A NASA/University/Industry Consortium for Research on Aircraft Ice Protection

From 1982 through 1987, an unique consortium was functioning which involved government (NASA), academia (Wichita State Univ.) and twelve industries. The purpose was the development of a better ice protection systems for aircraft. The circumstances which brought about this activity are described, the formation and operation recounted, and the effectiveness of the ventue evaluated

An Absorption Band of Formaldoxime at lambda9572

The third harmonic of the O [Single Bond] H band in formaldoxime vapor has been found to lie at lambda9572 (10,444.1 cm^—1) and under high dispersion has been resolved and found to resemble a parallel band of a symmetric rotator. Owing to the weakness of the lines near the center of the band a definitely unique rotational analysis could not be made but the harmonic mean of the two larger moments of inertia appears to lie between the limits 73.3 and 76.6×10^—40 g cm^2. The hydroxyl hydrogen does not rotate freely and indeed its torsional oscillation appears not to have a very low frequency. It is not possible to locate this hydrogen uniquely until other parameters of the molecule have been determined by electron diffraction. The possible effect of resonance on the O [Single Bond] H frequency is discussed

Structure of the O[Single Bond]H Bands in the Vapors of Halogen Substituted Alcohols

In the study of the infra-red absorption of organic substances containing hydroxyl groups it has been found that the O-H bands sometimes occur as multiplets even though only one such group is present per molecule. This has been observed both in the spectra of vapors (1) and of solutions (2,3) though in the latter case less structure is resolvable in some instances. The phenomenon has been explained by saying that the hydroxyl hydrogen is not free to rotate around the C-O bond, but may be found in more than one position of potential minimum in which the O-H frequency may be somewhat different (1,4). Though this explanation appears plausible it has seemed desirable to investigate the matter further by a quantitative study of some relatively simple substances in the vapor phase. Consequently a series of halogen substituted alcohols has been investigated with interesting results

De-icing of the altitude wind tunnel turning vanes by electro-magnetic impulse

The Altitude Wind Tunnel at the NASA-Lewis facility is being proposed for a refurbishment and moderization. Two major changes are: (1) the increasing of the test section Mach number to 0.90, and (2) the addition of spray nozzles to provide simulation of flight in icing clouds. Features to be retained are the simulation of atmospheric temperature and pressure to 50,000 foot altitude and provision for full-scale aircraft engine operation by the exhausting of the aircraft combustion gases and ingestion of air to replace that used in combustion. The first change required a re-design of the turning vanes in the two corners downstream of the test section due to the higher Mach number at the corners. The second change threatens the operation of the turning vanes by the expected ice build-up, particulary on the first-corner vanes. De-icing by heat has two drawbacks: (1) an extremely large amount of heat is required, and (2) the melted ice would tend to collect as ice on some other surfaces in the tunnel, namely, the tunnel propellers and the cooling coils. An alternate de-icing method had been under development for three years under NASA-Lewis grants to the Wichita State University. This report describes the electro-impulse de-icing (EIDI) method and the testing work done to assess its applicability to wind tunnel turning vane de-icing. Tests were conducted in the structural dynamics laboratory and in the NASA Icing Research Tunnel. Good ice protection was achieved at lower power consumption and at a wide range of tunnel operations conditions. Recommendations for design and construction of the system for this application of the EIDI method are given

A new flow model for highly separated airfoil flows at low speeds

An analytical model for separated airfoil flows is presented which is based on experimentally observed physical phenomena. These include a free stagnation point aft of the airfoil and a standing vortex in the separated region. A computer program is described which iteratively matches the outer potential flow, the airfoil turbulent boundary layer, the separated jet entrainment, mass conservation in the separated bubble, and the rear stagnation pressure. Separation location and pressure are not specified a priori. Results are presented for surface pressure coefficient and compared with experiment for three angles of attack for a GA(W)-1, 17% thick airfoil

Supersonic burning in separated flow regions

The trough vortex phenomena is used for combustion of hydrogen in a supersonic air stream. This was done in small sizes suitable for igniters in supersonic combustion ramjets so long as the boundary layer displacement thickness is less than 25% of the trough step height. A simple electric spark, properly positioned, ignites the hydrogen in the trough corner. The resulting flame is self sustaining and reignitable. Hydrogen can be injected at the base wall or immediately upstream of the trough. The hydrogen is introduced at low velocity to permit it to be drawn into the corner vortex system and thus experience a long residence time in the combustion region. The igniters can be placed on a skewed back step for angles at least up to 30 deg. without affecting the igniter performance significantly. Certain metals (platinum, copper) act catalytically to improve ignition

The N[Single Bond]H Harmonic Bands of Pyrrole at lambda9900, and the Structure of the Pyrrole Molecule

In their study of the infra-red absorption of organic substances in carbon tetrachloride solution Wulf and Liddell (1) found that the strong second harmonic N-H band of pyrrole is accompanied by a weak satellite which lies approximately 50 cm^-1 to the long wave side and has roughly one-twentieth the intensity of the main band. The main band has been attributed by Pauling (2) to a planar pyrrole molecule and the weak satellite to a second molecular species in which the imino hydrogen lies out of the plane of the other atoms

Stochastic Dominance Analysis of iShares

Country indices as represented by iShares exhibit non-normal return distributions with both skewness and kurtosis. Davidson and Duclos (2000) and Memmel (2003) provide procedures for determining the statistical significance of stochastic dominance measures and the Sharpe Ratio, respectively. This study uses these refinements to compare the performance of 18 country market indices. The iShares are indistinguishable when using the Sharpe Ratio as no significant differences are found. In contrast, stochastic dominance procedures identify dominant iShares. Although the results vary over time, stochastic dominance appears to be both more robust and discriminating than the CAPM in the ranking of the iShares.Stochastic dominance; Sharpe ratio; skewness; country index funds

Divergence of opinion and risk : an empirical analysis of the Ex Ante beliefs of institutional investors

Bibliography: p. [24-25

Electro-impulse de-icing testing analysis and design

Electro-Impulse De-Icing (EIDI) is a method of ice removal by sharp blows delivered by a transient electromagnetic field. Detailed results are given for studies of the electrodynamic phenomena. Structural dynamic tests and computations are described. Also reported are ten sets of tests at NASA's Icing Research Tunnel and flight tests by NASA and Cessna Aircraft Company. Fabrication of system components are described and illustrated. Fatigue and electromagnetic interference tests are reported. Here, the necessary information for the design of an EIDI system for aircraft is provided