Carbon Fiber Prop Bulk Order

The props are thicker in the center, and it only leaves 1/2 inch of threads for the nut.

I purchased two different styles, the ones with the sharper tips are supposed to be quieter- we’ll see.

My wood props get dinged up all the time, and probably should get some covers like dzubot use.

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The covers are made from felt yes. Also made a nice case for the loop. If anyone is interested in some prop covers she said she would be okay making some. $25 set (four prop covers) plus ship.

Let us know how these props work, very interested in them.

I’ll take some. Is that with or without the cover for the cage peices?

She says would be $20 for the loop case/cover. So would be $45 for prop and loop covers plus ship. You can pm me

@jrsimple
did I get that correctly, that your two left rotating props have a different shape than the two right rotating props, even though the specs (22x10) are the same?

how does that work for you?

I just googled “engel super silencer” and found this german company:
https://www.engelmt.de/mtluftschrauben-spinner-und-zubehoer/luftschrauben/super-silence

I am going to give them a call next week (I am in Germany as well) to find out what the difference between the “22x10 electro” and the standard “22x10” prop is.

also interesting: they have left and right rotating for the standard props, but apparently not for the “electro” version

… just found this: https://www.rcgroups.com/forums/showthread.php?578603-difference-between-electric-and-fuel-driven-propellers

some insight into what is different between props for combustion engines and props for electric engines

Yes, those are the ones I purchased, and they do have different profiles but are 22x10. From what I read, it is okay to use gas props on electric, but not the other way around. It turns out they are wood internally.

I milled out the props to mount to the motors, but the carbon fiber is very smooth, and I need to get washers with more bite to keep the prop tight.

I’ll update the post when I test them out.

Cheap thrust test using legos. https://youtu.be/TTui3shLRPk

Interesting
Did not know Lego had progress so far - LOL
Cheers

Open source thrust stand:

20 kg sensor:

https://www.amazon.de/ILS-Module-Aluminum-Weighing-Arduino/dp/B0768CN3T9

Aluminium stand idea from other product:

Another setup with bigger rotors:

I really had to torque down the carbon fiber props, and in the process broke the prop mount shaft. :frowning:

I just noticed that the newer mounts have round holes. I could thread them for mounting the props like you did on the first picture.

My plan was to put helicoil inserts in - like these:


How many mm are the holes?

The holes are 6.5 mm.

So I just spoke to someone from the “Engel Modellbau”.
She said

  • they don’t make the props themselves, but that they are made for them.
  • only the center part has a wooden core, the blades are hollow inside, with carbon outside
  • the E-Version (which they only have as CW, whereas CCW is not available) is simply thinner on the blades and on the center piece, since electro engines don’t have any vibrations
  • they also use the standard “gas” props also mostly for their own electro applications - there is no difference in efficiency between the e and the gas version other than the e-version being a little lighter.

I think for now I am going to stick with the wood props :slight_smile:

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After some testing with various locknuts, lock washers, etc., I finally found a way to hold the carbon fiber props on. Even a locknut with a serrated head-flange would get backed out on two of the counter rotating motors. A simple neoprene washer between the prop and the motor mount applies enough friction to keep it in place. I learned the hard way, only tighten with as much force as I can resist by holding the motor by hand. Using a crescent wrench to hold the motor shaft allowed me to apply too much torque.

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First Flight Test Results (initial observations only):
-Sound: a little lower tone, but not noticeably louder or quieter
-Thrust: took longer to take off and seemed to have less of a climb rate than with the wood
-Performance: they seemed to spin up faster than wood, which as we know is already a bit too fast

So I had my first emergency landing (after 5 minutes in the air)… I think the rubber washers got hot and started to tear apart allowing two props to come loose (both on the right side). I was at max power, and as soon as they got loose I felt a strong clockwise rotation that easily corrected when I let off the power.

Staying at 50% - 75% power I was able to get back to the LZ without any twisting. I guess that answers the question of what will happen if 2 motors fail on the same side.

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If the holes are little over 6.4mm you can still use 6mm stainless steel helicoils!

Then use 4 x 6mm inbus screws and use as a washer these balance rings

- maybe you have to drill 4 x new holes to the balance ring, since original it is 30 mm and it looks like the open ppg extension has maybe 28 mm circle holes…
I think the 4 x 6 mm prop screws will be much stronger than the 10mm single…

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So these were the same pitch as the wood ones right? Are they narrower? What is the weight difference?

Have you given up on these? What ever happened to the idea of screwing something into the standoffs instead of using a rubber washer?

I decided to hold off until I had a better way to attach them. After breaking a standoff I tried drilling and inserting the helicoils to the broken standoff as practice. It added weight and was hard to align the prop perfectly. Now that I can easily repair the wood ones, I’m less motivated to keep trying to mount the carbon fiber. Plus my flight with the carbon fiber didn’t seem to improve much on the wood (sound, performance, etc.).

Yes they were the same pitch, but from the pictures above you can see that the pushers were a slightly different profile than the pullers. The weight difference is: 0.9 or 1.4 oz more than the wood (depending on which carbon fiber profile).