Heatshield Block Ablator Architecture

Heatshield Block Ablator

Challenge

 Large Faceted Aeroshell Structure (5.0m)
Large Faceted Aeroshell Structure (5.0m)
The concept of a block-ablator (B-A) heatshield was originated at NASA's Ames Research Center in 2006-07. During that time, the ARC TPS staff was doing characterization testing and developing heatshield designs made from low-density PICA ablator for the Crew Exploration Vehicle (Orion) and other NASA systems. PICA is a "ceramic" that is produced and applied monolithically for a small EDL vehicle or in large tiles, or "modules," for a larger vehicle. While PICA is reinforced internally with carbon fibers, PICA heatshield designs at that time did not have a secondary reinforcement system such as composite honeycomb (H/C). The concept of a B-A heatshield was to produce and bond precision H/C to structure and then insert and bond high-tolerance thermal protection blocks into the cells of that H/C. The idea was generated as a means of:
1) reinforcing and strengthening lightweight and perhaps somewhat brittle ablator and ceramic TPS materials; and 2) anchoring the heatshield via H/C bonding and enabling an initial pull-test of bonded, unfilled H/C to validate bond strength. The block-ablator concept was inclusive of a wide range of ablator materials, not just PICA and other lightweight systems. Molded, polymer based ablators in a cured form – such as mid-density phenolic-carbon ablators – might also be milled into precision blocks and bonded into block-ablator H/C. The B-A heatshield requires a faceted aeroshell structure. Shown in the figure above, this is a structure with flat faces to which flat H/C can be bonded. However, B-A can accommodate simple curvature at the cone edge as shown.

Solution

The Ablatives Laboratory (ABL) was tasked to contribute to the B-A effort in the following primary ways: 1) develop a producible design for a block-ablator heatshield system including honeycomb and block configuration and their basic dimensions; 2) select materials and develop a reliable method for producing block-ablator H/C; 3) develop processes and steps for milling blocks from slabs of ablator material; 4) select adhesives and investigate bonding processes for bonding H/C and TPS blocks; 5) produce eight large flexure test samples (i.e., 16.0-in long block-ablator on 30.0-in. long aluminum plates) made from PICA and phenolic ablators for bend testing at NASA/LaRC; 6) produce manufacturing demonstration units (one flat and one curved) of the B-A system using NASA-supplied substrates and PICA ablator billets; and 7) build PICA and phenolic thermal test samples and conduct arc-jet testing (stagnation and aeroshear series) to evaluate block-ablator system performance.

ABL 24-in. Square Honeycomb Panels
ABL 24-in. Square Honeycomb Panels
ABL CNC-Milled Phenolic Ablator Blocks (384)
ABL CNC-Milled Phenolic Ablator Blocks (384)
ABL 3-Axis CNC Milling of PICA Ablator Blocks
ABL 3-Axis CNC Milling of PICA Ablator Blocks
Finished PICA Ablator Blocks Ready for Bonding
Finished PICA Ablator Blocks Ready for Bonding
Bonding Trapezoidal Ablator Blocks to Honeycomb (PICA and Phenolic)
Bonding Trapezoidal Ablator Blocks to Honeycomb (PICA and Phenolic)
Bonding Trapezoidal Ablator Blocks to Honeycomb (PICA and Phenolic)
Bonding Trapezoidal Ablator Blocks to Honeycomb (PICA and Phenolic)
Block-Ablator Flexure Test Samples – PICA / LI-900
Block-Ablator Flexure Test Samples – PICA / LI-900
Block-Ablator Aeroshell Curved Cone-Edge Sample
Block-Ablator Aeroshell Curved Cone-Edge Sample

Thermal Protection Technology and Engineering

Thermal Protection Technology, Engineering, and Manufacturing

ARA’s Ablatives Laboratory is a NASA-dedicated facility focused on technology advancements for thermal protection systems (TPS) such as planetary... more

Ablatives Lab

Ablatives Laboratory

Research, development and manufacturing of ablative heatshields and thermal protection systems for entry and launch vehicles, and missile systems... more