SERVO/SURFACE ACTUATOR CONFIGURATION STUDY

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP71B00265R000200130004-1
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 18
• Document Creation Date: December 23, 2016
• Document Release Date: November 21, 2013
• Sequence Number: 4
• Publication Date: January 1, 1960
• Content Type: MISC

Declassified and Approved For Release 2013/11/21 : CIA-RDP71600265R000200130004-1
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SERVO/SURFACE ACTUATOR,
-CONFIGURATION STUDY
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So PREMISS OF STUD/
Ao Three AriS Stability Aufgaentation is required to fly the vehicle
during most if not all of its mission.
Bo It is desirable to stay within the state of the art and use proven
techniques wherever possible consonant with other requirements.
G. The following trade-off criteria has been considered as a guide:
Ur.
Performance
15
Pailsafety
20
Mission Success
30
Maintainability
5
ccst 10
tieight
20
100
11. GROSS CONSIDERATIONS
A. Side Electric Stick vs. Side Electric Stick plus Mechanical Baak-Up
1. The airframe has stated that the vehicle must have a fail-
operational SAS because SAS is needed in order for the
? pilot to be able to control the vehicle over a large portion
of its mission.
? 2. This being the case, it becomes hard to justify a mechwical
back-up system since the ffechanical back-up can not be used (raga
without ,,41, and:
720 150 .? 250 pounds of weight could be eliminated.
b. Trim wheels and triple pick-offs replace non-redundant
bulky trim actuators.
c. The X-20 did not have a manual mechanical system.
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A)
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d. The YF-12 SAS has been more reliable in actual usage
than the manual control system.
e.: We can eliminate ?linkage problems associated with cock-
pit raising.
f.: Gear shifts, mixers,, ate., can be 'eliminated..
B. Parallel vs. Series Sertos,
lw If we use a parallel 'eerie, it mutt be located near the cock-
_
pit 'so that its disengaged friction will not adversely affect
the break-out force of the center stielf.:7-Tliii then.mernii
long cable run aft to the surfaces. :This in turn will result
In additional undesirable non-linear dynatics between the SAS
and the siirfade. This could result in additional surface
activity and vehicle motion which IS Undesirable considering
the type of payloa&
2?.? In addition, ueing only a parallel servo will result in short
peribd damping corrections being reflected at the center stick.,
3. Operation of the triple Stability Augmentation Systein through
single methanical system control linkages; gear shift and mixer
not only degrades the probability of mission success to some
extent but makes it possible for a single failure in the
mechanical back-up to be catastrophic.
C. Electronic vs. Hydraulic Voting of Servos
The YF-12 and the 5R71 use electronic majority voting of redundant
servos based on servo position. This scheme is fail operational
for first failure and failsafe for a second failure with pilot
option for re-cycling. There has not been a "system" failure
to date with this system in thousands of flight hours.
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C. (contld)
The Frill uses a detectionroorrection scheme of hydraulic voting
as contrasted to hydraulic majority voting. Although this scheme
does not offer as good a.reliability as a hydraulic majority.
voting. scheme, it weighs less and may offer pilot indication in
a simple manner.
Inherently, the hydraulic scheme has the advantage of less dynamic
lag in the voting because it doesn't need to wait for the output
ram to integrate into position. However, in the electronic scheme
Of voting there is more flexibility in the adjustment of allow-
able system errors and thus the capability of adjusting the system
optimumly between nuisance disengage and failsafe operation limits
to achieve effective operation.
If electric pick-offs (LDVT1s) are to be used on the servos regard-
less of whether hydraulic or electronic voting is used, then the
electronic voting will weight considerably lessa If mechanical
feedback is used, tblre mill still be a slight weight advantage
with electronic servo voting.
The electronic (solid state) voting is subject to random failures
as is the hydro-mechanical voting. However, the hydre-mechanical
voting is also subject to sear which will require much more main-
tenance to keep the system in a ready status:.
