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crew dragon on launchpad

(Source: Nasa Spaceflight article)

While looking at the new images of the upcoming crew dragon launch I noticed a distinct lack of holes in the part of the dragon the Engines are supposed to be in. So I started researching: During assembly there are a visible covers both in the top of the bay, where the engines should be and also below that in the back of said bay:

dragon during assembly

(Source: SpaceX flickr)

These covers, or similar ones seem to already be in place during transport:

dragon during transport

(Source: SpaceX Instagram via geekwire, because Instagram does not want to permalink images)

During the Pad Abort test however there is no covering to be seen:

Abort Vehicle on Pad

(Source: SpaceX flickr)

So my questions are

  • Why are these covers there?
  • Why were they not there during the pad abort?
  • What does the one in back mean?
  • How do they get jettisoned reliably?

I could not find answers to these questions myself, because these covers do not seem to be acknowledged anywhere.

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    $\begingroup$ in the assembly picture, one can make out the text "remove before flight" on the "ribbons" hanging from the covers. These covers are manually removed close to launch. They were not present in the launch abort test picture as they had already been moved. $\endgroup$
    – user20636
    Commented Jan 26, 2019 at 20:09
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    $\begingroup$ Might be similar to the items used on the Shuttle. space.stackexchange.com/questions/33828/… $\endgroup$
    – Hobbes
    Commented Jan 26, 2019 at 23:01
  • $\begingroup$ Nice work! Keep it up. $\endgroup$
    – Muze
    Commented Apr 9, 2019 at 19:13

1 Answer 1

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The abort test was done several years ago. Quite a few changes have been made since. The covers on the Super Draco nozzles are quite recent, from what I've seen. The entire pod area now has a silver-colored surface, the same coating used at the edge of the heat shield where it joins the capsule. The silver-colored surface was used previously on Cargo Dragon, on the edge of the heat shield. (Just on the edge; the heat shield aerodynamics place the edge outside of the worst of the heat.) The best answer I could find indicated an aluminum-based paint for heat protection The covers are not removed before launch, as seen in this NASA video, in the first seconds, and at 3:17 when undocking.

See also this vid at 8:30 mark

on the recovery ship. The nozzle covers are still in place. This makes sense if their purpose is to protect the Super Dracos from salt water exposure. Tim Dodd, the Everyday Astronaut, also pointed out that open nozzles would act as air scoops during descent, which would be problematic re aerodynamics. The silver paint appears to have burned away, leaving only smudges But due to the bright sunlight and overexposure setting of the camera, the silver just possibly is showing as white. The Super Dracos are apparently intended to fire thru the covers, or blast it off, during an abort. A hypergolic ignition/explosion is reliable, and more than strong enough to blast off even a firmly affixed cover.

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    $\begingroup$ "more than strong enough to blast off even a firmly affixed cover." It would be foolish indeed to design it so that the cover wouldn't come off. $\endgroup$
    – Organic Marble
    Commented Mar 10, 2019 at 18:40
  • $\begingroup$ Well, yes, but I was addressing the "reliably" part of the questioner's "How do they get jettisoned reliably?" phrase of the post. $\endgroup$
    – SpaceInMyHead
    Commented Mar 11, 2019 at 2:58

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