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

Although only one type of power oontrol syrtem has been dieoussed
here, it should be pointed out that the theory of structural
defleotim oompensation applies equally -11 to ans basio
poe itioning sys tom.
Analpis of the system has ahm that the stability of the syrtem
is primarily dependent upon linkage ratios . An evaluatim of a
system for a desired oompensation faotor rill provide an approxiap.ta
value for the required linkage ratio. In an aotual installation,
it may be diffioult to aocurately determine the spring rates of
the system, and tests mry be required to obtain the best liPkopp
ratio as governed by desired symtem perf onmnoe. This prooedure
was used in arriving at the optimum linkage ratio for the installation
disoussed in this paper.
A diagrwtio sketoh of the basio pwer control system with tho
addition of the oanpensated linkage ie ahom in Figure 6. In tb
aotual inrtallation as rhom in figure 7 it was neoessary to add
five links to the original eystem. The nwnber of links required
is prila~rily omtrolled by the physioal location of oaapmenta in
the system. The applicati~n of this type linkage into a.sy8t.m
already designed may be mere difficult than for a new system whioh
oan be designed to inolude the simplest and most effeotive
arrangemnt.
The improvement in st+bility of this system rith ths addition of
tho ompensating linkage permitted use of a higher gain valve with
a nearly linear flow versus diaplaoement oharaoteristio. This
resulted .in a higher performance system for all amplituder. The
value of the canpensation faotor for this system as installed in
the airplane was approdmately 1.1.
The degree of imprmmnt of the actual airplane installation is
shm in figure 8. This is a representation of the power oontrol
syatem performance'. It can be seen that the phase ohraoterirtior
of the rptem have been improved oonsiderab2y war the uuo0mpenaat.d
syrtem as shown in figure 3. For better oomparison, figures 3 md
8 are both shom in figure 9. It rhould be noted that the
amplitude at whioh the oolapensated system was tarted 1.8 only
fl/L degree as oompand te tl-l/LO for the morpluated ry.tem.
This to ahow e m more the degree of imprmunt whish
ma obtained, a8 the reapse of a system pnemlly beeomor
poorer rith a deorease in amplitude.