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1110 CONCLUSIONS DRAWN FROM GROSS CONSIDERATIONS
o A triple redundant electronic system should be employed withcut
mechanical back-up.
o If a mechanit cal back-up were to be used, series servos located
as far aft as possible are preferable to parallel servos located
near the cockpit.
o Electronic Servo voting is probably more advantageous than hydro-
mechanical voting, but final selection need be made for a specific
servo/surface actuator combination.
IV. SERVO/SURFACE ACTUATOR CONFIGURATIONS CONSIDERED IN DETAIL STUDY
A. Present System
Figure 1 shows a simplified block diagram of the present system.
This system has a manual back-up system. Three multiple input
parallel servos are located close to the cockpit and provide for
all SAS and Autopilot inputs.
B. System nit"
System A shown in the block diagram form in Figure 2 uses one multi?
pie input valve dual ram servo in each of the three major axes.
The center stick, cockpit linkage extender, trim actuators and the
bulk of the control system linkages would be deleted* The servos
would be located in the aft portion of the vehicle. The mixer
and the gear shifter (elevon/elevator and pitch gimble) would be
retained. Trim would be accomplished in the triple electronics.
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C. System BI
System p is shown in the block diagram of Fiturp 3. Systen 'B
uses one multiple input valve directly on each of the seven
snrfece actuators. The center stick, sticks cockpit linkage ektender,,
trim actuators, mixer, gear shifter and all of. the mechanical.
control .system linkages um:0.d be removed. Mixings shifting, .
and trim would be accotplished in the triple redundant electronics.
D. System: C
System C, is sheen in the block diagram:of. Figure 1a System .0 is
configured as follows:
10 One Multiple input servo drives both rudder surface actuators.
2. One multiple input Servo drives each elevon actuator..
3. One maniple input' iiei;VO:drives both elevator actuators.
4. One multiple input servo drives the gimbled engine nozzle. .
The center stick, cockpit linkage extender, trim actuator, mixer,
gear shifter and 'nearly: all of the control lirkages are removed.'
Only: the short lirkages between servo and its associated actuators
remain. All mixing, shifting, and trim would be accomplished in.
the triple redundant electronics.
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V. .EVALUATION. OF SYSTEM WEIGHT AND RELIABILITY
.The Table below presents a tabulationpf the system relative weights
'and reliability for the four system configurations being considered.
TABLE I
Present
System
Proposed Systems
A.
B
G
Weight ?
343 hi
284 #
127#
163#
,
?FrebabilitrefSaccese for a
one hour Miherien:J:
0.999962
0029968
0.999966
0099961
Mean TimeBetheehlitInre
26,196 hrs.
.. .
;34188 hrs.
29,766 hrs.
25/345 hrt:.:
It is to be noted that all of the proposed systems weigh less than the
present system (from 150 to 250 pounds less) and are at least comparable
in reliability..
Table II gives a detail breakdown of the weight estimates used at arriving
at these system weights. Conservative figures have been used so that
even more weight savings are likelY.
Figures 5 through 8 inclusive show the reliability models for each of
the systems under Consideration.
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TABLE it
PEI-Aro/E. WEIGH+. CoMPARe0t4
Unit- PEscs, flot3
Pea Lhor;
Wei sHr
Fseseor Q(4160Atto0
CcilgisuRA-w.)
A
CoNficagAm- N 6
ecaNsotartok) C-
An' Used
Llksht
1/2 lin
?
. iZ lb
4.7 I6s
?
7 lb:
15 /6;
90 ibs
_
114 lbs
rns. weics,
Ara'4 Uscci
3
N/A
No Llsed
Ncj: Used
ISO f4
Not Owl
Mot Cktd
I
N/A
15
ht. applicable
Ultht
iie. lbs
?
?
?
2E lbs.
?
?
80 lbs
?
go Iiis
Am.+ ilscii
Nirk
7
Not tiso,1
Nat bisid
'no (-1-
ILIstUseeel
Mai- th.c.d
Not Wed
Z
NA Ustd
Fe all
WeJah-E
70 lb:
P
5Z.1bs
?
?
?
5 lb;
confitiv.ralci
Ariiii- usa
5
Not OA
Pot ilse.d
300 cf?
