[PSUBS-MAILIST] props

[hank pronk via Personal_Submersibles]

Alan,
Maybe it is better to make a prop that works in both directions.  I can afford to loose efficiency, that is better than mounting two thrusters in my case.
Hank--------------------------------------------
On Sun, 12/14/14, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] props
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Sunday, December 14, 2014, 7:04 PM
 
 Hi
 Hank,I guess
 you would be getting the same thrust in both directions,
 butyou would
 be doubling the pitch of the propeller by doubling up, &
 there maybe a lot
 of turbulance between the propellers.There are
 propeller calculators that take a number of input variables
 like hp, revs, boat size,intended
 speed, diameter of the propeller & pitch. You leave one
 input out & it calculatesthat for
 you. You could call the two propellers one (add the two
 pitches together) & see what diameter
 it calculates for you at a given pitch & play around
 till you get the most efficientdiameter /
 pitch combination; then use the diameter but halve the
 pitch.I
 don't think I made a lot of sense, but if you go down
 that path I will explain a bit better.However
 given that submarines operate better with bigger diameter,
 lower pitch propellersit
 probably isn't a good idea going to two smaller higher
 pitched propellers.Alan
     
    From: hank pronk via
 Personal_Submersibles
 <personal_submersibles at psubs.org>
 
 To:
 personal_submersibles at psubs.org 
  Sent: Monday, December
 15, 2014 10:38 AM
  Subject:
 [PSUBS-MAILIST] props
    
 Hi All,
 If I build a thruster
 with an extra long shaft, then put two props on back to
 back, one prop reversed.  Will the thruster perform equally
 in both directions?
 Hank
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