AFFDL-TR-71 -155 Part I TAKEOFF AND LANDING ANALYSIS (TOLA) COMPUTER i2ROGRAM Part I. Capabilities of the Takeoff and Landing Analysis Computer Program URBAN H. D. LYACH, CAPTAIN, US4F TECHNICAL REPORT AFFDL-TR-71-155, PART I FEBRUARY 1972 NATIýXL'T'F ( NI(ALD D C INVOkMATION SErir-CI • •MAY 1 972 Approved for public releaic; distributiou unlimited. B AIR FORCE FLIGHT DYNAMICS LABORATORY AIR FORCE SYSTEMS COMMAND WRIGHI-PA-FFERSON AIR FORCF BAS1E•, OHIO L
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AFFDL-TR-71 -155
Part I
TAKEOFF AND LANDING ANALYSIS (TOLA)COMPUTER i2ROGRAM
Part I. Capabilities of the Takeoff and Landing Analysis Computer Program
URBAN H. D. LYACH, CAPTAIN, US4F
TECHNICAL REPORT AFFDL-TR-71-155, PART I
FEBRUARY 1972
NATIýXL'T'F ( NI(ALD D CINVOkMATION SErir-CI
• •MAY 1 972Approved for public releaic; distributiou unlimited.
B
AIR FORCE FLIGHT DYNAMICS LABORATORYAIR FORCE SYSTEMS COMMAND
WRIGHI-PA-FFERSON AIR FORCF BAS1E•, OHIO
L
NOTICE
When Government drawings, specifications, or other data are used for any purpose
other than In connection with a definitely related Government procurement operation,
the United States Government thereby incurs no responsibility nor any obligation
whatsoever; and the fact ihat the governmeat nmay have formulated, furnished, or in
any way supplied the said drawings, specifications, or other data, Is not to be regarded
by implication or otherwise as in any manner licensing the holder or any other person
or corporation. or conveying any rights orpermissionto manufacture, use. or sell any
patented invention that may in any way be related thereto.
CfST
01C Buf SCrioIUhA
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IVJILM111~tin CODES/
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Co-P i~ (I f th.h4r rejxort mhould not be~ rtitur nod -'inlos4 tre! :T iN rvtuilred 1by -sc 4r Ityc nstr r-it lo.)ZV o'It iC hl A i gitlovlIN, or riotti&t on 14 spee lfi drwo. re ni
UN CLAS SIFýF.DSecurity Classificat on
(Ser"eity 'I.. it",t-." ,, I tll,.,, 1,,,, DO UE. O T O D T .ah.,t- f l - ,d.'~A,,r., -,,,g lw,. -','-d ahe1- the -- 11ai eepur i, cie-ifie~d)S0R IG IN ATI NG A CrTI ýIT Y (Corporate -rhoe) 2P. RLPiO R 7 SEC k I TY L A 551FIIC A T 1ON
Air Force Flight Dynamics Laboratory UNCLASSIFiEDWright-Patterson Air Force Base, Ohio ?ýIRU
3 REPORT TITLE--
TAKEOFF AND LANDING ANALYSIS (TOLA) COMPUTER PROGRAM. PART 1. CAPABILIIIES OF THlETAKEOFF AND LANDING ANALYSIS COMPUTER PROGRAM
4 DESCRIP TIVE NOTES (Týpe of f uepft nd inclusv~e iai-sI
5 AU IHO4RS1 (firs? nameo, middle initial. 'a.t name)
Urban H. D. Lynch, Captain, USAF
6 REPORT DATE 78. TOTAL NO. OF PAGES -]lb. 11O, C- RIFFS
Februa ryr 1972 ___49
StCONTRACT OR GRANT NO 9a, ORIGINATOR'S REPOOIT NUJMBER(S)
h. PROJECT NO 1431 AFFDL-TR-71-155, PART I
Task No. 143109 Ot 0THER REPORTr NOjSI (Any ýItherr-n~bera thafmnuy he asstp...d1th,. repcrt)
d.
II IISIRIOUTIION STATti.IFNT
Approved for public release; distribution unli:nited.
Air Force Flight Dynamics LaboratoryAir Force Systems Command
_____ _____ ___Wright-Patterson Air Force Base, OhioIt AHSINIACT
TOLA is an acronym for a takeoff and landing analysis digital computer program.This part of the report discusses capabilities of the TOLA program.
