ESTABLISHING CONFIDENCE IN CCV/ACT TECHNOLOGY

Richa rd B . Holloway and Henry A . Shomber The Boeing Company

Despite s ign i f icant advancements i n Controls Configured Vehicles/Active Controls Technology (CCV/ACT) i n the past decade, few ap-plications of t h i s promising technology have appeared i n recent a i r c r a f t designs. This paper b r i e f l y summarizes the s t a t u s of CCV/ACT, describes some of the cons t ra in ts which a re re tarding i t s wider application, and of fers some suggestions toward establ ishing an increased l e v e l of confidence i n the technology.

I”E3 ODUC TION

Major advancements have been accomplished i n f l i g h t control technology during the pas t decade, pa r t i cu la r ly i n the areas of fly-by-wire, act ive controls and, more recent ly , d i g i t a l controls. The next generation of U. S . commercial t ransports must take advantage of benef i t s achievable from these advanced techniques t o remain competitive i n the world market. European a i r c r a f t indus t r ies have major advanced f l i g h t cont ro l programs underway and are making s igni f icant progress i n t h i s f i e l d . The United States space program, research a i r c r a f t programs and mi l i ta ry advanced development programs have brought ACT d i g i t a l F B W (fly-by-wire) technology t o a l e v e l where subs tan t ia l benef i t s can be real ized i n the near future . Hodever, the commercial a i r c r a f t industry, a i r l i n e industry, and government c i v i l av ia t ion agencies must be convinced t h a t an a i r c r a f t designed around t h i s advanced technology w i l l achieve predicted performance and be safe, r e l i ab le , operationally p rac t i ca l and cost e f fec t ive . Commercial acceptance of any new technology w i l l occur only when suf f ic ien t t e s t data are generated t o c l ea r ly demonstrate t ha t these c r i t e r i a can be met with reasonable r i s k on a new airplane design.

Most of the progress to date i n t h i s f i e ld has been accomplished primarily on four a i r c r a f t : these a i r c r a f t a r e making s igni f icant necessary contributions, but the programs a r e experimental i n nature, conducted t o demonstrate concept f e a s i b i l i t y under carefu l ly r e s t r i c t ed f l i g h t conditions in evacuable mi l i ta ry a i r c r a f t with e jec t ion sea ts . This paper b r i e f l y summarizes the s ta te-of- the-ar t of CCV/ACT technology and suggests some approaches t o the problem of developing a w i d e r l e v e l of confidence i n tha t technology.

the XB-70, B-52, F-4 and F-8. Programs on

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https://ntrs.nasa.gov/search.jsp?R=19760024074 2020-04-28T13:53:24+00:00Z

BACKGROUND

I n the past decade, po ten t i a l benef i t s of advanced f l i g h t control technology have been shown by a la rge number of t heo re t i ca l analyses and by several USAF and/or NASA f l i g h t demonstration programs. Table I summarizes b r i e f l y the r e s u l t s of most of these e f f o r t s . References 1 and 2 provide a more complete summary.

Major A i r Force experimental f l i g h t research programs involving load a l l ev ia t ion and fat igue damage r a t e reduction by s t r u c t u r a l mode control techniques were the B-52 LAMS (Load Alleviat ion and Mode Stab i l iza t ion) and the XB-70 GASDSAS (Gust Alleviat ion and S t ruc tura l Dynamic S t a b i l i t y Augmentation System) programs. system (SAS) was developed and incorporated on the B-52G and H f lee t t o reduce fat igue damage r a t e during low level , high speed f l i g h t . The A i r Force Control Configured Vehicle (CCV) research program has completed f l i g h t demonstration of four ACT concepts a t selected f l i g h t conditions on a B-52E a i r c r a f t : r i d e control, f l u t t e r mode control , maneuver load control, and augmented s t a b i l i t y . I n addition, the compatibil i ty of a LAMS system with these four concepts was a l s o demonstrated.. Goals fo r each concept were successful ly achieved individually and co l lec t ive ly during the program.

