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Accurate calculation of multispar cantilever and semicantilever wings with parallel webs under direct and indirect loading

Description: In the present report the computation is actually carried through for the case of parallel spars of equal resistance in bending without direct loading, including plotting of the influence lines; for other cases the method of calculation is explained. The development of large size airplanes can be speeded up by accurate methods of calculation such as this.
Date: March 1932
Creator: Sanger, Eugen

An accurate method of measuring the moments of inertia of airplanes

Description: From Summary: "This note contains a description of an improved apparatus and procedure used by the NACA for determining the moments of inertia of airplanes. The method used, based on the pendulum theory, is similar to that previously used, but a recent investigation of its accuracy has resulted in the improvements described herein. The error, when using the new apparatus and procedure, has been found to be of the order of 1 per cent."
Date: October 1930
Creator: Miller, M P

Acoustic analysis of ram-jet buzz

Description: From Introduction: "The surging of a system containing a centrifugal- or axial-flow compressor (e.g., refs. 1 to 4) is an example of self-sustained oscillation. Inlets designed for supersonic jet engines also have been observed to induce oscillations (e.g., refs. 5 to 11) which are usually referred to as "buzz." The origin of buzz in ram-jet engines is the subject of the present report."
Date: November 1955
Creator: Mirels, Harold

Acoustic radiation from two-dimensional rectangular cutouts in aerodynamic surfaces

Description: From Introduction: "The experiments in high-speed flow showed that an intense, high-frequency acoustic radiation is an essential feature of the problem. Consequently, a study of the acoustic field (involving schlieren observations and frequency and intensity measurements) was undertaken. This report presents the salient features of the study, which was mainly exploratory."
Date: August 1955
Creator: Krishnamurty, K

Acoustic, thrust, and drag characteristics of several full-scale noise suppressors for turbojet engines

Description: From Introduction: " Considerable analytical and experimental research has been done to find means of reducing the noise levels of the turbojet transports. Noise levels can be decreased by engine redesign to reduce the jet-exit velocity (ref. 1), proper flight-climb techniques (ref. 2), and the use of noise-suppression exhaust nozzles (refs. 3 to 5). The present report is concerned with the last method."
Date: April 1958
Creator: Ciepluch, Carl C; North, Warren J; Coles, Willard D & Antl, Robert J

Activation of hydrocarbons and the octane number

Description: This report presents an examination of the history of research on engine knocking and the various types of fuels used in the investigations of this phenomenon. According to this report, the spontaneous ignition of hydrocarbons doped with oxygen follows the logarithmic law within a certain temperature range, but not above 920 degrees K. Having extended the scope of investigations to prove hydrocarbons, the curves of the mixtures burned by air should then be established by progressive replacement of pure iso-octane with heptane. Pentane was also examined in this report.
Date: October 1939
Creator: Peschard, Marcel

An active particle diffusion theory of flame quenching for laminar flames / Dorothy M. Simon and Frank E. Belles

Description: An equation for quenching distance based on the destruction of chain carriers by the surface is derived. The equation expresses the quenching distance in terms of the diffusion coefficients and partial pressures of the chain carriers and gas phase molecules, the efficiency of the surface as a chain breaker, the total pressure of the mixture, and a constant which depends on the geometry of the quenching surface. Quenching distances measured by flashback for propane-air flames are shown to be consistent with the mechanism. The derived equation is used with the lean inflammability limit and a rate constant calculated from burning velocity data to estimate quenching distances for propane-air (hydrocarbon lean) flames satisfactorily.
Date: March 4, 1952
Creator: Simon, Dorothy M & Belles, Frank E

Adaptation of a Cascade Impactor to Flight Measurement of Droplet Size in Clouds

Description: A cascade impactor, an instrument for obtaining: the size distribution of droplets borne in a low-velocity air stream, was adapted for flight cloud droplet-size studies. The air containing the droplets was slowed down from flight speed by a diffuser to the inlet-air velocity of the impactor. The droplets that enter the impactor impinge on four slides coated with magnesium oxide. Each slide catches a different size range. The relation between the size of droplet impressions and the droplet size was evaluated so that the droplet-size distributions may be found from these slides. The magnesium oxide coating provides a permanent record. of the droplet impression that is not affected by droplet evaporation after the. droplets have impinged.
Date: September 18, 1951
Creator: Levine, Joseph & Kleinknecht, Kenneth S.

