the anti-rotation bracket in the same way as the Min Air machines.

The washout is very straight forward except for the attachment of the washout links to the plastic washout arms. This was to be my first encounter with the famed Synergy circlips…

SYNERGY CIRCLIPS
In keeping with the robustness of the rest of the helicopter, the circlips used on the Synergy are very serious. Pushing them onto the pins that secure the washout arms requires a good amount of force. I tried using vice grips to force them on to no avail.

Bob Johnston’s Tip
Drill a 2.5-3mm hole in a block of wood about half a centimeter from the edge, place the circlip over the hole in the wood and tap (ie POUND) the pin through the circlip.

You need to have the hole close the edge for later on when assembling the tail pitch slider.

Bob’s tip for attaching circlips worked quite well. I did it a little differently and used a vice with the jaws open about 2.5mm.

By now you should be well aware that these circlips are not easy things to attach, however by the same token, I’m hoping they stay attached with just as much determination!

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