Concurrently, an advanced s t a b i l i t y augmentation

Other f l i g h t programs have incorporated limited ACT concepts i n recent ly designed mi l i ta ry and commercial a i r c r a f t . Reduction of l a t e r a l gust l o a d s on the L-1011 t ransport with an advanced yaw damper resul ted i n a 20 percent reduction of l i m i t design loads. been developed f o r the 747 t o improve passenger r ide qua l i t i e s i n the a f t section. The system is current ly being evaluated by @ntas Airways. A r i d e control system i s being designed for the B-1 s t r a t eg ic bomber, using s t ruc tu ra l mode control techniques, t o improve crew r i d e qua l i t i e s during t e r r a i n following missions. An Active L i f t Distr ibut ion Control System (ALDCS) i s being designed f o r t h e C-5A a i rplane t o reduce wing design l i m i t maneuver and gust loads and wing fat igue damage r a t e a The General Dynamics prototype lightweight f igh te r , the YF-16, has a quadruply-redundant analog, FBW control system without mechanical backup. Relaxed inherent s t a b i l i t y is integrated in to the a i r c r a f t design t o reduce drag and gross weight,

A Gust Response Suppession System has

The f i r s t serious commitment t o including an ACT concept ir, a commercial t ransport occurred during the recent National SST program. The SST was configured with relaxed longi tudinal s t a t i c s t a b i l i t y t o achieve necessary gains i n range-payload from reduced gross weight and drag. Experience gained from development of f a i l -pas s ive and f a i l-opera t i onal/fa i l -pas s ive autoland systems a t Boeing during the 1960's provided confidence tha t a su i tab le f l i g h t cont ro l system could be developed t o meet SST safe ty and operational requirement

The resu l t ing SST longi tudinal command and s t a b i l i t y augmentation system providing basic a i rplane safe ty was fai l -operat ional squared (fai l -operate a f t e r second f a i l u r e ) channels and actuators e ( a discussion of t h i s system is contained i n Reference 3)

u t i l i z i n g quadruply redundant sensors, analog e lec t ronic A mechanical reversion back-up mode was retained

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Cancellation of the SST program precluded thorough development and f l i g h t test evaluation of the SST f l i g h t control system. which include electronic display and control system components were, however, government funded f o r fur ther development under the DOT/SST Technology follow- on program (Contract DOT-FA72-WA-2893).

Advanced technology items

Fu l l r ea l i za t ion of advanced cont ro l function po ten t i a l on production air- craft depends on fly-by-wire cont ro l systems with a r e l i a b i l i t y consis tent with the function c r i t i c a l i t y . Two programs, the A i r Force F-4 680J Survivable Fl ight Control System and the NASA F-8C d i g i t a l fly-by-wire program, a re directed toward developing and f l i g h t demonstrating F B W systems on f igh te r a i r c r a f t . completion of the 6805 f l i g h t tes t program, analog fly-by-wire control techniques, equipment mechanization and fundamental c r i t e r i a a r e now f u l l y validated I t .

A s a r e s u l t , Reference 4 s t a t e s t ha t "with successful

Most advanced FBW f l i g h t cont ro l systems have used analog implementation techniques. Research is now underway t o exploi t the advantages of d i g i t a l control, demonstrated, i n pa r t , by the Apollo space program. The recent extremely rapid progress i n microcircuitry has made d i g i t a l control hardware competitive with analog hardware i n terms of cost , r e l i a b i l i t y , s ize and weight. Further, d i g i t a l techniques of fe r s ign i f icant advantages fo r advanced cont ro l laws, redundancy logic and b u i l t - i n t e s t ing functions. One of the first programs t o study d i g i t a l f l i g h t control implementation problems on a i r c r a f t is the NASA F-8 program which successfully demonstrated a s ingle channel d i g i t a l F B W primary f l i g h t control system with a t r i p l y redundant analog backup system. Dig i ta l Avionics Integrated Systems (DAIS), the SST Follow-On Technology, a rd the planned Tact ical Ai rcraf t Dig i ta l System (TADS), are contributing t o t h i s technology base. Other A i r Force programs a re invest igat ing the appl icat ion of multiplexing techniques t o f l i g h t control systems. Further, research e f f o r t s within the U. S. and European f l i g h t control system component manufacturers a re studying f ibe r op t ics fo r providink s igna l transmissions immune t o electromagnetic interference.

Other d i g i t a l cont ro l research programs, such a s the

An ove ra l l assessment of advanced f l i g h t control technology over the past decade indicates t h a t considerable progress has been achieved:

o Performance of CCV functions has been f l i g h t demonstrated on a large f l ex ib l e a i r c r a f t

o Dig i t a l and analog FBW systems have been f l i g h t demonstrated on f igh te r aircraft

o A prototype lightweight f igh te r has been designed around CCV analog FBW techniques.

