Autos: To drop, or not to drop
Join Date: Dec 2001
Location: Philadelphia PA
Age: 73
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Ascend Charlie:
The reason the S-76B probably doesn't have a low altitude, high speed portion of the HV curve is that most people realize it is a silly piece of information.
On the S-76A and many other older helicopters that area of the curve probably a hold-over from the US Military HV thinking that required a two second delay on all controls before reacting. The civil requirement for the upper portion is a one second delay on the collective only - no delay necessary for pedals and cyclic. Why the difference?
The civil authorities were convinced (rightly or wrongly) that the pilot might have his hand off the collective (hence the delay there) but most certainly would have hands on cyclic and feet on pedals. The same logic has now been applied to the low height, high speed area of the curve - anyone who is at that height and speed had better have hands on collective and cyclic (and feet on pedals) and would react immediately and instinctively to a failure- in fact probably react faster to the aircraft response than to any indication of failure.
It's ignored now in newer helicopter certifications.
The reason the S-76B probably doesn't have a low altitude, high speed portion of the HV curve is that most people realize it is a silly piece of information.
On the S-76A and many other older helicopters that area of the curve probably a hold-over from the US Military HV thinking that required a two second delay on all controls before reacting. The civil requirement for the upper portion is a one second delay on the collective only - no delay necessary for pedals and cyclic. Why the difference?
The civil authorities were convinced (rightly or wrongly) that the pilot might have his hand off the collective (hence the delay there) but most certainly would have hands on cyclic and feet on pedals. The same logic has now been applied to the low height, high speed area of the curve - anyone who is at that height and speed had better have hands on collective and cyclic (and feet on pedals) and would react immediately and instinctively to a failure- in fact probably react faster to the aircraft response than to any indication of failure.
It's ignored now in newer helicopter certifications.
Paco is correct in that the Gazelle entry to auto at low level and IPS (intermediate pitch setting, 13.5 degrees at about 125 kts) was to zoom climb leading with cyclic and retaining sufficient collective to maintain Nr. The manoeuvre would give 2 to 300 feet extra altitude before a gentle nose over selected the 60 kts auto speed. The extra height gained meant that instead of the field ahead, you had more options in selecting your field and turning into wind.
