Solotk
The second of your B17 photos shows the aircraft doing what we of the UK C130 fleet used to call the 'snatch' - a mail pick-up using a hook on an aircraft-mounted winch to snare a suspended wire or rope attached to the mail package, which can be seen on the ground. The technique was revived by the C130 fleet at the end of the Falklands war to facilitate the delivery of important mail back to UK while the Stanley runway was out of commission. I have a number of photos of the technique being practised on Salisbury plain in the summer of '82 - I'll see if any of them are worth posting here!