To those of you who may be wondering what the horizontal stabiliser on a helo does. The primary purpose of the horizontal stabiliser is to give the helicopter stability in pitch. Both the helicopter rotor and its fuselage have an inherent negative stability derivative in pitch and the stabiliser helps to give the helicopter better overall handling qualities. The large surface area of the fuselage ahead of the centre of gravity has a powerful negative stability influence.
The source material (an oustanding book) is "Principles of Helicopter Aerodynamics" by J. Gordon Leishman (Cambridge Aerospace Series) and a lengthy discussion can be found on page 311 at
http://books.google.com.au/books?hl=...QYYA#PPA311,M1
I would advise caution in the referenced materials use as Angel has not put his seal of approval on it. A poster on another thread put it rather well by saying "I have absolutely no sense of humor when it comes to those who disseminate erroneous information under the guise of being factual. These are understood characteristics in politics. They are dangerous characteristics in engineering." And I might add aviation.
