Are there any references to the Vuichard technique in particular how\why it is suppose to work?
The only reference I could find googling is the wikipedia article (or direct quotations from it), and let's face it neither wikipedia (nor anonymous forum posts!) are necessarily reliable sources of information.
The wikipedia article suggests the technique is described in the 2013 R22\R44 Flight Training Guide (which looks like it is only available in hard copy from Robinson).
Matthew