Thanks, Doug. That was a really fun video to watch.
The frightening thing about machining titanium is that the hot powder and shavings can fuel a Class D fire, as is the case with many exotic metals (magnesium!), but something that makes titanium especially dangerous is a titanium Class D fire can burn hot enough to liberate the atomic oxygen from the carbon in CO
2.
The native
engines in the 1950s era
Avro Arrow used a lot of titanium. Titanium fires and the problem with trying to extinguish them with CO
2 was an unexpected surprise during development. Fun fact about titanium and that particular engine-airplane combination, one of the factors that limited top speed was the materials limit of the temperature of the last stage of the titanium
compressor. On paper the engine had an unremarkable pressure ratio (remember, compressing air heats it) but combined with the ram temperature rise of a Mach 2+ dash speed, the engineers expected that the titanium compressor blades would be pushing the strength-temperature limit of titanium in the last stage of the compressor. You usually think of fast jets being limited by available thrust and powerful jet engines as being limited by the turbine temperature...
