Engineering topics

Williams, Joseph

Publications and source records attributed to Williams, Joseph.

6 records

NASA NTRS2019

Heatshield for Extreme Entry Environment Technology (HEEET) Thermal Protection System (TPS)

Starting in 2013 and completing in 2019, the Heatshield for Extreme Entry Environment Technology (HEEET) project has been working to mature a 3-D Woven Thermal Protection System (TPS) to Technical Readiness Level (TRL) 6 to support future NASA missions to destinations with extreme entry environments such as Venus, Saturn, Uranus, Neptune and high-speed sample return missions to Earth. A key aspect of the project has been the building and testing of a 1-meter base diameter Engineering Test Unit (ETU) representative of what could be used for a Saturn probe. This paper provides a high-level overview of the HEEET project including manufacturing and testing of the ETU for structural model verification, establish system capability and verify manufacturing workmanship.

Extreme Entry Environment↗

NASA NTRS2019

ADEPT Sounding Rocket One Flight Test Overview

On September 12th 2018, a sounding rocket flight test was conducted on a mechanically-deployed atmospheric entry system known as the Adaptable Deployable Entry and Placement Technology (ADEPT). The purpose of the Sounding Rocket One (SR-1) test was to gather critical flight data for evaluating the vehicle's in-space deployment performance and supersonic stability. This flight test was a major milestone in a technology development campaign for ADEPT: the application of ADEPT for small secondary payloads. The test was conducted above White Sands Missile Range (WSMR), New Mexico on a SpaceLoft XL rocket manufactured by UP Aerospace. This paper describes the system components, test execution, and test conclusions.

Cassell, Alan↗

NASA NTRS2018

Sizing and Margins Assessment of the Mars2020 Acusil-II Thermal Protection System

The Mars2020 entry vehicle is currently being developed by NASA to safely land its next rover on the Martian surface in 2021. The vehicle will be protected from entry aeroheating using three different TPS materials: PICA tiles on the forebody, SLA-561V on the backshell and Acusil-II on the parachute close-out cone (PCC) and its backshell interface plate (BIP). Mars2020's entry vehicle and TPS design is identical to the Mars Science Laboratory, NASA's last Mars lander; therefore, the purpose of this study is to assess the adequacy of the existing TPS design and thickness for Mars2020 predicted environments. This study focuses on sizing and margin assessment of Acusil-II TPS on the PCC and BIP. The methodology and analysis techniques that were used for assessing thermal margins are reviewed. Analysis assumptions and limitations are discussed in detail. Thermal sizing is performed at different locations and results are presented.

Acusil↗

NASA NTRS2018

Estimation of Heatshield Mass Loss for Mars 2020 Entry Vehicle

The Mars2020 entry vehicle is currently being developed by NASA to safely land its next rover on the Martian surface in 2021. During entry, the vehicle will be protected from aerothermal environments using a PICA (Phenolic Impregnated Carbon Ablator)-tiled heatshield. PICA loses mass through surface recession and in-depth pyrolysis as it is heated. Pre-flight knowledge of heatshield mass loss is required for vehicle balancing during critical mission events. This study attempts to predict the total mass loss experienced by the Mars2020's heatshield during its entry. A grid was created over the half of the heatshield which generated 108 points across a total of 9 spokes. Aero-thermal environments were provided from CFD (Computational Fluid Dynamics) calculations that considered a baselined trajectory. The TPS (Thermal Protection System) stack was a build-up of composite, aluminum, composite, an HT-424 bond, followed by PICA. The FIAT (Fully Implicit Ablation, Thermal-response) 1-D analysis utilized this TPS stack and the CFD environments and was run at each grid point giving mass flux information from the point of atmospheric entry until parachute deployment. The mass flux due to recession and pyrolysis gas was summed and integrated first through time and then across the half heatshield using a polar integration tool. The mass loss results were mirrored to the other half of the heatshield to calculate total mass loss throughout the entry phase of flight. This total mass loss value and its distribution was used by entry vehicle designers to account for CG (Center of Gravity) offset during parachute descent when the heatshield is no longer losing significant mass.

