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Howell, R. R.

Publications and source records attributed to Howell, R. R..

30 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Speckle interferometry of molecular cloud sources at 4.8 microns

The spatial structure at 4.8 microns has been observed in W3-IRS 5, Mon R2-IRS 3, and S 140-IRS 1, the first two of which are clearly double. In addition, for four compact sources, low upper limits can be set to the angular diameters which are near those for blackbodies having the same fluxes and color temperatures observed for those sources. With a factor-of-2 higher-resolution, one may be able to distinguish between thermal emission or reddening as the source of the observed spectral shape.

Dyck, H. M.↗
NASA NTRS1982

Galileo Institute for Astronomy (IFA) charge-coupled device (CCD) system

A fully portable self-contained charge-coupled device system has been constructed for shared use with the Galileo Project Imaging Team. The detector currently incorporated in the system is a Texas Instruments 500 x 500 three-phase CCD that has been thinned to operate in the backside illuminated mode. The detector and camera mainframe electronics were provided by the Jet Propulsion Laboratory. The support electronics and control interfaces necessary to operate the mainframe were constructed. The data system, which is built around a DeAnza Visacom VC-5000 Image Processor with an imbedded LSI-11 minicomputer, was also integrated. The capability to do image processing in real-time at the telescope has proved to be extremely valuable. The overall system read noise has been measured at 25 electrons. Full-well capacity is 40,000 electrons. Some results from laboratory tests and initial observing runs at the Mauna Kea 2.2-m telescope are presented.

Hlivak, R. J.↗
NASA NTRS1981

The National Transonic Facility: Review and status report

The status of the National Transonic Facility (NTF) Project and some of the pertinent performance characteristics and features of the new wind tunnel are reviewed. The liquid nitrogen supply, current views of user cost, and the activation schedule are discussed.

Howell, R. R.↗
NASA NTRS1980

The National Transonic Facility - Status and operational planning

The National Transonic Facility is scheduled to be completed in 1982. Several technical concerns remain, including thermal stress constraints which may limit the rate at which temperatures can be changed, seal performance in the cryogenic environment, and the tunnel process controls which could affect data acquisition rate. The current design affords the capability of dealing with all these concerns if they become problems. The outstanding instrument need is a real-time model surface deformation measurement system. Finally, an examination of the occupancy cost and the cost of liquid nitrogen for high Reynolds number tests indicates that operating costs should not be an inhibiting factor in the use of the facility.

Howell, R. R.↗
NASA NTRS1980

A system for model access in tunnels with an unbreathable test medium

In many specialty wind tunnels, test gases other than ambient air are used to meet special testing requirements. A typical example is the use of freon as the test gas to achieve a realistic density ratio between gas and model for exploring flutter stability boundaries. Another example is the use of pressurized air to elevate the stream density and enhance Reynolds number or dynamic pressure simulation. Such specialty tunnels require a system of access o the model which will allow services and changes to the model without exposing personnel to the unnatural and perhaps hostile environment or requiring the venting and purging of the entire tunnel circuit. This paper will describe the plenum and model access systems for the forthcoming U.S. National Transonic facility where gaseous nitrogen (N2) at temperatures between 338 and 78 K and at pressures to 9 bars is used as the test medium. The operation at cold temperatures imposes some additional requirements which make the access systems more difficult to design and time consuming to operate than for conventional wind tunnels.

Howell, R. R.↗
NASA NTRS1976

The U.S. 2.5-Meter Cryogenic High Reynolds Number Tunnel

The U.S. 2.5-Meter Cryogenic High Reynolds Number Tunnel is a fan-driven transonic wind tunnel scheduled for operation in 1981. It will operate at Mach numbers from 0.1 to 1.2, stagnation pressures from 1 to 9 bars, and stagnation temperatures from 352 to 80 Kelvin. The maximum Reynolds number capability will be 120 million at a Mach number of 1.0 based on a reference length of 0.25 meter. This paper describes the basis for the conceptual approach, the engineering design including unique features, and the performance operating envelopes for the tunnel.

Howell, R. R.↗
NASA NTRS1976

The characteristics of the planned National Transonic Facility

The National Transonic Facility is a high Reynolds number transonic wind tunnel designed to satisfy the research and development needs of NASA, DOD, and industry. The facility design incorporates the cryogenic approach to achieving high Reynolds numbers with manageable model loads. By using temperature as a test variable, a unique capability to clearly separate aeroelastic, Reynolds number, and Mach number effects will be possible. This capability will open new horizons in transonic aerodynamic research. The tunnel design including unique features and operating envelopes is described. A brief overview of the general operating arrangement and the schedule for facility construction is presented.

Mckinney, L. W.↗