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NASA Contractor Report 1723_t'
. NASA-CR-17236619850005492
!
An In-Flight Investigation of aTwin Fuselage Configuration inApproach and Landing
Norman C. Weingarten
ARVIN/CALSPAN Advanced Technology CenterBuffalo, N.Y, 14225
Purchase Order L-61966BAugust 1984
NASANationalAeronauticsand L[_L___.. _f _"SpaceAdministration
LangleyResearchCenter ,.. -., , ,,n_n/,lad-t
Hampton,Virginia23665 -'4_GL_q,_SE,_,_CHCEr,j_-_LIBRARy,NASA
'_"_'_P-[OL'tz.VIRGINIA
3 1176 00518 4727
ERRATA \
NASA Contractor Report 172366
AN IN-FLIGHT INVESTIGATION OF A TWIN FUSELAGE
CONFIGURATION IN APPROACH AND LANDING
Norman C. WeingartenARVIN/CALSPAN Advanced Technology Center
August 1984
NASA Contractor Report 172337 was erroneously printed on the cover and ReportDocumentation Page of this document.
The correct report number is NASA Contractor Report 172366. The report numbershould be changed on the cover and in Block 1 of the Report DocumentationPage.
Issued 12-14-84
FOREWORDo
This report was prepareO for the National Aeronautics and Space
A_ministration, Langley Research Center, Hampton, Virginia by Arvin/CaZspan
_ovanceO Technology Center, Buffalo, New York. It covers the preparation,
conduct, ana analysis of an in-flight simulation program investigating the
flying qualities of a Twin-Fuselage aircraft design. The aircraft used was
the USAF/AFWALTotal In-Flight Simulator [TIFS] which is operated by Calspanunder Air Force Contract No. F33615-79-C-3618and F33615-83-C-3603. The
programwas sponsoredby NASA and aaministeredby USAF/AFWAL.
Hr. William Granthamwas the Project Manager for NASA/LRC and Capt.
MichaelMaroneywas the ProgramManager for AFWAL.
The work reported here was performed by the Flight Research
Oepartmentof Calspan. Or. Philip Reynolds was the Program Manager for the
overall TIFS program. Mr. Robert Raaford was the Project Engineer for this
task. Mr. Norman Weingartenwas responsiblefor the analysisand reporting.
The evaluationpilots were KennethR. Yenni from NASA/LRCand Major WilliamR.
Neely, Jr. from USAF.
The authorwishes to acknowledgethe contributionsof individualswho
participatedin this program: Hr. CharlesChalk, who assistedin the experi-
ment Oeslgn; Messrs. Charles 8erthe, Michael Parrag and John Ball, safety
pilots;Messrs.Robert Gavin,Ralph SiracuseanO James Dittenhauser,computer
anO electronicsystemspreparation;Ms. Chris Turpln,reportpreparation.
k
TABLE OF CONTENTS
Section Title
I INTRODUCTION......................... I-I
2 EXPERIMENT DESIGN ...................... 2-i
2.i AIRCRAFT MODEL ..................... 2-i
2.2 CONFIGURATIONS ..................... 2-15
2.3 TEST DESCRIPTION .................... 2-20
2.3.1 Introduction................... 2-20
2.3.2 Evaluation Tasks and ProceDures ......... 2-21
2.).3 Pilot Comment Card and Rating Scale ....... 2-222 ) 4 Evaluation Pilots " 2 22eo o$oooooooooooooo --
3 EXPERIMENT MECHANIZATION 3 1ooooooooooolooeeooo
).I £_UIPM_T ........................ 3-i
3.2 SIMLLATION GEOMETRY AND TRANSFORMATION EQUATIONS .... 3-6
).3 CROSSWIND SIMULATION .................. 3-11
3.4 DATA RECORDED...................... 3-11
4 RESLLTS ........................... 4-i
4.1 INTROOUCTION ...................... 4-I
4.2 EVALUATION CHRONOLOGY.................. 4-I
4.) PILOT RATING AND COMM_WT SLMMA_Y ............ 4-6
4.4 POST-FLIGHT WRITTEN PILOT CO_ENTS ........... 4-18
4.5 DISCUSSION OF RESULTS ............ _ ..... 4-22
4.6 PuT_NTIAL CRITEJ_IAFOR LATERAL PILOT OFFSET
POSITION EFFECTS .................... 4-25
4.7 MUOEL FOLLOWING FIDELITY EFFECTS .......... . . 4-26
4.8 CONCLUSION5 AND RECOMMENDATIONS............. 4-)2
5 REFERENCES.......................... 5-I
AppenDix
A MODEL FOLLOWINGCONTROLALGORITHMS............... A-I
iii
LIST OF TABLES
Taole Title Page
1 TWIN FUSELAGE PHYSICAL CHARACTERISTICS ANO TRIM CONDITIONS . . . 2-3
2 TWIN FUSELAGE NON-DIMENSIONAL STABILITY AND CONTROL
DERiVATIVFS........................... 2-4
3 a_ONLINEAR CD(_) AND Cm[@) ................... 2-5
4 GROUND EFFECT .......................... 2-5
5 FEEL SYSTEM AND CONTROLLER CHARACTERISTICS ........... 2-ii
6 FLYING QUALITIES CHARACTERISTICS ................ 2-20
7 OIGITAL RECORDING LIST ...................... 3-12
8 NORMAL ACCELERATION PER ROLL RATE PARAMETER........... 4-25
V
LIST OF FIGURES
Figure Title
I GENERAL TWIN FUSELAGE TRANSPORT ARRANGEMENT.......... 2-2 "
2 LONGITUOINAL CONTROL SYSTEM.................. 2-6
3 ROLL CONTROL SYSTEM ...................... 2-7
4 YAW CONTRUL SYSTEM ...................... 2-9
5 AUTO THROTTLE......................... 2-I0
6 PITCH RATE ANO Nzp RESPONSE TO STEP INPUT........... 2-16
7 _ULL RATE AND Nzp RESPONSE TO STEP INPUT, SCAS-1 ....... 2-17
8 ROLL RATE AND Nzp RESPONSE TO STEP INPUT, SCAS-2 ....... 2-189 ROLL RATE AND Nz RESPONSE TO STEP INPUT, SCAS-3........ 2-19
iO PILOT COMMENT CARD ...................... 2-23
ll COOPER-HARPER HANDLING QUALITIES RATING SCALE ......... 2-24
12 PIu TENDENCY CLASSIFICATION.................. 2-25
13 USAF/CALSPAN TOTAL IN-FLIGHT SIMULATOR [TIFS)......... 3-3
14 TIFb MODEL FOLLOWING SIMULATION................ 3-4
15 TIFS EVALUATION COCKPIT.................... 3-5
16 CAPTAIN'S INSTRLMENT PANEL IN EVALUATION COCKPIT ....... 3-5
L7 PILOT RATING VERSUS PILOT POSITION, (TR : 0.6 sec) ...... 4-12
18 PILOT RATING VERSUS PILOT POSITIuN, (TR = L.2 sec) ...... 4-13
19 PILOT RATING VERSUS PILOT POSITION, (_R = 2.3 secJ ...... 4-14
20 PILOT RATING VERSUS TR, {Yp = 0 ft)............... 4-15
21 PILOT RATING VERSUS TR, _Yp = 30 ft) ............. 4-16
22 PILOT RAFIN_ VERSUS ZR, [Yp = 50 ft) ............. 4-17
23 MOOEL FOLLOWImG, FLT 750, APPROACH 4, SCAS-2, Yp = 50 FT . . . 4-27
24 MODEL FOLLOWING, FLT 750, APPROACH 7, SCAb-l, Yp = 30 FT . . . 4-28
25 MOOEL FOLLOWING, FLT 750, APPROACH 9, SCAS_I, Yp = 50 FT . . . 4-29
26 MODEL FOLLOWING WITH V ERROR AND THROTTLE SURGING, FLT750
APPROACH 9, SCAS-1, Yp = 50 FT ................ 4-31
J
vi
TABLE OF SYMBOLS
b span Subscripts
mean chord a aileron
CO, CL, Cy forcecoefficients CG centerof gravityin stabilityaxes
d refers to the denominatorC_, Cm, Cn momentcoefficients of the _/6a transfer
in body axes function
g gravitationalconstant e elevator
h altitude GE groundeffect
m mass h horizontaltail
n accelerometeroutput LG landinggear
p, q, r body axis angularrates N,m model
u, v, w body axis linearvelocities NF model following
x, y, z body axis distance MTCG model CG to TIFS CG
I momentof inertia p pilot
S wing area ph phugoid
T thrust PMCG model CG to pilot
V true airspeed PTCG TIFS CG to pilot
angle of attack r rudder
B sideslipangle SP spoileror short period
y flightpath angle T TiFS
6 controlsurfacedeflection _ refersto numeratorof the
dampingratio _/6a transferfunction
e pitch angle Other Notations
T time constant [ )" refersto an axis system withoriginat the model CG parallel
bank angle to the TIFS body axis
m natural frequency (') time rate of change of I )
vii
Sectioni
INTRODUCTION
Experiments performed in the USAF-AFWAL Total In-Flight Simulator
[TIFS),(Referencesi and 2) have shown that the lateralaccelerationand the
normal accelerationat the pilot's stationare importantto the flyingquali-
ties and ride qualities of an airplane during TerminalFlight Phase opera-
tions. In Reference l, it was shown that the lateral accelerationat the
pilot's station, experiencedduring rolling and turning maneuvers, can be
excessiveif the roll damping is very high and the pilot is locateda large
distanceabove the X stabilityaxis. In Reference2, it was shown that flight
path controlproblemscan result if the pilot is locatedbehind the center of
rotationfor elevatorcontrolinputs.
The linear accelerationsat the pilot station of a twin-fuselage
airplanewill be nonlinearfunctionsof the angularaccelerationsand angular
velocitiesas indicatedby the followingequations:
nx = + i [-Xp r__ + Yp(57.3 r)+ZpI57-_.r3+ q)]p nxcG 57.3""_ 57.3 PQ-
n +--1 [ Xp (57.3 _)_ yp 57,3 57.3yp nyCG 57.3g
n : n + i [XpC57__r3_ _)+y (5_.r3 + _)_ Zp ..q_z ]Zp zCG 57.3g p 57.}
To simplifythese equationsfor transporttype airplanesthe terms involving
the angular rates squared and products of angular rates can probably be
ignored. The equationsthen reduce to
nx : 57.3""gp nxcG
nyp nyCG 57.3-----g -
nzp n + 1 [-Xp _- Yp p]= zCG 57.3-----_ ,
1-1
in ReferenceI, it was shown that the term Zp p was an importantcontributorto lateralaccelerationwhen maneuveringwith the aileronsand in Reference2
it was shown that the term Xp q was importantto flightpath controlduring
flare and lancing. It is anticipatedthat the term Yp p may be significantto
the flyingqualitiesof twin-fuselagedesignswhere the pilot is not located
in the plane of symmetry. The terms Yp r and Xp r may be significantduring
the rudderpedal inducedyawingmaneuvers.
The National Aeronauticaland Space Administration/LangleyResearch
Center has recentlyperformedpilotedgroundsimulationstudiesof large twin-
fueslagetransportaircraftin which the pilot stationwas locatedin the nose
of one of the two fuselages. This design configurationplaces the pilot a
significantdistance left or right of the plane of symmetryas well as being
forwardof the center of gravity. A consequenceof this configurationis that
rolling maneuverscause vertical motions at the pilot station thus coupling
the piloting cues Lnormally associated with pitch control) with the roll
control activity. The cues of importanceare both visual (altitudeand rate
of changeof altitude)and kinetic(accelerationrelated).
Since visualcues availablein ground simulatorsare marginallyade-
quate to permit valid evaluationof flying qualitiesduring flare and touch-
down and the limited amplitudemotion cues of ground simulatorsare quite
inadequatefor assessmentof the effects of unusual airplanemotions,it was
proposed that in-flightevaluationsbe performed for a number of these con-
figurationsusing the TIFS in-flightsimulator.The descriptionand resultsof
the TIF5 experimentare the subjectof this report. The experimentwas basi-
cally designed to evaluate the effects of cockpit location and augmented
airplane dynamics in roll on the flying qualities for terminal area
maneuvering,approachand landing. The experimentmatrix was jointlydefined
oy Ca_span and NASA/LRC personnelto permit taking advantageof results from
the NAbA ground simulationexperimentpreviouslyperformed.
The followingsectionsdescribethe experimentdesign,mechanization,
and resultsfrom this study.
1-2
Section2
EXPERIMENTDESIGN
2.I AIRCRAFTMODEl.
The baseline twin-fuselageaircraft was a 250 passenger transport
design with the cockpitlocatedin the nose of the left fuselage(Figurel).
The important physical characteristicsare shown in Table I along with the
trim conditionsfor the simulation. The linear non-dimensionalstabilityand
controlderivativesare shown in Table 2. The only non-linearcharacteristias
were the CO and CM versus a, and ground effect which are shown in Table 3 and4.
Block diagrams of the longitudinal,roll, yaw, and autothrottle
controi systems are shown in Figures 2, 3, 4, and 5. The feel system andcontrollercharacteristicsare shown in Table 5.
