Propellers and Ducts


#251

Hi @axgib , what is the motor type you attached to this smaller prop (as I can see it is about 109mm diameter), I think to try double motor setup with those two props. Please provide your motor details and power you matched to this prop, which are below:

I just thought it would be great to scale this one down so it can be used with @pacificmeister 's build so here it is http://a360.co/2BwRWhb http://a360.co/2DH3zYC
The second one is the same but I just kept the 9.6mm sided square hole

the scaled prop on the left, the original @tunnelvision on the right


#252

A propeller made of plastic on a 3D printer will have very little efficiency. Plastic blades will bend at max RPM, so they must be thicker than blades of aluminum, steel, carbon, titanium. The ideal blade must be very smooth and solid!


#253

Not really. My SLS nylon printed prop is slightly flexible and has a slightly rough surface. Still does 40kph. It probably would be faster if it was aluminium, but it certainly does not have to be. PC is also tough.


#254

Slightly flexible blades and a rough surface may not affect speed, but will reduce efficiency. Reducing efficiency reduces the length of the trip.

I have a propeller for racing boats on the table that has a speed of about 180 km / h - the blades are smooth as a mirror and hard as steel. It is not possible to print such a propeller from nylon.


#255

Yes your right. When my foil gets to 180 kph, I must use smooth hard steel.
:roll_eyes:


#256

Your propeller has an efficiency of about 5%, aluminum should be about 10%. If you need low efficiency propeller, you really do not need either aluminum, carbon, steel or titanium.


#257

Please be constructive, show us your design instead of teaching people that already run e-foils with proven designs. This forum is not about designing the theoretical optimized setup but rather to exchange ideas and experience, so I suggest you either contribute or stop spamming the forum.


#258

My opinion that it is not possible to produce a high-quality plastic propeller on a 3D printer for e-foil using FDM is not a spam, but a very important consideration for every builder (even for you). I recently printed a high-efficiency propeller and is totally unusable for propelling each vessel because the blades already bend at very low RPMs. If I made the blades stronger, the propeller’s efficiency would decrease. The efficiency of each propeller is the most important parameter !!!


#259

@Dynamik I agree that a 3D printed propeller will never be as efficient as a CNC prop, Cast aluminium or even plastic injected moulded plastic .
Some of us use 3D printer props as we develop just hobby efoils for fun.
Can you post details of a more efficient efoil prop option that the group can discuss ? or purchase. Some time ago we were promised another super efficient design by another propeller expert user name was “WNT” but I do not recall seeing any updates.
You may want to contact “WNT” and work together if you & WNT could work together we may see some excellent new options on the market. :wink: I will buy one & review it.


#260

Yeah it is SPAM @WNT, @Dynamik or whatever other name you want to go by! All people here know that 3D printed propellers are not high quality or optimised! You just continually stating the obvious!
However, 3D printed props are CHEAP, easy to make design tweaks to and reliable enough to get all of us that actually do foil for fun. My prop cost me about £2 to print. It’s still working and having fun.
Why don’t you design some open-source props for this community and then people can print, mould or CNC them and test them out. At least that way you’ll add something constructive!!!


#261

Hello high speed prop…


#262

I was easily able to get an H105 profile on my 8cm chord 3D printed propeller without increasing the thickness. If I went any thinner i would be losing L/D.

Maybe it flexes under load, but why is this bad? Don’t you want to get as close to an elliptical loading profile as possible? i.e.decreased tip loading. (look up oswald efficiency in your aero text book).

Or just look at the wing of a 787 while it is flying.

Surface roughness: would like to see some data for this claim as well. How do you know you aren’t renergizing the turbulent boundary layer and preventing separation or a laminar separation bubble?

Are we not operating at a totally different reynolds number than your race boat? Why does it matter if the propellers dont look identical.


#263

Did you tested the 150 model ?, I looking for a good alu prop, since now all the one found are too large diameter, any suggestions ?