nasa contractor report · 2.0 introduction the statement of work for nasa contract nas1-17635, task...

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NASA Contractor Report 1 7 8 1 5 5

(NASA-CE-178155) A U T C M B T I C E E A K I N G SYSTEI3 M87-13446 H D D I F I C A T I O N E C f i THE A C V A N C E I : Z E A N S P O R T O P E E A T I N G SYS!IE M3 (ATCPS) ‘IPAhSECBTATXCN SYSTEMS R E S E A f i C H V L H I C L E (TSIiV) Final Unclas Iieport (Boeinq Commercial A ir f lans Co. ) G3/08 Q3565

AUTOMATIC BRAKING SYSTEM MODIFICATION FOR THE ADVANCED TRANSPORT OPERATING

SYSTEMS (ATOPS) TRANSPORTATION

SYSTEMS RESEARCH VEHICLE (TSRV)

James J . Coogan

BOEING COMMERCIAL AIRPLANE COMPANY S e a t t l e , Washington

C o n t r a c t NAS1-17635 O c t o b e r 1986

National Aeronautics and Space Administration

Langley Research Center Harr?$on,?/i:gin;a 23665

https://ntrs.nasa.gov/search.jsp?R=19870004013 2018-05-27T07:21:49+00:00Z

TABLE OF CONTENTS

1.0

2.0

3.0

TABLE OF CONTENTS

LIST OF FIGURES

SUMMARY

INTRODUCTION

AUTOBRAKE MODIFICATION DESIGN

3 . 1 Background on Current System

3 . 2 Autobrake Arming Logic Modifications

.

3 . 3 Deceleration Control Circuit Modifications

3 . 4 Aft Flight Deck Interface

4.0 SIMULATED SYSTEM PERFORMANCE

4.1 Test Set Up

4.2 Test Conditions

4 . 3 Test Results

5.0 CONCLUSIONS

REFERENCES

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LIST OF FIGURES

TITLE

Autobrake System Overview

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Electrical Schematic of Currently Instal led Autobrake System

Current Autobrake Power Circuit

Autobrake Control Loop

Modified Automatic Braking System Control Circuit

Modified Deceleration Command Circuit

Hybrid Brake Control Laboratory

CV Autobrake Test Setup

Test Matrix

Time History Data, Run 001
















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1 .O SUMMARY

Modifications to the 737-100 autobrake system were designed, under NASA

Contract NAS1-17635, Task 7. These modifications will enable an on-board

flight control computer to control aircraft deceleration to a continuously

variable level, for the purpose of executing automatic high speed turn-offs.

The design problem and proposed solution are described in this report.

A breadboard version of the proposed modifications was built and tested in

simulated stopping conditions. Test results, presented here, show the

effectiveness and limitations of the system.

Implementation on the TSRV 737 and flight testing of the proposed design

modifications is planned for Phase I1 of the program.

2.0 INTRODUCTION

The Statement of Work fo r NASA Contract NAS1-17635, Task 7 , c a l l s for

modification of t h e 737-100 autobrake s y s t e m t o allow continuously variable

deceleration control, i n response t o a deceleration command generated i n an

avionics computer.

system t o automatically b r i n g the a i r c r a f t t o a par t icular speed, a t a

particular spot on the runway, t o allow automatic, high speed t u r n offs .

is required that the modifications do not a f fec t the operation of the

current 3-level autobrake system o r of t h e anti-skid system.

a b i l i t y t o override the automatic system, and related safety features m u s t

be unaffected.

The purpose of t h i s development is t o use t h e braking

It

The p i l o t ' s

Phase I is an engineering s t u d y and modification design.

Control laws fo r automatic deceleration and t u r n o f fs were developed under

an e a r l i e r N A S A Contract (Reference 1 ) . The scheme developed was to use

reverse thrust as the main stopping force, and use the braking s y s t e m for

f ine closed loop deceleration control. Algorithms t o compute the desired

reverse thrust level , and the deceleration command signal were presented i n

.Reference 1, and a re used here. The deceleration command, a t any moment, is

j u s t the average deceleration required t o bring the a i r c ra f t from the

current speed to the desired t u r n speed, i n the amount of space available

before the t u r n .

s ignals.

The signal is ra te limited t o provide smoothly varying

The desired reverse t h r u s t is computed a t the s t a r t of the landing

ro l lou t , on the premise that t h e brakes w i l l not be used t o slow the

a i r c ra f t . Aerodynamic drag and t i r e ro l l ing resistance a re accounted for i n

the comjmtation (presented i n Reference 1 ) . The Statement of Work, and the

earlier contract work provide the context for this design effort. I

2

i i

i -

3.0 AUTOBRAKE MODIFICATION D E S I G N

The d e s i g n o b j e c t i v e is t o e n a b l e t h e a u t o b r a k e sys t em t o c o n t r o l

d e c e l e r a t i o n t o a c o n t i n u o u s l y v a r i a b l e l e v e l .

is t o be a c t i v a t e d when t h e p i l o t selects "VARIABLE", w i t h h i s a u t o b r a k e

control swi t ch , and t h e F l i g h t Con t ro l Computer i n d i c a t e s i t is r e a d y t o

direct t h e brake sys tem. The F l i g h t C o n t r o l Computer w i l l p r o v i d e two

s i g n a l s . The first s i g n a l , CV DECEL ON discrete, i n d i c a t e s t h a t t h e

computer is r e a d y t o direct t h e system. The second is a n a n a l o g s i g n a l ,

which i n d i c a t e s t he desired d e c e l e r a t i o n l e v e l .

The v a r i a b l e b r a k i n g sys t em

I t is r e q u i r e d t h a t t h e m o d i f i c a t i o n s do n o t affect t h e o p e r a t i o n of t h e

c u r r e n t 3 - l eve l a u t o b r a k e sys tem or of the a n t i - s k i d system. The p i l o t ' s

a b i l i t y t o o v e r r i d e t h e a u t o m a t i c sys t em, and related s a f e t y f e a t u r e s must

be u n a f f e c t e d . If t h e p i l o t selects t h e v a r i a b l e a u t o m a t i c b r a k i n g sys t em,

and t h e F l i g h t C o n t r o l Computer is n o t r e a d y t o direct t h e sys t em, t h e

''AUTOBRAKE INOP" i n d i c a t o r lamp s h o u l d l i g h t .

The d e s i g n m o d i f i c a t i o n s can be grouped i n t o 3 categories.

p e r t a i n s t o t h e A f t F l i g h t Deck and its i n t e r f a c e wi th t h e Forward F l i g h t

Deck. A s econd deals w i t h t h e a u t o b r a k e a rming and s a f e t y logic.

p e r t a i n s t o t h e d e c e l e r a t i o n control loop .

