"Natural" COG & Energy Efficiency Relationship

janoots2

Member
There are a million threads out there about how to find your COG....this isn't one.
I couldn't find much on the benefits of building your copter with the intent of aligning the vertical COG so it aligns with the propeller plane naturally.

I think horizontal COG is easier to understand - you should try to build your craft perfectly balanced at the center and I would like to believe that most rigs are at built at least close. If it's off center, whatever arm the weight is closest to will need to use more energy to compensate for that weight. However, if the opposite side doesn't need to use as much energy, does the total energy usage even out?

Same idea with vertical COG, but I think more opportunity could lie here as there is more weight typically at stake here. For instance, I used to fly my rig with the battery on the underside of my frame which, along with my camera and gimbal, made my COG very low. But I figure it has to take much more energy to not necessarily tilt the craft, but hold that tilt when the vertical COG is either higher or lower than the propeller plane.

For example, with the intent of holding a broomstick level horizontally it takes much LESS energy to hold it in the middle and much more to keep it level by holding it closer to one end.

Holding it level vertically, is easy. You can hold it anywhere and keep it perfectly straight up and down without exerting any extra energy. This would simulate a hover. BUT, hold that broom stick toward one end, tilt it and hold that tilt. You use much MORE energy the further you get away from the middle, or move COG off center. Hold it in the center, tilt and hold and the energy used is much less.

So now that I have redesigned by hexa with the battery on top rather than the bottom, bringing my COG closer in line with my prop plane - should I expect my battery efficiency to increase?

Or do I think too much.... :stupid:

View attachment 10066
 

Attachments

  • Cutout 1.jpg
    Cutout 1.jpg
    123.9 KB · Views: 200
Last edited by a moderator:

kloner

Aerial DP
in fff flight like for fpv, beause we fly around 45 degrees alot we like the battery as close to inside the frame as possible, it keeps the tilt from changing cg so much as if you put it top or bottom of the frame. with packs on top the farther forward you lean, the further forward cg will move which is if enough weight to counter the gimbal, is a similar deal,,,, putting all the weight at the bottom makes it sluggish and a more controlled feel but like the e-brake got left on. on top can make it a sketchier ride depending how much weights were talking
 

janoots2

Member
I know what you mean about it feeling sluggish and the e-brake being on with the COG very low, that's actually one of the reasones I changed to the battery on the top. I flew fine and steady, but could tell the weight was affecting it. Now my COG is still vertically low, but not nearly as much and I'm hoping I found a nice medium. Looking forward to flying this weekend to test it.
 

janoots2

Member
Just as a follow up, I did not gain flight time with designing the vertical COG in line with the prop plane nor did I lose any.
 
Last edited by a moderator:

Top