[AR] Re: reentry Isp (was Re: SSTO)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Tue, 13 Feb 2018 16:13:19 -0500 (EST)
On Tue, 13 Feb 2018, rebel without a job wrote:
The conclusion I'm drawing is that only a tiny bit of the re-entry
energy is carried off by the ablated particles of the heat shield, and
the vast majority of the re-entry energy is used in heating the
surrounding air...
Am I getting this right?
Skipping numerical details, you are. Actually soaking up *all* the energy
would vaporize the whole spacecraft, even if it was solid graphite.
Almost all of it goes into shock wave and hot air, and very little reaches
the spacecraft. Keeping as much of it as possible *out* of the spacecraft
is key to reentry design; in particular, this is why reentry vehicles want
to be blunt, to keep the shock wave off the surface. (The shuttle orbiter
is not an exception -- to a first approximation, it reentered belly-first,
not nose-first.)
Henry
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