Adaptation of aeronautical engines to high altitude flying

Description: Report discussing Issues and techniques relative to the adaptation of aircraft engines to high altitude flight. Covered here are the limits of engine output, modifications and characteristics of high altitude engines, the influence of air density on the proportions of fuel mixtures, methods of varying the proportions of fuel mixtures, the automatic prevention of fuel waste, and the design and application of air pressure regulators to high altitude flying. Summary: 1. Limits of engine output. 2. High altitude engines. 3. Influence of air density on proportions of mixture. 4. Methods of varying proportions of mixture. 5. Automatic prevention of fuel waste. 6. Design and application of air pressure regulators to high altitude flying.
Date: May 1923
Creator: Kutzbach, K

Adaptation of Combustion Principles to Aircraft Propulsion, Volume 2, Combustion in Air-Breathing Jet Engines

Description: This volume continues the NACA study of combustion principles for aircraft propulsion. The various aspects of combustion pertinent to jet engines are organized and interpreted with quite extensive information, particularly for basic or fundamental. subject matter. The report concerns only air-breathing engines and hydrocarbon fuels, and not rocket engines and high-energy fuels. Since the references have been selected to illustrate important points, the bibliographies, while thorough, are not complete. This volumes describes the observed performance and design problems of engine combustors of the principal types. These include combustor-inlet conditions; starting, acceleration, combustion limits, combustion efficiency, coke deposits, and smoke formation in turbojets; ram-jet performance; and afterburner performance and design.
Date: May 2, 1956

Adaptation of Combustion Principles to Aircraft Propulsion, Volume I, Basic Considerations in the Combustion of Hydrocarbon Fuels with Air

Description: The report summarizes source material on combustion for flight-propulsion engineers. First, several chapters review fundamental processes such as fuel-air mixture preparation, gas flow and mixing, flammability and ignition, flame propagation in both homogenous and heterogenous media, flame stabilization, combustion oscillations, and smoke and carbon formation. The practical significance and the relation of these processes to theory are presented. A second series of chapters describes the observed performance and design problems of engine combustors of the principal types. An attempt is made to interpret performance in terms of the fundamental processes and theories previously reviewed. Third, the design of high-speed combustion systems is discussed. Combustor design principles that can be established from basic considerations and from experience with actual combustors are described. Finally, future requirements for aircraft engine combustion systems are examined.
Date: April 1, 1955
Creator: Barnett, Henry C. & Hibbard, Robert R.

Adaptor for measuring principal strains with Tuckerman strain gage

Description: Report discussing an adapter which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.
Date: June 1943
Creator: Mcpherson, A E

Addition of heat to a compressible fluid in motion

Description: From Introduction: "The purpose of this report is to summarize, without extended proofs, the results of a study of a simplified model of nonadiabiatic, compressible fluid flow, both subsonic and supersonic, and to state these results in a form that will make them immediately useful in providing a theoretical background for current technical problems of high-speed combustion.
Date: February 1945
Creator: Hicks, Bruce L

Additional abstracts pertaining to seaplanes

Description: From Summary: "About 500 additional references pertaining to hydrodynamic design of seaplanes have been compiled, and the information is presented in the form of abstracts classified under six main headings:GENERAL INFORMATION, HYDROSTATICS, HYDRODYNAMICS, AERODYNAMICS, OPERATION, and RESEARCH. The compilation is an extension of NACA RM No. L6I13, entitled "Abstracts Pertaining to Seaplanes," by Jerold M. Bidwell and Douglas A. King. An author index and a subject index are included."
Date: March 9, 1948
Creator: Bidwell, J. M. & King, D. A.