Understanding the ProblemIn the B-17 there were four bomb racks, with two facing out from a center support and two facing in from the plane’s outside walls, as can be seen in this photo.
Note that these were not “chutes” with bombs stacked on top of each other. Each bomb was firmly attached by a shackle system, that included a hard inverted U welded to the bomb, a bracket with clips to lock into the bomb’s U, and the anchor brace that attached the bracket to the bomb rack itself. Bombs were then braced with tensioning screws that kept them from shifting.
Bombs were released mechanically or electrically when the shackle bracket was allowed to pop free of the bomb rack. They could be salvoed with defined delay, or dropped singly – just as is modeled by AH2.
Bombs were not guided out of the aircraft – they went into “free fall” from the time they were released.Consequently, it should be obvious from the photos that bays were designed with essentially level drop angles in mind. If the bomber was angled too sharply, the bomb would strike the bulkhead as it left the aircraft. This would likely cause structural damage, proportional to the weight of the bomb and the forward vector of movement. (I.e., the steeper the angle, the more of the weight would be directed into the structure.) Bombs from upper racks would strike bulkheads when flying at less severe angles, since they had farther to fall before leaving the plane. To give an idea of the clearance needed, the photos above show 250lb bombs shackled in place. Also, larger and heavier bombs required more clearance – and could do more damage if dropped inappropriately.
How much damage could be done? Remember that these aircraft were largely made of aluminum, and not armor plate. For example, look what A SINGLE 20mm shell did to a B-24 over Balikpapan.
Just imagine what 1000lbs of free falling iron could do!
The concept of drop angle limitation applies to every bomber with a bomb bay, though I have not been able to yet track down the equivalent data tables for other bombers. None the less, here’s an illustration from the cavernous bay of the Lancaster.
The anterior bombs would clearly do damage if dropped steeply.
But enough of the qualitative description. Here is the actual Bomb Release Angles Chart from the 1948 version of the B-17 Flight Operations Instructions AN 01-20EG-1. (I also have the 1944 version, but though it has the same data its presented less clearly and over 2 pages.) I left the file big for readability – my apologies to those with slower connections.
Does the potential damage matter? Obviously in real life the pilots wanted to keep their planes 100% intact, but that restriction does not apply to Aces High. All the same, at LancStuka angles a 2000lb bomb could realistically end up plowing into the pilot’s back rather than dropping magically from its current point source, and we shouldn’t tolerate that either.
