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Old Nov 30, 2010, 12:03 PM
lukibob is offline
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Propeller Design


If you could design a propeller from scratch for a multi-rotor, what would it be?

I would like to hear peoples thoughts on this subject.

Give details like diameter/pitch ratio, mass, materials.

List the improvements you would make on what you think is the best performing purchased prop.

Be creative, this is a brainstorm across the web so don't limit to what is conventional.

Innovate: multi blade, curved tip, ringed perimeter, don't hold back "stupid" ideas.
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Old Nov 30, 2010, 02:32 PM
SebastianJ is offline
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Static lift specific propellers for multirotor copters has a quite long history, sadly, no one as acknowledged the market yet, but we are slowly approaching better times, to give an example: GWS has announced the soon release of counter rotating sets of the most popular sizes of their superior slow flyer propellers.
However, those propellers are still made for airplane use, they are designed to move through the air, not to provide static lift.

The perfect propeller for multirotor use will look something like the Draganfly X6 props: http://www.draganfly.com/uav-helicop.../picture-5.php

The Microdrones props: http://www.microdrones.com/mediacenter-bilder-en.php

Or the Airrobot props (yum): http://www.airrobot-uk.com/images/pictures/lara.jpg

The blades for the popular coaxial helicopters like the Esky Lama: http://www.helibuy.com/images/helico...ky_lama_v3.jpg are usable to some extent with custom made hubs and when cut down, but only for sub 1000gr. multirotors.

Early multirotor props:

- X-UFO, 7" props, very soft almost unbreakble: http://www.x3d-shop.de/shop/article_...aid%3D85640%26

- Spectrolutions 14" props, very soft and heavy: http://www.rchelisite.com/draganflye...iew_part_1.php and here: http://www.spectrolutions.com/newwebsitearc_009.htm

- Laheli Y-ufo 7" two piece props, brilliant design, these would sell like hotcakes in 10 and 12": http://www.laheli.com/web/product.ph...0black&lang=EN

- AR.Drone, much like X-UFO, around 7": http://www.ardronehelicopters.com/ar...nt-blades.html

AR.Drone's props are designed with the help of Novadem: http://www.novadem.com/
Quite serious French guys who obviously knows what they're doing.


So much for the appetizer, let's team up, get to work and design the perfect multirotor heli propeller and find a manufacturer that's up to the task.


Please feel free to correct me if I got any of the specs wrong or if I left anything out.




Sebastian
Last edited by SebastianJ; Nov 02, 2011 at 03:57 PM. Reason: Updated links
Old Nov 30, 2010, 08:56 PM
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Tri-Quad-Hexa-Octo-copters!!
Excellent synopsis Sebastian!
Cheers,
Jim
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Old Nov 30, 2010, 09:15 PM
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Great start


Those are great examples of what exists.

I am in the process of making my first WiiCopter and needed some go-by designs for the prop. I think since winter is upon me, I will make an indoor, 10g motor with 6a esc version.

I have been making props for my planes using that motor, but wanted to know what differences should be incorporated to optimize for hovering.

I plan on designing pairs of props matched to motor size for hovering.

I like the Draganflyer design with the curved tips, I will start with that general shape. The first ones will be 3d printed in polycarbonate or ABS. I then plan on trying to vacuum form using the printed ones as forms. Not sure on the vacuum formed material.

Concerning pitch and diameter:
So far for my 3d planes, hovering is generally better with a ratio of 2/1 for Diameter/pitch ratio.

I have gotten good results for power and efficiency using less pitch like 3/1 also. I will probably start somewhere between.

I use an airfoil on the blade, with a tapering angle to maintain a constant pitch through the entire blade. Wider chord near center, and as thin at the tip to reduce inertia.

I'll try to get some pics up of the current designs soon.

Keep thinking
Old Dec 01, 2010, 02:09 PM
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Prelim pics


Here is a picture of one of the props I had designed last year.

Today I made it:
150mm dia, 50mm pitch, hub can be any bore but is 2mm for press fit onto HXT 10g motor, Chord is 20mm at wide part down to 11mm at tip

Anyone see any changes to improve on performance?

