7
$\begingroup$

I asked in chat about rocket engines not melting @ 3300°C despite steel melting at 1400°C. The two excellent answers were:

What I don't get is why isn't ceramic insulation used on the inside of nozzles and even the combustion chamber. Could be extremely thin(like the orange paint-like foam on the main tank of the STS' but for heat instead of cold) but will still reduce ablative wear on the heat-transmitting metal alloy.

I would appreciate answers to the literal question(floor tiles hehe) as much as answers as to alternative solutions and most of all - an explanation why none of that seems to transpire. What the question is not about are load bearing material selection, active heat management, feasibility of using just a piece of iron for simple missions(bombing people).

In addition to @Uwe's comment pointing out Inconel is used instead of steel, I just now landed on the following Wikipedia quote:

Often, heat-resistant carbon-based materials are used, such as amorphous graphite or reinforced carbon–carbon.

Improve this question
$\endgroup$
12
  • 6
    $\begingroup$ Ceramics tend to crack or break off in chunks. Some engines and motors do use ablative nozzles. space.stackexchange.com/q/22003/6944 $\endgroup$
    – Organic Marble
    Commented Jul 14 at 14:18
  • 4
    $\begingroup$ Rocket engines develop incredible pressure in the combustion chamber (which is kind of the point when you think about it), and thermal tiles are probably not rated for that kind of mechanical stress. For instance, the F-1 engine on the Saturn V had a chamber pressure over 70 atm. $\endgroup$
    – Cadence
    Commented Jul 14 at 18:39
  • 1
    $\begingroup$ Thermal design of rocket nozzles is a pretty broad discipline. Materials are selected with appropriate thermal properties, and then various other techniques are used to regulate the nozzle temperature to within its limits. I don't think ceramic tile is entirely ruled out--I'm almost positive aerospike designs have used ceramic tiles on the spike, but I can't find the example I'm looking for right now. $\endgroup$
    – Erin Anne
    Commented Jul 14 at 19:07
  • 1
    $\begingroup$ @Vorac See, I had initially assumed you were talking about non-ablative heat tiles like on the Shuttle or Starship, specifically because your combustion chamber ablating during normal flight makes it far more difficult to analyze. It's hard enough to model all the complexities of the chamber without it changing underfoot. $\endgroup$
    – Cadence
    Commented Jul 14 at 21:31
  • 1
    $\begingroup$ Vibration is also very problematic. $\endgroup$
    – user3528438
    Commented Jul 15 at 4:58

1 Answer 1

Reset to default
3
$\begingroup$

When considering a rocket engine design you want (among lots of other things) to maintain the highest pressure possible inside the combustion chamber, and the narrower nozzle throat, this will increase the speed of combustion products coming out of the nozzle.

The main issues I see with ceramic tiles are:

  1. Ceramic tiles are incredibly good at isolating heat but really weak mechanically so they would get immediately destroyed by the pressure and vibrations. (There was a saying that you could actually pierce a shuttle ceramic tile with a pen)

  2. You want the flow from the combustion chamber towards the nozzle to be as smooth as possible so it doesn't slow down. Tiles of any kind would break this smoothness, the fact that you would have edges, crevasses, even small ones, would be enough to cause considerable turbulence inside the engine, causing from the degradation of the performance up to the destruction of the engine.

Improve this answer
$\endgroup$
3
  • $\begingroup$ <things to keep in mind: weak engineering, weak physics knowledge> First point is excellent but second is moot as I asked "Could be extremely thin" as in "some kind of film" in contrast to "someone's bathroom". Will wait for under a week and then probably accept Your excellent thoughts as a final answer. $\endgroup$
    – Vorac
    Commented Jul 16 at 16:50
  • 4
    $\begingroup$ Being super thin means the ceramic layer won't do much. The physical thickness of the tile is a big part of how it does what it does. $\endgroup$
    – Darth Pseudonym
    Commented Jul 16 at 18:37
  • 1
    $\begingroup$ @Vorac What you're essentially asking is for Starlite to be brought back. Even then, I believe it was considered an ablative shield. $\endgroup$
    – David S
    Commented Jul 17 at 15:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.