Summary
As part of a project to design a small hydro-eletric plant for use by isolated riverside dwellers three low cost rotors were constructed: (1) an axial-flow turbine constructed of local timber, (2) a Savonius rotor made out of a modified oil-drum, (3) a floating undershot water-wheel. Each rotor was tested in a frame attached to the side of a boat. The power output, starting torque and maximum speed of rotation were measured. The rotors were compared in their power output per unit area of submerged profile, weight, ease of construction, scale-up potential, maintenance requirements, ability to cope with driftwood and cost. The axial-flow turbine gave the highest measured power output, 40 watts per m2 at a water speed of 0,84 m.s-1, the speed of the rio Solimões near to Manaus. Prospects for the use of such rotors are discussed.