Report of the Second Piloted Aircraft Flight Control System - Acgsc.org

C C U P m ZERO - (Bulk Modulus infinite,) For the
limit- case in which the qmpressibility of the fluid beomes vem
mall, the laop transfer fuuction becanes:
huad the neutral position, with 5 = 0
, the open
loop transfer fuuction reduces to a very simple expression.
Equation (28) will be recognized as the conventional expression used in
the analpis of -radio amplifiers when used with mechanisms b a a
large lags at fmquancies mch lower than those of the wraulie amplifier.
Epuation (28) is also recognized as that of perfect iategrator ad zem
podtion error servo, The reason for this is, of course, tbat. in thir
care there are no spring or friction loads. If the l@raulic amplifier
itself is ntable, thin approximation is an excellent one when the other
elanants of a control loop ouch as an autopilot and airframe sene to
lovrr the possible gain cmsaover frequency, & = cg /A . For
une In such analpen, than, the hydraulic system is adequately dencrlbd
am
-
The tima constant is capable of being made quite mil with
proper derQn, down to the order of v100 second in the authorsf emprlmcen.
C~~IBILITT INFINITE (~ullc Ibiulus zero:) If valve damping,
Bw Tbetween the valve spool and the valve housing), is included an
an extension to the simplified load systeu, the open loop transfer function,
equation (25). can be- nbrmr to be