Flying Fortress Designation Numbers?

[Jennison]

Hi: Basic question if I may ask: can someone tell me what the number means that comes after B-17 and the model type (F, G) and before the factory designation? For instance. take "B-17F-30-BO". What does the "30" signify?

Thanks very much, Jennison.

 

[Wurger]

The number after the marking of the aircraft version was the block number and then the manufacturer's code. In the case the B-17F was of the 30th production block and made by the BO factory ( Boeing Airplane Co. Seattle, Washington). The block number refers to a production run. All aircraft built during that production run are all built exactly the same.

Some info you may find here ... U. S. Army Aircraft Designations 1939-45