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CONSTRAINTS ON THE USE OF CCV/ACT TECHNOLOGY

Despite the large amount of ana ly t ica l and f l i g h t t e s t d a t a available, no CCV/ACT concepts a re current ly i n general use i n commercial transport a i r c r a f t . Only the simplest form of augmented s tabi l i ty-- the yaw damper-- is i n widespread use i n commercial a i r c r a f t today. Primary applications a re t o improve handling qua l i t i es and t o increase the comfort l eve l of the crew and passengers. I n a few instances, a yaw damper was necessary fo r ce r t i f i ca t ion . Although these a re examples of beneficial applications, the systems were generally added a f t e r the airplane was designed, sometimes a f t e r the f irst model flew. I n most instances, a much greater benefi t would have been possible if a full-t ime d i rec t iona l s t a b i l i t y augmentation system had been assumed from the beginning of the design.

There are a number of constraints t h a t have e f fec t ive ly delayed the wide- spread implementation of these systems. A most fundamental constraint is r i sk , pr incipal ly on the par t of the airframe manufacturer. A s has been pointed out, the maximum potent ia l benefi t of these advanced concepts i s achieved i f they are incorporated in to the design a t the outset . However, the f i n a l assessment of the benefi t r e su l t s from an exhaustive design process t h a t i s expensive and time consuming, and f o r which the correlat ion with hardware r e s u l t s is not a t a l l cer ta in . The r e a l r i s k i s tha t a major problem may a r i s e a f t e r program commitment of an airplane design predicated on successful system performance.

Figure 1, reproduced from Reference 46, i l l u s t r a t e s t h i s concern. A t program go-ahead, with only 3% of the eventual t o t a l program cost ac tua l ly spent, management act ion can influence t o t a l program cost by 20% a t most. Consequently, a program tha t r e l i e s on advanced systems w i l l e i t he r require a s ignif icant increase i n analysis confidence, or a program structure l i ke the U. S. SST where an engineering prototype precedes production commitment. I n other words, one way of eliminating the r i s k is t o have a "proof before use" program plan, which adds t o program time and cost .

Another constraint i s the cost of these systems, including development, certif : ication, and maintenance cost . Bright spots i n the cost picture a re the rapidly developing f i e ld of d i g i t a l systems for a i r c r a f t applications and the reductions i n analog/digital system cost dispar i ty .

A th i rd constraint is the lack of confidence i n the analysis too ls and the correlat ion between ana ly t ica l models and the r e a l world. For example, i f a new airplane were t o depend on f l u t t e r mode control fo r f l u t t e r safety, there would be l i t t l e margin f o r error between the ana ly t ica l model and the hardware. Yet the s t a t e of the a r t of f l u t t e r analysis can accomplish t h i s today ,only by "fine tuning"' the analysis with hardware data.

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A f i n a l constraint is the reluctance on the pa r t of the user, the a i r l i nes , t o increase maintenance costs . Consequently, there i s great reluctance t o buy a system, almost independent of i t s performance benefi ts , unless there is a proven method of keeping the maintenance burden i n hand.

It i s generally t r u e t h a t maintenance cons t i tu tes about one-quarter of t he t o t a l d i r ec t operating cos ts f o r current a i rplanes. Therefore, complexity such as d iscussed here should be accompanied by systems designed t o hold the l i ne on, or lower, maintenance costs . Digi ta l systems, with improved self- check capabi l i ty , may provide a solut ion t o t h i s problem.

REMOVING THE CONSTRAINTS : DEVELOPING CONFIDENCE

Commercial r ea l i za t ion of the benefi ts associated with advanced control concepts w i l l occur only when these constraints are removed through compre- hensive development and demonstration of necessary methods and components.

Fl ight Demonstration

Most of the progress t o date i n t h i s f i e l d has been accomplished primarily on four a i r c r a f t : the B-52, F-4, F-8 and XB-70. Programs involving the mi l i ta ry a i r c r a f t are making s igni f icant necessary contributions, but the programs a re experimental i n nature, conducted t o demonstrate concept f e a s i b i l i t y under carefu l ly r e s t r i c t ed f l i g h t conditions i n evacuable a i r c r a f t with e jec t ion seats .

