Buckets:
| {"citation_id": "19930082618", "source_url": "https://ntrs.nasa.gov/api/citations/19930082618/downloads/19930082618.pdf", "page_number": 77, "total_pages": 78, "image_filename": "19930082618_p77.jpg", "text": "NACA TN 1945\n75\n\nMaximum section lift coefficient, $c_{l,max}$\n\n$\\circ$ NACA 0012\n$\\square$ NACA 4412\n$\\diamond$ NACA 4415\n$\\triangle$ NACA 23012\n$\\nabla$ NACA 23015\n\nAirfoils with .20c split\nflaps deflected 60°\n\nPlain airfoils\n\nFlagged symbols and broken lines denote airfoils\nwith standard leading-edge roughness\n\nNACA\n\nReynolds number, R\n\nFigure 22.— Variation with Reynolds number of maximum section lift\ncoefficient for three NACA 4-digit-series airfoils and two\nNACA 5-digit-series airfoils.\n\nNACA-Langley - 10-7-49 - 800", "timestamp": "2026-07-22T06:01:48.362228+00:00"} | |
| {"citation_id": "19930091993", "source_url": "https://ntrs.nasa.gov/api/citations/19930091993/downloads/19930091993.pdf", "page_number": 20, "total_pages": 21, "image_filename": "19930091993_p20.jpg", "text": "```markdown\n# APPENDIX\n\n## SYMBOLS\n\nThe following symbols are used in this report:\n\n| Symbol | Definition |\n| :--- | :--- |\n| $F_n(T_{T,2})$ | clearance correction factor for turbine torque (or moment) |\n| $F_g(T_{T,2})$ | clearance correction factor for gas mass flow |\n| $f$ | fuel-air ratio |\n| $H$ | enthalpy, ft-poundal/lb |\n| $H_f$ | enthalpy of incoming fuel, ft-poundal/lb |\n| $h$ | heating value of fuel, ft-poundal/lb |\n| $n$ | rotative speed of engine, rps |\n| $P_a$ | auxiliary power consumption such as bearing loss, ft-poundal/sec |\n| $p$ | gas pressure, lb/sq ft |\n| $R$ | gas constant, ft-poundal/(lb)($^\\circ$R) |\n| $T$ | gas temperature, $^\\circ$R |\n| $W$ | mass flow of gas, lb/sec |\n| $W_g'$ | mass flow of gas through turbine corrected for turbine-blade-tip leakage, lb/sec |\n| $\\gamma$ | ratio of specific heats of gas, $c_p/c_v$ |\n| $\\Delta H_c$ | stagnation enthalpy rise of air in compressor, $H_{T,2}-H_{T,1}$, ft-poundal/lb |\n| $\\Delta H_p$ | stagnation enthalpy drop of gas in power turbine, ft-poundal/lb |\n| $\\Delta H_{s,c}$ | isentropic rise in stagnation enthalpy of gas in compressor, ft-poundal/lb |\n| $\\Delta H_{s,t}$ | isentropic drop in stagnation enthalpy of gas in turbine, ft-poundal/lb |\n| $\\Delta H_t$ | stagnation enthalpy drop of gas in turbine, ft-poundal/lb |\n| $\\Delta H_t'$ | stagnation enthalpy drop of gas in turbine corrected for turbine blade-tip leakage, ft-poundal/lb |\n| $\\eta$ | combustion efficiency |\n| $\\theta$ | ratio of square of sonic speed of gas to square of sonic speed for normal air |\n| $\\rho$ | gas density, lb/cu ft |\n| $\\sigma$ | ratio of gas density to normal air density, $\\rho/\\rho_{st}$ |\n\n**Subscripts:**\n0 free-stream\n1 compressor inlet\n2 compressor outlet\n3 turbine inlet\n4 turbine outlet\nst standard air\nT stagnation or total\n\n## REFERENCES\n\n1. Sinnette, John T., Jr., Schey, Oscar W., and King, J. Austin: Performance of NACA Eight-Stage Axial-Flow Compressor Designed on the Basis of Airfoil Theory. NACA Rep. 758, 1943.\n2. Sinnette, John T., Jr., and Voss, William J.: Extension of Useful Operating Range of Axial-Flow Compressors by Use of Adjustable Stator Blades. NACA Rep. 915, 1948.\n3. King, J. Austin, and Regan, Owen W.: Performance of NACA Eight-Stage Axial-Flow Compressor at Simulated Altitudes. NACA ACR E4I21, 1944.\n4. Goldstein, Arthur W.: Analysis of Performance of Jet Engine from Characteristics of Components. I—Aerodynamic and Matching Characteristics of Turbine Component Determined with Cold Air. NACA Rep. 878, 1947.\n5. Keenan, Joseph H., and Kaye, Joseph: Thermodynamic Properties of Air. John Wiley & Sons, Inc., 1945.\n6. Pinkel, Benjamin, and Turner, L. Richard: Thermodynamic Data for the Computation of the Performance of Exhaust-Gas Turbines. NACA ARR 4B25, 1944.\n7. Stodola, A.: Steam and Gas Turbines. Vol. II. McGraw-Hill Book Co., Inc., 1927, p. 271. (Reprinted, Peter Smith (New York), 1945.)\n8. Pinkel, I. Irving, and Shames, Harold: Analysis of Jet-Propulsion Engine Combustion-Chamber Pressure Losses. NACA Rep. 880, 1947.\n9. McLellan, Charles H., and Nichols, Mark R.: An Investigation of Diffuser-Resistance Combinations in Duct Systems. NACA ARR, Feb. 1942.\n\n16\n\nU. S. GOVERNMENT PRINTING OFFICE: 1950\n```", "timestamp": "2026-07-22T06:01:49.138791+00:00"} | |
| {"citation_id": "19930086061", "source_url": "https://ntrs.nasa.gov/api/citations/19930086061/downloads/19930086061.pdf", "page_number": 34, "total_pages": 114, "image_filename": "19930086061_p34.jpg", "text": "[No readable text detected]", "timestamp": "2026-07-22T06:01:50.680015+00:00"} | |
| {"citation_id": "19930082511", "source_url": "https://ntrs.nasa.gov/api/citations/19930082511/downloads/19930082511.pdf", "page_number": 94, "total_pages": 99, "image_filename": "19930082511_p94.jpg", "text": "92\nNACA TN No. 1826\n\n<!-- Image (101, 236, 740, 781) -->\n\nDistance from entrance, $\\xi$, units of tunnel height\n\nFigure 22.- Tunnel-induced vertical velocity $v$ on axis of symmetrical two-dimensional closed-open-closed tunnel having additional velocities of $-u_b$ and $u_b$ on the upper and lower free boundaries, respectively. Length of open section is 1.5 times tunnel height.", "timestamp": "2026-07-22T06:01:52.430301+00:00"} | |
| {"citation_id": "19930082613", "source_url": "https://ntrs.nasa.gov/api/citations/19930082613/downloads/19930082613.pdf", "page_number": 5, "total_pages": 46, "image_filename": "19930082613_p5.jpg", "text": "4\nNACA TN 1938\n\nMicrospecimens from the as-fabricated type-A liner and from a\ntype-B liner, run for 16 hours and 40 minutes, were also studied.\nThe specimens from the type-A liner were examined to determine the\ninitial condition of punched edges prior to use, and the specimens\nfrom the type-B liner were examined to determine whether the cracks\nbegan in an intercrystalline or transcrystalline manner.\n\nThe samples were examined with a research metallograph and\nseveral auxiliary measuring eyepieces, such as a filar micrometer\neyepiece that could measure distances down to a few hundred thou-\nsandths of an inch, and a grain-size measuring eyepiece.\n\nProduction of thermal gradients in type-B liner. - An acetylene\nflame was used to produce hot zones and temperature gradients in a\nliner similar to those formed in the liners during engine operation.\nThe oxide patterns formed on the liners run for almost 67 hours\nwere used to indicate the temperature patterns that should be pro-\nduced with the acetylene flame. In order to determine whether\nfailures similar to those found in liners could be reproduced in\nshort periods of time by artificially creating temperature gradients,\nthe following experiments were made:\n\n1. A thermal gradient was first produced by heating a louver\nflap and the surrounding metal for 1 minute to a maximum temperature\nof approximately 1700° F and cooling the portion immediately down-\nstream of the louver with an air blast. The temperatures were esti-\nmated from visual observation and the area was examined for buckling\nand cracking.\n\n2. The zone previously heated was then alternately heated and\ncooled 30 times and again examined.\n\n3. The upstream portion of the louver in the same zone was then\nheated to a maximum temperature of approximately 1900° F and the\nentire downstream portion was air-cooled. This procedure was followed\ntwice, the time of heating in each case being about 2 minutes.\n\n4. Several louver flaps were then alternately heated from the\ninside of the liner to about 1600° F and air-cooled. Motion of the\nflaps during the thermal cycle was observed.", "timestamp": "2026-07-22T06:01:55.982622+00:00"} | |
| {"citation_id": "19930082472", "source_url": "https://ntrs.nasa.gov/api/citations/19930082472/downloads/19930082472.pdf", "page_number": 29, "total_pages": 34, "image_filename": "19930082472_p29.jpg", "text": "NACA TN No. 1791\n27\n\nUnflagged symbols indicate\nupper surface.\nFlagged symbols indicate\nlower surface.\n\nSpanwise\nstation, 2y/b\n20.9%\n28.1%\n41.7%\n57.4%\n71.4%\n85.0%\n92.5%\n96.2%\n\nPressure coefficient, P\n1.2\n.8\n.4\n0\n.4\n.8\n\nChordwise station, x/c\n4\n6\n8\n10\n\nNACA\n\nFigure 5—Continued.\n(f) $\\alpha=16.6^\\circ$", "timestamp": "2026-07-22T06:01:56.559547+00:00"} | |
| {"citation_id": "19930086076", "source_url": "https://ntrs.nasa.gov/api/citations/19930086076/downloads/19930086076.pdf", "page_number": 40, "total_pages": 50, "image_filename": "19930086076_p40.jpg", "text": "[No readable text detected]", "timestamp": "2026-07-22T06:01:58.403303+00:00"} | |
