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1 UNCLASSIFIED?7 ied erv~i t-siiechnio Ial orfla DOCUIMENT SERVICE CENTER KNOTT'BUILDING, DAYTON, 2, OHIO gency -Chi document is the property of the United States Government. It is furnished for the duraticni of the contract and shall be returned when no longer required, or upon recall by ASTIA W0 tie!oliowing address: Armed Services Technical Information Agency, Docutmant Service Center, Knott Building, Dayton 2, Ohio. NOTICE: WHEN GOVERNAIENT OR OTHER DRAWINGS, SPECIFICATIONS OR OTHER DATA ýf " ; :E' FOR ANY PURPOSE OTHER THAN IN CONNECTION WITH A DEFINITELY RELATED GOVEEhN"AENT PROCUREMENT OPERATION, THE U. S. GOVERNMENT THEREBY INCU113 NO RE8F NSIBILITY, NOR ANlY OBLIGATION WHATSOEVER; AND THE FACT THAT THE GOVERNA,4ENT MAY HAVE FORMULATED, FURNISHED, OR IN ANY WAY SUPPLIED THE SAID DA. WINGS, SPECIFICATIONS, OR OTrER DATA IS NOT TO B REGARDED BY IMPLICATION OR OTHERWISE AS IN ANY MANNER LICENSING THE HOLDER OR ANY OTHER [;! "PERSON i I" OR N CORPORATION, LLA ", OR CONVEYING ANY,oS4 RIGHTS OR bu PERMISSION TO MANUFACTURE, =USE OR ;ELL ANY PATENTED INVENTION THAT MAY IN ANY WAY BE RELATED THERETO. L

2 LFC MEMORANDUM REPORT No JULY 1956 Aerodiynamic Propert~ies Of 60-MM Mortar Shell, T24 EUGENE D. BOYER OtPAPTMIENT OF THE ARMY PROJr=CT No. SSO3..O3-001 *ORDNANCE RESEARCH AND DEVELOPMENT PROJECT No. TB3-0108( BALLISTI1C RESEARCH LABORATORIES ABERDEEN PROVING GROUINDt MARYLAND

3 BALLESTIC RESEARCH LABORATORIES MEMORANDU4M REPORT NO JITLY 1956 AERODYNAMIC PROPERTIES OF 60-MM MORTAR SNELL, T24 Eugene D. Boyer Department of the Army Project No. 5B Ordnance Research and Development Project Kc. TB-_=Olr8 ABERDEEN PROVING GR0UN D, MARYLAND

4 TABLE OF CONTENTS Page A B... S TRRACT... 3 TABLE O1, SYMBOLS AND COEFFICIENTS... 4 INTRODUCTION EXPERIMETAL PROCEDURE... 5 EXPERIgnTAL RESULTS... 6 A. Drag B. Yawing Motion C. Roll APPENDICES APPENDIX A: Tables of Data Table 1 - Aerodynamic Data... 9 Table 2 - Roll Data APPENDIX B: Graphs and Photographs APPENDIX C: References DISTRIBUTION

5 BALLISTIC RESEARCH LABORATORIES MEMORA1NDUM REPORT NO EBoyer/rf Aberdeen Proving Ground, Md. July 1956 AERODYNAMIC PROPERTIES OF 60-MM MORTAR SHELL, T24 ABSTRACT The spin histories, drag, and yaw properties of the 60-mm T24 mortar shell are presented. These data were obtained from Transonic Range firings. I i ['I

6 TABLE OF SYMBOLS AND COEFFICIENTS A B cm axial moment of inertia transverse moment of inertia center of mass d- diameter M K D KM Mach number drag coefficient moment coefficient KM moment coefficient due to cross acceleration (Reference 5) Ký lift coefficient damping coefficient roll rate (deg./ft.) x 1,2 b yaw damping rates eine of the angle of yaw 2- mean squasred yaw K S2 K102 + K 20O2 + + e 10l + 20 '2 effective squared yaw for KM CL ro3.l moment derivative due to canted surface C L p P roll moment derivative due to rolling velocity density of air total velocity h U

7 INTRODUCTION In connection with a mortar project of the research division of the Bucid Company, Picatinny Arsenal requested that the Ballistic Research Laboratories study the aerodynamic properties, particularly roll, of the 60-mm T24 mortar shell. The shell was tested with three different fin assemblies: non-canted fins, fins with two degrees of cant on the after section, and fins with four degrees of cant on the after section (Figure 7a). The firings were conducted in the Transonic Range. This report is a brief account of the firings and the results obtained. EXPERIMENTAL PROCEDURE The shell were launched from a trigger-fi red 60-mm mortar tube mounted in a 105-nm howitzer field mount (Figure 7b). At normal velocities and the elevation angles necessary to fire through the Transonic Range instrumentation the morter shell would hit within the range building. Hence it was necessary to fire the program from within the range building and forego some of the instrumentation. For the shell to enter the instrumentation, it was necessary to start its flight approximately nine feet above the range floor. To obtain this height, the field carriage was loaded in the rear of a 2-1/2 ton shop truck (Figure 8) and the program fired from a point between the first two groups of 6 range stations. As a result only twenty of the twenty-five spark photographic stations could be utilized. Timing cables were rearranged to permit thirteen time-of-flight measurements to be taken. To determine the roll histories of the shell, sets of three yaw cards were placed at the beginning and end of the shadowgraphic instrumentation. The shell were equipped with two "pop-out" pins which remained -within the shell's contour during launching and emerged when the projectile entered free flight. The pins extended beyond the major diameter and cut the yaw, cards. projectile was determined. From these cuts the roll history of the To extend the roll measurements to longer ranges (1.800 feet) it was necessary to fire a few rounds outdoors. higher angle I-raj~etoeies requtirpd for the.jonver rareera y 'el-ld r]ot b. firnc from. inside the range building. The