The program provides a complete simulation of the aircraft takeoff and landingproblem.. Effects simulated in the program include: (I) aircraft control and per-formance during gl ide slope, flare, landing roll, and takeoff roll, a~ll underconditions of changing winds, engine failures, brakt- failures, control systemlai lures, strut fai lures, runway length and control variable limits, and time lags;
l2)anding gear loads and dynamics for aircraft with up to five gears; (3) multipleengine aircraft; (4) engine reversing; (5) drag chute and spoiler effects;(6) braking; (7) aerodynamic ground effect; (8) takeoff from aircraft carriers; and
slope, flare, landing, arnd takeoff can be studied separately or in combination.
Result from) this computer program compared well wi th those of other programsanu actual test res.Ilts. The program is very versatile through its completfness in
s~milaionof the many systems anid effects involved in the takeoff and landjingproblIem. App I:cat ior of TOLA has showni the need f or a tot alI ,ySt ern an alIysis n rce
DI iORIM-1473
Form 1473 Continued:
The TOLA program is ideal for dynamis tradeoff studies inaircrafZ design, landing gear design and landing techniques.The formulation is programmed for both the IBM 7094/7044 IIDirect Couple Computer System in the FORTRAN IV Computer Languageand the CDC 6400/6500/6600 Scope 3.3 Computer System in theFORTRAN EXTENDED Computer Language.
UNCLASSIFI EDSecurity Classification
LINK A LINK E LINK C
KEY WORDS,
ROLE I ROL WT ROLF WT
Takeoff and Landing Analysis
Comp',ter Program
Glide Slope
Flare
Landing Roll
Takeoff Roll
Landing Gear Loads and Dynamics
Vehicle Control
_ __-- iiiii iIIN_ _ _ _ _
_1N C L ASSI F IOU.S.Govornmrnet Printing Office: 1972 - 759-084/1508 S,-, l~t . sL]a kht• Ii,ýn
AFFDL-TR-71-155
Palt I
TAKEOFF AND LANDING ANALYSIS (TOLA)COMPUTER PROGRAM
Part I. Capabilities of the Takeoff and Landing Analysis Computer Program
URBAN H. D. LYNCH, CAPTAIN, USAF
Approved for public release; distribution unlimited.
AFFDL-TR-71-155Part I
FOREWORD
This tvpurt was , L.. ; - r f tý-p plight Mechanr cs e5 "!2,, i,
of the Air Force flight Dynamics Laboratory and the Digital Computation
':vi-ion o0 LiWe Aeronauticai .ysLtes L)ivision, The report was prepared
under Project 1431, "Flight Path Analysis," Task 143109. "Trajectory
and Motion Analysis of Flight Vehicles." The formulation and interim
documentation were completed by Capt. Urban H.D. Lynch. Programming
was accomplished by Mr. Fay 0. Young of the Digital Computation Division
(ASVCP), Computer Science Center, Aeronautical Systems Division.
This report is prepared by Capt Lynch and Mr. John J. Dueweke of the
High Speed Aero Performance Branch (FXG) , and combines the applicable
portions of FDL-TDR-64-l, Part 1, Volume 1, with the interim documentation
prepared by Capt. Lynch.
This report is divided into four parts:Part I: Capabilities of the Takeoff and Landing Analysis Computer
P rogram
Part II: Problem Formulatior
Part III: User's Manual
Part IV: Programmer's Manual
This report was submitted by tie author in November 1971.
This technical report has been reviewed and is approved.
41-PHI P P. ANTONATOSChief, Flight Mechanics DivisionAir Force Flight Dynami--s Lab.
ii
AFFDL-'TR-71-155Pact I
ABSTRACT
TOLA is an acronym for a takeoff and landing analysis digital computer
program. This part of the report d,":.cusses capabilities of the TOLA
program.
The program provides a complete simulation of the aircraft takeoff
and landing problem. Effects simulated in the program include: (1)
aircraft control and performance during giidt slope, flare, landing roll,
and takeoff roll, all under conditions of changing winds, engine failures,
brake failures, control system failures, strut failures, runway length
and control variable limits, and time lags; (2) landing gear loads and
dynamics for aircraft with up to five gears; (3) multiple engine
aircraft; (4) engine reversing; (5) drag chute and spoiler effects;
(6) braking; (7) aerodynamic ground effect; (8) takeoff from aircraft
carriers; and (ý) inclined runways and runway perturbations. The program
is modular so that glide slope, flare, landing, and takeoff can be
studied separately or in combination.
Results from this computer program compared well with those of other
programs and actuai test results. The program is very versatile through
its completeness in the simulation of the many systems and effects
involved in the takeoff and landing problem. Appii,.•Jot, -4 TOLA has
shown the need for a total system analysis since many unexpected results
have been obtained.
