Reentry vehicle nosetip after flying through rain at Mach 10, Sandia photo. One of the many engineering challenges to consider when designing hypersonic weapons.
Table of impact energies and speeds for water-density particles, courtesy B. Carmichael, Southern Research.
Hypersonic thought leaders emphasize there's much left to understand. At ISEC 2021, AFOSR high-speed aero lead Dr. Sarah Popkin noted that particulates were "highly suspected to impact boundary layer transition" (sudden turbulent flows on vehicle).
I'd add @DrChrisCombs has a couple tweets talking about boundary layer transition.
From the forthcoming report: just some of the many phenomena at play in these conditions. Adapted from Anderson's Hypersonic and High-Temperature Gas Dynamics (2019).
From a presentation at this 2021's TTC:
"turbulent boundary layers are a challenge, they can have 5 times or greater heating than a laminar boundary layer...But an equal challenge is dealing with the uncertainty associated with predicting that boundary layer transition..."
"...And because of that, sometimes it's easier to trip a boundary layer early and deal with that heating, even if it may increase the size of the thermal protection system, and just not having to figure out exactly where transition is going to occur."
This and more in our forthcoming report dropping Monday. Release will feature some of the biggest thinkers on this: Gillian Bussey (JHTO), Mark Lewis (NDIA), Kelley Sayler (CRS), Stan Stafira (MDA), & Tom Karako (CSIS), mod. by @TheDEWLine.
csis.org/events/complex…
Since some questions are coming in: the original photo doesn't say what material the nosetip is. From the looks I'd guess some variety of 3D carbon-carbon? Have a lot of past threads on the US' decadeslong RV nosetip efforts, see:
Some more C-C nosetip diagrams:
Also will note: @Casillic routinely finds and tweets interesting material from Sandia docs, including that photo. Some relevant tweets:
Also tossing this in the thread since it was asked:
For general interest, some more "environmental" factors warheads might encounter. Clockwise from left:
1) X-ray radiation damage on test RV (Sandia)
2) Natural charring of RV ablative heat shield after reentry (Sandia)
3) Simulated kill vehicle impact with test RV (LLNL)
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