| {"citation_id": "19930082646", "source_url": "https://ntrs.nasa.gov/api/citations/19930082646/downloads/19930082646.pdf", "page_number": 4, "total_pages": 37, "image_filename": "19930082646_p4.jpg", "text": "```markdown\nNACA TN 1980\n3\n\nDESCRIPTION OF MODEL\n\nThe model with the basic length-beam ratio of 15 was described in references 3 and 5. The general arrangement of the flying boat with the warped forebody and extended afterbody (Langley tank model 224J) is shown in figure 1. Hull lines of the model are presented in figure 2. The forebody of this model was modified by progressively increasing the dead rise from the step forward in the manner described in reference 1, thereby eliminating the customary straight buttocks on the forebody planing bottom just forward of the step. The afterbody length was increased from 6.37 to 9.24 beams as described in reference 2, the angle of afterbody keel remaining the same. The depth of step of 24 percent of the beam was the same as that used for tests of the basic model with the extended afterbody. The wing and tail were the same as those used in the tests of the hull having a basic length-beam ratio of 15.\n\nAPPARATUS AND PROCEDURES\n\nThe description of Langley tank no. 1 is presented in reference 6. The setup of the model and towing gear is shown in figure 3. The apparatus and procedures were identical to those described in reference 2. In all tests the model was free in trim and rise but restrained in roll and yaw.\n\nThe hydrodynamic qualities determined were the trim limits of stability, the range of center-of-gravity positions for satisfactory take-off stability, smooth-water landing stability, bow-spray characteristics during take-off, tail-spray characteristics during landings, propeller-spray characteristics while taxiing in waves, and impact accelerations and landing behavior in rough water.\n\nThe hydrodynamic qualities were all determined at a design gross load corresponding to 75,000 pounds except for the spray investigation in which gross loads from 75,000 to 95,000 pounds were included. The flaps were deflected $20^\\circ$ for all the hydrodynamic tests. With the exception of the landing tests, the hydrodynamic qualities were determined with full thrust. The landings in smooth water were made with approximately half thrust. In rough water the thrust was set so that the model was self-propelled during most of the landing run-out. Landing and spray tests were made with the center of gravity at 32 percent mean aerodynamic chord. The results have been converted to full-size units and all data with the exception of table I are presented as full-size values.\n```", "timestamp": "2026-07-22T06:01:59.760562+00:00"} | |
| {"citation_id": "19930093789", "source_url": "https://ntrs.nasa.gov/api/citations/19930093789/downloads/19930093789.pdf", "page_number": 26, "total_pages": 29, "image_filename": "19930093789_p26.jpg", "text": "```markdown\n1031\n\nCONFIDENTIAL\n\nEquivalent turbine shaft work, $E(\\omega_0/a_1)^2$, Btu/lb\n\nEquivalent mean blade speed $U(a_0/a_1)^2$, ft/sec\n\nBrake efficiency,\n\nTotal-pressure ratio, $p_1^1/p_3^1$\n\nEquivalent mean blade speed/equivalent weight flow, $U_0/\\dot{w}\\omega_0$, ft/lb\n\nFigure 12. - Over-all performance chart with 0°-cone-angle stator and labyrinth shroud (configuration 2).\n\nNACA RM No. E8121\n\nCONFIDENTIAL\n\n25\n\n```", "timestamp": "2026-07-22T06:02:00.846082+00:00"} | |
| {"citation_id": "19930093769", "source_url": "https://ntrs.nasa.gov/api/citations/19930093769/downloads/19930093769.pdf", "page_number": 22, "total_pages": 39, "image_filename": "19930093769_p22.jpg", "text": "NACA RM No. E8L10a\nCONFIDENTIAL\n21\n\nCorrected net thrust, lb\nFuel\n$\\Delta$ AN-F-58\n$\\square$ Gasoline\n\n(a) Altitude, 5000 feet; flight Mach number, 0.\n\nCorrected engine speed, rpm\n(b) Altitude, 20,000 feet; flight Mach number, 0.60.\n\nFigure 4. - Comparison of corrected net thrust for AN-F-58 fuel and gasoline at various altitudes and flight Mach numbers.\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:02:05.338596+00:00"} | |
| {"citation_id": "19930082566", "source_url": "https://ntrs.nasa.gov/api/citations/19930082566/downloads/19930082566.pdf", "page_number": 8, "total_pages": 44, "image_filename": "19930082566_p8.jpg", "text": "6\nNACA TN No. 1889\n\nload by means of an eccentric E1. The eccentric E1 is attached to a\ngear G2 which is driven by a pinion G1 and operated by a 3-horsepower,\n3600-rpm, alternating-current motor T (fig. 7). A gear reduction\nof 1 to 10 produces about 300 fluctuations of stress per minute at\nthe specimen. This low rate of stress fluctuation was necessary to\neliminate possible errors due to interference of pressure waves\nproduced by the successive application of internal pressure.\n\nThe internal oil pressure is applied to the specimen by means of\nthe piston in a Bosch pump I. The pump I is actuated by a plunger\nand connecting-rod system attached to a driving eccentric E2 (fig. 8).\nThe eccentric E2 is adjustable with respect to throw and phase angle\nbetween the two eccentrics E1 and E2 which are mounted on the same\nshaft. The pressure obtained in the specimen S is raised by increasing\nthe throw of the eccentric and, consequently, the stroke of the piston.\nA steel cylindrical plug, with dimensions slightly less than the inner\ndimensions of the specimen, is inserted in the specimen to reduce the\ntotal volume of fluid in the pressure system and so permit higher\npressure. To provide against drop in pressure caused by possible oil\nleakage, an accumulator A with a check valve C (fig. 10) is connected\nto the specimen. The accumulator A is a standard aircraft-type\naccumulator in which air is used as the pressure-maintaining medium.\n\nA revolution counter U is used to record the number of stress\nfluctuations to fracture. The motor is stopped by a microswitch when\nthe specimen is fractured. For axial tension without internal pressure\na microswitch is mounted on the lever K so that, when the specimen\nfractures, the yoke Y below the specimen rotates and operates the\nmicroswitch which stops the motor. For tests in which internal pressure\nis used, fracture of the specimen causes a drop in pressure, which\nreleases the plunger in the valve P. This operates the microswitch M\nwhich in turn stops the motor.\n\nThe axial load is measured by a 10,000-pound dynamometer N (fig. 9)\nwhich transmits the load from the eccentric E1 to the lever. A threaded\nturn-buckle unit between the eccentric and the dynamometer allows the\nadjustment of the minimum axial load. The lever with a 4-to-1 ratio\napplies the load to the specimen. The specimen is held between two\nspherical seats to insure axiality of loading.\n\nThe maximum and minimum pressures are measured by Bourdon gages H\nand L, respectively. The gages are connected to the piping with\nspecially designed check valves so that the pointers of the gages\ndo not fluctuate, but move only if there is a change in the values of\nthe maximum or minimum pressures. In this way the gage mechanisms\nare not subjected to fluctuating stresses.", "timestamp": "2026-07-22T06:02:09.330956+00:00"} | |
| {"citation_id": "19930086073", "source_url": "https://ntrs.nasa.gov/api/citations/19930086073/downloads/19930086073.pdf", "page_number": 38, "total_pages": 98, "image_filename": "19930086073_p38.jpg", "text": "36\n\nLift coefficient, $C_L$\n\nRolling-moment coefficient, $C_l$\n\nYawing-moment coefficient, $C_n$\n\nSide-force coefficient, $C_Y$\n\nAngle of sideslip, $\\beta$, deg\n$\\circ$ 0.0\n$\\square$ 12.1\n\n(d) $C_L$ vs $C_l$, $C_n$ and $C_Y$.\n\nFigure 6.— Concluded.\n\nNACA RM A59E04", "timestamp": "2026-07-22T06:02:10.250041+00:00"} | |
| {"citation_id": "19930085880", "source_url": "https://ntrs.nasa.gov/api/citations/19930085880/downloads/19930085880.pdf", "page_number": 71, "total_pages": 96, "image_filename": "19930085880_p71.jpg", "text": "NACA RM No. L9C03\n69\n\nTrimming moment, lb-ft\nSpeed (fps)\nWetted area, sq ft\n(e) $\\tau = 20^\\circ$.\nFigure 20.- Concluded.\nNACA", "timestamp": "2026-07-22T06:02:11.732297+00:00"} | |
| {"citation_id": "19930082483", "source_url": "https://ntrs.nasa.gov/api/citations/19930082483/downloads/19930082483.pdf", "page_number": 21, "total_pages": 78, "image_filename": "19930082483_p21.jpg", "text": "NACA TN No. 1807\n\ntotal-pressure ratio, and rotor speed. With the inlet total pressure set and maintained constant, the rotor speed was varied over the entire range for each pressure ratio. This procedure was repeated for each of the range-of-inlet pressure runs. The following table gives the range of performance investigation:\n\n| Gas admission (deg) | Total-pressure ratio | Inlet total pressure (in. Hg abs.) | Corrected rotor speed, rpm<sup>a</sup> |\n|---------------------|----------------------|------------------------------------|----------------------------------------|\n| | | | Minimum | Maximum |\n| 360 | 1.50 | 20 | 3391 | <sup>b</sup>9,227 |\n| | | 30 | 3410 | 12,941 |\n| | | 40 | 3354 | 12,925 |\n| | | 45 | 3377 | 12,685 |\n| | 2.00 | 20 | 3484 | 13,128 |\n| | | 30 | 3382 | 13,036 |\n| | | 40 | 3611 | 13,100 |\n| | | 45 | 3534 | 12,979 |\n| | 2.40 | 20 | 3463 | 13,157 |\n| | | 30 | 3444 | 13,643 |\n| | | 40 | 5292 | 13,304 |\n| | | 45 | 3562 | 12,905 |\n| 120 | 1.50 | 20 | 3427 | <sup>b</sup>8,921 |\n| | | 30 | 3431 | <sup>b</sup>10,239 |\n| | | 45 | 3411 | <sup>b</sup>10,749 |\n| | 2.00 | 20 | <sup>c</sup>3450 | <sup>b</sup>10,493 |\n| | | 30 | 3412 | <sup>b</sup>11,034 |\n| | | 45 | 3414 | 12,560 |\n| | 2.40 | 20 | 3397 | <sup>b</sup>10,675 |\n| | | 30 | 3436 | 12,185 |\n| | | 45 | 3445 | 12,620 |\n| 180 | 2.00 | 45 | 3394 | 12,134 |\n\n<sup>a</sup>Tip speed in feet per second equals rpm times 0.0704.\n\n<sup>b</sup>Speed limited by minimum dynamometer drag.\n\n<sup>c</sup>Some scatter in data.\n\nLosses\n\nDisk-spread friction and blade windage. - Selection of the working equations for the disk-friction and blade-windage losses was made on the basis of a comparison of the values for these losses as obtained by representative formulas with actual loss data on a smaller unit.", "timestamp": "2026-07-22T06:02:13.563239+00:00"} | |
