B29 >> Initial Climb: 900 fpm @ 150 mph Indicated (@99,480 lbs).
B17 >> Initial Climb: 900 fpm @ 135 mph Indicated (@57,000 lbs).
Lancaster >> Initial Climb: 1000 fpm @ 145 mph Indicated (@52,000 lbs)
What I was trying to point out, is that the B29 had a VERY shallow initial ascent angle. More shallow than either that B17 or the Lancaster. With that comes more difficulty in taking off, and hence we will have to find the proper runway more often. Turning a 100,000lb+ plane isn't going to be very 'easy' in a simulated environment and the loss of speed while turning is going to be almost twice (if not more) what the loss is in B17's. B29's could go up to 135,000lbs, B1-G7's around 65,500lbs turning that thing isn't going to be even slightly close. If you do try and turn in the climb you're going to lose your airspeed and tank it.
As others have pointed out, IF you were lucky to not lose an engine on ascent (most frequently to overheating) the plane grabbed well as it got higher and higher. If you did lose one you literally couldn't continue to climb and ended up in the water. This was a common and well documented issue with the B29's more so in their early day's.