[foldr]

You did challenge the claim that they could complete take off on a single engine: https://news.ycombinator.com/item?id=44256705

[defrost]

Not at all.

Landing sans power is landing with no thrust (no functioning engine).

Completing a take off with no thrust isn't possible unless the craft is a glider, a hot balloon, or a ballistic launch .. taking off with a single engine is not "taking off sans power".