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Old Sep 05, 2013, 10:16 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,219 Posts
Mini-Review
Carbon Fiber to Plastic Prop Comparison Test

Carbon Fiber to Plastic Prop Comparison Test

These comparison flights were flown to compare a typical and widely used plastic prop to a typical better quality carbon fiber prop. The props compared were the GemFan 10x4.5 black plastic or polyester prop and iFlight iCF 10x 4.5 Carbon Fiber prop.

The tests were flown by user 2400RDR (Rick Lindstrom) on his "woody" quad. Rick's quad is your basic "industrial strength" scratchbuilt quad but don't let that cause you to think that it is shabby in any way.

And Rick's quad suffers least of all in quality of the components, performance, and piloting. Rick is using the OpenPilot CC3D flight controllers and I was really glad to get someone with his knowledge and skill to fly an eLogger around for me and gather some data.

The quad, seen in the first image, had four iPower MultiMate MT2212-850 KV motors for the tests and the all up weight was 930g with a 2200 mAH 3S pack. The same battery was used for both flights and the only change between flights was the props.

Test Flight Description

The test flight flown was a profile that has become standard for Rick and I to use in comparing motors and props. The second image is an example of a test flight that Rick flew on his tricopter with three DAT-750 motors that I rewound for him. That same profile is what was flown for these tests.

The first prop in the comparison flights was the GemFan 10x4.5 black plastic or polyester prop. This prop is called by a number of names and described various ways by various sellers. On the GemFan product pages, is called simply the 1045 or 1045R black prop.

The second prop was the iFlight iCF 10x 4.5 Carbon Fiber prop.

Images of the captured data from the eLogger, as seen in the Data Recorder app, are incuded below. The third through seventh images are for the GemFan prop and show the full test flight and then the four phases of the flight. The last five images show the same things for the test flight with the iCF Carbon Fiber prop.

The sequence of the test flight profile is:

1 - Takeoff and stable hover for one minute
2 - Transition to forward flight and do three full throttle punch outs
3 - Transition to fast foward flight for one minute
4 - Brief stable hover and landing.

The flight data from the eLogger and the statistics for the four phases of the flight are compared for the two props tested. In most cases the values are the averages for the stated period of time (in seconds), in some cases there will also be the peak readings that occurred during that phase of the test flight.

Read the results as:

Duration (seconds), Voltage, Current, Input Power, Batttery Capacity used

Takeoff and One Minute Hover

GemFan 10x4.5 averages - 52s 10.74V 10.87A 117W 157mAH
GemFan 10x4.5 peaks - 15.36A 157W

iCF 10 x 4.5 CF averages - 59s 10.00V 11.77A 107W 150mAH
iCF 10 x 4.5 CF peaks - 8.79A 116W

Three Full Throttle Punch Outs

GemFan 10x4.5 averages - 39s 10.13V 14.11A 139W 152mAH
GemFan 10x4.5 peaks - 33A 296W

iCF 10 x 4.5 CF averages - 35s 9.61V 13.22A 126W 133mAH
iCF 10 x 4.5 CF peaks - 29A 254W

Fast Forward Flight

GemFan 10x4.5 averages - 36s 9.41V 19.41A 180W 184mAH
GemFan 10x4.5 peaks - 28.73A 263W

iCF 10 x 4.5 CF averages - 36s 9.16V 15.15A 139W 197mAH
iCF 10 x 4.5 CF peaks - 27.41A 243W

Hover and Land

GemFan 10x4.5 averages - 11s 9.21V 11.92A 110W 35mAH
iCF 10 x 4.5 CF averages - 9s 9.23V 11.61A 107W 28mAH

Full Flight Averages & Cumulative mAH Totals

GemFan 10x4.5 averages - 136s 10.18V 13.61A 139W 529mAH
iCF 10 x 4.5 CF averages - 150s 9.81V 12.94A 121W 519mAH

Looking at the capacity used in the test flights and, assuming a typical 80% usable capacity of 1760 mAH from a 2200 mAH pack, if the above test flight was flown repeatedly and to use the full capacity, the pack duration for these two props would be estimated at about:

GemFan 10x4.5 prop = 7:49
iCF 10 x 4.5 CF prop = 8:16

So what are the conclusions from the test?

