NASA NACA-TR-1268-1956 Theoretical calculations of the pressure forces and moments at supersonic speeds due to various lateral motions acting on thin isolated vertical tails《由于薄且单独.pdf
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1、REPORT 1268THEORETICAL CALCULATIONS OF THE PRESSURES, FORCES, AND MOMENTS ATSUPERSONIC SPEEDS DUE TO VARIOUS LATERAL MOTIONS ACTINGON THIN ISOLATED VERTICAL TAILS By EENNBTH MARQOLIS and PEECYJ. BorwmrrSUMMARYvehI poteniiab, pre8 cotangent ofsweepback angle of leading edge (see fig. 1)=1dH%7Bm*(Bm)=
2、mm=aE (k)E(k) complete elliptic integral of second liiud withmodulus JTJ2h-(1-H) sid n dnoK (k) complete elliptic integral of fist kind withmodulus ,JT/ dn0 J1(1H) sinnr, u, CO arbitrary constants (G=uBm)W+k)K(k)+( l4c+k)E(k)“= (z.-k) (12k)E(k)+k( l+k)K(k)E(k) kK(k)2(l+)(l +k)E(k) 2kK(k)“=- 2(2-k)(1
3、 2 simple charts are presented which permitrapid estimation of the 12 stability derivative for givenvdues of aspect ratio and Mach number. Tabulationof the derivatives for subsonic-edge trianghr tails withtrailing-edge sweep are also presented.Three systems of body axes are employed in the presentre
4、port. For plan-form integrations and in the derivationand presentation of velocity potentials and pressures, theconventional analysis system shown in figure 2 (a) is utilized.In order to maintain the usual stability system of positiveforces and moments, the axes systems shown in figures 2(b) and 2 (
5、c) are used in formulating the stabili derivatives.A table of transformation formulas is provided which enablesthe stability derivatives, presented herein with reference toa center of gravity (origin) located at the leading edge of theroot chord (fig. 2(b), to be obtained with reference to an arbitr
6、ary center-of-gravity lomtion (fig. 2 (c).BASICCONSIDERATIONSThe calculation of forces acting on the vertical tail essen-tially requires a knowledge of the distribution of the pressuredifference between the two sides of the tail surface. Thispressure-difference distribution is expressible in terms o
7、f theperturbation-velocity-potential d.iiference or “potential jumpacross the surface” Aq by means of the linearized relationship(1)Inasmuch as for the present investigation thin isolated tailsurfaces are considered and thus no induced effects arepresent from any neighboring surface, the perturbatio
8、nvelocity potentials on the two sides of the tail are equal inmagnitude but are of opposite sign. Equation (1) may thenberemittenin terms of the perturbation velocity potential p asfollows:(qwhere q is evaluated on the positive y-side of the tail surface.The basic problem, then, is to find for each
9、motion underconsideration the perturbation-velocity-potential functionp for the various tail regional areas formed either by plan-form or plan-form and Mach line boundaries. (See, forexample, the sketch given in table I.)For time-independent motions, such as steady rolling,steady yawing, and constan
10、t sideslip, the potential functionsare” of course independent of time (i. e., the last term ineqs. (1) and (2) vanishes) and may be determined for thesubsonic-leading-edge cases by the doubletdistributionmethod of references 14 and 15. The details of the methodand its application are given in the ap
11、pendixes. The super-sonic-leading edge ccdgumtions are analyzed by the well-known source-distribution method utilizing the area-can-cellation-Mach line reflection technique of reference 16.The mathematical details are not presented herein, becauseit is felt that previous papers dealing with wing pro
12、blems(e. g., refs. 17 to 20) have applied the basic method in sufli-cient detail. The main difhwence to be noted is that theroot chord of the isolakd vertical tail is, in effect, anotherfree subsonic edge similar to the tip chord and must betreated accordingly. Actually, tail regions I and III (refe
13、rto the sketch in table I) are not affected by the additional.Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-d388 REPORT 1268NATIONAL ADVISORY COMMITTEE FOR AERONAUTICStip, and wing results in these regions for constant angleof attack (ref. 20), st
14、eady rolling (ref. 20), and steady pitch-ing (ref. 18) are applicable to constant sideslip, steadyrolling, and steady yawing motions, respectively, for theverticid tail, provided appropriate changes in coordinatesare introduced and the proper sign convention is maintained.The timedependent motion co
15、nsidered in the presentreport, that is, constant lateral acceleration, can be analyzedin a manner analogous to that used for a wing surface under-going constant vertical acceleration (e. g., refs. 21 to 23).By following this procedure, the basic expressions for theperturbation veloci potential and p
16、ressure coefficient(evaluated at time t=O) may be derived as follows:(3)=-E-(+%dAp( (9 +% P $=+ and thus the first integrationwith respect to z in equations (5) and (7) yields p; hence,equations (5) and (7), when applied to steady motions, reduceto essentially a single integrationfunction.involving
17、the potentialThe nondimensional force and moment coefficients *andcorresponding stability derivatives are directly obtainablefrom the definitions given in the list of symbols. I?orexample,l%(YLv J r-loInasmuch as the various pressure coefficients are linear withreference to their respective angular
18、velociticw, attitude, oracceleration (i. e., linear in p, r, P, or ), the partial clerivn-tive in the preceding example may be replaced by the stability derivatives due to rBu(BmBu) tanh-270 (1ll%qfl d(Bu) (C5)It might be mentioned at this point that the integrands of expressions (C-4) and (C5) are
19、finite and continuous over the intervalO to Bm and therefore must yield a iinite quantity -when integrated.The integration of expression (C4) by parts givmIntegration of expression (C5) by parts givesProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.
20、.396 REPORT 1268NATIONALCombining expressions (C6) and (C7) results inADVISORY COMMIITE.E FOR AERONAUTICS(C8)The fit term of equation (C8), w-hen evaluated at the limits, is either zero or iniinity. The integrand of J, aa ma noted,is finite over the whole interval; tharefore, infinities introduced a
21、s a result of parts integrations must, in the end, canccdthemselves.The second term of equation (C8) is an elementary integration which when evaluated (with infinities neglected) yields(T 2r+4Z3TBm5GBm 4Z5uBm+2r+3rBm - .HGrn ) (C9)It is now convenient in integrating the third term in equation (C8) t
22、o introduce the variable substitutionso that Bm and k are related by2km=l+h?The third term in equation (C8) when transformed by equation (C1O) maybe written in the formwhere(Clo)(011)(C12)I,= J kT(I+k)4(+)dx_, lI,= J k(7-+dF)F(#)d#-tI,= J :, (Ui?lj) (*)d*The integrals I, 15, and 1, are elementary an
23、d may be determined by an integration by parts. If the multiplicative factorProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-THEORETICAL AERODYNAMICS OF THIN ISOLATED VERTICAL TAILS AT SUPERSONIC SPEEDS 397before the summation sign in equation (C12) i
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