Steel for Shuttle

In article ,
says...

On 2019-11-14 19:54, Alain Fournier wrote:

Steel has much lower conductivity than aluminium. So this isn't as much
a problem as it would be if aluminium was used.

As I recall, no aluminium was bare on the shuttle, was all protected by
tiles/blankets. And the tiles were thick and heavy to ensure the
aluminium remain nice and comfy cool.

This is not at all true. The space shuttle's aluminum skin actually got
*hotter* after landing due to "heat soak". The heat that was still
inside the thermal protection had to go *somewhere*. Roughly half of it
radiated outward and the other half went into the aluminum skin.

https://www.nasa.gov/centers/johnson...s-ch4b-pgs182-
199.pdf

From above:

Thermal Protection System materials
protected the Orbiter?s outer skin from
exceeding temperatures of 176°C
(350°F).

So, the skin got pretty warm if the limit was 350 degrees F (literally
the default temperature of both of my ovens in the kitchen). I would
not call that "comfy cool" at all.

Starship will have portions of its skin as Shiny exposed steel and the
tiled portions will will still allow the steel under the tiles to heat
up to high temperatures (since it can support such, allowing for
thinner/lighter tiles).

Yes, but it won't conduct heat to the inside as well as aluminum would
because steel has lower thermal conductivity compared to aluminum.
That's why the bases of my stainless steel cookware all have copper
inside the base. Copper has a very high thermal conductivity, so it's
put there to more quickly move the heat from the stove to the food being
cooked (copper is also more expensive than stainless steel, so these
sorts of pans aren't cheap, but they'll last a lifetime if taken care
of).

6 Best Stainless Steel Cookware with Copper Core (Induction Ready)
https://www.magneticcooky.com/stainl...e-copper-core-
induction-ready/

If some of that shiny steel reaches 1000°C, there is both conductive and
radiative heating of components inside the skin.

Yes, but I would think that there would be a healthy safety margin since
300 series stainless steel loses its strength at about 1000 degrees F.
Also, you can put interior insulation around sensitive components. You
don't have to turn the entire interior into an oven.

We know of mechanisms to control the "winglets" and landing gear which
would have to be fairly close to the skin. Not sure what sort of sensors
it will need to deploy for re-entry. For Earth, they can use good GPS
antennas to and innertial sensors well inside the ship to control
re-entry, but on Mars, wouldn't they need to deploy air probes, and air
pressure sensors and possibly radar to execute landing? Those would be
stowed inder the steel skin for re-entry and doors open to deploy them
once at safe altitude, but that still needs those sensors be near that
steel skin.

Sure. All of such "sensitive" equipment would likely have additional
insulation and possibly even active cooling.

This type of stuff is the bread and butter of structural and materials
engineers in aerospace engineering. Designing such things is literally
their day job.

Jeff
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