
Is it due to space, weight, or both? I've read that the internal bays' shape & size on version B were to be kept the same as on A & C, and that a set of SDBs can fit in there, either of which which would mean the limit excluding 2000-pound JDAMs has to be weight, since those (or at least the smaller type) would fit in such a space. But I've also read that a set of SDBs has to be missing one bomb in order to be put inside, which indicates that the issue must be space, and contradicts the "same as A & C" thing.
What makes me wonder is that, although the difference is always described in terms of what types of JDAM it can carry, it has implications for other kinds of weapons as well, which don't get mentioned. A space restriction limiting SDBs to three instead of four could also rule out JSM and/or JSOW, which are significantly longer than any JDAM or two SDBs, with fins sticking out in the back (and probably wings still protruding even when folded, on JSM, which is shorter but has bigger tail fins)... and while a weight restriction somewhere between the weights of "1000-pound" and "2000-pound" JDAMs certainly lets JSM in, since it's lighter than the former, it might exclude JSOW, which is slightly heavier.
My best guess (because it's what creates the fewest contradictions between different things I've read) is that the restriction for F-35B is a combination of a weight issue (which affects the heavier JDAMs) and a space issue (which affects the fourth SDB). But that could mean that either JSM or JSOW could be ruled out, for more than one possible reason apiece... or they might both be fine... yet I haven't seen anybody saying whether they are or not.
But then, exactly what is the weight limit? And exactly how much did the space get snipped, and where, and what does B have there instead that A and C don't? (Are there numbers for this or illustrations of it?) Since the idea of leaving the bays the same was ever even considered, it can't be the lift system that's intruding, so my guess is just fuel tanks to alleviate version B's loss of fuel capacity elsewhere...
What makes me wonder is that, although the difference is always described in terms of what types of JDAM it can carry, it has implications for other kinds of weapons as well, which don't get mentioned. A space restriction limiting SDBs to three instead of four could also rule out JSM and/or JSOW, which are significantly longer than any JDAM or two SDBs, with fins sticking out in the back (and probably wings still protruding even when folded, on JSM, which is shorter but has bigger tail fins)... and while a weight restriction somewhere between the weights of "1000-pound" and "2000-pound" JDAMs certainly lets JSM in, since it's lighter than the former, it might exclude JSOW, which is slightly heavier.
My best guess (because it's what creates the fewest contradictions between different things I've read) is that the restriction for F-35B is a combination of a weight issue (which affects the heavier JDAMs) and a space issue (which affects the fourth SDB). But that could mean that either JSM or JSOW could be ruled out, for more than one possible reason apiece... or they might both be fine... yet I haven't seen anybody saying whether they are or not.
But then, exactly what is the weight limit? And exactly how much did the space get snipped, and where, and what does B have there instead that A and C don't? (Are there numbers for this or illustrations of it?) Since the idea of leaving the bays the same was ever even considered, it can't be the lift system that's intruding, so my guess is just fuel tanks to alleviate version B's loss of fuel capacity elsewhere...