New Propeller Innovation: Looking for Comment/Interested Parties

Discussion in 'Boat Design' started by moobradidi, Aug 24, 2016.

  1. daiquiri
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    daiquiri Engineering and Design

    First you'll need to figure out the possible market for your prop.

    In the aviation industry, the variable-diameter prop (I'll abbreviate it to VDP) has been proposed for convertiplanes, because of the high variability of conditions in which their propellers work.
    During vertical landings, take-offs and hovering, they are highly loaded and hence inherently very inefficient and noisy.
    During cruise flight, they can be optimized for fuel efficiency, autonomy, endurance ecc.
    At max speed, the high-diameter propeller can have certain blade areas working in transonic or supersonic regime.
    The operative mix of these conditions make it very difficult to optimize fixed-geometry propellers. Hence the variable-pitch rotors are used, and VDPs have been proposed - with no practical applications yet for the latter (as far as I am aware).

    In the marine ambient, the supersonic speed is never attained - it is replaced by cavitation issues, which arise under similar conditions (high blade speeds or high loadings). I don't see it as a problem in your case, because the purpose of the VDP is to keep the disk loading low, which works against the cavitation. The root cavitation and vibration (which will be low, due to a low fluid speed in the root area) can be dealed with a good hub design, IMO.

    The marine growth is a major problem. It is too often under-estimated by inventors of novel and mechanically complex systems. Marine growth and rust can disable even the most ingeniously conceived mechanisms in very short time, or can drastically increase the maintenance costs required to keep them running. For this reason, simple fixed-geometries are by far the most preferred ones in the boating industry. Simple and cheap is what a leisure boater wants.
    The more complicated systems are for commercial uses only, and only if their economical benefits by far outweigh the downsides.

    That's why you'll need to more precisely pinpoint the target of your invention, and the leisure boating is not the one. Hence, if I were you I would not think too much about outboard motors, and would rather concentrate my efforts on large commercial users with inboard or azimuthal drives.
     
  2. moobradidi
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    moobradidi Junior Member

    Excellent comments and thank you for taking the time to provide them.

    By the term "convertiplane" I assume you mean the range of aircraft that vary their lift geometry- but that includes lots of concepts and one could even stretch it to include very conventional designs like jump jets.

    However I assume you basically mean tilt rotor and tilt wing designs.

    Our innovation would work well in a tilt rotor application but not well in a helicopter design. The reason is that placing our prop/rotor in a vertical position to provide horizontal blades and hence down thrust (in helicopter mode) would expose most of the blade support structure and create unacceptable levels of drag at high speed.

    However tilt rotors spend most of their time flying as aircraft do and only tilt the rotors for landing/takeoff - where speed is low and drag is less of an issue.

    In a conventional aircraft horizontal prop orientation, the support structure in the hub area is also horizontal and drag is not so problematic.

    Clearly the ability to have max diameter rotors for take off and landing and minimal diameter for conventional flight would be a huge advantage, however the complexity of most tilt rotors are already on the edge of nightmare so it would be a tough sell to integrate this with dual wingspanning driveshafts and double gearboxes.

    Your comments on cavitation are heartening and quell a little of my trepidation about the outcomes of any hydrodynamic analysis we will have to get done (sometime).

    I don't fully understand your comment about marine fouling. If it is likely to be a big issue then I would have thought that the recreational market would be more appropriate given that a larger % of these boats don't live in the water and are washed after each outing.

    The large marine applications have competition in the form of nozzles which as i understand it are really ducted fans/shrouds that work similarly to high bypass jet engines i.e. the shroud scoops in a big volume of air/water and the diameter constriction accelerate it out the back.

    These are growing in popularity in europe and offer significant gains. I doubt they would be compatible with variable diameter props since they are static and tip clearance is a big design factor.

    In general it has been very difficult to make contact with marine designers and research outfits. The europeans are most definitely the world leaders in innovative prop design- I think the US has had cheap fuel for years and the efficiency push has not been nearly as crucial. However the contradiction of the internet is that it also has walls to counter its access. Most web site addresses take u to a web admin, media or marketing person.

    Even with direct contact with their research labs there is a very evident air of "no big risk". An aerospace academic told me that the only money available these days was for drones and the majority were small startups with no r&d budget.

    A relative working for rolls royce jet engines revealed large cutbacks.

    In an environment of historically low oil prices and huge levels of debt there is little appetite for a complex and high risk r&d project when companies are finding it hard to sell what they already have and know will work. A project failure could tip many such companies into liquidation.