One g roup

The l a s t

3.1 Background on C u r r e n t System

F i g u r e 1 is a n o v e r a l l s c h e m a t i c diagram showing o n l y t h e major components

and s i g n a l s of t h e a u t o b r a k e system c u r r e n t l y i n s t a l l e d i n t h e TSRV

a i r c r a r t . Figure 2 is a more d o t i i l o d view shnving external wiring of most

components.

Each stage is part of a separate c i r cu i t and has a separate function. One

stage, wired t o the autobrake c i r cu i t breaker, is used to power the

autobrake system when the p i lo t t u r n s i t on. Another stage connects t h e

autobrake inoperative l i g h t t o its control signal.

one is shown i n Figure 2 , inboard and outboard, a r e ident ica l ) a r e used t o

t e l l the deceleration control cards which se t t i ng the p i lo t has selected.

Note that the autobrake control switch is a multi-stage switch.

Two more stages (only

Figure 3 provides a closer look a t the autobrake power c i r cu i t . When the

p i lo t moves the autobrake switch t o one of the three llON1l posit ions, ( M I N ,

MED, or M A X ) , he powers the autobrake system. Power (28 VDC) from the

autobrake c i r cu i t breaker passes through the brake pedal switches t o the

automatic brake control module. Th i s box contains logic c i r cu i t s t o check

t h r o t t l e positions, brake pressure levels , air/ground sensing, wheel s p i n u p ,

e tc . I t a lso checks for cer ta in e l ec t r i ca l fa i lures . If everything is OK,

the automatic brake control module connects 28 VDC t o the autobrake valves,

and to the "ON RAMP Power" l i n e t o the anti-skid module. "ON RAMP Power"

act ivates the deceleration control feedback system. The autobrake valves

port f u l l hydraulic system pressure t o the anti-skid valves, which control

brake pressure.

Deceleration control is accomplished by the "Selected Decel" cards (see

Figure 4 ) i n the a n t i - s k i d control box. Wheel speed s ignals from the anti-

s k i d cards a re used for sensing, and the control is effected by modulating

brake pressure through anti-skid valves. The decel control card generates a

reference velocity from the measured wheel speeds and the desired

deceleration. The wheel speed error ( the difference between the velocity

r e f e r e n c e and t h e a v e r a g e of the two wheel s p e e d s ) is i n t e g r a t e d t o g e n e r a t e

t h e c o n t r o l s i g n a l , which is s e n t t o t h e a n t i - s k i d v a l v e s . Whenever

n e c e s s a r y , the a n t i - s k i d sys t em can o v e r r i d e that s i g n a l and r e d u c e brake

p r e s s u r e below t h e l e v e l cal led f o r by the d e c e l e r a t i o n c o n t r o l l oop .

The v o l t a g e mode on t h e autobrake card whch r e p r e s e n t s t h e desired

d e c e l e r a t i o n ( a n i n p u t t o t h e v e l o c i t y r e f e r e n c e c i r c u i t ) is c o n t r o l l e d

th rough t h e a u t o b r a k e c o n t r o l s w i t c h (as shown i n F i g u r e 4 ) . The p i l o t se t s

the s w i t c h to M I N , MED, or MAX, which changes t h e resistor network tha t

d e t e r m i n e s t h e d e c e l e r a t i o n command.

3.2 Autobrake Arming Logic M o d i f i c a t i o n s

F i g u r e 5 is a schematic of t h e modified a u t o b r a k e sys tem. The effect of

s e l e c t i n g M I N , MED, or MAX is unchanged. S e l e c t i n g v a r i a b l e decel c o n n e c t s

power t o one c o n t a c t of t h e CV DECEL ON r e l a y . If t h e r e l a y is t u r n e d on by

t h e CV DECEL ON s i g n a l from t h e F l i g h t C o n t r o l Computer, t h e autobrake

sys tem is powered th rough t h e same c i r c u i t s t h a t c u r r e n t l y a c t i v a t e t h e

system. T h i s d e s i g n r e t a i n s a l l of t h e s a f e t y l o g i c b u i l t i n t o t h e

a u t o m a t i c brake c o n t r o l module.

To implement t h e r e q u i r e d au tob rake i n o p e r a t i v e i n d i c a t i o n , we have des igned

a n a d d i t i o n a l s t a g e i n t o t h e au tob rake swi t ch . T h i s s t a g e has t h e wiper

grounded and t h e c o n t a c t co r re spond ing t o t h e VAR s e t t i n g connec ted t h r o u g h

t h e CV DECEL ON r e l a y t o t h e inop l i g h t . If v a r i a b l e decel is selected and

the relay is nnt. t.urned el?, t h e lamp w i l l light.

5

These features can be implemented wi th minor modifications t o the forward

f l i g h t deck and to the a i r c r a f t w i r i n g .

components replaced and added t o the f l i g h t deck panel P2-2. A new

autobrake control switch is required.

be instal led behind the panel i n a mounting plate added for that purpose.

The autobrake control switch wiring is modified s l igh t ly . Also, the l i g h t

plate on the face of the panel is replaced wi th one showing the new

autobrake mode.

Drawing 64-35051 specif ies t h e

The additional relay and diode w i l l

The e l ec t r i ca l connectors on the panel must be rewired t o accommodate three

new signals. The CV DECEL ON s ignal that controls the relay is added, and

the two AUTOBRAKE V A R signals are picked up from the anti-skid box.

3 . 3 Deceleration Control Circuit Modifications

The continuously variable deceleration command is an analog signal picked up

from the experimental P l i g h t control computer. I t is scaled such that 0

v o l t s represents a deceleration of 0 feet/sec/sec, and -10 volts represents

10 feet/sec/sec. An op-amp network was designed t o take t h i s signal and

produce a deceleration signal compatible wi th the operation of the

deceleration control c i r cu i t . Lab t e s t s of the decel control system showed

the relationship between the voltage and deceleration. T h i s relationship

was used i n selecting r e s i s to r values for the op-amp network. ( I t is l ike ly

that some adjustment of some of the r e s i s to r values w i l l be necessary based

on the performance of the system i n f l i g h t t e s t ) . If the automatic brake

control switch is s e t t o V A R , the op-amp network (see Figure 6 ) is connected

t o t h e v e l o c i t y r e f e r e n c e c i r c u i t and sets the d e c e l e r a t i o n i n r e s p o n s e t o

t h e CV DECEL LEVEL s i g n a l gene ra t ed by the f l i g h t c o n t r o l computer , This

ar rangement p r e s e r v e s t h e c u r r e n t l y a v a i l a b l e , 3 - l e v e l autobrake sys t em, b u t

e n a b l e s t he new c i r c u i t t o take c o n t r o l when r e q u i r e d . Note t h a t t h e

d e c e l e r a t i o n c o n t r o l l o o p i t s e l f is u n a f f e c t e d by these changes t o t h e decel

command source .

