Research Memorandum

RESEARCH MEMORANDUM

EFFECT OF SEVERAL WING MODIFICATIONS ON THE-

LOW-SPEED STALLING CHARACTERISTICS OF THE

DOUGLAS D-558 -II RESEARCH AIRPLANE

By Jack Fischel and Donald Reisert

High-Speed Flight Station Edwards, Calif. 8$ t!Y@g* g*&:$ Qs? vi? &&. &i * CIASSWIEDDCCUMENT O( ThismaterialcontaiisfnfmmaticmdfO@lngtimNationalEefenseof b UrdtadSt8teswfthfntb me4?@g oftheespionagelaws,Title18,U.S.C.,Sec.%‘/S9and794,b trmmmlaslmorrav8Mioaof whichinw ~ mnnwrto amun.autlmizedpersonlsprohibitedtq law. NATIONAL ADVISORY COMMITTE~ FOR AERONAUTICS NACA RM H~~E31a CONFIDENTIAL

NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

RESEARCH MEMORANDUM

EFFECT OF SEVERAL WING MODIFICATIONSON THE

LOW-SPEED STALLING CHARACTERISTICSOF THE

DOUGLAS D-558-II RESEARCH AIRPLANE

By Jack Fischel and Donald Reisert

The low-speed stalling and lift characteristicsof the Douglas D-558-II airplane were measured in a series of lg stall approaches performed with several wing modificationsdesigned to alleviate swept-wing instabilityand pitch-up. The airplane configurationsinvestigated include the basic wing configurationand two wing-fence configurations in combinationwith retracted, free-floating,or extended slats, and a wing leading-edgechord-extensionconfiguration. All configurations were investigatedwith flaps and landing gear retracted and extended at an altitude of about 20,000 feet.

With slats, flaps, and landing gear retracted, none of the wing modifications investigatedhad an appreciableeffect on the lift or stability characteristicsat low and moderate angles of attack. Regardless of wing-fence configuration,appreciably larger values of peak normal- force coefficientwere attained with slats unlocked (free floating) or fully extended than with slats closed. Wing fences and the chord- extension tended to delay the onset of instabilitywith slats retracted, and the stable region was further extended for the configurationswith either no wing fences or inboard wing fences when the slats were free floating or extended.

With flaps and landing gear extended, only the fully extended slat configurationaffected the variation of normal-force coefficientwith angle of attack by increasing this variation slightly. Peak values of normal-force coefficientattained were the same for all configurations except the chord-extensionconfiguration. For this configurationexces- sive buffeting caused earlier termination of the maneuver. Most of the configurationshad little or no effect on the stability characteristics over most of the lower and moderate angle-of-attackrange. The airplane appeared somewhat more stable, however, with no wing fences installed than with wing fences installedwhen the slats were extended. At larger angles of attack and with slats extended, inboard wing fences materially improved the stability characteristicsof the airplane. CONFIDENTIAL 2 CONFIDENTIAL NACA RM H55E31a

At any given angle of attack, wing flaps provided an increment in normal-force coefficient of about 0.3; whereas, the free-floatingor fully extended slats provided zero incrementallift except at very large angles of attack. The airplane generally appeared more stable longi- tudinally at comparable speeds with flaps deflected than with flaps retracted,but marginal dynamic lateral stabilitywas evident for several configurationswith flaps extended or retracted.

In general, adequate stall warning in the form of buffeting was noted by the pilot in the stable region of flight, particularly for the chord-extensionconfigurationfor which buffeting appeared aggravated.

INTRODUCTION

As a part of the cooperativeAir Force— Navy-NACA high-speed flight program, the National Advisorv Committee for Aeronautics is conducting a fliszht-researchprogram utili~ing the Douglas D-558-II swept-wing research airplane. During tie course of ~his flight program, the effects of various modificationsdesigned to alleviate swept-wing instabilityand pitch- up were investigatedfrom stalling speed up to a maximum Mach number of about 1.0 (refs. 1 to 3). The airplane configurationsinvestigated include the basic wing configurationand two wing-fence configurations in combinationwith retracted, free-floating,or extended slats, and a wing leading-edgechord-extensionconfiguration. The results of the low- speed stalling characteristicsof the airplane in each of the aforemen- tioned configurations,with flaps and landing gear retracted and extended, are presented in this paper.

SYMBOIS b wing span, ft

CNA airplane normal-forcecoefficient, nW/qS

wing chord, ft

wing mean aerodynamic chord (M.A.C.), ft

Fa aileron control force, lb

Fe elevator control force, lb

Fr rudder control force, lb CONFIDENTIAL RM H55E31a CONFIDENTIAL

accelerationdue to gravity, ft/sec2

pressure altitude, ft

stabilizer setting with respect to fuselage center line, positive when leading edge of stabilizer is up, deg

free-streamMach nuniber

normal load factor”or acceleration,g units

free-streamdynamic pressure, lb/sq ft

wing area, sq ft

time, sec

indicated airspeed, mph

airplane weight, lb

angle of attack of airplane center line, deg

angle of sideslip, deg

total aileron position, deg

elevator position with respect to stabilizer,deg

rudder position with respect to vertical tail, deg

slat position, in.

pitching velocity, radians/see

rolling velocity, radians/see

yawing velocity, radians/see

AIRIZANE

The Douglas D-558-II airplane used in this investigationis equipped with both a Westinghouse J34-WE-40 turbojet engine, which exhausts out the bottom of the fuselagebetween the wing and the tail, and a Reaction

CONFIDENTIAL 4 CONFIDENTIAL NACA RM H55E31a

Motors, Inc. LR8-RM-6 rocket engine, which exhausts out the rear of the fuselage. The airplane is air-launchedfrom a Boeing B-29 mother airplane. A photograph of the airplane is shown in figure 1 and a three- view drawing is shown in figure 2. Pertinent dimensions and characteristics of the unmodified airplane are listed in table I.

For the present series of tests several wing-fence configurations were investigatedin combinationwith several slat configurations. A wing leading-edgechord-extensionwas also investigated. The fence configurationsare shown in figures 3 and 4. ‘The inboard wing fences were incorporatedin the original airplane configurationto improve the longitudinal stability characteristicsof the airplane at low speeds and at high an les of attack (a > 10°) when the wing slats were fully extended (ref. 4.T The outboard wing fences were similar to the optimum fence configurationdeveloped in the wind-tunnel investigationof reference 4 for improving the longitudinalstability characteristicsat high angles of attack in the airplane clean condition. The wing slats (figs. 5 and 6) may be locked in either the open (extended)or closed (retracted) position, or they may be unlocked (free floating). In the unlocked Con- dition they are normally closed at low values of angle of attack or normal-force coefficientand open with increase in angle of attack. The left and right wing slats are interconnectedand always have approximately the same position.

The wing leading-edgechord-extensionsshown in figures 7 and 8 were similar to those tested in the wind tunnel and found to provide an improvement in static longitudinalstability at moderate angles of attack (refs. 5, 6, and unpublished data). ~ese chord-extensionswere approximatelythe NACA 63-008airfoil profile in the streamwise direc- tion and were faired into the wing profile over the span of the chord- extensions. In addition, the chord-extensionswere faired into the wing tips and the inboard ends were flat-sided in the vertical streamwise plane. For this configurationthe wing slats were locked closed and all fences were removed. Addition of the wing chord-extensionsincreased the wing area from 175 square feet to 181.2 square feet and the wing mean aerodynamic chord from 87.3 inches to 90.0 inches. For convenience in comparisonof the data with data for the unmodified airplane, however, all data presented are based on the dimensions of the unmodified airplane.

The airplane is equipped with an adjustable stabilizerbut there are no means provided for trimming out aileron- or rudder-controlforces. No aerodynamicbalance or control-forceboost system is used on any of the controls. Hydraulic dampers are installed on all control surfaces to aid in the prevention of control-surface“buzz.” Dive brakes are located on the rear portion of the fuselage.

Figure 9 shows the friction in the elevator-controlsystem as measured on the ground under no load as the control was deflected slowly.

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 5

The rate of control deflectionwas sufficientlylow so that the control force resulting from the hydraulic damper in the control system was negligible.

