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The Open Data Repository - an Open Science Platform for Long-Tail Research Data

Introduction: ‘Long-tail’ research is performed by individual PIs and small research teams, producing what are often highly diverse, but relatively small da-tasets that span a variety of traditional scientific disci-plines. ‘Long-tail’ research is a fundamental part of realizing NASA’s goals in planetary sciences and a key input feeding into mission life cycles. The ‘long-tail’ has traditionally lacked the resources (available to larg-er groups and missions) to overcome barriers inhibit-ing the adoption of open science practices, including lack of acknowledgment, time, money, guidance, ex-pertise, and trust in available platforms1. Here we show how the Open Data Repository’s (ODR) data publish-ing platform could help lower some of these barriers and accelerate the adoption of open-science practices in planetary science.

‘Long-tail’ research↗

NASA NTRS1957

An Investigation at Low Speed of the Spin Instability of Mortar-Shell Tails

An investigation was made in the Langley stability tunnel to study the influence of number of fins, fin shrouding, and fin aspect ratio on the spin instability of mortar-shell tail surfaces. It was found that the 12-fin tails tested spun less rapidly throughout the angle-of-yaw range than did the 6-fin tails and that fin shrouding reduced the spin encountered by a large amount.

Bird, John D.↗

NASA NTRS1972

Application of boron/epoxy reinforced aluminum stringers and boron/epoxy skid gear for the CH54B helicopter tail cone. Phase 2: Fabrication, inspection and flight test

A CH-54B Skycrane helicopter was fabricated with boron/epoxy reinforced stringers in the tail cone and boron/epoxy tubes in the tail skid. The fabrication of the tail cone was made with conventional tooling, production shop personnel, and no major problems. The flight test program includes a stress and vibration survey using strain gages and vibration transducers located in critical areas. The program to inspect and monitor the reliability of the components is discussed.

Welge, R. T.↗

NASA NTRS1972

Comet Tails of Type 2

A summary is presented of a theory for the head and tail regions of Type 2 (dust) comets, wherein dust particles having a wide distribution of sizes are assumed to be released from the comet nucleus in an essentially continuous manner in time during the period of distinctive cometary phenomena. The dust particles are assumed to be accelerated radially outward from the nucleus as a result of a drag interaction with the expanding gas in the comet head. In the tail region the only significant forces assumed to act on the dust particles are solar gravity and the force of solar radiation pressure. It is shown how results describing the surface density in the tail are obtained and how by matching calculated distributions with measured ones it is possible to determine the dust and head-gas emission rates as a function of time, the distribution of dust particle sizes, and the emission velocity from the inner head region as a function of particle size and time. The results of matching calculated density distributions with light intensity measurements from Comet Arend-Roland 1956h are summarized.

Probstein, R. F.↗

NASA NTRS1973

Supersonic aerodynamic characteristics of hypersonic low-wave-drag elliptical body-tail combinations as affected by changes in stabilizer configuration

An investigation has been made at Mach numbers from 1.50 to 4.63 to determine systematically the effects of the addition and position of outboard stabilizers and vertical- and vee-tail configurations on the performance and stability characteristics of a low-wave-drag elliptical body. The basic body shape was a zero-lift hypersonic minimum-wave-drag body as determined for the geometric constraints of length and volume. The elliptical cross section had an axis ratio of 2 (major axis horizontal) and an equivalent fineness ratio of 6.14. Base-mounted outboard stabilizers were at various dihedral angles from 90 deg to minus 90 deg with and without a single center-line vertical tail or a vee-tail. The angle of attack was varied from about minus 6 to 27 deg at sideslip angles of 0 and 5 deg and a constant Reynolds number of 4.58 x one million (based on body length).

Spencer, B., Jr.↗

NASA NTRS1973

Effect of nose shape and tail length on supersonic stability characteristics of a projectile

The effect of nose shape and tail length on the static stability of a fin-stabilized projectile has been investigated in the Langley Unitary Plan with tunnel at angles of attack to about 12 deg for a Mach number range from 1.5 to 2.5. The tests were made at a constant Reynolds number of 6.56 x 1,000,000 per meter. The results of the investigation showed that nose shape had no effect on the static stability. Increasing the tail length resulted in a progressively stabilizing tendency. However, only the 1.5-caliber-tail-length configuration was stable over the test angle-of-attack range at Mach number 1.5. This configuration was marginally stable or unstable at the higher Mach numbers, and the shorter configurations were unstable at all Mach numbers for either part of or the entire test angle-of-attack range.

