Inflated Membrane Structures on the Ground,in the Air and in Space 217 Fig.7.Inflated roof with pressure chamber [7] Fig.8.High altitude balloon [8] at mean sea level.The buoyancy is a natural energy potential.Its activation needs no energy.Nevertheless the potential for "flying structures"seems to be not fully explored yet. The classical example is the high altitude balloon.It can be seen from Fig.8, that in this case the shape depends on the expansion of the buoyancy gas,which expands when the outside air density diminishes during the ascent. If the shape of the body should be kept constant at all altitudes,e.g.for aerody- namic drag reasons,a ballonet-technique can be used,see Fig.9.Inside the body air inflated balloons are placed,which release their volume to the outside in the sameInflated Membrane Structures on the Ground, in the Air and in Space 217 Fig. 7. Inflated roof with pressure chamber [7] Fig. 8. High altitude balloon [8] at mean sea level. The buoyancy is a natural energy potential. Its activation needs no energy. Nevertheless the potential for “flying structures” seems to be not fully explored yet. The classical example is the high altitude balloon. It can be seen from Fig. 8, that in this case the shape depends on the expansion of the buoyancy gas, which expands when the outside air density diminishes during the ascent. If the shape of the body should be kept constant at all altitudes, e.g. for aerody￾namic drag reasons, a ballonet-technique can be used, see Fig. 9. Inside the body air inflated balloons are placed, which release their volume to the outside in the same