"Duo-Prop" Inboard Transmission ????

Discussion in 'Propulsion' started by ATMHC, Jun 26, 2007.

  1. ATMHC
    Joined: Jun 2007
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    ATMHC Junior Member

    I heard that an Italian company recently introduced an inboard transmission that puts two counter rotating props on a single shaft. If anyone can help me verify this and help me find this company I will be very grateful.
     
  2. Nojjan
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    Nojjan All thumbs...

    Its actually a Swedish company and the product is called IPS !!! ;-)
     
  3. ATMHC
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    ATMHC Junior Member

    Re: Nojjan's reply:

    "Its actually a Swedish company and the product is called IPS !!! ;-)"

    Wrong !

    I'm talking about an 'INBOARD TRANSMISSION" which could be used with a single engine / traditional shaft layout with one set of counter rotating props just forward of a rudder.. NOT the Volvo IPS which is an articulated pod drive which only works in twin engine installations...
     
  4. Nojjan
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    Nojjan All thumbs...

    Sorry, it was a small and apparently not so clever joke, hence the symbols ;-) , wink, wink !

    Anywho, the duo-prop has been tried on inboard configurations before, not sure what company (maybe it was ZF Padova). The problem was that appendage drag was increased due to thicker over-all diameter of the outer "sleve/shaft" as well as bigger bossings on P-brackets etc. Also, the complexity of it all made the cost too high. If this new system that you refer to is more efficient, cheaper and easier to install I am sure it will become popular, I have my doubts though.
     
  5. KnottyBuoyz
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    KnottyBuoyz Provocateur & Raconteur

  6. Pericles
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    Pericles Senior Member

  7. brian eiland
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    brian eiland Senior Member

    Duo-Prop Chain Drive Unit

    Not exactly sure what you mean by 'transmission' and 'single shaft'??

    If you have a duo prop arrangement on a single rotation center I believe you MUST have concentric shafts...that's two shafts, not a single.

    Could a 'transmission' be much simiplier than one gear driving two pinion gears as in most outdrives?

    Or maybe you might have a look at these duo-chain drive I propose here:
    http://www.runningtideyachts.com/dynarig/Tennant_Hull_V_ChainDrive.php
     
  8. FAST FRED
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    FAST FRED Senior Member

    The counter rotating props (any brand) are claimed to get 30% lower fuel burn .

    This is nice for a boat designed to run at a relativly fixed speed where the props can be optomized for the vessel.

    I have read about a "pre swirler" that was claimed to swirl the water before the prop, making the prop more efficient.

    Sorta like the Stators in a jet , but forward, not aft of the prop.

    Anyone have info on this?

    Am convinced that a 2 speed tranny and adjustable pitch prop would allow best engine loading at the cuise speeds I am willing to pay for.

    But the more efficent the better!! 20K 5nmpg

    FF
     

  9. brian eiland
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    brian eiland Senior Member

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