M o d i f i c a t i o n of t h e selected d e c e l e r a t i o n cards and t h e c o n t r o l box w i l l be

carried o u t by Hydro-Aire D i v i s i o n , Burbank, C a l i f o r n i a , t he s u p p l i e r of t h e

c o n t r o l box.

3.4 Aft F l i g h t Deck and I n t e r f a c e

The a u t o b r a k e c o n t r o l s w i t c h i n t h e a f t f l i g h t deck is n o t connec ted t o t h e

b r a k i n g sys tem. I t is connec ted , t h rough a b u f f e r c i r c u i t i n t h e A f t F l i g h t

Deck I n t e r f a c e , t o t h e C o n t r o l and Command Pane l i n t h e fo rward f l i g h t deck.

The p a n e l i n c l u d e s l i g h t s which indicate t h e s e t t i n g of t h e a f t f l i g h t deck

a u t o b r a k e c o n t r o l swi tch . The m o d i f i c a t i o n d e s i g n fo r t h e a f t f l i g h t deck

and its i n t e r f a c e c a n be summarized as follows:

A , Add VAR s e t t i n g t o t h e au tob rake c o n t r o l s w i t c h .

B. Add a channe l t o t h e b u f f e r c i r cu i t and wi r ing .

C , Add a l i g h t t o t h e C o n t r o l and Command Pane l .

7

The first task is accomplished by replacing the 4-position switch with a 5-

position switch and replacing the light plate that goes with it. The second

requires a complete re-design of the buffer circuit. Modification of the

current buffer circuit is not feasible because it was built with parts that

are no longer available, and because of space constraints on the card. The

third task is as simple as it sounds. There are several unused light

sockets in the panel.

These modifications are covered in Drawing 64-35052.

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4 . 0 SIMULATED TEST C O N D I T I O N S AND RESULTS

Per formance of the aircraft d e c e l e r a t i o n c o n t r o l sys t em and the a l g o r i t h m s

used t o set t h e r e v e r s e t h r u s t command and t h e d e c e l e r a t i o n command was

tested i n a v a r i e t y of s i m u l a t e d o p e r a t i n g c o n d i t i o n s . The test r e s u l t s

d e m o n s t r a t i n g t h e a b i l i t y of the combined sys t em t o a c h i e v e a p a r t i c u l a r

s p e e d a t a p a r t i c u l a r l o c a t i o n o n the runway are p r e s e n t e d i n t h i s s e c t i o n .

4.1 T e s t S e t u p

T e s t i n g was carried out i n t h e Hybrid B r a k e C o n t r o l Simulated Lab a t Boeing.

A " t r i p l e hybr id" s i m u l a t i o n o f t h e T S R V 737 was set up. Ac tua l aircraft

h y d r a u l i c hardware was used t o r e p r e s e n t t i e b r a k i n g system. I

An ana log

computer s i m u l a t e d the h i g h f requency dynamics of t h e sys t em i n c l u d i n g fore-

a f t strut mot ion , wheel speed dynamics, and t h e t i r e -g round i n t e r a c t i o n . A

d i g i t a l computer was used t o s i m u l a t e t he slower f r equency a s p e c t s of t h e

model, s u c h as g r o s s a i r p l a n e motion and aerodynamics , and t o g a t h e r and

store data. F i g u r e 7 shows some features of t h i s f a c i l i t y .

T h i s s i m u l a t e d a i r p l a n e s u p p l i e d i n p u t s i g n a l s t o t h e modified brake c o n t r o l

hardware and responded t o its c o n t r o l s i g n a l s . A 737-100 a n t i - s k i d c o n t r o l

box was used w i t h 2 MKIII a n t i - s k i d cards ( r i g h t and l e f t i n b o a r d wheels),

and one d e c e l e r a t i o n c o n t r o l card ( i n b o a r d ) . The a d d i t i o n t o the

d e c e l e r a t i o n c o n t r o l c a r d was assembled on a bread-board and pa tched t o t h e

card w i t h c l i p leads. A Itone wheel s i m u l a t i o n v 1 was used , meaning t h e wheel

speed dynamics were s i m u l a t e d o n l y once wi th t h e r e s u l t b e i n g fed t o both

a n t i - s k i d cards, and t h e computed ground force scaled up t o r e p r e s e n t a l l 4

wheels.

15

A l lb reakout box" c o n t a i n i n g some of t h e log ic C i r c u i t was b u i l t and

connec ted i n as shown i n F i g u r e 8.

t h e CV DECEL RELAY, t h e a u t o b r a k e i n o p e r a t i v e l i g h t , and o n e r e l a y t o

r e p r e s e n t arming logic i n t h e automatic brake c o n t r o l module.

T h i s box housed t h e a u t o b r a k e swi tch ,

When i n s t a l l e d on the a i r p l a n e , t h e v a r i a b l e decel c o n t r o l sys tem w i l l

r e c e i v e two electrical s i g n a l s from t h e f l i g h t c o n t r o l computer. Both were

provided i n t h e s i r n u l a t i o n by t h e d i g i t a l computer. The CV DECEL ON

discrete c o u l d be set from t h e keyboard or from the s i m u l a t i o n c o n t r o l

p a n e l . The DECEL LEVEL s i g n a l was computed from speed and d i s t a n c e data , as

i n Reference 1 , ( a c c o r d i n g t o e q u a t i o n 1 ) and updated e v e r y 10 msec.

The f o l l o w i n g d e f i n i t i o n s a p p l y :

6 ( t ) - d e c e l e r a t i o n command. COm

'(t) = c u r r e n t a i r p l a n e speed .

= d e s i r e d t u r n speed. 'TURN

= d i s t a n c e a l o n g runway from a r b i t r a r y r e f e r e n c e t o 'TURN

t u r n - o f f .

X ( t ) - c u r r e n t d i s t a n c e a l o n g runway from r e f e r e n c e t o

a i r p l a n e .

The desired r e v e r s e t h r u s t l e v e l was computed before t h e r u n a c c o r d i n g t o

e q u a t i o n 2. T h i s is based on t h e algorithm used i n Refe rence 1 . The factor ,

k , was i n c l u d e d t o v a r y t he r e v e r s e t h r u s t command from t h e v a l u e called f o r by

16

t h e s t o p p i n g c o n d i t i o n s .

r e v e r s e t h r u s t .

