1、_ JTECHNICAL REPORT R-57STATUS OF SPIN RESEARCH FOR RECENTAIRPLANE DESIGNSBy ANSHAL I. NEIHOUSE, WALTER J. KLINARand STANLEY H. SCHERLangley Research CenterLangley Field, Va.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ixCONTENTSPageSUMMARY . 1INT
2、RODUCTION . 1SYMBOLS . 2I. TECIINIQUES FOR STUDYING TIIE SPIN AND RECOVERY 5A. INTI:_RPRETATION OF RESULTS OF SPIN-MODEL I_ESEARCII_ 5Techniques for Study of Developed Spin . 5Langley 20-foot free-spinning tunnel . 5Spin tunnel as amdog computer . 5Interpretaiion of spin-tunnel results . 5Criterion
3、for satisfactory recovery_ 6Scale effect . 7Tunnel t.eehnique . 8Teehniques for Study of Incipient Spin 83. ANALTTICAL SPIN STUDIES . 8Methods and Calculations 9Equations of motion . 9Rotary-balance aerodylmmic data . 10Preliminary analysis . l0Effects of A1)plying Disturbances . 11Incipient Spin St
4、udies _ 14C. TECHNIQUES INVOLVED IN OBTAINING MEASUItEMENTS OFVARIOUS PARAMETERS IN TIIE ,PIN . 16Measurements Desired 16Methods for Obtaining Dal_ . 16Control positions, alt.itude, -tad rotationM rates . 17Angle of attack, angle of sideslip, and resultant velocity . 17Angular accelerations 20Linear
5、 accelerations . 20Earth-reference attitude angles . 20Determination of forces and moments . 20II. IMPOIITANT FACTOI/S TIIAT INFLUENCE TIIE SPIN AND RE-COVERY 2 lA. EFFECTIVENESS OF CONTROLS DURING SPINS AND RECOV-ERIES . 21Developed Spin . 21lleeovery From t.he Spin . 22B. INFLUENCE OF LONG NOSES,
6、STRAKES, AND CANARDS ONSPIN AND RECOVERY CIIARACTERISTICS 25Variations in Cross Section . 25Effect of fuselage cross section . 25Effect of altering nose cross section 27Conied Noses and Nose Appendages 28Observed effects on noses having circular or near-circular cross sections,inehtding str:tke effe
7、cts 28Effect of flap-type surfaces on fuselage noses 33Induced circulation :fl)out lhe nose 33III. CORRELATION OF SPIN AND RECOVERY CIIARACTERISTICS FORRECENT AIRPLANE AND M(-)DEI, DESIGNS 37CONCLUSIONS . 4-IREFERENCES . 45TABLES 47CIIARTS 53Provided by IHSNot for ResaleNo reproduction or networking
8、 permitted without license from IHS-,-,-TECHNICAL REPORT R-57vSTATUS OF SPIN RESEARCH FOR RECENT AIRPLANE DESIGNS 1By ANSItAL I. NEIttOUSE, _o4.LTER J. I_LINAR,and STANLEY It. SCFIEItSUMMARYThis report presents the status oJ spin research forrecent airplane designs as interpreted at the LangleyResea
9、rch Center o/ the Notional Aeronautics andSpace Administration. _Iajor problem areas dis-cussed include:(1) Interpretation of results o/ spin-modelresearch(2) ,b_alytical spin studies(3) Techniques involved in obtaining measure-ments of various parameters in the spin(_) Effect;veness oJ: coT_trols d
10、uring spins andrecoveries(5) Influence of long noses, stralces, and ca-nards on spin and recocery characteristics(6) Correlation of spin and recovery character-istlcs for recent airplane and model designs.Al_alyses are made of the existing problems andgeneral conclusions are drawn.INTRODUCTIONThe sp
11、in of an airplane and the recovery there-from, like any other nlotion, depend oil the forcesand moments acting on the airplane. A developedspin, in general, has been considered a motion inwhich an airplane in flight at some angle of attackbetween the stall and 90 descends rapidly toward%he earth whi
12、le rotating about, and with thewings nearly perpendicular to, a vertical or near-.vertical axis. Recently, however, high-speedfighters and research airplanes have apparentlyexhibited spinning motions at high speeds in whichthe center of gravity of the airplane has followeda ballistic path.At one tim
13、e the developed spin was consideredimportant as a tactical maneuver. At thepresent, however, the spin is considered significantprimarily because it is a motion that can beentered inadvertently and because fighter andtrainer airplanes are required to demonstrate thatthe developed spin can be terminat
14、ed satisfac-torily. Controls which are effective in normalflight may be inadequate for recovery from thespin unless sufficient consideration has been givento this problem in the design stage. In the past acriterion, based on research with many designs,was established for predicting spin recovery (re
15、f.1) and for determining the adequacy or inade-quacy of controls while the airplane was still inthe design stage. However, with the advent ofiet- and rocket-propelled airplanes and theaccompanying changes in weight and mass dis-tribution, it soon became apparent that thiscriterion couhI, in many ins
16、tances, be inadequate.Current airplanes have weights which are appre-ciably larger and have moments of inertia aboutthe I _ and Z-axes which may be 10 times as largeas those of World War II airplanes. It cannot beexpected, therefore, tlat a spin of a current air-plane, with its accompanying high ang
17、ular nm-mcntum, can be terminated as effectively as aspin of the earlier airplanes by aerodynamic con-trols which generally are of similar size. Also,because of short-span thin wings, the moment ofinertia about the X-axis of a current airplane isgenerally relatively low and this can greatlyinfluence
