TZ-90 V2 Build
I have my TZ-90 V2 about 50% complete. Overall the kit is not bad. Here are the big issues thus far:
My initial impression opening the kit was just like the TZ-50 V2. It is very well organized and logically packaged with each of the pre-built sub-assemblies safely tucked away. No items were missing from the kit. The other item noticeable is the excellent machining and overall care with the design of the machine.
One item, the canopy did get damaged in transit. I believe this was due more in part to the additional packaging material that Hobby King placed in the box rather than the original packaging JS included within the kit. The damage was centralized in the black painted portion of the canopy and can be fixed with a little effort.
The first step I did was to verify that the frame was square and that the each bolt was tight. No issues found and each bolt was indeed tight.
The next step was to pull the fuel tank and replace the fuel tubing with the black fuel tube that is far better for 30% Nitro fuels I use. The assembly of the tank was performed perfectly by the assembler in your factory, but I know from experience that the tubing supplied in your kit is good for only one or two weeks once exposed to 30% Nitro fuel.
Ok, down to business. Below are the items that were of issue:
1) On the main frame assembly, I had to slot the four (4) motor mount holes approximately 1.5mm forward to align the motor with the clutch and prevent binding of the clutch. This seems to be a common problem with the kits. Internet blogs have others have that had the same issue. This issue would be better addressed by moving the engine mount holes rearward 3mm rearward and then slot the frames 1.5mm rearward from the present position. My concern is that I have slotted the frame too far forward and may have compromised the frame strength.
2) I replaced the clutch lining with a T-Rex 700 clutch. The liners cost me $5 (USD) for two liners. No big deal, but the original rubber liner in the clutch is too soft and wears easy. It also allows the clutch shoe to spring too far outward during flight leading to plastic deformation of the clutch shoe and permanent damage to the shoe. Again, this is an issue on the internet blogs regarding this kit.
3) The drive gear for the tail uses two M3 X 8 Socket Headed Cap Screws. This is not good and I replaced them with a M3 x 30 shouldered bolt. The threads in the main shaft required boring and honing. The reason for the change is that the cap screws will fail. Placing load on the threaded portion of the bolt is bad as the threads are stress risers that do not handle the shear from the drive nor the fatigue. This is an issue that Thunder Tiger Raptors had early on, an issue that led to the crash of my Hirobo Freya 90, and one that I will not allow to occur on this model.
4) The fan hub is not threaded for YS engines and is not noted in the user manual. I re-tapped my fan hub and ordered the YS version from AMainHobbies for a later install.
5) On Page 10, section 8.0 of the assembly manual you should indicate that the tail belt should be installed into the frame at this point. This will prevent disassembling the drive train later in the process. Experienced builders will recognize this, but new builders will not.
6) The main shaft had significant burring of the ends from machining. This was easily removed with 220 grit sandpaper, but worth noting. I have had many other kits from virtually every supplier with this same issue.
7) On the main gear assembly, the brass ring was either installed crooked or not machined flat. In either case, the upper snap ring was binding on the brass portion of the one way clutch and I had to machine off 0.003inch to provide clearance and eliminate binding. I also had to lightly oil the one way bearing because it was dry.
8) The clutch shoe one way bearing was dry and required oiling.
9) Both tail thrust bearings (item 580-002) were not greased during assembly and one bearing stack-up required shimming to eliminate play.
10) Both head thrust bearings (item 580-005) were not greased during assembly.
11) Assembly manual did not indicate the placement of the washer/shim that should go below the main shaft lock ring (item 122-018).
12) Tail belt skips/jumps easily during static load testing on bench. Not terrible as it take a fair amount of torque to make it jump.
If I find anything else I will be sure to post. I expect to be up and flying by this or next weekend...weather permitting.
Hope this helps.
, 3/4 of a pound is alot of extra weight
I can see this will be my new how low can you go inverted heli
