W_ocker,
You are correct to say that the best angle of climb speed is zero knots BUT only if the aircraft can hover OGE or better. For a limited power situation (where there is no OGE hover) there has to be another "best angle" climb speed.
This "limited power" best angle of climb speed will occur for the best rate of climb for the smallest increase in airspeed above zero knots.
I have just searched all my old notes; unfortunately I can't find the diagram I thought I had showing this and Prouty's Aerodynamics books don't seem to mention it at all. However, I think it occurs on the "Power required / Airspeed" graph where a line from the origin meets a tangent to the curve at right angles. Obviously this is quite a bit slower than the best rate of climb speed (where a line from the origin touches the curve at a tangent). Probably difficult to visualise, just draw yourself the bucket curve on a piece of paper.
Without thinking too deeply (as I am suffering from a cold
) this is reflected in 'Perf. A' technique where in the event of engine failure after CDP at V1, V2 is held until clear of obstructions (best angle?) and then the aircraft is accelerated to Vy (for best rate) of climb.
V2 is variable but about 50 kts on the S-76. I'm not 100% certain that V2 is actually best angle of dangle per se. Will research a bit more!