Rick's first impression was that of how much quieter the carbon fiber props are than the plastic props. And also that the CF props use the power a little better, require a little less throttle, and have a little more "snap" as far as acceleration and response.

My conclusions, from looking at the statistics, parallel Ricks. The CF props attain a higher RPM for the same input power and can deliver the same amount of thrust with less power. And those combine to contribute to better battery duration.

And, while Rick does not do any crash testing comparisons, the CF props were obviously stronger and will undoubtedly resist damage in minor brushes with the ground or other objects better than the polyester props would.

So all things considered the CF props are certainly worth a try and there will be some real benefits that offset the higher costs.

Jack
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Old Sep 05, 2013, 11:11 AM
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Blackrat's Avatar
South Africa, WC, Knysna
Joined May 2006
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awesome test

thanks for the time
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Old Sep 07, 2013, 05:25 PM
Smokes
Australia, VIC, Kilsyth
Joined Jul 2007
220 Posts
Impressive tests and informative too. That's what I like about science rather than opinion, you get actual figures. Many thanks Jackerbes.

One question regarding the crash testing (or lack of): while the CF props are obviously far more durable than 'plastic' and hold their shape better in flight (helping efficiency no doubt) common sense suggests there would be a higher chance of damage during a crash to other components like motors if CF props were used due to the lack of 'give' with a CF prop compared to plastic. I guess if this was true it would be a matter of balancing the cost of replacement parts to restore an aircraft to precrash condition including the cost of props. In other words, if efficiency wasn't the prime consideration should the cost of replacing cheaper props be a factor to consider when compared to the possible additional replacement cost of motors when CF props are used?

I'm rambling I know but it's something that popped into my head.
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Old Sep 07, 2013, 09:23 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,219 Posts
"

Quote:
Originally Posted by smokes View Post
Impressive tests and informative too. That's what I like about science rather than opinion, you get actual figures. Many thanks Jackerbes.
Thanks for the kind words, and just Jack works for me...

Quote:
One question regarding the crash testing (or lack of): while the CF props are obviously far more durable than 'plastic' and hold their shape better in flight (helping efficiency no doubt) common sense suggests there would be a higher chance of damage during a crash to other components like motors if CF props were used due to the lack of 'give' with a CF prop compared to plastic.
You right about that. I got into electric RC building 20+ oz. versions of Blu Baby 33's that other were putting in the air at 10 oz. It is my habit to try to crash proof things I guess...

Quote:
I guess if this was true it would be a matter of balancing the cost of replacement parts to restore an aircraft to precrash condition including the cost of props. In other words, if efficiency wasn't the prime consideration should the cost of replacing cheaper props be a factor to consider when compared to the possible additional replacement cost of motors when CF props are used?

I'm rambling I know but it's something that popped into my head.
Ironically, I have been pursuing this lately and I'll tell you about it. A while back I built my first multi, a RC Explorer V2.5 tricopter with G10 frame plates and wooden arms. Getting the motors on, KK20 board and ESCs flashed, and getting it in the air took me some months as I was not in a hurry.

I put all clockwise Great Planes 10 x 4.5 SF props on it because I had them on hand and didn't care if it flew a little out of level. It only has about five minutes in the air as of now. In the first flights I broke two of the GP props on ground dings or from it falling out of the air when I lost the bubble on things and just closed the throttle. I also broke two of the wooden arms so far.

The broken arms have been replaced. I upgraded the arm material from the generic Chinese 1/2" square white wood from Home Depot to 1/2" square maple arms from America. The initial penalty was that the arms went from 25 grams to 52 grams. I'm waiting to see if the stronger arms will break something else but it has not happened yet.

I had ordered four sets of CW/CCW 11 x 4.7 CF props from iFlight RC's online store and those wound up costing me a little less than $4 each with shipping.

So the other day I also upgraded to the CF props as I was replacing the second wood arm. I have not had a chance to go to my flying place but did some of what I call "short lift and land" test in the yard to see if the tri was ready to go to the flying field. In the course of one of those lift and land tests I had a wreck...

I got one side low enough that I dropped the tri onto one arm at about a 45 degree angle. The ground was soft and damp from recent rains, one of the brand new CF props buried itself almost up to the prop adapter in the grass and earth. I was already off the throttle when it hit. I gather it up, scurried back to the basement (No! I was not in tears, at 71 years I have outgrown that!).