2-1
nn n
lS7.00
J 34_
rs,°,. _ _. _i_.-_ / ____ ,l"q_= ! $1.75 I
12500 Tw_ Body Tr_oru4_Ort13080
4-7- 02 e€$
Figure i GE_L TWIN-FUSELAGE TRANSPORT ARRANGEMENT
2-2
Table I
TWIN FLL_ PHYSICALCHARACTERISTICS
AND TRIM CO_ITIO_
Weight = 193,000ib
Ixx = 4,003,900slug-ftz
Iyy = 5,408,550slug-ft_
Izz = 9,181,470slug-ft2
Ixz = 223,410sluf-ftz
S = 2147 ft_
= 15.074 ft
b = 157 ft
CG = 0.62
LandingGear - down
y = .0 _
h = 2000 ft
V : 132 kt
Flap = 50U
_Trim = 3.15u •
_hTrim : -6.96u
6eTrlm = 0_
Thrust = 30,620 ib
Pilot eye relativeto CG_> 0.62
XpMCG = 58.5 ft
YpMCG = -29.13 ft (variable}
ZpMCG = -3.69 ft
2-3
Table 2o
TWIN FUSELAGENON-OINENSIONAL
STABILITYANO CONTROLDERIVATIVES
CLo, I/oeg 1.1499 CyB, i/deg -.03136
CLa, i/Oeg .i144 Cyp, I/deg .00563
CL6 , I/Oeg .0149 Cyr, I/deg .01345
C e 0 C i/deg 0LLG Y6'
CLGE .092OF(h) aCy , 1/deg 06Sp
CoLa] Table 3 Cy6, 1/deg .00536r
C06 , lldeg .00005e ClB, I/deg -.00256C .01493
OLG C_ , 1/deg -.01022C -.0928F[h) POGE C_ , l/deg .00749
r
C2 , 1/deg .00148
CmL_J Table 3 6aC_ , 1/deg .00023
C , 1/deg -.0443 6Spm6e
C_ , 1/deg .00050Cm , 1/deg -.0642 6r
6hC -.0087
mLG CnB, i/Oeg .00394' -.O072F[h)UmGE
Cnp, 1/deg -.00074Cn , i/Oeg -.00552
Cm., i/deg -.1352 rCn6, i/deg .00023
Cm , 1/deg -.5848 aq Cn , 1/deg .00024
6Sp
Cn , 1/oeg -.001696r F
2-4
Table 3
NONLINEARCD(: ) ANDCm(:)
a, Beg CO(e.) Cm(e,)
-8 .12603 -.0430
-4 .13883 -.2215
0 .17553 -.3703
4 .24753 -.4405
8 .35503 -.4638
12 .46453 -.4587
Table 4
@ROUND EFFECT
hWN, FT FLLhJ and Fm(hJ FDLh)
157 0 0
130 .002 .011
110 .006 .033
90 .013 .070
80 .021 .097
70 .034 .131
60 .054 .174
50 .085 .227
40 .128 .294
30 .188 .391
20 .275 .519
I0 .435 .714
0 1.000 1.000
2-5
COLUMN-TO-ELEVATOR GEARING15 o
7 3.5 7C PILOT I+_7'_ I
WINDUP LOGIC I MANUALr 1 0
_ ELEVATOR
OH _Vpc_L _ VpCL COMMAND
SASI.C. = 0
0 degWINDUP LOGIC
r 1 QILI M
OINTI.C. =0 j. SASLLIMO'_
_ deg/sec +/_ GERRI'_-]
+ lj! Is,s,o.o
KOc 1.2 QILI M 25.0 L._ WINDUP LOGIC1
K0H 0.95 KO 3.0 _ I-_8 30 SASLLIM 25.0 RELEASE _ TRIM UPHLIM O : _ HC HORIZONTAL
I _T COMMANDKOl 4.0 PCL 25.0 RIM DOWN
K0 1.0 _ 6HTRIM
Figure2 LONGITUDINALCONTROLSYSTEM
-...i1-6 SPLcSPOILER
-,1=, GEARING SPOILER COMMANDS
15SPRc WHEEL-TO-AILERON GEARING
WINDUP LOGIC! 1
I PILIM
PINT/
I.C. =0 / SASALIM !MANUAL
i /" COMMAND,,,j
+_ +"t'+ J ZROLL-SCAS
p, deg/$ec ON
_)de9 _) _RAH 1_1_ ZRAR_..._,_=(_
+ ,,..sc.s I. I<PRAH/ .AND. ISWHEELI< DWHRAH
I I
Ocw_t_ -sL__JJ ?ZRA.,c.o _L I'wH_"I>°w""'"
Figure 3 ROLL CONTROL SYSTEM
SCAS
1 2 3
Kp .37 .40 .60C
Kp 5.0 2.0 1.0
Kpi 4.95 2.0 1.0
Ktf> 0 10.0 02
K¢TC -50
Kw 1.0L
PRAH 1.0
OWHRAH 0.3
PlUM 15.0
. SASAUM 15.0
SPOILER GEARING
6 *~WpllOT \ 60
_(0. ,6WPILOT >0.- OSPFO, [) ~ O.
WplLOT
60 ---- --1-------: ---- .-1------ -r---- ---r .0 _
: : : : I
: : : : : :50 - ~--_----l------~----.-. : L -:
: : : : : :: : : : : :: : : : : :40 ------,- ---. --.- -- L -- -,- - - ----~- - - - -,
:: ::::::"0 :::: I :
I I • I II t I I I
_______L ~-------~--.---~------ • ,
! : ! : : :I I I I I I, I I I I II I I I I II I I I I I20 L ~------- .. ------_:-- ---+-------:: : : : : :I :. I I: : : : : :
10 ------t------i------- ----~------~-·-----t: : : : : :I I I • '
I ::::• I I I
~. 30~eno
[)WplLOT >0.
5w ~o.PILOT
=(OSPFO'O. ,
owIVI0>
10 20 30 40OWPILOT, deg
50 60
Figure 3 ROLL CONTROL SYSTEM (Cont.)
PEDAL-TO-RUDDERGEARING
_ _i""-4 21" __PPILOT _ 6RC+2"
/ YAW
SAS LyAWO'__ON
p_ SASdeg OFF
SASRLIM_0 +
Kr_ I 41.15
p, deg/sec Kpy t -0.5i SASRLIM 35.0
Figure 4 YAW CONTROL SYSTEM
I.C.=0. AUTO
SAUTO
REF
KVFIL EPILAG A PLAVIAS. kt q
S+I +
AUT'----O_)
AUTO
I
o - 600, deg _ _ DTH2+
T/H =_RACK, AUTO(,HOLD, AUTO
vo ooi/KVI I 0.14 PLA THRUSTKv I 3.9
K0V I 2.5 PLApi LOT_._._j 1050# I I16.16° 58.77°
Figure 5 AUTO THROTTLE
Table 9
FEEL SYSTEM AM) CONTROLLERCHARACTERISTICS
ill
FLW4CTION UNITS COLUMN WHEEL RUDOER
8eep Rate deg/sec - 21.4 -
inertia slug-ft" 1.3 0.66 1.72
ViscousFriction ft-lbftad/see 12.3 4.4 23.6
ueaaOand deg - 1.0 -
Cable Stretch _ 0 0 0
_reakout lPos) ibfs 5.0 (Aft] 2.0 (R) 12.0 (R)
Breakout (Neg] iOfs 3.0 (Fwd) 2.0 (L) 12.0 (L)
Static Friction ft-lbf 0 0 l.I
PositionLimit (Pos) 7.0 in (Aft) 60. deg (R) 2.0 in (R)
PositionLimit LNeg) 7.0 in [Fwd) 60. deg (L) 2.0 in (L)
Spring Gradient 6.0 lbf/in 0.27 lbf/° 35.6 lbf/in
Frequencyfn Hertz ).3 O.56 1.88
DampingRatio O.23 O.96 O.58
LIMITS SERVOTIME_URFACE SYMBOL
DEFLECTION RATE CONSTANT
PITCH CONTROL
Horizontal Tail 6h +i to -15° I/3_/sec -
Elevator 6e +15u to -25u 25°/sec 0.i sec
ROLL CONTROL
Aileron 6a _+15° 15U/see O.1 sec
_poiler 63p 0 to 60° 60_/sec -
YAW CONTROL
Rudder 6r +35_ 25°/sec O.i sec
2-ii
The equationsof motion programedinto the TIFS digitalcomputerwere
(subscriptM refersto a model parameter)
Force Equationstin degrees_
1. VM = -_S (CD cos BM - Cy sin BM) - g sin YMm
+TcosaM cosBM
where: sin YM = cos BM (cos aM sin e - sin aM cos e cos @)
- sin BM cos e sin
-57.3 QS CL 57.3 g (coseM cos _M cos aM + sin eM sin aM)2. _ = m VM cos BM + VM cos BM
+ qM - tan BM LpM cos aM + rM sin aM)
57.3
- T sin aM m VM cos BM
57.3_S (Cycos.BM + CO sinBM)3. BM - m VM
+ 57.3 g [coseM cos 8M sin _M- sin 8M(COSeM cos _M sin aM - sin eM cos aM)]VM
+ PM sin aM - rM.cos aM
57.3
- T cos aM sin BM m VM
Note: T - thrust,assumedto act along x-bodyaxis throughCG
1 .Vz- dynamicpressure,_ p
2-12
momentEquations (body axis)
4. qM 57.3 _S_- I CmYY
+ Izz-Ixx pMr____MM+ __Ixz r_ - p_
lyy 57.3 lyy 57.3
5. PM = (57.3_qSbixx C_
,-, I.pM-qM)+ yy zz qMrM + Ixz rM + 57._"Ixx 57.3 Ixx
6. rM 1_57.31qSb= I Cnzz
+ xx yy qMPM + xz l_M +IZZ 57.----_IZZ .57.3/
wondimensionalaerodynamiccoefficientsweredefinedby the followingequations:
a. CO = Co(_) + Co8 6ele
+CDLG(LG)+ COGE Fo(h)
b. CL = CLo + CL _ +_--_(CL&&+ CLqq)
+ CL 6e6e
(LG)+ FL(h)+ CLLG CLGE
2-13
E (Cm.e.+ Cmqq)c. Cm = Cm(a) + "_ oL
+ Cm 6e + Cm6H6H+ (LG)+ CmGEFm(h)6e CmLG
b
O. Cn = CnBB + Cn 6r +_-_ (Cnpp + Cnrr)6r
+ Cn 6a + Cn6sp6SP6a
b (CZp rr) BIB 6a + CJ_6Sp6Spe. c_ = _ p+c/ +c_ +C_6_+ C_ 6r
6r
f. Cy = CyBB+ Cy 6a + Cy 6Sp + Cy 6r6a 6Sp 6r
b + Cyrr)+_-_ (Cypp
2-14
2.2 CONFIGURATION5o
Variationsin the accelerationenvironmentand flyingqualitiesfrom
the baseline aircraftwere obtained by changesin the locationof the pilot
postionoff of the centerlineand changesin the effectiveroll mode constant.
Three pilot positionswere chosen: yp = 0 ft, 30 ft (actuallythe baseline
was 29.13 ftJ, and 50 ft. The off-centerlinepilot positionswere to the left
of centerline. The variationsin roll mode time constant were obtained by
changing the Kpc, Kp, and Kpi gains in the lateral controlsystem, they areioentifieOon Figure 3. The effectiveroll mode time constantswere measured
from the roll rate responseto a step input by takingthe time to reach 63_ of
steady state. The measuredroll mode time constantsare:
SCA5 - 1 _R = .6 sec
5CAS - 2 TR = 1.2 sec
SCAS - 3 TR = 2.3 sec
Time historiesof step inputs into the pitch axis (same for all con-
figurationsJand roll axis for each configurationare shown in Figures6, 7,
8, and 9. Only pitch rate, roll rate, and normal accelerationat the pilot
positionare shown. The effectiveroll mode time constantsare noted for each
configuration. Note the level of normal accelerationachieved with the
variouspilot positionsand roll mode time constants.
2-15
0.24
jl
0.20 ....."....... _...............
o i :
"_ 0.16 "! ............... '................................-_O" : :
k-<
== o1_ i ......i.......T..............].............i.......i............................i iF-E
0.08 .--........;-......"........_.............._........i......._..............i.......,.. i
..._ ....... 1....... _....... L.............. : .... : ', - ', .
o. ....._......._..............i..............i..................................................i.......!......i..............................................
0
0.12
oo il0.08
= iiiiiiiiiiiiiiiiiiiii!iiii!iiiiii!i!<= 0.06 ......i......_......_......_.......i...............:............_.......:.......i.......i
0.04 ...... _'...... "_............................. + .............. ';...................... -;-.......!
i : :...... ,...................................... _....... •....... _..................... ._........
0.02 ..... "...... ! ....... ;...... +...... i ...... _...... :....... .;...... _....... :...... _-...... -:
.............._..............+......•.......,_......_.......:......._......:......_......i i i ; _ = :: , ; : :
o , t I i i ; I i I , t0 1 2 3 4 5 6
TIME - seconds
Figure 6 PITCH RATE AND Nzp RESPONSE TO STEP INPUT
2-16
. 0.10 ......................................................................... i ..............
......i.......i..............T.......t......!.............._.............._...............0.08 ..... "_....... ".'....... _...... ".'....... "...... _....... :.......:.............. -i-...... !........
u .......i-...... .'--_ : ,,'i ......._".............. i ...... _....... ,
_'_ . _ i ! _ _ _ . _" __0.06_'----_............ "...... _....... :....... _"...... "....... _...... _....... "...... _........D.
_ ....i '_......].......i......!.......i.......i.......!...= 0.04 R = 6se .... i ! ..... i ...... !....... i....... ; ...... i.,I
° I li!i!ii scAlii......,_. ...... ' ...... i-...... .:....... ._...... ._....... I....... '........ _....... _-...... _....... _..... .
0.02 -- •....... i-...... _....... ._...... _-...... i .......i....... "....... ._...... "....... i...... .:
0 J]iiiiiiilJiiiiiiiiiiiiiiiiiiiiiiiill i i ! i ii_....... :...... '_....... "....... " ...... :....... :"...... _....... "...... _....... "......
0.12 "":......_ ....................................................................
0.10 ..................... -:........
50 ft
o ..............................!......!..............."_............................................. _...... i .......
_" 0.06 : :+................................... ]....... !<I : ,,
....... 4-............. _ .................................... ._....... ;
i i :0.04 : '-.................................... -_..... !
: ii : !
= 29.13 : i0.02 .......+...... !............ _"...... "
i =0 : :! i
...... +....... ;_...... ,;I= i io
0 1 2 3 4 5 6
TIME, seconds
Figure 7 ROLL RATE AND Nzp RESPONSE TO STEP INPUT, SCAS-1
.°
2-17
0.10 .................................... _............... _..................... .,,..............., I
....... ;....... ....... .,'....... :...... .,....... _......
o.o8.....,.............................._......i.......i......-_.......i......_......i.......,U
....... ,,...................... ._....... . ;. : . : ,"0 ', , , , "..... ; ....... , ...... • ....... ,,-...............= , : ....in. ', , , , : , ; : , : , ,
O. 0.06 ...... :...... '=....... _.... "_....... "....... _"...... ';....... :...... "....... ' ...... -_.......i<: ....... r...... i ..... •...... i ....... !....... ,"...... ",'....... ,;...... 4....... _....... !....... .CC
-_ i i .......i L i i ;,.-= 0.04 ........ ..........................
