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

By way of introduction to this problm, I wauld like to revert for
a momsnt to some of the ideas expressed in the axcellent papr we heard
on Tuesdey rnornbg by Mr. Andrm of Hughes Aircraft and presmted bgT
Mr. Turner. In this paper it was rather forcibly pointed out that we
are rapidly rea- the point where we must design our porn boo&
control system to meet quantitative speclfioatiom concerning both
stability and control. I like to think of the situation in something
like the foIloving light, with a very s-6 analogp. I picture the w
control system designer in a position somewhat analog~ls to a &ernyew
old boy in a baseball game. An the game start@, the other bags are
all under ten years old; the mere presepce of our slxtem-year old is emougb .
to throw fear into the opposition, Just es in the early years of pmr boost
system, the mere presence of the control wet= desiepar and a little
imaginetion on his part solved the problems. As the game plogresses, however,
older boys arrive. Our aixtegt-year-old has to work to get his base hits.
He begha to look amuad for a better bat and tools; he starts to consider
using a little stratem instead of the previous brute-fome tactics. In an
analogous manner, the control systems engineer starts to adopt same of the
servomechanism theorg--the use of Nyquist diagrams that have been mentioned
several times here during the past few days, for axample. BLlt unfortunately,
the game has not yet stabWed. For, approaching our ballfield are a half
dozm professioaal ball players, eager to get into the game. Our sMemyear
old is wing to have to call on all his ability if he is to hold his
own. In our inmediate problm, we see these professional ball players as
the problems associated with our planes flying at a Mach number of &5.
If we are to design successflrl power-boost aystams and tactically-capable
aircraft operating at these high speeds, it seerme imperative td us at Purdue
that all available knowledge be brought to bear on the problem. We feel
that in a few years, when we are confronted
-
with the design of the power
boost systems for these high-speed aircrafb, there will be no accuse for
us not h a m a understanding of the problem and a general idea of a suitable
approach to the aolut ions.
What specifically are the problems associated with the design of a highperformance
power-boost wstem? Thw are in number. We wish to mention
only a few of them today in any detail. The problem we have heard most about
at this meeting is the design of an appropriate artificial feel system. I
feel, howemr, tinat this is only one of the basic problems. It has received
considerable attention here during the past few days principally +cause it
is a problem which is already confronting the engineer. Of a perhaps !laore c
basic nature, however, are the twin problem of stability and control. Indeed,
the satisfactory solution of the artificial feel problm can only be arrived
at in conjunction with at least partial solutions to the stability and control -
problems, for the artificial feel system is an integral part of the overall
loop which does determine both the relative stability and the control charact'eristics
.
What essentially are the problems associated with control and stability?
The most pressing problem, it seams to me, is the development of a more