The command was l imi t ed t o t h e maximum a v a i l a b l e

2( 1 - T e / t r o l l )

and

ro l l 2 X ~ ~ ~ ~ / ( U o + 'TURN)

The v a r i a b l e s ape d e f i n e d as fo l lows :

F r e v

k

m

"0

"TURN

e '

F~~~~

t ro l l

UR

W

P

'd

r e v e r s e t h r u s t command p e r eng ine .

s c a l i n g factor used t o a l t e r the tes t c o n d i t i o n s .

mass of the a i r p l a n e .

i n i t i a l a i r p l a n e speed.

desired t u r n speed .

time c o n s t a n t of engine r e sponse .

e n g i n e i d l e t h u r s t per eng ine .

e x p e c t e d time from touchdown t o t h e t u r n .

t i re r o l l i n g r e s i s t a n c e factor.

a i r p l a n e weight .

a i r d e n s i t y .

a i r p l a n e wing r e f e r e n c e area.

d r a g c o e f f i c i e n t .

F

1 7

4.2 Test Cond i t ions

The pa rame te r s v a r i e d can be c o n s i d e r e d i n three g roups . The f i rs t g roup

( i n i t i a l speed, t u r n s p e e d and d i s t a n c e t o the t u r n ) is most i m p o r t a n t because

i t d e f i n e s t h e average d e c e l e r a t i o n r e q u i r e d . The second g roup ( t h r u s t l e v e l

and runway mu) has i m p o r t a n t impac t o n t h e a b i l i t y of the b r a k i n g s y s t e m t o

a c h i e v e t ha t d e c e l e r a t i o n .

A 3 - d i g i t c a s e number c l a s s i f i c a t i o n sys t em was a s s i g n e d t o t h e test matrix as

shown i n F i g u r e 9 . The first d i g i t i d e n t i f i e s major classes of c o n d i t i o n s .

For i n s t a n c e , a l l t h e case numbers s t a r t i n g wi th a 4 i d e n t i f y h igh gross we igh t

runs . The l a s t two d i g i t s i d e n t i f y t h e combina t ion of i n i t i a l s p e e d , t u r n

s p e e d , and t u r n d i s t a n c e . Thus , a l l the case numbers end ing w i t h 06 i d e n t i f y

cases w i t h t h e same combina t ion of s p e e d and d i s t a n c e r e q u i r e m e n t s .

The r a n g e of s i m u l a t e d test c o n d i t o n s was based on t h a t o f Re fe rence 1 . The

b a s e l i n e c o n d i t i o n is a 90,000 l b . a i r p l a n e on a d r y runway w i t h no wind, and

t h e t h r u s t command set a c c o r d i n g t o e q u a t i o n 2. The t h r u s t command went from

i d l e t o t h e desired l e v e l one second af ter touchdown, and back t o i d l e when t h e

a i r p l a n e speed was w i t h i n 5 feet/sec of t h e des i red t u r n speed .

of t h e eng ine t o t h i s command was modeled as a first order l a g w i t h a time

c o n s t a n t of 1.3 sec. The i n i t i a l speed is 200 feet p e r s econd (120 k n o t s ) and

t h e d e s i r e d t u r n speed is 110 feet/sec (65 k n o t s ) . The d i s t a n c e from touchdown ,

t o the t u r n o f f is 2300 feet .

The r e s p o n s e

To check out a r ange o f r e q u i r e d d e c e l e r a t i o n s ( r u n s 001 t o 015), i n i t i a l s p e e d

was varied from 110 k n o t s t o 135 k n o t s ; t h e r a n g e of t u r n s p e e d s was between 45

18

k n o t s and 75 k n o t s . D i s t a n c e t o t h e t u r n was v a r i e d from 1800 feet t o 3600

feet , r e s u l t i n g i n r e q u i r e d of ave rage d e c e l e r a t i o n s from 2.6 t o 13.1

feet/sec/sec.

I n most cases, t h e reverse t h r u s t command was set a c c o r d i n g t o e q u a t i o n 1 (as

i n t h e b a s e l i n e case) b u t i n some cases ( r u n s 101 t o 1061, o n l y h a l f t h a t much

t h r u s t was used .

r e v e r s e t h r u s t on t h e a c c u r a c y of t h e sys tem.

t h r u s t makes i t i m p o s s i b l e for t h e b r a k i n g sys t em t o c o n t r o l d e c e l e r a t i o n ) . A

medium range of speed and d i s t a n c e c o n d i t i o n s were r u n for t h e low t h r u s t

test i ng .

These r u n s g i v e a n i n d i c a t i o n of t h e impact of i n a d e q u a t e

(Obvious ly , too much r e v e r s e

Most of t h e c o n d i t i o n s were d r y runway cases, b u t a set of wet runway cases

were s i m u l a t e d ( r u n s 201 to 206). I n t h e s e cases, runway f r i c t i o n was computed

as a f u n c t i o n of a i r p l a n e speed acco rd ing t o T a b l e 2. A medium r a n g e of speed

and d i s t a n c e c o n d i t i o n s were r u n for the wet runway t e s t i n g . I n case 304, t h e

f r i c t i o n l e v e l was set t o . 2 for the e n t i r e run .

The effect of a i r p l a n e weight on system performance was i n v e s t i g a t e d fo r a .

moderate r a n g e of speed and d i s t a n c e c o n d i t i o n s . The b a s e l i n e t e s t i n g was run

a t 90000 l b . l a n d i n g weight . This was v a r i e d t o 70000 l b . ( i n r u n s 504 t o 5 0 9 )

and t o 110000 l b ( i n r u n s 404 to 409). Headwinds and t a i l w i n d s of a b o u t 15

k n o t s were s i m u l a t e d t o e v a l u a t e the i r effect on the d e c e l e r a t i o n c o n t r o l

system. These are t h e 600 and 700 series r u n s .

4.3 Test Results

Table 1 i n Figure 9 shows the effectiveness of the system i n each of the test

conditions. The "speed error" t e l l s how close the system came t o achieving the

desired speed a t the t u r n off .

foot /sec . With few exceptions, the error is l e s s than 1

Time history data for selected cases appears i n Figures 10 through 29. The

data was plotted by a s t r i p chart recorder connected t o the simulator.

the recorder channels display multiplexed signals. One channel shows the

desired t u r n speed as a smooth l ine , compared t o the actual airplane speed,

which is a i r c ra f t deceleration as a smooth curve and the decel command level

w i t h the l i ne connected by brief spikes (see Figure 10).