=o :: ,:....... : ..... L...... _....... '....... ._....... :.... : ', ;.
0.02 .... '..... L , ; , . ; , . :
o t!iiiiiiiiiiiiiiiiiiiiiiiiiiii-!iiiiiiiiilli'.'.......i ......+......,:.......,_......i.......,:......i .......i......_! i:......
0.12 ..........................................................................................
....... _...... °....... P...... •....... * .............. • ....... :....... ; ....... =,...... "....... ,
OlO......!..............[.......................................................................... ,,............... L..................................... ,,............... _-...... ;........
0.08
-- iul l ....... ; ...... l ....... ; .............. ; ....................... _ ...... _....... 'O" : i : :
_?-0.06 _......._......+.......:......._..............;.;.............
=5oft i i _ !0.04 ...... +...... .;......+'...... _....... ,;...... 4....... ;...... 4-.....
0.02i :
: :
0
0 1 2 3 4 5 6TIME. seconds
Figure 8 ROLL RATE AND Nzp RESPONSE TO STEP INPUT. SCAS-2
2-18
: : 0
0.10 ..... ;.............. "....... :=.......
o 0.08 ..... _ . ...... :.......................
qO i : :....... ; --.---; ........
......i _ ,R'2:3sec...................._........
0.06 63%SS :I-<
" .....;.............i......*.............._......_.......i............i......._......iooo, -"iiii/:i......._" " ! S'CAS-3 :: :..... •.'..... _...... ;....... ,_...... -_....... ".......i....... .=....... i ...... "....... i ......
0.02 .... ,....... ;"...... "....... ,:"...... .i....... i....... i....... i ....... _....... _....... :;...... i
.......i.......i......i.......i......i.......i......i.......!......io i i i i _ i i i i i ! i
0.12 .................................................................................• _............... _....o.. ..................... . .......
i0.10 ................................................................................. "........
0.08 ...... ,_...... :................................................................... _.......
€_ .............. ":...................... * ...... '....... " ..................... • ...... ";.......
:=_ooo_i ....... i __,a. ...,,....... :"..................... 4....... :...................... :...... ...... .i'yp= 5Oft i : i i :: jf,_
...... i.......;-......•......-;-......"..............-_......._......._- •
0.04 -_...... +...... _....... ,_....
I.....r_'i__7i ......i0.02!__ .....i............. . ......_...... -i-...... "...... -i-...... _-_--- .... _ ......
! : i i : : ' i I i : i: ' , ' l , I , l , : lo _ , i i _i i i i
0 1 2 3 4 5 6TIME, seconds
Figure 9 ROLL RATE AND Nz RESPONSE TO STEP INPUT, SCAS-3
2-19
The flying qualities of the baseline aircraft were all generally
Level i. A listingof the importantflyingqualitiesparametersare shown inTable6.
Table 6
FLYING QUALITIESCHARACTERISTICS
wSp = 2.7 rad/sec
: .69nz/_ = 4.32 g/rad
Wph = .26 rad/sec
_ph = 1.2
TR = .6 sec (SCAS- I)
1.2 sec (SCAS- 2)
2.3 sec (SCA5- 3)
wd = .77 rad/sec
CO = .30
I<b/BI= .2_/_d = 1.0
_/_d : 1.0
2.} TEST DF-SCRIPTION
2.}.i Introduction
test matrix consistingof nine separate configurationsmade up of
the three pilot positions with the three roll mode time constants was
generated. Two evaluation pilots each flew most of these configurations
zn an approach anO landingtask with lateral runway offsets,crosswinds,and
natural turbulence aodeo as environmental factors to increase the pilot
workload. Pilot Comments and Cooper-Harperpilot ratings were given aftereach approach.
2-20
2.3.2 EvaluationTasks anO Procedures
The evaluationpilot was given controlof the aircrafton the down-
wind leg at 1700 to 1800 ft AGL and performeda visual turningapproachto a
1.5 to 2 mile final approach. The ILS glide slope was interceptedin the turn
and was held until flare. A constantspeed of 132 knots was held throughout
the approach until landing flare. Artificialcrosswindsof 15 knots (using
the TIFS sioeforcesurfaces to set up a 6 mismatch)and a lateraloffset of
200 ft (visuallyset up by the pilotJ were used to providesecondarytasking,
_nus preventing pre-occupationwith the pitch task and in order to force
lateralcorrectionsnear touchdown. A combinationof a right crosswindand a
left lateraloffset or left crosswindand right lateraloffset was generally
used as these combinationsrequired the largestroll maneuversand resulting
normalaccelerationsatthe pilot station. The lateraloffset was held by the
pilot to approximatelyone mile out at about 250 ft of altitude. The pilot
then corrected to the runway centerline _pilot on runway centerline,
regardlessof where he was in the model aircraft). At I00 ft the autothrottle
was disengagedin order to allow the speed to bleed off in the flare. From 50
ft on Oown the pilot attemptedto oecrab and bank the aircraftto make a wing
low steady heading sideslip landing. A "desired" touchdownarea was defined
as being 500 ft long and 20 ft wide (±lOft off centerline)starting 250 ft
past the runway/glideslope intercept. The "adequate" touchdown area was
definedas i000 ft long, 40 ft wide ano startingat the same point on the run-
way. Airspeed requirementswere: "desired" 132 ±3 kt, "adequate" 132 ±5 kt.
"OesireO" sink rate at touchdownwas defined as 0 to 3 ft/s and "adequate" as
3 to 6 ft/s.
At touchdownthe TIF5 safetypilot would take controlof the aircraft
(or at any time prior to touchdownif dictated by the situation). At this
point the evaluationpilot would give his commentsand pilot ratingson the
voice recorderand the TIFS test engineerswould set up for the next approach.
Due to maximum landing weight limitations,landings performedearly in the
flightcoulO not be completedto actual touchdowns. For these approachesthe
safety pilot would take controlat approximately5 to lO feet off the ground.
On these approachesthe pilot ratingsdealingwith the final touchdownphase
were not given as the pilot'sgain and aggressivenesswere not as high as whenactualtouchdownswere made.
2-2i
2.).) Pilot CommentCard and Rating Scale
The evaluationpilots were briefedon the generalexperimentpurposes
and flight task details. They had knowledgeof experimentvariablesof pilot
position and roll mode time constants. However, before each approach they
were only told what the lateral pilot positon was and not the SCAS con-
figuration. This was done to allow the pilots to develop and use any dif-
ferent control techniques that may be required with an offset position and
make him aware that unnaturalverticalmotionsmay occur with roll inputs.
The evaluation pilot could make comments at any time during the
approach. However, formal pilot commentsusing commentcard of Figure i0 as
guide were given at the end of each approach. Cooper-Harperpilot ratings
using the scale of Figure ll were also given for each run. One rating was
given for the approachportiononly and one ratingwas given for the overall
task includingtouchdown. For approacheswhich did not go to an actualtouch-
down only the approach rating was given. For some approacheswhich resulted
in a pilot inOuced oscillation (PIO_ a PIO rating using the PIO scale of
Figure 12 was given.
2.3.4 EvaluationPilots
Two evaluationpilotsparticipatedin this flightprogram. They were
NAb/Langley test pilots, Kenneth R. Yenni and AF Major William R. Neely
Lcurrentlyassigned to NASA/I_RCJ. Both of these pilots have had extensive
experiencein flying qualitiesinvestigationsand had participatedin a pre-
vious ground simulatorexperimentdealingwith twin-fuseiageflyingqualities.
In the remainderof this report Major Neely and Mr. Yenni are referredto as
Pilots A and B, respectively.
2-22
i. Feel
- Column,wheel forcesand displacements,harmony
- Roll and pitch sensitivity
2. Responseto inputs requiredto performtask
- Roll and pitch - initialresponse
- predictabilityof final response
- pltch/rollharmony
- specialpilot inputs - why?
- tendencyto PIO
- Linear acceleration - magnitude
- influenceon controltechnique
- differencesfor right and leftmaneuvers
- coordinationin turns
3. Airspeedcontrol - autothrottleOFF
4. Approachperformance
- ILS: glideslope,localizercaptureand tracking
- Visual: flightpath corrections
5. Flare and touchdown
- Problemswith line-upflare,decrab,touchdown,
tendencyto float
- Any unusualmotions,visualcues, etc.
- Any unusualcontroltechniquesrequired
6. Approachvs. landing
- Which more difficult
7. Effectsof turbulence/wind
8. Summary(brief)
- Good features - Problems
9. OverallCooper-HarperRating - PIO Rating
Figure I0 PILOT COMMENTCARD
2-23
HANDUNG QUALITIES RATING SCALE
AI0fJ_M, CIr _m- S_LE_cu T,I,B_ OR NRCRAFT ODIANO8 ON THE Iqt.OT PILOT •I_ O_[RATION _ _ IN _ TAII_ O1_ I_OUII_D OPlBI_TIONe RA'rWKI
High y desirable desired performance
Pilot compensation not • factor forNegligible deficiencies desired performence
• I Felr _ Some mildly Minimal pilot compensation required for•" unpleasant deficiencies desired performanceYm,_
Minor but annoying Desired performance requirel moderste I _ I
ISit _ deficiencies pllot compensation
satlSfaCtO_f without Moderately objectionable Adequate performance requiresimprovement? deficiencies considerable pilot compensation
Very obisctionsble but Adequate PQrformence tequiree extensivetolerable deficiencies pilot compensation
Yae_
Major deficiencies maximum tolerable pilot compensation.performance Oeflclenolee Controlleblflty not in question
Major defiolencles Considerable pllOt compensation is requiredfor control
Major detiolenolel Intense pilot compensation is required toretain control
YM
it controllable? Major deficiencies Control will be lost during some portion ofrequired Operation
Pi10t de<:JsiocteOelin,tJonof_equ,rl_doperIt _onmvoh_llJdeltgnatronO/fl+gh!Dflm and/or
CooOcw*HsrperRef.NASATNO'$t53 lubDham w,thaccomDmlymgconddlo_.
LEVEL i PR < 3.5
LEVEL 2 3.5 < PR _;6.5
LEVEL 3 6.5 < PR S 9
Figure II COOPER-HARPERHANDLINGQUALILTIE5RATING SCALE
2-24
No2
Undesirable YesMotionsTend to .>
Yes 3I No
]
NO 4
Yes
Yes 5
Pilot InitiatedAbrupt Maneuvers
orTight Control
Yes6
Pilot Attemptsto Enter Control
Loop
Figure 12 PIO TENDENCYCLASSIFICATION
2-25
Section3o
EXPERIMENTMECHANIZATION
3•I EQUIPMENT
The USAF/AFWALTotal In-FlightSimulator (TIFS)was used as the test
vehiclein this experiment. TIFS is a highlymodifiedC-131 (Convair580) con-
figuredas a six-degree-of-freedomsimulator(Figure 13). It has a separate
evaluationcockpitforwardand below the normalC-131 cockpit. When flown from
the evaluationcockpitin the simulationor fly-by-wiremode, the pilot control
commandsare fed as inputs to the model computerwhich calculatesthe aircraft
response to be reproduced. These responses,along with TIFS motion sensor
signals, are used to generate feedforwardand response error signals, which
drive the six controllerson the TIFS (Figure14). The model-followingsystem
gains are documentedin AppendixA. The resultis a high fidelityreproduction
of the motion and visual cues at the pilot positionof the model aircraft. A
detaileddescriptionof the TIFS can be found in Reference3.
This experimentmade use of the followingmajor features inherent in
the TIFS aircraft:
I. Independentcontrolof all six forcesand momentsby use
of elevator, aileron, rudder, throttle, direct lift
flaps and side force surfaces.
2. Longitudinal and lateral/directioanlmodel-following
systems to provide the evaluationpilot with motion and
visual cues representativeof the simulatedaircaft.
3. Separate evaluation cockpit capable of accepting
appropriatepilot controlsand displays.
4. Evaluation cockpit instruments included standard IFR
instrumentdisplays featuringan ADI and an HSI as the
primary instruments,with angle of attack displayedon
an indicator on the right hand side of the HSI and
3-1
sideslipdisplayedon the indicatorabove the HSI. The
vertical and horizontal bars on the ADI displayedcom-
mand informationfor trackinglocalizerand glide slope,
respectively.
5. Oigitalmagnetictape recordingsystemto recordcontrol
inputsand appropriateaircraftresponses.
6. Two cassette tape voice recorders for recordingeval-
uationpilot comments,and T£FS crew comments.
7. The capabilityto simulate artificialor cancel actual
crosswinds up to 15 kts incorporatedin the model-
followingsystem.
8. A signal light locatedabove the ADI and audio signalto
indicatetouchdownof main landinggear.
The evaluationcockpit was configuredas illustratedin Figure 15.
The controlswere standard wheel and rudders. Thrust was controlledby four
throttleleverstied togetherand total thrust was indicatedon a single gage.
Asymetricthrustcontrolwas not provided.
The evaluationpilot's instrumentpanel is shown in Figure 16. It
was a standard configurationwith flight director or raw data information
availableon the VSI.
TIFS evaluation cockpit is a dual pilot side by side arrangement.
For this investigationthe right seat was occupied by a NASA flight test
engineer. The engineerobservedall approachesand landings,assistedin con-
duct of the flight test card and recordedsummarizedevaluationpilot comments
and handlingqualitiesratingsto providetimelypost flightanalysis.
3-2
ANALOGELECTRONICSAND DIGITALFLIGHT
RECORDER [.=_=_
HYDRAULIC CONSOLE
._... jr /
F ' I ---- /" C-131 COCKPIT• . _ _)DIGITAL 3 ._ (
COMPUTER _... STATION 6.5SYSTEM _ .
DIRECT LIFT FLAP (DLF) _J.