INSTRUMENTATION

Among the standard NACA recording instrumentsinstalled in the airplane to obtain flight data were instrumentswhich measured the following quantitiespertinent to this investigation:

Airspeed Altitude Angle of attack Angle of sideslip Normal acceleration Rolling, yawing, and pitching velocities Stabilizer,elevator, aileron, rudder, and slat positions Aileron and elevator wheel force Rudder pedal force

All instrumentswere synchronizedby means of a common timer.

The elevator and rudder positions were measured at the inboard end of each control surface; the left and right aileron positions were measured on bell cranks about 1 foot forward of the ailerons; and the stabilizer position was measured at the plane of symmetry. All control positions were measured perpendicular to the control hinge line.

An NACA high-speed pitot-static tube (type A-6 of ref. 7) was mounted on a boom &feet forward of the nose of the airplane. The vanes used to measure the angle of attack and angle of sideslip were mounted on the same boom about ~ feet and 3 feet, respectively, forward of the nose of the airplane. Angle of attack and angle of sideslip are presented as measured with only instrument correctionsapplied. However, any inherent errors, such as caused by upwash effects, are believed to have a negligible effect on the analysis of the data.

TESTS

The”low-speed stalling and lift characteristicsof the Douglas D-558-II airplane were measured in a series of lgstall approaches in the following airplane configurations: .

CONFIDENTIAL CONFIDENTIAL NACA RM H55E31a

1. Basic wing configuration (no fences).

(a) Slats retracted (locked closed), flaps and landing gear retracted. (b) Slats unlocked, flaps and landing gear retracted. (c) Slats unlocked, flaps and landing gear extended.

2. Inboard wing fences.

(a) Slats retracted, flaps and landing gear retracted. (b) Slats unlocked, flaps and landing gear retracted. (c) Slats unlocked, flaps and landing gear extended.

3. Inboard and outboard wing fences.

(a) Slats retracted, flaps and landing gear retracted. (b) Slats unlocked, flaps and landing gear extended.

4. Wing slats fully extended (no wing fences).

(a) Flaps and landing gear retracted. (b) Fkps and landing gear extended.

5. Wing slats fully extended and inboard wing fences.

(a) Flaps and landing gear retracted. (b) Flaps and landing gear extended.

6. Wing leading-edgechord-extensions(no fences, slats retracted).

(a) Flaps and landing gear retracted. (b) Flaps and landing gear extended.

The stall approacheswere performed at altitudes between about 18,700 feet and 21,’jOOfeet and at a generally constant wing loading of 64 pounds per square foot. The location of the airplariecenter of gravity was between 24.9- and 26.9-percentmean aerodynamic chord for all but the chord-extensionconfiguration. For the chord-extension configurationthe center of gravity was located between 22.4- and 22.8-percentmean aerodynamic chord in order to provide the same degree of apparent longitudinalstability for the airplane as in the unmodified configurationwith the center of gravity at about 25- to 26-percent me~ aerodynamic chord (refs. 3 and 5). Stabilizer control settings ranging from 1.3° to 2.3° were used for all the maneuvers.

In general, the stall-approachmaneuvers were performed at a rate of decreasing airspeed of about 1 to 2 miles per hour per second. The pilots attempted to continue the maneuver to as low a speed as feasible, but usually terminated the maneuver after pitch-up or severe roll-off

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 7 was experienced and subsequentlyeffected recovery. As a result, the complete wing stall or maximum normal-forcecoefficientgenerally was not realized in the maneuvers.

RESULTS AND DISCUSSION

Data obtained during the stall-approachmaneuvers performed in each configurationare presented in figures 10 to 23 in the form of time- histo~ plots and as the variation of several pertinent longitudinal stability quntities with indicated airspeed. Inasmuch as almost similar wing loadings and test altitudes existed for all maneuvers, indicated airspeed has been used as a variable to show and compare stability characteristicsfor the various configurations. For convenience in com- paring the data, the flight conditions and figure numbers of the data presented are tabulated in table II. Figures 24 to 27 present comparison plots showing the effect of wing modificationon the variation of elevator deflection and normal-force coefficientwith angle of attack for each configurationinvestigated.

Because of the similarity in several of the characteristicsexhibited by the airplane during the stall approaches,regardless of wing configuration, a rather complete discussion of the data obtained is confined to the basic wing configuration. Only those characteristicspertinent to each of the other configurationsare discussed in this paper. For convenience in presentation,a summary of results obtained during the reported maneuvers is presented in table III.

Effect of Wing Configurationon Stalling and

Lift Characteristics

Basic wing configuration.- Measured data obtained during lg stall approaches performed in each of three conditionswith the basic wing configurationare shown in figures 10 to 12. In the clean condition the poor lateral damping characteristicsof the airplane for small- amplitude oscillations (ref. 8) are observed at Vi > 195 mph; however, below 195 mph the lateral stability improves. Lateral stability again deterioratesat speeds below approximately190 mph, with accompanying erratic motion in both the aileron and elevator controls (fig. 10(a)). As a result of the erratic control motion and poor airplane response at lower speeds shown in figure 10(a), the variation of the quantities plotted against Vi in figure 10(b) shows appreciable scatter. How- ever, general trends may be noted from these plots. The apparent stick- fixed longitudinalstability, indicatedby the slope of the curve of elevator deflection against Vi, appears to be positive as speed is

CONFIDENTIAL 8 CONFIDENTIAL NACA RM H~5E31a decreased to Vi = 185 mph, is approximatelyneutral to Vi = 170 mph, and appears unstable at speeds below Vi ~ 170 mph. ‘In figure 10(a) a large amount of down-elevatorcontrol application is apparent from time 102.0 seconds to 104.3 seconds, after which up-elevator control application is again apparent. This trend results from the apparent pitch-up experiencedby the pilot, who applied excessive elevator-controldeflec- tions in an attempt to control the airplane, thereby causing the airplane to pitch down and then up. Subsequent to this experience the maneuver was terminated. The push-down performed by the pilot usually accentuated the stick-fixed instabilityof the airplane at low speeds. (This general trend was experiencedand followedby the pilots during most of the maneuvers, as may be noted in the data presented herein.) In general, the apparent stick-free longitudinalstability, indicated by the slope of the curve of Fe against Vi, appears neutral over most of the stall-approachmaneuver and much of the elevator-forcevariation lies within the control-frictionband (fig. 9). peak values of a= 14° and CNA = 0.95, correspondingto a minimum speed of Vi = 168 mph, were obtained in this maneuver.

With the slats unlocked appreciableaileron control movement was required as the stall was approached,but the airplane motions appear relatively smooth (fig. 11). The opening of the slat appears gradual and smooth and the airplane appears to retain apparent stick-fixedlon- gitudinal stability down to Vi ~ 175 mph. Opening the slat had no effect on the speed at which the airplane became unstable (Vi * 170 mph); however, higher peak values of a and CNA and a lower minimum speed were realized with the slats unlocked. The apparent stick-free longitudinal stability appeared neutral over most of the stall-approach maneuver and unstable at speeds below Vi x 178 mph.

Extending the flaps and landing gear with the slats unlocked increased the degree of apparent stick-fixedand stick-free longitudinal stability at comparable airspeeds and appreciablydecreased the minimum speed and increased the peak values of u and CNA attained (fig. 12). Stick-fixed instabilityIs apparent at speeds below Vi s 144 mph. Stick- free instabilityis apparent at speeds below Vi = 147 mph. In general, the slat opening was smooth and gradual and, as the stall was approached, the control motions and airplane response appear smoother than in the other two flight conditionsdiscussed. At Vi > 18o mph, however, a Dutch roll type of oscillationwas experiencedand is shown in the data of figure 12(a). In addition some evidence of right-wing heaviness, resulting from extending the flaps and landing gear, is shown by a comparison 0$ the ba data of figures 10(a), n(a), and 12(a).

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 9

Unlocking the slats with gear and flaps retracted produced no increment of CNA for given values of a; however, extending the flaps and . gear produced an increment in CNA of about 0.3.

Pilots’ descriptionsof the stall-approachmaneuvers in the subject configurationare in general agreementwith the preceding discussion. In addition, the pilots detected the onset of mild buffet at vi = 190 mph in stalls performed with flaps and gear retracted, and at vi = 170 mph with the flaps and gear extended and slats unlocked.

