[reed13k]

at that speed the friction generated temperature would be about 15000K

Hypersonic vehicles like reentry capsules or experimental aircraft (e.g. NASA’s X-43) experience surface temps of 1,500–3,000 K.

A commercial aircraft (if it existed at this speed) would likely use ablative shielding or regenerative cooling to keep skin temps in the 1,000–2,500 K range.

Those temps are still above Aluminium melting temp of ~933K

[reed13k]

That temp for friction was assuming standard international flight altitudes

[TexasGator]

“at that speed the friction generated temperature would be about 15000K”

Not at 18 miles high.