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Old Sep 13, 2012, 11:13 AM
Blu-Core is my friend
Gundy's Avatar
La Crosse, WI
Joined Apr 2006
812 Posts
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Prop test DJI, Gemfan, Graupner, 10"

Ok this is the first of several test I am going to do.
I have 3 different sets of props (I may also add an APC prop)
For this test my DJI Naza with GPS. Stock motors and stock ESCs. I was using a 3s 5000 battery.
I am in my garage (because it is raining) This is a "hover" test. I used the same battery and just changed the props to see what the different amp draw was between the props.
I know I should have used a fresh battery for each test

The Props:
1. Stock DJI 10"
2. Gemfan Full Carbon Fiber Blades. There is some question about who makes them... but all the packaging said Gemfan and it came with stickers
3. Graupner, 10"

The next test is going to be hover to full power to 400'

Later,
Gundy

Prop test. DJI, Gemfan Full Carbon Fiber, Graupner, 10" hover test DJI Naza with GPS (5 min 49 sec)
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Old Sep 13, 2012, 01:03 PM
United States, MI, Goodrich
Joined Mar 2004
3,846 Posts
The one thing I have noted as well as others is the motors seem to run much cooler with the eProps. Strange because the eProps seem to pull the same amps as the CF GemFans.

We need GemFan props with the same profile as the eProps. I sent a request in to GemFan (or whoever) to see if they can make some that are like the eProps. I'm still surprised that there are not more companies that make props like the eProps.
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Old Sep 13, 2012, 10:03 PM
James not bond
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United States, MN, Minneapolis
Joined May 2012
2,074 Posts
i'll be more interested if you put them on balancer to show the out-of-box balance...
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Old Sep 13, 2012, 10:28 PM
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Joined Sep 2006
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What this test is really missing is motor RPM during the hover.

After watching the video and listening closely, it seems to me like the E props produce less thrust at the same RPM as the slow flyer props, but probably also less drag during hover due to the higher aspect ratio of the blade. You can hear the difference in RPM at hover pretty clearly.

This is why the E props draw less amps.. same could be accomplished by using a slow fly prop with less pitch.

At least that's what I took from it
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Old Sep 14, 2012, 10:50 AM
Blu-Core is my friend
Gundy's Avatar
La Crosse, WI
Joined Apr 2006
812 Posts
Quote:
Originally Posted by vic20owner View Post
What this test is really missing is motor RPM during the hover.
After watching the video and listening closely, it seems to me like the E props produce less thrust at the same RPM as the slow flyer props, but probably also less drag during hover due to the higher aspect ratio of the blade. You can hear the difference in RPM at hover pretty clearly.
This is why the E props draw less amps.. same could be accomplished by using a slow fly prop with less pitch.
At least that's what I took from it
I was thinking the same thing, about the RPMs. the rest is over my head.

I think the "climb" test is going to be a good one.
After that I am thinking about a hover vs. mah for 10min.
Later,
Gundy
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Old Sep 14, 2012, 11:30 AM
United States, MI, Goodrich
Joined Mar 2004
3,846 Posts
Great thread.

We do have some "special" Graupner style eProps requested in both the nylon/carbon and full CF versions from GemFan. Those will still be a few weeks out I'm sure.

As far as rpm reading you could just have your TX throttle curve open and see what % difference you get in a hover per say. Not sure how accurate that would be but maybe it would be a base line to go off of.
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Old Sep 14, 2012, 12:10 PM
Blu-Core is my friend
Gundy's Avatar
La Crosse, WI
Joined Apr 2006
812 Posts
I may need to hook up the Eagle Tree system I have, it has an rpm sensor.
I checked the balance on the carbon fiber props, they seem very good.
but they are so light it was tough to do, the flat spot did not help.

Someone needs to make a prop just for hovering craft... Oh wait...
Let me re-praise that. a fixed pitch super strong multi rotor prop.
Or maybe a fixed pitch hub so we can use helicopter blades that are already out there...

Later,
Gundy
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Old Sep 14, 2012, 12:16 PM
Blu-Core is my friend
Gundy's Avatar
La Crosse, WI
Joined Apr 2006
812 Posts
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Originally Posted by UAVProducts View Post
Great thread.

As far as rpm reading you could just have your TX throttle curve open and see what % difference you get in a hover per say. Not sure how accurate that would be but maybe it would be a base line to go off of.
I did check the throttle position on all three test. the Graupner took more stick to get going and a tiny bit more the 50% to hover.
the GemFan took the least amount to get going and hovered at 50%.

But DJI is supposed to alt hold at 50% so its hard to tell...

Later,
Gundy
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Old Sep 14, 2012, 12:25 PM
United States, MI, Goodrich
Joined Mar 2004
3,846 Posts
Quote:
Originally Posted by Gundy View Post
I did check the throttle position on all three test. the Graupner took more stick to get going and a tiny bit more the 50% to hover.
the GemFan took the least amount to get going and hovered at 50%.

But DJI is supposed to alt hold at 50% so its hard to tell...

Later,
Gundy
Might have to do it in manual mode.
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Old Sep 14, 2012, 12:58 PM
flitelab's Avatar
Canada, NS, Halifax
Joined Feb 2010
7,036 Posts
Quote:
Originally Posted by Gundy View Post
I did check the throttle position on all three test. the Graupner took more stick to get going and a tiny bit more the 50% to hover.
the GemFan took the least amount to get going and hovered at 50%.

But DJI is supposed to alt hold at 50% so its hard to tell...

Later,
Gundy
You pretty much have to test in manual mode to compare throttle position since it doesn't indicate much in ATT mode.
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Old Sep 14, 2012, 01:14 PM
Noob
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Canada, ON, Toronto
Joined Dec 2011
469 Posts
I like the sound of the gems the best.....
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Old Nov 04, 2013, 11:33 AM
quad lover
United States, MI, Ann Arbor
Joined May 2009
166 Posts
Quote:
Originally Posted by jy0933 View Post
i'll be more interested if you put them on balancer to show the out-of-box balance...

I just bought 4 GEMFAN carbon fiber props, and I mean the real carbon fiber. 8 bucks EACH prop (at my local hobby shop). I was skeptical because I purchased Gemfans in the past and they were so out of balance that it was not worth trying to fix.

Well it turns out that these beautiful carbon fiber props are just as out of balance as the regular ones I first tried months ago.

OH WELL. GEMFAN's will just always be out of balance when you open the package. If you want them, you gotta balance them. That must be Gemfan's policy.
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