Don't worry about it. I never did pass any of them fortunatly BDU was hard up and gave me a U-Boat command. They did however make me take Bernard along. After two patrols with him I stuck him into the aft tube.
You will find that it does not matter if you can shoot a plane down because smart commanders always crash dive. You wont win against a plane.... In regard to torpedos it gets easier each patrol as you learn. Start with assisted targeting. Your WO needs something to do so he won't be climbing your back while your at the periscope.
Good hunting.
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