Two of

An overview of the time history data shows the following trends. The airplane

actual deceleration is usually higher than the commanded deceleration and both

decrease w i t h time. The second effect is a resu l t of the f irst ( i . e . i f the

deceleration exceeds the required leve l , the required deceleration is reduced).

Part of the overshoot is due t o a "deceleration t ransient" a t brake

application. Another contributing factor is tha t , for a constant deceleration

command s e t t i n g , deceleration is a function of speed (because of nonlinearity

i n the wheel speed decoding c i r c u i t ) . I n cal ibrat ing the system, i t was deemed

preferable t o have excess deceleration a t h i g h speed, than t o have insuff ic ient

deceleration a t low speed.

20

Another prominent feature is that t h e braking force remains a t zero for a

substant ia l portion of most runs. T h i s is because the reverse t h r u s t is

providing enough, or more than enough deceleration. The brake system is

effect ively disengaged and can no longer provide closed loop deceleration

control. The deceleration overshoot a t brake application and the algorithm

used t o compute desired reverse t h r u s t combine t o cause t h i s condition. The

cases i n which the reverse t h r u s t command was reduced from the computed value,

provide a better indication of t h e a b i l i t y of the braking system to control

deceleration than the cases i n which the brakes a re disengaged.

Time history also shows that i f often takes about 2 seconds t o get the brakes

off a f t e r t h e airplane a r r ives a t t h e desired spot on the runway.

Runs 001 through 015 cover a wide range of speed and distance requirements.

Only run 010 shows a large error i n speed a t the t u r n off point. I n that case,

the required deceleration was 1 3 feet/sec/sec. Since the decel command is

limited a t 10 feet/sec/sec. and the reverse t h r u s t command is limited t o 8200

l b . per engine, the system d i d not deliver adequate deceleration.

I n r u n s 101 through 106, the commanded reverse t h r u s t was cut by 50% from the

computed value. The speed combinations r u n (see Table 1 , Figure 9 ) required

decelerations between 3.9 and 9.6 feet/sec/sec. I n every case, the speed error

a t the t u r n off was l e s s than 1 footlsec. Comparison of the brake pressure

levels i n these r u n s w i t h those i n t h e previous r u n s having the same speed and

distance combinations, ( r u n s 001 through 006) shows the increased braking

e f fo r t t o compensate for the reduced reverse t h r u s t .

21

Cases 201 th rough 304 were r u n t o i n v e s t i g a t e t h e s y s t e m performance on

s l i p p e r y runways. The r e q u i r e d d e c e l e r a t i o n s were between 3 . 9 and 9.6

feet/sec/sec. I n o n l y one case was t h e s p e e d e r r o r a t t h e t u r n off

s u b s t a n t i a l l y g r e a t e r t h a n 1 foot/sec. I n t h e other case ( r u n 202 for

example ) , t h e low f r i c t i o n l i m i t e d d e c e l e r a t i o n a t h i g h s p e e d , and t h e a n t i -

s k i d system c o n t r o l l e d t h e brake p r e s s u r e . As t h e runway f r i c t i o n b u i l t up ,

e v e n t u a l l y t h e a u t o b r a k e sys t em took o v e r and b rough t t h e a i r p l a n e t o t h e

des i red speed.

I n run 204, t h e high decel case, maximum a v a i l a b l e r e v e r s e t h r u s t was employed ,

b u t t h e wet runway l i m i t e d t h e b r a k i n g force, and t h e r e q u i r e d d e c e l e r a t i o n was

not ach ieved . Compare t h i s time h i s t o r y data t o r u n 004 ( t h e same speed and

d i s t a n c e combina t ion , o n a d r y runway) and n o t e t h e b r a k i n g e f f o r t r e q u i r e d .

Hun 304 a l s o had t h e same s p e e d and d i s t a n c e combina t ions , and was r u n w i t h a

c o n s t a n t runway mu of .2 ( i n c o n t r a s t t o t he mu v e r s u s s p e e d c u r v e used i n t h e

o t h e r wet runway c a s e s ) . Run 304 looks j u s t l i k e r u n 004, i n d i c a t i n g t h a t .2

is enough mu, i f i t is a v a i l a b l e from t h e s ta r t . F i n a l l y , n o t e t h a t n e a r t h e

end of r u n 204, t h e system cal led for and a c h i e v e d , more d e c e l e r a t i o n t h a n on

t h e d r y runway, b u t i t c o u l d n o t compensate for t h e low d e c e l e r a t i o n a t h i g h

speed .

A i r p l a n e weight was shown n o t t o a f fec t t h e sys t em performance. None of t h e

cases run a t 70000 l b . or 110000 l b . r e s u l t e d i n speed errors of s i g n i f i c a n t l y

more t h a n 1 f o o t / s e c . a t t h e t u r n o f f . Speed and d i s t a n c e c o m b i n a t i o n s

r e q u i r i n g d e c e l e r a t i o n s from 3.4 t o 9.6 feet/sec/sec. were r u n a t t h e h i g h

weight ( r u n s 404 t h r o u g h 409) and a t t h e low weight ( r u n s 504 t h r o u g h 5 0 9 ) and

o n l y t h e heavy a i r p l a n e , h i g h d e c e l e r a t i o n case ( r u n 4 0 4 ) t axed t h e System.

22

T h i s is the same speed and distance combination as i n r u n 004 ( a t 90000 lb.)

and 504 ( a t 70000 l b . ) . The effect of the weight variation is seen i n brake

pressure comparisons, because the reverse t h r u s t was s e t t o the l i m i t i n a l l

three cases. I n cases requiring l e s s deceleration (and hence, l e s s reverse

t h r u s t ) , the t h r u s t is not limited, and changes t o r e f l ec t the airplane weight.

.The braking system is not s ignif icant ly affected.

Headwinds and tailwinds of 25 feet lsec. (15 knots) were simulated f o r speed and

distance combinations requiring decelerations between 3.9 and 7.8 feet /sec/sec.

The speed error a t t h e t u r n off i n the tailwind cases ( r u n s 601 t o 603) was

always less than 1 foot/sec. , bu t t he headwinds (in r u n s 701 t o 703) caused low

t u r n off speeds by 3 t o 5 feet isee.

take account of t h e additional drag due t o wind and consequently, cal led for

more reverse t h r u s t than was necessary.