_f
°" DLF/SFSCONTROL BOX ACCESS
TUNNE LSIMULATION COCKPIT
SENSOR BOX
SIDE FORCE SURFACES (SFS) ADAPTER SECTION
C-131 AC POWER CONSOLE
Figure 13 USAF/CALSPAN TOTAL IN-FLIGHT SIMULATOR (TIFS)
3-3
TURBULENCECRDSSWIND
I TIFS
I HODEL CONTROLLER TIFS
PILOT _ AERO & CONTROL RESPONSE FEEDFORWARD_ COt_HANDS _ RESPONSEL
COMMANDS - I MODEL '-- GAINS -- :
ERROR I
FEEDBACKGAINS
RESPONSEERROR
Figure 14 TIFS MODE]_FOLLOWINGSIMULATION
3-4
/\ •
Figure 15 TIFS EVALUATIONCOCKPIT
Figure 16 CAPTAIN'SINSTRUMENTPANEL IN EVALUATIONCOCKPIT
3-5
3.2 SIMI__ATIONC_TRY _ ll_ORMATION EQUATIONS
The TIFS motion simulation system was configured to reproducethe
model'smotion at the evaluationpilot'sposition. Since the distancebetween
the CG of the TIFS and the evaluationpilot positionis not the same as the CG
to pilot positionin the model lespeciallysince the pilot may be offset 50 ft
from the centerlineJtransformationsof model states are necessary. These
transformthe appropriatemodel states from the model center of gravityto a
point which correspondsto the TIFS CG when the pilot's eye positionscoin-
cide. We denote these transformedmodel variableswith the subscrlptMF to
signify that these are the motion variableswhich drive the model followinq
system.
The oistancesof interestare (in feet):
Twin-Fuselage- CG to Pilot:
XpMCG = 58.5
YPMCG = O, -29.13,-50.1forthe three positionsevaluated)
Z MCG= -3.69Yp • -YPMCG
TIFS - CG to Pilot:
XpTCG = 33.8
YPTCG = 0
ZPTCG = -1.5
In addition to the linear transformationthere is an angulartrans-
formationthat is necessaryto take into account the pitch angle mismatch of
the two airplanes. This pitch attitudebias, eB, was used to allow the TIFS
Oirect lift flaps, which control the trim attitude, to operate about the
center of its allowabletravel. For this programthe eB = +l.deg (TIFS x-axis
I deg below model x-axis).See the sketch below for the relationshipbetween
the distancesand bias angle. The notation[_) signifiesan axis systemwith
originat the model CG but orientationparallelwith the TIFS axis system.
3-6
MODEL
CG XM
ZMTCG_
TIFS ZPNCG
_. _"ZPTCG-_ _ XpMCG
Pilot EyeZT
ZM
Therefore,the distancesof interestfromthemodel'sCG to theTIFSCG in the
TIFSbodyaxessystemare then:
XMTCG= XpMCGcos eB + ZPMCGsin eB - XpTCG
YMTCG = YPMCG - YPTCG
ZMTCG = ZPMCGcos eB - XpMcGsin eB - ZPTCG
XMTCG : 58.5 cos eB - 3.69 sin eB - 33.8 = 24.6
YMTCG = 0,-29.13, - 50.0 = O, -29.13, -50.
ZMTCG = -3.69 cos eB - 58.5 sin eB + 1.5 = -3.2
The following equations were then used in the model computer to
define kinematics of the model in the appropriate axes systems (all angular
units are degrees).
3-7
Model accelerationsat its CG and in model body axes system:
Tnx = [CL sin _- CD cos a) + m-_
ny = _g [Cy)
nz = - _g LCL cos a + CD sin e)
Model accelerations at pilot's station in model body axes system:
1 [_ (r_+ q_+ _ pr ]nx = nx 57.3g XpMCG\ 57.3 / YPMCG - ZPMCG(57.3 * _)P
1 [pZ + rZ_ qrny = ny + 57.3"---'-_[XpMcG(57.-_5+ r) YPMCG\ 57.3 ] ZPMCGP
nz = nz + 1 (q2 +pZ)]57.3_ [ XpMCG(57.--P-_5- q)+ YPMCG(57._ + P)- ZPMCG\ 57.5P
Mooel accelerations at its CG in TIFS body axes system:
nX = nX cos e B + nZ sin e B
ny = ny
nZ = nZ cos sB - nx sin eB
Mooel accelerations at pilot's station in TIFS body axes system:
• [_ ]= nX + 1 * (r*_+*_ * _- r*)+ * P-_-_-+ a*)nXMF 57.3--'--g XpMCG\ 57.5q )+ YPMCG 57.3 ZPMCG 57.3
= ny 1 * [p_Q_ _*) ( ) + ZPMCGnYMF 57.3g XpMCG\57.3 - YPMCG 57.3 (_- P*)
[ > )]n z = nz + l * (p'r* .* * ., , r*,+p*2MF 57.3g XpMCG\ 57.3 q + YPMCG(Q_r_ + p (- 57.3 - ZPMCG 57.5
3-8
The above three equationsand those below requiremodel states in the
TIFS Oody axes systems:
p* *= p cos eB + r sin eB = PNF V = Vq* q = ONF 6*= = 8
r* = r cos 9S - p sin eB = rMF _* = {: - eB
• * .* .*The angularaccelerationequationsfor p , q , r are the same as the above
with the dot variablessubstituted.
The followingequationstransformthe model'sV*, _ , 6 , V , _,* * "* "* 8"
at its CG to the valuesat the TIFS CG:
I V cos _ cos 8 + [ZMTCGq - YMTCG r*]VMF = cos QMF cos 8MF
* i * * * ]I V cos 8 sin _ + 5-'_.3[-XMTCGq + YMTCG p*)sln _MF = VMF cos 8MF
C_F = arcsin LFsinO_F]
1 * * * *]I V sin B + 7_,} [XMTCGr - ZMTCGp )sin 8MF - VMF
8MF = arcsin [sin 8MF]
= I V cos c,cos 8 - V cos _ sin 8 + sin c,cos 8cos _MF cos 8MF
8MF %F+ VMF cos _MF sin 8MF _ + sin aMF cos 8MF
z * .* £*)1+ 5--_.}IZMTCGq - YMTCG ]
3-9
i F-
L_V cos a cos B + sin a (V[57.3)cos B - V sin B B)_F = VMFcos aMF cos BMF
- sin o_4F [VMF (57.3]cos 8MF - VMF sin BMF BMF)
-X* " * * " *+ ( MTCG(-q] + YMTCG(PJ}]
I [V cos B A + V157.3)sin B - VMF(57.})sin BMFBMF = VMF cos BMF
• .., , .,}]+ (XMTcGLr] + ZMTCG[-p]
These equations were not manipulated further to allow direct com-
putation of "MF" quantities. Rather, since the computer cycle time was short
[12.Sms),the above relationshipswere used with past valuesof the "MF" quan-
tities appearing on the right hand side. This introducedan additionaltime
delay, but since the time was short it was judged insignificantin its effect onthe experiment.
The equation form for direct computationis includedin AppendixA forfuturereference.
The model Euler angles and flight path angle were transformed with the
following equations:
sin eMF = sin e* = sin e cos eB - cos e cos @ sin eB
sin _ cos esin _MF = sio _* =
cos eMF
sin YMF = cos BMF (cos O_F sin eMF - sin O_F cos eMF cos _MF)
-sin BMF cos eMF sin @MF
3-10
}.} CROSSWINDSIMULATION
An artificialcrosswindcan be simulatedin the TIFS by the deflec-
tion of its side force surfaceswith a programmedmismatchin sideslipbetween
the model and the TIFS. In this way, the TIFS sets up a wings level constant
sideslipwhich the model aerodynamicsand evaluationpilot do not see. To the
pilot, it appearsas if he were flyingin a crosswindwith his airplanehaving
a lateralvelocitycomponentwith respectto his heading. Ouring these simu-
lations,the existingcrosswindswere augmentedby an artificialcomponentto
bring the perceivedcrosswindup to 15 knots which is the maximumobtainable
while allowing for additional side force surface deflection for model-
followingpurposes.
3.4 DATA RECORDED
The pilot comments and ratings were considered the primary data of
the investigationand were recordedon a voice tape. The summary of these
commentsare presentedin Section4. In addition to voice tapes a 58 channel
digitalrecorderwas used to recordsignalsof interest. These included:
I. Pilot inputs
2. Controlsurfacemotions
3. Aircraftstates (Modeland TIFS)
4. Radar altituOe
5. Sink rate
A specificlist of recordedvariablesis presentedin Table 7.
3-11
Table 7
DIGITALRECORDINGLIST
Note:
I) SubscriptMTCG refersto a model parametertransferredto the TIFS CG
2) SubscriptMP refersto a model parameterat the pilot station
3) SubscriptT refersto a TIFS parameterat its CG
4) _ubscriptTP refersto a TIFS parameterat the pilot station
5] SubscriptMF refers to a model parameterused for model following
6) A A is an incrementalparameterfrom its engage value
ChannelNo. Variable
i AeMF
2 AeT
3 qMF
4 qT
5
7 _PE CdifferentialpressureinTIFS elevatoractuator)
8 AVM
9 AV
lOll VT
128NZMp
13L_NzTp
14 CTIFS elevator_e3T actuatorstrut)
16 eM
3-12
Table 7
DIGITALRECORDINGLIST (Cont'd)
ChannelNo. Variable
17 sin YMF
18NyNF
19 N
YT
20 PMF
21 PT
22 CMF
23 CT
24 rMF
25 rT
26 6 ITIFSelevatorcommand)ec
27 NzT
28 6MF
29 BT
30 a gust component
31 B gust component
32 hpress.
33 hGear_right
34 hGear_left
35 coc. Oeviation
36 G.S. 0eviation
37 NYMP
3-13
Table 7
DIGITALRECORDINGLIST (Concl'd)
ChannelNo. Variable
38NyTp
59 TouchdownPulse
40 aPa ldifferentlalpressureinTIFS aileronactuator)
41 NZMF
42 _ [TIFS sideforce]Y
45 _a [TIFS aileron)
44 _z (TIFS direct left flap)
45 _r (TIFS ruoder) ,
46 _a (TIFSaileron)
47 _e [TIFS elevator)
48 _x (TIFS throttle)
49 A_e (Modelpilot pitch input)S
50 _e LModel elevator]c
51 tModelhorizontaltail]8Hc
52 _as(Modelpilotrollinput)
55 (Modelpilot rudderpedal input)6rp
54 _RC (Modelrudder)
55 Model followingtest signal
56 PLA (Modelpower lever angle)
57 _AC [Modelaileron)
58 O_F
3-14
Section4
RESULTS
4.l INTRODUCTION
This section presents the results of the evaluation flights.
Includedis a chronologyof the evaluationsincludingthe task variablesand
pilot ratings. The evaluationsare also grouped by configurationand pre-
sented with pilot comment summarys. Plots of Pilot Rating versus con-
figurationvariablesare given. A discussionof the resultsand a potential
criteria Oeallng with lateral pilot offset position effects are presented.
The fidelityof the model followingand its effectsare also given. Finally,conclusionsare presented.
4.2 EVALUATIONC_NOLOGY
Three flightswere flown on 21 October 1983 out of NiagaraFalls Air
Force 8ase. Pilot A was the evaluationpilot on the first and third flights,
and Pilot B was the pilot on the second flight. There was no turbulence
during the first flight, but there was light turbulence for the last two
flights. The followingtable presents a listing of each approach including
configurationvariables,task variables,and pilot ratings. The SCAS number
refers to the roll SCAS which yielded the variouseffective roll mode timeconstants:
SCA___SSEffectiveTR
I .6 sec
2 1.2 sec
3 2.3 sec
The yp refers to distance that the pilot was offset to left of the centerline
of the model aircraft: O, 30 (actually29.13),or 50 feet. The directionof
the 200 ft runway offset indicateswhetherthe pilot lined up to the left (L)
or right IR] of the centerlineduring the outer approach. The directionof
the 15 kt crosswind indicatesif it came from the left (L) or right (R).
Approach type refers to either a low approachor a simulatedlandingapproxi-
mately five to ten feet off the ground (LA) or a completeapproachto a real
4-I
touchdownon the TIFS'wheels(TO_. Approachesmade early in a flight could
not be completed to a possible TIF3 wheels touchdowndue to weight limita-
tions. Two pilot ratingsare given. One is for the approachportiononly and
the other is an overallrating includingthe touchdowntask. Only approaches
that were completedto a real touchdownwere given overallratings,as ratings
given for simulated touchdowns without having to place the wheels on thegroundwere not consideredrealistic.
4-2
TWIN-FUSELAGE EVALUATION CHRONOLOGY
Flight .750 Winds: lOOU_ 6 kt Runway: NIAG-28
Evaluation Pilot: A Turbulence: None
200 ft. 15 kt App. Pilot RatinqApp. . SCA_ -yp RW Offset X-Wind Type App Overall
l 2 50 L R LA 3 -
2 2 50 R R 4 -
3 2 50 L L 5 -
4 2 50 R L Abort-Yaw osc.at de-crab
5 2 50 R L 5.5 -
6 i 30 L L 4 -
7 1 30 L R 7 -
8 I 50 L R 7 -
9 i 50 R L Abort-No PR
I0 I 50 R L 6 -
Ii 2 50 R L IT 4 -
12 2 0 None None TD 2 2
13 2 30 None None 2 2
14 2 50 R L 3 4
15 2 50 L R 3 3
16 3 50 L R 3 4
17 3 50 R L 3 4
18 1 0 R L 4 6
19 i 0 L R 4 7
20 2 0 L R 2 3
21 2 0 R L 2 3
22 3 30 R L 3 5
4-3
TWIN-FUSELAGE EVALUATION CHRONOLOGY
Flight _751 Winds: lOOU_13 kt Runway: NIAG-IO
Evaluation Pilot: B Turbulence: Light
200 ft. 15 kt App. Pilot RatingApp. . 5CAS -yp HW Offset X-Wind Type App Overall
I 2 30 L R LA 3 -I
2 2 30 R L I 3 -
3 l 30 R L 6 -
4 i 30 L R Abort- feelsystem jitter
5 l 30 L R 5 -
6 1 50 L R 7 -
7 I 5O R L 6 -
8 2 50 R L 4 -
9 2 50 L R Abort- systemdump in turb.
i0 2 50 L R 4 -
ll 2 0 L R 3 -
12 2 0 R L 3 -
13 3 0 R L 3 -
14 3 30 R L TD 4 5
15 3 0 R L 3 3
16 2 50 L R 4 4
17 2 50 R L 4 4I
18 i 50 R L _ 3 5T
19 i 50 L R LA_ 5 -
20 1 50 L R TD 5 6
21 3 50 L R TD 3 5
LA to 60 ft - aircraft on runway
4-4
TWIN-FUSELAGE EVALUATION C_RONOLOGY
Flight .752 Winds: 50u to lOOU_ 12 to 17 kt Runway: NIAG-IO
. Evaluation Pilot: A Turbulence: Light
200 ft. 15 kt App. Pilot RatingApp. _ SCAS -yp RW Offset X-Wind Type App Overallr
1 3 50 L None LA 4 -
2 i 50 R L 3 -
3 2 50 R L 3 -
4 2 50 R L 3
5 2 0 R L 2 -
6 3 0 L R 2.5 -
7 I 0 R L 4 -
8 I 30 R L TO 3 6
9 3 50 L R 2 3
I0 2 50 L R 3 3
Ii 2 30 L R 3 3
12 2 30 L R 2 3
13 1 30 L R 2 4
14 i 30 L L 2 4
15 3 30 L R 2 3
16 3 30 L L r 2 4.5
4-5
4.} PILOT RATING AN{)COMMENT SUMMARY
The pilot ratingsand commentsummaryare presentedin the following
tables. They are groupedby configuration(SCAS and yp). Within each con-
figurationthey are listed in chronologicalorder by each pilot. Also pre-
sented after these summarysare plots of Pilot Rating versus the configuration
variables of lateral pilot position (Figures 17, 18, and 19) and SCAS
effectiveroll mode time constant (Figures20, 21, and 22). Plots are shown
separatelyfor the approachand overallratingsas there was a definitetrend
to Oown grade each configurationas the touchdownhad to be made with its
accompanyinghigherpilot gain.