Configuration with inboard wing fences.- Data obtained during lg stall approachesperformed with inboard wing fences installed are presented in figures 13 to 15. A more complete discussion of stall-approach maneuvers performed in this configurationwith another D-’558-IIairplane is presented in reference 9.

Adding the inboard wing fences caused a slight improvement in the dynamic lateral stability characteristicsof the airplane in the clean condition and made possible considerablysteadier flight. In addition the airplane tended to retain some degree of apparent stick-fixedlon- gitudinal stability to lower airspeeds with inboard fences than was maintained in the basic win configuration. (Comparedata of figs. 10 and 13; also see table III.7 However, with the addition of the wing fences, wing dropping was experiencednear the stall as evidenced by the left aileron input starting at time 12 seconds (fig. 13(a)) and as reported by the pilot.

Unlocking the slats had a small effect toward increasingthe degree of stick-fixed stability exhibited by the airplane in the stall approach and lowered the speed below which the airplane became stick-fixed unstable to Vi s 161mph (fig. 14). The latter effect is in agreement with the results of the wind-tunnel investigationof reference 4 and was also reported in greater detail in reference 9. Also, as previously discussed for the basic wing configuration,the pilot reported that unlocking the slats resulted in a smoother stall-approachmaneuver in this configurationthan with slats locked closed. As a result of the improved stalling characteristics,a lower minimum speed and higher peak values of a and CNA were attained in this maneuver than were obtained with the basic wing configuration.

With the slats unlocked and flaps and landing gear extended, a Dutch roll oscillationwas experienced at the higher stall-approach speeds. Erratic control motions and airplane response were exhibited at the lower speeds and the airplane motion and elevator input appeared 18oo out of phase prior to the stall (fig. 15(a)). me degree of apparent stick-fixed stabilitywas approximatelythe same with the slats

CONFIDENTIAL 10 CONFIDENTIAL NACA RM H55E31a unlocked and flaps and gear retracted or extended at comparably low and moderate values of a, but at comparable speeds appeared to be greater with flaps and gear extended. In other respects the airplane exhibited roughly the same characteristicsas in the basic wing configuration. Buffet warning was reported by the pilot at Vi ~ 155 mph which is well above the stall speed. The pilot also reported the lateral stabilitywas marginal below about 16o mph.

Configuration with inboard and outboard wing fences.- Data obtained during lg stall-approachmaneuvers performed in the configurationincor- porating two fences in the clean and landing conditions are shown in figures 16 and 17.

For the clean-conditionstall approach a small degree of apparent stick-fixed longitudinalstability is exhibited at speeds down to Vi % 175 mph. Below Vi s 175 mph the static longitudinalstability appeared to decrease and the pilot experienceddifficulty in flying the airplane smoothly. These effects may be noted in figure 16, particularly the erratic airplane and control motions as the stall was approached.

Extending the flaps and gear and unlocking the slats resulted in an increase in the apparent stick-fixedlongitudinalstability at comparable speeds (fig. 17). In general, the stick-free stability was neutral at speeds above Vi ~ 145 mph. Below vi = 145 mph the apparent stick-free and stick-fixedstability appeared to decrease. Evalua- tion of this condition,however, is difficult because of the erratic airplane and control motions in this speed range. Slat opening appears fairly gradual and smooth and pilot observationof buffet was reported at Vi = 143 mph, which is fairly close to the minimum speed of 131 mph indicated for this maneuver.

In general this configuration,as did the previous configuration, provided only a small improvementin handling characteristicscompared with the characteristicsof the basic wing configuration.

Configurationwith slats fully extended (no wing fences).- Stall- approach data obtained with the slats in the fully extended position (fig. 5) and with no wing fences installedare shown in figures 18 and 19 for the conditionswith flaps and gear retracted and extended, respectively.

In either condition, the data show the control motions and airplane motions to be erratic as the minimum speed of each maneuver was approached. A comparison of the data of figures 18 and 19 and table III shows that the airplane exhibited a greater degree of apparent stick-fixed stability in the landing condition and retained stability down to appreciably lower speeds than when the flaps and gear were retracted. In both conditions the stick-free characteristicsappear marginal over most of the speed

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 11 range and unstable at the lower speeds. With flaps and gear retracted the pilot reported roll-off tendenciesnear minimum speed. With flaps and gear extended, marginal dynamic lateral stabilitywas reported at speeds below Vi = 150 mph and the data of figure 19(a) indicate a left-wing heaviness as the speed decreased.

With the slats fully extended the airplane attained appreciably higher values of a and CNA and a lower minimum speed than in the basic wing configurationwhen the flaps and gear were retracted. These margins were not so markedj howeverj in the landing condition. In most other respects these two configurationsappeared similar.

Configurationwith slats fully extended and inboard wing fences.- Data obtained during the lg stall-approachmaneuvers with slats fully extended and inboard fences at 0.36 wing semispan are shown in figure 20 for the conditionwith flaps and gear retracted and in figure 21 for the landing condition.

The control motions and airplane response appear only slightly erratic with flaps and landing gear retracted (fig. 20(a)); however, this effect is mainly in the lateral plane. Appreciable use of aileron and rudder is noted in the time-historyplot for the landing condition (fig. 21(a)), but the airplane motions do not appear severe until the stall is approached. With flaps and gear retracted, the airplane is shown to be slightly stable longitudinallyto Vi x 167 mph as speed is reduced, neutrally stable to 16o mph, and apparentlyunstable at lower speeds. With flaps and gear extended the degree of apparent stability exhibited at comparable speeds or angles of attack was generally greater than with flaps and gear retracted. Also in the landing condition the airplane retained stability to the lowest speed attained (Vi = 127 mph), although a marginal region is apparent from Vi = 145 mph to 135 mph. Adequate stall warning in the form of buffet became more apparent as the stall was approached in either flight condition.

Because of the retention of apparent stick-fixed stability to lower speeds in the landing condition and the absence of any pitch-up, this configurationwas consideredby the pilots to be an improvementover the basic wing configurationat the lower speeds. Table III also shows that this configurationgenerally provided some increase in peak a and CNA and a decrease in minimum Vi attained.

Wing leading-edge chord-extensionconfiguration.-Data obtained during lg stall-approachmaneuvers performed in the clean and landing conditionswith wing leading-edgechord-extensionsinstalled over the outer 0.32 semispan of each wing panel are presented in figures 22 and 23, respectively.

CONFIDENTIAL 12 CONFIDENTIAL NACA RM H55E31a

Inspection of the data of figure 22 shows that the stall performed in the clean condition was generally smooth, with rolling oscillations occurring at speeds below Vi z 185 mph as the stall was approached. The apparent stick-fixed stabilitywas generally stable down to Vi = 197 mph, neutrally stable between Vi x 197 mph and 170 mph, and unstable below Vi = 170 mph. The stick-free stabilitywas generally neutral at speeds above 175 mph and unstable at lower speeds. In the landing condition a slight rolling oscillationwas apparent during the entire maneuver and became more severe near minimum speeds(fig. 23(a)). At Vi < 200 mph the apparent stick-fixedstabilitywas appreciably greater in the landing condition than in the clean condition and positive stabilitywas retained to the minimum speed of the maneuver in the landing condition. However, the pilot reported some tendency toward longitudinaland lateral instability in the landing condition at minimum speed, and the data of figure 23(a) indicate this trend. Also, the stick-free stability in the landing c~nditionwas greater than in the clean condition (comparefigs. 23(a) and 22(a)). The peak values of a ~d CNA attained in the landing conditionwere not appreciablyhigher than in the clean condition, as had been experienced in other configurations investigated,but the incrementaleffect on CNA values over the a range was the same as experiencedwith other configurations. These effects resulted from the fact that the slats were retracted for this configuration,hence wing-flow separationprobably tended to occur at a lower value of a when the flaps were extended. AIso, the pilot noted the start of buffeting at slightly lower values of a and CNA for this configurationthan for other configurationstested and the buffet intensity rise appeared more severe at given values of a and CNA. Therefore, the maneuver in the landing conditionwas terminated at a lower level of a.

