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Dec 15, 2006, 07:35 PM
Serg
Thread OP
Mini-HowTo

Solution to jumpy collective and tracking problems with HoneyBee CP2


Hi,

It seems to me that I have found the ultimate solution to the jumpy collective and tracking problems with HoneyBee CP2. I had applied the measures described in the sticky thread but the heli still drifted up and down. Also, stock blades were going out of track regularly.

So, after reading on the Internet I tried the following:
  • Removed the blades.
  • Removed one paddle and removed the flybar from the rotor head set (EK1-0229).
  • Disconnected the links from mixing arms.
  • Removed the top head button.
  • Removed the headset (EK1-0229), flipped it over, and reinstalled.
  • Reinstalled the head button.
  • Turned the blade grips so that the arms would point forward (clockwise from the top).
  • Reconnected the links to the mixing arms.
  • Installed the flybar and paddle.
  • Balanced the flybar.
  • Installed the blades. There was a minor inconvenience associated with this fix: the screws were under the blades.
  • Inverted the value of the pitch percentage in the CCPM mixer (e.g. from 30% to -30%). I use Spektrum and do not know if this is possible with the stock transmitter.
  • Double checked the control movements.
The test hover in the basement showed that jumpiness and/or drift were completely gone and tracking (stock blades) was perfect both on the ground and in flight!

As far as I can understand, turning the grips affected 'Delta three angle' but the theory of this is not clear to me yet. Anyway, this method worked for me.

Best regards,
Sergey
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Dec 15, 2006, 08:58 PM
Registered User
JustPlaneChris's Avatar
Very clever! I'm going to have to try that.

-Chris
Dec 15, 2006, 09:11 PM
Team Mulikow
Gino CP's Avatar
Its possible with the stock Tx. Use reverse servos or swap rear servo connections and flip the aileron rev switch. Then move front servo to the left side using a 7mm spacer block and reorient the arms.
Dec 15, 2006, 11:02 PM
Registered User
Sounds like orc mischief to me!!!
Dec 17, 2006, 10:43 AM
Registered User
JustPlaneChris's Avatar

Brilliant!


Sergey, you are my hero!

I tried swapping things around as you described after fighting another battle with twitchy weird collective response and inconsistent blade tracking again yesterday.

The result? So far so good! Blade tracking is now PERFECT, both with my E-Sky CF blades and some Helidirect 255mm CF blades. Stock woodies still won't track well, but they are an older set that have seen some rough use... probably not a good test.

Best of all, the collective response is much more linear and smooth!

Of course, it may be that the CP2 is just in a good mood today, since sometimes it is a perfect gentleman, and sometimes it's a little -head. Hopefully this change will make it a bit more consistent!

Now I need to pick up some longer 2mm bolts and locknuts so I can just drill out the grips and put the bolts in from the top and have a locknut on the bottom.

-Chris
Dec 17, 2006, 12:45 PM
Registered User
Quote:
Originally Posted by Serg
Hi,
...
As far as I can understand, turning the grips affected 'Delta three angle' but the theory of this is not clear to me yet. Anyway, this method worked for me.

Best regards,
Sergey
If you look at your main rotor, you will notice the main blades are allowed to seesaw by the feathering shaft. If you hold the heli by one blade grip, and hold the heli perfectly level, you will notice the blade grip you are holding has moved up slightly, and the main blades will not be horizontal to the main shaft, but slightly tilted.

If you look at the blade grip, you will notice it has a control ball. When the blade grip tilts up, the side with the control ball will get pulled down a little bit.

If the control ball is on the front, then the front of the blade is pulled down when the blade rises, which decreases pitch. This is good for tracking and smoother collective response, because when the main blade generates a lot of lift, it tilts up, and when it starts to tilt up, the delta-3 angle reduces the pitch if it tilts up too much.

If the control ball is on the back, then the back of the blade is pulled down, which increases pitch. This makes the collective twitchier and more responsive, which is better for 3D.

Most beginner helicopters have the control ball on the front for better tracking and less sensitive collective.

Toshi
Dec 17, 2006, 01:27 PM
Registered User
Aha! which explains why stiffening up the damping of the feathering shaft also reduces the problem.