The reverse t h r u s t computation d i d no t

0

n z 0

1%

24

I I

0 I 3 I

H W

a m L 0 3 0

I I 1 I I I I I I I 8 I I I I #

I I I 1 I 4 I I I I I I I I I I I I I I 4 I 1 I I 4 I I I I I I I I I I I I I I I I I I I I 1

25

e W D- cn z IY 3 I-

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. . . . . . . . . . . . . . . o o o o o o o o o o o o o o c o o o o o o o o o o o o o o c C O C O 9 C O m Q ~ C O Q a m Q m o d ~ N m . + c u m " m - 4 N m ~ N ( T

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26

I

Y 200 radlsec-

WHEEL SPEED

0.

3000 psi-

BRAKE PRESSUR

0 .

50 mA

VRLV CURR

0. --

12500

BRAK FORC

E EN

E

. . .

T

l b ..

I NG E

0. -

FIGURE 10 : TIME HISTORV DATA, RUN # 001

27

2000 feet

0 I ST ONCE T O TURN

0.

200 feet/sec --

SPEED A C T U A L / DES I RED U .

10 feetlsec

DECEL COMMANDE ACUTAL

D/

0.

20 Klb forward

E N G I NE THRUST

20 K l b reverse

FIGURE 10 k o n t ' d ) : TIME HISTORY DATA. RUN ~ 0 0 1

I

4

200 rad/

WHEEL SPEED

0. -

'sec

- 3000 psi

BRAKE PRESSURE

i : : : ! : : : : : : : : : : : : : : :

VALVE CURRENT

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 l 1

I " " " " " " " '

12500 l b

BRAK I NG FORCE

0.

FIGURE 11 : TIME HISTORV DATA, RUN #002 __

29

2000 feet

DISTANCE T O TURN

0.

200 feetlsec

SPEED A C JUAL/ DESIRED U .

10 feet/sec

DECEL CUMVANDED/ A C U h i

0. t : : : : ; : : : : : : : : : : : : : : :

20 K1 b forward

ENG I NE THRUST

20 K1 b reverse

FIGURE I ! (cont'dl: TIME HISTORY DATA, RUN -~

30

200

WH SP

0.

rad/sec

EEL EED

3000 psl

BRAKE PRESSURE

0.

VALVE

12500 lb

BRAK I NG FORCE

0.

c - 5 s e c 4

FIGURE 12 : TIME HISTORV DATA. RUN 800003

31

2000 feet

DISTANCE T O TURN

0. - -

200 feet / sec

SPEED A C T U A L / DES IRED U .

IO feetlsec ~

SECEL COMVANDED/ GCU7 HL

0.

20 Klb forward

ENG I NE THRUST

20 Klb reverse 1 1 1 1 1 1 1 1 1 1 1 1 ,

FIGURE 72 (cont'd): T I M E HISTORV DATA. RUN SO03

200 rad/sec .

1 1 . I

WHEEL SPEED

3000 psi -.-.

BRAKE PRESSURE

..

0 . -- ...

V A L V E PI IDDCLIT b U l \ I \ L I . I

0 _-

BRAKING FORCE

0 .

FIGURE 13 : TIME H I S T O R V DATA, RUN ~00' f - -

3 3

2000 feet

DISTANCE T O TURN

0. --

ZOO feet/sec

SPEED A C T U A L / DESIRED u. -

10 feet/sec

-- .

- . .

DECEL COMPANDED/ A X 7 h i

- .- 0.

20 K1 b forward

ENGINE THRUST

20 Klb reverse

FIGURE I3 (cont Id) : T IME HISTORY DATA, RUN *oOcf

34

200 rad/sec

WHEEL SPEED

0 . - .. - __ 3000 psi

BRAKE PRESSURE

0 .

50 mA

Val VF W I IL v L

L U K K t N 1

0. -

12500 l b

BRAK I NG FORCE

-_

0 . 1 , , 1 , , 1 ,

5 sec

I

FIGURE14 : TIME HISTORY DATA, RUN ~ 0 1 0

I 35

2000 feet

D I S T A N C E T O TURN

0.

200 feetlsec -

SPEED ACTUAL/ DES I RED U .

10 feetlsec

DECEL COMtlANDED/ A W 7 h i

0.

20 Klb forward

ENGINE THRUST

20 Klb reverse

I ' I l l 1 1 I I I 1 1 1 - 1

& S set+ FIGURE 14 (cont Id): T I M E HISTORY DATA. RUN ~ O l O

- - -

36

i

1

I

200 rad/sec

WHEEL SPEED

0.

3000 psl

BRAKE PRESSURE

0.

12500 lb-

B R A K I N FORCE

0.- --

G

FIGURE IS : TIME HISTORY DATA, RUN *to15

3 7

!OOO feet

I I S T A N C E ro TURN

3 .

200 feetlsec

SPEED RCTUAL/ DESIRED 0.

10 feetlsec-

'SECEL COMtWNDED A C G I h i

/

0.

20 Klb foruard-

ENG I NE THRUST

I 20 K1 b reverse

5 sec '-1- FIGURE15 ( con t ' d ) : TINE HISTORY DATA, RUN 8015

L

38

-~~ ~~

~

200 rad/sec

WHEEL SPEED

0. - . .

3000 psi

B R A K E P R E S S U R E

0. -

50 mA

VALVE CURRENT

B R A K I N G FORCE

0. -

. ... .

.

__

. .. .

39

2000 feet - . .

DISTANCE T O TURN

.. .

- - ..

200 feet/sec

SPEED A C T U A L / DES I RED u. -

t : : : : : : : : : : : I : : : i 10 feet/sec ~~

DECEL COMMANDED/ ACUTAL 0.

20 Klb forward

ENGINE THRUST

20 Klb reverse I I I 1 1 1 I 4 I I 1 t . L - . I

5 sec

FIGURE 16 (cont'd): TIME HISTORV DATA, RUN 8101

40

200 rad/sec

WHEEL SPEED

0. -

-- .

. - . -

3000 PSI -- -.

BRAKE PRESSURE

0 .

50 mA -

VALVE CURRENT

0.

ORIGWAL PAGE IS OF POOR QUALITY

12500 l b -

BRAKING FORCE

2000

D I S T O

0.

feet -~

ITANCE TURN

200 feet/sec

SPEED A C T U A L / DES I RED

10 feet/sec

DECEL CDRT?ANDED/ G U 7 h i

E N G I NE THRUST

20 K1 b reverse

L s s e c 4

FIGURE 17 (cont'dl: TIME HISTORV DATA, RUN 8103

4 2

200 rad/

WHEEL SPEED

0 - -

'sec

- 3000 PSI

BRAKE PRESSURE

0. -- - - ...