Comparison of Stalling and Lift Characteristics

With Various Wing Modifications

Flaps and landing gear retracted.-The effect of the various wing stall-controldevices on the stability and lift characteristicsof the Douglas D-558-II airplane in the clean condition is shown in figure 24. Addition of wing fences or the chord-extensionto the wing panels had little or no effect on the variation of normal-force coefficientwith angle of attack, except for a slight decrease in the slope at a > 12° for the one-fence and chord-extensionconfigurations. Also, the values of peak normal-forcecoefficientattained were about the same for the configurationscompared in figure 24. An appreciabledifference in the apparent stability characteristics,as determinedby the slope of the curve of be plotted against u, is exhibited for the configurations

CONFIDENTIAL NACA RM H55E31a CONJ?IDEN!KCAL 13 discussed. The basic wing configurationexhibits about the same degree of apparent stabilityup to u ~ 10o as exhibitedby the two-fence and chord-extensionconfigurationsup to U=go. This degree of stability is greater than for the one-fence configuration. However, the basic wing configurationappears unstable at a ~ 12°, whereas the other configurations appear unstable at a~ 130.

The effects on the airplane stability and lift characteristicsof unlocking the slats so they were free to float, and of locking the slats in the fully extended position, are shown in figure 25 for the condition of flaps and gear retracted. The slats had little or no effect on the slopes of the curves of normal-force coefficientplotted against angle of attack, regardless of the wing-fence configuration. The peak values - of CNA attained were appreciably larger when the slats were free floating and to a greater degree when the slats were fully extended. These higher values of peak CNA result from the effectivenessof the slats in delaying separationand extending the stable region of the airplane to lower speeds and to higher angles of attack. Comparison of the curves of be plotted against a in figure 25 indicates that the free- floating slats and the fully extended slats generally had an inconsistent or negligible effect on the degree of stability exhibited in the stable region, but extended the peak angle for the positive stability range from u ~ 10o (with slats retracted) to u s 120 for the basic wing airplane, and from a * 130 to a = 150 for the inboard wing-fence configuration. Regardless of slat configuration,the data show the airplane becomes unstable at a greater value of a when the inboard wing fence is installed. These results are in general agreement with those shown in the wind-tunnel investigationof reference 4 for the effects of wing fences and slats on stability. It is noteworthy that the position of the free-floatingslats above a x 130 was similar to the fully extended slat position (figs. 11 and 14), therefore the airplane exhibited generally similar characteristicsat the higher values of a when the slats were free floating or fully extended.

Flaps and landing gear extended.-With the flaps and gear extended, addition of wing fences with the slats unlocked or addition of wing chord-extensions(slats retracted) had a negligible effect on the variation of CNA with a, except for a decrease in slope exhibited at u > 120 for the inboard-fenceconfiguration (fig. 26). Peak values of CNA attained with the basic wing configurationand with both wing- fence configurationswere approximatelythe same. The appreciably lower peak value of CNA for the chord-extensionconfigurationprobably results from the fact that the wing slats were retracted for this configuration and earlier and more severe buffeting was detected by the pilot who terminated the maneuver at a lower value of u and CNA than for the other configurationstested. The degree of apparent stability exhibited by the

CONITCDENTIAL 14 CONFIDENTIAL NACA RM H55E31a four configurationscompared in figure 26 does not differ appreciably at the more moderate values of u, except possibly for the slightly greater apparent stability exhibited by the chord-extensionconfiguration. At angles of attack above about 10° or 12° all configurationsshow a neutrally stable region for several degrees, followed by an unstable region for the basic wing configurationand both fence configurations. Because of the approximatelyneutrally stable region apparent at the higher values of u, appreciable elevator-controlmovements were mde by the pilot during some stall maneuvers with some erratic response from the airplane, resulting in the scatter in data points shown in figure 26.

Inasmuch as lg stall-approachmaneuvers were not performed with the slats retracted and flaps and gear extended, a comparison of only the effects of the free-floatingslat and the fully extended slat on airplane lift and stability characteristicsin the landing condition is feasible. A comparison of data for these configurationsis shown in figure 27 for both the basic wing and inboard-fenceconfigurations. A slight increase in the normal-force-coefficientslope at the lower values of a for both extended-slatconfigurationsis apparent compared with the data for the free-floatingslat configurations. At the higher angles of attack, however, the variation of CNA with a is greater for the inboard-fence configurationwhen the slats are fully extended, and is greater for the basic wing configurationwhen the slats are free floating (unlocked). The reasons for these differencesare not readily apparent, especially since the free-floatingslats are essentially “fully extended” at angles of attack above about 12° (figs. 12(a) and 15(a)). Slat configuration appeared to have only a small effect on the apparent stability characteristics at us 12° for either wing-fence condition;however, it will be noted that the airplane appeared somewhat more stable with no wing fences than with the inboard fences when the slats were fully extended. At ~ ~ & the main effect noted is the unstable trend shown for the basic wing slats-extendedconfigurationas compared to the generally neutrally stable or slightly stable regions shown by the other configurations. This effect is in agreement with the results shown in reference 4 for the effects of adding similar inboard wing fences to the extended-slat airplane configuration.

In general, the pilots considered the configurationembodying extended wing slats and inboard wing fences the most satisfactoryfor performing stall-approachmaneuvers.

CONCLUDING REMARKS

The low-speed stalling and lift characteristicsof the Douglas D-558-II airplane were measured in a series of lg stall-approachmaneuvers

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 15 performed with several wing modificationsdesigned to alleviate swept- wing instabilityand pitch-up. The various airplane configurations investigatedinclude a basic wing configurationand two wing-fence configurations in combinationwith retracted, free-floating,or extended slats, and a wing leading-edgechord-extensionconfiguration. All configurationswere investigatedwith flaps and landing gear retracted and extended.

With slats, flaps, and landing gear retracted, none of the wing modifications investigatedhad an appreciableeffect on the lift or stability characteristicsat low and moderate angles of attack. Regard- less of wing-fence configuration,appreciably larger values of peak normal-forcecoefficientwere attained with slats unlocked (free floating) or fully extended than with slats closed. Wing fences and the chord- extension tended to delay the onset of instabilitywith slats retracted, and the stable region was further extended for the configurationswith either no wing fences or inboardwing fences when the slats were free floating or extended.

With flaps and landing gear extended, only the fully extended slat configurationaffected the variation of normal-forcecoefficientwith angle of attack by increasing this variation slightly. Peak values of normal-forcecoefficient attainedwere the same for all configurations except the chord-extensionconfigurationfor which excessive buffeting caused earlier termination of the maneuver. Most of the configurations had little or no effect on the stability characteristicsover most of the lower and moderate angle-of-attackrange. The airplane appeared somewhat more stable, however, with no wing fences installed than with wing fences installedwhen the slats were extended. At larger angles of attack and with slats extended, inboard wing fences materially improved the stability characteristicsof the airplane.

At any given angle of attack, extending the flaps provided an increment in normal-force coefficientof about 0.3; whereas, except for the larger angles of attack, the free-floatingor fully extended slats provided no incrementallift. The airplane generally appeared more stable longitudinallyat comparable speeds with the flaps deflected than with flaps retracted; however, marginal dynamic lateral stability was evident for several configurationswith the flaps extended or retracted.

In general, adequate stall warning in the form of buffeting was noted by the pilot well above minimum speed and in the stable flight

CONFIDENTIAL 16 CONFIDENTIAL NACA RM H55E31a region of the airplane, particularly for the chord-extensionconfigura- ti& for which b~feting appeared aggravated.

High-Speed Flight Station, National Advisory Committee for Aeronautics, Edwards, Calif., May 18, 1955.

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 17

REFERENCES

1. Fischel, Jack, and Nugent, Jack: Flight Determinationof the Longi- tudinal Stability in Accelerated lkneuvers at Transonic Speeds for the Douglas D-558-II Research Airplane Including the Effects of an Outboard Wing Fence. NACA RM L53A16, 1953.

2. Fischel, Jack: Effect of Wing Slats and Inboard Wing Fences on the Longitudinal Stability Characteristicsof the Douglas D-558-II Research Airplane in Accelerated Maneuvers at Subsonic and Transonic Speeds. NACA RM L53L16, 1954.

3. Fischel, Jack, and Brunn, Cyril D.: Longitudinal Stability Character- istics in Accelerated Maneuvers at Subsonic and Transonic Speeds of the Douglas D-558-II Research Airplane Equipped With a Leading-Edge Wing Chord-Extension. NACA RM H541KL6, 1954.