It's the difference between positive (ball on back) and negative (ball on front) feedback, nicely explained Toshi, thanks.

Once understood it isn't so scary after all

Kim
Dec 17, 2006, 05:26 PM
Serg
Thread OP
Toshi, thank you for the explanation!

Today was one of those rare calm days. So, I went to the park and tried my CP2 in real flight. It flew well: no jumpiness whatsoever. Even if the responsiveness has decreased a bit, it does not matter. I do not expect any 3D from this heli (and from myself for that matter ).

But after practicing on a simulator for some time, I did a couple of stationary (well, almost ) flips for the first time today! And the heli came in one piece from this exercise. But the following attempt of a roll was not as successful. Well, time to order more parts...

Sergey
Dec 19, 2006, 08:23 PM
Registered User
Serg and Toshi:

Thanks for the explanation.

I've been flying with my Honey Bee CP2 like this for 3-4 months. I can verify that it works great. It seems to me the factory should have set it up like this to begin with.

I originally did this to eliminate a "sticky collective" like problem. With the factory configuration, if there is any up and down play in the rotor head or main shaft, then when you apply positive collective, the rotor head moves up slightly which increases the positive collective. This causes the heli to jump up with only a slight application of positive collective.

What I didn't realize was that this modification also fixed my blade tracking problems. In fact I used to have all kinds of problems getting the blades to track. However the tracking problem have been gone for months. Now I know why!

The only disadvantage of this modification is that when I change the blades I have to insert the hex wrench from the bottom.

Is there any way to make this thread sticky or to insert this information prominently in one of the sticky Blade CP / Honey Bee CP2 threads?

Quote:
Originally Posted by Serg
Hi,

It seems to me that I have found the ultimate solution to the jumpy collective and tracking problems with HoneyBee CP2. I had applied the measures described in the sticky thread but the heli still drifted up and down. Also, stock blades were going out of track regularly.

So, after reading on the Internet I tried the following:
  • Removed the blades.
  • Removed one paddle and removed the flybar from the rotor head set (EK1-0229).
  • Disconnected the links from mixing arms.
  • Removed the top head button.
  • Removed the headset (EK1-0229), flipped it over, and reinstalled.
  • Reinstalled the head button.
  • Turned the blade grips so that the arms would point forward (clockwise from the top).
  • Reconnected the links to the mixing arms.
  • Installed the flybar and paddle.
  • Balanced the flybar.
  • Installed the blades. There was a minor inconvenience associated with this fix: the screws were under the blades.
  • Inverted the value of the pitch percentage in the CCPM mixer (e.g. from 30% to -30%). I use Spektrum and do not know if this is possible with the stock transmitter.
  • Double checked the control movements.
The test hover in the basement showed that jumpiness and/or drift were completely gone and tracking (stock blades) was perfect both on the ground and in flight!

As far as I can understand, turning the grips affected 'Delta three angle' but the theory of this is not clear to me yet. Anyway, this method worked for me.

Best regards,
Sergey
Dec 20, 2006, 12:12 AM
I gotta try this one. Sounds like a real fix.
Dec 27, 2006, 09:16 PM
Registered User
This little 'Mod' worked well here! So thanks for that.

I guess it will mean that inverted hovering will now be jumpy instead? lol
Dec 29, 2006, 06:19 PM
Registered User
ndb8fxe's Avatar
I'd like to try this fix, but am a little confused as to what exatly is being switched. Is it just the blade grips? or the center hub also, which doesn't seem likely? Does anyone have other pictures? Can this be done using the stock TX?

Thanks,

Chris L.
Dec 29, 2006, 06:30 PM
Registered User
JustPlaneChris's Avatar
Chris, it cannot be done with the stock transmitter, unless you also switch all the servos to Hitec HS-55's (which rotate in the opposite direction as the E-Sky servos).

The head piece with the mixing arms gets flipped, as do the blade grips, which puts the linkages at the leading edge of the blade instead of the trailing edge.

-Chris
Dec 30, 2006, 06:43 PM
Registered User
ndb8fxe's Avatar
Thanks, After re-reading I kind of figured that.
Dec 31, 2006, 11:06 AM
Registered User
This is the part that you need to install "upside down".


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