Barrymore

I gave up on my 650 mm CH co-axial heli and have just taken delivery
of something more suitable for beginners, so I'm told.
It's a Nine Eagles Draco, very small. I've been trying it out on the floor
in my lounge, setting the trim switches as I deemed necessary.
While hovering, it does not move sideways, and the tail does not turn,
but it just hovers around in circles, nose always pointing in the same direction.
Maybe this is normal when hovering. Can someone please advise.

pizzano

It sounds like the the "rudder" and "aileron" trim tabs need to be adjusted to counter the constant spin....if you have adjusted as mentioned and it continues to lack the proper response, try re-binding the TX to the RX as shown in the attached link:

http://image.helipal.com/helipal-nin...aco-manual.pdf

Make sure the control sticks are aligned as per the manual when powering it up (both heli battery and TX battery must be fully charged otherwise response to control input will not be as consistant).....check the screen on the TX to insure it is showing the position of the sticks (and trim tabs) in the same fashion you have them set on the TX. Once you have it powered up, the TX screen should display any changes you make to the control sticks (tabs)........there have been a few complaints on this system related to the coordination of control input and flight performance when battery power is down to 50%.......some have gone to a higher rated (mah) battery for the heli with decent results.........if the RX board has "sensitiviy" and "rate" pots, you can try to adjust those to fine tune the output (must be done with flight blades removed from the heli and powered up as normal)........these little 3 in 1 gyro combination recievers are very sensitive and seldom respond twice in the same manner after each flight.........and always perform best with fully charged batteries!

Barrymore

You've given me quite a lot to absorb.
I fully charged the heli battery before use.
Your link took me to the manual that I found and d/loaded yesterday, as the manual in the box is all in Chinese.
The four TX batteries I used came straight out the box.
I set the rudder trim and the nose does not rotate.
I set the aileron trim and the heli does not move left or right.
I bought this lot with a spare 110mah battery and am surprised to hear
that a larger battery is available for this heli.
Finally, what is the RX board? I don't fancy the idea of stripping parts off
at this stage.

xmech2k

Do you mean your control inputs have no effect, or are you just referring to the circles it's flying in while you don't make any inputs? That circular motion is known as the 'toilet-bowl effect'. I think it's something inherent in the design of the upper rotor. I don't know exactly how to correct this, but I know it's been discussed in plenty of other places. Maybe a search here of other forums can help you zero in on it.

pizzano

Barrymore......

The RX board is the reciever/gyro/speed controller (and in your case servos attached) circuit board that is easily exposed after lifting the body off the frame.

From the looks of your system, there may not be any method to fine tune the rates since it appears there may be no adjustable pots.....older versions I have worked on had recievers that allowed for the ability to adjust rate changes that would speed-up or slow down either upper or lower rotor blade speed and you could also adjust the blade pitch some through the linkage rod connection at the swashplate (if they were turn-buckle) applied.

Without the ability to manually (physically) make adjustments, one must rely on the electronic settings to do the trick.....which, in many cases with heli's like yours, you'll end up with extreme controller "tab" settings that will require adjustment after nearly every flight....and by the time you get the bird settled down, the battery will require re-charging......making the actual learning experience that more frustrating.

If you're able to get her stable and start getting the hang of the flight aspects.....I'd suggest moving up to an E-Flight or Walkera fixed pitch bird that has a reliable operating history and parts availablilty.....!

Old 'N Slow

Toilet bowl effect. I have a Nine Eagles co-axial, and it had the same problem. I read this article - http://www.rchelicopterfun.com/toilet-bowl-effect.html - loosed up the flybar, and it was cured instantly.

Hope this helps.

Barrymore

Thanks, guys for all the suggestions supplied.
Yes, I believe my heli IS suffering from the "Toilet bowl effect"
The article is quite technical. I will study it at my leisure.

My original post explained that I had problems flying my large heli.
The RC specialist agreed that it was not easy to fly as it was not
memorizing the trim settings. In his shop he showed me what I should
buy as a starter, very easy to fly etc. etc. I bought it and it is now
the subject of this topic.

Barrymore

I used silicone spray on the fly bar linkage rods as described on that
report on toilet bowl effect. It certainly seems to have helped.