18、 the optimum control for spin recovery.Obtaining developed spins today is generally1 Supersedes recently declassified NACA Iiesearch Memorandum 1,57F12 by An_ha I. :Neihouse, Walter Y. Klinar, and Stanley II. Scher, 1957.lProvided by IHSNot for ResaleNo reproduction or networking permitted without l
19、icense from IHS-,-,-2 TECHNICAL REPORT R-57-NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONdilIicult but, when obtained, the same faclors thatnmke it difficult to obain tl,e spin may also makeit difficult to recover fiom the spin. Thus, it.may bc necessary in lhe future to resort toauxiliary means suc
20、h as extension of canards orstrakes, ws the parachute to be blownfree of the model. On full-scale parachute installa-tions it is desirable to mount the parachute packwithin the airplane structure, if possible, and it isrecommended that a mechanism be employedfor positive ejection of the parachute. W
21、hetherparachutes or rockets (another type of emergencyspin-recovery device) are used, provision isgenerally made on the model to compensate forthe mass changes associated with installation ofthe emergency device.538922-60-2Scale effect.-Models currently tested in theLangley 20-foot free-spinning tun
22、nel generallyrange in scale from ._40_/to ,20,_zand the corre-sponding Re3molds numbers of the tests (based onwing chord) range from approximately 50,000to 200,000. Scale may appreciably affect modelresults in two predonlinant ways. There is apossible effect, of Re._mlds number of the fuselage,parti
23、cularly if the fuselage nose is long and theprojected area of the fuselage is large relative tothe wing area. The cross drag on the fuselage ofthe model as well as a probable side force on thefuselage may be appreciably different from thoseon the corresponding airplane. This could havean important b
24、earing on the balance of pitchingmoments in the spin which, in turn, could affectthe balance of yawing moments through varia-tions in angular velocities. It. could also affectthe balance of yawing moments directly by avariation in what might be called an autovotativemoment due to tile side force on
25、the fuselage nose.(This effect is discussed in part IIB.) Also, thereis a possible Reynolds number effect on the wingsif the spin is sleep enough and the spin rotationhigh enough that the outer wing of the model inthe spin is near enough to the stall angle to beinfluenced in such a manner as to give
26、 less lift,than that on the corresponding airplane. Thiseffect could lead to a variation in the balance ofrolling moments and an accompanying differencein wing tilt in the spin. The magnitude of thiseffect wouhl be dependent on wing section, themagnitude being greater as wing thickness andcamber are
27、 increased (refs. 7 to 12). The differ-enee in wing tilt could, in turn, lead to a differencein the gyroscopic yawing momenls (/x-r)Pq inthe spin. In some instances, the Reynolds num-ber effects may tend to mfllify one another forexample, an increased incremental positive pitch-ing moment on the mod
28、el may tend to cause theinner wing to be depressed, whereas a decreasedlift on tile outer wing may tend to cause the outerwing to be depressed. In specific cases, however,the possible individual effects would have t.o beconsidered. In the past, based on rather meagerinformation, there has been a gen
29、eral indication,at least, for airplanes up until a few years ago,that the model spun with more outward sideslipthan did tile airplane. (See refs. 13 and 14.)This could possibly lead to optimistic tunnelresults for designs having their mass distributedProvided by IHSNot for ResaleNo reproduction or n
30、etworking permitted without license from IHS-,-,-8 TECHNICAL REPORT R-57-NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONchiefly along the wings but to pessimistic lunnelresults when the mass is distributed ehiefly alongthe fuselage. (See part IIA.) This factor isWen cognizance in predicting full-scale
31、 resultsflom tunnel tests.Tunnel technirque. A factor which may alsolead to differences in model and airplane resultsmay be classified as tunnel technique. The modelsare launched in a flat attitude wifl_ high rotationinto the spin tunnel in order to be assured ofobtaining any flat spin that may be p
32、ossible.Because of lhe high inertias of present-day de-signs, spinning lendeneies may be indicated onthe model which may not be readily obt.ainable, ormay not be obtainable al all, on the correspondingairplane because the same high inerias augmentingthe spin in the tunnel will tend to make il moredi
33、fficult for the airplane to increase its rate ofrotation up to lhat required for the spinningcondition. This can possibly make model re-sulls too conservative. IIowever, experience hasindicated that, even though airplane spin re-coveries sometimes appear to be better than thosepredieled by nan(tel r
