Has anyone researched or built an aircraft that controls pitch and roll by pumping liquid within the airframe? I am confident I have seen an article couple years ago about a "static surface aircraft" (or at least a concept of it) with no control surfaces, which uses a "wet mass" to adjust its roll and pitch.

The container within its CG is filled with a fluid which is then transferred (or sucked) to the wing tips (to control roll) and along the fuselage (to control pitch). I'm not sure about the yaw control - it should be elevon-like. 



Having spent half a day online, I have been able to only find a DEMON UAV from BAE systems, a "flapless" aircraft which uses flow injection above the control surfaces for maneuvering. That is not the same. 

My question - is there something fundamentally wrong with a concept I have described?
Were there any experimental aircraft made?
The aerodynamic forces resulting from surface deflections are orders of magnitude larger and faster (in their rate of change) than the gravitational forces obtainable by shifting the centre of mass. 

Additionally, as OP seems to realize, yaw control would not be feasible with this method.

So overall it would not be impossible, but it has no clear advantages to outweight the heavy disadvantages. I am also unaware of any prototypes or tech demonstrators using this method.