    Anyway, thank you again for your insights. Very useful.

    We will soldier on and enjoy the journey.

    cheers.
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Outboard motors are way too difficult because it would require a complete re-design of the lower unit to accomodate linkages, and you have the problem of exhaust running through the guts of it.
     
  4. moobradidi
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    moobradidi Junior Member

    The only redesign is the addition in terms of controls is an extra linkage oriented the same as conventional forward-reverse gear shift mechanisms. It can easily accommodate 2 in a standard lower unit.

    As for a through hub exhaust, not a problem. If I could show u the mechanism you would understand but understandably, I can't.

    Thanks for your comment.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    The only reason you are here is to to snaffle "investors". You have nothing to show them though. Mortgage the house.
     
  6. moobradidi
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    moobradidi Junior Member

    I forgot to add- in the version where diameter and pitch are operated by a single control- in its outboard implementation it just replaces the forward-reverse link run that runs vertically on most engines.

    Obviously you don't need a forward-bakward gear and dog clutch when you can engage any degree of forward or backward thrust.

    Problem solved. In fact even with independent diameter and pitch controls the shafts just run next to each other in the same orientation as a gear shift shaft.
    You could put 10 in there and have room for more.
     
  7. moobradidi
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    moobradidi Junior Member

    We have solidworks models we can email them at this moment. They are dimensionally sized and are in a CAD package format that is industry standard. Indeed no engineer would pay attention without such models.

    I believe you are upset because we're reluctant to show just anyone the details of our mechanisms.

    But it has to be that way for obvious reasons.

    I'm sorry if that frustrates you and I understand your scepticism but we're interested in the input of people both positive and negative and a lot of it
    confirms some of our own doubts.

    In other cases we have had revealed to us (which we didn't know about) a product that has some similarities to ours but which we think is not as capable.

    That's very useful.

    Truthfully, ALL publicity is good publicity and if it makes you feel better than I would welcome you telling people about a ***** who thinks he has a designed a variable diameter prop.

    The more people who know of our stupidity the better.

    Honestly sir I wish you no ill-intent and hope that this thread has at least provided you with some amusement.

    Good luck to you and please enjoy the rest of your day/night.
     
  8. moobradidi
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    moobradidi Junior Member


    I thought you might be interested in this product which I was unaware of.

    http://www.torqueshift.aeromarine.com/

    But it basically uses a centrifugal clutch which would be subject to slippage whereas our own design(s) have mechanical linkages capable of accepting large control forces.

    Have a nice day.
     
  9. moobradidi
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    moobradidi Junior Member

    Sorry, looks like I posted to myself!

    See my other post and reference to this:

    http://www.torqueshift.aeromarine.com/

    regards
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    You need an on-water demonstration unit. In a test on smooth water, you should be able to adjust engine rpm, up and down, without touching the throttle.
     
  11. moobradidi
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    moobradidi Junior Member

    Good point.
     
  12. moobradidi
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    moobradidi Junior Member


    If you look on the website www.ndjen.com I have posted an outboard lower unit mockup. Yes the blades are wrong and the range of movement is too great (aesy to restrict).

    That model shows me directly manipulating 2 control shafts to independently control pitch and diameter.

    I have kept the video small and fuzzy for obvious reasons but it shows that the internal connections produce the desired effect. It would be easier to demo once I have redrafted the blades to suit.
     
  13. portacruise
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    portacruise Senior Member

    Hope above comments help.

    PC
     
  14. moobradidi
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    moobradidi Junior Member

    Very insightful comment and I'm a bit embarrassed that we haven't done much in the way of business planning.

    I guess it's the nature of inventors to just want to solve technical problems and leave others to think thru the dollars.

    I have to admit that has been a real inadequacy we need to address.

    It's just not as fun as moving bits of metal!
     

  15. FAST FRED
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    FAST FRED Senior Member

    "Obviously you don't need a forward-bakward gear and dog clutch when you can engage any degree of forward or backward thrust."

    This is common on CPP already.BUT! Their operation is somewhat a PIA.

    A warm operating engine will have a nice slow steady idle.

    A cold engine on starting will need a couple of hundred extra RPM for a few min to stabilize.

    If one shuts down at warm idle there will be boat motion on cold startup at idle..

    The operator has to adjust the RPM to the cold idle speed with zero boat speed before shut down .

    No big deal , after the first few exciting starts!

    May be a few hundred more lines of code for the brain box.
     
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