And the postmortem inspection showed that I only had to wipe the muddy earth from an otherwise undamaged CF prop. And I also found that the leverage of the buried prop on the motor and "X" mount had bent the "X" mount so that the motor was canted on the arm 8-10 degrees or so. I got the mount off (the maple arm was undamaged), pressed the soft aluminum "X" back to perfectly flat between the jaws of a vise, and got it all back together.

The tri has since had a low RPM run up on the table to check everything out and it is ready for my next attempt to at learning to fly a multi. In my brief excursion into the lift and lands with the CF props, I could already tell that they had more power and they also seemed more controllable in the brief time I had them in flight.

My tricopter has 450mm arms and weighs 1250 grams with a 4500 mAH 3S pack strapped under it and an eLogger that is going to go along for the ride.

It has three iPower MT4008-620KV motors on it (those are now called the iPower iBM4008Q 620KV motor). Those are 119 gram motors and should be able to put an easy 250W or so into those props if they want it.

I'm looking for a stable, slow flying, non-acrobatic, flyer and thing this might work for me once I master the basics.

So your ramblings are right about the way one good thing can do some not so good things. But it all counts on the learning curve for me...

Jack
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Old Sep 08, 2013, 05:54 AM
Smokes
Australia, VIC, Kilsyth
Joined Jul 2007
220 Posts
Thanks for another good yarn Jack. Good to hear that old blokes like us (I'm 61) are having fun with multis.

Andrew
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Old Sep 08, 2013, 06:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,219 Posts
I went through some of the usual "I wonder if this is worth all the trouble" trials in the course of getting to this point. But I'm already starting to feel better about it. I guess that is normal.

Multis are a strange aircraft. I got into RC as an electric only guy and only about five years ago. So my first plane (a RTF SklyFly) had a brushed motor and used a NiMH pack. And that was my last brushed motor and NiMH pack too.

Can you imagine that the multi thing ever would have happened if it had not been for LiPO packs and brushless outrunner motors? It it had, guys would probably be whooping and high fiving each other over managing to get two minute flights out of a quad.

Jack
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Old Sep 13, 2013, 03:02 PM
Watching EKRAN
Joined Jul 2013
420 Posts
Quote:
Originally Posted by jackerbes View Post
Can you imagine that the multi thing ever would have happened if it had not been for LiPO packs and brushless outrunner motors? It it had, guys would probably be whooping and high fiving each other over managing to get two minute flights out of a quad.
It might, or might not. All the electronics is probably more important, I suppose a quad could launch in the airs with high grade brushed motors, but it's all the chips that make humans able to fly one.

I've been trying to get my Dad into flying quads, he's still a few years younger than you Jack Not much success yet, I think it's all a motivation issue, he tried the X4 once and has been learning the Syma X1 (a great craft too, I think), but just 1 battery at a time. I think he'll soon learn to hover if he keeps doing it
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Old Mar 07, 2014, 01:07 PM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
5,390 Posts
Jack.

What is a limit to the propeller RPM CF iflight.
With 11x4.7 I am getting 8600 rpm at 327 watts.
Be sure, is not vibrate at all.

Manuel V.
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Old Mar 07, 2014, 04:12 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,219 Posts
They do not publish a maximum RPM. I have hit 12,000 momentarily and run them at 10,000 for minutes at a time. I have not yet had a blade separation or any vibrations or other indications of danger. And there is very little or no forward flexing at the tip under load when I looked at from the side.

I think we are just going to have to decide for ourselves what the RPM limit is.

When I balance those I put small strips of clear package sealing tape on the back of the blades. But they have needed very little balancing. One or two of the 15 or so I have for testing also required some balancing at the hub too.

Dr Kiwi and I tested the same props under two different names, you can see our testing data here:

iFlight-RC iCF 11x4.7 - http://www.flybrushless.com/prop/view/348

iFlight CF 11x4.7 - http://www.flybrushless.com/prop/view/348

If you compare the CF props to the APC SF11 x 4.7 it is kind of interesting:

APC SF 11x4.7 - www.flybrushless.com/prop/view/44

It is like you can get the same thrust with less power when you use the CF. And then the CF has a higher RPM and also seems to keep on pulliing for several thousand RPM more.

Jack
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