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MAYu 1947.-

NATIONALADVISORY COMMITTEE. FOR AERONAUTICS

TECHNICAL NOTE

No. 122k .

FLIGHT ‘TESTSC???A DOUBLE-HINGED HOIUZONTAL TAIL SURFACE WITH KEKERENCE

TO LONGITUDINAL+YVXBILITYAND -CONTROL CHKRACT31RISTIC$

By Carl M. Eanmn and Seth B. kiderson

Ames Aeronautical LaboratoryMoffett Field, Callf.

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I WashingtonMay 1947

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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

TECHNICAL NOTE NO. 122k

FLIGHT TESTS OF A DOUBIJ%EINGED HORIZONTAL TAIL SURFACE WITH RRFXKENCE

TO LONGITUDINAI+TABILITY AND -CONTROL CHARACTERISTICS

By Carl M. Hanson and Seth B. Anderson

SUMMARY

A double-hinged horizontal tail was teBted in flight on a small 1-speed airplane to determine the longitudinal-stability and -control char-acteristics. The center portion of the horizontal surface served as ~adjustable trher and the rear portion as an elevator. Test dati wereobtained for various airplane flight conditions, botQ with and without ~elevator seal installed.

The flying characteristics of the airplaue equipped with the double-hinged horizontal tail surface were generalJy satisfactory. Optiniumflcat– ....,ing c&racter”istics for the elevator are dependent cm the ccnfiictirg re- _.quirments imposed by the conditions of wave-off, recovery fran a stall,

. trtmming to low speeds and landing. —

The pr$mary effect of removal of the elevator sealwas a decreasein the elevator effectiveness. .-

lXTRODUCTION

The problem of attaining adequate longitudinal control has beccmemore cunplex with the use of heavily flapped aircrafftand the necessityof providing for a l~ge center-of~atity travelt A possible solutionof this problem is the use of a double-hir~ed horizontal tail,

It c- be”shown that with the double-hinged horizontal tail it ispoesi%le, witliou%“incr’easihgthe horizontal-tail area, to obtati improvedstick+ree stability characteristics, greater tail loads for lezidingandmaneuvering, the ability to trim to lower airspee(ls,end lower stick-forcegradients. . .

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2 NACA TN No. 1224b

This investigation wae formulated to obtain frcm flight teets resul.tethat would indicate sane of the advantages and disadvan’%ggs of this ~pe *

of control which were not appreciated in the design stage. The conclusionsdrawu from the test data have been verified end amplified by pilot cpinicnwhenever peesible.

While this type of tail surface is more applicable to heavy aircraftrequlrln~ a large center-of-gravityrange, it is felt that the resuitspresented herein will tieof ;&l.ueforthe critical features of the destgn.

IX3SCRIPTIONCll?

The airplane used to investfgate

fGt&e test work and will Indicate

TEST EQUIPMENT

the characteristics of the double-hinged tail was a twc-place, single-en@ne, midwlr!, cantilever mcnoplamequipped with a conveqtional fi~d-tyye landing gear. A description ofthoee features of the airplane pertinent to the investigation is asfOllowe:

wingArea (including section projetted

w

through fuselage), sq ft... . . . . . . . . . . . . . . . 261.9Span, ft . . . . . . . . . . .c*. ,*e***, **a. . . 35.89 .Taper ratio .,....,. ., . . . . . . . . . . ..O .0 1.5:1Aspect ratio . . . . . . . . . . . . . . . . .. O.... ,, 5.1:1SectionRoot . . . . . . . . . . . . . ..o O.. ,,o”oo-o, N&A 23015 -

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Tip . . . . . . . . . . . . . . . . . ... . . . . ,, NACA 23009Incidence)deg . . . . . . . . . . . . . . . . . . . . . ..O.M.A.C., in . . . . . . . . . . . . . . . . . . . . . . . . ,..a~~~Dihedral (outer panel chord line), deg . , . , . . , . . . . . . 7,0