4. Queijo, M. J., and Jaquet, Byron M.: Wind-Tunnel Investigationof the Effect of Chordwise Fences on Longitudinal Stability Characteristics of an Airplane Model With a 35° Sweptback Wing. NACA RM L50K07, 1950.

5. Jaquet, Byron M.: Effects of Chord Discontinuitiesand Chordwise Fences on Low-Speed Static tingitudinal Stability of an Airplane Model Having a 35° SweptbackWing. NACA RM L52C25, 1952.

6. Jaquet, Byron M.: Effects of Chord-Extensionand Droop of Combined Leading-Edge Flap and Chord-Extensionon Low-Speed Static Longi- tudinal Stability Characteristicsof an Airplane Model Having a 35° Sweptback Wing With Plain Flaps Neutral or Deflected. NACA RM L52K21a, 1953.

7. Gracey, William, Letko, William, and Russell, Walter R.: Wind-Tunnel Investigationof a Number of Total-PressureTubes at High Angles of Attack - Subsonic Speeds. NACA TN 2331, 1951. (Supersedes NACA RM L50G19.)

8. Stillwell,W. H., and Wilmerding, J. V.: Flight MeasurementsWith the Douglas D-558-II (BuAeroNo. 37974) Research Airplane - Dynamic Lateral Stability. NACA RM L51C23, 1951.

9. Stillwell,W. H., Wilmerding, J. V., and Champine, R. A. : Flight MeasurementsWith the Douglas D-558-II (BuAeroNo. 37974) Research Airplane - Low-Speed Stalling and Lift Characteristics. NACA RM L5OG1O, 1950. 18 coNFIDmIAL NACA RM ~5E31a

TASLEI.- PHYSICAL CHARACTERISTICS OF TEE UNMODIFIED DOUX.AS D-558-II AIRPIANE

Wing: R;ot airfoil section (normal to 0.30 chord Of unswept panel) ...... NACA63-010 Tip airfoil section (normal to 0.30 chord of unswept panel) ...... NACA631-012 Totalarea, sqft...... 175.0 Span,ft ...... 25.0 Mean aercdynamlcchord, in...... 87.301 Root chord (parallel to plane of symmetry), in...... 108.51 Tip chord (parallel to plane of symmetry), in...... 61.18 Taper ratio...... 0.%5 Aapectratio ...... 3.570 Sweep at 0.30 chord of unswept panel, deg ...... 35.0 Sweep ofleadingedge, deg ...... 38.8 Incidence at fuselage center line, deg ...... Dihedral, deg...... -;:: Geometric twist, deg ...... Total aileron area (reemnard of hinge line), sq ft ...... 9.; Aileron travel (each), deg ...... *15 Total flaparea, sqft ...... 12.38 Flaptravel, deg ...... 50

Horizontal tail: Root airfoil section (normal to 0.30 chord of unswept panel) ...... NACA 63-010 TiDairfoil section (normal to 0.30 chord of unswemt DEUE1) ...... NACA 63-01.o Ar&a (including fuaeiage), sqft ‘...... ; .-...... ‘39.9 Span, in...... 143.6 Meanaero_c chord, in...... 41.75 Root chord (parallel to plane of synrm?try),In...... 53.6 Tip chord (parallel to plane of synnnetry),in...... 26.8 Taperratlo...... 0.50 Aspect ratio ...... 3.59 Sweep at 0.30 chord line of unswept panel, deg ...... 40.0 Dihedral, deg...... Elevatorarea, sqft ...... 9.: Elevator travel, deg m ...... 25 Down” : ...... 15 Stabilizer travel, deg Leadingedgeup...... 4 Leadlngedgedown...... 5

Vertical tail: Airfoil section (normal to 0.30 chord of unswept panel) ...... NACA 63-010 Area, sqft ...... 36.6 Height from fuselage center llne, in...... 98.0 Root chord (parallel to fuselage center line), in...... 146.0 Tip chord (parallel to fuselage center line), In...... Sweep angle at 0.30 chord of unswept panel, deg ...... & Rudder area (rearward of hinge line), sqft ...... 6.15 Ruddertravel, deg ...... ●25

Fuselage: Length,ft ...... 42.o Maxlmumdlaneter, in...... 60.0 Fineness ratio ...... 8.4o Speed-retarder area, sqft ...... 5.25

Engines: Turbojet ...... J34-UE-40 Rocket ...... 1.R8-Fu.l-6

Airplane weight, lb: Nljetand rocket fuel ...... 15,570 Fulljetfuel...... x, 382 No fuel...... 10,822

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 19

. coNFIDmIAL TABLE II.- INDEX TO DATA FIGURES - Concluded

(b) Comparisondata of lift and stability characteristics

Airplane configuration Slat configuration Flaps and landing gear Figure number

Basic wing (no fences) Retracted Retracted 24 Inboard wing fences Retracted Retracted 24 Inboard and outboard wing Retracted Retracted 24 fences Wing leading-edgechord- Retracted Retracted 24 extensions

Retracted Retracted 25 Basic wing (no fences) Unlocked Retracted 25 Extended Retracted 25 Retracted Retracted 25 Inboard wing fences Unlocked Retracted 25 Extended Retracted 25

Basic wing (no fences) Unlocked Extended 26 Inboard wing fences Unlocked Extended 26 Inboard and outboard wing Unlocked Extended 26 fences Wing leading-edgechord- Unlocked Extended 26 extensions (no slats)

Basic wing (no fences) Unlocked Extended 27 Extended Extended 27 Inboard wing fences Unlocked Extended 27 Extended Extended 27 NACA RM @5E31a coNFIDmIAL 21

TABL2 III.- SWMARYOF R?SULTS OBTAIXD III+ISGSTP.IJ.AFPROAC~ OF TSE

I13UCIAS B55&11 RISEUWE AIP.PL4N2

Awe.rent l.wlt~..l .t@J1litY Pilot repor 0!-‘meet of ?e&Peak Minlnmm slat Stick-fixed Stick-fme Remarks mf isumtior buffeting, ~:; *A vi, mph vi, mph Statle Ikutr.1 Unstsble Stsb1. Iieutrel Unstable

Retracted Retrnctei vi : L85 vi2 170 .?1 : 170 ------Most of ------190 mummer

asicW-@ Unlocked Ietrcdc? ““81’”021‘5’1-”’’--=’” I Unlocked titeuiea Vii ’45 ------Vi $ 14’! Vi ~ 155 ------vi ~ IIL7 ~

------vi ~ 172 ------Meet of vi ~ 175 200 ‘“51”4’= ’40 Retract& R.trsctei vi 2175 mcamver

UIllcckedRetractti vi 2 m ------vi $ 161 vi 2 186 ------v~ s M Umvnilnbh lt.oal’dwing rem.. unlocked Extended Vi ~ 131 ------vi $ 151 ---. —-- Mmt of ------155 ?>.6I.JA I@ ~tch roll oscillationat maneuver higher *p.& . Oymaic lateral stabilitywgi- .,1 mt Vi < ’60 !qh. ---hI RiRM-tins heminese as stall qproc.chul. I T Vf: lm .-—-— ------W ‘4.3 ‘8 160 Erraticcontrol and response as stall ar.Pronched. I APpmrent Stick-fixed longitudium .tnbillty appeared *0 decrease at ,boerdad vi ~ 175mph. Fe ●rratic mtbmrd over entire mamuver. ting fmce,

Unlocked E&emWi vi; ti3 ------vi ~ 180vi& ’45 -—----- ‘4> 18.51.40 131 Erratic control d response d vi< 1113qh. L.2rt- ::m:~-. M stall

1 -1-vi2 1* ------vis 167------no.t of ------. alm mmneuver

‘ata filly ix-tended Iktedd lExtetied vi2 &’ --.----——-- Vis lh9----.------vi ~ 15c 19.51.112 :. wins !emes)

Rtmdei etracted Vi L’@ v~:lta vi 2 169 ------vi: 16$ K!4 L8.3 1.17 149 I ‘atsfu14 vi z 167 tided L@ lr,toti ------UOst 0? ------. 147 4-I18.7 1.45 ’27 Rterded Viklz’r ’45> vi > 135 ------finsfences + muwuver I

viz 197 vi i 170 vi ~ 170 ------VI ~ 1?5 vi s lE 15.0 0.98 161 OILlng.mclllationat Pvi z 185mph. lug lemilns *. .hord- !xtensiolls Retracted Emended b milli------__------Vi ; 15> ----—- v~ S,153 160 ‘1.8 1.12 152 oiling (xcillatlonduring mum speed entire malmuver. R&m_ VLng henvlncee. T T r % lot report of heavy buffeting.

