We see a lot of assumptions out there about props etc, but very hard to find hard evidence and factual data. The data I have been searching for over the last 6 months is to find proof whether Carbon Fiber props are really so much better than plastic, or wood props that everyone is claiming they are . Lots off people simply assume they are better, but where is the hard evidence and data?
I see so many people claiming because CF is stronger and more rigid it it has to be much better ("woohoo! its made from CF, so its got to be the best!" mentality at work)
But that's not always the case that more rigid is better and when I ask them to back it up with testing data , so far no one has been able to point me to this.
I really think that the importance of a given "optimum flexibility factor" for efficient thrust and flight stability is being over look big time here in prop designs .
In my multirotor flying experience, I am finding I get better flight times out of plastic props than CF props. I also notice a more softer forging behavior using plastic props where as CF props give a more jittery feel.
My thinking "hypothesis" is the more flexible props work like a shock absorber and take up more easily any sudden changes in the air traveling over them. Thinking along the lines how a car shock absorber works to make a smoother ride compared to a solid fixed axle.
This also allows the motors to work less hard and so reduces the power consumption which is also the same for a car. This is just my theory on it at the moment and simply based on my own flying observations.
After switching back and forth from plastic to CF props a number of time now, it certainly showing some evidence CF props are less efficient.
I would really like to find some actual side by side testing data on the different types of props and the materials they are made from. So far Ive not found any to date. Can anyone one help?
Lastly I'm looking for 15" props other than CF made props. I have a large 80cm hex that uses 15x5.5 CF props and I wanted to test is using plastic props, but its nearly now impossible to find and large size multirotor props other than CF props.
The only one Ive found to date are these Hobbyking Multistar Wood props. Any tips where to find 15" multirotor plastic props?
Im still looking around for good quality wood multi rotor props if anyone can point me in the right direction.
I think there are still to many assumptions about CF props and we are still a long way off to find the best balance of material type for props and in particular for multi rotor aircraft's.
My feeling is CF props are simply to stiff and this shows up in the reduced flight times compared to plastic props which is what I usually find to be the case. So if they have reduced flight times, then in my book this is obviously a reduced efficiency
How I originally came to this "epiphany" and that encouraged me to research this further was while watching an eagle thermaling outside my balcony one day and I could see his wing tip feathers flexing as they help to absorb sudden changes in the air lift. Obviously this flexing helps with his flight stability and to also to make it less stressful for the eagles wings, and so it would also have be much more energy efficient. My thinking is on how nature evolves, if stiffer was better, then the eagle would also have much stiffer wings.
I would like to see a lot more testing and R&D in this direction. I think we need something in between where we have good durability , but with just the right amount of flex. Maybe the woodies will do this, but yet to give them a good test. . Even my local supplier who has been flying RC for 35 years quietly one day whisperer to me, "CF props are crap and if I can get hold of some good multi rotor Woodies, they would be the best".
I know one anyone cons with the CF porps is if you crash, they can fracture, but you cant always see it until you fly off again and then even after a few min into the flight suddenly a blade will go flying off. Its happened to me quite a few time in the early days. If you crash, then any small marks on the props should be a flag to really check closely for any fracture. I usually just replace them now days. But fortunately I crash a lot less now days to.
It was a very interesting observation on some of the DJI forums people tried out CF props on the Pantoms, but then mostly all migrated back to the soft plastic props, most finding the flight times weren't improved at all and in some case the copters were a lot less stable.
I was wondering how the wood props would do. I have a 680Pro extended and was flying GemFan14" and had trouble with Altitude skyrocketing. I spent a lot of time ensuring they were balanced to ensure vibration was minimized. I switched to 15" CF props and the issue completely disappeared which has me a bit baffled as to exactly why. Both sets of props were balanced. I expected an increase in flight time also, but maybe only see a little.
What size motors and type of battery do you have Bobby?. It may just have been a miss match? Check out this video that shows an example how a bigger prop setup is more efficient.
Also I think the cheap Gemfans are not very well made props. There is a massive difference jumping from say cheap plastic props to a larger size CF prop.
Ya, I went with the cheap GemFans just to get going until I was far enough along understanding everything. This is my first build after starting with the Phantom. I am RCer from the 90s who went on a long hiatus after having kids and just now getting back to everything. Wow did things advance! I have SunnySky 3508 580kv motors which should do just fine with the 14", but something is definitly better with the 15" CF. Even the CF ones I have are the "cheaper" Rangevideo version, but wow what a difference they made in in AltHold or Loiter mode. I am still guessing it was some kind of induced vibration even though the GF props were just as balanced as the CF ones. I am not good yet at analyzing the log files out of the PixHawk. For batts I went with the new Multistar 10C 2x5200 maH and easily getting 28 minutes with mobius camera and FPV transmitter. As cheap as these batteries are, I have been pushing them quite low, so we will see how long they last. I am fully outfitted with telemetry and pay close attention to land before I hit critical voltage, but I do push it more than most just to see how many flights I can get while pushing these batteries. I may be the only one pushing them as far as I do based on what I read. But they are amazing batteries!
Bobby people rave on a lot about not over flying the batteries etc etc, but my view is these are really a cheap expendable item. I rather enjoy slightly longer flight times than land to early just to squeeze an extra 10-20 flight out of them.
I look at it in this light. I pay around $45 for a 6000mAh 3S battery and I get about 35-45 good flights out of it before it starts to degrade. That's only about $1 per flight. Mate, in my book that's as cheap as chips for the pleasure. Even if I only got 20 flights out of it its only just over $2 a flight.
How many activities are at this cost for each round?
The prpos I really want to try are the TL2812 CF props, but they have been out of stock forever it seems...I found the wood props not long before reading your post, and I am curious about trying those as well.