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  • 1
    Electronic Resource
    Electronic Resource
    Haloaldehyde polymers, 12Part 11: cf.8.. Preparation and polymerization of bromodifluoroacetaldehyde (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 633-647 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bromodifluoroacetaldehyde (5) was prepared from methyl bromodifluoroacetate (4) by reduction with lithium aluminium hydride. 4 was in turn prepared by bromination of chlorotrifluoroethylene (1) and treatment of the resulting 1,2-dibromo-1-chlorotrifluoroethane (2) with fuming H2SO4 and HgO. 5, properly purified, could be polymerized with anionic and cationic initiators to poly[oxy-2-(bromodifluoro)ethylidene] (12). Certain initiators produce partially or entirely amorphous soluble 12 of relatively low molecular weight. Most polymers, however, are insoluble, crystalline, and presumably isotactic. Thermal vacuum degradation of the polymers 12 gave monomer 5 in essentially quantitative yield. The thermal stability of polymers can significantly be improved by endcapping or treating with agents which replace unstable end groups. The ceiling temperature of the polymerization of 5 was determined to be +48°C. 5 was copolymerized with trichloroacetaldehyde with cationic or anionic initiators to copolymers containing predominantly units of 5. 5 could also be copolymerized with phenyl isocyanate to a polymer containing oxycarbamido linkages.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800307
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Flight investigation of the response of a helicopter to the trailing vortex of a fixed-wing aircraft (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A flight investigation was conducted to quantitatively determine the response of a medium-weight helicopter to the trailing-vortex system of a fixed-wing aircraft. Flight tests and analytical tools were both utilized in the investigation. The flight tests involved an extensively instrumented UH-1H helicopter and a C-54 aircraft. Penetrations of the vortex system by the UH-1H were made at the following nominal conditions: the C-54 flew at 5500 feet altitude at a nominal gross weight of 58,000 pounds and an indicated airspeed of 115 knots in a cruise configuration. The UH-1H, nominally 7200 pounds gross weight, flew at 60 knots indicated airspeed during the penetrations at separation distances of 6.64 nautical miles to 0.42 nautical mile between aircraft. In general, the data analyzed for the above tests indicated that no unsafe penetration occurred. Further, penetrating vehicle attitude changes and structural loads were nominal. In addition, the response of the helicopter did not change appreciably with decreased separation distance.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Atmospheric Flight Mechanics Conference; Jun 07, 1976 - Jun 09, 1976; Arlington, TX
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Flight-test experience of a helicopter encountering an airplane trailing vortex (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper presents results of a flight-test experiment of a UH-1H helicopter encountering the vortex wake of a C-54 airplane. The helicopter was instrumented to record the pilot control inputs, determine the upset experience, and measure critical loads within the rotor system. During the flight-test program 132 penetrations of the vortex wake were made by the helicopter at separation distances from 3/8 to 6-1/2 nautical miles. Test results indicated that the helicopter upsets and the vortex induced blade loads experienced were minimal and well within safe limits. The upsets were very mild when compared to a typical response of a small airplane to the vortex wake of the C-54 airplane.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Annual National Forum of the American Helicopter Society; May 10, 1976 - May 12, 1976; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Some results of the testing of a full-scale Ogee tip helicopter rotor; acoustics, loads, and performance (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Full-scale tests were utilized to investigate the effect of the Ogee tip on helicopter rotor acoustics, performance, and loads. Two facilities were used for this study: the Langley whirl tower and a UH-1H helicopter. The test matrix for hover on the whirl tower involved thrust values from 0 to 44,480 N (10,000 lbs) at several tip Mach numbers for both standard and Ogee rotors. The full-scale testing on the UH-1H encompassed the major portion of the flight envelope for that aircraft. Both near-field acoustic measurements as well as far-field flyover data were obtained for both the Ogee and standard rotors. Data analysis of the whirl-tower test shows that the Ogee tip does significantly diffuse the tip vortex while providing some improvement in hover performance. Flight testing of both rotors indicates that the strong impulsive noise signature of the standard rotor can be reduced with the Ogee rotor. Forward flight performance was significantly improved with the Ogee configuration for a large number of flight conditions. Further, rotor control loads and vibrations were reduced through use of this advanced tip rotor.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 77-1340 , Aeroacoustics Conference; Oct 03, 1977 - Oct 05, 1977; Atlanta, GA
    Format: text
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    NASA TECHNICAL REPORTS
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