8 Nineteen rounds were fired through the range and eleven outdoors. A-l of the rounds were fired at a nominal velocity of 500 fps. Twelve of the nineteen shell fired through the range had trajectories suitable for determining aerodynamic data. Roll data at 1800 feet were obtainable from only four of the eleven shell fired outside the range. A sketch of the shell and its physical measurements are given in Figure 6. EXPERIMENTAL RESULTS A. Drag The drag coefficient does not appear to be-noticeably affected by the presence of different fin cents. Any differences that may exist3 are well within the scatter of drag data expected from round to round variation with production shell. However, a definite variation of drag with yaw level is evient (Figure 1) and, fitting a least squares to KD-K + K 28 yields: D D. D6 K ý0= o K 2 = 2.1 _+ where 8 is in radians. All errors are standard errors. B. Yawing Motion The values of the yaw properties for each round are given in Table 1. As seen in Figures 2 and 3 the moment coefficient, K, and the lift cbefficient, K, are influenced by the magnitude of the yaw. These coefficients have been reduced to zero-yaw4 values by the ralationships: I where righting moment pd 3 5L + b U -U

9 K 2 and e is a function of the amplitude of the two yaw components and the rates as defined in the Table of Symbols and Coefficients. In Reference 4it is aho-w, Chat if non-linearities in aerodynamic forces ar(i moments 2 K20 are representable by cubics in yaw, then KM Vs. 5 e and KL vs. K10) + 2 form linear combinations. Fitting by least squares gives: * =I 'P- = K 1 = KL B2 when yaw is expressed in radians. The yaw damping coefficient, I - A was poorly determined due to the presence of emall asymmetries in the shell and no correlation with yaw was apparent. A value of.f - KlA = 8.0 seems representative of this shell. The amplitude of yaw damps fifty cycles of yaw, a distance of 300 feet. ]er cent in approximately two C. R6ll The roll data, as determined from yaw card measurements, are given in Table 2 and Figures 4 and 5. Slight inconsistencies in performance from round to round, as shown in Table 2, are probably due to minor fin misalignments and manufacturing variations in the cents of the trailing edges of the fins. Yaw card measurements for the shell with the uncanred fins indicated that the shcll were not spinning significantly. Tric e rounds were not inulided in fitting 1.

10 I The differential equation of motion of a rolling finned missile for a range trajectory is of the form': + C 022 The constants wore determined from fitting are: the yaw card measurements and 20 cant C = (l/ft) S2= (1/ft 2 ) f4o cant C 1 = (i/ft) 0 2 = (1/ft2 Nominally C1 should be the same for missiles differing only in fin cant and C2 should be proportional to the cant. The given C 's are essentially equal, within the signiticance of the determination, and in the same sense (on a per degree of cant basis) so are the C 2 _s. Average values would be: Cz 1 = (1/ft) C2 = (1/ft 2) per degree of cant. If one assumes the canted area of the fins to be one-tenth of the total fin area, where the fin area is approximately 2.07 square inches, the aerodyrnamic coefficientsi for the 4 degree canted fin are: * CL =3.0 P C L.21. EUGENE D. BOYER

11 (\J 0 n 00 'N.4 Co n 0 A 140 lk C4 N. K i Ni 'Il C 'Il Ni Nq 1q N'4 N N ~ A( ýa'~ 70cC CX 0 00 OH H 00 H N N )' 7 0C 0.0 '0) 0 0ON N C 01 UN N N 0 N 70 H o 0) 0 0, 0 0o 0, 0 d "0IC, IQ, 4. 0)-o ONd t-0 f O ' 'o cc 0 t -11 H 4 8 o N H~ 4Q 4 co HO)a t "o ohn N t"0-4 0)4 co1 '0 0417' 440 Co a) H 017) ý t-. co) COO 00.) ) 'o 0, -1 co r- 0' t- -t0 N 0 P o7 o7 o0 C)) C) )_ 0- v0 wr w1 N 9 u(i

12 TABIE 2 Roll Data (deg/ft) Distance Dowr Range (ft) Roll Rate For Various Rounds Fin Cant Field Firings o i.o 1, : Fin Cant Field Firings O