| {"citation_id": "19930082618", "source_url": "https://ntrs.nasa.gov/api/citations/19930082618/downloads/19930082618.pdf", "page_number": 78, "total_pages": 78, "image_filename": "19930082618_p78.jpg", "text": "[No readable text detected]", "timestamp": "2026-07-22T06:02:16.228816+00:00"} | |
| {"citation_id": "19930085962", "source_url": "https://ntrs.nasa.gov/api/citations/19930085962/downloads/19930085962.pdf", "page_number": 51, "total_pages": 51, "image_filename": "19930085962_p51.jpg", "text": "50\nCONFIDENTIAL\nNACA RM A9E05\n\n$C_{L_\\alpha}$\nand\n$C_{L_\\delta}^*$\n\n$C_{L_\\alpha}$\n$C_{L_\\delta}^*$\n\n$\\alpha_\\delta$\n\nMach number, M\n\nFigure 15.—Variation of lift parameters $C_{L_\\alpha}$, $C_{L_\\delta}^*$, and $\\alpha_\\delta$ with Mach number.\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:02:17.342731+00:00"} | |
| {"citation_id": "19930082592", "source_url": "https://ntrs.nasa.gov/api/citations/19930082592/downloads/19930082592.pdf", "page_number": 7, "total_pages": 50, "image_filename": "19930082592_p7.jpg", "text": "6\nNACA TN 1914\n\nformed is protective and inhibits further oxidation (reference 3).\nThe effect of increasing the percentage of the metallic component is\nnot as harmful to the oxidation resistance of the cobalt ceramals as\nit is to either the molybdenum or the tungsten ceramals.\n\nThe oxidation-rate constants for the cobalt ceramals appear to\nbe practically independent of temperature at the three temperatures\nconsidered (fig. 7). At 1625° F, the oxidation-rate constant of the\n30-percent-cobalt ceramal was found to be higher than for any of the\nother temperature-composition combinations.\n\nExamination of Oxidation Zone\n\nThe phenomenon of surface oxidation is dependent upon the rate at\nwhich oxygen for the oxidation reaction reaches the oxidation inter-\nface. If the oxide formed offers no resistance to diffusion of the\noxygen, the thickness of the coating will increase linearly with\ntime. If the oxide formed is tightly adherent and resistant to the\ndiffusion of oxygen, the rate of oxidation will decrease as the thick-\nness of the oxide increases. If the oxide formed is volatile at the\noxidation temperature, it will leave the surface and afford no pro-\ntection; whereas at the same temperature another oxide may be close\nenough to the melting point to sinter and form a very dense protec-\ntive coating. Another factor important in determining whether or not\nan oxide will have protective properties is its specific molecular\nvolume. The specific molecular volume is defined as the volume of\n1 gram mole of solid at room temperature. The oxides that have a\nspecific molecular volume slightly greater than the unoxidized metal\nwill form dense protective coatings (reference 3). If the specific\nmolecular volume of the oxide is large compared with that of the\nunoxidized material, however, the oxide will break away at the\noxidation interface and will have no protective value.\n\nExamination revealed that the oxide coatings of the molybdenum\nceramals were rather chalky and porous. The oxidation penetration\ninto all the molybdenum ceramals was along an interface parallel to\nthe surface at all temperatures investigated. The oxides formed on\nthe tungsten ceramals were somewhat more adherent and were harder\nto remove by grinding than the oxides formed on the molybdenum\nceramals. With the exception of the 20- and 30-percent-tungsten\nceramals at 1625° and 1785° F, the oxidation penetration of the\ntungsten ceramals moved along linear fronts. Oxidation penetration\ntook place along grain boundaries in the excepted cases with the\ngrain-boundary penetration very slight at 1625° F as compared with\nthat at 1785° F.", "timestamp": "2026-07-22T06:02:19.928514+00:00"} | |
| {"citation_id": "19930082472", "source_url": "https://ntrs.nasa.gov/api/citations/19930082472/downloads/19930082472.pdf", "page_number": 30, "total_pages": 34, "image_filename": "19930082472_p30.jpg", "text": "28\nNACA TN No. 1797\n\nUnflagged symbols indicate\nupper surface.\nFlagged symbols indicate\nlower surface.\n\nPressure coefficient, $P$\n-16\n-12\n-.8\n-.4\n0\n.4\n.8\n\nChordwise station, $x/c$\n.2\n.6\n.8\n1.0\n\nSpanwise\nstation, $2y/b$\n20.9%\n28.1%\n41.7%\n57.4%\n71.4%\n85.0%\n92.5%\n96.2%\n\n(g) $\\alpha=20.7^\\circ$\n\nFigure 5—Continued.", "timestamp": "2026-07-22T06:02:21.962960+00:00"} | |
| {"citation_id": "19930082511", "source_url": "https://ntrs.nasa.gov/api/citations/19930082511/downloads/19930082511.pdf", "page_number": 95, "total_pages": 99, "image_filename": "19930082511_p95.jpg", "text": "NACA TN No. 1826\n93\n\n[Figure: Diagram of a closed-open-closed tunnel with coordinate systems labeled $\\xi$, $\\eta$, $\\rho$, $\\theta$, $a$, and $b$]\n\nNACA\n\nFigure 23-Closed-open-closed tunnel, showing\ncoordinate systems.", "timestamp": "2026-07-22T06:02:22.862738+00:00"} | |
| {"citation_id": "19930082546", "source_url": "https://ntrs.nasa.gov/api/citations/19930082546/downloads/19930082546.pdf", "page_number": 12, "total_pages": 65, "image_filename": "19930082546_p12.jpg", "text": "NACA TN No. 1870\n\nPressure amplitudes (rms) of the first four harmonics were measured with a Hewlett-Packard harmonic wave analyzer adjusted to a band width of 100 cycles per second.\n\nFlat vertical and circular fuselage walls were simulated and their effects on the magnitudes of pressures in the plane of the walls were evaluated. Figures 5(a) and 5(b) show construction of the flat vertical wall and figure 5(c) shows corresponding details of the circular wall. These walls were supported in such a way that the natural frequency of each structure as a unit was below the frequency range of the oscillating pressures to be measured. As first designed the surfaces of both walls vibrated locally when excited by the propeller frequencies. These local (panel) vibrations were reduced in both cases to a low value by heavy longitudinal reinforcement. By this method panel resonances were removed from the frequency range where measurements were to be taken.\n\nThe vertical dimension of both walls was 3 feet which was assumed sufficient to approximate an actual fuselage for use with a 4-foot propeller. The reinforced wooden (two thicknesses of $\\frac{3}{4}$-in. plywood) wall was 6 feet long and weighed approximately 145 pounds whereas the reinforced steel ($\\frac{3}{32}$-in. boiler plate) wall was 4 feet long and weighed approximately 100 pounds.\n\nEFFECTS OF VARIOUS PARAMETERS ON\n\nTOTAL OSCILLATING PRESSURES\n\nTip clearance.- Figure 6 illustrates the effect of tip clearance on the free-space oscillating pressure distribution. As clearance is reduced for a given tip Mach number, pressures all along a line parallel to the propeller axis tend to increase but the important change seems to occur in a region approximately one propeller radius wide in the vicinity of the plane of rotation. In this figure and in several succeeding ones the horizontal scale is $x/D$ and denotes distances from the plane of rotation; positive values denote positions ahead of the propeller plane and negative values denote positions behind it.\n\nBlade loading.- Figure 7 shows the extent to which the free-space pressure distribution may be changed, at a constant tip Mach number and clearance, by changing the blade loading. When the pressure ordinate is plotted as the ratio $C_p/C_p$ all data at a given tip Mach number can be compared on an equal power basis. Three different operating conditions are represented since at $\\beta_{0.75} = 8^\\circ$ the propeller is lightly loaded, at $\\beta_{0.75} = 15^\\circ$ it is heavily loaded but unstalled.", "timestamp": "2026-07-22T06:02:23.535286+00:00"} | |
| {"citation_id": "19930085972", "source_url": "https://ntrs.nasa.gov/api/citations/19930085972/downloads/19930085972.pdf", "page_number": 45, "total_pages": 46, "image_filename": "19930085972_p45.jpg", "text": "NACA RM L9B18\n43\n\nNeutral-point and tail-off aerodynamic-center location, $\\eta_p$ and $\\eta_0$, percent c' ($\\Delta=0$)\n\n| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |", "timestamp": "2026-07-22T06:02:23.963619+00:00"} | |
