One problem with the article on the YB49, linked from the one on the B2. I saw one of those in flight out of Andrews AFB when I was a kid in the early 60s. I was born after the last plane was allegedly destroyed in a fire. The exhaust trails were a lot like an F-4, so I doubt it was the prop version. Nothing else looked like that plane except the YB35s which were supposed to have been destroyed, unless it was the YB49A variant, about which the article gave no details at all.