View Full Version : CG ECO 8
This might be a daft question, but where is the cg of the ECO 8, and how should it be set up.
I assume when holding the main rotor shaft, the heli should hang perfectly in the centre?
To acheive this, I have to literally hang the battery right in front, almost fallling out, and being held in place by the body.
Yes, this is a problem. I actually had my CG a 10 mm or so behind the rotor mast. To get it in place I have my 10 cell battery packs as far forward as possible without letting them fall out of the rear holder. I fly with 1000 mAh packs as well as 2400 mAh packs. The lighter packs give a CG to the rear as described above.
If you build the CCPM version and (even worse) put your tail servo on the boom. The CG will be far away behind the rotor mast.
On my Eco 8, I have at rear of the mast:
-the tail rotor servo (really far)
-two servo of the cyclic
and in front:
-the last cyclic servo
-the speed controller.
In order to hold the battery forward, I have build a kind of "Inverted-U" support made out of 4mm circuitboard. This support is placed at the front of the Eco8 where you have in the frame a "teeth" with a 2mm hole at the base. I screw the support there. I also made two supplementary holes near the top of these teeth to also fix my support at the top to to avoid tilting. (On other websites, I have seen people using the two teeth to keep a rubber bracelet to hold the battery. it's the keep it simple way.)
With my solution, the battery is held by my support and the first holder on the undercarriage (the front one, I use 8 cells battery). I have used the O-ring of the rear on my support.
With this installation, my canopy has to be fixed a little more forward that on the original settings. ( 1cm )
The battery is hold safe in place aand the CG is a little in front of the rotor mast as required by the user manual settings.
Choose your own way ...
I have had this problem also, given the weight of the 3000 Sanyo cells (x10), I can only get the correct CG (with the main mast vertical held by the flybar) by swinging the pack all the way forward and moving the canopy forward also.
I haven't tried the rearward CG but with it where it is have no problems.
Another way to check out the CG is to hold the head firmly by the blade holders, and tilt the heli through 90 degrees (as if in knife edge flight) if the tail drops then you have a rearward CG, if the nose drops you have a forward CG, if it don't move from the entry position, you have the 'correct' CG.
The 'correct' CG is pretty debatable as many people prefer to have it slightly forward and others exactly on the dead centre. The 'gas' guys can rarely hit it right on the button as we can due to the changes in fuel levels (unless they have the tank slung directly under the main mast) through the flight so I would advise you 'try' it out at different positions and settle on whichever suits you style of flying the best....
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