Those compound engines were post-war variants and not the same as WW2 variants. They recovered some 450 lost hp per engine, and would noticably have improved power output as compared to the 1943 era B-29A R-3350 variants. F-13s weren't even re-designated as RB-29s until 1948. Early models of the R-3350 made only 2200 hp (early as in WW2 variants), while end-of-run (very post-war) models made 3500 hp.
For the B-29 we have the "loaded" weight was 120,000 lbs and MTO as 133,500 lbs from wiki. I do seem to recall early use in WW2 had something in the neighborhood of 100,000 lbs MTO allowed. This was most likely caused by the engines overheating in the hot tropical climate and the short runways available for the bombers -- meaning less weight allowed to just get them in the air safely. It was later increased by the time we were bombing Japan. Squadron Signal lists "Loaded Weight" as 135,000 lbs, though I think that by April 1945 this was pushed to 140,000 lbs. Let's go by this 140,000 lbs for our AH bomber.
This is going to look like crap, because it's in a table on the source but no tables in this forum (unless you manually do it all, which is a pain)... Edited as I copied/pasted.
Taken from: http://philcrowther.com/6thBG/6bgb29_perf.html
It mentions at the bottom the weight breakdown with full internal fuel ("standard total fuel") and 20,000lbs of bombs you're well past the 140K MTO limit, at 143K. More likely than not one bomb bay held aux fuel tanks and the other held as little as 5K ord.
I have yet to see any actual combat records or logs that state fuel load AND bombs. Many list bombloads, but don't say how much fuel, and those sources I can find that state fuel are hypothetical (like the link I posted above). It would be interesting to see fuel and bomb breakdowns in the same reference.
Krusty, as usual, I enjoy reading your posts in AH. First flight for me was in August 1954, and I did hear a lot of different "tales" concerning the old bird back in the WW2 days. One of the things we must remember, even though the 29 when though some testing after design, nothing like today's design testing, those brave young men, and sometimes old men, were actually doing flight testing as they flew into combat! One of the interesting problems they had when first putting the old bird into service was the amount of travel of the CG. As you know, as you burn fuel, your center of gravity moves to the rear in most aircraft.IN the 29, they discovered that burning the fuel from the outboards inward to the "center-inner" tanks next to the fuselage, the CG actually move forward and you became "nose" heavy, requiring a lot of nose up trim. As experience grew, they realized because of the slight taper of the wing, as they burned fuel, the CG moved towards the front. Then, because of safety concerns, growing out of wheels up landings and etc, it is best to get the fuel as far away from the fuselage as possible, so the standard way of burn for us was "center-inners" first, "center" next, then the outboard fuel cells last. This way, returning from a 12 or 14 hour mish, most of the fuel you have left is in the outer wing area, increasing the safety margin in the event of an accident. Our "flight" plan fuel load when something like this: 10 hours at 240 gallon per hour, plus 1 hour of reserve, 240 more gallons, plus 45 min, 180 more gallon for a total of 2660 gallon at takeoff. We allowed 60 gallon for start up, taxi and run up, plus the 15 gallons in each tank of unusable fuel, that is a total of 2710 gallon at start up. We only had only two 20MM tail guns, operated by a G-32 Radar aiming system, so we didn't have the weight that a standard B-29C had at takeoff. We had no fuselage tank, as it had been removed to install the ECM compartment.