50 mA

VALVE CURRENT

12500 l b -

BRAK I NG FORCE

0 ,

ORiGfNAL PAGE IS OF POOR QUALIW

L 5 s e c 4

FIGURE 18 : TIME HISTORV DATA, RUN a loq

4 3

2000 feet -

D I STANCE T O TURN

0. -. -~

200 feetlsec

SPEED ACTUAL/ DES I RED U.

10 feetlsec _ _ _ -

DECEL CBMI?ANDED/ GCG7 h i 0.

20 K1 b foruard

E N G I NE THRUST

20 K1 b reverse I I I I I I I

5 sec

FIGURE 18 (cont'd): TIME HISTORY DATA, RUN

44

ORIGINAL PAGE ts OF POOR QUALITY

200 rad/s

WHEEL SPEED

;ec

0 - - 3000 PSI -

BRAKE PRESSUR

0.

50 mA -

VALVE CURREN

E

T

0. --

12500 lb -

BRAK I NG FORCE

0.

I FIGURE 19 : TINE HISTORV DATA, RUN SI06 I . - I - I

45

2000 feet -

D I STANCE T O TURN

0. ---

200 feet /sec -

SPEED ACTUAL/ DESIRED u. --

10 feetlsec-

DECEL COMMANDED ACUTAL

20

EF T t

20

Klb for

J G I N E i R U S 1

K l b re\

.ward

rerse 1 I 1 I 1 1 1 1 1 1 1 1 l

FIGURE 19 (cont ' d ) : TIME HISTORY DATA. RUN 8 /06 J *

46

i Y

I

Y

200 rad/sec

WHEEL SPEED

0.

ORIGINAL PACE rs OF POOR QUAlItY

3000 PSI

BRAKE PRESSURE

-- SO mA

V A L V E CURRENT

12500 lb --

BRAK I NG FORCE

FIGURE 20: TIME HISTORY DATA, RUN

47

2000 feet --___

DISTANCE T O TURN

0. -

200 feet/sec

SPEED A C T U A L / DES I REO

10 feetlsec - _ _ _ - -

DECEL COMMANDED/ ACUTAL

20 Klb forward

ENG I NE THRUST

20 Klb reverse

L5 secJ

FIGURE 20 (cont ' d ) : TIME HISTORY DATA. RUN # 201

48

v

-

L

v

ORlGlNAL PAGE *IS IoF POOR QUALITY

FIGURE 21 : TIME HISTORV DATA. RUN st 202

2000 feet


0 . - _ _ _

200 feetlsec _ _ _ -

SPEED ACTUAL/ DES I RED U .

10 feethec --

DECEL COMMANDED/ ACUTAL

20 K1 b forward

E N G I NE THRUST

20 K1 b reverse

200 rad/sec -

WHEEL SPEED

3000 psl -

B R A K E P R E S S U R E

0 . -_

V A L V E CURRENT

0.

12500 l b - - . . -

ORIGINAL PAGE rs OF POOR Q u A L l N

1 I , , , , I , , , , , , , ' 1 " ' " " " " ~

. .. ..

B R A K I N G FORCE

0. -

FIGURE22 : TINE HISTORV DATA, RUN 8204

51

2000 feet - -

D I STANCE T O TURN

0. . . . .

200 feet/sec

SPEED A C JUAL/ DES I RED U .

10 feet/sec

DECEL COMMANDED/ QCUTAL 0.

20 Klb foruard

ENG I NE THRUST

20 K1 b reverse

FIGURE22 (cont'd): T I M E HISTORV DATA. RUN

52

200 rad/sec --

WHEEL SPEED

0. .-- 1 , u ! 1 : : : : : : . , , v . Q '

, 1 1 1 1 "

3000 PSI - -

BRAKE PRESSUR

0 . --

- -- I , . . . .

- I . . . . .

50 mA -----

CURRENT

12500 l b .

FIGURE23 : TIME HISTORY DATA. RUN s 3 O q -

5 :

2000 feet

DISTANCE T O T U R N

200 feet/sec

SPEED A C T U A L / DESIRED U .

10 feetlsec -

DECEL COMMANDED ACUTAL 0. --

20 Klb forward

ENG I NE T H R U S T

20 K1 b reverse

k 5 s e c 4

FIGURE 23 (cont Id ) : T I M E HISTORY DATA, RUN 30q

5 4

200 rad/sec .

WHEEL SPEED

0.

3000 PSI -

BRAKE PRESSURE

--

VALVE CURRENT

1 1 1 1 1 1 1 1 1 1 1 1 1 I l l . , , I .

50 mA -

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

I " " t

0.

12500 l b

BRAK I NG FORCE

0.

FIGUREZY : TIME HISTORV DATA, RUN *rqoLf

55

2000 feet -

0 I STANCE T O TURN

0.

200 feetlsec

SPEED ACTUAL/ DES I RED u. -

10 feet/sec --

DECEL COMMANDED/ G C U 7 AL

..

0.

20 K1 b forward

ENG I NE THRUST

20 K1 b reverse

---r I I I 1 I , 1 1 , , , 1 , ,

k5 s e c 4

FIGURE 2Lt lcont ' d ) : TIME HISTORV DATA, RUN 8 4w

200 radlsec

WHEEL SPEED

0.

ORfGfNAL PAG:" i? OF POOR QUALITY

3000 psi

BRAKE PRESSURE

50 mA

VALVE CURRENT

0. ---- I : : ! : : ! : ! ! ! : ! ! : ! : i f ! ! ! I : ! !

12500 lb --.--

BRAKING FORCE

0.-

FIGURE 25 : TINE HISTORV DATA, RUN * q 0 7

57

2000 feet -

DISTANCE T O TURN

200 feetlsec

SPEED ACTUAL/ DESIRED 0.

10 feetlsec -

DECEL COMPANDED/ ACUTAL

20 K1 b foruard

THR

20 K

ENGINE JST

b reverse

58

I Y

i v

c

.v (

200 rad/sec . .-

WHEEL SPEED

0.

3000 psl

BRAKE PRESSURE

0 .

50 mA

VALVE CURRENT

0.

I C W U Ib

I . . . . . .

FIGURE 26 : TIME HISTORV DATA. RUN *SO‘/ _ _

59

60

2000 feet -


. -- 0. -

1 1 - - 1 1 I I I I 1- I - ' ' ' ' ' '

200 feetlsec

SPEED ACTUAL/ DES 1 RED 0.

10 feetlsec

OECEL COMMANDED/ GCUTAL 0.

20 Klb forward

ENGINE THRUST

20 K1 b reverse

FIGURE 2 6 (cont 'd): T I M E HISTORV DATA, RUN asoq

-- _ - -

ORIGINAL PAGE *E OF POOR QUALIN

200 rad/sec

WHEEL SPEED

0.