4-6
Pilot Ratin__CA5 -yp Pilot App. Overall Pilot Comments
Only with TDI
- i 0 A 4 6 Don't noticeNz with inputsduring airwork.Roll/yawoscillationduringdecrab and flare
TR=._ PIOR = 4
4 7 Roll oscillationduring flare,PIOR=6,couldnot do tight task. Up and Away it is OK.
4 - Had a lateraloscillation,PIOR = 4
30 A 4 - Had an airspeedproblem,motionsnot asnoticeable(comparedto Yo = 50)
7 - Can see differencebetwee_yp = 50 and 30.3Oft is definitelyimproved. Less pitchingand Nz motion. No problemin baselegroll-out but could not land on spot. Can seeverticalmotion with roll inputs. Task be-nign until flare. Left offset and rightx-wind hardest to do.
3 6 Got into some oscillationsin pitch and rollin flare,but easy to fly up and away withlower gain.
2 4 Liked way airplanehandledup and away, butdown low it was too quick when I startedgettinginto aileronsduring X-wind correct-ion. I also am gettinginto pitch axis dueto my percievedmotion relativeto ground.Have to extractmyself from the loop.
2 4 Had a littlebobble (oscillation)in theflare. Had to get out of the loop.
B 6 - In flare,strange feelingwhen I roll. Ifelt a heave-unnatural.Almost felt llke Iwas losingcontrolone time. May have man-euveredtoo aggressively. Don't feel theheave with roll inputsup and away.
5 - Abortedlast try due to feel systemjitterwith too aggressivecontrol. This approachI had a slightPIO after I rolledout-roll/_itchcombination.When I roll right I haveto push and when I roll left I have to pull.
4-7
Pilot RatingSCAS -yp Pilot App. Overall Pilot Comments
Only with TD
i 50 A 7 - When puttingwing down in x-wind correction,I see pitch deviationsand then I make pitch
TR=._ correctionswhich are not necessary.
6 - Would not be able to touchdownon a spot.Gettinga solutionon roll, pitch,throttleis problem.
3 - A lot of roll and heave activityon approachNo problemwith alignment,but in flare wasconcernedwith cuttingthrottleso do notget into roll axis. Gave Airworka PR=2.It was relativelycrisp responsefor a largeairplane. No perceptableNz for gentlerolls.This had more preciseand predictablebank controlthan previous(SCAS-3).
B 7 - Very noticeableheave with roll inputs.RollPIO in offsetcorrection,looks like un-wanted roll inputsfrom controlsystemwhenwings are level.
6 - Second approach,littlebetter,tried makingsmallerinputsto reduceheave,but stillgot into roll oscillationdown low, hard tomake small roll corrections,responsebiggerthan what I want.
3 5 Trying to make gentlerinputs at altitudetokeep aircraftquiet. Notice thrustsurgesmore with roll inputs. No problemwith app-roach until flare. Also floatedlong inflare.
5 - Abort at 60 ft due to airplane on runway.Problemsin approachwhen correctingforgusts.
5 6 Gives impressionof lungingand plunginginbig turns. Got heave during roll correctionin flare. Don't like altitudechangeswithroll corrections.
4-8
Pilot Rating oSCA_-yp Pilot App. Uverall Pilot Comments
Only with TD
2 0 A 2 2 No comments-justvery good approach.
_R = 2 3 Definitelybetterairplanethan previous
1.2 configuration(SCAS-1with yp = 0). Longlandingdue to power controlproblem.
2 3 Only a littleproblemwith yaw in flare.
2 - Crisp and predictablein roll. Alignment,decrab,and flare all worked well. I likeit. Small pitch bobblenear TD.
B 3 - No problemwith x-windcorrection.
3 - Initialpart of approachis pleasant. Air-plane does what I want, when I want. Feltgood, but have to have x-windcorrectionright the firsttime.
i
30 A 2 2 No apparentdifferencebetween0 and 30 feetpilot offsetwith no alignmentor x-windcorrectionmade.
5 3 Not much of a task withoutx-wind.
2 3 had good solutionall the way down, did nothave to get into it laterally.
B 3 - Not a lot of workloadon sidestepand x-wind' . ,maneuver. Oon t noticethat I m offset 30feet.
3 - Nice flyingairplane. Some problemsinlearningto use throttlesproperly,solandedlong and slow.
4-9
Pilot RatingSCAS-yp Pilot App. Overall Pilot Comments
Only with TD
2 50 A 3 - For small inputs-no perceptableNz. For bigairplanetype inputs- no distracting
TR = motions. Slight bump in the seat for rapid1.2 inputs,can perceiveloss of altitudewhen I
roll out left.
4 - Correctingfrom right side a littlemoredifficult.
5 - Nose tends to wander a littleduringx-windcorrectionworkloadgoes up near end ofapproach.
5.5 - Abort one approachdue to yaw oscillationduring aecrab. This one had an altitudecontrolproblem. Could not tell if it wasdue to pilot positionor pitch controlsystem.
4 - Balloonedin flare.
3 4 Did not feel I had to work that hard ingettingit solved as some others.
3 3 Was carefulto stay out of roll axis afterx-windcorrectionand made task easier.
3 - AirworkPR = 2, falls betweenother SCAS's
(1 and 3 _ yp =-50). On approachnoticedsinkingwhen rollingto align.
3 - Note sinkingwhen aligning. Good untilflare,then pilot gain (workload)goes up.
3 3 No problem,middleof the road airplane.
B 4 - Oon't notice any PIO tendencywith thisconfiguration.
4 - NO troublegettingit to centerllne,slightdifficultyin flare.
4 4 Pitch motionswith roll inputsnot that bad.Use low pilot gain. Have to concentrateonbeing gentle.Final line-upis hardestpart.
4 4 Same as previousapproach. As long as I amaware I am in a big airplaneand deliberate-ly don't make big inputs,I don't get intotrouble.
4-10
Pilot RatinqSCAS -yp Pilot App. Overall Pilot Comments
Only with TD
3 0 A 2.5 - Wandersa littlein roll. Less predictable(thanSCAS-2)in roll. Had a little lateral
•R = oscillationin roll in alignment.2.3
B 3 - Felt like a real airplane,best of the day.Did what I wantedit to do. Performancewhat I wanted.
3 3 Felt good, noticedthat I was not offsetfromcenterlineof aircraft.
30 A 3 5 For small inputsup and away, motionsarebenign. Can definitelysee altitudechangeswith roll inputsin flare and that changesthe way I put pitch inputsin.
2 3 Not as quick as othersin roll.
2 4.5 Old not notice any pilot up and down motionduringcorrections,but had some problemswith aileronson this approach.
B 4 5 Down rated due to altitudechange and slightthrustsurge with roll inputs.Also requiresa lot of rudder.
50 A 3 4 Lost a good solutiondue to roll input atend. Oon't reallynoticeNz responsethough.
3 4 Worked a littleharderon this approach,butstill had a littlecrab angle at TD. Haveto stay off ailerons.
4 - AirworkPR=3. Laterallyis loose. Forsmall inputsrequiresmore than I would liketo get it rollingand then I have to counter
it to stop. Poor predictability,did notknow when roll would stop. Don t noticeNzat pilot station.In approachwhere I have to be in and out ofthe roll controlmore and have to be moreprecisethan up and away, the loosenessdegradesPR to 4.
2 3 Can feel cockpitcome up when I roll outrapidly. But the more you have to correctfor the x-wind the more troubleyou get intoon flare. If you have to use aileronsinthe flare it affectshow you fly.
8 3 5 Feels fine on approach. Landingis a toughmaneuver. Ndtice altitudechangeswith rollinputs.
4-11
PILOT: I
• A• B
8,: '
APPROACH ONLY ', i7 ........................................... ! .............. ip................ •............ _ .... I
i, i
' ,k6 ............_.......................:............................,.............-IMW-...."
::. ', , , , .
,_-5 -.........................................".............. ' _..............i:'............._' ....i'<(
I-@ a
4 .............................,,..............i......................o ....._......_ ..............,J ',
i i
E : ; :
3,.... ........ i ! i " !2 ..... _....... ".............. ,.............. ,........ , L ' ',...... I¢1 .................................. .,
,
I i
1 ..... ,........ I, I ! t I J , t0 10 20 30 40 50
°.............i.............i i " " 't , i
: ', ,' ,
OVERALL WITH T.D. :7 ............ 4 ...... !...................................................... ' ".............. .:'........
: i "',6 ............ -iF...... :............................... _.....-_...........................•........,,
:_ : , ,,
< 5 ............._ .;.............,- .,:..........................................,. ....... _...... -, ,. • .......r,- ,, ,
I-- : , " ',i• i
..J_ 4 -- ..... ,L....... . .............." "............................ t{t ............. ,............... ,........ -=.
, ', , , :, 4 O I
2 -,.- ,- ., ,,. ,_ ......................'...............-.......
1 ............t , t , J , I , I , t0 10 20 30 40 50
LATERAL PILOT POSITION, ft.
Figure 17 PILOT RATING VERSUS PILOT POSITION, ( _'R = 0.6 sec)
4-12
PILOT: ]
o -A.&- B
8 ml _. •
' ............,......+.......i.......................... ! iAPPROACHONLY6
z •I- 5 ..... , ............... _........ :< ........................................................... • ...... I
, o
04 ..... .,..................................................................., ............ i_,,.•_ • ....:
, O._O
_.....".....+++,............i+..........................._",.............'_.......i....°",......i i + o +
2 .... _...... i:_- ............ 4............. _............. _O ............. _ ...... _....... L...... ,v! _ o i = i
= i i i
1 ........... ! I l I I ! " I I0 10 20 30 40 50
OVERALL WITH T.D.7 ........... , ...... "...................... . ....... ,..............
o',
i
iLo
I.-. fi -- "_ '- ............................. '...............
', ,t-" " "O 4 t. _ .............. + ...........................
o i, ',°3 ........... ONp............... ............... ,............. o._o--.... .:........ :-............ • o-.... ._.
a I 0 '+ | i 'i
2 ............ o .............................. _.............i i !
i '1 ............. t ' I , I , I , ,0 10 20 30 40 50
LATERAL PILOT POSITION, ft.
Figure 18 PILOT RATING VERSUS PILOT POSITION, ( _"R = 1.2 sec)
4-13
PILOT: I
• -A• -B
8 ....................i......."......_ • ¢,
APPROACH ONLY
; l Lo
,, i
6 _ ........... _ ....... P i
zi
I--@ 4 ....._...............,......,.i ............................. A .............. I.............. • ........
t '
3 ..... -_..... -•,15,-............ ] ............................. • .............. !....... !...... _. .......@ ' ,
2 - ....,.... ' = ,: -_'e............. ,,,-...................; 4.
1 ............I _ I , I , I ! ! ,o0 10 20 30 40 50
IOVERALL WITH T.D. I
7 ...................-, ._.................... , . ..1'..........,,iJ
6 ................. *.......
t- ',<r_ 6 .............. _& ........................... • .......o i.J
R" 4 -- ...........,_ . .............._ ............................. . ........................... O,_e.....e
....... . ....... ........ o ............ , ............. _...... _ _ ..... _.,,
2 ............ -_............................................ :...... :....... :
............ i t , I , I ; t , I ,0 10 20 30 40 50
LATERAL PILOT POSITION. ft.
Figure 19 PILOT RATING VERSUS PILOT POSITION, ( _R = 2.3 sec)
4-14
&-BePILOT:.A I
• 8 - .............. : ...... _,:....... .,.,............................................_ . _................................... . _ _:
APPROACH ONLY : :i i
' -..................--!i..............._!'i..................." i"....................................................'°-''I'F '1_ i
ZI- 5 i. ., _. ...... ,._
_" 4 .... 11" " " ] ..........................I
E.3 ..... "............... 1-
.............. ii ................, , : a, : ,
I
2 ..... d....... '...... " . , lie . _. ,_. --, ................... _....... ; ...... =............................ ,.................... I., , O,O , ", , , i , .1
, o i ,
, , , , i B1 ............ i I . I , ' ! I Ii0 0,5 1.0 1.5 2.0 2.5
.............ov_..._......w,.._.......,.o._...........................................................i..............i........o _ o
7 .................... _.............. • ............................... _ .................... . ....... ; ....... L.......i =i i ,
i=
6 .................. ' ....... 'i. _ m • ...... • ...... 4 ...... _ _ L.Z , ....... ! ............. • ....... _....... i ....... . ....... L.......
