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

A desirable faatan of any well designed hydraulic aatrretor
installation is that the piston and mounting structure are a8 righi a8
porsible. Normally, then, the piston spring constant 18 large acupared
to all other spring aonstants, including that of the hydraulia fluld.
With this important asmnnption, the quadratic (;*G sa 44 ++Js
+S]
becanes an appmxbate factor of the numerator and denaninator of the
4+
portion of oquation (55), reducing it to:
/A+ +
Vary little more can be done to slnpUfy the above arprersion;
actual values of the constants mast be substituted and the s3q,resrion
nmuerically factored, Experience with typical Uorthmp-typo WrauUc
sptans, howover, bas shoun that the den-tor cubic has gn appnudYte
quadratic factor,
(4sa+4sf 4 +I) j ; this im lies that
the constant , is rn). large (1.e.. G ia very -7, uuch 18
the case for valve positions near neutral. Thus,
The term in the braces, to reiterate, is the cornctive tea uhiah
must be added to (or mubtracted inn) the quadratic, f#= sa+4 s
the ae-c
+AG) , to obtain the proper transfer function bet-
force, F , and the corresponding surface deflection, Xs . Thir
corrective tern is of the form,