Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

silent 3 bladed prop - I got the equation curves down in inventor.

by teneopreto Aug 27, 2014
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Can you make a 8x6 slow fly 2 blade? =)

could it be possible for you to make one 60mm blade diameter with a 1mm shaft hole and 4 blades?

hi there i cant seam to get it to work with 4 blades, inventor just cant hack it. Sorry about that.

alright well thanks anyway.

Hi there

I tried tomake a 4 blade version for you, this is actually not a drawn modell its mathematically calculated,
Inventor is having trouble calculating a 4 blade version, I will need to adjust the math.

I will try to see if i can fix the math.

Ok thanks! Let me know if it works.

Very promising design. We'll need a 10 foot diameter with 6 such blades for the future ultra-quiet Sky Taxis of Regional Sky Transit (see AiAA paper). Please email me if you want to get involved in that: brienseeley@gmail.com

I sendt you an email.

can you make a 5x3 Propeller - 2 Blade.
Thanks in advance

I made a 5x3 2 blade, i havent test printed it so i havent verfied if it, please let me know if its like you want.

I can adjust it if required.

Could you please make matching CW & CCW props? Am using 10x4.5 slow fly now, also please scale to fit MakerBot Replicator 2
Big Big Thanks
Super Sick Prop Too!

Sure i can try to do that, can you give me the axel diameter you want?

Schould be no problem with the build volume a 10 inch with 3 blades. Its diameter is redused so it schould fit directly into the raplicator.

Thank you i have been looking at the eurocopter, i will probably try to adjust in that direction.

Please feel free to give me some spesific suggestions for tip shape, wing profile, how the profile evolves over the lenght and any other changes along its lenght along with twist..

There are some very interesting studies you can read up on to make some awesome props. First I would suggest Pual Lipps, Ellipse Props. They are proving to gain significant thrust in the full scale world, that being said, due to the Re's at work, it may not scale very well.

Other research a little more on the lines of noise reduction would be Eurocopter (Airbus Corperation), and Sikorsky. However, much of the principles in full scale helo blades will not scale. Much of the noise and "thapping" sound come from extreme pressure differentials, and the air literally getting a "beating." Most of the current research is point towards more blades with higher aspect ratio, as well as reducing the blade-vortex interaction, which is when one blade tip goes through the vortex of the previous blade. The forward and rear sweep designs are doing a few things to reduce this, first off they are trying to reduce the size of the vortex (like winglets on a fixed wing), as well as "push" it away and underneath the oncoming blade as much as possible. Not only this but the forward and rear sweep is specifically to keep the blade edge at a better angle than directly perpendicular to the walls of the vortex. Last but not least many of the newer blades are playing a low more with reducing the pressure at the tips, just as we are with wings. for example, look at 90% of airline wings today, which incorporate some type of winglet, or wing tip device (including raked).

All this being said, I think your best bet is to simply reduce the loading at the blade tip. At our reynolds numbers, many of the aforementioned characteristics simply aren't present, or are at too small of a factor. Currently at our scale your best bet is to redesign your quad for light weight, higher aspect ratio blades on a 2 blade propeller. Blade shape should be slightly forward swept from the hub, transitioning to rearward sweep, or resembling a high sweep Paul Lipps Ellipse Prop. On top of this, your list distribution should be elliptical from approximately 10% of the blade to about 85-90%, and then reduce the loading drastically. To achieve this you may not end up with a constant twist. By reducing the amount of lift at the tip, you are effectively reducing the difference between pressure on top and on bottom of the blade. A vortex is quite simply high pressure air on the bottom, bleeding up and over the tip, taking over the low pressure air on the top, creating a vortex. By reducing this pressure differential, you can reduce the top drag/vortex created.

Equation curve.

thickchordt5(0.2969sqrt((1 in)/chord)-(0.1260t1 in)/chord-(0.3516t^31 in^2)/(chord^2 )+(0.2843t^51 in^3)/(chord^3 )-(0.1015t^7*1 in^4)/(chord^4 ))

• c is the chord length,
• x is the position along the chord from 0 to c,
• y is the half thickness at a given value of x (centerline to surface), and
• t is the maximum thickness as a fraction of the chord (so 100 t gives the last two digits in the NACA 4-digit denomination).

You need to add chord and thick as variables in inventor (the fx button) before compiling the equation curve,

PS ! The part file mustbe in inches!!!!!!

The foil must be made in 2 sections one for the top curve and one for the lower just add "-" in front of the lover airfoil curve.

Could you post the equation curve please?

I have tried to make the root 2914 the forward tip 2213 and the end is simply a point.

Its very hard for me to program the equation curve for this in inventor so i am not 100% sure that i got it right.
Actually the leading edge is a bit to sharp so im pretty sure it can be improved.

The design is taken from a swallows wing i will gladly take suggestions for improvements. Now that i have the basics down i can easily make other versions

What Foil series?

I see little twist, especially where it is critical in the rearward sweep. The entire idea behind blade tip designs is to have an elliptical lift distribution across the span of the blade, as well as reducing the reynolds numbers near the tip. Not to mention a blade or wing coming to a point is nothing but drag.

That being said, very cool looking design, and a great start!

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