Sawyer, W. C.↗

NASA NTRS1973

The effects of an autopilot on airplane responses to turbulence with emphasis on tail loads

An analytical study has been made to assess the loads developed on the horizontal tail of an autopilot-controlled rigid airplane flying in one-dimensional atmospheric turbulence. The root-mean-square values of rigid-airframe responses and tail-load responses were calculated at five flight conditions, and the behavior of these responses was observed in two autopilot modes: pitch-attitude-hold mode and altitude-control mode. It was found that pitch attitude and altitude can be controlled by the simple autopilot with acceptable or no increases in tail loads.

Perry, B., III↗

NASA NTRS1974

Vibrations of the earth's magnetic tail

The natural vibration period of the tail (regarded as bundle of magnetic line-of-force strings) and the characteristic time of recurrence of magnetospheric substorms are of the same order, suggesting the possibility of a relation between these phenomena. A model of the tail in the form of a plasma cylinder whose free boundary is immersed in the interplanetary plasma is examined. The nature of the natural oscillations of the tail excited by variations of the solar wind pressure is studied in this model. These vibrations have a total energy of approximately 10 to the 22nd power erg, which is sufficient to generate magnetospheric substorms.

Yershkovich, A. I.↗

NASA NTRS1975

Computer programs for calculating the static longitudinal aerodynamic characteristics of wing-body-tail configurations

Four computer programs developed to calculate the longitudinal aerodynamic characteristics of wing-body and wing-body-tail combinations are presented. The R1307 program is based on a linear method and is limited to the small range of angles of attack for which the lift and moment characteristics of wings and bodies are linear with angle of attack. The CRSFLW program is based on a crossflow method of predicting the forces and moments on bodies alone or wing-body combinations over a large angle of attack range. The SUBSON program predicts the longitudinal aerodynamic characteristics of wing-body-tail combinations at subsonic speeds and at angles of attack for which symmetrical pairs of vortices are shed from the body nose and the leading and side edges of the lifting surfaces. Program SUPSON predicts the longitudinal aerodynamic characteristics of wing-body-tail combinations at supersonic speeds in the same angle-of-attack range. A description of the use of each program, instructions for preparation of input, a description of the output, program listings, and sample cases for each program are included.

Mendenhall, M. R.↗

NASA NTRS1974

Tail structures far from the head of Comet Kohoutek. I

Two tail structures 0.1 AU from the head of Comet Kohoutek were photographed during January 1974. One was a wavy structure resembling a helix while the other was an irregular swan-like cloud. Both features were propagating down the tail at approximately 250 km/sec, and the observed speed is probably the phase speed. We discuss the physical origin of these structures and interpret the helix as a kink instability resulting from currents flowing along the tail axis.

Hyder, C. L.↗

NASA NTRS1975

Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

The present paper gives the results of an extensive analysis of plasma and magnetic-field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 earth radii downstream from earth. The principal observations are: (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma.

Walker, R. C.↗

NASA NTRS1975

Using the moon to probe the geomagnetic tail lobe plasma

We have detected the presence of plasma in the lobes of the geomagnetic tail from observations of magnetic induction in the moon forced by time variations of the earth's magnetotail lobe field. The magnitude of the moon's tangential electromagnetic transfer function when the moon is in the lobes of the geomagnetic tail is less than that when the moon is in the solar wind or geomagnetic tail plasma sheet. The tangential transfer function when the moon is in the magnetotail lobes decreases at frequencies above about 8 mHz due to finite wavelength effects. This shows that the waves in the magnetotail lobes which drive the lunar magnetic induction must have speeds far less than the speed of light and wavelengths comparable to the size of the moon.

Schubert, G.↗

NASA NTRS1975

Minimum Vertical Tail Drag

Tail size requirement calculations are presented for a vertical tail performing a coordinated turn reversal at corresponding load requirements with minimum tail drag.

