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Designing Propellers

ankit_khandelwalankit_khandelwal Member Posts: 8 EDU
in Using Onshape
Hello,

I am trying to design a custom propeller for a quadcopter. I have found that I need the propeller to have a diameter of about 3 inches and the propeller must have a pitch greater than 4.8 inches. How can I design this propeller and be sure of the measurements?

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    owen_sparksowen_sparks Member, Developers Posts: 2,660 PRO

    Hi, and welcome to the forum.

    I'm sorry but that's too vague a question to offer any sort of useful answer too.

    Please have a look at the suggestions in this thread and then get back to us, I'm sure somebody will be happy to help you out :)


    Cheers,

    Owen S.

    Business Systems and Configuration Controller
    HWM-Water Ltd
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    brian_jordanbrian_jordan Member, Developers Posts: 139 ✭✭✭
    @owen_sparks I suppose if I ask how to make a model of Everest to scale you'll say this is too vague?  ;)
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    billy2billy2 Member, OS Professional, Mentor, Developers, User Group Leader Posts: 2,014 PRO
    edited August 2018
    @ankit_khandelwal please upload a picture of the blade and it'll make it easier to help you.

    Me, I'd loft a surface to get the blade's pitch. Probably do another for the blade's bottom allowing me to easily make them different (top not the same as bottom). I'd then trim both back to some normal profile sketch. I'd then create a transition surface patch from top to bottom. I'd then enclose them all together and then create the mounting points using solid commands.

    I'd probably be careful when creating the loft sketches allowing me to drive with configurations. I could then have 'high lift blades' or 'efficient blades'.

    I'd probably try to get @philip_thomas to help and get a dose of propeller design theory.

    This is how I'd do it.

    But, without a little more help from you, like @owen_sparks says, it's kinda hard to help you out




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    larry_haweslarry_hawes Member Posts: 478 PRO
    Maybe this will help...

    https://www.google.com/search?q=propeller+onshape&oq=propeller+onshape&aqs=chrome..69i57j69i60j0.3940j1j4&sourceid=chrome&ie=UTF-8
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    ankit_khandelwalankit_khandelwal Member Posts: 8 EDU
    So for everyone who has responded, thank you for your time. I understand that my original question was a bit vague so I'll rephrase. I have found a public propellor that someone designed, link is https://cad.onshape.com/documents/58284b1da68076104d2c68f9/w/892463966dbe82691b7a0e41/e/24fa82ac419e32f4645448bd. Can someone please tell me how I could measure the pitch of this propellor?

    I found this link (http://www.propellerpages.com/?c=articles&f=2006-03-27_manual_pitch_measurement) on how you can measure the pitch of an actual physical propellor with protractors and by drawing some propellors. However, I want to be able to take the the pitch measurement in Onshape before I go to 3-D print it. Can someone tell me how I could replicate the procedure in the link above in Onshape?

    Thanks!
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    ankit_khandelwalankit_khandelwal Member Posts: 8 EDU
    I just saw this but when you are making a helix on a cylinder, it is possible to enter a helical pitch when you select Height and Pitch. Is this the same as a propellor pitch, because this could make my life super easy?
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    konstantin_shiriazdanovkonstantin_shiriazdanov Member Posts: 1,221 ✭✭✭✭✭
    I have a doubt that "proper" propellers are made to keep the constant pitch along the blade length. The target characteristic of the propeller is the thrust force for a certain rpm speed, so If i where a propeller designer i would easily sacrificed the constant pitch if it would give me some more thrust. My reason to think so is that you have a variable linear speed of rotation along the blade and optimal pitch for a one radial distance may be not as optimal for another. So I think the best parameters to dial with would be the distribution of an attack angle along the blade length. Though if you want a simple constant pitch blade without aerodynamic shape profile built in Helix feature is what you need.
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    ankit_khandelwalankit_khandelwal Member Posts: 8 EDU
    @konstantin_shiriazdanov I just realized you are correct. Propellor beads are meant to have varying pitch because the closer you get to the hub, the faster the angular velocity. As you said, you need to distribute the angle of attack but I'm not sure how to do that in Onshape? Any suggestions?
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    konstantin_shiriazdanovkonstantin_shiriazdanov Member Posts: 1,221 ✭✭✭✭✭
    @Dr_ND_Martin has an aerofoil feature which could possible be applicable for you. Also you can search for Variable section sweep custom feature. It make a sweep of some sketch profile, varying its parametrized dimensions by the graphic law
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