Width of the Turbulent Trail behind a Hypervelocity Sphere

Slattery, R. E.; Clay, W. G.

doi:10.1063/1.1706195

Cited by 25 publications

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“…For an elliptical meridian section of equatorial semiaxis a and polar semiaxis b, it is easily found that N = aVl -e 2 sin 2 <p (20) where e b 2 /a is the eccentricity. For the international ellipsoid, Ref.…”

Section: Earth Shape and Gravity Functionsmentioning

confidence: 98%

“…From Eq. (20), Np and N^ can be found by differentiation. All three functions might be rearranged or approximated to facilitate their representation in the navigation computer, but the most suitable modifications would depend to such an extent on the nature of the computer and the required accuracy that they are not considered here.…”

Section: Earth Shape and Gravity Functionsmentioning

confidence: 99%

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Elementary Derivation of General Equations for Terrestrial Inertial Navigation

Schultz¹

1962

Journal of the Aerospace Sciences

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The equations to be represented in the computer of an inertial navigation system for use near the surface of the earth are derived by elementary methods, and a block diagram of the computer is presented. No restrictions are placed on the nature of the earth's gravity field and only minor restrictions on the shape of the earth. The shape and gravity field of the earth are discussed and specialization of the equations and block diagram is made for the case where the earth and gravity field are assumed to have axial symmetry.a a b e Symbols = arbitrary vector = true time derivative of A = apparent time derivatives = magnitude of A = components of A = indicated acceleration vector = magnitude of indicated acceleration; also equatorial radius of the earth = polar radius of the earth = eccentricity of elliptical meridian section of earth G = acceleration due to gravity (mass attraction only) g = apparent acceleration due to gravity (including centrifugal force) h = altitude N = function describing size and shape of earth N

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Section: Earth Shape and Gravity Functionsmentioning

confidence: 98%

Section: Earth Shape and Gravity Functionsmentioning

confidence: 99%

Elementary Derivation of General Equations for Terrestrial Inertial Navigation

Schultz¹

1962

Journal of the Aerospace Sciences

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“…Zur Untersuchung von ebenen Flammen ist ein scharf-fokussierendes Bild 9. Schlierenanordnung im Vakuum mit parallelem Strahlengang [37]. Bezeichnungen s. Bild 8.…”

Section: Flammenuntersuchungenunclassified

Sichtbarmachung von Strömungen IV. Das Schlierenverfahren

Wuest¹

1967

tm - Technisches Messen

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ATM) Archiv für technisches Messen Blatt V 144-5 (April 1967) 81 V Bild 2. Schlierenaufnahme bei einem Gasgemisch (Ausblasen von Kohlensäure entgegen einer Luftströmung). schiede auftreten. Bild 2 zeigt als Beispiel für den letzten Fall die Umströmung einer Flügelvorderkante, aus der Kohlensäure ausgeblasen wird. In vielen Fällen ist es vorteilhaft, die Schlierenblende durch einen Graukeil zu ersetzen, weil auch die Bildschärfe bei starken Ablenkungen verbessert werden ® © © @ Bild 1. Toeplersches Schlierenverfahren. 5 Lichtquelle, Ml, M2 Konkavspiegel, Κ Meßkammer (der gestrichelte Keil deutet einen Dichtegradienten an), Β Bild der Lichtquelle und Schlierenblende, Q Bild der Meßkammer. Bild 3a-d. Verschiedene Schlierenanordnungen, a) Mit zwei Linsen, b), c) mit einer Linse, d) mit doppeltem Lichtdurchgang. Bezeichnungen s. Bild 1.

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“…As indicated on Figure 9, the diffuse-scattering curve (aDs)•.ax plotted for comparison with observation was based on a range cell thickness of 230 meters (corresponding to an effective pulse width of 1.5 psec), and on a wake width of 30 meters. It may be noted that 30 meters is the geometrical width to be expected of a turbulent wake at a distance of 2000 diameters behind a sphere of 3-meter diameter at hypersonic speeds [Slattery and Clay, 1961;Lees and Hromas, 1962]. It is, therefore, also approximately the width to be expected of a turbulent wake at a distance of about 4.2 km behind the MA-6 Mercury capsule, which had an over-all diameter of 2 meters but was a somewhat blunter object than a sphere of the same diameter [NASA, 1962].…”

Section: Part Of the Intensity-modulated Range-time Record From The Fmentioning

confidence: 99%

Radio echoes from a manned satellite during re-entry

Lin¹

1962

J. Geophys. Res.

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The ionized trails produced during re‐entry by the MA‐6 Mercury capsule carrying Lt. Col. John Glenn in his first orbital flight on February 20, 1962, were observed from San Salvador Island (Bahama Island Group), approximately 370 nautical miles uprange from the landing point. The apparatus employed was an omnidirectional pulsed radar (of 30.25 Mc/s carrier frequency) similar to those employed by McKinley and Millman in the study of meteor echoes. When the Mercury capsule was passing over the vicinity of the observation station at about 14h 33m EST, five clearly separated ionized trails were observed. The most prominent trail, which may be identified with the wake of the main capsule, was visible to the radar for a total duration of about 20 sec and displayed an equivalent isotropic scattering cross section of about 106 square meters at its peak. The other four trails, which were probably due to fragments of the disintegrating retro‐rocket package reported by Glenn, showed only short duration glints (of the order of one second) characteristic of the smooth, rapidly decaying trails of small meteors. Though some of the fine structure of the long duration, scintillating echo from the main capsule trail is not yet understood, the over‐all characteristics of the trail can be accounted for by a combination of high light from a strongly reflecting front segment of the ionized wake, which appeared electromagnetically smooth to the 10‐meter wavelength employed, and diffused scattering from a turbulent rear segment of the wake, which appeared rough to the wavelength. The fact that the main capsule trail appeared turbulent indicates a Reynolds number of less than 105 (based on the velocity and diameter of the MA‐6 capsule, and on the ambient air density) for transition from laminar to turbulent flow in the wake. The appearance of a leading edge echo about two miles ahead of the strongly scattering turbulent wake also suggested the existence of a ‘photoionization halo’ around the capsule due to ultraviolet radiation from the bow shock wave. From these results, some conclusions concerning the origin of instantaneous meteoric head echo may be inferred.

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Width of the Turbulent Trail behind a Hypervelocity Sphere

Cited by 25 publications

References 0 publications

Elementary Derivation of General Equations for Terrestrial Inertial Navigation

Elementary Derivation of General Equations for Terrestrial Inertial Navigation

Sichtbarmachung von Strömungen IV. Das Schlierenverfahren

Radio echoes from a manned satellite during re-entry

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