Monday, August 27, 2007

Clutch replacements

Replacements has arrived. New oem clutch, liner, and clutch bell bearing (which is same size as those use in raptor's blade grips , d6xD13xW5). New gears for 9252.
I wrapped 2 rounds of electric tape around the clutch and glued liner in with 30mins epoxy.
Changed the gears and made sure the servo was working by cycling it a few times.

Thursday, August 23, 2007

Sticky clutch

Seems like problems comes one after the other, after the fixing back the tt50 engine, i soon faced another, sticky clutch.

Symptoms: For the past gallon, the clutch was engaging very early, even on very low idle. I thought it was cos the engine was still set to be very rich, the vibrations when the engine is 4 stroking sometimes caused the clutch to be engaged once awhile at idle.

I could still fly but the problem got worse ,so much so that i when i crank start the engine , the blades will want to spin. making the engine impossible to start when holding on to the blades.

Went back dropped the engine and examined the clutch. Found that clutch has sprang opened fairly wide and liner was thin. WY suggested to press back the clutch n try again. i did that n the it idles up nicely but the problem came back immediately after i landed.
Removed the liner for replacement
Found that the starter shaft was making click click noises when turned by hand. It turned out that the clutch bell bearing is notchy. Heat up the bell in the oven n slowly tapped it out.

Notchy bearing
Off to get some spares...

Stripped servo gear

The aileron 9252 servo when turned by hand was making click click sound too for quite awhile already, but it still function normally when power is turn on. I suspect it was stripped, probably during one of the auto rotation crashes. So took this chance to remove the aileron servo to change the strip gear. One of the white gear had broken teeth.

So was out of action again for the next few days...

Thursday, August 16, 2007

Taiwan trip - part 2

Ok so after taipei, i stopped over at taichung for a few days. Its a less vibrant city , things move at a slower pace. Align and thunder tiger factories are located in taichung county but a quite a distant away, naturally the RC stuff are cheaper here due the the close proximity. This is where i got most of the goodies.
Visited 3 shops in the list.
The first shop was which is walkable (25mins) from the train station area where most of the hotels are. Although the shop front looks abit old, it has quite a comprehensive stock list, from cars,tank to planes , helis and even boat. They have some nice gliders but boxes are quite big to carry back...

Next stop was ACME-model. Its located at the outskirts in some sort of industrial area, about 15mins ride by cab from train station. Shop doesn't stock much stuff as they do more mail orders. Warning : Quite hard to find cab back from there.
I did most of the shopping at RC extreme sports. Mostly heli and planes stuff, 10mins by cab from train station. Carries the full Align stuff at quite good price. Shop looks family owned, father, mother, 2 kids were all helping out and owner has good contacts with the Align factory. I wanted the trex600 pro kit which they ran out at that moment, he gave a call to the Align factory and asked if i could wait awhile. So 1.5 hrs later, the align guys delivered the kit fresh from the factory. Hohoho. It so happened that the new Align pipe was just out from the factory, so i grabbed what ever i could. Too bad they don't ship overseas...

The pipe looks like the hatori 522 , abit bigger though. Beautiful chrome finishing and comes with nice little accessories.Compared with a 522.
Got a few pairs of CF 600A Align blades as well, which had some good reviews. Quite good finishing, value for money blades.

Edit 23/08 : Warning some issues with this sets of blades throwing leads out here. Hope its just isolated cases, no flying with these sets til it get solved.

Edit 16/09 : The affected blades were the FGXXXXX series. I had a pair which was affected, contacted Walter at Rotor hobby and he was kind enough to help me send back to Align for replacement even though i didnt buy the blades from him. Thumbs up for him again!!. Got my blades back, going to try them soon.
So a few guys asked how i carried back so all those stuff. Well i asked for a big box from the shop packed all the stuff in, and pad with dirty clothes to make sure they didnt move about. Taped up the sides of the box with masking tape and check-in as Fragile item at the airport. The stuff reached back in pristine condition.

More reviews after i tried out out those stuff. For those looking for Align/TT stuff, taichung may be worth a visit, as its only 2.5hrs train ride away from taipei. Can do all 3 shops in a day. Thats it in Taiwan, didn't explore the southern parts, Kaohsiung has a large lists of shops as well, maybe next time...

Tuesday, August 14, 2007

Discus parts

Discus spares finally arrived 6 months after the crash.

They were ordered from , Canadian base hobby shop specialising in Scale Sailplanes and gliders.

5 more months to go to slope season. :-)

Friday, August 10, 2007

TT50 reloaded

Luckily the engine failed while hovering so autorotated down n heli is ok.

Its simple to just get an OS but this TT50 is not that bad, has been quite reliable and managed to start almost every time. On top of that the fuel consumption is great (12mins per tank) .

I read somewhere in the engine manual that tt has warranty, so i contacted Rotor hobby and told Walter abt the engine. He asked me to bring it down for him to take a look. He examined the engine and commented that it did not have any signs of lean or over heating. its maybe due to too high rpm.

He advised not to run high rpm and use higher nitro/lub content fuel. He then offered to replace the damage parts with half an engine for FREE, so practically i got back a new engine except the heat sink and carb. And he will be sending the busted engine back to TT for further analysis.
Kudos to him for the fast response n service.

The engine was only 5 months old, still not very sure what caused it. I m very sure i assembled back the engine correctly and didn't ran it lean, was shocked at the holes in the casing as well. I have asked around , and some fliers said it may be due to cleaning of the piston, cylinder,etc with scotch brite, which may destroyed the smooth running surfaces...

Another lesson.. Will be using back the replacement and has started to break-in the new engine...

TT 50 busted!!

Last sunday, i took out the engine to install rev max. So took the chance to change the bearings since i was at it i thought might as well do some cleaning up. The piston had some carbon residue on top and a ring of slight brownish patch around just below the ring. The cylinder sleeve has some black patches at the exhaust ports.

So i used scotch brite n clean away the residues on both the piston n cylinder. took out the con rod n clean the inside of the piston as well.

Changed both the bearings and assemble back, everything looks ok. turn the crank shaft by hand it was normal and there were no signs of binding.

After which went to fly, first flight - richen the engine abit as bearings are new. Flight was mostly hovering and slow figure 8 using only normal curves to let it run in abit. Felt it was smoother then before i change the bearings. back plate temp was cool . I thought all was good.

2nd flight - started with normal curve , flew around landed n tested back plate, temp ok. then switch to idle 1. headspeed higher. responsive and quite good power, so i thought great the bearing change works. Then i test the rev max on idle 2. i set the limit too low so proceed to land n increase the limit.

I throttle up again on my normal curve, while hovering at eye level,can hear the engine start to get higher pitch like leaning out. then followed by metal sounds then engine cut...

i thought it was the fan came loose. When i came back, realized the con rod broke n was shocked to see the engine case broken with 2 extra holes!!

Dam what went wrong?
-con rod broke, piston sides broke, engine case broken with 2 holes

-cylinder looks ok.the rest of the engine looks ok except for scratches inside the casing.