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  • Other Sources  (5)
  • AERODYNAMICS  (3)
  • Lunar and Planetary Exploration  (2)
  • 1990-1994  (2)
  • 1975-1979  (3)
  • 1
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    Augmenting ejector endwall effects (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Rectangular inlet ejectors which had multiple hypermixing nozzles for their primary jets were investigated for the effects of endwall blowing on thrust augmentation performance. The ejector configurations tested had both straight wall and active boundary layer control type diffusers. Endwall flows were energized and controlled by simple blowing jets suitably located in the ejector. Both the endwall and boundary layer control diffuser blowing rates were varied to determine optimum performance. High area ratio diffusers with insufficient endwall blowing showed endwall separation and rapid degradation of thrust performance. Optimized values of diffuser boundary layer control and endwall nozzle blowing rates in an ejector augmenter were shown to achieve high levels of augmentation performance for maximum compactness.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 253-271
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Analytical study of a free-wing/free-trimmer concept (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The free-wing/free-trimmer is a NASA-Conceived extension of the free-wing concept intended to permit the use of high-lift flaps. Wing pitching moments are balanced by a smaller, external surface attached by a boom or equivalent structure. The external trimmer is, itself, a miniature free wing, and pitch control of the wing-trimmer assembly is effected through a trailing-edge control tab on the trimmer surface. The longitudinal behavior of representative small free-wing/free-trimmer aircraft was analyzed. Aft-mounted trimmer surfaces are found to be superior to forward trimmers, although the permissible trimmer moment arm is limited, in both cases, by adverse dynamic effects. Aft-trimmer configurations provide excellent gust alleviation and meet fundamental stick-fixed stability criteria while exceeding the lift capabilities of pure free-wing configurations.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2946
    Format: application/pdf
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  • 3
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    Extended analytical study of the free-wing/free-trimmer concept (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The free wing/free trimmer concept was analytically studied in order to: (1) compare the fore and aft trimmer configurations on the basis of equal lift capability, rather than equal area; (2) assess the influence of tip mounted aft trimmers, both free and fixed, on the lateral directional modes and turbulence responses; (3) examine the feasibility of using differential tip mounted trimmer deflection for lateral control; (4) determine the effects of independent fuselage attitude on the lateral directional behavior; and (5) estimate the influence of wing sweep on dynamic behavior and structural weight. Results indicate that the forward trimmer concept is feasible with the reduced size examined, but it remains inferior to the aft trimmer in every respect except structural weight. Differential motion of the aft trimmer is found to provide powerful lateral control; while the effect of fuselage deck angle is a reduction of the dutch roll damping ratio for nose-down attitudes.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3135
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Evidence for Day-to-Night Ion Transport at Low Solar Activity in the Venus Pre-Dawn Ionosphere (1993)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: Periapsis of the Pioneer Venus spacecraft dropped below 180 km on August 28, 1992 near midnight, and 42 orbits of low altitude data at moderately low solar activity in the pre-dawn sector were obtained before contact was lost to the spacecraft in October, 1992. Through a combination of analysis of data from the PV orbiter ion mass spectrometer (OIMS) and modeling, we consider here what can be learned about the relative importance of plasma transport from the dayside and electron precipitation in maintaining the nightside ionosphere during the re-entry period. In particular, we examine here the atomic ion density profiles. We compute the average peak density of O(+) as a function of solar zenith angle and determine what fluxes of atomic ions or precipitating electrons would be necessary to produce those values. We then compare model calculations of the ion densities to those observed during the re-entry period. We find that the low solar activity nightside ionosphere shows evidence of significant day-to-night plasma transport.
    Keywords: Lunar and Planetary Exploration
    Type: Paper 93GL02422 , Geophysical Research Letters. Selected Papers on Pioneer Venus Orbiter: Entry Phase; 20; 23; 2739-2742; NASA-TM-112700
    Format: text
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  • 5
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    Evidence for Day-to-Night Ion Transport at Low Solar Activity in the Venus Pre-Dawn Ionosphere (1993)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: Periapsis of the Pioneer Venus spacecraft 2 dropped below 180 km on August 28, 1992 near midnight, and 42 orbits of low altitude data at moderately low solar activity in the pre-dawn sector were obtained before contact was lost to the spacecraft in October, 1992. Through a combination of analysis of data from the PV orbiter ion mass spectrometer (OIMS) and modeling, we consider here what can be learned about the relative importance of plasma transport from the dayside and electron precipitation in maintaining the nightside ionosphere during the re-entry period. In particular, we examine here the atomic ion density profiles. We compute the average peak density of O(+) as a function of solar zenith angle and determine what fluxes of atomic ions or precipitating electrons would he necessary to produce those values. We then compare model calculations of the ion densities to those observed during the re-entry period. We find that the low solar activity nightside ionosphere shows evidence of significant day-to-night plasma transport.
    Keywords: Lunar and Planetary Exploration
    Type: NASA-CR-204705 , NAS 1.26:204705 , Paper-93GL02422 , Geophysical Research Letters (ISSN 0094-8534); 20; 23; 2739-2742
    Format: text
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