Can you tell me what is wrong with my helicopter? (video included)

[andybl]

Hello everyone,
Lateley I have experiencing extremely low flight times with my century hummingbird v4. When checking for a bent main shaft, I noticed that the shaft makes a girtty noise when spinning. I find it hard to tell if the shaft is bent or not, but does anyone have any idea of what this could be?

[ame="http://www.youtube.com/watch?v=-vdiDPlCZoM"]Click here to see the vid[/ame]

Any help would be aprpeciated,
Andy

[Tim Procter]

At a first glance it sounds like knackered bearings in the motor or the main mast.

[liambaker996]

there is a esy way to tell if the main shaft is bent all you do is remove it from the helicopter and role it along a flat surface
but like tim says i would say it is motor bearings
liam

[machasm]

Checked your one-way bearing.
Definately a worn bearing somewhere.

[andybl]

Thanks for the responses, I'll check now.

Would this explain poor flight times?

[liambaker996]

yes this could cut flight times i think other chaps will comfirm this ?
liam

[andybl]

sorry about this (I'm a beginner!).

How am I to check for bad bearings?

I have the helicopter in pieces right now, how do I tell which are bad?

[sacko]

Spin them with your finger inside one, it should feel nice and smooth.

How much is your lfight time being reduced by?

[Tom Burgess]

sorry about this (I'm a beginner!).

How am I to check for bad bearings?

I have the helicopter in pieces right now, how do I tell which are bad?

spin the inner race, your looking for notchiness/slop

[andybl]

Well I can only seem to find one bearing, if I am looking at the right part:
Heli-World - Detail

I have also checked the main shaft collar and that seems to move freely?

[robgt]

Are you sure that noise is coming from the mainshaft area and not the motor itself?
Cheers,
Rob

[andybl]

the motor spins fine by itself.

This seems to have gone from bad to worse, now its making a worse sound, I'll upload a video now..

[leckylee]

just a thought
if it is a brushed motor are the brushes sparking, that would cause a noise. way to check: spin the motor on it's own
hope this helps
lee

[andybl]

I have reassembled everything now, and now this noise?
[ame=http://www.youtube.com/watch?v=D--5yqxQgBw]YouTube - bad to worse![/ame]

Anyone have any ideas? I'm at a really loose end.

By the way, my flight times were of around 30 seconds with a full battery. I'm sure it's not the motor because it doesn't get hot fast.

cheers
andy

[Smoothound]

Unmesh the motor and twiddle the shaft between your fingers so its spinning in the shaft bearings any roughness they are shot.