| {"citation_id": "19930093789", "source_url": "https://ntrs.nasa.gov/api/citations/19930093789/downloads/19930093789.pdf", "page_number": 27, "total_pages": 29, "image_filename": "19930093789_p27.jpg", "text": "```markdown\n26\n\nCONFIDENTIAL\n\nNACA RM NO. E8121\n\n(1/2) 13.25\nU = 645\n\nDesign point\n\nEquivalent mean blade speed $U(a_0/a_1)$, ft/sec\n\nBrake efficiency, $\\eta$\n\nTotal-pressure ratio, $p_1'/p_0'$\n\nEquivalent turbine shaft work, $E(a_0/a_1)^2$, Btu/lb\n\nEquivalent mean blade speed/equivalent weight flow, $U_0/\\sqrt{w_2g}$, ft/lb\n\nFigure 13. - Over-all performance chart with 0°-cone-angle stator and cylindrical shroud (configuration 3).\n\nNACA\n\n1021\n\n```", "timestamp": "2026-07-22T06:02:27.398962+00:00"} | |
| {"citation_id": "19930093769", "source_url": "https://ntrs.nasa.gov/api/citations/19930093769/downloads/19930093769.pdf", "page_number": 23, "total_pages": 39, "image_filename": "19930093769_p23.jpg", "text": "22\nCONFIDENTIAL\nNACA RM No. E8L10a\n\nCorrected net thrust, lb\nFuel\n$\\Delta$ AN-F-58\n$\\square$ Gasoline\n\n(c) Altitude, 20,000 feet; flight Mach number, 0.85.\n\nCorrected engine speed, rpm\nNACA\n\n(d) Altitude, 20,000 feet; flight Mach number, 1.00.\nFigure 4. - Continued. Comparison of corrected net thrust for AN-F-58\nfuel and gasoline at various altitudes and flight Mach numbers.\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:02:31.107648+00:00"} | |
| {"citation_id": "19930082613", "source_url": "https://ntrs.nasa.gov/api/citations/19930082613/downloads/19930082613.pdf", "page_number": 6, "total_pages": 46, "image_filename": "19930082613_p6.jpg", "text": "NACA TN 1938\n5\n\nChemical analysis. - An attempt was made to scrape corrosion products (scale) from the liner surfaces in order to determine the presence of sulfur. Samples large enough for chemical analysis could not be obtained, however, because the scale was both thin and tight. Analyses by X-ray and electron diffraction of the scale were attempted but no conclusions could be drawn from the data. The results seemed to indicate that oxides were present; however, positive identification of individual oxides was impossible with the techniques used. A large number of similar oxides and isomorphs, which may form from the alloying elements in Inconel, made the identification difficult. Carbon deposits, which were as thick as 1/16 inch and were present in all the liners, were scraped and sent to the National Bureau of Standards for quantitative chemical analyses for carbon and sulfur. In addition, a spectrographic analysis of the deposits was made.\n\nHeat treatments and mechanical finishing. - In order to determine if heat-treating would improve the resistance of Inconel liners to cracking and if engine runs involving heat-treated liners were warranted, preliminary investigations were made. Trial specimens were treated at 900°, 1600°, and 2200° F, air-cooled and water-quenched, examined metallographically, and hardness tested. The specimens were made of 1/32-inch dead soft Inconel and 5/8-inch holes were punched in them so that in addition to examining the general microstructure, the punched edges could be checked for distorted grains and the changes that the heat treatments produced. A specimen that was not heat-treated was used as a standard for comparison.\n\nThe 900° F heat treatment was recommended to give this alloy spring properties and also the best resistance to fatigue and high-temperature exposure (reference 1, p. 6). The 1600° F heat treatment was expected to soften the alloy by agglomerating precipitates and relieving stresses, whereas the 2200° F treatment was expected to be a solution treatment and to increase grain size.\n\nBecause the microstructural differences found in the trial specimens were significantly great, three type-B liners were selected from stock and were heat-treated in a neutral atmosphere at 900° F for 1 hour and air-cooled, at 1600° F for 2 hours and air-quenched, and at 2200° F for 2 hours and air-quenched.\n\nThe atmosphere was produced from propene, which had a sulfur content of 0.005 percent. After each sample, except the one treated at 900° F, had been held at temperature for the required time, it was quickly placed in a cylindrical furnace and air-quenched with a blast of air from all sides.", "timestamp": "2026-07-22T06:02:32.208136+00:00"} | |
| {"citation_id": "19930085880", "source_url": "https://ntrs.nasa.gov/api/citations/19930085880/downloads/19930085880.pdf", "page_number": 72, "total_pages": 96, "image_filename": "19930085880_p72.jpg", "text": "70\nNACA RM No. L9C03\n\nDraft, ft\n.64\n.56\n.48\n.40\n.32\n.24\n.16\n.08\n0\n0 .05 .10 .15 .20 .25 .30 .35\nWetted area, sq ft\n\nSpeed\n(fps)\n10 O\n15 □\n20 ◇\n25 △\n30 ▽\n35 △\n\n(a) $\\tau = 40$.\nNACA\nFigure 21.- Variation of draft with wetted area. Model 250B.", "timestamp": "2026-07-22T06:02:35.547360+00:00"} | |
| {"citation_id": "19930082566", "source_url": "https://ntrs.nasa.gov/api/citations/19930082566/downloads/19930082566.pdf", "page_number": 9, "total_pages": 44, "image_filename": "19930082566_p9.jpg", "text": "NACA TN No. 1889\n\nCalibration of Testing Machines\n\nThe lever K for applying the load was calibrated by noting simultaneous dial readings on a 10,000-pound dynamometer N and strain readings of a calibrated test bar inserted in place of the specimen S. The test bar was calibrated in a Baldwin-Southwark hydraulic testing machine. The strains of the steel test bar were measured by two SR-4 electric strain gages cemented to opposite sides of the bar.\n\nConcentricity of the axial tensile loading on the specimen was checked by measuring the elongation of the specimen at four locations equally spaced around the circumference. After adjustment of the holders, the strains were found to be in reasonable agreement for loads within the range of the tests. The maximum difference in the measured stress on opposite sides of the specimen was less than 1 percent.\n\nCalculations were also made to determine the error introduced in the axial-load values by neglecting the axial load produced by the inertia forces in the lever. These inertia forces were produced by the accelerations in the lever as the fluctuating axial load was applied. Calculation shows that the maximum error is less than 1 percent of the applied load.\n\nThe pressure gages were calibrated with a dead-weight gage tester. The maximum-pressure gage has a range of 0 to 5000 psi and the minimum-pressure gage a range of 0 to 2000 psi. Readings of the pressure were noted to the nearest 25 psi.\n\nMethod of Testing\n\nThe test procedure outlined in the following paragraphs applies to tests in which the specimen was subjected to both an axial load and internal pressure. For tests in which only axial load or internal pressure was used the procedure was simplified by the omission of some of the adjustments.\n\nAfter the dimensions of a specimen are measured, as explained in reference 2, the specimen is screwed into the specimen holders. The axial load is adjusted as follows: The axial load, corresponding to a given value, can be applied by adjusting the eccentric $E_1$ to a given position and fixing that position with self-locking set screws. With the eccentric $E_1$ (fig. 7) in its lowest position, a threaded turnbuckle above the dynamometer N is adjusted until the dynamometer registers the minimum load desired. The eccentric drive shaft is next rotated by hand to determine the maximum axial-load reading on the dynamometer. If this reading has changed, the above procedure is repeated until the correct minimum and maximum axial-load readings are registered on the dynamometer.", "timestamp": "2026-07-22T06:02:38.956608+00:00"} | |
| {"citation_id": "19930083192", "source_url": "https://ntrs.nasa.gov/api/citations/19930083192/downloads/19930083192.pdf", "page_number": 1, "total_pages": 149, "image_filename": "19930083192_p1.jpg", "text": "N 62 53976\n\nNACA TN 1976\n\nNATIONAL ADVISORY COMMITTEE\nFOR AERONAUTICS\n\nTECHNICAL NOTE 1976\n\nSUMMARY OF INFORMATION RELATING TO GUST\nLOADS ON AIRPLANES\n\nBy Philip Donely\n\nLangley Aeronautical Laboratory\nLangley Air Force Base, Va.\n\nCASE FILE\nCOPY\n\nNACA\n\nWashington\nNovember 1949", "timestamp": "2026-07-22T06:02:40.131019+00:00"} | |
