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During launch and landing, dust, dirt and debris may be stirred up. For non-gimbaling engines like the vac Raptors on Starship, can't the engine fairing/boattail be closed? I imagine titanium sheet for the purpose. Understandably, dissipation of heat from the engine is another important consideration but will the physical protection outweighs the thermal protection?

Raptors engine parts seemed pretty exposed from the bottom view.

Raptors seemed pretty exposed.

So was S-IC.

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But Saturn S-I wasn't.

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Neither is the CBC.

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Why?

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    $\begingroup$ What do you mean by "hood of rocket"? Are you taking about the nozzle? If you seal the rocket engine nozzle, then how would the exhaust go out? $\endgroup$ – Star Man Nov 18 '20 at 3:58
  • $\begingroup$ @Star Man: I don't mean closing the exhaust but covering the under side. $\endgroup$ – seccpur Nov 18 '20 at 4:38
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    $\begingroup$ "enormous dust, dirt and speeding debris are stirred up" - do you have any examples? With the vast quantities of rocket exhaust heading away from the engines at great speed, how would such debris make its way towards the back of the engines? $\endgroup$ – user20636 Nov 18 '20 at 9:23
  • $\begingroup$ @JCRM: During second static fire test on Starship SN8 recently, it is assumed that the damage on one of the raptor engines may be due to such debris. Dust will be worst during landing. $\endgroup$ – seccpur Nov 18 '20 at 9:40
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    $\begingroup$ @seccpur many people read the news and from your title recognize exactly what you are describing, but many don't. It's always better to cite some relevant news within your question, even if it's simply a link to the Pod Bay referencing an Elon Musk tweet. $\endgroup$ – uhoh Nov 18 '20 at 10:50
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The "powerheads" of the shuttle's main engines were nicely sealed away to provide thermal and debris protection.

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Photo credit NASA - from STS-127

These diagrams from the KSC SSME System Engineering Handbook show details of the closures. You can see the sliding engine-mounted shield that allowed the engine to gimbal in the first diagram.

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    $\begingroup$ Excellent answer supported by visual proof. Is current starship prototype engine much expose compared to the shuttle? $\endgroup$ – seccpur Nov 18 '20 at 16:02
  • $\begingroup$ @seccpur I know very little about spacex. Some boosters have their engines just hanging out in the air like this Titan airandspace.si.edu/sites/default/files/styles/slideshow_lg/… But I suspect it launched off an elevated structure of some sort, not a concrete pad. $\endgroup$ – Organic Marble Nov 18 '20 at 17:33
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    $\begingroup$ But it can't land on concrete on moon and even on launch pad without kicking some dust. $\endgroup$ – seccpur Nov 18 '20 at 17:49

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