Mcdlfied horizontal tail (includingstabilizer, trinzner,and elevator)Area (includir~ 3.8 EIqft covered by fuselage), sq ft . , . . . 59.4Spen, in . . . .. o... .**em. **. **=o. ● C. 187.75Aspect ratio . . ..~. ~ . . . . . 6 . . . . . . . . . . . . 4.05Incidence, deg . . . . . . . . . . . . . . . . . . . . . . ,0Airfoil section . . . . . . . . . . . . . . . . . (A~rox. NACAOO;5~chordRoot, in . . . . . . . . . . . . . . . . . . . . . . . . ,. 31.5Tip, in. C.. .,. O.O. ., . . * ., .+.,,.,, , 37.4Average, in...,,.. . . . . . . . . . . 44.4

TrWner (sesled,movable oenter section, zero ae;&l; ;e&&and radius nose)Area eft of hinge line (includingO.~ aq ft

covered by fuselage and excluding elevatorarea), sift...., . . . . . . . . . . . . . . . . . . 12.3

NACATN No. 1224 3

4

Percent total tail area . . . . . . . . . . . . . . . . . . . . 20.7

Average chord aft&~e line, in.. . . . . . . . . . . . . . 9.6%Percent avers.gettilchC~rd . . . . . . . . . . . . . . . . . . 21.5

Travel (max.). . . . . ...= ..o=o**o**=*c*=” OO ~19.0° down

ElevatorArm tit of hinge ltne (excl~i~’ exea

covered by fuselage)sqft .“. . . . ...090-0 .8.*c==~~~~Percent total.tail area . . . . . . . . . . . . =..OO c**Elevator lalance=ea, sqft . . . . . .. i....=.* ..-. z:6

Percent aerci@amicbsJ-=ce . . . . . ... . ...= ● -COO =.6

Type of bal-ce. . . . . . ●“ . ● o ● ● ● ●“- “ ~- ‘e~ed).hl~~ ‘ver~Chord aftofhinge ltie(c-tant), ti . . . . . . . ..s. sPercent average tiflchti. . . . . . . . ...=.**. . . 21:3

Travel (max.). . . . . ...= ..00~=o”o*c”**”27*5021.7 d=

R~tq,~o-........ . . . . . ..=. uoobhpat 2200x’Pufr~S. L. to 5500 ft

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A three-view drawing of the airplane is shown in figure 1. A pho*. gra~h of the airplane instrumented for flight tests is given in figuzze2,

end figure 3 is a photograph showing various positions of”Hi5 “hor~zmtalconlrol surface. To eliminate any tendency of the separate halves ofthe elevator to assmne clifferent angles (because of pley inherent inthe actUatin&JIllSChSIliSIU), the IWO portions of ,the elevator were connectid _rigidly together by a strip at the elevator tiaili~ dgq,. Tkm mechanlceof the elevator system were such that the range of elevator b-fleeticn(relative to the &tier) was independent of the trimuer setting, Frictionin the elevator control system was less than one-lmlf pcund, as measuredwhen the control was moved slowly through the neutral pceition ‘@ noload on the surfaces. Tke v=iaticm of elevator angle with stick pos~-tlon aE measured on the ground with no load-applied to the si&faces isshown in figura 4 ● The trhmer drive mechanism was han3-operated franthe cockpit through a cable-chain system. The mechanical advantage was –such that 1.0 turn of the contiol handle (on a 5-inch arti]w&s requiredto change the tiimer angle 1°. Plan and section views of’the horizontaltail are shown in figures 5 and 6, respectively.

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The selectim of the chords for the trimmer and elevator was based up-OL the results of wind-tunnel tests of current designs. The area of thedouble-hinged horizontal tail was chosen appro~tely equal te tio areaof the wiginal horizontal surface of the test airplane. This was acc-,yllshed by the additicn of the trimner section, a redesign of the hori–zontsl.-tailtips, a reduction in span of the original tail, e-cda .mdi-fication of the elevator incorporating a ccr@.an%hord design..

NACA TN NO. 1224

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INSTRUMENT INSTALLATIONs

Data presented herein were obtained by the use & standard I?AC.4@m-tographicallyrecordin~ instruments s~hronized by a otandard NACA timer.The elevato~position recorder was connected to the push-pull tube systemnear the tail. It is believed that no appreciable deflecti.cnin the push-pul.L-tubesysteinoccurred between the elevator and the point of attachmentof the control-positionrecorder. The trimmer-positionrecorder was con-nected directly to the control surface.

