Engineering topics

Wessling, Francis C.

Publications and source records attributed to Wessling, Francis C..

13 records

NASA NTRS2001

Ground Based Experiments in Support of Microgravity Research Results-Vapor Growth of Organic Nonlinear Optical Thin Film

This work is specifically focused on explaining previous results obtained for the crystal growth of an organic material in a reduced gravity environment. On STS-59, in April 1994, two experiments were conducted with N,N-dimethyl-p-(2,2-dicyanovinyl) aniline (DCVA), a promising nonlinear optical (NLO) material. The space experiments were set to reproduce laboratory experiments that yielded small, bulk crystals of DCVA. The results of the flight experiment, however, were surprising. Rather than producing a bulk single crystal, the result was the production of two high quality, single crystalline thin films. This result was even more intriguing when it is considered that thin films are more desirable for NLO applications than are bulk single crystals. Repeated attempts on the ground to reproduce these results were fruitless. A second set of flight experiments was conducted on STS-69 in September 1995. This time eight DCVA experiments were flown, with each of seven experiments containing a slight change from the first reference experiment. The reference experiment was programmed with growth conditions identical to those of the STS-59 mission. The slight variations in each of the other seven were an attempt to understand what particular parameter was responsible for the preference of thin film growth over bulk crystal growth in microgravity. Once again the results were surprising. In all eight cases thin films were grown again, albeit with varying quality. So now we were faced with a phenomenon that not only takes place in microgravity, but also is very robust, resisting all attempts to force the growth of bulk single crystals.

Zugrav, M. Ittu↗

NASA NTRS2000

Modeling Specular Exchange Between Concentric Cylinders in a Radiative Shielded Furnace

The objective of this research is to develop and validate mathematical models to characterize the thermal performance of a radiative shielded furnace, the University of Alabama in Huntsville (UAH) Isothermal Diffusion Oven. The mathematical models are validated against experimental data obtained from testing the breadboard oven in a terrestrial laboratory environment. It is anticipated that the validation will produce math models capable of predicting the thermal performance of the furnace over a wide range of operating conditions, including those for which no experimental data is available. Of particular interest is the furnace core temperature versus heater power parametric and the transient thermal response of the furnace. Application to a microgravity environment is not considered, although it is conjectured that the removal of any gravity dependent terms from the math models developed for the terrestrial application should yield adequate results in a microgravity environment. The UAH Isothermal Diffusion Oven is designed to provide a thermal environment that is conducive to measuring the diffusion of high temperature liquid metals. In addition to achieving the temperatures required to melt a sample placed within the furnace, reducing or eliminating convective motions within the melt is an important design consideration [1]. Both of these influences are reflected in the design of the furnace. Reducing unwanted heat losses from the furnace is achieved through the use of low conductivity materials and reflective shielding. As evidenced by the highly conductive copper core used to house the sample within the furnace, convective motions can be greatly suppressed by providing an essentially uniform thermal environment. An oven of this design could ultimately be utilized in a microgravity environment, presumably as a experiment payload. Such an application precipitates other design requirements that limit the resources available to the furnace such as power, mass, volume, and possibly even time. Through the experimental and numerical results obtained, the power requirements and thermal response time of the breadboard furnace are quantified.

Schunk, Richard Gregory↗

NASA NTRS1996

Gravitational Effects on Closed-Cellular-Foam Microstructure

Polyurethane foam has been produced in low gravity for the first time. The cause and distribution of different void or pore sizes are elucidated from direct comparison of unit-gravity and low-gravity samples. Low gravity is found to increase the pore roundness by 17% and reduce the void size by 50%. The standard deviation for pores becomes narrower (a more homogeneous foam is produced) in low gravity. Both a Gaussian and a Weibull model fail to describe the statistical distribution of void areas, and hence the governing dynamics do not combine small voids in either a uniform or a dependent fashion to make larger voids. Instead, the void areas follow an exponential law, which effectively randomizes the production of void sizes in a nondependent fashion consistent more with single nucleation than with multiple or combining events.

Noever, David A.↗

NASA NTRS1993

Nickel metal hydride, a flight experiment

A nickel metal hydride battery was discharged at high rate in a microgravity environment. Data from the flight is compared to data taken on the earth's surface.

Fitzgerald, Edward A.↗

NASA NTRS1992

Design of multisample, multistep phase partitioning apparatus for use on Space Shuttle Spacelab, and Spacelab missions

Traditional separation techniques are inadequate for many new bioprocessing challenges. Innovative separation methods such as aqueous two phase partitioning are needed to perpetuate bioprocess commercialization. Aqueous two phase polymer partitioning systems provide a process for separating biological materials when combined with microgravity. An innovative space qualified apparatus developed for carrying out separations by partitioning in immiscible polymer systems under mirogravity conditions is described. The apparatus offers an innovative approach to low gravity bioseparations in general and phase partitioning in particular. These capabilities support NASA's interest in serving the biotechnology research community and providing quantitative data in the gravity dependent components of separation processes.