AFFDL-TR-71-155
Part I
The TOLA program is ideal for dynamic tradeoff studie!s in aircraft
design, landing gear design and landing techniques. 1he formulation is
programmed for both the IBM 7094/7044 II Direct Couple Computer
S.,tem in the FORTRAN IV Computer Language end the CDC 6400/6500/6600
Scope 3.3 Computer System in the FORTRAN EXTENDED Computer Language.
iv
AFFDL-TR-71- 55Part I
TABLE OF CONTENTS
SECTION PAGC
I INTRODUCTION
II PROBLEM ANALYSIS 3
1. Definition 3
2. Equations of Motion 3
3. Landing Gear 4
1,. Autopilot
5. Computer Output 1L
III ANALYTICAL RESULTS 14
1. Glide Slope 14
2. Flare 17
3. Landirg Roll
4. Takeoff Roll 27
IV CONCLUSIONS
"AFFDL-TR-71 -155
Part I
ILLUSTRAT IONS
FIGURE PAGE
1. C-5A Strut Corfiguration 5
2. Aircraft Autcpilot 6
3. Autopilot Coitrol Systems 7
4. Pitch Autopilot Schematic 11
5. Nominal Glide Slope 15
6. Glide Slope with Headwind Change 16
7. Crossrangc Control with Sidewind Change and Engine 1Failure 16
8. Nominal Flare 18
9. Long Flare 19
10. Short '-]are Crabbed 21
11. Grouno Reaction Pitch Moment 30
12. Pitch Rate 30
13. Pitch Aingle 30
14. Nornal Axis Ground Reaction 30
15. Normal Axis Acceleration 39
16. Mass Center Sink Rate 30
17. Mas. Center Altitude 30
18. Longitudiinal Axis Acceleration 30
19. Runway Velocity .3
20. Tire Deflect ior, Gear 5 31
21. Ground Force, Gear 5 31
22. Strut Velocity, Gear 5 31
23. Strut Displacenent , Gear ! 31
vi
--
AFFDL-TR-71-155Part I
ILL .':TRATION (Cont)
FIGURE PAGE
24. Wheel Axle Moment, Gear 5 31
25. Tire Angular Rate, Gear 5 31
26. Tire Deflection, Gear 3 31
27. Groud Force, Gear 3 32
28. Strut Velocity, C.-ar 3 32
29. Strut Displacement, Gear 3 32
30. Wheel Axle Momtent, Gear 3 32
31. Tire Angular Rate, Gear 3 32
32. Tire Deflection, Gear 1 32
3. Ground Force, Gear I 32
34. Strut Resistance, Gedr I 32
35. Upper Air Chamber Pressure, Gear j 33
36. Strut Acceleration, Gear 1 33
7, S,'ut .elucity, Gear I J3
38. Strut Displacerment, Gear 33
39. Lower Al, Chamber Pressure, Gear 1 33
4U. Secondary Pibton Accelcration, Gear 1 ;3
41 Secondary Piszon Velccitl , Gear I 33
42 Secondary Piston Displacement, '`ear 1 33
43. Wheel Axle Moment, Gear 1 34
44, Tire Ai-jular Rate, Gear I 34
45. Ground Reat.on Pitch Moment 34
4.. Pitch Rate 34
47 P Ltch Ar:qlIe 34
AFFDL-TR-71-155Part I
ILLUSTRArIONS (Cont)
F- I GURE PAGE
48. Normal Axi.L GrOL :d Reaction 34
49. Ma'.s Center Sink Rate 34
rW. Mass Center Altitude 34
51. Runway Velocity 35
52. Tire Deflection, Gear 1
53. Ground Force, Gear 1 35
54. Strut Displacement, Gear 1 35
55. Tire Deflection, Gear 3 35
56. Ground Force, Gear 3 35
57. Strut Displacement, Gear 3 35
58. Tire Deflection, Gear 5 35
59. Ground Force, Gear 5 36
60. Strut Displacement, Gear 5 j6
vii
- - ----- -
AFFDL-TR-71-155Part I
NOMENCLATURE
F-T totai vector force acting on aircraft
MT total mass of aircraft
"• inertial vector acceleration of nominal mass centcr
K number of gears
rnk mass of moving part of kth gear
(Jrkc)k vector acceleration of mass center of "'k relative to aircraft
M-o total vector momeot acting on aircraft about nominal mass center
To aircraf , moment of inertia tenr.or about nominal mass center
uao inertial angular acceleration vector
-- o inertial rotation rate vector
(Rk) vector from nomninal mass center to the wing-gear root of kth gear
rkc vector from winy-gear root to mass center of n)k
ad desired angle of attack
Sqn nominal elevator trim position
(I actual angle of attack
Id a /,.,O da d/dt
Rfa rate feedback constant
Aa allowed angle of attack error
8qd desired elevator position
Ph elevator deflection/error constant
AFFDL-TR-71- i55Part I
SECTION I
INTRODUCTION
The design of an aircraft requires that the landing gear system
be designed to interface properly with the airframe and to be compatible
with other systems affecting takeoff and landing performance. Of these
systems, the primary ones are the landing gear system, the power system,
the elevator control system, and the rudder control system. Usually,
the landing gear design is based primarily on vehicle initial impact;
the power system requirement is based primarily on climb or cruise
performance; elevator size is based primarily on vehicle rotation at