PICA↗

NASA NTRS2018

Overview of Heatshield for Extreme Entry Environment Technology (HEEET) Project

The objective of the Heatshield for Extreme Entry Environment Technology (HEEET) projects is to mature a 3-D Woven Thermal Protection System (TPS) to Technical Readiness Level (TRL) 6 to support future NASA missions to destinations such as Venus and Saturn. Destinations that have extreme entry environments with heat fluxes up to 5000 watts per square centimeter and pressures up to 5 atmospheres, entry environments that NASA has not flown since Pioneer-Venus and Galileo. The scope of the project is broad and can be split into roughly four areas, Manufacturing/Integration, Structural Testing and Analysis, Thermal Testing and Analysis and Documentation. Manufactruing/Integration covers from raw materials, piece part fabrication to final integration on a 1-meter base diameter 45-degree sphere cone Engineering Test Unit (ETU). A key aspect of the project was to transfer as much of the manufacturing technology to industry in preparation to support future mission infusion. The forming, infusion and machining approaches were transferred to Fiber Materials Inc. and FMI then fabricated the piece parts from which the ETU was manufactured. The base 3D-woven material consists of a dual layer weave with a high density outer layer to manage recession in the system and a lower density, lower thermal conductivity inner layer to manage the heat load. At the start of the project it was understood that due to weaving limitations the heat shield was going to be manufactured from a series of tiles. And it was recognized that the development of a seam solution that met the structural and thermal requirements of the system was going to be the most challenging aspect of the project. It was also recognized that the seam design would drive the final integration approach and therefore the integration of the ETU was kept in-house within NASA. A final seam concept has been successfully developed and implemented on the ETU and will be discussed. The structural testing and analysis covers from characterization of the different layers of the infused material as functions of weave direction and temperature, to sub-component level testing such as 4-pt bend testing at sub-ambient and elevated temperature. ETU test results are used to validate the structural models developed using the element and sub-component level tests. Given the seam has to perform both structurally and aerothermally during entry a novel 4-pt bend test fixture was developed allowing articles to be tested while the front surface is heated with a laser. These tests are intended to establish the system's structural capability during entry. A broad range of aerothermal tests (arcjet tests) are being performed to develop material response models for predicting the required TPS thickness to meet a mission's needs and to evaluate failure modes. These tests establish the capability of the system and assure robustness of the system during entry. The final aspect of the project is to develop a comprehensive Design and Data Book such that a future mission will have the information necessary to adopt the technology. This presentation will provide an overview and status of the project and describe the status of the tehnology maturation level for the inner and outer planet as well as earth entry sample return missions.

Ellerby, Don↗

NASA NTRS2018

ADEPT SR-1 Development and Testing

The Adaptable Deployable Entry and Placement Technology (ADEPT) Sounding Rocket One (SR-1) fight test will be the first sub-orbital flight of Nano-ADEPT. Nano-ADEPT is a deployable heatshield for secondary payload missions desiring to re-enter the Earth's atmosphere or deliver small science payloads to Mars or Venus. Two units have been built and tested in preparation of launch: one designated the "Spare" unit and one the "Flight" unit. The general development approach has been to perform all procedures on the Spare prior to performing them on Flight. This approach has served the project well, allowing for procedures to be rapidly developed and tested on spare hardware where mistakes are less consequential. Conversely, when schedule constraints have come up, the approach has allowed the project to rapidly pivot to an approach where Flight drives the critical path rather than Spare. This approach has enabled relatively rapid development of Flight where technical risk is balanced with schedule realism. This presentation will describe the various tests that have been performed on Nano-ADEPT Spare and Flight units to prepare for the sub-orbital flight. The purpose is to communicate the development approach we took for this low-cost, moderate-risk flight test and hopefully engage the EDL community in a wider discussion of risk-balanced approaches toward flight hardware development of secondary payload atmospheric entry systems.

Smith, Brandon↗