3000 psl -

BRAKE PRESSURE

V A L V E C U R R E N T

0. ---- 12500 lb --

BRAKING FORCE

0. ---

FIGURE 27 : TIME HISTORV DATA, RUN ~ 5 0 9

61

2000

DlS T O

0. -

feet

I T A N C TURN

200 feet/sec

SPEED A C T U A L / DES I R E D

-... . u. -

10 feetlsec -

DECEL COMMANDED G C U T N

20 K l b forward

ENGINE THRUST

20 Klb reverse

I I , , , , l--T--T--l 1 1 - - - T - - r - - 7 1 - 1 I , I , , I I - -r-

FIGURE27 (cont 'd ) : TIME HISTORV DATA. RUN =507

6 2

I

Y

ORIGINAL PAGE -:S OF POOR QUALITY

200 rad/sec -

WHEEL SPEED

0.

- -w

3000 psl

B R A K E PRESSURE

0.

50 mA

VALVE CURRENT

0.

B R A K I N G FORCE

FIGURE28: T IME HISTORV DATA. RUN * b o { -

63

64

2000 feet -

DISTANCE T O TURN

0.

200 feetlsec

SPEED ACTUAL/ DESIRED

10 feetlsec

DECEL COMMANDE ACU TAL

. n -

D /

.

20 K1 b forward

ENG I NE THRUST

20 K1 b reverse

b 5 s e c d

FIGURE 28 (cont Id): T I M E HISTORV DATA, RUN ~ 6 0 1

FIGURE29 : TIME HISTORV DATA, RUN 8 701 I

6 5

2000 feet

DISTAN T O TUR

0 . -

CE N

200 feetlsec

SPEED A C JUAL/ DES I RED U.

10 feetlsec

DECEL COMVANDE ACUPAL 0.

D/

20 K1 b foruard

Tt

20

ENG I NE RUST

Klb reverse - - I - . , 1 I * , , I I -

5 sec

FIGURE29 (cont'dl: T I M E HISTORY DATA. RUN "701

66

5.0 CONCLUSIONS

The m o d i f i c a t i o n s des igned under t h i s c o n t r a c t and p r e s e n t e d i n t h i s r e p o r t

w i l l e n a b l e t h e research f l i g h t c o n t r o l computer t o c o n t r o l d e c e l e r a t i o n

d u r i n g l a n d i n g r o l l - o u t i n such a way as t o b r i n g t h e a i r c ra f t t o a desired

speed a t a p a r t i c u l a r s p o t on t h e runway f o r t h e purpose e x e c u t i n g

a u t o m a t i c , h i g h speed turn-off 's .

The r e q u i r e d m o d i f i c a t i o n s are summarized as f o l l o w s :

A R M I N G LOGIC

Add a new s e t t i n g (VAR f o r v a r i a b l e , i n a d d i t i o n t o t h e

c u r r e n t OFF, M I N , MED, MAX s e t t i n g s ) t o t h e a u t o b r a k e c o n t r o l

swi tch i n t he forward f l i g h t deck, and a relay for sa fe ty l o g i c .

DECELERATION CONTROL

Modify t h e s e l e c t e d d e c e l e r a t i o n c o n t r o l cards i n t h e

a n t i - s k i d box t o respond t o t he c o n t i n u o u s l y v a r i a b l e

d e c e l e r a t i o n command.

AFT FLIGHT DECK AND INTERFACE

Add t h e VAR s e t t i n g t o t h e autobrake cont re l switch aiid add

67

a corresponding channel t o t h e communication network between

a f t and forward f l i g h t decks.

Two aspects of the performance of t h e proposed continuously variable

decleration control system m u s t be emphasized. Due t o t h e time response of

the deceleration control loop, i t takes two seconds t o re lease the brakes

a f t e r the deceleration command goes t o zero. To avoid braking d u r i n g the

turn-off, i t is recommended t h a t algorithm used t o compute t h e deceleration

command take account of t h i s de lay . Secondly, the system does not provide

v e r y precise deceleration control. The discrepancy between the command and

the actual deceleration w i l l often exeed 1 foot/sec/sec. However, the

system implemented i n these simulated t e s t s does provide the desired r e s u l t s

i n terms of speed and distance.

68

REFERENCES

( 1 ) Pines, S., "Terminal Area Automatic Navigation, Guidance, and Control

Research Using the Microwave Landing System (MLS)", - NASA CR-3451,

August, 1981.

69

Standard Bibliographic Page

Report No. 12. Government Accession No.

NASA CR-178155

AUTOMATIC BRAKING SYSTEM MODIFICATION FOR THE ADVANCE1 TRANSPORT OPERATING SYSTEMS (ATOPS) TRANSPORTATION SYSTEMS RESEARCH VEHICLE (TSRV)

Title and Subtitle

James J. Coogan Author( s)

__ , Performinn Organization Name and Address Boeing Commercial Airplane Company A Division of The Boeing Company Seattle, Washington 98124

2 . Sponsoring Agency Name and Address National Aeronautics and Space Administration Washington, DC 20546

3. Recipient's Catalog No.

5. Report Date

October 1986 6. Performing organization Code

- 8. Performing Organization Report No.

D6-38012 10. Work Unit No.

11. Contract or Grant No.

NASl-17635 -- 13. Type of Report and Period Covered

Contractor Report - 14. Sponsoring Agency Code

505-45-33-04 5 . Supplernentary Notes Langley Technical Monitor: James C. Young Final Report - Task 7

6 Abstract Modifications were designed for the B-737-100 Research Aircraft autobrake system hardware of the Advanced Transport Operating Systems (ATOPS) Program at Langley Research Center. These modifications will allow the on-board flight control computer to control the aircraft deceleration after landing to a continuously variable level for the purpose of executing automatic high speed turn-offs from the runway. tested in simulated stopping conditions. Test results, for various aircraft weights, turnoff speed, winds, and runway conditions show that the turnoff speed are achieved generally with errors less than 1 ft/sec.

A bread board version of the proposed modifications was built and

17. Key Words (Suggested by Authors(s))

Automatic Braking Automatic Control

. . ~ ____.--~_ - I!]. Security CIassif.(of this report) 20. Seciirit,

- 18. Distribution Statement

Unclassified - Unlimited

Unclassified 73 A04 - _- -. _ _ 1- -Vnclassified --I- -. - ~ -1- - -- -- - -

For sale by the National Technical Inlormsriori Service, Springfield, Virgiiiia 22161 N 4 d A Langley k'orm 61 (June 1985)

nasa contractor report · 2.0 introduction the statement of work for nasa contract nas1-17635, task...

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