Engineering topics

Love, Wendell L.

Publications and source records attributed to Love, Wendell L..

4 records

NASA NTRS1993

A ceramic matrix composite thermal protection system for hypersonic vehicles

The next generation of hypersonic vehicles (NASP, SSTO) that require reusable thermal protection systems will experience acreage surface temperatures in excess of 1100 C. More important, they will experience a more severe physical environment than the Space Shuttle due to non-pristine launching and landing conditions. As a result, maintenance, inspection, and replacement factors must be more thoroughly incorporated into the design of the TPS. To meet these requirements, an advanced thermal protection system was conceived, designated 'TOPHAT'. This system consists of a toughened outer ceramic matrix composite (CMC) attached to a rigid reusable surface insulator (RSI) which is directly bonded to the surface. The objective of this effort was to evaluate this concept in an aeroconvective environment, to determine the effect of impacts to the CMC material, and to compare the results with existing thermal protection systems.

Riccitiello, Salvatore R.↗

NASA NTRS1992

Arc-jet tests of coated carbon-carbon materials

The testing of coated carbon-carbon materials at high temperature in a nonequilibrium arc-driven environment is examined. Material specimens were exposed to high energy supersonic air exhausting from the NASA-Ames Research Center's 20-MW arc-jet facility. The materials were heated to required temperatures with arc-heated air for specified lengths of time. A total of 23 models were tested in two groups. In the first group of 19 samples, there were several samples that survived low test conditions and several more that survived intermediate test conditions that provided surface temperatures up to 3850 deg Rankine, but none survived when the surface temperature exceeded 4000 deg Rankine. The last four test samples with their higher surface temperatures did not fully survive either if the survival criterion is that the material must be reusable after the test.

Sheldahl, Robert E.↗

NASA NTRS1992

Evaluation of 2D ceramic matrix composites in aeroconvective environments

An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.

Riccitiello, Salvatore R.↗

NASA NTRS1991

Effects of aeroconvective environments on 2D reinforced ceramic matrix composites

The effect of aeroconvective heating environment similar to that observed a spacecraft ascent or reentry from orbit, on the performance of a commercial carbon-reinforced ceramic matrix material specimens of two configurations (orthotropic and quasi-isotropic), fabricated by the Societe Europenne Propulsion (SEP) process was investigated using the NASA Ames Research Center 20 Megawatt Panel Test facility. The performance of the commercial material was compared with the SEP prepared materials. It was found that, whereas the quasi-isotropic SEP specimens exhibited a much higher mass loss rate and a significant dimensional change upon exposure to the thermal environment than did the orthotropic ones, the commercial SEP-like materials did not exhibit these characteristics. There was no greater mass loss rate for the quasi-isotropic specimens, and no dimension changes were observed. The Nicalon reinforced materials in both configurations, as fabricated by SEP or by the commercial source, showed no mass changes and no dimensional changes.

Riccitiello, Salvatore R.↗