When the B-36 Peacemaker appeared in 1948, it was the largest and heaviest combat aircraft in the world powered by 6x 3500 hp R4360-53 prop engines + 4x J47-GE-19s @ 5200 lb st each for a speed of 430 mph at 40,000 ft. The bomber weighed close to 400,000 lbs loaded and had a wingspan of 230 ft, length of 162 ft. It had 2 bomb bays which could carry between 36-43 tons of conventional ordnance OR 2x Mk.17 H-Bombs (called SUPERS in the late '50s). Each H-Bomb weighed more than a complete DC-3 aircraft!!! The plane needed 17 crew in 2 comparments connected via a central tunnel with a powered trolley! But the only real flaw was that the combined powerplants led to slow speed, especially over the target. Plans were made to carry a fighter with it (FICON) but new jet designs were coming thanks to study of German jet technologies from WW2. Convair built a slightly larger transport variant that was the XC-99 and from this was a plan to make an all-jet version with more fuel capacity and load-bearing. It was also longer at 185 ft. The proposed B-99 would weigh 500,000 lbs and would carry up to 101,000 lbs of ordnance. It would get rid of the props and be powered by 12 jet engines in 6 pairs! This was beyond the average B-36 and would have been an equal of the B-52. Speed would jump from 430 to over 600 mph. While this all sounded great, the B-36 lost out to the B-52 Stratofortress as SAC's new guardian. The B-99 design therefore lost its window of opportunity. None were ever built as it remained a project aircraft. Had the B-99 been built it might have been called the "Tie-breaker". While not generally known, the B-99 aircraft is in Pat Frank's novel "Forbidden Area."