The next l og ica l program should expand t h i s technology base by developing and f l i g h t demonstrating an operationally p rac t i ca l advanced d i g i t a l fly-by- wire control system on a commercial a i r c r a f t . The system should be designed t o function throughout the f l i g h t envelope, from takeoff t o landing, under normal and extreme operating conditions. It should include appropriate redundancy management, automated system t e s t , system control, and system status and advisory displays. Extensive f l i g h t tes t ing must be conducted t o define system performance (compared t o ana ly t ica l predict ions) , r e l i a b i l i t y , f a i l u r e effects , and maintainabili ty requirements under conditions representative of commercial a i r l i n e operation. Realistic design c r i t e r i a and design guide- l i n e s should be developed, based on r e s u l t s of the program, f o r c r i t i ca l and noncr i t ica l control functions. technology recommendations expressed i n the NASA Research and Technology Advisory Council report (Reference 47).

This program should a l s o be responsive t o

A f l i g h t demonstration program formulated t o s a t i s f y these objectives and requirements could bes t achieve credible t e s t r e s u l t s by u t i l i z i n g a current state-of-the-art , operational, commercial a i r c r a f t as the t e s t vehicle. The NASA RSFS airplane i s well qualified a s a t e s t vehicle for demonstrating ce r t a in elements of an advanced control system. This a i r c r a f t i s current ly

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being converted in to a canmercial-type research vehicle under Department of Transportation SST Technology Follow-On Program and NASA Research Support Fl ight System contracts (References 55 and 56). experimental f l i g h t control, navigation, and display equipment being instal led for the RSFS is shown i n the cutaway view of Figure 2. The a i r c r a f t features an a f t f l i g h t deck (AFD) from which a two-man crew may f l y the airplane from takeoff t o landing with controls e l e c t r i c a l l y coupled t o the standard 737 f l i g h t control system. Advanced electronic systems include t r i p l y redundant d i g i t a l automatic f l i g h t control computers and an advanced d i g i t a l navigation, guidance, and display system. A d a t a acquis i t ion system provides experimental data fo r pos t f l igh t analyses. output), which has an electronic fa i l -operat ive capabili ty, is limited t o a single thread actuation capabi l i ty .

Arrangement of the new

The complete system (sensor t o control surface

The current and planned use of the a i r c r a f t is f o r extensive NASA research programs regarding f l i g h t i n the terminal area. The experience obtained during these programs i n the o F r a t i o n and performance of the fai l -operat ional sensor and computer system w i l l be d i r ec t ly applicable t o advanced control system development .

The a i r c r a f t , a s currently configured, has the capabi l i ty t o provide meaningful performance, r e l i a b i l i t y , and maintainabili ty t e s t d a t a i n a limited-cost f l i g h t program. suf f ic ien t system redundancy and capabi l i ty t o more completely model, and thereby provide b e t t e r d a t a on, the performance benefits , r e l i a b i l i t y , and maintainabili ty of these systems. This poss ib i l i t y is being explored by Boeing-Wichita under contract t o NASA-Langley.

The a i r c r a f t could a l so be modified t o provide

Re d und a ne y Management

The redundancy required for a f l i g h t - c r i t i c a l control system depends t o a great extent on the mechanization scheme adopted, as well as the f a i lu re character is t ics of the system under consideration. Similar considerations apply whether the element i s a mechanical actuator or an electronic element. DOT-sponsored research (References 53 and 54) examined the elements of the U. S. SST prototype control system and ident i f ied problem areas associated w i t h the redundancy of those systems, e.g., channel interactions, f a i lu re detection, and f a i lu re e f f ec t s on system performance. A NASA-sponsored study (Reference 27) reviewed ten current actuator redundancy mechanization schemes and ident i f ied two concepts t h a t would meet advanced airplane f l i g h t cont ro l system requirements.

These r e su l t s a r e c i ted as evidence t h a t work is proceeding in t h i s area. ’ But it must be pointed out that since computation and actuation a re key elements of any control system, the promise of advanced controls w i l l not be realized u n t i l the technology f o r providing adequate r e l i a b i l i t y with reasonable system cost i s i n hand. Appropriate research must be carried out i n t h i s area of redundancy management t o ensure that the design capabi l i ty is available when needed.

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Improved Analysis Techniques

p i s t i n g methods cannot provide the technological base for the design of airplane Configurations that rely on a control system for structural design l o a d reduction, f lu t te r envelope expansion, or s tab i l i ty when balanced

i m u m performance. ic, nonlinear, and unsteady aerodynamics; interaction of structural

Reference 47 points out that these

Some of the more fundamental problem areas are:

deformation and control surface deflections w i t h aerodynamic loading; and the dynamics of large flexible structures. problems "have been painfully evident to aeroelasticians for a t least three decades ."

