A large 12 x 12 x 2″ test block used for the heat shield of the Apollo Command Module in 1966.

AVCOAT was produced by AVCO corporation and integrated into the Command Module’s Thermal Protection System by North American Aviation. These heat shields were designed to withstand temperatures in excess of 3200°C. Discovered by accident, AVCOAT is made of low-density silica fibers in an epoxy-novalac resin, filling a fiberglass-phenolic honeycomb.

Each of the 370,000 cells is filled with resin by hand!

AVCOAT was recently chosen by NASA for the Orion spacecraft in the Constellation program.

14 responses to “Apollo AVCOAT Honeycomb Heat Shield”

  1. And an analysis from the Spaceaholic:

    jurvetson_avcoat_5026_test

    "based on my understanding how AVCOAT was developed and its application on the CM, I think your heat shield block is particularly significant given the presence of the test artifacts."

  2. The trial cell repairs are representative of the process applied after initial gunning of the slurry into the nylon cells (all 370K cells comprising the Apollo Command Module thermal protection system (TPS) were gunned by hand); after curing NDE was utilized to confirm integrity. If there were any bubbles the cells were subsequently drilled out and refilled.

    The Ablator plug tests demonstrated the method used for sealing (via threaded AVCOAT plugs) fasteners used for attaching the heatshield to the Apollo Command Module. There were also larger plugs which provided access to dump ports (these ports were used to evacuate propellants from the CM RCS system after fueling – an action that was required in conjunction with post-flight vehicle safeing and in the event of a launch delay/pre-flight testing).

  3. light will, …event u all lee ego 🙂 why as k why? lol/…one ness e go lee lmao…:) >>:::)))!

  4. I can’t but think of propolis…

  5. I would hope that there have been significant improvements in the material since 1966?

  6. Why mess with success? The AVCOAT formulation selected for its latest application is essentially the same as that used in the 60’s with some minor tweeks associated with its manufacture (the adjustment does not enhance performance) . Interestingly AVCOAT was evaluated against another type of heat-shield material (Phenolic Impregnated Carbon Ablator – PICA) and while NASA chose the former for the Orion CEV, Space-X opted to go with a PICA derivative for its Dragon capsule.

  7. I can only imagine the thousand of hours (and various test batches) of stuff that led up to this final product.
    !

  8. Interesting, so it was designed well…classic…(kinda like Coco Chanel design) and also looks appealing…..and tasty…

  9. [http://www.flickr.com/photos/solerena]
    Maybe more like Pemmican…
    A true classic that is still the best arctic food supply pound for pound…
    !

  10. it’s a fine artifact!

  11. Yummy insulation for the honeycomb hideout….

    I met recently with the tech lead for the Orion heat shield (he came by to visit this artifact).

    A test block was generated each day in the same workflow as was used for the capsule. The workers would build several flight panels and one spare each day (this one was for Sept 12, 1966). So if testing is needed, they can work on the spares and leave the flight articles untouched (unless they discover a problem). The hope is that materials variation and operator errors would be replicated across all of the panels built in a given day.

    It was quite a manual process, with each of 370,000 columns filled successively by hand with a specialized caulking gun (the amount deposited in each cell is electrically controlled and measured to minimize variation).

    And they also try to replicate the repair steps on the blank panel, where the bubbled columns are drilled out and refilled before the 350° cure. So these panels would have repair areas if any of the flight panels took them.

  12. And I have a 1966 pamphlet for North American Aviation employees (Skyline, Vol. 24, No.1). "Since 1955 Avco has been sky-high in the solution of re-entry heating problems, notably in developing the re-entry vehicles for the Atlas, Titan and Minuteman ICBMs."

    IMG_4405
    "The material spills out of the cell holes so that the entire cover, at this point, has a shaggy appearance. The entire moduloe is ‘shaved’ with a complex machining operation in order to obtain all the subtle variations in thickness which range from three inches on the blunt toe that takes the greatest heat, to less than an inch on a portion of the side. In its final form after curing, after x-raying which detects voids, and after final machining, the ablator is smooth and polished."

    IMG_4403

  13. [http://www.flickr.com/photos/jurvetson]

    Anthony Stephen Daddario aka "Tony Daddario" was the head of the group that worked on the honeycomb heat shield and he did the "original analysis" while employed at AVCO. He was an aerospace engineer and inventor. He was a genius when it came to the stresses of metal.

  14. Amazing collection, and great photos.

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