Carbon Fiber Blades

[With The Birds]

I have 2 P4 2 p3s several race drones, a DJI hexacopter a yuneec hexcopter a yuneec breeze and 3 inspires. I am also a gulf vet who is about to crash from my xanax. Nice talking to ya mate. Thanks to you and all others for the input, imo I would not use cf props. They look cool, but the break easy.

True CF props may shatter on impact but would be very unlikely to break from any stress that might be applied to it then in flight. The problem is the so called CF props (not talking about DJI offerings here that are carbon composite rather than true CF) tend to be Chinese rubbish that are usually CF look alike or poorly made if true CF. you get 100's of flights from the standard pros without headaches. I'm with you.

 

[Erised]

Lets say you have CF and OEM props, the CF will bend less (till they snap), you are hovering or cruising, the CF props will requirer less RPM to give the same lift but will need more amps to rotate them. The energy requirered from the battery will be the same to lift a craft of the same weight off the ground, gravity is constant. The control moduel will max the amp draw and thats how fast you will go. More pitch = less RPM = X lift = Y amps...Less pitch = more RPM = same X lift = same Y amps. You are doing the same amount of work (mah) regardless of RPM variance to keep the craft airborn. The only area that could help would be in the design of the prop to attain the best pitch for the job and I think that DJI has this figured out very well. I think you may have get a little faster response and same top speed. For me the the risk of using CF are to great and OEM works fine. The pilot should be cool, the bird does not have to be.

 

[With The Birds]

Lets say you have CF and OEM props, the CF will bend less (till they snap), you are hovering or cruising, the CF props will requirer less RPM to give the same lift but will need more amps to rotate them. The energy rquirered from the battery will be the same to lift a craft of the same weight off the ground, gravity is constant. The control moduel will max the amp draw and thats how fast you will go. More pitch = less RPM = X lift = Y amps...Less pitch = more RPM = same X lift = same Y amps. You are doing the same amount of work (mah) regardless of RPM variance to keep the craft airborn. The only area that could help would be in the design of the prop to attain the best pitch for the job and I think that DJI has this figured out very well.

Energy required from the battery probably wont be the same for a given thrust from a different prop geometry- simply because the propulsion system will operate at different efficiencies for various RPM ranges. In your example higher current to drive a higher pitch prop at a slower RPM (for the same equivalent thrust) will cause increased temp in the motor windings increasing DCR and lowering efficiency.

 

[Erised]

Energy required from the battery probably wont be the same for a given thrust from a different prop geometry- simply because the propulsion system will operate at different efficiencies for various RPM ranges. In your example higher current to drive a higher pitch prop at a slower RPM (for the same equivalent thrust) will cause increased temp in the motor windings increasing DCR and lowering efficiency.

I agree they will exist effeciency variables and ambiant temperatures will be the greatest contributer. I live in northern Ontario and at this time when I land after a 20 minute flight my motors are cool to the touch. I would like to see stats on motor RPM in a hover, CF vs OEM and max hover time with each, the variable here would be to get a perfect battery match.