Deuser, Mark S.↗

NASA NTRS1991

Consort 3 flight experiments

The third sounding rocket payload in the Consort program was launched from the White Sands Missile Range on May 16, 1990. It carried 12 experiments designed to investigate materials processes in low gravity. All of the experiments were reflights from the Consort 2 payload that was launched on November 1989 but failed to achieve microgravity because of a malfunction in the launch vehicle. Four national Centers for the Commercial Development of Space participated in the mission. The payload included five experiments and two accelerometer systems that flew on Consort 1 and seven new experiments, designed and developed since Consort 1. Experiments from Consort 1 incorporated hardware modifications and changes in experimental parameters based on mission results. The new experiments covered a variety of polymeric and biological investigations. A new power distribution and control system designed to provide discrete, computer-supervised, experiment power monitoring and control was flight qualified on Consort 3. Consort 3 featured very late access (3-5 h before launch vs 27-30 h for Consort 1) for installation of sensitive biological specimens. The integrated payload and mission sequence of events are described. Changes in the Consort 1 experiments are defined and the objectives, methods, and expectations for new experiments are discussed.

Wessling, Francis C.↗

NASA NTRS1991

Sounding rocket lessons learned

Programmatic, applicatory, developmental, and operational aspects of sounding rocket utilization for materials processing studies are discussed. Lessons learned through the experience of 10 sounding rocket missions are described. Particular attention is given to missions from the SPAR, Consort, and Joust programs. Successful experiments on Consort include the study of polymer membranes and resins, biological processes, demixing of immiscible liquids, and electrodeposition.

Wessling, Francis C.↗

NASA NTRS1991

Consort and Joust sounding rocket missions

The two suborbital rocket programs are described in terms of their common objective of examining commercial applications of materials processing under microgravitational conditions. The sounding rocket programs have unique launch-service capabilities but provide essentially interchangeable payload accommodations. Major differences include longer low gravity times and larger payload volume for the Joust rocket, spin stabilization and land recovery for the Consort rocket, and faster ascent and reentry accelerations for the Joust rocket. A summary of previous and planned experiments for the rocket programs is given which includes studies of the morphology and strength of elastomer-modified epoxy resins, electrodeposition studies, the demixing of immiscible polymers, foam formation, and polymer experiments. These and other experiments can be facilitated by the microgravity time available on flights of the two sounding rockets.

Wessling, Francis C.↗

NASA NTRS1990

Foam formation in low gravity

An apparatus that produced the first polyurethane foam in low gravity has been described. The chemicals were mixed together in an apparatus designed for operation in low gravity. Mixing was by means of stirring the chemicals with an electric motor and propeller in a mixing chamber. The apparatus was flown on Consort 1, the first low-gravity materials payload launched by a commercial rocket launch team. The sounding rocket flight produced over 7 min of low gravity during which a polyurethane spheroidal foam of approximately 2300 cu cm was formed. Photographs of the formation of the foam during the flight show the development of the spheroidal form. This begins as a small sphere and grows to approximately a 17-cm-diam spheroid. The apparatus will be flown again on subsequent low-gravity flights.

Wessling, Francis C.↗

NASA NTRS1990

Low gravity investigations in suborbital rockets

Two series of suborbital rocket missions are outlined which are intended to support materials and biotechnology investigations under microgravity conditions and enhance commercial rocket activity. The Consort series of missions employs the two-stage Starfire I rocket and recovery systems as well as a payload of three sealed or vented cylindrical sections. The Consort 1 and 2 missions are described which successfully supported six classes of experiments each. The Joust program is the second series of rocket missions, and the Prospector rocket is employed to provide comparable payload masses with twice as much microgravity time as the Consort series. The Joust and Consort missions provide 6-8 and 13-15 mins, respectively, of microgravity flight to support such experiments as polymer processing, scientific apparatus testing, and electrodeposition.

Wessling, Francis C.↗

NASA NTRS1989

Consort 1 sounding rocket flight

This paper describes a payload of six experiments developed for a 7-min microgravity flight aboard a sounding rocket Consort 1, in order to investigate the effects of low gravity on certain material processes. The experiments in question were designed to test the effect of microgravity on the demixing of aqueous polymer two-phase systems, the electrodeposition process, the production of elastomer-modified epoxy resins, the foam formation process and the characteristics of foam, the material dispersion, and metal sintering. The apparatuses designed for these experiments are examined, and the rocket-payload integration and operations are discussed.

Wessling, Francis C.↗

NASA NTRS1989

Consort 1 flight results - A synopsis

All six experiments performed onboard Consort 1, the first low gravity materials processing payload to be launched by a commercially licensed rocket in the U.S., are evaluated. The six experiments were carried out as planned, during approximately seven minutes of suborbital, low gravity flight and returned in excellent condition within four hour of launch. Nearly 150 physical samples supported by measurements and photographs made during the flight were taken for analysis. The rocket flight and payload configuration is described, along with experiment objectives, methods, results, and conclusions.

Wessling, Francis C.↗

NASA NTRS1987

Phase partitioning, crystal growth, electrodeposition and cosmic ray experiments in microgravity

Five experiments are contained in one Get Away Special Canister (5 cu ft). The first utilizes microgravity to separate biological cells and to study the mechanism of phase partitioning in 12 separate cuvettes. Two experiments are designed to grow organic crystals by physical vapor transport. One experiment consists of eight electroplating cells with various chemicals to produce surfaces electroplated in microgravity. Some of the surfaces have micron sized particles of hard materials co-deposited during electrodeposition. The fifth experiment intercepts cosmic ray particles and records their paths on photographic emulsions. The first four experiments are controlled by an on-board C-MOS controller. The fifth experiment is totally passive. These are the first in Space. Their purpose is to create new commercial products with microgravity processing.

Wessling, Francis C.↗