First off, please allow me to preface this by stating I am a HS graduate with a miniscule physics background, so if this is a stupid question, I humbly apologize. That being said... I have 2 questions, both of which are probably inane. #1. What would be the beneficial effect, if any, of linking several propellers in tandem, all mounted on a single shaft running the length of the tube? Would it provide more thrust? Would it even provide any thrust? #2. Would this arrangement provide any help with suppressing the prop noise? Is there such thing as a silent propeller? I'm working on a short story/novella, and I would like to be as accurate as possible. Thank you for humoring me.