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Accelerations in flight

Description: This report deals with the accelerations obtained in flight on various airplanes at Langley Field for the purpose of obtaining the magnitude of the load factors in flight and to procure information on the behavior of an airplane in various maneuvers. The instrument used in these tests was a recording accelerometer of a new type designed by the technical staff of the National Advisory Committee for Aeronautics. The instrument consists of a flat steel spring supported rigidly at one end so that the free end may be deflected by its own weight from its neutral position by any acceleration acting at right angles to the plane of the spring. This deflection is measured by a very light tilting mirror caused to rotate by the deflection of the spring, which reflected the beam of light onto a moving film. The motion of the spring is damped by a thin aluminum vane which rotates with the spring between the poles of an electric magnet. Records were taken on landings and takeoffs, in loops, spins, spirals, and rolls.
Date: 1921
Creator: Norton, F. H. & Allen, E. T.
Item Type: Report

Accelerations in flight

Description: This work on accelerometry was done at McCook Field for the purpose of continuing the work done by other investigators and obtaining the accelerations which occur when a high-speed pursuit airplane is subjected to the more common maneuvers. The accelerations obtained in suddenly pulling out of a dive with well-balanced elevators are shown to be within 3 or 4 per cent of the theoretically possible accelerations. The maximum acceleration which a pilot can withstand depends upon the length of time the acceleration is continued. It is shown that he experiences no difficulty under the instantaneous accelerations as high as 7.8 G., but when under accelerations in excess of 4.5 G., continued for several seconds, he quickly loses his faculties.
Date: 1925
Creator: Doolittle, J H
Item Type: Report

Accelerations in Landing with a Tricycle-Type Landing Gear

Description: In connection with the application of stable tricycle-type landing gears to transport airplanes, the question arises as to whether certain passengers may not experience relatively great accelerations in an emergency landing. Since the main landing wheels are behind the center of gravity in this type of gear, a hard-braked landing will cause immediate nosing down of the airplane and, when this motion is stopped due to the front wheel striking the ground, there will be some tendency for the rearmost passengers to be thrown out of their seats, The provided rough calculations are designed to show the magnitudes of the various reactions experienced in a severe landing under these circumstances.
Date: February 1937
Creator: Jones, Robert T.
Item Type: Report

Accelerometer design

Description: In connection with the development of an accelerometer for measuring the loads on airplanes in free flight a study of the theory of such instruments has been made, and the results of this study are summarized in this report. A portion of the analysis deals particularly with the sources of error and with the limitations placed on the location of the instrument in the airplane. The discussion of the dynamics of the accelerometer includes a study of its theoretical motions and of the way in which they are affected by the natural period of vibration and by the damping, together with a report of some experiments on the effect of forced vibrations on the record.
Date: 1921?~
Creator: Norton, F. H. & Warner, Edward P.
Item Type: Report

Accuracy of airspeed measurements and flight calibration procedures

Description: The sources of error that may enter into the measurement of airspeed by pitot-static methods are reviewed in detail together with methods of flight calibration of airspeed installations. Special attention is given to the problem of accurate measurements of airspeed under conditions of high speed and maneuverability required of military airplanes. (author).
Date: 1948
Creator: Huston, Wilber B
Item Type: Report

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
Item Type: Report

An accurate method of measuring the moments of inertia of airplanes

Description: 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
Item Type: Report

Acoustics of a nonhomogeneous moving medium.

Description: Theoretical basis of the acoustics of a moving nonhomogeneous medium is considered in this report. Experiments that illustrate or confirm some of the theoretical explanation or derivation of these acoustics are also included.
Date: February 1956
Creator: Blokhintsev, D I
Item Type: Report

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
Item Type: Report

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
Item Type: Report

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.
Item Type: Report

Adaptation of aeronautical engines to high altitude flying

Description: Issues and techniques relative to the adaptation of aircraft engines to high altitude flight are discussed. 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
Item Type: Report