Esky Big Lama - Inner Shaft Replacement Tips?

[davidm]

Any ideas before I try buying a new battery?

Thanks,

David

[davidm]

The new page doesn't help, so here's my previous post:

Oct 3, 2010 3:54:30 GMT -6 davidm said:

I've had my ESky Big Lama for a couple of months and (with help from the kind people of this forum) made numerous repairs during that time.

I recently had a new problem, for once apparently not related to a crash: while flying, the tail would twitch suddenly, and occasionally there would be a loss of power and the heli would come down. I assumed that one of my motors was one its way out, and ordered replacements. (I thought it was the one for the lower blades, but ordered both just in case.)

I've now replaced both motors, but I now have worse behaviour. I know I haven't caused it, because I saw it before I replaced the motors too (while trying to work out which was at fault) and assumed that the motor was failing more...

The heli will fly for 20ish seconds (still sometimes showing the tail twitch), but it then appears to lose power and starts spinning to the right - as if the lower blades are not spinning fast enough. No amount of stick-left can correct it.

I've also noticed that sometimes when increasing throttle, rather than the blades starting to spin gradually as normal, the lower blades will start with a jerk. When this happens, the top blades will not start without the lower blades either - the top blades refuse to move faster than the lower blades. However, usually this doesn't happen - both sets of blades can be started slowly and independently. The spinning and power loss always happens.

Any suggestions would be much appreciated. Could a failing motor have damaged my receiver? Perhaps I just need a new battery?

Thanks in advance,

David

[19000rpm]

CG is the "Center of Gravity". i.e., the point where the heli balances at the maximum point of lift. In a heli this point is at the main shaft.

You measure this by picking up the heli, by holding each end of the flybar rod, with the flybar perpendicular to the fuselage. As it is suspended; look at the fuselage, from the side, relative to the ground or a level surface. The fuselage will be parallel to the ground when the CG is correct. If the nose or tail are pointing down then the balance needs to be corrected by adding weight to the opposite end, or moving some components, until the fuse is level with the ground. Moving the battery location, slightly fore or aft, is usually the easiest way to get the heli balanced

[Raygun]

I really dont think it is your battery its possible and you may want to start there but more likely it is your 3in1 going bad it may have took a voltage spike in the last crash and now it is rearing its ugly head.. Ray

[davidm]

Oct 5, 2010 6:52:56 GMT -6 Raygun said:

I really dont think it is your battery its possible and you may want to start there but more likely it is your 3in1 going bad it may have took a voltage spike in the last crash and now it is rearing its ugly head.. Ray

Thanks, Ray. I feared I might be being over-optimistic with the battery theory. :-(

[Solitaire]

Before changing out the 3in1, make sure both rotors are attached to their respective shafts snugly and there is no slippage on either. Also check that there isn't any vertical play in the inner shaft.

Double check that you've wired the new motors correctly. The gyro only affects the top rotor and if the motors are attached to the wrong terminals on the 3in 1, this will promote spinning, although this usually happens immediately and not 20 seconds later.

[bebev]

davidm,
Hopefully you have the control problem fixed by now, but I just want to say that I experienced the same behavior that you had with my Big Lama. Loss of power shortly after lift off, spinning, twitching etc.
The battery and motors were new and so I suspected the 3-in-1 to be bad. Got a new 3-in-1 but still had the problem until I replaced the battery with an extreme 11.1v 850 mah and the problem went away.

Bern

[rudy]

Sept 16, 2010 18:01:12 GMT -6 captjay08 said:

I've gotten and installed xtreme productions gears A and B with outer shaft for the big lama. But the problem is it wiggles so bad. I've checked the gears and they are lock tight to the pinions. I've tried to loosen it a little and same thing happens. Can you guys help me with this? I waited a week and a half for this parts and got me grounded that long and it's kinda frustrating to see it fly like this.

here is the video:

I have also recently upgraded my Big lama with Extreme CNC and extreme hardened blades and I am experiencing the exact same problem. I am new to all of this so any views or advise will be greatly appreciated.

[Solitaire]

Welcome to the forums, rudy.

There's many things that can cause a wobble. First thing, make sure your blades are balanced. Also make sure they aren't too tight in the blade grips. Just snug enough that they don't drop when you hold the heli on it's side. Try that first and let us know.

[rudy]

Thanks Solitaire,

I found the problem. Excuse my terminology as I am still very new to this.

The problem was that after my CNC upgrade I tightened the lower blade holders to the outer shaft. What I did not do was to tighten them into the holes of the outer shaft.

The way that I picked this up was by holding the outer shaft's gear tight and then turning the lower blades with my other hand. There was a little bit of play.

After tightening them correctly into the holes of the outer shaft all is working right.

[Solitaire]

Good to hear you got it sorted, rudy.