[cycry04]

I just built a top-notch S500 using a Revolution board, OPlink, and Mini Ublox Neo-6M GPS that I got from Banggood. The quadcopter flies great when NOT using any type of GPS and the Attitude Estimation Algoritmh is set to Basic, but as when I change the Attitude Estimation Algoritmh to INS13GPS and set everything else up for Position Hold, the quadcopter tips over when I try to take off.

I have no idea what could be the problem. Anybody have any ideas???

[f5soh]

Hi, welcome.

You should calibrate sensors correctly, see here:
https://librepilot.atlassian.net/wiki/display/LPDOC/Advanced+features

All alarms in SystemHealth should be Green, all time.
Also consider using only the onboard Mag is very difficult and your setup should be magnetic perturbation free: twist all power wires for example.

CC3D and Revolution are two different boards, taking both names as same board name do not make sense. Or only for Chinese vendors.

[TheOtherCliff]

You should never try to take off in PositionHold.  What happens is that the GPS drifts a little and it tries to move sideways while still on the ground.

Take off in Attitude mode and switch to PH, or better yet, skip PH and use VelocityRoam which is the same as PH when the sticks are centered.