CONFIDENTIAL Iv N

L-87973 Figure l.- Three-quarter front view of Douglas D-558-II airplane. NACA RM H55E31a 23

● CO. \

Figure 2.- Three-view drawing of the Douglas D-558-II research airplane. All dimensions in inches. .

CONFIDENTIAL 24 CONFIDENTIAL NACA RM H55E31a

. v (.%

%lrn Oal \ \ \ \ \ \ \ \

uodmuas

.!+ El

cONFIDENTIAL A.,

L4797L Figure 4.- Photograph of the D-558-II wing) showing the inboard and OUt- board fences (stall-controlvanes) on the wing. 26 CONFIDENTIAL NACA RM H55E31a

Airplane ~

Wing slat

~Wing fence 0“m71+%a&F1.p.— Section at 036 bfi

Q“ \ . . F fully— ,.~26 slat <~’~- extended spoth of slot trovel I-4.95 Section A - A (enbrged)

Figure 5.- Plan form and sections of the wing of the D-558.11 airplane showing details of the wing slat in the retracted and extended positions.

colwIDENTIAL NACA RM H55E31a CONFIDENTIAL 27

/ /

,. ..i“ .!+

- ,.

I u“

CONFIDENTIAL 28 CONT’IDENTLKL NACA RM H’j5E31a

\ \ \ \ \ \ \ \

o N In o

t 0.68 b/2

9.25

Wing chord extension Originol wing profile

Wing section at stotion 102

Figure 7*- Plan form and section of the wing of the D-558-II airplane showing the wing leading-edge chord-extension configuration.

CONFIDENTIAL NACA RIvIH55E31a COIIFIDENTIAL 29

CONFIDENTIAL NACA RM H55E31a

3 N

1 ,8 -P

—D g

\ m

I al & AL

ql’~2JOJ UO!+3!JJ JOJDAa13

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 31

CONFIDENTIAL CONFIDENTIAL NACA RM H55E31a

@ 20 up t$e,deq 4 0 0 1 0 0

I n

I o a, deg -+li@+&

B@Ix@

1.0 @

.8 ;

CNA .6

n,g

~ 60 170 180 190 200 210 220 230 Vi, mph

(b) Variation of Fe, be, a, CNA} and n with Vi.

Figure 10.- Concluded.

CONFIDENTIAL I

? NACA RM H55E31a CONFIDENTIAL 33

in l-l x!

l-l k-l

CONFIDENTIti- CONFIDENTIAL NACA RM H55E31a

20 Pull

Fe,lb O

8 up

8e, deg 4 o 0

w 12

a, deg

8 El= -1-

1.0

CNA

220 230 240

(b) Variation of Fe, be, a, CNA, and n tith Vi.

Figure 11.- Concluded.

CONFIDENTIAL 40

PI / I R#’ +1 t4amWJbIFa ~ .,..-, .,,...,< ~q., .>.-...... ------.-.. -.’------.;/.& k- ;>,:(.. >,\F * . . — \ II 5A F,, Fr, !b />.+= . ..= ...... -, \ --- .-l-T-” “-”-”714——____ - . -J — ~.v u t 3! L J - -/ e F!#’d ...... ,. ------w 8, . . ------””” ““””” .: . _...... - 4 ,——..... ---- .-.-.. . ..-...... —————-- -, +——- vmPr .- ...... ------“---”””” ““-””’ _=T. —---______——.——- b———–———————-———-——————- /. . ———------—- -—— ____ ----- 0 L \ . — . / ‘ i .

L 4

mm J . . . ..--. -l--- . . ..—...... ------...... -~;;- cw’ ------~,lm ...... ----- ...... ------~ .4 0

/ L + — ~ T7- -- o--c ) --% .,,7 - * +.44,,mambk” 7=0 w + * 74?

8 ,4 0 -’\ .-. 1 — -— -’G”- v“=- — — -— -“--’- — — v .--’-- E.de ~- -“”- ‘-’’=” “J’- - Left . 16 4

/ ‘

12 / A /-—— . . * \ .

8 IA s /

/ ---’ \L ‘ / - — 4 12 - J / y -_/” y I -—

0 10 — ‘

% A %_ 4 -~ ~ /

,8- ~ -“-- “ — — v ---’- ~ 2 6~ “ L -- n, a

Y 0 2cm — — — — — — — ._ — v, , mFl!

,4 103 M

M M 72 76 w 04 69 44 48 s? 56 60 64 .2 24 20 32 36 40 0 4 s z 6 m Thm,l,lu

(a) Time history.

Figure 12.- Flight characteristicsof the D-558-II research airplane during an unacceleratedstall. NO fences on; slats ~locked; flaps extended; landing gear e~ended; it = 1“5°; center ‘f ~avity at 0.260E;~ = 19)000 feet. CONFIDENTIAL NACA RM H55E31a

Fe, lb 8*Q up @cm3c K+=J

Se, deg 4

() o’

a, deg

1.2

CNA 1.0

.6 o-n~ ,,. . . . I n,g

o 130 140 150 160 170 180 190 200

y, mph

(b) Variation of Fe, be, u, $A, and n with Vi.

Figure 12.- Concluded.

CONFIDENT NACA RM H55E31a CONFIDENTIAL 37

n , ‘1, J \-

Tme, t, sec

(a) Time history.

Figure 13.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Inboard fences on; slats retracted; flaps retracted; landing gear retracted; it = 1.30; center of gravity at 0.264E; ~ = 20,000 feet.

CONFIDENTIAL 38 CONFIDENTIAL NACA RM H55E31a

20 “ Pull && ‘J% o 00 0(“%oo~ - 0 Fe, lb O k LJ o

% “) 20 ‘

8 u m up

)3e,deq )

00 0 16 4 n o () o 0 12 w (

a, decj 8 ‘T”

4 K @o 00 .[ 0 CNA .( $

)oQ& w o n, g

r------170 10 190 200 2 )

(b) Variation of Fe, be, a, CNA) and n tith Vi.

Figure 13.- Concluded.

CONFIDENTIAL CONT’IDEIWt’IAL 39

Riiht ~ ‘e...... !%11 ,-. , . ..’ ‘: .,,, /-~ Fa 0 - ,-- . --. ,’-- . u- ~ v- . w L --J r-. v- “’ \ , .~\J ‘, // ~,~,Fr,lb , +\b,”\ ,~\G. —-/ ‘ \ .- [\/- “ f, “./ , ._/fl\ \d~G L{ \\/ ‘\ / i—l Al 2C-

8 R!ght ‘,, ,----- ...... -’ ... 8.?.. ------.:’ ‘!, /,”’ .. up ... \ ,: ‘... .. : ,’ : : 4 ,, ., 80 ~Q&&, deg 8, ____ _—— - .— -—- ———. .—— — ———. .—— —. -——— /— ___ -— 8 o

/ Open4 Right ----- ~~ ‘ 8~ ,in. . . /“ Lef

16’ /\ \ \ / 12 a a, deg

/ “--’ 8 A / —- -’-

4 \ i / I --’ \ I .8- %~ CNA .6 v .~ 2 .e n,9 n / ---- .

0 2s3 Vi, mph v. — I---=,r

.4 M

.2 -4 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 lime, t, sec

(a) Time history.

Figure 14.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Inboard fences on; slats unlocked; flaps retracted; landing gear retracted; ~ = 2.1°; center of gravity at 0.2556; = 21,000 feet. \

CONFIDENTIAL ko CONFIDENTIAL NACA RM H55E31a

UP 8e, deg

161

a, deg 12

12 4

1.0

CNA .6

C3Gln I r o m CPu UUJ u w

J n, g 150 160 170 180 190 m 210 220 230 2Q ~,mph

(b) Variation of Fe, be, u, CN*~ and n with Vi=

Figure 14.- Concluded.

