I'm looking for the exact passage, but it might also be in "Aerial Armament in World War II" also by Wolf.
Somewhere he stated that the main problems the RAF overcame were in 2 main area's.
First, turret extension retraction, the USAAF procedure was for each B-25 to extend and retract the turret as needed. Because of the slow movement and the drag penalty it made keeping formation very difficult (as well as missing attacks due to slow speed). The RAF solution to this was very simple, after takeoff extend the turret and leave it down, for the whole flight (and just accept the slower formation speed). LOL
Second, another major USAAF issue with the turret was maintenance of the optic system. Given the grass/mud fields the USAAF was using during the Mitchells early deployment, it created an extra problem after taking-off from a wet field and messing up the periscope glass. This couldn't be cleaned in flight so imagine the frustration of extending the turret and getting into position only to not see anything. The RAF (for the most part) didn't have this problem as the B-25's were usually operated off of paved runways.
I'm not sure if they addressed the nausia, but them Brits are tough, maybe the stiff upper lip helped keep breakfast down!