I- : I : i_ -- _ L., . _ ""_, ....................... ,
_" i ! I0 °-I 4 ==- P _ I
............_..............!..............._'_i [ i [ i'! _i,.. ....... , ....... , , _ , : ,
I ' ' Io i o
1 t _ ; I , I ' 'a i == i............. I I , , t0 0.5 1.0 1.5 2,0 2.5
ROLL MODE TIME CONSTANT, tR (see)
Figure 20 PILOT RATING VERSUS _'R, (YP = 0. ft)
4-15
PILOT: I
• A• B
i ....................._...............i..............APPROACHONLY ,,
.................................i..............i...... ............6 ................................... ,k...................... :............... ,'....... . .... _ .' ,"
_z ,k'<: 5 ..... -,............... _-............. &,-..... .;.............................. -,................... .._t ............. ,.
I-
_--O4 -- .... _....... " ............._ "1...... __...... _............................. _,...................... _ .............. 1:. , : ',= i
,
; _ , , ,2 .... _...................... _..... ,0' " ' ' ' 'IF-.... -1............. _O ............. _-...... ' '_ -;-- ',/
• , , , _ _ ....... , .... I_W" ..... • ...... .._
; I ', , ' ', ',
1 ....._...... ,, _ I I I I ' I i _ I i I ;0 0.5 1.0 1.5 2.0 2.5
8............._......i.......r......!...............!...............!............................................OVERALL ITH T.D. i
i '7 ................... 2....................................... •....... ,'--...................................., __........,
' I i i=
_- : ,,< i_ 5 .................. ' ...... !........................... ,I-- ='" "_ _" " " " ........ ,"......"...............:..........O.A-.,',-.......,.
o i i •4 ..... ,,...................... ._..... -e_ ....-_..................... ', !
_,. ._ _ ....... _....... _ ....... ,,,.......
......................._.......i..............!..........i.......'......i.......,......'.....,,.......2 ............. _ ' ' ' ' : I, "_ ...... _ ....... , ...... _ ....... _....... _ ....... _ ...... J ....... ,,.. , ,
' _ ' ' i ' ' l 'I , I , , I _ , , , I _!0 0.5 1.0 1.5 2.0 2.5
ROLL MODE TIME CONSTANT, tR (see)
Figure21 PILOT RATING VERSUS _'R, (Yp. = -30 ft)
4-16
ROLL MODE TIME CONSTANT, tR (sec)
Figure 22 PILOT RATING VERSUS ZR, (Y,, = -50 ft)
4.4 POST - FLT_T WRITTENPILOT COMMENTS
The followingare post-flightwrittenpilot commentsthat coveredthe
general impression of the evaluation pilots on the conduct and results of
their flights.
Pilot A:
These notes reflectmy observationsnoted during an airbornesimula-
tlon of a twin-fuselagetransport aircraft. Three flights, approximately
5-flighthours, were used to validatethe system and fly the evaluations. The
controlled variables, exclusive of flight control system design, included
lateral pilot position from the center-of-gravity,crosswlnd velocity, and
aircraft lateral displacement relative to the runway centerline as the
aircraft approached decision height. Other important factors included the
point at which the evaluation pilot began a sidestep maneuver to align the
aircraft with the runway; the timing for auto-throttledisengagement;the
crosswind landing techniqueused; and the gain used by the pilot during thetask or subtask.
The evaluation pilot's task was to fly a rectangular pattern in
visual meteorologicalconditions(VMC) and intercepteither the ILS localizer
and glideslopeor visual final approachcourse and glldeslopeapproximately3
nautical miles from the runway threshold. Using visual referencesthe pilot
alignedthe aircraftright or left of the final approachcourse and maintained
this relative positon until approximately4-5000 feet from the beginningof
the desired touchdown zone. At this point a sidestep maneuver was
accomplishedto align the aircraft with the runway centerline,and as the
aircraftdescendedthe flare was begun to decreasethe rate of descent. Also
for those test points involving crosswindsthe lateral drift was zeroed by
applying crosswind landing controls Crudder for runway centerlinealignment
and aileroninto the wind]. Dependenton fuelon board, some test pointswere
flown to actual touchdownwhile others were flown to a simulatedtouchdown
determined by the computed cockpit height at touchdown of the modeled
aircraft. The task presenteda satisfactoryenvironmentto evaluatecockpit
motionsin the simulatedtwin-fuselageconfiguration.
4-18
For all configurationsflown, the handling qualities and cockpit
motions of the simulated aircraft were satisfactoryduring transport type
maneuveringin the approachphase prior to approachingdecisionheight. The
lateraldisplacementof the simulatedpilot position from the center of gra-
vity caused a variationin the cockpitmotion as expected,but there was no
significant increase in perceived normal accelerationfor normal control
inputs. Althoughsmall in magnitudethe apparentverticalmotion of the cock-
pit was much more obviousto the evaluationpilot,especiallyduring the por-
tion of the approachbelow decisionheight.
This was especiallynoticeablewhen making lateralcontrolinputs as
the aircraftwas alignedwith the runwayjust prior to touchdown. Becauseof
the difficultyin preciselypredictingaircraftdirectionalresponseto rudder
inputs,the pilot chose to use the "wing-low" crosswindlandingtechnique. As
the airspeedchangedand the aircraftreactionsto ground effectoccurred,the
amount of lateralcontrol required for a stable solutionchanged. The eval-
uation pilot perceived a small vertical motion at the cockpit when these
lateralcontrolinputswere made. Coincidentwith these inputs,the flare for
landing had begun, and this required elevator inputs which also caused some
vertical motion at the pilot's station. The evaluation pilot had to
distinguishbetweenresponsescausedby the two controlinputs.
Ouring the flare maneuver used to land an aircraft,the pilot uses
several feedbackparameters to accomplishthe task of landing the aircraft.
His control inputs are conditionedresponsesto these parameters and their
rate of change. So, if while flaringthe aircraftand changingangle of bank
the pilot perceivesa change in the cockpitdescentrate, he makes an elevator
input to correct back to the desired rate. This may complicatethe task,
especiallyif the angle of bank change is stoppedor reversed. It was dif-
ficult to land the aircraftin the desired touchdownzone when the test pointincludeda crosswind.
Initially,there was no plan to include accurate touchdownsin the
evaluationtask. This was added when we realized that by includingit, the
gain of the evaluation pilot was increased as he attempted to meet the
required touchdown parameters in the desired landing zone. As his gain
4-19
increasedhe was forcedto make his controlinputs in a somewhatreaction-type
mode thus highlightingthe resultsdescribedabove.
These resultsare not necessarilyapplicableto all high gain tasks.
For example,if the task had been to track an ILS to touchdownusing pitch and
bank steering bars - a task that minimizeseye contactwith the environment
outside the cockpit - the comments would probably reflect a less degrading
effect on pilot rating. Most of the pilot commentsduring this short eval-
uation appeared to indicate a definite difference between perceivedup and
away flying qualitiesand those in the later portionof an approachto touch-
down where the primary sense used by the pilot is visual. Also the ratings
seem to indicatethe pilot'sfamiliaritywith the airplanewas a factor.
To summarize, in up-and-away flight during normal passenger and
transportaircraft type maneuvering,all configurationsflown were satisfac-
tory. During the flare for landing task, however,difficultieswere encoun-
tered by the evaluationpilot in preciselycontrollingthe rate of descentto
touchdownin the desiredlandingzone.
Pilot 8:
Comments are general - for specific comments, see tapes recorded
during flight. The TIFS program was a quick look at a lot of cases where
variablesincludedpilot distancefrom centerline[30 or 50 ft), left or right
approachmisalignment,crosswinds,left and right,and valuesof 3CA5. It was
a lot of work to do in a short time. My preferencefor the evaluationwould
have been to do only lO - 12 cases per flight. There was littletime to con-
sider the previous approach for grading before starting the next one, and
there was little time to look at the airplane because the circuits were so
short. Nevertheless,the grades probably show valid trends for the casesflown.
Concerningpilot offset - in general,thirty feet was not noticeably
differentfrom being on centerline. Fifty feet was noticeablein some casesout not all.
One of the most significantaspectsof the simulationwas the cyclic
engine surging and related vertical accelerationsfrom the direct lift flap4-20
system (OLF]. This was particularlytrue in naturalturbulence,the condition
which prevailedduring the bulk of my rating cases. The cyclic engine sound
and vertical accelerationsinvited a pilot participationwhich, at times,
. became a PIO situation. There were a few times when the engine surge sounds
almost acted like a metronomeindicatingto the pilot when to push and when to
pull. I am not convincedthat this simulationfacet did not influencebeha-
vior of the aircraftand thereforeratings.
The basic controlsystem, rate commandattitude hold was excellent.
Minimal pilot in the loop was required for desired results. No task was
encounteredwhich could not be handled,however,a consciouseffort had to be
made to make deliberate calculated inputs. Rapid control inputs based on
hasty decisionswere never acceptableand could not be used.
No combinationof variablesproved too difficultto fly the airplane
around the pattern on to final (offset]and even recover from the offset and
align the airplanecenterlinewith the runwaycenterline. From that point on,
troubles began dependingon the variables,turbulence,engine surge/airplane
heave problem. The transitionto flare and landingwas the most taxing facet
of the task (especiallyif the touchdownwas to be made at a specificpoint on
the runway]. I am not sure when this was a real problem;was it a functionof
the simulated airplane, or the simulation trying to be the airplane?
Individualcomments for each run may reveal which,when comparedto the status
of the variables. At any rate, I think that trainingand practicecould over-
come many of the problems I had with some of the worst cases. (Improvetheworst ratings.]
Ride qualities did not appear to be a problem with me, but other
crewmembers had comments regarding the effects of various combinationsof
variables on ride qualities. Perhaps that is more of a factor than the
pilot'sabilityto fly the task.
Based on my meager experiencein this program,I would suggest that
with an adequatecontrolsystem properlytuned, the piloting task is no worse
flying from a 30-foot offset pilot position than flying from a centerline
position. Llf and when such an aircraftappearson the scene my guess is that
4-21
it will be an all electric machine with Cooper-Harperratings of I for all
tasks.) l'm not sure about the 50-foot offset. That one may be a little
troublesome. _owever, I suspect that the real problemswith a real airplane
will be physical limitationsdue to geometry, size, weight, etc. or ride
quality considerations. They will manifest themselves before the pilotingproblemsshow up.
4.5 DISCUSSIONOF RESULTS
A quick reviewof the pilot ratingdata and plots shows much scatter.
However,there are some significantresultswhich are apparentwhen a thorough
examinationof the ratingsand commentsare made.
o BaselineConflquration
First of all the configurationwhich can be consideredas a baseline
conventionalairplane,SCAS-2 C_R = 1.2 sec) with yp = 0 ft, was solidlyrated
a level I airplane. Pilot ratings of 2's and 3's were given during six
separate evaluation approaches, three of which went to actual touchdowns.
This indicatedthat the configurationwas a good one about which the experi-
mental variationsof pilot positionand roll mode time constantcould be made.
Any characteristicsor problemsthat were broughtout by the evaluationpilots
should be due to the experimentvariablesand not some underlyingproblemin
the baseline configuration. The only mildly unpleasant featuresdealt with
learninghow and when to use the throttlein controllingairspeedand learning
how to use the ruddersto decrab the aircraftfor landingin a crosswlnd.
9 Roll Mode Time ConstantEffect
There is a definite trend in pilot ratings versus roll mode time
constant. From the overallratingsshown in Figures20, 21, and 22 it can be
seen that the mid-value TR of 1.2 sec for SCAS-2 consistentlyreceived the
best ratings, no matter what the pilot positionwas. The fast TR of .6 sec
for SCAS-1 receivedsignificantlypoorerratingswhile the rating for the slow
TR of 2.3 sec for SCAS-3 were only slightlyworse than those for _R = 1.2 sec.
_nen the pilot was on the centerlineof the aircraftwith TR = .6 the pilot
gave ratingsof 6 and 7 for the two touchdownapproaches. Commentsindicated
4-22
that severe roll/yawoscillation(PIOR = 4 and 6) occurredwhen ever the pilot
tried to do a high gain task such as a flare and spot landing. Up and awaythe aircraftwas fine.
As the pilot positionwas moved off the centerlinewith the fast TR
of .6 sec, the normal accelerationsthat went along with roll inputs com-
pounded the roll control problem. Though this is not apparent in the pilot
ratingsfor touchdown,there is much scatterin the approachonly ratingswith
the pilot at 30 or 50 feet [see Figure 17). Ratings from 2 to 7 were given.
This wide range of pilot ratings indicates that the configurationis very
highly task dependent. If the pilot can use low gain and make gentle
maneuvers the configurationwill be rated highly. However, as the workload
goes up and quick maneuvers must be made, the ratings deterioraterapidly.
There were many commentsdealingwith the necessityof stayingout of the roll
loop to avoid PIO's. The pilots mentioned the disturbingvertical motions
associated with the pilot position as being "unnatural" and yielding a
"plungingand lunging" impressionwith large inputs. These commentsindicated
that the vertical motions were much worse at 50 feet than at 30 feet. At
times the pitch and vertical cues observed by the pilot during roll correc-
tions prompted him to make unnecessarypitch inputs. With the pitch rate
command/attitudehold control system these unnecessary pitch inputs could
easily disturb an approach that had been set up properly. The outcomecould
be a ballooningflare and a long float or a hard landing.
8oth the _R'S of .6 sec and 1.2 sec are Level 1 (see Figure ll page
2-24 for definition of Levels] according to the Military Flying Qualities
Specification,MIL-F-8785C,which states that Level i TR'S must be less than
1.4 sec while Level 2 XR'S lie between 1.4 and 3.0 sec. However, the above
results indicate that .6 seconds may be near the lower limit of satisfactory
roll mode time constantsfor large airplanes. The problemsseen with the fast
roll mode in this experiment are similar to those seen in the in-flight
investigationof fighterconfigurationsdone in Reference 4. The resultsof
that study showed that roll ratchetingand PiO's could occur in high gain
taskswhen TR was reducedto less than .25 sec due to abruptroll response. A
similar phenomenon may be happening with the present large airplane con-
figurations,thoughnot deterioratingto a rachetingproblem.
