Busted split prop

Took a spin yesterday with my machine and while cruising I started hearing a slight noise/note, but there was no performance degradation or red flags. So I kept going. Was flying a small full reflex size wing (20m2) and all went well in spit slightly turbulent air. Only after packing my gear away did I notice one of my blade was badly split and my guess is that the smaller section still attached to the main body began vibrating at full RPM and created the sound I heard. I have to say that I fly at sea level in a sandy environment, and the two bottom props are taking a beating - pitted/sand blasted. I concluded that the lower props must be vacuuming the sand grains and probably a few pebbles hitting the leading edged hard. I do not really care about the way they look as long as they do the job and are still in one piece. I can not change or fix my props after each flight :slight_smile:
The dozens of tiny lighter colored marks are made by the
sand hitting the varnish and removing it. I wonder if carbon blades would better take the abuse?

my guess would be that the carbon props, due to the carbon fiber being a little stronger material than the light beech wood, would withstand the “sandblasting” maybe a little longer. But in the long run, they would suffer as well.

I remember watching a video from either “Team Fly Halo” or “Tucker Gott” or both, where they were talking about just that problem…
and that solutions would be to not stir up to much sand while running, and applying a strip of clear tape to the prop, where it cuts through the air.

Hi Etienne,

I tried the tape but it did not make much of a difference because the blasting happens deep in the cord of the blades, with the leading getting hammered. It is essentially an issue relevant to that particular machine design because I have flown many times in the past in the same environment and place with gas units without having the issue. It is impossible not to stir up sand because it is deep. The only location it could be possible to do to a certain degree would be on compacted sand where fat bikes can manage to keep rolling. The vacuum behind the mini-blades is pretty intense. I guess it would be even worse for short pilots. I always shake off the sand resting on the flat bottom section of the hoop before launching. It would be a cool thing to video what happens at that moment with a high frame rate to then slow it down. I am sure we could discover interesting stuff there :wink: but 120f/s may not be fast enough.

I will do my best not to make too many toothpicks out of my props. The place we PG/PPG is called Rocky Point (name of the town) and there is an obvious reason for that :wink:



You will see even prop manufacturer put epoxy paint on carbon props -
Epoxy coat is way superior to any other paint - don’t forget to balance
your props…

I had this exact thought. That might be good product to try. Could also sand the prop coating off and lay up carbon fibre over the entire props. That’s how aviation props are typically made. My MT prop on full sized plane has wood core, carbon fibre skin and a metal edge.

ha ha ha… too funny.
I have to paramotors:
a) openPPG
b) CorsAir Black devil light combustion engine with exactly the same frame and harness like you: the “simplify titanium frame”

@tarifachris the epoxy coating is a nice find

@dzubot not too bad of an idea, to add a thin layer of carbon fiber sheet.
It would be quite work intensive and probably not too easy though,
as you need to really make sure to change the shape and profile of the airfoil…
but the work could be worth it…

why don’t we make our own custom propellers??

who wants to try first ? :slight_smile:

I’ve flown at the sand dunes and experienced the same sand blasting- and I’m tall.

Somehow there is a vacuum effect taking place close to the ground. Perhaps when we are making the transition to sitting and the hoop is closest to the sand is when the grains are sucked into the blades?

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