power loss i think?

[jeffg]

hello FPV community< i am at a loss. so ive built a freestyle quad but have other RTF quads as well and the same is happening with them.
so the issue is when i olug in evrything seems fine i get all my beeps it cams good, vtx is good checked all solder points evrything seems in tune but after take off i have great thrust to start but then i start to descend then gradually get no stick input. when i land and unarm i still have all my lights and i can arm and take off but still dowes the same thing if anyone out there has any clue as to what my problem might be would be greatly appreciated

 

[Fast and Curious]

How long does it take to happen?
If it happens when you were far away it could be just losing signal when getting close to the ground. Also your battery could be low, do you have something on the quad to tell you when the battery reaches 3.5 volts.