Larrabee, E. E.↗

NASA NTRS1975

Experimental parametric studies of transonic T-tail flutter

Wind-tunnel tests of the T-tail of a wide-body jet airplane were made at Mach numbers up to 1.02. The model consisted of a 1/13-size scaled version of the T-tail, fuselage, and inboard wing of the airplane. Two interchangeable T-tails were tested, one with design stiffness for flutter-clearance studies and one with reduced stiffness for flutter-trend studies. Transonic antisymmetric-flutter boundaries were determined for the models with variations in: (1) fin-spar stiffness, (2) stabilizer dihedral angle (-5 deg and 0 deg), (3) wing and forward-fuselage shape, and (4) nose shape of the fin-stabilizer juncture. A transonic symmetric-flutter boundary and flutter trends were established for variations in stabilizer pitch stiffness. Photographs of the test configurations are shown.

Ruhlin, C. L.↗

NASA NTRS1976

Wind tunnel investigation of supersonic wing-tail flutter

A flutter model, consisting of a wing, horizontal tail, and splitter plate/fuselage mechanism, was tested in a 4-foot transonic tunnel in the Mach number range 1.1 to 1.3. Two types of flutter were encountered during the testing: a wing-tail flutter bending-torsion flutter mode. The wing-tail flutter speed was found to be a minimum at M = 1.2 for the configuration tested. Recorded model test data were digitized for a power spectral density (PSD) analysis and Random Decrement (Randomdec) analysis. Comparisons between the frequency and damping obtained from the PSD plots and the Randomdec signatures agreed very well. A limited flutter analysis was conducted using a Mach box unsteady aerodynamics method which accounted for interference and airfoil thickness. Analytical comparisons with experimental flutter speeds agreed well. The analyses assuming zero thickness predicted flutter speeds higher than those measured, ranging from 1 percent at M = 1.12 to 8 percent at M = 1.28. With the airfoil thickness included, the correlation was improved such that predicted flutter speeds for all cases investigated were within 2 percent of experimental speeds.

Huttsell, L. J.↗

NASA NTRS1976

Plasma irregularities in the comet's tail

Scintillation theory is invoked to explain fluctuations in radio intensity observed during occultation of the extragalactic radio source PKS 2025-15 by the plasma tail of comet 1973 XII on Jan. 5, 1975. Plasma irregularities and turbulence in the tail of the comet (Kohoutek 1973f) are fitted to a Gaussian spectrum and to a Kolmogorov power-law spectrum in analyzing the scintillation data. The rms fluctuation of electron density in the cometary tail is reported at 80 electrons per cu mm, the inner scale of the fluctuation at 800 km, and the largest scale of fluctuation at possibly 400,000 km. A hump in the comet power-law spectrum is noted. Use of the power spectrum of electron density fluctuations to predict the power spectrum of magnetic field fluctuations for irregularities associated with hydromagnetic turbulence is recommended.

Lee, L. C.↗

NASA NTRS1978

The flute instability as the trigger mechanism for disruption of cometary plasma tails

The sporadic disruption of the plasma tails of some comets has recently been explained to be caused by magnetic-field-line reconnection in the cometary ionospheres due to magnetic-sector-boundary traversals. An alternative model is proposed in which the tail disruption is the end result of compression of the cometary ionosphere by high-velocity solar-wind streams, triggering the flute instability in the marginally stable tangential-discontinuity surface which separates the cometary ionosphere from the solar-wind plasma. According to the proposed model, the tail-disruption events could occur at all heliographic latitudes, whereas the Niedner-Brandt (1978) model should predict that these events are restricted to low heliographic latitudes in view of the present understanding of the sector structure of the heliosphere. Consequently, the high-latitude disruption events observed seem to present a difficulty for the latter model.

Ip, W.-H.↗

NASA NTRS1979

Aircraft wake flow effect and horizontal tail buffet

As part of a program to investigate the fluctuating pressure distribution and response behavior of a fighter aircraft in transonic maneuver, an F-5A scale model has previously been tested in an 11-ft transonic wind tunnel. The model, with a number of static and dynamic pressure transducers imbedded in the lifting surfaces was tested at various angles of attack up to 16 deg. In this paper, test results of particular interest to wake flow and horizontal tail buffet are described. It is shown that the dynamic pressure data on the tail surface at the specified flight conditions serve to determine the local dynamic loads. They also influence the control performance of the aircraft under maneuver conditions where buffet is encountered. The data presented demonstrate a number of contributing factors that affect the tail dynamic pressures in the transonic regime.

Hwang, C.↗