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 41

Rqht 20 Pull

~,~,FrJb ,...., 1; ..... 20 .’ .....,,.,,, ..... ,,,, .. 8. ... ,, ~. ,., Right ,-.. . ..- ---- up ...... --’ ie““”” “-””- ‘“ .....’------,,fl.’”;r_ ,,, — 1 -. 4 ( — 8a,8e,8r ,deg ——— —. [

f- 4 J/’ 4 Open Left 8s, in. A Righ$ 0

@,mdia%%ec Ydw Vslacify unmaiIabk -J& ~ ~ &w ~w \r \- ~ ~~~ @=yj ‘Qy_7 ,,, ‘$ v “ -. ..,,’

r \ I 4 (1, I W 20

16 \J

/ n [. 1,41 Rqhi 2 up \\ll I 8 J J v ‘ \_/ ,,., a&’,dsq : ,, !; \ II IQ 4 2 - CNA ::

n ~ ,-, : ,, ,, : : : ‘; qA8 C’ ., .. .. “’.,.. -..’ . ....-”. ..-.., ...... f...... -.... ---- ...... ; ,,,/ :,, v ; ;, ,, ,,,’ !,, ,, ‘...’ ,6 4 ‘ /

,4 8 v n n, 9 — ————— — 1 0 y ,4 I ls~ / M M ~ ,mph - — .2 50 0 4 8 12 16 20 24 28 32 36 40 44 @ lime, t, sec

(a) Time history.

Figure 15.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Inboard fences on; slats unlocked; flaps extended; landing gear extended; it = 1.4°; center of gravity at 0.2535; ~ = 21)500feet.

CONFIDENTIAL CONFIDENTIAL NACA RM H55E31a

20 Full

Fe, lb O

12 20 up

&,deg 8

a, deg

cN~

n, g

Vi , mph

(b) Variation of Fe, be, a, CNA) and n with Vi.

Figure 15.- Concluded.

CONFIDEFJTIAL NACA RM H55’E31a CONFIDENTIAL 43

r- /\ Righ?O-

~ ,Fe,Fr,lb ““: f --

...; ,.... -.----, Right 2 ------. se ..... ------~ up ..-. .._-....-...... _ ..... ------/’ ~, f3e,Sr,de :,, :,‘. .’ 4 80 ;,\,,-,...... 1° ‘L ‘AL - ;- t -n ‘ /-\\ ,/(‘ - - /— ——\ /- 8,L 1.——— 01 ‘,, , Right’4 ‘— ,... up &Ill ~,e,~,mdia[

Right 4 ~,deg

A / I

/- 10 1.0

a ,deg 6 ,8 / o / //%A CNA \2 6‘ .

.4 u n 7 k // .2‘

2 0 Vi ,mph

1007 4— — — -M M

e 0 4 8 12 20 24 28 32 Tme,t,’:c

(a) Time history.

Figure 16. - Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Both fences on; slats retracted; flaps retracted; landing gear retracted; ~ = 2.3°; center of gravity at 0.2625; ~ = 21,000 feet.

CONFIDENTIAL 44 CONl?IDENTIAL NACA RM H55E31a

Pull

Fe, lb

8 up

~,deg 4

0 0 16

0 o () (‘)o 0 12 ‘0 co “.O ~%% El < ,@o &J 8 — — — k % 80

4“

10 8

0 .8 n

CP o CNA 8 .6

ri, g

180 190 200 210 2; :0

(b) Variation of Fe, be, a, CNA) and n tith Vi.

Figure 16.- Concluded.

CONFIDENTIAL NACA RM H55E31a

.,9 n

o- v, 150 4

VI ,n@ M M I

50 .?6 I I I I 4 8 12 16 20 242632264044 42 525660646872 76 IiLna, t,aa

(a) The history.

Figure 17. - Flight characteristicsof the D-558-II research airplane during an u.nacceleratedstall. Inboard and outboard wing fences installed; slats unlocked; flaps extended; landing gear extended; ~ = 2.3°; center of gravity at 0.262E; ~ =20,500 feet.

CONFIDENTIAL 46 CONFIDENTIAL NACA RM H55E31a

20 u o Pull C)” 8 &@ ,~ ~% . ,@@ kqoc? %m@ o 0 0% “ n o 0 Fe,lb O 0 “Co “ o 0°

8 up

8~, Cleq 4

16- ;OU “o ~ o 0“ o 0 0 12 0

a, deg 0% m ., n 8 Q o “e “ ‘o%, , 00 4 000 0 u “o o o 1.2 0: k

1.0

w CNA .8

E n I -@’~ CLJ Ou v Oa( \ o

~30 140 I50 160 170 180 190 200 210 Vi , mph

(b) Variation of Fe, be, a, CN , and n with Vi. A Figure 17.- Concluded.

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL

Right 20 *, /1 _ -\ F, Pull \ ,[,’:’ ,)....-/.’;.. ..y\ ,{.J..,, \< .j,w :> ~:;. -’i, “~,’_: J- ( ,., _-’ V.,, e .,.. fih o ~ ~ ~ ‘.—. .++ -- v v w “~ .;, ., s,’ ,, ~, Fe,Fr,Ib

a Righte I --- .. .. . ,. ,.: up .,. ---- ~~,.e8 ‘ “. ; ,“‘,, ,’ ‘, ,, ., ., ,., ,“:,,; . .,, ;, : ,,, ,, ,,. ,, ,.’ ,,, ; 4 :,,’::. ,, ~,se,s, ,ljq ~. ______.~ ~ \– ~ ~ “’% p- “’ ““y–‘–– ---- –’-–- :-~”: + % \ r- 0.4 u Right u ~,i,tj,m%skc 4 07- A...... A“--- -- i 8

16 / \/ \ a,dq

12 12 / \ \

1.0 8~ / ‘-” \ c~A

.8 / \ \

.6 2-—-._,- - n,9 n - — \ w 2cm— vi Vi, mph

.4 100 — M M

.2 0 4 8 12 16 20 242632364044 4652 56 ~me, t, sac

(a) Time history.

Figure 18.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. No fences on; slats fully extended; flaps retracted; landing gear retracted; it = 1.6°; center of gravity at 0.253E; ~ = 21,000 feet.

. 48 CONFIDENTIAL NACA RM H55E31a

1 Pull 20 I o o 0( cP(IOCD o o & o o 0°00 00 ~o (30 0 Fe, lb ~ ~ 00 o

F + 8 20 up . 00 q-j 8 0 8e, deg o 8 - ~Q30 0 0° 4 o“ c o

; 20 “% “o @

) o 0 00 0 “(33 — 0,-, “deg 12L-E’ o ) ‘o () + 0% ~ e 1.2 8

1.0~ o u 0 o CNA 0% 9° 0 Om o .8 0 00 ) “0%

n .6‘

n CD. I “ 0’

~v9

180 190 200 210 ~, mph

(b) Variation of Fe, be, a) CNA> and n with Vi.

Figure 18.- Concluded.

CONT’IDENTIAL NACA RM H55E31a CONI?IDENTIAL 49

2G 1

11 ‘ /- ----/=’ 16 a, deg o / ‘“- \ 12 /“ /’- + ~ 7 8 — /’- I I.2 / — ._/- CNA / ID / I.0

CNA

b ‘

.61 r ‘“ “

2 n,9 n ------200 0 vi ~ ,mph

100 .4 M M

% 4 8 12 16 20 24 28 32 36 40 44 * 52 56 w W ?ime,t,sec

(a) Time history.

Figure 19.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. NO fences on; slats fully etiended; flaps extended; landing gear e~ended; ~ = 1.6°; center ‘f ~avity at 0.249~; hp = 19,000 feet.

COITFIDENTIAL 50 CONFIDENTIAL NACA RM H55E31a

Pull 20 Fe, lb

20- % %’ 0 16 y 00 a, deg C@mo o 0 12 n

8 v 00 0 00 0 00

Q&o %qo cN~ ! a (‘% Q300 Uo 00 o 0 0

. 1,~“o 00 oo~ Uo o

m 9

930 140 I50 160 IX) 180 190

(b) Variation of Fe, be, a, ~A, and n with Vi.