Current analytical capability must be expanded t o provide adequate treatment of these problem areas. Analytical methods for the rapid incor- poration of experimental data into the analyses should be pursued w i t h the objective of successfully treating separated flow regions and nonlinearities due t o discontinuities. verified through correlation with wind tunnel and f l i g h t tes t data. tentative steps are being taken in t h i s direction, but much additional work remains.

The methods resulting frun th i s work should be A f e w

In the past, wind-tunnel testing of dynamically scaled airplane models has proven economically desirable t o predict airplane dynamic characteristics prior t o f l i g h t testing. As aircraf't become more dependent on s tabi l i ty augmentation systems, wind-tunnel testing of aeroelastic models t o prove control concepts w i l l become increasingly more attractive t o increase confidence i n analyses, as discussed in Reference 48. --.

I n 1967, AFFDL and NASA-Langley jo in t ly in i t i a t ed a program to demonstrate an act ive modal suppression system on a one- th i r t ie th scale B-52E aeroe las t ic model i n the Langley transonic dynamics tunnel. This model includes a i le ron and elevator actuat ion systems and provisions f o r a cable mount system (Reference 49). Model gust responses have been obtained using the airstr-am osc i l l a to r system ins ta l led in the tunnel (Reference 50). Boeing-Wichita i s a s s i s t i n g NASA i n developing a r ide smoothing system f o r the model using 50 Hz bandwidth a i l e ron and elevator actuation systems. Subsequently, canards and flaperons were added f o r RC and FMC tes t ing , which is now nearing completion. I n 1974 a MLC system w i l l be tes ted .

I n addition, wind tunnel t e s t s have been conducted a t NASA-Langley on a SST wing model which u t i l i z e s a $PIC system (References 51 and 52). use of such models will be of great benef i t i n CCV system synthesis and test.

Wider

Results of the recent ly completed B-52 CCV program indicate tha t precise mathematical models may not be quite a s v i t a l a s s ta ted above. Inaccuracies i n the math model may be made to le rab le by in t e l l i gen t locat ion of force producers, and use of motion sensors located a t several d i f f e ren t points in the s t ruc ture t o be controlled (Reference 57).

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CONCLUDING REMARKS

Within the past decade a great amount of work has been performed t o demonstrate benef i t s of ac t ive controls technology, yet today applications of t h i s technology are few. The best way t o develop confidence i n these concepts i s t o f l i g h t demonstrate the concepts on a commercial transport under normal and extreme operating conditions. demonstrate and e s t ab l i sh confidence in CCV/ACT technology.

Such a program w i l l c l ea r ly

REFEXENCES

1. Holloway, Richard B., "Introduction of CCV Technology in to Airplane Design." Paper presented a t the AGARD Fl ight Mechanics Panel Symposium on Aircraf t Design Integration and Optimization, Florence, I t a ly , October 1-4, 1973. (Also as Boeing Wichita Division Document D3-9210).

2. Shomber, Henry A., and Holloway, Richard B., "Advanced Controls f o r Commercial Transport Aircraf t . I 1

Meeting, Dallas, Texas, April 30 - May 2, 1974. Presented a t the SAE A i r Transportation

SAE Preprint No. 740453.

3. Tomlinson, L. R., "SST Longitudinal Control System Design and Design Processes, Hardened S t a b i l i t y Augmentation Design." Federal Aviation Administrat ion Report FAA-SS-73-1, June 1973. Commercial Airplane Company Document ~6-60285) . (Also as Boeing

4. Bla t t , Paul E., "Flight Control System Advances fo r Near Future Mili tary Aircraft ." Presented a t SAE Committee A-6 Meeting, San Diego, Calif ., October 24, 1973.

5. Pasley, L. H. and Kass, G. J., "Improved Airplane Performance Through Advanced Flight Control System Design," A I A A Paper No. 70-785, Toronto, Canada, July, 1970.

6. Pasley, L. H., and Wattman, W. J., "Compatibility of Maneuver Load Control and Relaxed S t a t i c S tab i l i ty , AFFDL-TR-71-183. (Abbreviated version a l so published a s A I A A Paper 73-791, August 1973.)

7. Johannes, R. P., and Thompson, G. O., "B-52 Control Configured Vehicles Program," Boeing Document D3-9169. and Control Panel 17th Symposium on Advances i n Control Systems, Geilo, Norway, September 1973.

