Synergy Follow Up
Simon Lockington

The hole burnt into the fuel tank when the muffler wasn't spaced out far enough...

As expected, the Synergy Build article generated a hell of a lot of interest, well this is the follow up to it.

When the last article was written, I hadn’t yet completed the electronics install as I was waiting for a couple of bits to turn up.

As I was finishing the install I realized the kit isn’t supplied with antenna tubing, then I also realized that the skid braces don’t have holes in them to hold the antenna tubing. Luckily I had some JR antenna tubing lying around so used some of that, threading it along the side of the frames and up the boom supports.

While not a deal breaker, this omission is a pain in the ass.

Another thing I’ve only really just realized is due to the size of the balls on ball links. The things are much larger than normal ball links and so my ball link pliers don’t work very well at all! I need to get some much larger ones as at the moment, trying to take the ball links off is very difficult with these pliers.

Fitting the GV1 sensor is a piece of cake and it lines up perfectly with the magnets in the clutch bell.

I set the machine up with 11 degrees of collective pitch both ways and 8 degrees of cyclic pitch.

With the machine now setup, it was out to the field for the first flights.

Got the YS started and took the heli out minus it’s canopy to the flightline and set it down. Spooled the machine up and found it was too rich so leaned it out some. As I was backing away from the heli my neck strap caught on the flight mode switch and it went from idle to 100% throttle in about a half a second…

The resulting high speed pirouette snagged the tail on the ground and stripped the bevel gear before I could work out WTF had happened. I’d injured the machine before it’s skids had even left the ground!

However, examination of the bevel gear revealed that the teeth hadn’t sheared off fully, so I felt it would be fine for some hovering.

FLYING
I spooled the machine up and lifted it into the air. The heli sat nice and smooth with no fuel foaming and the vertical fin was very smooth.

Compared to the agricultural gear noises of the Vigor, the Synergy was noticeably more quiet.

When left alone, I was quite surprised at how well the Synergy dealt with the wind gusts, however if you gave it a little cyclic, the machine would react suddenly and with determination.

I hovered it around for a few minutes then began doing a couple climb outs to try some autos. The engine pulled strongly and the heli felt very light in the air.

Autorotations were a breeze as expected, the Radix blades auto great.

However after the fifth auto, the engine started to run a little erratically and then went very lean so I set it down to see what was going on.

The issue became clear very quickly, the tank had expanded more than I anticipated and pressed against the hot muffler which burned a hole through it. This bought the days proceedings to an end.

The explanation here was the Hatori muffler I ordered has a shorter header than the US marketed equivalent, so anyone using the Hatori 937 should space their exhaust out from the engine a little more.

While I was disappointed to have not been able to get more out of the day, I was impressed by what I’d experienced so far, the helicopter seemed very crisp and responsive.

The following weekend, armed with replacement fuel tanks and bevel gears, the Synergy took to the air again, although the engine was being a little inconsistent which is not usual for a YS.

CYCLIC CONTROLS
The cyclics on the Synergy are powerful. Real powerful. Where Raptors tend to have a ‘neutral’ area around center (a type of mechanical expo), the Synergy most certainly doesn’t. If you breathe on the stick, the heli will move, which sounds awesome, but in reality, it makes it hard work to fly smoothly.

To combat this I’m using -25% expo to help soften things around center, this helped a lot and minute stick movements didn’t stand out so much.

BASIC AEROBATICS
For me to really like a machine, it has to track well through the sky and feel ‘solid’, Robbe Millenniums, Vigors, some Raptors etc are good at this. Ofcourse just about any helicopter can be made to feel like this with some setup adjustments.

Out of the box on the standard settings, the Synergy didn’t feel ‘solid’ in fast, large aerobatics such as F3C style flying. The heli needs to be ‘managed’ through loops as it wanted to screw off to the right a little. At high speed the machine feels ‘light headed’, by this I mean it feels like it will pitch at any moment, not locked in like it’s on cruise control.

Rolls are a bit interesting, the machine rolls so damn quick it’s all over before you’ve realized it’s begun! Rolls are very axial and don’t require much pitch involvement.

Rolls seem very efficient, by that I mean you don’t hear the helicopter load up at all, it just rolls. Quickly.

The Synergy will punish you if you are lazy on the sticks. It will react to each and every input you give it whether you intended it or not, so if you want to do fast and smooth flying, you need to be on your game!

In an effort to reduce the potential for pitching and give the heli a more locked in feel I reduced the flybar ratio to the inner most hole (as opposed to the standard middle hole). This did help the heli settle in fast forward flight a bit better so for me it was a worth while change.

While all this was going on the engine was continuing to run a little inconsistently and I was chasing needles all over the damn place which is really not normal for a YS.

I decided to take the engine out and have a look.

REMOVING THE ENGINE
I had gone through the motions of removing and installing the engine a few times during the build process for various reasons and found it to be pretty straight forward and not a problem.

However after the heli had a couple of flights on it, things seemed to have changed.

Removing the hex adapter had become a problem, it just wouldn’t come off the start shaft. After a few hours of working at it with vice grips, screw drivers and finally resorting to a pound hammer, I managed to get it off.

What the HELL had changed??? Why go from being easy to remove to being a right royal pain in the ass?

Well it turns out that the hex wand on my starter had created burr on the top of the start shaft which had ‘mushroomed’ the shaft which ofcourse, made it near impossible to remove!

Ofcourse with this defect on the shaft the bearing block below the hex starter was never going to come off either so I set to work with the file and sandpaper to try and smooth the shaft up to allow the bearing block to come off.

OK, now we have the shaft smooth, lets pull the bearing block up over it. What’s this? It’s jammed too? What the hell!

It turns out that the pinion had decided to ‘sweat’ itself into the bearings of the bearing block and would not come free. Remembering that there is no Loctite used in this step, it had done this all by itself.

So now, the pinion is jammed in the bearing block which means when you lift the bearing block, the clutch bell fouls on the frames.The problem is the bearing block has to be removed in order to allow the fixed starter shaft to move that would allow the whole engine to be removed. So in summary, we’re stuck.

By now, the frustration meter was moving past high and getting towards extreme.

I discussed my predicament with Bob Johnston who said the best way to combat this was to get a ball ended hex driver, poke it through the holes in the clutch and undo the clutch bolts which would free the engine from the clutch. Once again, Bob’s tip paid off and we were on our way again.

With the engine now gone, I was able to push the bearing block down and free the block with the attached clutch bell. Some heat and gentle tapping then separated the bell from the bearings. Determined for this to not happen again, I got stuck into the top of the pinion with some fine sand paper to clean up the surface.

Hopefully this action of filing down the top of the start shaft and cleaning up the pinion will have prevented this from happening again.

It did help, but it only reduced the issues rather than eliminated them, whenever I have the engine out now, I make a point of running the file and/or sandpaper over the start shaft and pinion as preventative maintenance.

Due to the engine issues I’ve had with this particular engine, I’ve experienced the engine removal process a lot with this helicopter. It’s never been a pleasant experience and I dread having to do it. However, I will say, that before I flew the helicopter, removing the engine was a breeze…

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