Figure 19.- Concluded.

CONFIDENTIAL NACA RM H55E31a CONFIDENTIAL 51

\ Right 20 1 1- ,\u [ ,.~ (.....; ,..?. -., Full . 1’ Fr) ,7 J \ ~,~,Fr ,Ib ( “J-7 -~ \ /“” ,, ;’” / C3 ,. \ \ / v- “ (V ‘,..,’ .,

Right 8 up ‘, 4

Right4 ..-

& B_ 0 .4 w n /\ / 16 / \ / /

/ ‘ 1 1 I 1 a,deg 12 Q f-k-t-i / I / / \ / I,2 8 ‘

\ /

c~ -Y A ‘A

200 Vi ,mph .4

10Jo~ : ‘ ‘ ‘–

%04811216 Tree, t, sec

(a) Time history.

Figure 20.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Inboard fences on; slats f~ly e~ended; flaps retracted; landing gear retracted; ~ = 1.6°j cent= Of gravity at o.21j6E;~ = 21,OOO feet.

CONFIDENTIAL 52 CONFIDENTIAL NACA RM H55E31a

Pull

Fe, lb

up ~e, deg

20 —.

~oo

o ( ) 16 o o ( ) a, deg 00

~ on 12 f> o 0 0 0 tia3 8

1.2 0 0 0 () o 0 Lo () o Oa CNA @o o .8 () n o 0 %(D .6

o Q )~ I -n n~ @Q) ()W aDxmm

r-l, g 0()

0140 I50 160 170 180 190

Vi, mph

(b) Variation of Fe, be, a, CNAJ and n with Vi.

Figure 20.- Concluded.

CONFIDENTW-L NACA RM H55E31a CONl?IDIINTIAL 53

lligh~o .....?. Pull ... f’”)+;i...... ‘“ ,’” “’f ...... ~/ \ / -% r--- Y 0 A ~ / ,.., A– J“ ~ -/ v “ “= Fa,Fe,Fr,lb ‘\fi, “1, ‘Fr ‘lv’ \ I G–1-”’” ‘b/ , I Right 8 20 ,----,...... / ~ ...... ------. . up % ..,’ ...... ’---- ”-- ‘,, ,,.------/ > 4...... % %},}r,deg /— -.— /- -—. .—2 , \ / Isr // 0 / =- ______/

4 ‘#’+ or -‘===== -~ ~...... = ----- .~...... —.. I%(J4 9 /3,deg @,~, radianskec B / — . o k% .4 ---- / \

16r

a, deg

12 / a \ /,“ -’” \ 8 \ ‘\ 1.2 \._/” /

CNA I,0 \ CNA

.8 /’ — d 2? n n, 9 \ _

200 0 — _ Vi ,mph y

1 I I “1 rT----t-+--P-- I .21 I I I I I -4 0 4 8 12 16 20 24 28 32 36 40 Time$t, sec

(a) Time history.

Figure 21.- Flight characteristicsof the D-558-II research airplane during an unaccelerated stall. Inboard fences on; slats fully extended; flaps etiended; landing gear extended; it = 1.6°; center of gravity at 0.2’52E;~ = 20,200 feet.

CONFIDENTIAL CONFIDENTIAL NACA RM H55E31a

Pull Fe, lb

up 8e, deg

16 a, deg 12

)CQ3 ‘Q o 14 4 +

1.2

CNA

1.0 ‘%00 %3

--Ts

? 20 I ) 140 o ) )

Vi, mph

(b) Variation of Fe, be, u, CNA> and n with Vi.

Figure 21.- Concluded.

CONFIDENTIAL RM H55E31a CONFIDENTIAL 55

Right20 I f./==, I ,-. .-., Fe Pull .——_

,, Right 8 ...... up / $+._ .------...... - .... ---- ~ ...... 1 .....------”------,--, ..

,deg ~ %/ t- ~)e)r -— _- ——— ——— — 8, 0 u ,,.,,

Right “4

~,h,$, mdi~r%sec o———

R@lt B,deg o

16 4

12 a, deg

4 1. i

CNA 6 1=

2 .2 n, 9

0 k

250 Vl, mph VI

I50

.4 M M

.2 0 4 8 12 16 20 24 28 32 364044* 52

Time, 1, eec

(a) The history.

Figure 22. - Fiight characteristicsof the D-558-II research airplane during an unacceleratedstall. No fences on; flaps retracted; landing gear retracted; chord-extensionson; it = 1.6°; center of gravitY at 0.228G; $ * 20,400 feet.

CONFIDENTIAL 56 CONFIDENTIAL NACA RM H55E31a

P“1120” lb () Fe, ()0000 00 o cR@ Qm8q .$p ~ 00 )0 0($ @ 0 o u u o

16- 0 00 0 c~ a, deg 12 “o~ OQ %00 )o~ 8 .@- % ~~% Om

1.0 000 0( ) 0 00 .8 Uyn CNA ’000 Q ‘0% b Q-J .6 Dco~ OQ)

I-@+-& ~=j~ m-Jc ~ ~ ~weu c=

n, g

0 160 I70 180 190 200 210 ; o 230

(b) Variation of Fe, be, a, CNA, and n with Vi.

Figure 22.- Concluded.

CONFIDENTIAL ? NACA IOJ~5E31a CONFIDENTIAL 57

20’ Rqh! %1I ~ ., Fe .Rw<...... -.. . ,2<. /-. .: FO,Fe, Fr,lb ., F,x .:_ ;+ . /

b’ VY IQ ~\ w - ~- 4 F.

m! 8 20 up .--’ : :; ...... - -- . ..: : 8...... ---’” 4 ...... -. -. .,, ,. . S+& , Oeg ;,. 8, >A n (--=._ % n ——— ———. .—_— AJ ‘ -- < 0 —— — ~ — = V- - / I —

4 \J

Time, t, MC

(a) Time history.

Figure 23.- Flight characteristicsof the D-578-II research airplane during an unaccelerated stall. No fences on; flaps extended; landing gear extended; chord-extensionson; ~ = 1.6°; center of gravity at 0.224E; ~ ~18,700 feet.

cONFIDENTIAL CONFIDENTIAL NACA RM H55E31a

Pull Fe, lb

& deg

o 0000 000 00 0 L

12 0

4’

00 T000

7 Q=

I 00 n,g

c I I I 3 160 170 180 )2(33 210 220 m

(b) Variation of Fe, be, a,, CN , and n with Vi. A

Figure 23.- Concluded.

CONFIDENTIAL 8e, deg 4

4 8 12 4 8 12 16 4 8 12 16 4 8 12 16

a, deg (d) Wing chord-extension configu. (a) Basic wing configuration; (b) Inbocrd wing-fence configu- (c) Inboard and outboard wing-fence ~ = l.>O; center of gravity ration; it = 1.3°;center of configuration; it . 2.3°; center ration; It s 1.60; center of of gravity at 26.2 percent F. gravity at 22.8 percent ;. at 26.7 percent E. gravity at 26.4percent E.

Figure 24.- Comparison of apparent stability and lift characteristicsof the D-558-II research airplane with various wing modifications. Wing slats retracted; flaps and landing gear retracted. v 60 CONFIDENTIAL NACA RM H55E31a

— U3

a — -

a 0=

CONFIDENTIAL Jan Q I,4

I .2

100 CNA

.8 ~

.4 0 4 8 12 16 0 4 8 I o 4 8 12 16 20 24 0 4 8 12 a,deg (c) Inboard and outboardwing-fence (d) Wing chord-extension configu- (a) Basic wing configuration. Inboard vlng.fence configurateion. (b) cofliguration. ration. (Slat.retracted.)

Figure 26.- Comparison of apparent stabilityand lift characteristicsof the D-558-II research air- nlane~-—. . . . with various wing modifications. Wing— slats unlocked; flaps and landing gear extended. , 1 1 1 up ‘

8e, deg

& & I.4 I 1 I n Jl— 1

CNA

Configuration ~ 0 Basic Wing O Inboard wing fence T TT

a, deg

(a) Slats unlocked. (b) Slats extended.

Figure 27.- Comparison of apparent stability and lift characteristicsof the D-558-II research airplane with various wing modifications. Flaps and landing gear extended.