A Geometric Characterization of Helicodial Surfaces of Constant Mean Curvature
Publications de l'Institut Mathématique, (N.S.) 43 (1988) no. 57.

Voir la notice de l'article dans eLibrary of Mathematical Institute of the Serbian Academy of Sciences and Arts

We prove that a helicodial surface has constant mean curvature if and only if its principal axes make an angle constant with the orbits. Moreover, the arguments used lead to a simple proof of the fact that all helicodial surfaces with constant mean curvature $H$ can be isometrically deformed, trough helicodial surfaces of the same $H$, into surfaces of revolution of the same $H$ (Delaunay surfaces). 
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     author = {Ioannis M. Roussos},
     title = {A {Geometric} {Characterization} of {Helicodial} {Surfaces} of {Constant} {Mean} {Curvature}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {137 - 142},
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     volume = {(N.S.) 43},
     number = {57},
     year = {1988},
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Ioannis M. Roussos. A Geometric Characterization of Helicodial Surfaces of Constant Mean Curvature. Publications de l'Institut Mathématique, (N.S.) 43 (1988) no. 57. https://geodesic-test.mathdoc.fr/item/PIM_1988_N_S_43_57_a16/