condition of control trajectory, while the latter is the inherent characteristic of
the selected steering gear. The deflection speed of control surface is usually
related to missile aerodynamic configuration. The duck rudder (e.g., French
rattlesnake) is lower, the normal rudder (e.g., Sam 2) and the tail rudder (e.g.,
patriots and standards) are moderate, and the full-motion wing (e.g., sparrows
and Aspide) is higher. In fact, for the linearized missile control body, the first
thing is to limit the rolling angle of the missile, requiring the aileron steering
gear of the rolling loop to have a higher speed. In order to ensure the change
rate of missile maneuvering overload, the steering gear of pitch and yaw loop
should also have proper speed. In general, yaw speed is lower than pitch
speed. If the independent aileron rudder with the electric differential scheme is
adopted, the yaw speed can also be satisfied when the pitching speed of the
rudder is guaranteed. The problem is that the load speed should be allowed to
drop more than the no-load speed, even if the patriot’s steering gear, its load
speed is only about one-seventh of the no-load speed. Of course, for those with
special requirements, the rudder deflection speed cannot be arbitrarily reduced.
(7) The load moment of the control surface (including rudder and aileron) depends
on the maximum velocity pressure on the control trajectory, the aerodynamic
configuration of the missile, the maximum angle of attack, and the maximum
comprehensive deflection angle of the control surface. The maximum flying
velocity pressure is determined by the maximum Mach number and the
minimum flying altitude of the missile. The aerodynamic layout of missile
directly determines the equivalent area of the control surface and the position
of the spindle (i.e., the force arm between the aerodynamic pressure center and
the spindle). The maximum angle of attack and rudder deflection are determined by the maximum allowable overload of the missile. In order to reduce
the hinge moment of the control surface, the full-motion wing is not used as
far as possible, but the combined duck rudder, such as the French Rattlesnake,
is preferred. Or, as Patriots do, allow greater anti-manipulation. The combined
duck rudder not only has a small equivalent area, but also the aerodynamic
pressure center varies very little with the missile’s flight speed. Therefore, the
hinge moment on the rudder surface is very small, and the hydraulic and
electric rudders with strong counter-maneuverability are allowed to have larger counter-maneuvering moment. That is to change the polarity and size of
the acting arm and minimize the maximum positive control moment. In the
case of patriots, the ratio of positive and negative control torques is about 5:4,
as shown in Fig. 9.11.
(8) The comprehensive deflection angle of control surface (including rudder and
aileron) depends on the maximum allowable rudder deflection angle and the
equivalent maximum aileron deflection angle. The former is limited by the
maximum allowable overload of controlled trajectory, and the latter is determined by the maximum allowable interference of rolling circuit. Whether
using mechanical or electrical differential, whether using push–pull or push–
push steering engine, the comprehensive deflection angle of the control surface cannot be too large, generally in the range of 20 $ 30
, especially the
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
81
the selected steering gear. The deflection speed of control surface is usually
related to missile aerodynamic configuration. The duck rudder (e.g., French
rattlesnake) is lower, the normal rudder (e.g., Sam 2) and the tail rudder (e.g.,
patriots and standards) are moderate, and the full-motion wing (e.g., sparrows
and Aspide) is higher. In fact, for the linearized missile control body, the first
thing is to limit the rolling angle of the missile, requiring the aileron steering
gear of the rolling loop to have a higher speed. In order to ensure the change
rate of missile maneuvering overload, the steering gear of pitch and yaw loop
should also have proper speed. In general, yaw speed is lower than pitch
speed. If the independent aileron rudder with the electric differential scheme is
adopted, the yaw speed can also be satisfied when the pitching speed of the
rudder is guaranteed. The problem is that the load speed should be allowed to
drop more than the no-load speed, even if the patriot’s steering gear, its load
speed is only about one-seventh of the no-load speed. Of course, for those with
special requirements, the rudder deflection speed cannot be arbitrarily reduced.
(7) The load moment of the control surface (including rudder and aileron) depends
on the maximum velocity pressure on the control trajectory, the aerodynamic
configuration of the missile, the maximum angle of attack, and the maximum
comprehensive deflection angle of the control surface. The maximum flying
velocity pressure is determined by the maximum Mach number and the
minimum flying altitude of the missile. The aerodynamic layout of missile
directly determines the equivalent area of the control surface and the position
of the spindle (i.e., the force arm between the aerodynamic pressure center and
the spindle). The maximum angle of attack and rudder deflection are determined by the maximum allowable overload of the missile. In order to reduce
the hinge moment of the control surface, the full-motion wing is not used as
far as possible, but the combined duck rudder, such as the French Rattlesnake,
is preferred. Or, as Patriots do, allow greater anti-manipulation. The combined
duck rudder not only has a small equivalent area, but also the aerodynamic
pressure center varies very little with the missile’s flight speed. Therefore, the
hinge moment on the rudder surface is very small, and the hydraulic and
electric rudders with strong counter-maneuverability are allowed to have larger counter-maneuvering moment. That is to change the polarity and size of
the acting arm and minimize the maximum positive control moment. In the
case of patriots, the ratio of positive and negative control torques is about 5:4,
as shown in Fig. 9.11.
(8) The comprehensive deflection angle of control surface (including rudder and
aileron) depends on the maximum allowable rudder deflection angle and the
equivalent maximum aileron deflection angle. The former is limited by the
maximum allowable overload of controlled trajectory, and the latter is determined by the maximum allowable interference of rolling circuit. Whether
using mechanical or electrical differential, whether using push–pull or push–
push steering engine, the comprehensive deflection angle of the control surface cannot be too large, generally in the range of 20 $ 30
, especially the
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
81