`Cruise missile graphite engine`

Cited as the existence proof that brittle-material jet engines can be built — when the engine only has to last an hour, the inspection problem becomes tractable. Graphite is tougher than most ceramics; coatings prevent burn-up.

So as long as you make a jet engine with no imperfections larger than half or one-tenth the size of a human hair, it'll run at great temperatures. We've already done that. It's called a cruise missile. The cruise missile engine is made out of graphite. Graphite's not particularly tough, but it only has to last for an hour, and the bigger problem is keeping it from burning up in an hour. They put coatings on it. But graphite's tougher than most of the ceramics.