Presented a t the AGARD Guidance

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Morris, R. L., Hanke, C. R. , Pasley, L. H. and Rohling, W. J., "The Influence of Wing-Loading on Turbofan Powered STOL Transports with and without Externally Blown Flaps - Fina l Report , I t Boeing Document D3-8514-7, 1973 *

Holloway, R. B., Thompson, G. O., and Rohling, W. J., "Prospects f o r Low-Wing-Loading STOL Transports with R i d e Smoothing," Journal of Aircraf t , Volume 9, No. 8, pp. 525-530, August 1972.

White, R. J., "Improving the Airplane Efficiency by U s e of Wing Maneuver Load Alleviation," Journal of Aircraf t , Vol. 8, No. 10, October 1971, page 769.

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34. Goodmanson, L. T. and Gratzer, L. B., "Recent Advances i n Aerodynamics for Transport Aircraf t ," AIAA Paper No. 73-9, Jan. 1973.

35. Hood, R. B., "Active Controls: Changing the Rules of Struc tura l Design," Astronautics and Aeronautics, Aug. 1972.

36 9

37

38

39

40.

41.

42.

43

44.

45

46.

47 *

48.

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672

MARKET IDENTIFICATION CONCEPT DEVELOPMENT

PRELIMINARY DESIGN OFFER FOR SALE

DESIGN AND PRODUCTION OF BA.SIC AIRPLANE

PR& I m A L w

GO-AHEAD DELIVERY 100

80

60

PERCENT

40

20

0 TIME- *

FIGURE 1. COST MANAGEMENT OF A TYPICAL COMMERCIAL PROGRAM

ADVANCED ELECTRONIC

AFD INTERFAC

RECORDERS

LIGHT CONTROL OMPUTER PALLET

FIGURE 2 - RESEARCH SUPPORT FLIGHT SYSTEM - INTEFtNAL ARRANGEMENT

673

TABLE I

CONCEPI

B-52

x8 =io ___-

c -5A

LOCKEIEED WUBLE-DELTA

STOL

LARGE JET

(700,000 LB. I CLAW

i------ I U.S. SST

ADVANCED TECHNOLOGY

~ L-1011

CCV/ACT PERFORl AUGMENTED GUST LOAD STABILITY ALLEVIATION

13.7% G. WT. RE DUCTION

LONGITUDINAL STABILITY. 1

MECHANICAL FLAP LWL DESIGl APPROX. 12% LIGHTER G. WT. THAN EXT'L BLOWN FLAP DE SIGNS. (REF. 29)

SAVINGS. 2.5% CRUISE DRAG REDUCTION

IN LATERAL GUST DESIGN LOADS (REF. 271

LANCE PAY-OFF ST FATIGUE MANEUVER

REDUCTION LOAD CONTROL

SEE REFS. 8-18

5% G.WT. REDUC TION POSSlBLE SEE REFS. 5-6. CCV P R O W M FLIGHT DEMO. 10% REDUCTION IN WING ROOT BENDING DUE TO MANEUVERS. (REF. 57)

SEE REFS. 19-25

MLC PROVIDED 10,000 LB PAY - LOAD INCREASE. (REF. 31)

SEE REFS. 34-35

10% WEIGHT DECREASE, 7% PROFILE DRAG RED'N. (REF. 39)

SEE REFS. 40-42

70.000 LB. 14% G.WT. FIGHTER (BOEING RED% POSSIBLE

MODEL 818) (REF. 6)

APPROX. 10% NEGATIVE STABILITY MARGIN (REF. 44)

YF-16

[DIE s I

FLUTTER R I D E g F 1 MODECONTROL

(FMC)

CCV PROGRAM (REF. 57) FLIGHT DEMO. 30% ACCELERATION REDUCTION AT PILOT'S STATION BOTH VERTICAL & LATERAL. ' 1

CCV PROGRAM (REF. 57) FLIGHT DEMO. 30% EXTENSION IN FLUTTER PLACARD.

SEE REFS. 19-25

50% VERTICAL ACCELERATION REDUCTION. (REF. 28)

VERTICAL ACCEL < . 11 g'S RMS.

S .055 g'S RMS. GTERAL ACCEL.

(REF. 30)

IN GUST -INDUCED LATERAL ACCELERATION I N 747 AFT J3ODY (REFS 2 & 58)

SEE REF. 33 SEE REF. 33

78% REDUCTION IN CREW STATION ACCELERATION. SEE REFS. 36 - 38

SEE REPS. 40-42

POSSIBLE. (REF. 6)

150 KT. FLIGHT ENVELOPE EX PANSION (REF. 43)

674