4-23
The slow roll mode time constantconfiguration,SCAS-3,TR = 2.3 sec
yielded generallyborderlineLevel 1-2 pilot ratings [see Figure 19). This
would be expectedas the MIL-F-8785Clevel 2 region for TR is between1.4 and
3.0 seconos. Pilot commentsindicateda "looseness" in roll controland that
it was less predictablethan the other configurations. The most interesting
featureof these slower roll mode configurationsis that the pilot ratingsdo
not get worse as the pilot positionis shiftedoff of the airplanecenterline.
The pilot ratings remain in the 3 to 5 region for all pilot ratingsand the
commentsare similar. The pilots did noticealtitudechangeswith roll inputs
but aid not feel they were significantenough to degrade their ratings. It
appearsthat it is the normalaccelerationrather than just verticaldisplace-
ment during rolling maneuvers which cause problems. The actual altitude
changeat a specificpilot positionis the same for each SCAS for a given roll
attitudechange. However,the normalaccelerationis proportionalto the in-
verse of the roll mode time constant,as the p and therefore,nz = (P) • lYp)Pincreasewith decreasingvalues of roll mode time constant. With slow TR, the
normal accelerationsare low enough that they do not affect the ratingseven
with the pilot offset 50 feet [see Figure 19). With the mld-value TR the
pilot ratingsbegin to degradeat the 50 foot position [see Figure 18). With
the fast roll mode constantsthe ratings degradeat the 30 foot position for
the approach ratings and are poor in the touchdowneven at the centerline
pilot location[see Figure17).
o Pilot PositionEffect
Most of the resultspresentedhere were really discussedin the pre-
vious section on the effects of roll mode time constant. The effectsof the
pilot position and roll mode are highly inter-related. For all of the SCAS
configurationsthe pilot commentsindicatethat the pilots noticedthe effect
of being 30 or 50 feet off the centerlinewith larger effectsbeing noted at
50 feet. The effectswere manifestedthroughperceivedaltitudechangeswith
roll inputs for all SCAS configurations. These effects were more apparent
near the ground than up and away. With the slow TR of 2.5 sec, though the
pilot noted the offset,it did not affect his ratingsor comments(see Figure
22). However, as the TR was decreasedto 1.2 sec and then .6 sec the pilot
4-24
offset position had significant effects on pilot ratings and comments, As was
mentioned previously, it appears as if normal acceleration during rolling
maneuvers rather than just vertical displacement is the driver of poor flying
. qualities. The pilot has to be 50 feet offset from the centerlinewith TR =
1.2 sec before pilot ratingsdegrade into the Level 2 region. With TR = .6,
the pilot ratings of near Level 3 were received at all pilot positionsforhigh gain pilot tasks.
• Learninq£ffect
The chronologicaltable of ratings in Section 4.) shows significant
improvementin ratingwith time in Pilot A's ratingsof _CAS I at 30 feet and
at 50 feet. The rest of the data show essentiallyno change with repeat runs.
Since both pilots commentedon the large number of configurationsseen in a
short time and the feelingthat they were able to perform better as they had
more experience, there was probably some learning present. However, the
ratingsdo not reflectthis, in general.
4.6 POTENTIALCRITERIAFOR LATERALPILOT OFFSETPOSITIONEFFECTS
It has been postulatedthat the normal accelerationexperiencedby
the pilot during rollingmaneuversis the characteristicthat causes problems
when the pilot is laterallyoffset from the airplanecenterline. A parameter
which may give a measure of this effect is the ratio between the maximum
incremental normal accelerationexperienced at the pilot station and the
steady state roll rate for a step roll input: Anzp/Pss. This is similarto
the lateralaccelerationparameter: Anyp/p which was developedduring an in-flightsimulationexperimentdealingwith very long supersoniccruise aircraft
configurations(Reference1]. The pilot position was far forwardand above
the aircraft'scenter of rotation for rollingmaneuversand experiencedlarge
lateralaccelerationswhich degradedthe flyingqualities.
The valuesof &nzp/Psswere calculatedfor each of the configurationsflown from the step response time historiesshown in Section 2. The results
are shown in Table 8 along with the range of pilot ratingsgiven for each con-figuration.
4-25
Table 8
NORMALACCELERATIONPER ROLL RATE PARAMETER
SCAS TR(Sec] -yp(ft) Anzo/Pss Pilot Ratings(q/de_/secI Uverallwith TD ApproachOnly
i .6 0 0 6-7 4
i .6 30 .019 4-6 2-7
i .6 50 .033 5-6 3-7
2 1.2 0 0 2-3 2-3
2 1.2 30 .011 2-3 2-3
2 1.2 50 .020 3-4 3-5.5
3 2.3 0 0 3 2.5-3
3 2.3 30 .006 3-5 2-4
3 2.3 50 .011 3-5 2-4
There is only a loose correlationbetween Anzp/Pss and Pilot Rating
due to the scatterof Oata. However,when neglectingthe yp = 0 configuration
it may be postulated that values of Anzp/Pss above .02 g/deg/secwill yieldunsatisfactoryratings while values below .01 g/deg/secwill yield satisfac-
tory ratings. It is interestingto note that the maximum values of the
lateralaccelerationparameterfrom the Reference1 study for Level 1 was .012
g/deg/secand for Level 2 was .035 g/deg/sec. Therefore,both of these sets
of data indicatethat maximum magnitude of linear accelerationthat a pilot
will tolerate during rolling maneuvers before it starts to deterioratehis
ratingsis in the neighborhoodof .O1 to .02 g/deg/sec.
4.7 MODEL FOLLOWINGFIDELITYEFFECTS
The fidelityof the model followingduring this programwas generally
gooo. Some examplesof typical runs where large roll maneuverswere made are
shown in Figures23, 24, and 25.
4-26
Figure 23 MODEL FOLLOWING, FLT 750, APPROACH 4, SCAS - 2, Yp = -50 FT
4-27
PM O-
6.25 de
PT 0
2.5 degJsec
rM 0
2.5 deg/sec
rT 0
0"3125g"]N._ !l t-I ! ! i I I I ! I i I '. I [ I ! [1 ] !l i [ ] .].l::l...l:l.I l.l..;:].] I i I:1 i 1. I: ::F::l::!: _t I i I I ! i i 1 i i I i ] I ] I ! I I ] ] I I:l I ] ! ] .11" " ' ! I..1 I . i ..... I :: I ::t..] l] :_
I t i i i i i I ! I i t i i I i ] i I I t / ] I i ! ] I l ] , :: ^ t : I I::1 I] !_/; i i I i ! i i t _, i ^i I i i I t [ [/"d I I l! _. ] _L .... I . I I I.I.",: t ..... "_ .I :' ._,1] [..:!:LJ :5
Anz I _"_1 J,".,._lt¢-'_ hi.. I^1 tA\i /_. I !..d t I J,_ _f_1 Y \1 ....1 . _ : 1_ ].I:IA'" _ I _./._ l l^. # llr:^l.,_].:t:_.F i i'_t".,i/; _ k/V!\i ,, I\:1.,'# i_l lJ!'l I\i'_. q V i \_ \ ! \ :t" JJ _- fl / _.b'_ , _l/ ti_TI T:: ;.
PM 0 ; t [" ''q _ "_- iW _ t I I 'V I I ! I \ _ V - . i IA, i 1 _ 11; I ! : :..,.I it 1!;I | i ! ', tb' ill I.. € :x i .: :r i..
, i, i, J_iil I., I ;:11I Ill,, 1_:, _, _.... , ,:
/_1 i ; I i [ ', I i I I ] ! t ] ! ! i I I,l I ll I i 11 '[ : ,1 I I i I '1: I I tlil :l
^ l! | i ! , I i , ; : _ i , 11_! ] _i i I I I I !. Illlh I I l_FJ, fll' I_llJ I | 1 } J I 6 Il t _1 I _I_ I t ItM I.I f.L J. t .i: l.tl t
p.,. --i1__%i___. y___.___._ e_{ . -.. ' : _ i "M] Ikit;_l]t_ tJ'i_kJi: il ]il _J_JL:_]__3_3 11, I_i. IlL
.J, ;,; .... ;,. ;,, _1-_,,,,, ,_'-t-H_1-h!-ttt-l_l-tl-1 t-t-l-l-,-l-t--br ,-r-r-r--r---r-1-,,, _
Figure24 MODEL FOLLOWING,FLT 750, APPROACH7, SCAS- 1, Yp = -30 FT
_-28
"-_ _ l"s_'ond
............ _ ....... • ............. : • . . ,. . , . _i[/_.... . .. , ....- .,. o _ ___ _, :_. I ..........,_,,. A ._'" .. : ............ _f _ "::'-_- ........... _-_'--- ¢_. _- "-' :_.-_.-__ / " /-' _: : "|:
7:[.:77:• :::: ..... ._/i: L: 7: ............ :_'::;i'::: ::.:::::::_:::
2.5 d_l_ ] .......... • ..........................
............ " !....................... +......, A ......-fi- , ;.-".....
qT 0- : ._." -' " "- _" ' " _-_'__' "" ; _ _- ' " _..... T"""r(:_:q 1_'"
.....................................:,_+.............................,..............._!_,_++L_-_:1:1!:i: ................_
_:-:_:_J_......:.........._,...._ :: '.......I....':_'_,................,.......'_.........._............_-__-_'T" "+ ........ +....... i .................. , _ : . ; .... ' ...................... ! .....t : ....... ; ' I ............. _--_"'-. _--_
_:::-:-_:::_:::;:_::::-:::_F!:_ i'_,.;::_,:::_;::::::::_::::::_:::-_(:_::'_:::::___--;--...--..........:....................:..7:I..: :: ........ki"_!.....I............._.................._.................._ -'-.I........._--i--.i.-_-_
6.25 deg/lec _- . ; .................... , .......
........................................................:._..............._......._:...................__-_-_, _- _ _i_ ........_'_ ...................._............ ;'_'....... _, ,PT
- : _ _:i:I...................'...... ........................_........................' ',,I
__._::__-: ............. _......... '............ ,-k ....... _........:. ;.................._.:.. ............. _ _. i_/I
• : • • ' ; I . .......................... :--..................+...........,................ ;..___1I ] I =_2.5 deg/II¢ ...... ' I ! _ ";,-!-Y-':_I-r I-l-,
Ii ......... ---_---_._ , -I .... _ ,_:_............ .... _ ........ : _I,_IIII :, :,_ _.... !I, L-_(! i'_!i i--',-';-r-r'_.II;I\Ii_llLI ]
__ ' _'-'7""""':" "" "'"_""_ " _ "'" I _" "_.......?..... . "i......L-_,.,-;--._. + '_ " , _ . i . ! i ' I
2.5 deg/s_€ ..............................
U
___,z,_,........_ ::!::::::I_...... _ _ _ v--_ ....,i,0.3125g : " : :[i ::: : : : : : : : : : : : : : : : : : : : : : ' : ...............................
::::I_-:-..-:.............:................I .......................i.......I-_.-.--p..--_-_.---_-2-..I--L.._--_--L-L--_..I--[..._..L._-L_:._L_LII ' l I ! I 'I I I I ...... ""I. :. ...._ ...........I_...................._...._.._..._.-_--.--_.--._----F-_---_-G._--k-_-...I-4..I.-_.......l-..f."-_-p.-_-._, _ I
An z . . _. , ........................................................... ri.t_......I_-_.L-.i.' .;...... ' :.._ _._-.. l ! _ t l. I
0.3125 ................ ; ....................... : ..............................
• _ . _: _ - : I: ..: _. t I.................,........ _ _ _=_ ++."". _'._._.__. I ,_,: , _ _':............_.........._: : ! .... ::_ :::::_::::::_::_::_::_:::::::::::::::::::__!::L___-__
" " _ " ! .... : ........ _.......................... ,-,"_ ..... _----4_' '-.-.--_ ..
Figure25 MODEL FOLLOWING,FLT 750, APPROACH9, SCAS- 1, Yp = -50 FT
_,-Z9
There was one characteristicof the model followingthat did affect
pilot comments. This dealt with the coupling in of the TIFS' throttlewhen
roll inputs were made. As a roll input was made with the pilot offset from
the model'scenterline,a normal accelerationand altituderate was generated
in the model. This forcedthe directlift flaps to move to match the vertical
response. An unwanted by-productof the flap deflectionswas a drag change
which produced velocityand longitudinalaccelerationerrors with respect to
the model. These errors were fed back to the TIFS' throttles. Since the
TIFS' throttlesare of relativelylow bandwidththe TIFS was not able to elim-
inate the V and V errors quickly. Sometimes a TIFS' throttle surge and
oscillationoccurred. This also happened occassionallyin turbulencewhich
producedvelocityerrors. The pilots note_ this characteristicin their com-
ments and it sometimes disturbed their control of velocity of the model.
However, the matching of the pitch, roll, yaw, vertical,and lateral axes'
responseswas good so the evaluationsof the flyingqualitiesof the aircraft
in these axes can be consideredas proper.
An exampleof the throttlesurging and oscillationwith roll inputs
can be seen in Figure 26. The large rolling maneuverscaused Iarge normal
accelerationexcursionswhich were matchedby the TIFS. These excursionsare
in phase with the VTIFS oscillationsdue to the drag caused by the direct lift
flaps. The V error then caused the TIFS' throttlesto surge and oscillateas
shown on the bottom track of the figure.
4-30
"_ _1_ 1 _nd
_. ...... . ....................... _---_:.-_-_ ........ . .1_ .__.,., ....... _ ,_._._ . ._ ,_. ,_
'*" PM Ol _i " ";/' " "_ ""," • i i . i .:"T',.:.,o{,.I,_ i i.i i _i_ ... i /i t "/_',,._ /'_ .. ,/P',I . . ._ i . " it'!, . . i : .
• _.,,../ ._ _:_;,'......." ."-,'"_,...; _,_....L,..Z_;..3__-_ •t__..• /.',.- _ "_ -,_ .I.... %w. . _ ....... _/1_ V ?- ,
......................... " ............. V ..... " -. J _," " 'J ....
