CG on a Vulcan Mantis 900 Hexa

[RoryG]

Hi All,

I've just completed building a Vulcan Mantis 900 Hexa in V hex configuration with two Z arms. Initially she'll be carrying a GoPro and H3-3D mounted on a quick release gimbal plate at the front. My dual batteries are side mounted so in this configuration she's very nose heavy.

I do a lot of RC fixed wing and glider flying and it's common practice to add weights to achieve the correct CG. By adding 4oz (113g) to each of the rear arms under the motors I can achieve perfect balance - is it better to add this extra weight to balance or let the FC sort it out? My other option is a rear mounted battery tray but that would likely give me the opposite problem and make it aft heavy. Any suggestions appreciated!

 

[Old Man]

Looks good and the frame also permits later expansion for more lift capability. Well done.

The take off a lot better when balanced. With the CG in the wrong place they can lean pretty hard in the opposite direction when lifting off. Could you move a battery to the gimbal rack to compensate?

 

[RoryG]

Yes, the plan is to fit lower Kv motors, retracts and a Z15 at a later date, and up from 4S to 6S (the ESCs are 40A and will handle 6S). The current setup will suit me fine for a while though.

If I mount the batteries at the rear then she's tail heavy, the batteries would need to be somewhere around the rear landing gear mount to achieve balance and they would be difficult to fix. The side mounts are easy to access and allow for a quick battery change.

She weighs just under 4.5kg, so adding an extra 226g should not make a lot of difference to flight times, just wondering if it was common practice with multis.

Cheers,

Rory

 

[Old Man]

The more enlightened will do what it takes to balance correctly. The others will post at another site complaining of tilting at launch. My view is add the weight, perhaps make it useful in the form of antennas, Vtx, or FPV battery.


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