The Navy's 1920 Indiana experiment was already investigating aircraft attack before Project B. The old pre-dreadnought provided a target for studying bomb damage. Sand-filled bombs helped test accuracy, while explosives placed on the ship simulated destructive effects. Captain William D. Leahy's report judged contemporary aerial bombs unlikely to destroy or completely disable a modern battleship. Mitchell's campaign and congressional pressure then pushed the Navy toward a more public joint demonstration.
Chapter · 1:34:25-1:40:08
The Navy's Indiana test and William Leahy's report
Before Project B, the Navy had already attacked Indiana from the air and used controlled charges and practice bombs to study accuracy and damage.