| {"citation_id": "19930091993", "source_url": "https://ntrs.nasa.gov/api/citations/19930091993/downloads/19930091993.pdf", "page_number": 21, "total_pages": 21, "image_filename": "19930091993_p21.jpg", "text": "Positive directions of axes and angles (forces and moments) are shown by arrows\n\n| Axis | Force (parallel to axis) symbol | Moment about axis | | | Angle | | Velocities | |\n| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |\n| Designation | Symbol | Designation | Symbol | Positive direction | Designation | Symbol | Linear (component along axis) | Angular |\n| Longitudinal | $X$ | Rolling | $L$ | $Y \\longrightarrow Z$ | Roll | $\\phi$ | $u$ | $p$ |\n| Lateral | $Y$ | Pitching | $M$ | $Z \\longrightarrow X$ | Pitch | $\\theta$ | $v$ | $q$ |\n| Normal | $Z$ | Yawing | $N$ | $X \\longrightarrow Y$ | Yaw | $\\psi$ | $w$ | $r$ |\n\nAbsolute coefficients of moment\n$$C_l = \\frac{L}{qbS} \\quad (\\text{rolling})$$\n$$C_m = \\frac{M}{qcS} \\quad (\\text{pitching})$$\n$$C_n = \\frac{N}{qbS} \\quad (\\text{yawing})$$\n\nAngle of set of control surface (relative to neutral position), $\\delta$. (Indicate surface by proper subscript.)\n\n**4. PROPELLER SYMBOLS**\n\n$D$ Diameter\n$p$ Geometric pitch\n$p/D$ Pitch ratio\n$V'$ Inflow velocity\n$V_s$ Slipstream velocity\n$T$ Thrust, absolute coefficient $C_T = \\frac{T}{\\rho n^2 D^4}$\n$Q$ Torque, absolute coefficient $C_Q = \\frac{Q}{\\rho n^2 D^5}$\n\n$P$ Power, absolute coefficient $C_P = \\frac{P}{\\rho n^3 D^5}$\n$C_s$ Speed-power coefficient $= \\sqrt[5]{\\frac{\\rho V^5}{P n^2}}$\n$\\eta$ Efficiency\n$n$ Revolutions per second, rps\n$\\Phi$ Effective helix angle $= \\tan^{-1} \\left( \\frac{V}{2\\pi r n} \\right)$\n\n**5. NUMERICAL RELATIONS**\n\n1 hp = 76.04 kg-m/s = 550 ft-lb/sec\n1 metric horse-power = 0.9863 hp\n1 mph = 0.4470 mps\n1 mps = 2.2369 mph\n\n1 lb = 0.4536 kg\n1 kg = 2.2046 lb\n1 mi = 1,609.35 m = 5,280 ft\n1 m = 3.2808 ft", "timestamp": "2026-07-22T06:02:40.888307+00:00"} | |
| {"citation_id": "19930082918", "source_url": "https://ntrs.nasa.gov/api/citations/19930082918/downloads/19930082918.pdf", "page_number": 1, "total_pages": 62, "image_filename": "19930082918_p1.jpg", "text": "TN\n1940\nC-1\n\nNACA TN 1940\n\nNATIONAL ADVISORY COMMITTEE\nFOR AERONAUTICS\n\nTECHNICAL NOTE 1940\n\nFUNDAMENTAL EFFECTS OF AGING ON CREEP PROPERTIES OF\nSOLUTION-TREATED LOW-CARBON N-155 ALLOY\n\nBy D. N. Frey, J. W. Freeman, and A. E. White\n\nUniversity of Michigan\nENGINEERING DEPT. LIBRARY\nCHANCE-VOUGHT AIRCRAFT\nDALLAS, TEXAS\n\n[Figure: NACA logo]\n\nWashington\nAugust 1949", "timestamp": "2026-07-22T06:02:41.805267+00:00"} | |
| {"citation_id": "19930082703", "source_url": "https://ntrs.nasa.gov/api/citations/19930082703/downloads/19930082703.pdf", "page_number": 3, "total_pages": 28, "image_filename": "19930082703_p3.jpg", "text": "NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS\n\nTECHNICAL NOTE 1983\n\nLONGITUDINAL FLYING QUALITIES OF SEVERAL SINGLE-ROTOR\nHELICOPTERS IN FORWARD FLIGHT\n\nBy F. B. Gustafson, Kenneth B. Amer, C. R. Haig,\nand J. P. Reeder\n\nSUMMARY\n\nFlight-test measurements and corresponding pilot's opinions of the\nforward-flight longitudinal flying-qualities characteristics of several\nsingle-rotor helicopters are presented. A comparison which is signifi-\ncant in connection with the defining of satisfactory characteristics is\nthus provided. On the basis of the comparisons obtained, it is con-\ncluded that the most important consideration is the prevention of pro-\nlonged stick-fixed divergent tendencies. Additional improvement is\nconcluded to relate to the continuous development of normal acceleration\nin contrast to a pause in the development of acceleration during the\nfirst second following abrupt control deflection. These conclusions are\nalso expressed in the form of tentative flying-qualities requirements.\n\nA maneuver which brings out some of the principal characteristics\nis theoretically analyzed. It is concluded that the normal-acceleration\ncharacteristics appreciated by the pilot can be theoretically predicted.\n\nINTRODUCTION\n\nAs was indicated in reference 1, the National Advisory Committee\nfor Aeronautics is currently endeavoring to extend its work on require-\nments for satisfactory stability and control characteristics for air-\nplanes (references 2 and 3) in order to formulate similar requirements\nfor helicopters. In reference 1, one of the primary flying-qualities\nproblems of current helicopters is shown to be instability with angle of\nattack in forward flight; that is, the pilot must continually control\nagainst a divergent tendency following either longitudinal control\nmotion or a nose-up or nose-down disturbance. The longitudinal\nstability and control studies are at present far from being sufficient\nto determine the various combinations of parameters that will give sat-\nisfactory characteristics. Flight-test results which have been obtained\nfor three configurations do, however, provide a comparison in connection\nwith the defining of satisfactory longitudinal characteristics. These", "timestamp": "2026-07-22T06:02:44.294937+00:00"} | |
| {"citation_id": "19930082483", "source_url": "https://ntrs.nasa.gov/api/citations/19930082483/downloads/19930082483.pdf", "page_number": 22, "total_pages": 78, "image_filename": "19930082483_p22.jpg", "text": "20\nNACA TN No. 1807\n\nThe principal source of measured loss data was an 11-inch-diameter gas turbine. In order to obtain loss measurements, a dynamometer was used to motor this turbine rotor, with blading attached, in a stagnant medium.\n\nAfter machining off the blading to the root diameter, the rotor was motored again. Motoring was performed over a range of speeds for several values of gas density in the rotor housing. Bearing and gear losses were isolated by extrapolating the observed loss data to zero density.\n\nBearing loss. - A calibration of the mock-up of the lubricating system was made from which the flow rate to the journal-thrust and journal bearings could be determined over a wide range of operating oil temperatures and pressures. No turbine-shaft rotation was provided during this calibration.\n\nWeight-Flow Check\n\nWeight-flow measurements were made with the wheel removed at various degrees of admission. Partial admission was accomplished by blocking off fractions of the nozzle periphery. The inlet temperature was maintained at 800° R, the inlet pressures were varied over the same range as during the performance investigation with the back pressure reduced sufficiently to assure choking in the nozzles. This investigation confirmed that weight flow is directly proportional to the degree of admission.\n\nMETHODS\n\nCalculation Methods\n\nFull-admission performance. - Inlet total pressure was calculated on a continuity basis using the inlet static-pressure and total-temperature observations.\n\n$$p_1' = p_1 \\left[ \\frac{1}{2} + \\sqrt{\\frac{1}{4} + \\frac{1}{2g} \\left( \\frac{\\gamma-1}{\\gamma} \\right) \\left( \\frac{W}{p_1 A} \\right)^2 RT_1'} \\right]^{\\frac{\\gamma}{\\gamma-1}} \\quad (35)$$\n\nwhere A is the discharge-annulus area in square feet.\n\nThe discharge total pressure was obtained by computing the axial component of the velocity of the discharge gases using", "timestamp": "2026-07-22T06:02:46.588503+00:00"} | |
| {"citation_id": "19930085972", "source_url": "https://ntrs.nasa.gov/api/citations/19930085972/downloads/19930085972.pdf", "page_number": 46, "total_pages": 46, "image_filename": "19930085972_p46.jpg", "text": "[No readable text detected]", "timestamp": "2026-07-22T06:02:50.166134+00:00"} | |
| {"citation_id": "19930082472", "source_url": "https://ntrs.nasa.gov/api/citations/19930082472/downloads/19930082472.pdf", "page_number": 31, "total_pages": 34, "image_filename": "19930082472_p31.jpg", "text": "NACA TN No. 1797\n29\n\nUnflagged symbols indicate\nupper surface.\nFlagged symbols indicate\nlower surface.\n\nSpanwise\nstation, 2y/b\n20.9%\n28.1%\n41.7%\n57.4%\n71.4%\n85.0%\n92.5%\n96.2%\n\nPressure coefficient, P\n-20\n-16\n-12\n-8\n-4\n0\n4\n8\n\nChordwise station, x/c\n.2\n.6\n.8\n1.0\n\n(h) $\\alpha=248^\\circ$\n\nFigure 5—Continued.\n\n[Figure: NACA logo]", "timestamp": "2026-07-22T06:02:50.189913+00:00"} | |