Indicated airspeed was determined from the readings of a stendardNACA free-swiveling airspeed heed mounted approximately one chord len@hahead of-the wing leading edge and located_near the left wi~~ tip. ~dicated airspeeds given in this report have been corrected for positicnerror.

SYMBOLS

The following list-of EIymboleis included for reference:

normal acceleration factor, ratio of the net aero~amic forcealong the airplane z-axis [positivewhen dtrected upward) tothe weight of the airpleme

longitudinal acceleration factor, ratio of the net aerodynamicforce along the airplane X-axis (positivewhen directd fopward} to the weight of the airplane

trmr angle, measured.with respect to the stabilizer chord line,de~ees

elevator sngle, measured with respect to the trar chord line,degrees.

elevator control f~ce, measured at grip ofistfck, pounds

variation of’elevatordeflection

variation of elevatorattack

stallin~ speed

stalling speed

in the

In the

hinge+noment-coefficient with elevator

hinge+uoment coefficient with angle of

IandLng conditim, miles per hour

landing-approach condition, miles pemhour

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l?ACATN No. 1224 5

a

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& rate of chsnge of elevata angle with trimmer angle required foru bslsnoe in steady straight flight, indicated air@eed. con61i?n%

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TESTS

Tests were made in flight to determine the longitudinal-stabilityand -control characteristics of the test airplane equipped with thedouble”-hingedhorizonw tail surface. The various airplane ccnfi~ratiom er; defIned as foll&s:

A.ir-plsneconfiguration

cMJIib

Glide

Wave+3ff

Landing

Landing-approach

FlapsI

Power(hhp)

up

Up

Down

Down

Down

390

Enginethrottled

390

Enginethrottled

180

The airplane was”flown with en average gross weight of 4740 poundsat take-off ‘&d a center-of~avity rsnge‘from 22”.7_to30.5 percent meanagrodynmnic chord.

RES’ULTSAND DISCUSSION

The results of the tests to determine the dynamic and static lomgi–tudtnal-stability characteristics are preGented in table I and in figures7 and 8, respectively. The elevator control chsraoteristlcs ere preseritodin figure 9 for lsndings and in figure 10 for maneuvering flight, Trhn,changes due to variation of flays end power sre showx in table II. Fig-ures U s.nd12 present data showing the trimmi~ characte~tstics of the

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6

double+inged tail. The t3fff3ctof removingin figures 13, 14, and 15, end table II for

NACA TN No. 1224

the elevator seal i.eshownVerfoue tmst Condltlone.

Examination of the data presented in figures 7 to 12 and In tablesI and II shows that the longitudinal handling characteristics of the air-plane were satlsfactory except for the dynamic longitudinal+kbi lltycharacter”i.sties(initiatedby abruptly deflecting @ releasing the ele- .’vator con+xml) and a large forward movement of the stick (stick walkir~)when trimming to low speeds (flaps down, forward center of gravity).

The reason for the existence of the elevatar oeci.llationis notclearly understood. It Is believed, however, that this oscillaticm isnot peculiar to the double-hinged,tail and, therefore, further ts~timg ‘to isolate the actual,oause of this oscillation was not carrifidout.

The prol)lemof .adJustingthe elevator floating characteristics asthe airplane is trhmed to decreasing airspeedB in the landing &cd le.Ed-i~approach conditions &flight (figs. 11 and 12) is basic for thistype of longitudinal control.1 Not only did the pilots obJect to thefcrward movement-of the stick because of the possibilit~ of loss ofcontrol in a wave~ff or Inability to recover from a sijdl, but the mini-

mum trim epeed in the landing condition was ltiited by the elevator travel.,

TO more fully investigate the wave-off ccq@ition several wave-offswere performed at altitude. The results of these tests for the forwardcenter-of~avity position, not presented herein, indicate that only a

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mall amount of additional down-elevator (order of 1° to 2°) was needed,providing sufficient ma.rglnwithin the available down-elevator deflec-tion for adequate cmtrol. The adequacy of the elevator is attributed,in part, to the rcderate trimmer setting and elevatcm deflection re-quired to trhn at 1.2VSA in the approach.

