be used with any length blade and can be used in conjunction with other control devices such as the vented blades of the first aspect of this invention referring now to fig5 9c one sees the third aspect of the invention in particular fig5 illustrates blade or foil 30 with a fixed leading edge 32 trailing undulated portion 34 is attached to fixed leading edge 32 by hinge 36 the angle of trailing undulated portion 34 is adjusted by vertical elevator 38 the design of fig5 has the advantage that the position of the leading edge 32 is fixed and variation of the angle of trailing undulated portion 34 does not raise or lower fixed leading edge 32 fig6 illustrates a similar design to fig5 blade or foil 30 is a one piece design the portion of blade 30 proximate to leading edge 32 39 is coupled to support 36 which could be fixed or a vertical elevator while trailing edge 40 of foil 30 is supported by vertical elevator 38 alternately support 36 could be a vertical elevator and support 38 could be fixed typically blade 30 rests on fixed support 36 so as to allow a change of angle of blade 30 with respect to fixed support 36 as trailing edge is raised and lowered by vertical elevator 38 however a variation.