Comments by "Stephen Villano" (@spvillano) on "Donut" channel.

@ColonelSandersLite one downside is high chromium stainless steels, which may end up pitted by the hypochlorite. I'm rather fond of phosphoric acid, which leaves a nice protective phosphide layer for exposed steel. It'd also be a nightmare if one did that to a camshaft... ;)
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One cheater's trick when approaching Mach 1 is to install a Mach probe, which goes supersonic first, with minimal drag. Of course, as your speeds increase, you also run into Mach heating of the leading surfaces, which can turn supersonic aircraft into literal ovens. The SR-71 used to pump the fuel through the leading edges and canopy edges to cool the aircraft down. The titanium also experienced significant work hardening from the heat and pressures involved. In short, for every can of worms that you open, you find another frigging can of worms inside and somehow, it's bigger. All, for the purpose of being able to set engines for Ludicrous Speed.
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