I will try to make it light as possible by thinning the sections.

I will mirror it, and print out a pair for testing.

I'll try to get some accurate tesitng done after that, amp draw, static thrust, rpm.

Matt
Last edited by lukibob; Dec 01, 2010 at 04:05 PM.
Old Dec 01, 2010, 02:24 PM
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Prop Manufacturers


If you are listening, each multi-rotor customer is using at least 3 props and likely orders at least 4 at a time. I fly quads and order 6 every time I order. I'm building an octo now so you can expect my orders to increase to 10 props per order.

Very few airplane flyers are ordering 10 props just for 1 machine. What company would ignore a customer base that will increase the product group order by 4 fold? (answer: one that's not very wise).

I'm sure you all know this but perhaps a little reminder will speed things up before spring time.

To echo bas10an, static lift designs like the draganflyer's are what I'd like. APC have been my favorite. 12x3.8 but I would like larger. Thankfully APC is kicking out 14" props too.
Old Dec 01, 2010, 09:07 PM
AXI Motor Models is offline
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Definately need turned up wingtips (aerolons) ideal for static thrust.
Carbon fiber ultra light for low inertia. For size 13" -14" is ideal.
Old Dec 01, 2010, 10:53 PM
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Quote:
Originally Posted by lukibob View Post
Here is a picture of one of the props I had designed last year.

Today I made it:
150mm dia, 50mm pitch, hub can be any bore but is 2mm for press fit onto HXT 10g motor, Chord is 20mm at wide part down to 11mm at tip

Anyone see any changes to improve on performance?

I will try to make it light as possible by thinning the sections.

I will mirror it, and print out a pair for testing.

I'll try to get some accurate tesitng done after that, amp draw, static thrust, rpm.

Matt
Matt,

How did you design this? Which airfoil did you use?

- Roy
Old Dec 01, 2010, 10:54 PM
RoyLB is offline
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Quote:
Originally Posted by AXI Motor Models View Post
Definately need turned up wingtips (aerolons) ideal for static thrust.
...
AXI,

I'm not sure what you mean by this. Do you have any examples of existing props or rotors that use this concept?

- Roy
Old Dec 01, 2010, 11:02 PM
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I would start by using this program to design for efficient static thrust: http://web.mit.edu/drela/Public/web/qprop/

Then, I'd mount the props in a thrust-producing shroud. This way you'd have all the safety of a shroud, plus a reduction in blade flapping due to translating flight, and the additional thrust would offset the weight.

- Roy
Old Dec 01, 2010, 11:51 PM
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Quote:
Originally Posted by RoyLB View Post
Matt,

How did you design this? Which airfoil did you use?

- Roy
I used my own dimensions based loosely on a Clark-y airfoil. I modified some ratios to better suit the 3d printer, but eventually sand the printed prop to a shape as close as hand sanding can to the original clark-y.

Here is the latest prototype, designed and made today!
Old Dec 02, 2010, 01:16 AM
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Awesome Work!
Cheers, John W.
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Old Dec 02, 2010, 05:20 AM
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Very nice work, looking forward to seeing you succeed in this, since there arent any options for purpose made multi rotor props
Old Dec 02, 2010, 07:06 AM
RoyLB is offline
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Quote:
Originally Posted by lukibob View Post
I used my own dimensions based loosely on a Clark-y airfoil. I modified some ratios to better suit the 3d printer, but eventually sand the printed prop to a shape as close as hand sanding can to the original clark-y.

Here is the latest prototype, designed and made today!
Nice!

How did you determine the span-wise chord (almost constant?) and angle of incidence distribution? Why did you choose Clark Y?

- Roy
Old Dec 02, 2010, 08:06 AM
jesolins is offline
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Tri-Quad-Hexa-Octo-copters!!
Nice! Keep going!
One suggestion: Round the prop tip ends for safety. The only reason that trailing sharp tip edge is put on props is to insure they inflict maximum damage to any nearby skin...
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index
Last edited by jesolins; Dec 02, 2010 at 11:19 AM.


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