liftoff airspeed; and rudder size is based primarily on engine out
conditions. The final evaluation of all these systems during takeoff and
landing, however, lies in the answer to the question: How do all the
systems perform as a unit? The TOLA (takeoff and landing analysis)
computer program attempts to generalize the aircraft, the capability of
the main aircraft control systems, and the landing-takeoff situation
Into a single comprehensive calculation to answer thit question. The
program does not perform the design function; it simply takes input data
on the systems and computes dynamic results.
The program is very versatile through its completeness in the
simulation of the many systems and effects involved in the takeoff and
landing problem. The following ;ist of complex problems are within
TOLA's capability and are suggestive of its completeness:
a. What effect does limited runway length, changing winds, and
engine failure have on a go-around decision for a particular situation?
AFFDL.-rR-71- 155Part I
b. How does a change in the control schedule for the Iindinq roll
affect maximum gear loads? (Spoiler activation and not initial impact
appears to play a significant roll here.)
c. 'dhat limitations would have to be placed on the landing if one
strut failed to brake or to extend from the fuselage?
d. With multiple engine aircraft and a thrust reversing capability,
is it safe to have some engines in reverse durirng landing in view of
possible engine failure?
V . How nun!ymmetrical can the landing impact be and yet provide an
acceptable landing?
This part of the report discusses the TOLA simulation and its
caprbillties by specific application to the Air Force C-5A aircraft.
AFFDL-TR-71-155Part I
SECTION II
PROBLEM ANALYSIS
I. DEFINITION
In this report, the landing problem Is broken down into four main
areas: glide slope, flare, landing roll, and takeoff roll. For the
glide slope, the basic requirement is to remain near the glide slope
position and come down at a constant inertial speed. For the flare,
the basic requirement is to touchdown at a desired sink rate and landing
speed so as to meet the limitations of expected landing roll distance and
remaining runway length. For the landing roll, the basic requirement,
is to st-quence the spoilers, engine throttle, thrust reversers, drag
chute, and braking to bring the aircraft speed down to the taxi speed.
For the takeoff roll, the basic requirement is to rotate the aircraft
to thý lift-off attitude at the proper airspeed. These requirements
must be met subject to changing winds, control deflection limits and
time lags, aerodynamic ground effect transition, engine failures, and
selected braking failures.
2. EQUATIONS OF MOTION
The equations of motion assume that the main aircraft fr,'rne is rigid;
the dynamic effects of up to five independent landing gears, iowever,
are Included In the equations. Equations I and 2 are the two-vector
rigid-body equations of motion when moving gears are included (for
details see Part !I).
•., a3
AFFDL-TR-71 -155Part I
K
TT T k=i
W 0
3. LANDING GEAR
Thc, landing gear model, shown in Figure 1, is a double air chamber
oleo strut with balloon tires, similar to that used on the C-5A
aircraft. the secondary piston and air chamber can be eliminated from
the problem, if desired. Each of the struts must lie in a plane parallel
to the aircraft plane of symmetry, but the st rut axis may be nonperpendicular
to the longitudinal aircraft axis. The position and velocity of each
strut and secondary piston are obtained by numerical integration subject
to position constraints (for example, the main strut must move within
the limiks of the fully extended position and strut bottom position).
Orifice coefficients can depend on the direction of oil flow through
the orifice. W ntj-qecr root friction (i.e., bindina friction between
moving strut and its support at the wing) is also included. Tire forces
depend upon tire deflection and a coefficient of friction which is a
function of 'percent skid'' (i.e., the ratio of tire footprint velocity
to axle velocity). Thb- simulation iq do{icined to consider that the