After 240 or so flights, I was wanting to 'tear down' my Vigor CS and inspect everything and rebuild it. This job was pushed up the priority list when the heli started playing up like it never has before at my last competition. As soon as it lifted off the pad in the first round it blew a brand new silicon coupler on it's KSJ two piece exhaust and proceeded to smoke like it was on fire. Luckily I had a Muscle Pipe II in the car and I quickly bolted that on for the next round. After a little retuning I got through the second round, however just as I was about to go into the third I was in the start box and noticed one of the push/pull arms flapping around reflecting in the carbon frames. Luckily with the help of others I was able to get the heli fixed within the allocated time and I completed and won the third round. The heli was clearly upset about something as it never ever plays up like this so the rebuild project became an urgent priority.
The night after returning from the competition I began stripping the heli down so I could inspect each part and if necessary, replace. I started investigating methods on cleaning the exhaust systems and other surfaces that had crusty 'gunk' on them.
Ofcourse being a bit too keen for my own good, I acted upon the advise given
in a few posts to boil the parts in hot water with detergent. Thinking 'Cold
Water Surf', the clothes detergent, would be a good start, I boiled the exhaust
systems in this brew and yielded nothing but a change in colour to dull silver...
For other items such as the carbon frames, I simply wiped them down with a good cloth, for bearing blocks or other metal surfaces that had build-up, I sprayed 'Brakleen' on them which moved the crap very effectively.
To get the MPII nice and shiny again, I brought some 'Blue Magic' metal polish creme and spent a few hours with various polishing rags. The end result is much better than what I started with.
I had installed an OS 91SX-H engine in this helicopter when it was first built and it had given nothing but stellar service during the last 240 or so flights, however I decided that I would put a new C-Spec engine in and put the SX-H in my plank. To that end I dismantled the engine and replaced the bearings and ring, put the two needle carb back on it and installed it in my plank for running in.
The fuel tank was inspected for wear and flushed out as well as the clunk lines being replaced. The soft material that the tank sits on between the frames had rubbed through, so I replaced this with fuel line that I cut open and superglued to the frames.
I replaced the main shaft and pinion bearings, not that there was anything particularly wrong with them, just didn't want to give the heli any excuse to give trouble.
In removing the drive train bearing blocks I noticed that the clutch bell had been 'fretting' in the bottom bearing that goes just below the pinion. My mate Darryll said he could 'bush' the bell back up which would save me having to purchase another. The bell had fretted quite a bit and I was lucky that I didn't get any radio 'hits' as I'm sure I would have in the near future.
While I had the whole heli apart, I decided that now would be an opportune time to install the 8:0 gear ratio. Installing this gear ratio (11 tooth pinion and 88 tooth main gear) requires ovaling the pinion bearing mount holes in the frame and milling 1.5mm off the engine mount. Darryll quickly milled this off in this lathe and I was in business.
Fitting the engine took a nights work in checking and adjusting alignment. I had had issues with the Standard Vigor when we installed the 8:0 ratio with engine alignment and knew to check this well with the CS. This was a long process of doing up and releasing bolts then doing them up again to ensure the engine was aligned properly. To check this I would rotate the fan and look at the starter shaft coupling to ensure it wasn't turning. When it didn't turn while rotating the fan, I knew I was very close.
At the last competition a fellow pilot had commented on how stiff the links on my heli felt. I would have thought that they would have worn in by now, but it was apparent that they hadn't. I spent quite a lot of time with a ball link reamer to loosen off the pressure on these links until they would 'hang loose' under their own weight and not stay 'outstretched' as it were when they were detached.
For piece of mind, I replaced the switch harness and sent away all the electronics
(gyro, receiver, servos etc) for checking. I'm glad I did as they found that
one of the servos had been mounted incorrectly in that it was rubbing on something
and having vibrations transmitted through it. Although the damage was very minor
(replacing a case and gear set etc) this was an issue that I was not aware of
I pulled the tail to inspect the contents of the tail case. I checked the drive shaft bearings by uncoupling the shaft and rotating it to see if I could feel any notchiness or any noise in the bearings. They were fine. Inspection of the tail gear box yielded no problems either. All grub screws were checked for tightness and the tail was re-assembled.
Again I spent a lot of time setting up the mesh between the drive shaft bevel gear and the split gear on the main shaft. Vigors make quite a distinct noise when the mesh is incorrect and you can feel a harshness through the drive train, minute adjustments can make all the difference. The same holds true for the bevel gears in the tail gear box. If they are too tight, the gear box will emit a lot of noise.
I pulled the main shaft to check for straightness and checked the rest of the head. I had replaced the dampening system a couple of weeks earlier so left that alone. The one way bearings in the hub were re-greased and the head re-installed.
The electronics were next to be installed which took a nights work and I was very careful to ensure that the servos weren't rubbing on anything. I took a good amount of time to reset the throttle linkage properly.
Once installed, I went through my setup again checking pitch curves and linkages for binding. Happy with it all, I put the heli away on charge and went to bed. Next morning with fresh concentration and vision again, I went over the whole heli again checking for loose bolts and fittings, seeing none it was time to head to the field for some test flights.
After another pre-flight check to see if I'd missed anything in the previous seven or eight checks and then it was time to fire the beast up. I intentionally left the canopy off cause you just never know and I really didn't want anything to happen to the canopy.
The C-Spec fired up immediately and lifted off into a nice rich hover with a 'diesel-torque' like tone being emitted from the MPII. No visible shakes from the heli and only a few clicks of trim needed. On completion of this tank I again went over the heli to ensure nothing had come loose. After the fourth such tank of running in, the engine was really starting to settle down and get even smoother.
I have intentionally left the GV-1 switched off until I get the needles fully sorted. On the heli's seventh flight I started a bit of fast forward flight and some mild aerobatics such as loops and rolls. I'm very impressed with the C-Spec, MPII and 8:0 combination. The heli just sings on it. Once I have more time on it, I'll present a more qualified opinion.
Although the refit was a fairly major project involving about two weeks of late nights, I'm very happy with the result, the heli is flying beautifully (like it always has) and it's not telling me that anything is bad (you know when your heli is trying to tell you something). Hopefully I'll get another 240 flights of trouble free flying!