The Controllable Pitch Propeller, a summary.

Discussion in 'Props' started by apex1, Dec 26, 2009.

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  1. apex1

    apex1 Guest

    This thread was titled "a summary" not "wild guesses and assumptions"

    Experience from thw www and pictures is´nt exactly what the community here calls expertise!

    And what is a small boat? That is pretty relative, yes? (and you ask ME why you do´nt know a good propulsion system in the US?)

    Read the thread before you comment, it was almost all said already!


    Thuddy
    there is no such "constant speed prop" except you call a CPP being one, but that would not be a proper setup for efficient operation.

    Regards
    Richard
     
  2. thudpucker
    Joined: Jul 2007
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    thudpucker Senior Member

    Nope Rich, they are two different things.

    Constant speed prop's (CSP) are regulated by speed and flyweights. The faster they go the richer the bite! (0r vice verse in some operations)

    Controllable Pitch Props (CPP) the Pitch is mechanically controlled by the user no matter what the RPM is.

    In some Aircraft you can lock the Constant speed prop in full Rich or Full Lean.
     
  3. apex1

    apex1 Guest

    When do the people get it that we are not talking aircraft here? That is a completely different world and there are not really similarities, although it sometimes looks as if!

    There is NO constant speed prop, period.

    And please, do NOT tell me what a CPP is.

    Regards
    Richard
     
  4. thudpucker
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    thudpucker Senior Member

    Your pretty quick to split hairs Rich.
    Constant speed props are everywhere, including old dutch windmills. They came from your part of the world.
    However on BOATS, there MIGHT not be a Constant speed prop. I don't know of any.
    The common mis-conception is the letters CPP stand for all that variable stuff and I made the point that CPP is Controllable Pitch, not Constant speed.
    Whether each or both is used on boats is another subject.:)
     
  5. apex1

    apex1 Guest

    Who is splitting hairs Thuddy?

    This is a boat and yacht related Forum! The threads usually are accordingly related to boats.

    Windmills lawnmowers and aircraft are not what I was talking here!

    CPP does NOT stand for anything but what it means! The lack of knowledge about the topic, especially in the US of A, does´nt change that.

    And constant speed props do´nt exist on boats, that easy is it.
     
  6. jonr
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    jonr Senior Member

    More summary: In a small boat, you generally can't buy a CPP if you wanted one and if you could, it would be more expensive and add complexity. If you almost always operate at one load/speed point, it will reduce efficiency (and engine life).
     
  7. thudpucker
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    thudpucker Senior Member

    Back to the WWII sub chaser with CPP's.
    That was a 110' light footed dancer.

    Out on the water, you left the Throttle up to 1800 Rpm and did all the work with the two CPP levers.
    It would leap into a turn or make an almost 90* turn at flank (about 30 Mph)
    and would back into any alignment you wanted.
    All of that with the engines running at peak.
     
  8. apex1

    apex1 Guest

    No, sorry! More drivel only.

    What a complete nonsense. Did you ever operate a boat?

    Do you have the slightes clue what a CPP is? Complexity? Compared with a gearbox, a CPP is much simpler.

    Go, learn about the topic before you post such nonsense.
     
  9. apex1

    apex1 Guest

    Could we please stop this unexperienced drivel?

    When there are questions ask them. When there is a comment based on knowledge post it.

    But stop talking crap please!
     
  10. thudpucker
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    thudpucker Senior Member

    You lead the way Rich!
     
  11. dskira

    dskira Previous Member

    This is a misconception. You can buy all the CPP you want in the US.
    The problem is the US boat journalist do not know they exist, the boat dealer in US do not know they exist, most boat builder in the US do not know they exist, therefore people like you can't have information. But for the people who knows (I am puting a CPP on a aluminum schooner I design for an US customer) the CPP is around the corner, and not more expensive. Did you buy one lately?
    As for the complexity why you says that? did you put one in a boat in your life?
    Do not assume, don't follow the crowd, jus do your homework, and talk to people who knows what they are talking about.
    As for the efficiency perhaps go talk to a fisherman in the Baring Sea. But be careful you are at risk to receive a crab on your noze :p
    Seriusly go make a good resarch and mostly try one. It will change your life
    Cheers
    Daniel
     
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  12. RHough
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    RHough Retro Dude

    I agree. It would be nice for someone that understands propeller design to post in this thread.
     
  13. apex1

    apex1 Guest

    Well you got it!

    That was exactly what I meant with CRAP! Dumb and offending comments, thats all you have to provide.

    What do you think I´m a butcher by profession, and post this summary out of the blue?
     
  14. RHough
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    RHough Retro Dude

    I asked a question *after* I took look at the links you posted.

    I got an insult reply from you.

    You insult other posters repeatedly in this thread and others.

    I happen to know a bit about propellers and the dynamics of foils in fluids. I have never insulted you.

    While I find many of your posts offensive, I've never attacked you.

    What made you think that I was referring to you when I posed the question? If you design propellers professionally I missed that in your profile. :)

    It is okay for you to say in a multihull thread: "You are right. And I am not really completely biased. But sometimes it tickles me to bother the multi league" But when I toss a little offhand comment into your thread you fly off the handle?

    So thanks for the negative rep, do you feel better now?

    When was the last time you had the bike out for a ride to clear your head?
     

  15. Marco1
    Joined: Oct 2009
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    Marco1 Senior Member

    This guys have been making small variable pitch props for a century or so. They may have stopped making the engine but are still making the gear and shaft for small diesel engines. What's all this talk of not being available and only for big engines? It may not be commercialy viable in the US. It is certainly available if one want's it bad enough. Some even pop up on ebay.
    By the way... I thought the hair and nail pulling debate was restricted to the climate change thread. I see I was wrong. You guys sure know how to have fun!:D

    [​IMG]
     
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