| {"citation_id": "19930082592", "source_url": "https://ntrs.nasa.gov/api/citations/19930082592/downloads/19930082592.pdf", "page_number": 8, "total_pages": 50, "image_filename": "19930082592_p8.jpg", "text": "NACA TN 1914\n\nThe oxide coating formed on the cobalt ceramals was found to be very hard and tightly adherent. The coating forms along an interface parallel to the surface and some tendency exists for the coating to chip along a plane within the oxide layer. The coating on the cobalt ceramals is more complex than that found on the molybdenum or tungsten ceramals. This coating consists of several phases, which vary in concentration with distance from the oxidation interface.\n\nAll the coatings contained titanium dioxide $\\mathrm{TiO}_{2}$. The presence of tungsten trioxide $\\mathrm{WO}_{3}$ was detected in the tungsten ceramals, and some molybdenum trioxide $\\mathrm{MoO}_{3}$ was present in the molybdenum ceramals. In the cobalt ceramals, cobaltous cobaltic oxide $\\mathrm{CoO} \\cdot \\mathrm{Co}_{2} \\mathrm{O}_{3}$ was detected at the oxidation interface and cobalt titanate $\\mathrm{CoTiO}_{3}$ was detected in the inner oxide layer.\n\nMolybdenum trioxide $\\mathrm{MoO}_{3}$ sublimes as a volatile oxide between $480^{\\circ}$ and $840^{\\circ} \\mathrm{F}$ (reference 4). This temperature is well below the experimental temperatures and from this consideration alone no protective value would be expected from $\\mathrm{MoO}_{3}$. Another factor indicating that $\\mathrm{MoO}_{3}$ would have little protective value is its specific-molecular-volume ratio of 3.4. The specific-molecular-volume ratio is the ratio of the specific molecular volume of the oxide to that of the metal. The specific-molecular-volume ratio of $\\mathrm{WO}_{3}$ is also 3.4 and it is well established that the oxide formed on metallic tungsten does not protect the metal from further oxidation (references 5 and 6). The melting point of $\\mathrm{WO}_{3}$ is $2650^{\\circ} \\mathrm{F}$ and some evaporation of a $\\mathrm{WO}_{3}$ coating will take place at $1470^{\\circ} \\mathrm{F}$ (reference 7). It has been reported that $\\mathrm{WO}_{3}$ sinters at $1650^{\\circ} \\mathrm{F}$ (reference 7). The commonly formed oxide of cobalt, cobaltous oxide $\\mathrm{CoO}$ melts at $3515^{\\circ} \\mathrm{F}$ and melting this oxide in air at atmospheric pressure is not accompanied by great amounts of volatilization.\n\nThe two factors, low volatilization temperature of the oxide and high specific volume of the oxide, would both indicate that the oxide coating formed on molybdenum ceramals would have little protective value. As the $\\mathrm{MoO}_{3}$ forms it expands and breaks away from the body at the oxidation interface also fracturing the titanium carbide $\\mathrm{TiC}$ as well as any $\\mathrm{TiO}_{2}$ formed upon oxidation of the $\\mathrm{TiC}$. The $\\mathrm{MoO}_{3}$ then volatilizes and diffuses to the surface leaving a loosely packed porous coating that has practically no resistance to the diffusion of oxygen. This view of the mechanism of oxidation of the molybdenum ceramals is substantiated by the curves plotted in figure 1, which indicate that the oxidation increase with time occurs as a straight line on rectangular coordinates.", "timestamp": "2026-07-22T06:02:50.430534+00:00"} | |
| {"citation_id": "19930082511", "source_url": "https://ntrs.nasa.gov/api/citations/19930082511/downloads/19930082511.pdf", "page_number": 96, "total_pages": 99, "image_filename": "19930082511_p96.jpg", "text": "```markdown\n94\n\n[Figure: Diagram showing a lifting element with dimensions labeled $3R$, $R$, $\\xi R$, and $aR$, with a velocity vector $V$]\n\n$\\delta$\n.25\n.20\n.15\n.10\n.05\n0\n-.05\n-.10\n-.15\n-.20\n-.25\n\n-2 -1.6 -1.2 -.8 -.4 0 .4 .8 1.2 1.6 2.0 2.4 2.8 3.2 3.6\n\nDistance from lifting element, $\\xi$, units of tunnel radius\n\nOpen tunnel\n\nNACA\n\n$a = -0.1$\n$a = -0.4$\n$a = -0.7$\n$a = -1.0$\n\nClosed tunnel\n\nFigure 24.- Tunnel-induced velocity parameter along tunnel axis for several positions of the lifting element in a closed-open-closed circular tunnel.\n\nNACA TN NO. 1826\n```", "timestamp": "2026-07-22T06:02:52.408610+00:00"} | |
| {"citation_id": "19930086076", "source_url": "https://ntrs.nasa.gov/api/citations/19930086076/downloads/19930086076.pdf", "page_number": 41, "total_pages": 50, "image_filename": "19930086076_p41.jpg", "text": "NACA RM E9F09\n39\n\n[Figure: Cutaway view of a damaged metal flame holder assembly. A scale bar labeled \"INCHES\" is visible at the bottom right of the image, along with a NACA identification stamp.]\n\nFigure 15. - Cutaway view of flame holder 11 showing condition after 5 minutes of operation. Note molybdenum prism.", "timestamp": "2026-07-22T06:02:53.054212+00:00"} | |
| {"citation_id": "19930082546", "source_url": "https://ntrs.nasa.gov/api/citations/19930082546/downloads/19930082546.pdf", "page_number": 13, "total_pages": 65, "image_filename": "19930082546_p13.jpg", "text": "12\nNACA TN No. 1870\n\nat the tips, whereas at $\\beta_{0.75} = 20^\\circ$ it is stalled. For the condition $\\beta_{0.75} = 20^\\circ$, the thrust component of pressure becomes of small importance relative to the torque component, and the pressure distribution tends to peak in the plane of rotation. For the unstalled condition where $C_T$ is relatively large, the free-space pressures are a maximum at approximately 1/8 of a diameter ahead of and behind the plane of rotation.\n\n**Power coefficient.**- In figure 8 some experimental free-space pressure coefficients $C_p$ are plotted against power coefficient $C_P$ for four different propellers and at two different tip Mach numbers. At a given tip Mach number the relation between $C_p$ and $C_P$ is seen to be approximately linear. A comparison between the total pressures produced by a two-blade and a four-blade propeller at equal power coefficients is given. As is indicated in figure 8, less pressure is produced by the four-blade propeller than for the two-blade propeller at the same power coefficient, although at tip Mach number 1.00 the differences are relatively small. Figure 8 shows that comparable data for the NACA 4-(5)(08)-03, the NACA 4-(3)(06.3)-06, and the Clark Y propeller are in good agreement. Blade plan form and solidity are thus not considered to be significant parameters. In addition for a given $M_t$, $C_P$, and $d/D$, pressure coefficients for propellers of different diameter are shown to be approximately equal.\n\n**Tip shape.**- The three two-blade propellers for which data are given in figure 8 differ in plan-form shape and in the shank sections but all have rounded tips. Thus it is seen that the pressures produced are not affected very much by small differences at the inboard stations. Two-blade configurations of the NACA 4-(5)(08)-03 propeller and the square-tip propeller were tested to determine the effect of tip shape. These propellers have identical airfoil section, and the only essential difference in plan form is at the tips. Both propellers were tested at the same blade angle and tip speed and at approximately the same power to get comparable data. Results shown in figure 9 indicate that blade tip shape is not a significant parameter.\n\n**Effect of reflecting surfaces.**- In order to determine the effect that a reflecting surface has on the impinging pressures, tests were made with a flat vertical wall and a circular-shaped wall. These results are compared to corresponding free-space data in figure 10. Pressures measured in the plane of a flat vertical wall are seen to be approximately double the free-space values. Corresponding data for a circular wall indicate an increase over the free-space values, but this increase is somewhat less than that for the flat wall.\n\n**Comparison with full-scale data.**- In order to compare these measurements with full-scale data some check points for the static", "timestamp": "2026-07-22T06:03:08.344119+00:00"} | |
| {"citation_id": "19930093789", "source_url": "https://ntrs.nasa.gov/api/citations/19930093789/downloads/19930093789.pdf", "page_number": 28, "total_pages": 29, "image_filename": "19930093789_p28.jpg", "text": "NACA RM No. E8121 CONFIDENTIAL 27\n\n[Handwritten annotation in red ink: (leaving losses not included)]\n\nBrake efficiency, $\\eta$\n\nTotal-pressure ratio, $p_1'/p_3'$\n3.50\n2.00\n1.25\n\nBlade-to-jet speed ratio, $U/V_j$\n\n[NACA logo]\n\nFigure 14. - Efficiency of configuration 2 at various pressure ratios.\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:03:12.774214+00:00"} | |
| {"citation_id": "19930093769", "source_url": "https://ntrs.nasa.gov/api/citations/19930093769/downloads/19930093769.pdf", "page_number": 24, "total_pages": 39, "image_filename": "19930093769_p24.jpg", "text": "NACA RM No. E8L10a CONFIDENTIAL 23\n\n1070\n\nCorrected net thrust, lb\n\nFuel\n$\\Delta$ AN-F-58\n$\\square$ Gasoline\n\n(e) Altitude, 35,000 feet; flight Mach number 1.0.\n\nCorrected engine speed, rpm\n\n(f) Altitude, 50,000 feet; flight Mach number, 0.85.\n\nFigure 4. - Concluded. Comparison of corrected net thrust for AN-F-58 fuel and gasoline at various altitudes and flight Mach numbers.\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:03:14.233504+00:00"} | |
