Carbon propellers

I don't know about post #38.
But here is a repeatable test I made a few minutes ago. All props are DJI. Unbelievable, I know - CF are .2oz heavier per set. Not much difference, but definitely not lighter.

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wierd, someones scale is off :) ill have to pull out mine next time i fly my P2 or P3, typically CF are advertised as being lower weight , so i didn't doubt the measurement i linked to.
 
I use carbon blades when it's windy. The blades have less flex as they are Carbon, I feel my phantom is more responsive in its turns with carbon


Sent from my iPhone using PhantomPilots
 
Here is a flight of mine with CF props. I did not see any increase in speed, it did respond faster. Now one thing I did not think about, was the CF props using less power? I'll have to try the same flight with plastic OEM props and see if I get any different . To push a P3a to 22184 ft with a single battery I think is pretty good.
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I pulled the CF props out and my WIFE weight watcher scare. You know it's good.
The CF props came in a little heavier then the stock DJI props. I'm going to say because of the large center. One thing I did notice in my flight it was like I was flying on ice. Yes I have droven on ice. If you watch the video it was all over the place and I was trying to keep it straight. I did loss it coming back half was. lucky there was no ditches ;)
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wierd, someones scale is off :) ill have to pull out mine next time i fly my P2 or P3, typically CF are advertised as being lower weight , so i didn't doubt the measurement i linked to.
I also thought they would be lighter. But then I also thought you could see the fiber. The DJI CF blades show no evidence of fiber (must be micro fiber) I wish someone would examine a broken CF blade and see if there is any fiber in it. I'll be carbon but no fiber.
 
I pulled the CF props out and my WIFE weight watcher scare. You know it's good.
The CF props came in a little heavier then the stock DJI props. I'm going to say because of the large center. One thing I did notice in my flight it was like I was flying on ice. Yes I have droven on ice. If you watch the video it was all over the place and I was trying to keep it straight. I did loss it coming back half was. lucky there was no ditches ;)
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Now those blades look like actual carbon fiber (if it wasn't applied photographically) I've seen that too. They aren't DJI brand.
 
In my unscientific test yesterday, I compared the DJI CF props to OE and I agree the CF seem more responsive, but if anything are louder than the OE props. The noise may be subjective though. They are definitely different sounding, but the volume could be based on my selective frequency hearing loss (old age) :(
Or mine (old age). But I'll keep flying until the thumbs go.
 
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For what it's worth...

Years ago, I was working with RC helis adding heavy components to try to make them fly autonomously (this was 20+ years ago, when "drones" referred to a type of bee. My state of the art computer was a 386...Imagine 5 lbs of mechanical gyros, batteries, and radio serial ports, slung from a model helicopter) Anyway, as we approached the lifting capability of the helicopter, we saw that the wooden rotor blades began to flex. These are long and slender helicopter blades, mind you. As the blades flexed, they were much less efficient in developing lift. We solved the problem by having them wrapped in carbon fiber, which made them much stiffer, a bit heavier, and much more deadly when the shattered. Knife-like shards flying at terrific velocity!

So, while some of the dynamics are a bit different for the quadcopters' relatively short and stubby rotor blades, I imagine that some of the benefits some are seeing with rotors made of different (stiffer) material may be attributed, in part, to the same phenomena. It would be interesting for someone to clamp down their phantom (so it can't lift) and throttle it up with a camera focused at rotor level to see if the plastic, carbon fiber, or wooden rotor blades have any sort of appreciable flex under load. Sorry, I'm not willing to do this. My P3A is relatively new, and I'm still recovering from my last Phantom loss.

Getting cut by that carbon fiber rotor, even if it remains intact, sounds like a life-changing injury.
 
I haven't flown with them yet, but here's a pic of the tmotor carbon fiber props. Each prop is 8.4 / 8.5g.

PeEDfF1.jpg
 
The primary reason I am using 3 blade carbon fiber blades is in Florida during the winter it is usually a little windy and with both the extra blade and being made of carbon fiber I have much better performance especially when hovering, they will put greater stress on your air frame if you fly like a nut but that is not true in my case. Therefore I'm not overly concerned about anything cracking, I fly my Phantom 3 Pro. With a light touch. If your blades make more noise them they are not balanced well and you should have a prop. Balancer if you want stable video and less noise.


In many of the prop tests done CF props and 3 blade props all have shown to preform poorly compared to OEM props. Not only have they reduced battery life there seems to be a issue with stability. I have a few sets of HQ carbon nylon tri blades that I found to work well on my 550mm quad with Avroto 770kv motors on 4s but they are not the most efficient. Compared to 10,11 and 12x4.5 they produces less flight time.

DJI did a great job matching the props to the motors and there is really no need to look further for props that will improve performance.
 
Yup, more blades = less efficiency.

This is not a place for a more = better scenario.

Generally speaking....
Moving to three or more blades in aviation is done primarily to reduce disc diameter for things like ground or fuselage clearance or power availability.

However as with many such things there are other considerations in prop design and selection but in this case [a Phantom] where you are not changing the motors and ESCs nothing will outperform the OEM props which are part of a tuned propulsion system
 
I did buy a set of the DJI Carbon Nylon props to try out. I believe that I will see that same as others have. A bit more snappiness in response due to the more rigid construction.
 
I've been giving the stiff propellers argument some thought. I read a candidate-PhD's paper on quadcopter aerodynamics and although it was about a different (but related) flight characteristic, it did make me think of the stresses on the rotor blades during dynamic flight (transitions from hover to forward flight, changes of direction and altitude...basically any situation where the pilot commands a move from equilibrium). If I am flying at full speed in one direction, then slam the stick in the opposite direction, which components of the aircraft take the punishment? The rotor blades take a lot of it...the change in pitch of the rotor plane will cause them to bend (gyroscopic effects), precession effects, and a violent change in loading. I think the blades absorb a lot of those dynamics (through flexing). If very stiff rotor blades are used, I imagine that those same forces (which still exist) get transferred to the motors, the airframe, and specifically the bearings (where the motor casing (the rotor) sits on the stator (the screws that attach the motor mounts to the printed circuit board).

I guess I should get to my point--I think the more flexible OEM blades act as a sort of "shock absorber" and spare the motor mounts from a lot of the stress of dynamic maneuver. I wonder if using stiffer propeller blades won't result in the motor mounts (or airframe) failing sooner due to increased stresses. Has anyone broken an OEM blade simply from a violent maneuver (not from hitting something)?

Obviously, if you "fly it like you stole it" you are going to break something. My "somewhat informed / somewhat intuitive" opinion is this: If you use stiffer propellers hoping to get better performance (longer battery life, "snappier" response) then realize that you may be overstressing other parts of the airframe, *if* you perform high stress maneuvers. If you don't demand the aircraft to perform high stress maneuvers, then you will probably see some performance improvement, without adversely affecting the longevity of the airframe. I don't do high stress maneuvers, so I may consider stiffer propellers in the future.

I'm not the expert, and I don't plan on testing this, but it is my theory and opinion, based on what I've observed and what I know. Good luck!

(Now I need to see if I can find about $4K lying around so I can buy myself an Inspire 2 package !!)
 
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