I almost skipped the videos embedded in this article, but they are well curated gems. A few tidbits I found amazing:

- 800°F (and above) was the temperature of their cooling air

- the engine ran too hot for electronics, so they designed a hydraulic mechanical computer responsible for regulating various inputs

- the roar from the two external 400 cubic inch Buick V8 engines originally used to start the aircraft was so irresistible to the hotrod enthusiasts running them that they sometimes neglected to disconnect in time before the starter engines overran RPM limits and "puked their guts out under the airplane" - they had to buy up so much replacement stock as to deplete every single junkyard across the USA of that particular model (so the story goes - probably hyperbole but a fun tale!)

In the 90s, NASA refurbished and extensively modified a mothballed supersonic Soviet-era Tu-144. The modifications included fitting different (Tupolev) engines. The total cost was $350M. It was used as a flying laboratory.