Propeller Fabrication

Discussion in 'Props' started by Rickdiaz, May 29, 2016.

  1. Rickdiaz
    Joined: May 2016
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    Rickdiaz Eng.

    This is for an ultralight, so needs to push around 300 lbs I think.

    I'm looking to build my own propeller because of funding issues, and I was curious about making a propeller from a pipe because it already has an angle . I would like to know if this is feasible and the size and shape it should be.
    I'm either going to make it out a plastic like PVC or aluminum, and in the case of the PVC I would need to know wall thickness and such.

    thanks for reading, and please don't just shoot me down, I think this will work. :)
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    You do realize how difficult this will be, right? PVC wouldn't be a good choice, as it's modulus just isn't up to the tasks, unless roto molded or similar in a very precise mold.

    Propellers are a bit of art, black magic and serious flow dynamics understanding. It's not something you can just whip up in your garage on a Saturday afternoon.

    I'd strongly recommend you purchase a set of plans, based on your aircraft's needs, as there's literally thousands of types to select from. I have a fair bit of sport ship time and buying a custom carved 68x69 was about $800, the last time I did. A metal prop would have been at least three times this amount.

    I can't stress enough how important it is to get the right prop and one that's well done. The designer of your ship will have a set of engine recommendations and the appropriate props for each. There are many questions you need to answer before you start carving one up and these might include: what airplane design is the propeller for? What kind of airspeed are you hoping or? Which engine and horsepower do you have installed? What's your preference? Best cruise/top speed. Best take-off/climb/high altitude or a standard/compromise prop. What are other flyers of your model and engine combo using, etc.

    Simply put, yep you can make a prop, but you need to have a really good idea what you're making and good precision when you do.
     
  3. whitepointer23

    whitepointer23 Previous Member

    An aircraft is not something you want to have funding issues with.
     
  4. gonzo
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    gonzo Senior Member

    Or fail at high altitude. A broken blade will shake the ultralight into small pieces.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Amazing stuff. I'd make it out of lollipop sticks glued together.
     
  6. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    I'd use something like this for really inexpensive.

    [​IMG]

    They are available everywhere for quick replacement if needed and all the fine design technicalities have been ciphered out by certified propeller Engineers.

    For double the price, approx. $35, one of these would certainly be worth it. They spin much faster and have enough power to either mangle or chop off little kids' fingers, depending on how quick they react. I'm pretty quick and can hold up my scarred fingers as proof.

    [​IMG]

    I'm thinking a weed-eater power system or direct drive using one of those cheap Chinese generators, like this but smaller...

    [​IMG]

    If you are really ingenuitive and smart too, and thrifty, there doesn't seem to be any reason not to take something like this.....

    [​IMG]

    connect a fan, add extensions onto the handlebars so as to create wings and Bob's your Uncle. Being pretty low power, you would need multiple generators. You could probably mount them all around the tire. You could probably get 20 of them on there somehow, and if needed, they could be mounted on both sides for a total of 40. That should probably be enough even for some light welding capabilities, which will likely be needed for fan mounts, aileron controls and of course re-working the chain and sprocket drive system so it drives the front wheel, where the generators are.
     
  7. whitepointer23

    whitepointer23 Previous Member

    I think you need to do more research into electric fan propulsion. The aircraft will limited to the cord length and how do you prevent it getting tangled .
     
  8. JSL
    Joined: Nov 2012
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    JSL Senior Member

    Somebody tried this before (another site) using steel pipe for a boat propeller. After many hours of messing about he came to the conclusion that it simply was not worth it...... but he learned a lot and the 'prop' looked like a sophisticated metal sculpture.
    However, if you do insist on building your own prop I suggest a 'pusher' configuration so when the blades fly off they don't puncture and damage your wings (or you).
    On the up side, the money you save can be put towards extra life insurance
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Pusher setups in ultralites aren't prefered, simply because having the engine in a location, to shake hands with you on a stuffed landing isn't ideal.
     
  10. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    If you're going with a hard wired system you use this kind of expandable non-kinkable aviation wire. Also, a 220 volt supply gives you twice the range while using only half the energy.


    [​IMG]




    Going in an entirely different direction for power is this highly promising axial rotating "Elasto-Strand" stored energy system. Once the bugs are worked out, this is our most best chance of extricating ourselves from our dependence on foreign oil.



    [​IMG]
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    I would strongly recommend the ACME propellor as used by Mr Wile E Coyote. He always seems to survive misadventures.
     
  12. SamSam
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    SamSam Senior Member

    The OP might want to look here for possible answers, even though the post is from July 2014.

    This 'Metascopic' guy has remarkably similar problems with his project....


    https://www.reddit.com/r/Ultralight/comments/29laqe/propeller_fabrication/

    .
     
  13. SamSam
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    SamSam Senior Member

    I think Mr. Coyote's misadventures are due to the extremely poor advice he receives from his advisor, a feeble minded warmonger suffering from rabies...
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    Metascopic and Rickdiaz must be the "death wish twins". I would sooner make a parachute out of old bed-sheets.
     

  15. cmckesson
    Joined: Jun 2008
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    cmckesson Naval Architect

    Can somebody explain what " ...from a pipe because it already has an angle" means? What is this "angle" of which he speaks? I assume it is intended to be the blade pitch angle, but where is this "already" present in a length of straight pipe?

    Not endorsing, just trying to understand.
     
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