450 inverted problem

[treff]

My 450 will sit in a hover very nicely. It's very stable almost to being boring. But! When it goes inverted it as a mind of its own taking off, usually backwards
for no reason. I can not work it out. C of G is good. I got 12 up and 12 down so I can not thing what the problem is. It will not hover inverted.
Any thoughts are most welcome. Thanks guys

[Marius]

Any loose objects on your heli? Battery, canopy, rx?

You've checked that your swash is level at 0° of course, but have you checked that it is also level at -12°/+12°+?

[treff]

Hi Marius, thanks for the reply. Yes everything seems nice and level, nothing loose. It is quite strange.
I may try a change of blades to see what happens. I can not think of anything else to be honest. It just
will not hover inverted. Its like it somehow falls off balance and I just can not react quick enough to keep the
hover going. I will let you know if the weather holds tomorrow. Thanks

[Superbad]

How are you checking the CG of your Heli

[cml001]

What Marius said.

[DOG]

I agree with superbad...... How do you check your CG? I grab the heli by the main rotor head and hold the heli straight out from your chest. Then see If tail is heavy or the front is heavy. Check with battery on. That's just my way of checking.

[Superbad]

Here is the thread I started on testing CG of your heli It has Lees old Video of how to do it
http://www.rc-hangout.com/forum/viewtop ... =143&t=418

[DOG]

That's the video I was talking about superbad. I didn't know that was lee's video.

[Lee]

If everything is set up correctly, I would say it has more to do with the centre of mass.
In a normal hover, the weight is below the rotor, so is inherently stable.
Inverted is like balancing a stick on your nose
Easier way to see it visually.
Hold the heli by the head. It just hangs there.
Now hold the heli by the head upside down. It wants to fall back over.

The gyro will do its best to keep it inverted, but it take a lot more pilot input to keep it inverted.

[treff]

Thanks all for the replies. Yes CG is okay. I've changed the mains to different ones and still the same. I think there maybe a problem with
the 3gx but not to sure. Will try upping the cyclic throws to see if more input will do the trick. Thanks again.

[treff]

Well I found the problem, just did not have enough stick movement. Tried again this afternoon. First tried flips but did not have enough stick. Got it
over 4 times then dumb thumbed and off it went and bit the dirt. Oh well. Strangely blades perfect, everything else quite bent lol. Back to the bench
for this one.

[Graham Lawrie]

It is a lot harder to control inverted hovers, really hard:)

[Marius]

Practice makes perfect!

[treff]

Yes indeed. practice, practice and then more practice. I had the heli set up for stooging around outside the house. My fault I should
have remembered that and changed the setup to be more aggressive. Still lesson learned lol

[DOG]

I was using 360mm RJX blades for my X3. The 362mm came out and now I use them instead. When it comes to inverting hovering the extra 2mm makes a differences. Makes my X3...floaty. I would like to try KBDD 350mm blades. They're smaller blades but wider.

[murankar]

I would have to run that through the disk loading calc I have. Would like to see what the disk loading is. Oh and I have disk solidity also, which is where it figures based on cord width.