13 APPENDIX B Graphs and Photographs Figure 1 - Drag Coefficient vs. Mean Squared Yaw 2 Figure 2 - Moment Coefficient vs. 5 e 2 Kl2 2 Figure 5 - Lift Coefficient vs. K + K2 Figure 4 Roll Rate vs. Distance Down-Range, Fin-Cant 20 SFigure 5 - Roll Rate vs. Distance Down-Range, Fin-Cant 40 Figure 6 Sketch of Shell, 6 0-mm Mortar Shell 124 Figure 7a - Shell with Non-Canted Fins, 20 Canted Fins, 40 Canted Fins Figure 7b mm Mortar Tube Mounted in a 105-mm Howitzer Recoil System Figure 8 - Gun Mount Loaded on a 2-1/2 Ton Shop Truck iii

14 z z 00 S>2 z 9"0 "0 wg 2 - ""0 0q -. Q o.9

15 i Ii ZC 0 LL LLN z w ; 00 0

16 IL 0 LL n ev% (JD c;i~j

17 IL w zz V2 W w 0 CO0 IC)

18 0L z 4% 0 CD 2C Z' (U- <00 >.. Ij

19 CAF o o 00

20 IA PIGUE7:Se hnncne FICT~j'pEo 2a SelWtIomCantedFis F qs 2Cnted Fine, Mou qnted Fin sp Howitzer Recoil Sv~tem

21 Ij -, 64I I toi PI

22 APPENDIX C REFERENCES 1- Boz,R.ER Nicolaides, J.D., A Method of Determining Some Aerodynamic Coefficients from Supersonic Free BRL Report 711, November MacAllister, L.C., Comments On the Preliminary RedUction of Symmetric and Asymmetric Yaw Motions of Free Flight Range Models, BRLM Report 781, May MacAllister, L.C., Roschke, E.J., The Drag Properties of Several Winged and Finned Cone-Cylinder Models, BRLM Report 849, October Murphy, C.H.-, The Measurement of Non-Linear Forces and Moments by Means of Free Flight Tests, BRL Report 974, Murphy, C..1., Nicolaides, J.D., A Generalized Ballistic Force System. BRL Report 933, May Rogers, W.K., The Transonic Free Flight Range, BRL Report 841 9, February II 21

23 DISRTIBUZ[ON LIST No. of No. of C22iee Organization Coies n Chief of Ordnance 3 Commander Departmc-t of the ;c W Naval Ordnance Test Station Attn:sh RDUg - D.c China LJohe, California ORDBa Attn: Technical Library O edtx-ar Aoc t er ieclli etics S~Code Laboratory 'Washington , 1). C.Atn S ' Commander British a0 Joint Services MissionKnott A n S te N Washington 6, Eglin D. Air Ct Force Base Florida Attn: A s C i Attn: Mr. John Izzard, Reports Officer Director 180 K Streau, of rnw n Attn Armed 4 Se-rvices Canadian 2,c rmm Technical Army Staff Cne Information Agency W50 Massachusetts Avenue, NW Documents Service Center Nashington 8, D.GC. Knott Buddirpor 3 Chief, Bureau of Ordnance Dayton Attn: DSC-SD d, Ohio Department of the Na-vy Ashnttn: 2e, D.Ný"-aional Advisory Committee A0for Aeronautics Lewis Flight Propulsion S2 Commander Laboratory.. "Naval Proving Ground Cleveland Airp~ort SDah~lgren, Virginia Cleveland, Ohio 2 CmnaderAhtn: F. K. Moore 2 Commander Naval Ordnance Laboratory I Commanding ""White General Oak Redstone Arsenal Silver Spring 19, Maryland Huntsville, Alab-a Attn- Mr. Nestinger Attn: Dr. may Tecicalua 1 Superintendent ldbrary 1 S rcommanding General Picatinny Arsenal Naval Postgraduate School D,'0,. New Jersey Monterey, California Attn: Saniel Felt:an Aoqnmunition LahT. Naval Air Missile Test Center Vf;wv.. JgGeea Point Magu., California Frankford Arsenal Phiie hin 57,7 P-,y vsnia Commanding Officer and Director Attn: Reports Group David W. Taylor Model Basin Washington 7, D. C. Attn: Aerodz.xnamlcs Laboratory 25

24 I I DISTRIBUTION LIST No. of Copies Organization Directori JPH Ord Corps Installatlon 800 Oak Grove Drive Department of Lhe Army Pasadena, California Attn.. Mr. Irl E. Newlan, Reports Group Commanding Officer Chemical Corps Chemical and Radiological Lab. Army Chemical Center, Maryland 1 ~Direc tor Operations Resea.-ch Office 7100 Connecticut Avenue Chevy Chase, MaryId Washington 15, D. C. The Budd Company 2450 Hunting Park Avenue Philadelphia 30ý, Penn sylvania Attn.: Mr. Earl A. Zettlemoyer Product Reseach Division