wrote:

Not that it applies to the B-17, but I would think that unless hydraulic
flaps were preloaded (spring or other or were heavy) to extend without
hydraulic pressure, the airflow would keep them retracted until airspeed
decreased or even until the a/c got on the ground. As for the gear,
unless it was kept in the retracted position by hydraulic pressure
alone, as on many modern light aircraft, the mechanical uplocks would
keep the gear up. Also, depending on gear door operation, the airflow
could very well keep the doors closed, or at least partially closed,
until airspeed decreased. Lack of pressure could also just allow the
doors to stay closed & the gear stay up regardless, depending upon how
they're actuated.

Quite right, I forgot to mention that...
--

-Gord.