Not. (-hal
No+ Use.4
Not Uocol
I
ci.
0
70 J.
? .
,
31 lbs,
?
?
?511.0
.a. lb s
54 lbs.
vi s
L Nuif.plc. "E.t.a. SCYlit
2. Witat, it.. L ,LI- Value.
P ?1' ?
. Trini C Feel :I.:.ii y...1
, 0.)
fisLiiPhica.1 Cabie KuL)
5. 6 le.td,c. I C.61e kuYi Ca
G. ethic, Stie.. k...
I:intr./3c Exftuday
s. /14;
(3) '
. SAS Pad. 1-irw1.;
it. Liikci3 es ell
It. Other
14 IL: .
10 lbs
14 16t
3k, it,i 4
ibb lhici-
7 11:te
? 5 I6s
BO lbs
?le ildund-
t, Ilssluritk?
3
/A
3
150 4
Not ihccl
I
3
i
N/A
VI
Sa
( 3.) Ted,. nts Ito 110N Cr t: at. overneJ cu sr
(t I r ClAid i C. ovi (-kart evtr &SCA 01Par cable yun lenatit
(3) Inch. At ekdr,cal +rim eledr1 co.) .rilter
41:etti',A,' Ve MAC nn,,'ujv rhan,LAnrt
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TorhLs
I 367 163
table. run lebultb
?
234 lbs
In
a,. ukre9iLvece
-1-nrh.titJ&ndnit
(MO,
SA S
kes )
Mantle
Irinrfr
Servo
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and
Approved
For Release
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Limeaury
N0 DEL
-
PkESE/JT
SYSTEM
(c)
A= .025
A- .422.
A: .701
? 006
1
- ? Co z
At ?OC
1
A 005
012.
A o.g
A. 0.05-
MO.,
Tr; m e,.
codern
Lint o/c
Quadra...is
41 Cables
Laelkei4r5
511;qAvy 1...Astre
Elerons Elevators
Nor cit
A414 .7stma I
Lin env tb
E fern Ivry
s4,6?,c Actuators
too Elcsot.
? Two Elevons
One !Jacek_
Cenitr Slick.
( kcact,ci.$)
Eacndabic
Liitts3c.
Rp .9999834,C
Triple Rehrriont
SAS
(Roll 13i
muktielt_
-rarni-
ce-t1)U
X= .o)..5
N- .4zz.
A = .10
N - .cot
A z .005
A 2 a. a
Lin Ito c es
044r, s (;)
Ttim
in Kays
Qua Twit
SLAM,/
4n}:OrSr?
&ult.:4 Ad
!iniervi CaLl cs Elr.von
4
Too Elev s
Cen ter Si it k
(R.1k Fcti,y_hoht)
Eritnci a islc
vett.
RR = .99993927
Triple Rolosrisat
Sin
(Yaw Acts

Nu 14, p le
lorti
"?????
N- .4 a
At .025
h .00b
A ? .00z
Quest e st1
Cable 5
.01
A = 0 .1-
1
kr = x RR. x =. 999 96 /82
A -.701i
Into, C
Fed &At rr
s
0.1
Ar0.I
Ski frtl.C:: Adti fin, () Itrrsic 0 NR reitSsear4) Z4/9/ Airs
Two reciddet:
or
.1
rd y
Ptctals
Erl tv4rible
L.ittr.o)r?
- .7199 R880
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Rai/lean* MODEL - f.r'Osettit Catirt6LIRtAitor..) A
Attli
'Iplc.??/1.4.f
SAS
(REck Art0
i:icct-4.
Ron
Nu
Llpu!
'/991
S5/
Ejf 1. ntt; E.E...,..i...,
4 AJoctic
Lit.Lotic
Eeo
to
rt
Sti.i (Or. t; AC1v,iCt"-
14JoFJtiolnr
Ct fkt ?trio_
?
1
1
A - .42.? I--
1
A-
C.?.
.011
1
>i .C,71,,
A
A .005
cr TG
a
Lk.
O. I i
ft .
?
k.tv
?nett CE4tuittek
CRoll
Eitzh?_ C.
