B-49. B-35 was the prop powered version, which was later converted into the YRB-49, with only four engines in the wings and two on external pods. Copy of YRB-49 Flight Manual attached. They built a number of those big flying wings but today NOT ONE survives, while we still have couple of B-36's, the XC-99, and an XB-70. Maybe there is something to those reports that it was all but invisible to radar and they did not want that fact getting out given that Northrop had been penetrated by Soviet agents. But if that was true, today we'd be building flying wing stealth bombers, wouldn't we?