": i''.kJ _.......... _ ...... : : ;-: .. ........... _'_ ' " /_ .......... '_ ....... "'_:PT n-Jk ...........i .........., .... _: . .r _-_/' ,_,, : i'J:L"_;"_ ',_ .... /'- •., ............ • _ _,,,- _ _ _ ._ _' . ./ _ ...... _......._ v _ "" _- _" " " _ =- _ _"€ _.... t".... #""_ _ "_ "/I " '' _.... ! _ '
.......... -_...,/_.. ....... _ _ , I • -_ ,- _ , _..../ .....,_ ..............,............ i .... ,k,.__,_., ........t,_,,........_.....,,_ _, ,_L/ .........? i.............................. ..........: ......._:";4 ................ _..... v .tl .. i-kl._,/t : ._. ,:. ..... _\ ; II.J.7iI ............: .................. ; .......... : :...:; ; :: .. ::_.:..; ........... t :i ............. ._i ...... ,,/-,-....11:....
o.31_so -_ ,,, I ...... '...... _ ...............IH
AnzpM 0-1 ___'!:! e', _ ,,1., :.-. .._ .... n,_..!r ....... _;,_-_,N:.,..i .......i ,'..t...... _!1_. I "/'%.: ..... ;q_ _"--f---i..l_,i............_"it---I.......... _- ' _ .........................._- _:..... _ _ b _. k........./ l ............................, , t _7......,,.,......._,......._-_.....t
0.311111g -_ ...................... _ ....................................
z 0 "-tK.... , _ ...... _-..................... _.._.........
_'_"_"_-1 . ::i, :"__"_- __ _........................,.............__ ........ :. ., ,
• _ - :--==-::::...........:"-_- • :, _"iv, !-_-_I'_.......__-"_t:.7_"_- .......:----i--_-.:----;.....................:....... ' ......................' ......;_-i-_'!_t -...................................... "-._.-......_--.. -q-i ' " ' '•-:-_-.... _--.,.-.;.............. • I .................... _................. _"'+ : ....;................ t _ ± _;.._ _ , iJ ...................... +.t-I.....
2 2 ................ ' ...... ,-i: .'_.5 ft/_ -1
l .....Z. :'.X...,:_ ........... i
20 dllg/leC "l: ........ :. i _ . , " 1 ' " " T _ _ ' ' " : ...... _ ....../_;:w_- :.: £_;7,'= ': ..... it;: _11_ 1-_I _ q........_-........... _ ,.. _ .... _ I1_........ _ ..... _.._o,: oJ_-!,i,-_, ..........,_.,_ .........._?__
..1.. , ".................................. _ ............................. :.... ! " :..::":': :-..-:i:-7::7:::i.77:.:.:2T..rTt.,l125deg/lllic--i, t ..... : I :. '. : : ' ' '
/ ..... i ...................... ' I ...................... _................ t ' ,. I ......; ;... :._; ;._.;:...:......... ; _.j..
_-,.,, 0-.I.:..I = " , .... : .............. : ......... ; _ :";.._-A_:..-,...--_ IT----"TIFS i ' "= _ ...................................... ; P 1 l • " _ = I r + P I Irl
/ " " " l ...................... ' t " i " " : I ' " ...... _ ...................... i ........ lI'_.. " i ....... i .... l _ d I _ _[
Figure26 MODEL FOLLOWINGWITH V ERRORAND THROTTLE SURGING, FLT 750,APPROACH9, SCAS- 1, Yp = 50 FT
4.8 CONCLUSIONS AND RECOMMENDATIONS
• Lateralpilot positionhas a significanteffect on pilot ratingsand
commentsduring landingapproachand touchdown.
• Factors affecting these ratings are the actual distance that the
pilot is offset from the centerlineof the aircraft,roll mode time
constant, and degree of difficultyof the landingtask (crosswinds,
turbulence,spot landing).
• For the baseline aircraft configurationand type of control system
flown in this experimenta lateralpilot offset of 30 feet generally
had little effect on pilot ratings while at 50 feet the ratings
deteriorated.
• Roll mode time constanthad a significanteffect on pilot ratingsand
commentsas the pilot moved furtheroff the centerline. With TR = .6
sec pilot commentsindicatedproblemsat an offset of 30 feet, while
with _R = 2.3 sec, there was no deteriorationof pilot ratings or
opinionseven at 50 feet off the centerline.
• Problems that the pilots had with the large pilot offsetsand fast
roll mode time constantsshowed up as coupledroll and pitch oscilla-
tions. Pilots made unnecessarypitch inputs due to normal accelera-
tions and vertical displacements observed at the offset pilot
positionduring rollingmaneuvers.
• A potentialcriteria for lateralpilot offset positioneffects deals
with the ratio of the incrementalnormal accelerationat the pilot
station to the steady state roll rate for a step input: Anzo/pss.
When the value of this parameter reaches .O1 to .02 g/deg/sec a
deteriorationof pilot ratingsand flyingqualitiescan be expected.
4-)2
• Both pilotscommentedon the large numberof configurationsseen in a
short time and the presenceof a learningcurve. Althoughthe pilot
performancemay have been influencedby learning,the trend is not
reflectedin the ratings,in general.
• At the time of these evaluations, the TIFS throttle controls
occassionallyproduced undesired inputs in response to rapid drag
changes in the model and in the TIFS itself. Evaluationpilot com-
mentaryindicatesthat there was a tendencyto chase these inputs and
produce PIO's, particularlyin rough air. This anomaly was not a
major factor in the experiment since the poor configurationswere
poor without throttlesurgingpresent and PIO tendencieswere found
that aid not involvesurging.
• Further research should be done to study various solutions to the
problemof _nzp when roilingsuch as offset roll axis and wings-level
sidestep maneuvers using side force. The runway width requirementfor aircraftof this type should also be defined.
4-33
Section 5o
REFERENCES
1. Weingarten,N. C.: "An Investigationof Low Speed Lateral AccelerationCharacteristics of Supersonic Cruise Transports Utilizing the TotalIn-Flight Simulator ITIFS)", NASA CR-159059 and Calspan Report No.6241-F-2,July 1979
2. Weingarten, N. C. and Chalk, C.R.: "In-Flight Investigationof theEffects of Pilot Location and Control System Design on Airplane FlyingQualitiesfor Approachand Landing",NASA-CR-16)II5and CalspanReport No.6645-F-7,December1981
3. Reynolds, P. A.: "Capabilities of the Total In-Flight Simulator",AFFDL-TR-72-39,July 1972
4. Monagan, S. J., Smith, R. E., and 8alley, R. E.: "Lateral FlyingQualitiesof Highly AugmentedFighter Aircraft" AFWAL-TR-81-3171,March1982
5-I
AppendixAFOLLDW_IGCONTROLALGORITHNS
The controlalgorithmsin use for the twin-fuselageinvestigationare
specifiedbelow in terms of linear gains. Some of these gains were fixed,
_ some varied inverselywith model indicatedairspeed,Vim (kts),some varied
inverselywith model true airspeed,VTm(fPs),and some variedinverselywithmodel dynamicpressure,_m(PSf).
The errorgainsmultiplythedifferencebetweenmodelmotionsat the
TIF5centerof gravityandTIFSmotions- forexample€B = flMF- 6.
These gains were as follows:
6e
Cq -2.18 132z 6r /132 1- T , sec -- = 3.03 _V_m , secVim €_
6e -5.45 132_ 6z /132 )% - v_m ,_ -1.2o_k-- , sec, -- -- = Vim
6e 1322 _l 6Z / 132 1--= -- , sec -- = _8.06[V__m , __j% -2.73 V_m €_
_a /i32\ _x% --2"80_V-_m),sec - 4.13 132__ V-F- , _/fps2
im
€_ -3.94 -- ,__ - 9.07 vT , _/fps\ i m Cv lm "
6r
= 0 Vi = 132 kts at trimer m
_r /132): , __
A-1
The feedforwardgains were as follows:
6e 59.4 6r b-- =-.43 -- , seez ;--1.0) _ , sec
qMF qm PMF "'T m
6e 6z 59.4 deg/g-- = -.23 , __ _ -67.7 -- ,°_IF nZMF
6e 6z
6zCFF _ -.08 ,-- °_IF -7.16 , __
6e c 6z-16.5 -- sec = -.84
C_F 2VT ' 6eCFF ' --m
6e c 6x
+-6.21 2-_Tm , sec -- = 8.2 , %/fps z%IF VMF
6a 59.4 6x- -.99 -- , sec z - 263. , %/--
PMF qm sinYMF
6a 6x--1.70 -- : .137 , _/psf
_MF ' -- qm
6a b 6x-).i) , sec - 1.97 _ %/deg
rMF 2-_Tm O_F 59.4 '
6a b _Y = 142.1 59.4 , deg/g
+-8.80 2-_Tm , sec nPMF YMF
-.19 = 3.049 -- 9
6rCFg BMF _
6r 59.4 6y b
rMF --.71 --qm , sec rMT :-.38 2-_Tm , sec
A-2
6r -.89 -_L :-.63BMF ,, -- 6rCFF
ar b. rNF 1.26 2V---T--, sec : .03
m 6_F F
qm = 59.4 psf at trim
VTm = 223 fps at trimc = 9.52 ft
b = 105.3 ft
CFF signifiesthe feedforwardpartof the commandsignal
The model followingvariableswere calculatedfrom the transformation
equations stated in the main body of this report. As mentioned, these
equationsdo not solve for the variablesexplicitlybut use past valueson the
right hand sides. The error introducedis a time delay of one computercycle
time. For this program, that was 12.5 ms. In other programs that use these
transformations the cycle time may be significantlylarger and this procedure
may not be acceptable. To avoid the additionaltime delay, the explicitform
of the equationsis needed. This is given below introducingthe three com-ponentsof V to simplifythe expressions.
Using u = V cos a cos B
* = V* B*v sin
* V* B* *w = cos sin
* I * * _ y,then UNF= u +_'--_.3 (ZMTcGq MTCGr*)
* 1 * * *VMF: v +_3.3 (XMTcGr - ZMTCGp*)
* i * * •WMF : w + --57.3 (-XMTcGq + YMTCG p*)
A-3
and VMF = (_F + V_F + W_F)_Z
VMF
sin 8MF - VMF
WMF
sin _MF = [_F + W_F)12
Using the differentiationof the equationsabove and the fact that
_*=_,,&*=&,and_*=_,
* * * _ * ., ,. _,)then _F = _ _ - v cos e B - w & + (ZMTcGq - YMTCGV
* ** .* *
v _ + u _ + 5--_.3(XMTcGrVMF = -T , - ZMTCG P*)V cos e
WMF * * * _ * "* * "*w _ v sine B +u &+= "_ - (-XMTcG q + YMTCGp )V
VMF WMF
UMF _F + V_F VMF + _ WMFFinally, VMF- VMF
.57.3_ 57.3 VMF
BMF = CUfF+ W_F)_Z VMF- VMFCU_FTI.-_-+,MF]_ZVMF
• 57.3 WMF 57.3 UMF°_F- z + z _F 2 + 2 WMF
UMF WMF UMF WMF
A-4
I. Rel_Ort No. ,_ 2. Government Accmsion No. 3. R_il_i4mt's Ca_log No.
NASA CR-172_• 4. Title and Subtitle 5. Report Date
Ausust1984
An In-FlightInvestigationof a Twin Fuselage 6.p_mi.g o,_,,iz,,t_c-,,_Configurationin Approachand Landing
7. Author(s) 8. Perf_min<j Organization Re No.7205-4
norman C. Weingarten10. Work Unit No.
9, PerformingOrglnization Name and Address
ARVI_/CALSPANAdvancedTechnologyCenter 11.con_to,G,_tNo.P.O. Box 400 P.O. L-619668Buffalo,New York 14225 #.Ty_of_el_X't,._d I_ioclCoveted
,_0nzracz0rKep0rz12.spon_i,_A_,cVN,me,_dAddr,u Final Rept. 4/83 - 12/83NationalAeronauticsand Space Administration 14.spo.=_Am_VCo=Washington,OC 20546 505-34-03-03
15s_p_,me,uwyNora Air Force FlightDynamicsLaboratory,Capt. M. Maroney_ontractManaged by: Wright AeronauticalLab., Wright-PattersonAF8, OH 45433NASA TechnicalMonitor: William Grantham,LangleyResearch Center - ContractsF33619-8_-C-3603and F33615-79-C-3618Additionalsupportprovidedby Air Force
16. Absttllct
An in-flight investigationof the flying qualities of a Twin-FuselageAircraft design in the approachand landingFlightPhase was carriedout in theuSAF/AFWALTotal In-FlightSimulator(TIFS). The objectiveof this study was todeterminethe effectsof actual motion and visual cues on the pilot when he wasoffset from the centerline of the aircraft. The experiment variables werelateralpilot offset positon (0, 30, and 50 feet) and effectiveroll mode timeconstant (.6, 1.2, 2.4 seconds). The evaluationincludedthe final approach,flare and touchdown. Lateralrunway offsetsand 15 knot crosswindswere used to
• 2increasethe pilot s workloadand forcehim to make large lateralcorrectionsinthe final portion of the approach. Results indicatedthat large normal acce-lerationsrather than just verticaldisplacementsin rollingmaneuvershad themost significantdegradingeffect on pilot ratings. The normal accelerationsare a resultof large lateraloffset and fast roll mode time constantand causedthe pilot to make unnecessarypitch inputs and get into a coupled pitch/rolloscillationwhile he was making llne-upand crosswindcorrections. A potentialcriteria for lateralpilot offset positioneffects is proposed. When the ratioof incrementednormal accelerationat the pilot stationto the steady state rollrate for a step input (ANz_/Pss)reaches.01 to .02 g/deg/seca deteriorationo,fpilot rating and flyingqualitiesLevel can be expected.
17.K_ W_= (Su_t_bVAut_J"lghtFli 1&Oisvi_ti_SWt=m=.,Twin Fuselage ControlFlyingQualities Approachand Unclassified- UnlimitedRide Qualities Landingbimulation 3taoilityand SubjectCategory08
Control
19. Security Oa_f. (of this regortl _. Securiw Oawf. {of this pa_) 21. No. of Pa_es 22. _e
Unclassified Unclassified 87 A05
,-3os ForsalebytheNat,onalTechnicalInfumationService.Springfield.V=rginla22151
LANGLEY RESEARCH CENTER
3 1176 00518 4727
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