羡慕楼主有机会坐上双水獭。你提到的涡桨反推原理我找了一段FAA的资料直接COPY下来,相信你看得懂,里面也讲到了操纵方式:
The thrust that a propeller provides is a function of the angle
of attack (AOA) at which the air strikes the blades, and the
speed at which this occurs. The AOA varies with the pitch
angle of the propeller.
So called “flat pitch” is the blade position offering minimum
resistance to rotation and no net thrust for moving the
airplane. Forward pitch produces forward thrust—higher
pitch angles being required at higher airplane speeds.
The “feathered” position is the highest pitch angle obtainable.
[Figure 14-8] The feathered position produces no forward
thrust. The propeller is generally placed in feather only in
case of in-flight engine failure to minimize drag and prevent
the air from using the propeller as a turbine.
In the “reverse” pitch position, the engine/propeller turns in
the same direction as in the normal (forward) pitch position,
but the propeller blade angle is positioned to the other side of
flat pitch. [Figure 14-8] In reverse pitch, air is pushed away
from the airplane rather than being drawn over it. Reverse
pitch results in braking action, rather than forward thrust
of the airplane. It is used for backing away from obstacles
when taxiing, controlling taxi speed, or to aid in bringing the
airplane to a stop during the landing roll. Reverse pitch does
not mean reverse rotation of the engine. The engine delivers
power just the same, no matter which side of flat pitch the
propeller blades are positioned.
With a turboprop engine, in order to obtain enough power
for flight, the power lever is placed somewhere between
flight idle (in some engines referred to as “high idle”) and
maximum. The power lever directs signals to a fuel control
unit to manually select fuel. The propeller governor selects
the propeller pitch needed to keep the propeller/engine
on speed. This is referred to as the propeller governing or
“alpha” mode of operation. When positioned aft of flight
idle, however, the power lever directly controls propeller
blade angle. This is known as the “beta” range of operation.
The beta range of operation consists of power lever positions
from flight idle to maximum reverse. Beginning at power
lever positions just aft of flight idle, propeller blade pitch
angles become progressively flatter with aft movement of
the power lever until they go beyond maximum flat pitch
and into negative pitch, resulting in reverse thrust. While in a
fixed shaft/constant-speed engine, the engine speed remains
largely unchanged as the propeller blade angles achieve
their negative values. On the split shaft PT-6 engine, as the
negative 5° position is reached, further aft movement of the
power lever also results in a progressive increase in engine
(N1) rpm until a maximum value of about negative 11° of
blade angle and 85 percent N1 are achieved.
Operating in the beta range and/or with reverse thrust
requires specific techniques and procedures depending on the
particular airplane make and model. There are also specific
engine parameters and limitations for operations within
this area that must be adhered to. It is essential that a pilot
transitioning to turboprop airplanes become knowledgeable
and proficient in these areas, which are unique to turbineengine powered airplanes.