BE CAREFUL - very thin tips

I was setting up for my first flight, and I broke the tips of the carbon fiber arms. These are VERY THIN, may be on next design you can consider doubling or tripling the width.

see pic

just received my batch 3, and this was one of the first thoughts as well, when I got to this point with my assembly just two days ago.

That is a little worrying

I thought this was addressed in from batch 1 or 2?

Anyone have any ideas how to reinforce this to prevent it breaking?

I am thinking the tube connectors need be redesigned so they partially encapsulate these areas ,with a snug fit, and printed from one of the more sturdier plastic formula’s. That way you have some external support on the outside pushing back on the inside forces of the connector.
I tried to capture and show something but it looked like a 2 yr was finger painting :smile:

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Hopefully this looks like at least a five year old finger painting. :slight_smile:

Mine have held up for well over 100 flights but after my last flight one of mine split too. Haven’t decided how to fix mine yet but here is a simple design solution for future builds:

The tips only need two small holes for screws thus making the carbon part much stronger:

Two standoffs would go through the red plastic center piece:

Two screws would hold the nubs on each side and hold it all together.

I will likely fill my tips in with fiberglass and epoxy and then implement this design.


Its a Van Gogh compared to mine :heart_eyes:

We need to use the inside portion to come out and around the outer edges



Yeah, that might work for fixing the current design. I’ll draw it up and share my files. Future builds could be made like I proposed so that everything stays flush but this mod may bulk it up a bit. I will at least keep the transitions smooth.

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These areas need to be doubled in their height for new designs.

Other options to fix current would be replaced whole end with a metal completely and bolted to the side
or maybe a thin pieces of aluminum glued to the outside and inside faces


That’s similar to what I was thinking as a fix for the current design.

Nothing would need to be doubled up for future designs with my proposal though. The carbon would be cut to look like this which would be plenty strong:


ok - now I get it - yep, that is perfect!

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Don’t the red plastic things need to be curved?

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Yes, the tips need to be angled ever so slightly (it’s a 5 foot diameter circle). I drew this with an app on my phone just to put across the concept. I won’t upload files without testing them first… notice I haven’t uploaded the files yet?


@GliderPilot two thumbs up! your contributions to the OpenPPG design (electrics, frame…) are just awesome!

Just wanted to say it once more :slight_smile:


How was the design flaw overlooked by the original designer? CF isn’t magic. lol
GliderPilots redesign looks great only problem is when you curve it how will it be attached? curved bolts?
The inside of the 2 arms needs to be shorter so you can bolt it on there then spread them apart and pinch a short tube section in the middle and use the spacer in the original design to hold it together.

I’ve been developing my own eppg and already accounted for this before building.
sorry if i sound condescending at all. Im interested in helping where i can.


The long piece in my drawing is the center piece. You took my drawing and turned it inside out. There is absolutely no need for curved bolts. What you are calling a spacer is a standoff and there are two through the center piece. It eliminates the need of the current standoff making a very clean design. Here it is without the curve which is gradual enough that bolts will fit:


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My hack for protecting the thin carbon rings at the ends of the arms from damage: cut up some 3/4" ID thick vinyl hose.

The damage isn’t caused by scuffing it but rather from the forces acting on the connector so I don’t see how that tubing will help counter those forces.

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Here are some views with the curve: