120 sr tbe

[oldcelt]

I've only flown this model twice. First time a stable hover was achievable. Second time, a week later, tried to let it stabilise at about 4ft off the ground but it now has developed the dreaded TBE. I can't see or feel any binding anywhere and the flybar looks as new. All the links are in good condition.

Any suggestions please?

[kieranar]

120 sr tbe

This may help http://www.rchelicopterfun.com/toilet-bowl-effect.html

[450man]

The 120SR does wander about a bit in the hover all the time. It can be pretty stationary for a few seconds but then it tends to slowly move around. Mine does that.

The issue with the 120SR is the 45 degree flybar. It causes the heli to "bounce" when a sharp control input is made and when you are learning you tend to make larger movements than totally necessary... it is just part of learning.

I am not suggesting that there is nothing wrong with your particular heli as I haven't seen how your heli is behaving but it is worth bearing in mind that apart from TBE the 120SR does have this "bounce" behavior. You do get used to it.

[oldcelt]

This may help Dealing With Toilet Bowl Effect On Your Micro Coaxial RC Helicopter

Thank you for trying to help. However, that page deals with coaxial helis. The 120 SR is a whole different kettle of fish having a single rotor and a 45^o flybar.

[oldcelt]

The 120SR does wander about a bit in the hover all the time. It can be pretty stationary for a few seconds but then it tends to slowly move around. Mine does that.

The issue with the 120SR is the 45 degree flybar. It causes the heli to "bounce" when a sharp control input is made and when you are learning you tend to make larger movements than totally necessary... it is just part of learning.

I am not suggesting that there is nothing wrong with your particular heli as I haven't seen how your heli is behaving but it is worth bearing in mind that apart from TBE the 120SR does have this "bounce" behavior. You do get used to it.

This effect takes place without any input except enough throttle to raise it about 4ft off the ground - right hand held clear of the elevator/aileron stick.
It starts gently and gradually increases the size of the circle until it has to be landed before it crashes.

[450man]

mmm. Check your links are all fitting snugly and not bent, replace if in doubt. Check your flybar is unbent... even a very small bend can make it do funny things. Replace it if you have any doubt. On one occasion I couldn't see any bend in my flybar but I replaced it anyway out of desparation and it improved things hugely!

It does sound like a flybar issue of some kind.

[oldcelt]

Thanks a lot. I have, in fact, already ordered a couple of replacement flybars so we'll see if that solves the problem. Have you tried any of the advertised upgrades for the flybar, like Xtreme for example?

[450man]

No. I decided early on that I wouldn't do upgrades until I could appreciate them and when I was flying the 120SR I was crashing a lot! The stock parts are cheap as chips and so I just treated it as a learning tool to get me on to CP helis. The next heli I got was a MCPX V2 and now I can fly it I have upgraded the swash and head on that to CNC but I didn't do that whilst I was bashing it into things all the time.

It is a personal choice. I chose not to upgrade in the expectation that I would learn not to crash as often. Some people say upgrade while you are crashing a lot to save on breakages and repairs. The upgrades still break but may be not as often and they are expensive. I preferred to use stock and not have to worry about price.

[oldcelt]

Yeah, I like your reasoning. I was tempted by the enthusiastic reports of the upgrades, especially the flybar, but common sense prevailed and, like you, I'll keep trying to get it sorted with standard spares for now.

I have an mCPX V2 which I've crashed more times than I care to remember (currently suffering a broken skid). It was a step too far at my level of skill and trying to fly indoors was far too much of a challenge - the village hall is not big enough. I'm waiting for some reasonable spring weather to get it out in one of my fields to get some practice in. Fingers crossed that a bit more space will give me chance to correct my ham-fistedness before hitting something. I have to say, though, it's a tough little beast except for the skid!

[450man]

I went through a period where I really thought I'd never get it. I was very close to giving up then, quite suddenly it seems, it all clicked into place. Not that I could suddenly fly around, but suddenly I started to improve enough for me to see that it wasn't a lost cause. Stick with it

[oldcelt]

Oh, I'm enjoying it far too much to think of stopping, much to my wife's disgust

I'm enjoying building the HK450 CCPM almost as much as flying the models. It's been my winter project and is getting close to completion. That is definitely going to be an outdoor, 10 acre field, maiden flight.