Bevor ich das jetzt übersetze, voila:
EP (Avidyne's Envelope Protection) is a unique and
proprietary Avidyne autopilot feature which prevents the pilot from
commanding the autopilot to stall or overspeed the aircraft.
The term “Flight Envelope” normally
implies airspeed and altitude but the system is significantly more
capable than that. While indicated airspeed limits are met by our EP,
neither the aircraft’s safe operating range, nor Avidyne’s autopilot
protections, are that simple.
EP monitors and limits the instantaneous lift demand
on the aircraft. It is active in both Autopilot Engaged and Flight
Director modes. Lift is constrained by saturating pitch rate command to
the maximum value that will not exceed the wing g loading such that the
sum of kinematic and (projected) gravitational g load remain within 90%
of the maximum available. The available lift calculation is sensitive to
flaps, speed brakes, weight, temperature, speed, and incorporate
margins purposely designed to mitigate ice.
The term “kinematic g” takes into
account the turning of the aircraft’s velocity vector. Any attitude
whatsoever is automatically mathematically incorporated by this method.
Next, gravity is vectorially added to the lift demand to the extent it
projects on the wing normal.
Thus, the autopilot knows how much g is needed to
maintain level turn or constant climb rate at any attitude, and that g
request is “fed forward” into the control loop request before it even
can generate a loop error. This means that the lift demand is pre-biased
to account for the extra wing loading needed in turns. As an example,
at 75 deg bank, the starting point for g request from the pitch inner
loop is 3.9g. This is then augmented by any control loop tracking error
(the closed loop part of the autopilot) and then limited (if necessary)
by EP.
Last, pitch rate is the “lever” by
which the EP is implemented. By imagining flight through a zero-g
pushover, it is possible to see that EP can arbitrarily constrain lift
demand by modulating pitch rate: a steady “push” holds lift to zero.
This is exactly how the autopilot works. Besides being “all attitude”
capable, this method additionally has the collateral consequence of
controlling steady level flight to 1.1Vstall. In turning flight, a
higher speed will result, but it’s all implemented naturally through
pitch rate. The significant principal benefit is that EP acts with all
the bandwidth (speed of response) of the pitch rate control loop, which
is the most reactive and capable loop in any autopilot, and limited only
by servo performance. Speed or attitude controls (such as used by
others) are in comparison relatively ineffectual. This implementation
allows EP to respond successfully to all but the most severe initial
conditions avoiding stall in almost any circumstance. While override is
always at the pilot’s discretion, all modes, including Straight and
Level and Flight Director, are envelope protected.