34、esults, oftentimes a spinningcondition with poor recovery may be eventuallyobtained as a result of a violent maneuver, api(ch-np, a directional divergence, or even aninadverient asymmetric lderal Inca.lion of thecenter of gravily. In some ins(anees, because ofthe initial high angle of attack at whic
35、h a modelis launct,d into the spin tunne|, an autoroIativemomen due lo ttle nose may prewdl on flw modelbut may not occur on lhe airplane because itnever gets to a corresponding high angle of al tack.There is a possibility, also, lhat a Reynolds num-be, effect may be present on the model at theiniti
36、al high angle of ailack q.t which it. spins inthe tunnel because of launching relation, whichmay cause the autoroiaiive tendencies betweenmodel and airplane to differ. This possibility isconsidered in evalualing lunnel results. In addi-tion, because spins of present-day airplanes areoften very oscil
37、lalory in nature, primarily in rolland yaw, there is sometimes a tendency for theoscillations to resolve themselves into ano-spinning condition without movement of controls.lFn the spin tunnel, the oscillatory spins are oft.endiffieulL to obtain, either because of the tendencyto resolve into a no-sp
38、inning condition or becauseof space limitations. After many repeated at-telnpts, however, the spin can generally be main-tained and h,sted for ease or difficulty of recovery.It is not too surprising, therefore, that some-times a spin on an airplane corresponding to thatobtained on the model may not
39、be easily obtain-able. Eventually, however, possibly because ofsome fairly insignificant change in lhe airplane,which may have a critical effect on the spinningtendency, a spin may be obtained on the airplaneand, unless proper consideration has been given -this likelihood, the airphme may get into t
40、roubleand may even be lost in a spin.TECnYu_ueS FOR STraY OF INOPmNT Se_NBecause of the apparent inability of incorpo-rating into the airplane provision for insuringsatisfactory recovery from the developed spin,more attention has recently been given to theincipient spin. The incipient, spin is consi
41、deredto be different flom that of the developed spinin /hat the former is a transient ,notion extendingfloin some point after the stall to some point justbefore the spin becomes developed (equilibrium).When “rod why some designs enter the developedspin quickly and lhe ease or difl3eulty of prevenlin
42、gthe developed spin altogether are problems of_eat importance.Several years ago, a (.atapult. was built forincipient-spin studies (ref. 15) utilizing spin-tunnel models. Although results from this fqeilityhave been useful, the technique is inadequatebecause of space limitations. Currently, a tech-ni
43、que is being developed for studying the incipientspin by means of launehing radio-controlledmodels hom a helicopter. These models rangefrom _0 to _/scale in size. f current and futuredesigns are compromised too nmeh in providingadequate eonlrol fi)r termination of the developedspin, it becomes incre
44、asingly important to pre-vent the development of the spin. Recoveriesattempted during the incipient phase of the spinmay be more readily attainable than thoseattempted after the spin 1)ecomes fully developedbecause controls which are ineffective in the -developed spin, owing to attitudes, rotation,
45、andgyroscopic effects, may be effective for termini- -tion of the incipient spin.B. ANALYTICAL SPIN STUDIESDuring recent years, analytical investigationshave been initiated in which spin-entry, developed-spin, and spin-recovery motions of airplanes arestudied by calculating time histories of the!1Pr
46、ovided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-STATLS OF SPIN RESEARCH FOR RECENT AIRPLANE DESIGNS 9Jattitude, velocity, and acceleration variables ofthe motions through the use of static and rotaryaerodynamic data. and six-de_ee-of-freedom equa-tion
47、s of motion. It is expected that these investi-gations will augment the knowledge gained fromcustomary free-spinning dynamic-model tests andfull-scale-airplane spin tests and will aid in ob-taining a better understanding of these ofteninadvertent and sometin_es dangerous flight mo-tions. In referenc
48、es 16 and 17, calculationmethods were described and the results of someinitial step-by-step calculations were presented.More recently, calculations have been made on anelectronic analog computer of the recoverycharacteristics from a steady developed spin of anunswept-wing fighter-airplane configurat
49、ion asaffected by the application of various amounts ofconstant applied yawing moments, rolling nm-ments, or thrust force. Calculation methods androtary-balance aerodynamic data used in obtainingthe analog-computer results are presented anddiscussed. The results are presented as timehistories of some of the attitude and velocityvariables of the motions. Statements are maderegarding tire nature of the motions wh