Rt..
I- tri Set ?
Tk.?
? ?i? k ' Lic-,-61( W. It
311r)
A
?iu I e
I- Se Ai)
z 997? 9/47
I
A 0C41-
LJ R4.4:0
iVy
9(?(.el7?5" ?
7 0
StA )
7.0 kle 'IA!
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11? r = 9? 974 714V-
1 MTBF, 0 lig. Atssid?.)) :--. 31, /86 824
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f-icutze
RELiriew Fr - CoriFizso EA rico
A- .C27
= 0.6
A- .11t3
Tupte Kd
4 di, fie
Su...(oLe
uovio.., (5)
SAS
Co.ite. Values (5)
Two .c?ie..e.ni
(11,14. Rtkrl rt00
Two &Intl?,
Cmc. kzIt
Two
Cut iJetr
= - 9tg,8//2. p.
A' .DZ7
A- c.
A ,ZZa.
7r ?ie_ Re kai
sr
4.4 LAI& LH-
A31,1-10,
SAS Co6le. Rn
\leave.: 04
)co Dew's,
(Ron
Two Eicon
,gyvvivn
Pr - 8p Rit Ry ? fil,4690
._.. ._ .
(1 Pie /-1, r.3,,,3 j z cp7, 744 Ahf.s
= .02.1
A- .07611
t.ti(1.4 1
I A z 0.4
ihlrEF
-
?
rt:teei,.. co. I t'l
I rileie. liet4
&Ai
(OCC- Ilej1/4,4:11,:r (2)
SAS
Cable. Wo.,
\is Eve.: CI-)
Two ZudAe ,
(Yew ;,)
Two RAI,. r
Ry - .5997?105Z
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-
A- .i123
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Reuneit.m, MODEL - RoLoLet) C
tpk ReAurdoe4 Eledricni
3 SAS
(Rht, a,,,) Co,Lie
Ru
A- 1,27
Molly& leri
Strt./03 (4)
One. Ele.volor
Ttlio elevme,
Chle. OOLC,IC
N 2.012
F',
Sw fact A (to it, )
Two Ekkahn
Euc Oct+ oil
enc. Ootz.le_
Pp - tit/31718
Title 0e4 u.s.,1 cis"
SAs
(Pon Abs)
Elect), cut Moi pktp
Calk 3ervoc (2)
Zhri TWO EleVOM
Liao ? ts.
0.2
Lfat, Acivaiin (&)
too Glev 0?1
,9999605Y
N -.0741
gt? .9499(id
/I-17er (x R. ) = ?QS: 2,75- //p.;.
C.
Ty /eh/ Rerttewl Citi
E ecincnt
Multiple DIA-
>-
SAS
Cale.
&Artio (a)
Clow At 1)
Run
To Ruckky
Ry - .999? 9 I 45-
1 54.4.5e5
(z)
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V.- (cont'd)
The failure rates used in deriving these models have been gathered
from WAD!), NAVY, and Honeywell sources.
VI. WEIGHTED VALUE TRADE-OFFS OF THE SYSTEMS BEING CONSIDERED .
Based on ths foregoing information presented, the following system
trade-off table was prepared.
TABLE III
System Trade-Off Results
Performance -
15
5
10
15
12
Failsafety
20
12
16
19
18
Reliability
30
21
25
24
19
Maintainability
5
4
5
3
2
Cost
10
7.4
7.9 :
7.5
7.3
Weight
20
' 10
14 .
17
16
Total
59.5
7799
85.5
740
It is to be noted that all of the proposed systems are better. than
the present system-ia total, and indeed in almost every sub-category
being rated.
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1 VII. CONCLUSIONS ? ?
The conclusions of this detail study are as follows:
No mechanical back-up system should be employed.
. Full authority, series-command, multiple input, redundant
? servos or valves should be employed and located as far aft
as possible consonant with other considerations.
. Selection of System A, B, or C.shouldbe made after refine-
meht of weight and cost figures by the airframe supplier.
o Type of servo voting to be employed should be made after detail
discussions by the airframe supplier and the flight control
supplier.
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