| {"citation_id": "19930082646", "source_url": "https://ntrs.nasa.gov/api/citations/19930082646/downloads/19930082646.pdf", "page_number": 5, "total_pages": 37, "image_filename": "19930082646_p5.jpg", "text": "```markdown\n4\nNACA TN 1980\n\n## RESULTS AND DISCUSSION\n\n### Longitudinal Stability\n\n**Trim limits of stability.**-- The trim limits of stability for the configuration with the warped forebody and extended afterbody are presented in figure 4, together with those for the basic hull. The differences in the trim limits for the modified and basic hulls are consistent with those expected on the basis of previous investigations of forebody and afterbody modifications as described in references 1 and 2, respectively. The peak of the lower limit for the modified hull was lower than that of the basic hull. This change is similar to that obtained for the model with an extended afterbody and is in agreement with trends noted in investigations of other models (reference 7). Warping the forebody resulted in a shift of the entire lower trim limit to lower speeds so that, for most speeds beyond the hump, the lower limit was about $2^\\circ$ below that of the basic hull. Since lower-limit porpoising is principally a forebody phenomenon, extending the afterbody would not be expected to affect this limit except near hump speeds. Both branches of the upper trim limit were lowered approximately $1^\\circ$ at high speeds. The upper-limit porpoising, being affected principally by the afterbody, is not greatly influenced by the presence of the warped forebody and, consequently, the behavior of the model with the warped forebody and the extended afterbody was similar to that of the model with the extended afterbody alone. The available aerodynamic trimming moment was not great enough to trim the model to the upper limit at speeds below 64 miles per hour, principally because of the presence of the long afterbody. The stable range of trims was therefore substantially increased throughout the entire speed range up to take-off by combining the warped forebody with the extended afterbody.\n\n**Center-of-gravity limits of stability.**-- Representative trim tracks for take-off at several positions of the center of gravity and elevator deflections are presented in figure 5 for the modified and basic hulls. From such trim tracks, a plot of maximum amplitude of porpoising against center-of-gravity position was obtained. The maximum amplitude of porpoising is defined as the difference between the maximum and minimum trims that occurred during the greatest trim cycle. The maximum amplitudes of porpoising for the modified hull are plotted in figure 6 and compared in figure 7 with those for the basic hull. The position of the center of gravity at which lower-limit porpoising first appeared was shifted slightly aft for the modified hull. (See fig. 7(a).) Once lower-limit porpoising was encountered, the increase in amplitude with forward movement of the center of gravity was less for the modified hull than for the basic hull. This behavior is similar to that noted for the model with the extended afterbody, reference 2, and is\n```", "timestamp": "2026-07-22T06:03:14.424424+00:00"} | |
| {"citation_id": "19930085880", "source_url": "https://ntrs.nasa.gov/api/citations/19930085880/downloads/19930085880.pdf", "page_number": 73, "total_pages": 96, "image_filename": "19930085880_p73.jpg", "text": "NACA RM No. L9C03\n71\n\nDraft, ft\n.64\n.56\n.48\n.40\n.32\n.24\n.16\n.08\n0\n\nSpeed\n(fps)\n10 O\n15 □\n20 ◇\n25 △\n30 ▽\n\n0 .05 .10 .15 .20 .25 .30 .35\nWetted area, sq ft\n(b) $\\tau = 80$.\nFigure 21.- Continued.\n\n[Figure: A scatter plot showing Draft, ft on the y-axis and Wetted area, sq ft on the x-axis. Data points for different speeds (10, 15, 20, 25, 30 fps) are plotted with different symbols (O, □, ◇, △, ▽) and show a generally increasing trend. A legend is present in the upper left of the plot area. A NACA logo is in the bottom right corner.]", "timestamp": "2026-07-22T06:03:19.025641+00:00"} | |
| {"citation_id": "19930082613", "source_url": "https://ntrs.nasa.gov/api/citations/19930082613/downloads/19930082613.pdf", "page_number": 7, "total_pages": 46, "image_filename": "19930082613_p7.jpg", "text": "6\nNACA TN 1938\n\nThree additional type-B liners were heat-treated at these same temperatures. Before being heat-treated, however, the punched holes were reamed, sanded, and vapor blasted. An additional liner was also mechanically finished but not heat-treated.\n\nReaming, sanding, and vapor blasting was employed because information from the metallographic examinations indicated that service life might be improved by removing the roughness of the edges produced by punching. The procedure was as follows: All air-intake holes and all louver holes were reamed by hand. The air-intake holes were large enough to sand by hand but the louver holes had to be vapor blasted. Vapor blasting is very similar to sandblasting, the chief difference being that the abrasive particles are suspended in a liquid rather than in air. The reaming and the sanding removed a few thousandths of an inch of metal from the holes. Vapor blasting was intended to smooth the edges by a cutting action or by hammering shut the microscopic fissures.\n\nThese seven liners were then installed in an engine with ordinary liners spaced between them. The engine was run for 25 cycles of the accelerated-life run (a total of 8 hr and 20 min), after which all the liners were removed and inspected for cracks. The position and the length of each crack and notations about buckling were recorded. The engine was reassembled and run for 25 more cycles and the inspection procedure was repeated.\n\nThe reaming, sanding, and vapor-blasting treatment seemed to improve the resistance of the liners to cracking and therefore a new set of 14 as-fabricated liners was selected to verify the results. Seven of these liners were reamed, sanded, vapor blasted, and installed with ordinary liners in alternate positions. The engine was run for 25 cycles and the liners inspected for cracks. The data previously described for the first trials of this type were again recorded. The engine was then run again for 25 cycles and the liners were reinspected.\n\nRESULTS\n\nGeneral description of macrocracks. - Almost all cracks started from the stress-relieving holes of the louvers. The two most common types of crack are shown in figure 3. (See also fig. 4.)\n\nThese cracks originated in the upper bend of the louver flap at the inner edges of the stress-relieving holes (fig. 3(a), point 1). They proceed in a direction approximately perpendicular to the holes for a distance of 1/32 to 1/16 inch. The cracks deviate from their", "timestamp": "2026-07-22T06:03:24.845096+00:00"} | |
| {"citation_id": "19930082472", "source_url": "https://ntrs.nasa.gov/api/citations/19930082472/downloads/19930082472.pdf", "page_number": 32, "total_pages": 34, "image_filename": "19930082472_p32.jpg", "text": "30\nNACA TN No. 1797\n\nUnflagged symbols indicate\nupper surface.\nFlagged symbols indicate\nlower surface.\n\nSpanwise\nstation, 2y/b\n20.9%\n28.1%\n41.7%\n57.4%\n71.4%\n85.0%\n92.5%\n96.2%\n\nPressure coefficient, P\n-24\n-20\n-16\n-12\n-.8\n-.4\n0\n.4\n.8\n\nChordwise station, x/c\n.2\n.6\n.8\n1.0\n\nNACA\n\n(i) $\\alpha=3.08^\\circ$\n\nFigure 5.—Concluded.", "timestamp": "2026-07-22T06:03:26.010007+00:00"} | |
| {"citation_id": "19930086076", "source_url": "https://ntrs.nasa.gov/api/citations/19930086076/downloads/19930086076.pdf", "page_number": 42, "total_pages": 50, "image_filename": "19930086076_p42.jpg", "text": "[No readable text detected]", "timestamp": "2026-07-22T06:03:30.231974+00:00"} | |
| {"citation_id": "19930082511", "source_url": "https://ntrs.nasa.gov/api/citations/19930082511/downloads/19930082511.pdf", "page_number": 97, "total_pages": 99, "image_filename": "19930082511_p97.jpg", "text": "NACA TN No. 1826\n\n.25\n.20\n.15\n.10\n.05\n0\n-.05\n-.10\n-.15\n-.20\n-.25\n\na = -1.0\na = -0.7\na = -0.4\na = -0.1\n\n-8 -4 0 .4 .8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0\nDistance from entrance, ξ-a, units of tunnel radius\n\nFigure 25.- Tunnel-induced velocity parameter along tunnel axis for several positions of the lifting element in a closed-open-closed circular tunnel. (Same curves as on fig. 24, but plotted against distance from entrance.)\n\n[Figure: Graph showing δ vs. distance from entrance for different values of a]\n\nNACA\n\n95", "timestamp": "2026-07-22T06:03:31.598256+00:00"} | |
| {"citation_id": "19930082918", "source_url": "https://ntrs.nasa.gov/api/citations/19930082918/downloads/19930082918.pdf", "page_number": 2, "total_pages": 62, "image_filename": "19930082918_p2.jpg", "text": "```markdown\nNATIONAL ADVISORY COMMITTEE FOR AERONAUTICS\n\nTECHNICAL NOTE 1940\n\nFUNDAMENTAL EFFECTS OF AGING ON CREEP PROPERTIES OF\nSOLUTION-TREATED LOW-CARBON N-155 ALLOY\n\nBy D. N. Frey, J. W. Freeman, and A. E. [illegible]\n\nSUMMARY\n\nA method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. This method uses metallographic examination - both optical and electronic - studies of X-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions.\n\nIn accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon N-155 alloy at $1200^\\circ$ F. The test stock was solution-treated at $2200^\\circ$ F for 10 hours, water-quenched, and aged for time periods up to 1000 hours at $1200^\\circ$, $1400^\\circ$, and $1600^\\circ$ F.\n\nCorrelation of the structural effects of aging with the mechanical properties indicated that aging had the following effects on solution-treated low-carbon N-155 alloy:\n\n(1) Aging resulted in progressive lowering of short-time creep resistance through removal from solid solution of large-radius or substitutional atoms by precipitation.\n\n(2) Short-time aging resulted in marked increase in short-time rupture strengths through the growth of a grain boundary phase which eliminated intergranular cracking. Long-time aging resulted in little further change in short-time rupture strength.\n\n(3) Because aging lowered the creep resistance while raising the rupture strength, aged material exhibited greater ductility before fracture than unaged material.\n\nCalculations are carried out to show the probable character of the strain field induced in the solution-treated state by the presence of the large-radius atoms - molybdenum, tungsten, and columbium - and the substitutional atoms - hydrogen and carbon. The effect of this strain field on the creep resistance is also considered quantitatively.\n\n[annotation: ENGINEERING DEPT. LIBRARY CHANCE-VOUGHT AIRCRAFT DALLAS, TEXAS]\n```", "timestamp": "2026-07-22T06:03:33.235403+00:00"} | |