To Increase the trim range to lower values of airspeed would requirea change in the floating characteristics of the elevata as the trimmeris moved. The choice of the float= characteristics of-the elevatcmas the tr-r is moved is dependent upon the opposixg requirementsfrom several conditions of flight: namely, the control in a wave-off,control in stall recovery, the ability to trim to lcw speeds and controlin landing. A discussicm of the foregoing flight conditicms is presentedin paragraphs 1 end 2.

1. If the elevata floats h the opposite direction to the trimmeras the Izrimmeris moved (elevatw floats down as the tiixuwm moves upas is the case with the tail tested herein) the abili~ to trim the air-plane to low speeds and the recovery chexacteristfcs in a wave-off or a

%Phia problem applies also to the adjustable ate.bllizer.

NACA TN NO. 1224 7

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stall msmsuver am affecte& adversely while the landing characteristics

. are tipromd. The wave-off and the stsJJ conditions may 36 criticsJ dueto insufftcient dcwn-~levator available, while the lsnd~ charm terisbi:sshould improve becausa of the up-trinmer deflection present end cmse@ent-IY the increased range of up-elemtor angle yet available.

2. If the elevatozz does not change its angular relationship W1th thetrimer as the trtier is moved (C& . O), the ability tc trim the alz-

plae to lower speeds is increased and the wave-off end stell cccditionsbecome less critical; however, the contiol in landings 4S affected ad–vorsely. In tb! design of a double–hinged-tall surfa~e a camprcmisemust, therefore, be made between the preceding items by adjusttig tl.e&’m–dynamic bslance of the elevata to give the desired floating ch&.ra~Terie-lxlcs.

The effect of the removal.of the elevator seal on the elevator COPtrol power, tinetrar effectiveness, ~d ~he ele~tor def~ecti~ r9–quired to offse+ a given trinmer deflection is presented.in fig~es .13

These data indicate a mrked reduction in the ab~l~fj or tEo----.~~e~~&r to balance the airplsme in the presence of the groti (fig. 15)when the elevator seel is removed. In addition, the effectiveness of

, tie elevator in off~etting movement of,the &@er w rgdu~ed bY 18percent (fig, 13). Eowever, this change ha& practically no effect on &“ability of the tri?nmr to trim the airplane throughout the _speedrenge

● and cn the desirably low trim force changes due to pgwer and flaps (ta%le11). The number cf cycles required to damp the short-pericd elevatorosc~ation ~~s refiu~ed slightly by tie removal d the elevat.cn?Hed.-(table I).

CONCLUSIONS

The results of +Ae flight tests ar.dthe data obtained frcm pilottsopinicn of a double-hinged horizontal surface ir:dicatethe follotirg:

1. The flying characteristics of the teet airplene equipped with thedouble–hinged tafl were generally satisfactory.

2. Undesirable flying characteristics of the test airplane were un–satisfactory dsmping of dynamic longitudinal oscillati~s (t?~s ~’asnotconsidered characteristic of this type of control) and lerge f~movement of the stick when trimming to low speeds (flaps down, forwardcentemaf~avity position).

3. The choice of the elevator flcatir. characteristics as the trk. mer is moved is dependent upon the conflicting requirements for tie c=-

trol in wave-off, contiol in stall recovery, and the ability to trim tolow speeds as opyoeed to the requirement for sufficient elevato=ontrol

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power in landing.

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NAOA TN No. 12E14 l-./t37+. --j Fig. 1

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Three-view drawing of thd test airplane equippedwith a double-hinged horizontal tail.

. . . d .’

-., .,, , -y ,;8I .Wl”” ‘-”’ !.:/Jl‘h .- -’ . . . .1.... ....

Figure 2.- The double-hinged hOriZOd~-tdl surface Ine.tailed on the test airplane. ~lK.

a)

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( ~) Trimmer full down, elevator full up.

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(b) Trimmer full down, elevator full down. ~

lMgure 3.- Side view of the double-hinged horlzont al-tail Burface, trimmer and ,?elevator defleoted. d

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(’c)Trimmer full up, elevator full down,

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(d) Trimmer full up, elevator full up.

Figure 3.- Ooncluded.

NACA TN No. 1224 rig. 4

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FOR AERONAUTICS

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NATIONAL ADVI$ORY COMMITTEEFOR AERONAUT108

NAOA TN No. 1224

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NATIONALADVISORYCOMMITTEEFOR AERONAUTICIS

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