What are the major differences between Carbon fiber and Nylon/plastic porpellers.
I see over on Facebook that people suggest that carbon fiber props can be used on 2kg plus drones and that they are “prone” to vortex ring state and that if smaller drones are used then the nylon/plastic props are to be used
Vortex ring state is an aerodynamic condition. The material the prop is made of won’t change that.
In my experience, carbon props tend to be better quality, design and more money. So if I’m flying something over 2kg, the odds are there’s more money on the line and a better prop is worth it. Likely to have better vibration qualities as well.
If I’m flying something smaller, especially under 1kg, it’s more likely to be more robust and FPV style, so props are more of a consumable.
FPV quads tend to run the nylon props because they are more robust. I’ve bashed the hell out of my 5" quads and bent prop blades back on them selves and they didn’t break or fail. And a pack of 5" props costs something in line with a bottle of beer.
A carbon fiber prop would explode with a fraction of the abuse.
I think it’s a question of what prop is best for your use case.
I have heard speculation that carbon fiber props can cause interference with your gps signal due to being a (rapidly spinning) conductor, but I don’t believe this has been empirically tested or proven.
I had bad experience with plastic props.
Turns out material wasn’t UV-stabilised causing props to become brittle over time and suddenly snap.
How does anyone know if in fact plastic props are or are not UV-stabilised ? …suppliers make all sort of claims just to sell you something. By the time you find out it may already be to late and you’re picking up your drone in pieces somewhere.
That’s why I stick with carbon fibre or nylon props from a well known quality manufacturer.
I’m afraid the answer there isn’t very straightforward and depends on the manufacturer to use a proper plastic composition that has UV resistance. Unfortunately, carbon composite can suffer similar degradation if the resin is not UV resistant/stabilized.
Generally, you get what you pay for, and if you buy the cheapest props, you may be getting a plastic composition that is ill suited for prolonged outdoor use.
Unless the manufacturer gives specific specs, I suppose it’s a dice roll…
The major difference is the Young modus,
The CFRP prop with long fibers ( Carbon texture) is more rigid and has a bit less mass, so the flutter frequencies are higher. The nylon props with short fibers(glass/carbon) is more flexible and heavier, so lower frequencies.
Aerodynamically speaking the only difference in the attitude to deform and flutter, in geometrically equal.
So a lower vibrating prop is better suited for a smaller prop and CFRP is more suited for bigger props.
At least this is the theory, but for vibration and deformation of the prop balancing is way more impacting on the RC scale of things.
Actually that’s not far from what I did after I suspected prop failure:
I placed a spare prop outdoors for a fortnight and compared it with another spare prop which was never used. Sure enough the one left outdoors snapped when trying to slightly bent it.
That’s what was left after I found it,…9 months later:
I’ve found not all carbon fibre props are created equal just because they are CF - they dont necessarily break any easier but cheap ones are usually like a ceiling fan blade with little to no aerodynamic shape to them. So you wont necessarily get the flight characteristics you were expecting.
More expensive CF props have the correct aerodynamic profile.
I think better quality plastic props would be quite acceptible too. I’ve used plenty of typical plastic props and probably would have replaced them periodically. They seem to get chipped anddamaged just from normal use - debris flying around during landing and takeoff.
I’ve also used the MasterAirscrew MR series and found them to be above expectations as far as flight is concerned. They seem flexible and maybe softer than some plastics, although you wouldnt know it from flight. I would say they are much less likely to snap from old age or UV damage, but I havent tested that.
I think the hybrid molded props that have been appearing will be a good compromise - again, buy from a reputable source so that the glass or carbon fills in the plastic actually are there - you can usually tell from the way the plastic reacts to a blade scrape.
I would generally prefer a stiffer blade to cut down on flapping vibration noise, and generally, at the moment the better blades for tis are carbon.
as far as VRS goes, te most significant function seems to be blade pitch angle - hence vtol biased props are, generally, lower pitch than their forward flight counterparts.