| {"citation_id": "19930083221", "source_url": "https://ntrs.nasa.gov/api/citations/19930083221/downloads/19930083221.pdf", "page_number": 1, "total_pages": 47, "image_filename": "19930083221_p1.jpg", "text": "Y 3.N21/5:6/1824\nGOVT. DOC.\n\nNACA TN No. 1824\n\nNATIONAL ADVISORY COMMITTEE\nFOR AERONAUTICS\n\nTECHNICAL NOTE\nNo. 1824\n\nLINEARIZED COMPRESSIBLE-FLOW THEORY\nFOR SONIC FLIGHT SPEEDS\n\nBy Max. A. Heaslet, Harvard Lomax, and\nJohn R. Spreiter\n\nAmes Aeronautical Laboratory,\nMoffett Field, Calif.\n\n[Figure: NACA logo]\n\nWashington\nMarch 1949\n\n[Stamp: MAR 16 1949]\nBUSINESS, SCIENCE\n& TECHNOLOGY DEP'T.", "timestamp": "2026-07-22T06:03:33.866080+00:00"} | |
| {"citation_id": "19930082483", "source_url": "https://ntrs.nasa.gov/api/citations/19930082483/downloads/19930082483.pdf", "page_number": 23, "total_pages": 78, "image_filename": "19930082483_p23.jpg", "text": "NACA TN No. 1807\n\nequation (9) of reference 6 and adding the corresponding velocity pressure to the measured discharge static pressure. The equation so obtained for calculating discharge total pressure is\n\n$$\np_{e}^{\\prime}=p_{e}\\left[\\frac{1}{2}+\\sqrt{\\frac{1}{4}+\\frac{1}{2 g}\\left(\\frac{\\gamma-1}{\\gamma}\\right)\\left(R T_{1}^{\\prime}-\\frac{\\gamma-1}{\\gamma} \\frac{p}{W}\\right)\\left(\\frac{W}{p_{e} A_{e}}\\right)^{2}}\\right]^{\\frac{\\gamma}{\\gamma-1}}\n$$\n\nThe ideal power input can then be calculated from equation (1), which becomes\n\n$$\n\\text { ideal power }=W c_{p} T_{1}^{\\prime}\\left[1-\\left(\\frac{p_{e}^{\\prime}}{p_{1}^{\\prime}}\\right)^{\\frac{\\gamma-1}{\\gamma}}\\right]\n$$\n\nThe turbine efficiency for the full-peripheral admission runs was taken as the ratio of the measured turbine power output to the calculated ideal power.\n\nBecause the pressure ratio across the turbine was regulated by setting the inlet total pressure and the discharge static pressure, there was some deviation in total-pressure ratio due to the variation of discharge total pressure with turbine power extraction. For comparison, it is therefore necessary to correct the turbine power output for this deviation from the nominal total-pressure ratio. The correction factor employed is the ratio of the isentropic enthalpy drop based on the nominal total-pressure ratio to the corresponding drop based on the actual total-pressure ratio.\n\nPartial-admission performance. - Performance calculations for the runs with partial admission were similar to those for full admission. However, in computing the axial component of the discharge velocity, it was assumed that the active flow area at the discharge measuring station immediately downstream of the rotor was proportional to the amount of active nozzle arc. The observations previously mentioned, which were made at the measuring station in the plane at the tip of the tail cone, indicate that the rate of gas diffusion in the discharge section is not rapid and would serve to validate the assumption.\n\nRotor-tip leakage loss. - Leakage loss was taken as the energy contained in the active gas that passes through the clearance space between the rotor-blade tips and the stationary turbine outer casing. The percentage of leakage weight flow was calculated using equation (12).", "timestamp": "2026-07-22T06:03:36.728774+00:00"} | |
| {"citation_id": "19930085485", "source_url": "https://ntrs.nasa.gov/api/citations/19930085485/downloads/19930085485.pdf", "page_number": 1, "total_pages": 26, "image_filename": "19930085485_p1.jpg", "text": "NACA RM No. L8K02\n\nFILE COPY\nNO 6\n\nCONFIDENTIAL\n\nCopy No. 211\nRM No. L8K02\n\n[Figure: NACA wing logo]\n\nNACA\n\nRESEARCH MEMORANDUM\n\nAERODYNAMIC CHARACTERISTICS AT SUBSONIC AND TRANSONIC\nSPEEDS OF A 42.7° SWEPTBACK WING MODEL HAVING AN\nAILERON WITH FINITE TRAILING-EDGE THICKNESS\n\nBy\nThomas R. Turner, Vernard E. Lockwood,\nand Raymond D. Vogler\n\nTHIS DOCUMENT ON LOAN FROM THE FILES OF\nLangley Aeronautical Laboratory\nLangley Field, Va.\n\nNATIONAL ADVISORY COMMITTEE FOR AERONAUTICS\nLANGLEY AERONAUTICAL LABORATORY\nLANGLEY FIELD, HAMPTON, VIRGINIA\n\nCLASSIFIED DOCUMENT\n\nThis document contains classified information affecting the National Defense of the United States within the meaning of the Espionage Act, USC 50:31 and 32. Its transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law. Information so classified may be imparted only to persons in the military and naval services of the United States, appropriate civilian officials and employees of the Federal Government who have a legitimate interest therein, and to United States citizens of known loyalty who are necessarily must be informed thereof.\n\nCLASSIFICATION CHANGED TO\nUNCLASSIFIED\nDATE 8-18-54\nAUTHORITY MR. J. W. CROWLEY\nCHANGE NO 2404\nE.L.B.\n\nRETURN TO THE ABOVE\nREPRINTS FOR PUBLICATIONS SHOULD BE ADDRESSED AS FOLLOWS:\nNATIONAL ADVISORY COMMITTEE FOR AERONAUTICS\n1512 H STREET, N. W.\nWASHINGTON 25, D. C.\n\nNATIONAL ADVISORY COMMITTEE\nFOR AERONAUTICS\nWASHINGTON\nJanuary 12, 1949\n\nCONFIDENTIAL", "timestamp": "2026-07-22T06:03:36.903366+00:00"} | |
| {"citation_id": "19930082592", "source_url": "https://ntrs.nasa.gov/api/citations/19930082592/downloads/19930082592.pdf", "page_number": 9, "total_pages": 50, "image_filename": "19930082592_p9.jpg", "text": "8\nNACA TN 1914\n\nA plot of the depth of oxide formed on the tungsten cermals against time on semilogarithmic coordinate paper is presented in figure 4(d). The oxide layer formed has some protective action but not as much as would be expected if a dense, homogeneous oxide were formed. This result may be expected, considering that the $WO_3$ formed will break away from the oxidation interface, carrying the $TiO_2$ formed and any $TiC$ remaining; but because the $WO_3$ has a low vapor pressure, the coating will not volatilize and at the two higher test temperatures some sintering of the oxide may have occurred. The building up of the oxide layer, even a rather broken layer, will afford some resistance to oxidation diffusion especially if the oxide coating is partly sintered.\n\nComparison of figures 6(d) and 4(d) indicates that the oxide penetration of the cobalt cermals proceeds at approximately the same rate as for the tungsten cermals at $1785^\\circ$ and $2000^\\circ$ F. At $1625^\\circ$ F, the 5- and 10-percent-tungsten cermals have better oxidation resistance than the 5- and 10-percent-cobalt cermals. The molybdenum cermals are in all cases inferior to the cobalt and tungsten cermals.\n\nThe type of oxide formed on a 30-percent-molybdenum specimen oxidized at $1785^\\circ$ F for 7 hours is shown in figure 8. The line of demarcation between the oxide and the ceramal is even and easily distinguished. If molybdenum is added to the ceramal in amounts that exceed the solubility of molybdenum in titanium carbide, the excess molybdenum will form a grain-boundary layer surrounding the titanium-carbide grains. The formation of such a grain-boundary area could produce a more rapid penetration of the oxidation reaction along the grain boundaries. In the 30-percent-molybdenum ceramal (fig. 9), the grain boundary does not appear to contain an appreciable quantity of a grain-boundary phase and the photomicrograph of the unetched oxidation interface of the same material (fig. 10) shows that the oxidation proceeds as a linear front without marked grain-boundary penetration.\n\nIn examining the temperature dependence of the oxidation-rate constant of the molybdenum cermals (fig. 2), it is evident that the oxidation rate of the 20- and 30-percent-molybdenum cermals at $1625^\\circ$ F is lower than would be expected if the oxidation mechanism remained unchanged. A possible explanation of the low oxidation rates may be brought out by examination of the photomicrograph of figure 11. The line following the contour of the oxidation interface may mark the vaporization interface of the $MoO_3$. This line was also found within the oxide layer of the 10-percent molybdenum ceramal oxidized at $1625^\\circ$ F but was not visible on the 20- and 30-percent-molybdenum cermals oxidized at $1625^\\circ$ F. If the assumption is made", "timestamp": "2026-07-22T06:03:42.841240+00:00"} | |
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