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

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INTRODUCTION PARAMETERS FOR THE DESIGN OF HIGH- SPEED HYDRAULIC SERVOMOTORS by HAROLD GOLD EDWARD W. OTTO VICTOR L. RANSOM of National Advisory Committee for Aeronautics Lewis Flight Propulsion Laboratory Cleveland, 0. The servomotor dealt Kith in this paper is a power amplifying, positioning device of the type used in such applicatione as control valve positioners, flight controls and power steering devices. The hydraulic servomotor as a device has been known for approximately one hundred years. Its application to high speed machinery, however, appears to be relatively recent. There is consequently very little published literature on the dynamics of *is servomotor in spite of its long history. Nevertheless, when properly designed, the hydraulic servomotor is particularly suited for high speed service because of the extremely high force-mass ratios that can be obtained and because the device inherently is heavily damped. This paper is based on an experimental and analytical study of the dynemics of the hydraulic servomotor recently completed by the authors at Lewis laboratory and soon to be published by the NACA (reference 1) The results of this study have shown that although the response of the servomotor is essentially nonlinear and discontinuous, the response may be closely approximated with relatively simple linear equations. The present paper presents data demonstrating the nonlinear, discontinuous nature of the dynamic response of the servomotor and inqludes a derivation of the baeic analytical expressions for describing the response. The derivations wfiieh are presented in the "Analysis" section of this paper are essentially an abstract of the detailed derivations given in reference 1. The derived analytical expressions are summarized in the form of charts. By means of these charts the rational design of the servomotor to meet specifications on either the transient or the frequency response characteristics is made possible. DEFINITIONS AFSD IKMT& ASSUMET'IONS Straight line servomotor. - The elements of the straight line hydraulic servomotor are shown schematically in f imre 1. In the nkutral position, the spool member of the pilot valve closes the paesages
HYDRAULIC SERVOMOTOR SUPPLY PRESSURE -7 U OUTPUT SHAFT ROTARY HYDRAULIC SERVOMETER PILOT VALVE e INPUT SHAFT OUTPUT SHAFT -597 FIGURE 1
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-3-a'uo#Su!qs~~ MVN 3Hl 4 0 lN3WlIJ
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CONTENTS 1, Centering Charauteristi
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CENTERING CHARACTERISTICS OF POWER
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Since pilqt effort and s*face force
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The centering characteristics excep
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-mtla= etlq 30 pwdo o q m ~APA opl
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HELICOPTER POWERED CONTROL SYSTEM P
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Returning to the discussion of the
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loaded by-pass valve closes, and fr
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FUGET RESEARCH ON FORCE WHEEL CONTR
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precisely. The fir at demonstration
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to hare thq coakpit controle comman
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conrtsnt speed). While this ryrtem
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I I SURFACE I AIRCRAFT DYNAMICS LOA
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AUTOMATIC PUT DYNAMICS a LOAD DISTU
Page 39 and 40: FORCE ME- SERVO. \ - = AMPLIFIER =
Page 41 and 42: The configuration described above r
Page 43: AN ANALYSIS OF FULLY-POWERED AIRCRA
Page 46 and 47: "W@J@tI pendm ao poqtmeard euofenfo
Page 48 and 49: Ooeo red em;Co* ey tg areqm - a d m
Page 50 and 51: Variation of Valve Flcnr with Press
Page 52 and 53: p - instantaneons density (mare per
Page 54 and 55: where %, , %+ , fi , and A r' are p
Page 57 and 58: The error equation (l), with XI * i
Page 61 and 62: C C U P m ZERO - (Bulk Modulus infi
Page 63 and 64: Canparing equation (32) vith eqatio
Page 66 and 67: EFFECT OF ADDRIG A SPEUNC IllbD AT
Page 70: The outtmt 4 is then -tion (a) may
Page 74 and 75: 71 It is of interest to anmine the
Page 77 and 78: It w ill now be shrnm that the quad
Page 79: tp = 4 1' ( 4 include. aU flaxibill
Page 83 and 84: Frequancy Response of Another prore
Page 85 and 86: or, ii the pinton s p w A, in f ~ t
Page 88 and 89: $ - BZ~W~ pfY88WC)* - presstam on e
Page 92 and 93: to the piston. When the spool membe
Page 94 and 95: Figure 2 shows an oscillographlc re
Page 96: lication of equations. - The method
Page 99 and 100: The solution to equation (11) , is
Page 101 and 102: I RATIO OF PEAK TRANSIENT CYLINDER
Page 103 and 104: Equations (21) and (22) are written
Page 105 and 106: variation of this rise time with T
Page 107 and 108: CHART ILLUSTRATING EFFECT OF INERTI
Page 109 and 110: pa lo=$ $8 uoy$eyQd moy pamwam $ndq
Page 111 and 112: IMPROVEMENT OF POWER SURFACE CONTRO
Page 113 and 114: FIG. 2 INSTALLATION - POWER OPERATE
Page 115 and 116: AMPLITUDE RATIO- DB I 0 I 0 I cn 0
Page 117 and 118: The overall reaotien rpring rate ir
Page 119 and 120: FIG.5 - SCHEMATIC -- BASIC TYPE POW
Page 122 and 123: With theae substitutions into equat
Page 124: Although only one type of power oon
Page 127 and 128: 0 AMPLITUDE RATIO- D8 I I I I rU rU
Page 129: In the range ai airplane natural fr
Page 132 and 133: Figure 1. anticipation of the targe
Page 134 and 135: The constant k helped to improve th
Page 137 and 138: to determine if there was behaviora
Page 139 and 140: SYNTHESIS OF FLIGHT CONTROL SYSTEMS
Page 145 and 146:
The hydraulic system itself is a hi
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P :: 7 OT- a- ' 06- 09- . I
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Zeros introduced by resonance of th
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explicit set of specifications-or a
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her@ is to lnake the push-rod as st
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particular problem. We then choose
Page 164 and 165:
changing flight corditions. Idea-,
Page 166 and 167:
A,. Area of bydraullc jack giston.
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